Article

Nocturnal and diurnal foraging behaviour of brown bears ( Ursus arctos ) on a salmon stream in coastal British Columbia

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Abstract

Brown bears (Ursus arctos) have been reported to be primarily diurnal throughout their range in North America. Recent studies of black bears during salmon migration indicate high levels of nocturnal foraging with high capture efficiencies during darkness. We investigated the extent of nocturnal foraging by brown bears during a salmon spawning migration at Knight Inlet in coastal British Columbia, using night-vision goggles. Adult brown bears were observed foraging equally during daylight and darkness, while adult females with cubs, as well as subadults, were most prevalent during daylight and twilight but uncommon during darkness. We observed a marginal trend of increased capture efficiency with reduced light levels (day, 20%; night, 36%) that was probably due to the reduced evasive behaviour of the salmon. Capture rates averaged 3.9 fish/h and differed among photic regimes (daylight, 2.1 fish/h; twilight, 4.3 fish/h; darkness, 8.3 fish/h). These results indicate that brown bears are highly successful during nocturnal foraging and exploit this period during spawning migration to maximize their consumption rates of an ephemeral resource.

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... Previous studies of Asian black bears (Ursus thibetanus) using GPS radio collars have shown that they reduce summer activity to avoid energy depletion and become more active during the hyperphagia season to intercept more food [11,25]. In addition, adult brown bears in some populations have been reported to increase their nocturnal activity in autumn [20,39]. The current study also demonstrated that adult bears shifted their diel pattern from crepuscular and/or diurnal to cathemeral in September and October, 1146-1156, 2022 suggesting that they extended their activity time to consume a high-calorie diet, including salmon and acorns. ...
... A similar difference was found between adult males and adult females. It has been reported that females with offspring become diurnal to decrease the chance of male encounters and the risk of infanticide [3,20,43]. In some populations, infanticide by adult males was the major cause of death for cubs-of-the-year [2,59]. ...
... Another possible factor is social dominance. For example, large adult males dominate the most productive area and time (night-time and twilight) for catching salmons [20], which may make females and sub-adults more diurnal. Also, there may be males' matter, e.g., larger males may receive more heat stress than females and sub-adults do in hot weather, which makes adult males more nocturnal/crepuscular. ...
Article
Mammals exhibit several types of diel activity pattern, including nocturnal, diurnal, crepuscular, and cathemeral. These patterns vary inter- and intra-specifically and are affected by environmental factors, individual status, and interactions with other individuals or species. Determining the factors that shape diel activity patterns is challenging but essential for understanding the behavioral ecology of animal species, and for wildlife conservation and management. Using camera-trap surveys, we investigated the species distributions and activity patterns of terrestrial mammals on the Shiretoko Peninsula, Hokkaido, Japan, with particular focus on brown bears and sika deer. From June to October 2019, a total of 7,530 observations were recorded by 65 camera-traps for eight species, including two alien species. The diel activity pattern of brown bears was diurnal/crepuscular, similar to that of bears in North America, but different from European populations. Bear observations were more frequent during the autumnal hyperphagia period, and adult females and sub-adults were more diurnal than adult males. In addition, bears inside the protected area were more diurnal than those outside it. These findings suggest that appetite motivation, competitive interactions between conspecifics, and human activities potentially affect bear activity patterns. Similar to other sika deer populations and other deer species, the diel activity patterns of sika deer were crepuscular. Deer showed less variation in activity patterns among months and sex-age classes, while adult males were observed more frequently during the autumn copulation period, suggesting that reproductive motivation affects their activity patterns.
... Bear behaviour, including foraging strategies, is very adaptable giving bears the ability to compensate for factors that alter their natural behaviours (Gilbert 1989). Spatio-temporal compensation for human activity at bear viewing areas has been documented on numerous occasions (e.g., Klinka and Reimchen 2002, Crupi 2003. Similarly, bears along the Fishing Branch River may have adapted spatial or temporal compensatory behaviours for viewer presence, such as increasing their nocturnal foraging or maximizing their foraging in lower human activity areas. ...
... I found that fishing bout length was the most important variable for predicting consumption and was positively related with fish consumption. I expected this positive relationship because bears should consume more salmon the longer they fish until limited by gut capacity (Klinka and Reimchen 2002). ...
... Boyd and Silk (1983) (Berns et al. 1980, Ballard et al. 1982, Barnes 1990). As such, male bears likely prefer fishing on larger streams where salmon are often more abundant (Gende and Quinn 2004) resulting in male bears being dominant at larger streams, such as Glendale River (Klinka andReimchen 2002, Nevin and and McNeil River (Egbert and Stokes 1976). Dominance by large females at two smaller spawning streams in Alaska (Himmel and Bear Creeks) may be an artifact of this varying abundance of salmon streams in home ranges (Gende and Quinn 2004). ...
Thesis
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Wildlife-based ecotourism is rapidly increasing in popularity, especially when featuring large mammals in their natural environment. Researchers have questioned the sustainability of wildlife-based ecotourism because it may compromise the survival and reproduction of focal animals. I investigated the potential spatio-temporal effects of bear viewers on grizzly bears at a proposed bear viewing site along the Fishing Branch River, Yukon. Spatial river use of grizzly bears was largely explained by habituation status. Bears consumed 24% less salmon when viewers were present, posing serious energetic consequences if spatio-temporal compensation does not occur. Dominance status had no measurable effect on bears' fishing behaviour presumably because abundant salmon and few conspecifics minimized resource-driven competition. However, dominance status could influence feeding behaviour in years with reduced salmon abundance, which would compound viewer-induced reductions in fish consumption. I recommend further investigation into spatio-temporal compensatory behaviours of grizzly bears along the Fishing Branch River.
... Oncorhynchus clarkii cutthroat trout Species Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus gorbuscha pink salmon Species Sizemore 1980, Barnes Jr. 1990, Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus keta chum salmon Species Sizemore 1980, Barnes Jr. 1990, Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus kisutch coho salmon, silver salmon Species Barnes Jr. 1990, Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus mykiss rainbow trout, steelhead Genus Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus nerka sockeye salmon, kokanee Species Sizemore 1980, Barnes Jr. 1990, Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013, Deacy et al. 2017 Fish ...
... Oncorhynchus clarkii cutthroat trout Species Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus gorbuscha pink salmon Species Sizemore 1980, Barnes Jr. 1990, Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus keta chum salmon Species Sizemore 1980, Barnes Jr. 1990, Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus kisutch coho salmon, silver salmon Species Barnes Jr. 1990, Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus mykiss rainbow trout, steelhead Genus Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus nerka sockeye salmon, kokanee Species Sizemore 1980, Barnes Jr. 1990, Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013, Deacy et al. 2017 Fish ...
... Oncorhynchus clarkii cutthroat trout Species Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus gorbuscha pink salmon Species Sizemore 1980, Barnes Jr. 1990, Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus keta chum salmon Species Sizemore 1980, Barnes Jr. 1990, Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus kisutch coho salmon, silver salmon Species Barnes Jr. 1990, Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus mykiss rainbow trout, steelhead Genus Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013 Fish Oncorhynchus nerka sockeye salmon, kokanee Species Sizemore 1980, Barnes Jr. 1990, Klinka and Reimchen 2002, Barker 2011, Fortin et al. 2013, Deacy et al. 2017 Fish ...
Technical Report
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The North Cascades Ecosystem of north-central Washington State and southern British Columbia, Canada, is one of six designated recovery zones for grizzly bears (Ursus arctos) in the conterminous United States. The National Park Service and US Fish and Wildlife Service evaluated a range of alternatives for restoring grizzly bears in the Cascades, and carrying capacity models estimated the ecosystem could support approximately 250–300 bears under current habitat conditions. As climate change shapes the North Cascade Ecosystem, there is considerable uncertainty as to how grizzly bear habitat may change through time. Projected increases in growing season length, winter and spring water surplus, summer water deficit, wildfire, and decreases in snow pack will likely to lead to substantial vegetation changes by the end of the century. These changes are in turn likely to affect grizzly bear foraging and denning behaviors, and thus could influence their population dynamics through time. The North Cascades Ecosystem supports many of the primary food sources used by grizzly bears in other populations, including graminoids, starchy tubers like Hedysarum spp., montane forbs like glacier lilies, forest plants like horsetails and cow parsnip, clovers, and a wide variety of berry-producing plants (Vaccinium spp. and others), as well as ants, ungulates, and carrion. Because grizzly bears are habitat generalists, they are projected to be relatively insensitive to climate change effects. More grizzly bear food resources in the North Cascades are expected to increase in abundance over time than those projected to become more scarce. For example, some important bear food sources, like Vaccinium spp., are projected to significantly increase in abundance as meadows become shrubbier and fire opens forests over the coming decades. Many grizzly bear food sources are projected to migrate up in elevation, potentially creating higher quality habitat farther from low elevation roads and human settlements where human-bear conflict is more likely. Disease and pest outbreaks such as blister rust disease in whitebark pine, beetle infestations of conifer forests, and salmon poisoning disease introduce a suite of uncertainties for the future of specific potential grizzly bear foods. Changes in winter snowpack may delay denning, exposing grizzly bears to negative human interactions for a longer period of time each year, underscoring the importance of human sanitation practices and education. The complex relationship between changes in climate, natural processes, and natural and anthropogenic features will expose grizzly bears to a range of changing resource conditions, but the species low sensitivity to changing climate and high adaptive capacity portends positive long term outcomes if a successful founding population can be re-established. This report aims to synthesize the scientific literature and develop the conceptual basis for understanding potential climate impacts on grizzly bear habitat quality in the North Cascades Ecosystem. It is expected that the outcome of this effort will be used to inform modeling efforts for estimating grizzly bear carrying capacity under future climate change scenarios.
... An important question is whether the consequences of hunter-caused disturbances are great enough to influence population growth. To maximize food intake, foraging bears select locations providing the biggest energetic gain (Hertel et al. 2016a) or forage at times when prey detection is easiest (MacHutchon et al. 1998) and prey are most vulnerable (Klinka andReimchen 2002, 2009). For instance, brown bears are very efficient in preying on Pacific salmon (Oncorhynchus spp.) and reindeer calves (Rangifer tarandus) at night (Klinka andReimchen 2002, Ordiz et al. 2017), whereas bears forage in the best berry habitat patches during the crepuscular and light hours (McLellan andMcLellan 2015, Hertel et al. 2016b). ...
... An important question is whether the consequences of hunter-caused disturbances are great enough to influence population growth. To maximize food intake, foraging bears select locations providing the biggest energetic gain (Hertel et al. 2016a) or forage at times when prey detection is easiest (MacHutchon et al. 1998) and prey are most vulnerable (Klinka andReimchen 2002, 2009). For instance, brown bears are very efficient in preying on Pacific salmon (Oncorhynchus spp.) and reindeer calves (Rangifer tarandus) at night (Klinka andReimchen 2002, Ordiz et al. 2017), whereas bears forage in the best berry habitat patches during the crepuscular and light hours (McLellan andMcLellan 2015, Hertel et al. 2016b). ...
... To maximize food intake, foraging bears select locations providing the biggest energetic gain (Hertel et al. 2016a) or forage at times when prey detection is easiest (MacHutchon et al. 1998) and prey are most vulnerable (Klinka andReimchen 2002, 2009). For instance, brown bears are very efficient in preying on Pacific salmon (Oncorhynchus spp.) and reindeer calves (Rangifer tarandus) at night (Klinka andReimchen 2002, Ordiz et al. 2017), whereas bears forage in the best berry habitat patches during the crepuscular and light hours (McLellan andMcLellan 2015, Hertel et al. 2016b). Bears have a limited period to acquire resources prior to hibernation, so any alteration to their foraging behavior may have negative effects on their body condition and fitness (Hertel et al. 2016b). ...
Article
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Harvest by means of hunting is a commonly used tool in large carnivore management. To evaluate the effects of harvest on populations, managers usually focus on numerical or immediate direct demographic effects of harvest mortality on a population's size and growth. However, we suggest that managers should also give consideration to indirect and potential evolutionary effects of hunting (e.g., the consequences of a change in the age, sex, and social structure), and their effects on population growth rate. We define “indirect effects” as hunting-induced changes in a population, including human-induced selection, that result in an additive change to the population growth rate “lambda” beyond that due to the initial offtake from direct mortality. We considered 4 major sources of possible indirect effects from hunting of bears: (1) changes to a population's age and sex structure, (2) changes to a population's social structure, (3) changes in individual behavior, and (4) human-induced selection. We identified empirically supported, as well as expected, indirect effects of hunting based primarily on >30 years of research on the Scandinavian brown bear (Ursus arctos) population. We stress that some indirect effects have been documented (e.g., habitat use and daily activity patterns of bears change when hunting seasons start, and changes in male social structure induce sexually selected infanticide and reduce population growth). Other effects may be more difficult to document and quantify in wild bear populations (e.g., how a younger age structure in males may lead to decreased offspring survival). We suggest that managers of bear and other large carnivore populations adopt a precautionary approach and assume that indirect effects do exist, have a potential impact on population structure, and, ultimately, may have an effect on population growth that differs from that predicted by harvest models based on direct effects alone.
... Bears spent less time fishing when anglers and bear-viewers were present [83] and had decreased fishing success [83,92] compared to when anglers and bear-viewers were absent. In areas where males were displaced by bear-viewing [87,93] or angling and bear-viewing [92], an increase in females with cubs was sometimes seen. In areas where adult male brown bears temporally avoid bear-viewers and anglers, females with cubs have increased access to salmon [59,61,63,75,84,86,87,91,92,93,94]. ...
... In areas where males were displaced by bear-viewing [87,93] or angling and bear-viewing [92], an increase in females with cubs was sometimes seen. In areas where adult male brown bears temporally avoid bear-viewers and anglers, females with cubs have increased access to salmon [59,61,63,75,84,86,87,91,92,93,94]. ...
... bear-viewing from designated platforms, or temporally controlled, by limiting bear-viewing hours, to allow bears to access the resource while avoiding humans. Temporally displaced bears at salmon streams may not experience a decreased fishing rate because darkness may reduce the evasive responsiveness of salmon and salmon are more active at night [93,112]. The BNM gives managers the ability to compare changes in nutritional intake, energetic costs, reproduction, cub survival, and adult survival as they make changes in the model to the levels of recreational activities and whether the activities occur in a regulated or unregulated manner. ...
Article
Full-text available
Increased popularity of recreational activities in natural areas has led to the need to better understand their impacts on wildlife. The majority of research conducted to date has focused on behavioral effects from individual recreations, thus there is a limited understanding of the potential for population-level or cumulative effects. Brown bears (Ursus arctos) are the focus of a growing wildlife viewing industry and are found in habitats frequented by recreationists. Managers face difficult decisions in balancing recreational opportunities with habitat protection for wildlife. Here, we integrate results from empirical studies with expert knowledge to better understand the potential population-level effects of recreational activities on brown bears. We conducted a literature review and Delphi survey of brown bear experts to better understand the frequencies and types of recreations occurring in bear habitats and their potential effects, and to identify management solutions and research needs. We then developed a Bayesian network model that allows managers to estimate the potential effects of recreational management decisions in bear habitats. A higher proportion of individual brown bears in coastal habitats were exposed to recreation, including photography and bear-viewing than bears in interior habitats where camping and hiking were more common. Our results suggest that the primary mechanism by which recreation may impact brown bears is through temporal and spatial displacement with associated increases in energetic costs and declines in nutritional intake. Killings in defense of life and property were found to be minimally associated with recreation in Alaska, but are important considerations in population management. Regulating recreation to occur predictably in space and time and limiting recreation in habitats with concentrated food resources reduces impacts on food intake and may thereby, reduce impacts on reproduction and survival. Our results suggest that decisions managers make about regulating recreational activities in time and space have important consequences for bear populations. The Bayesian network model developed here provides a new tool for managers to balance demands of multiple recreational activities while supporting healthy bear populations.
... At first sight, the crepuscular pattern exhibited by the female bears did not seem to be optimal according to optimal foraging theory. Although the sensory modes for foraging are not well known in brown bears, we excepted that females in our study area should exhibit the same diurnal activity as observed in North American brown bear populations (Gende et al. 2001, Klinka & Reimchen 2002, because their diet component (forbs, berries, ants) should be more detectable during daylight (Klinka & Reimchen 2002). Indeed, in North America, several brown bear populations have been reported to be active during the day (Klinka & Reimchen 2002). ...
... At first sight, the crepuscular pattern exhibited by the female bears did not seem to be optimal according to optimal foraging theory. Although the sensory modes for foraging are not well known in brown bears, we excepted that females in our study area should exhibit the same diurnal activity as observed in North American brown bear populations (Gende et al. 2001, Klinka & Reimchen 2002, because their diet component (forbs, berries, ants) should be more detectable during daylight (Klinka & Reimchen 2002). Indeed, in North America, several brown bear populations have been reported to be active during the day (Klinka & Reimchen 2002). ...
... Although the sensory modes for foraging are not well known in brown bears, we excepted that females in our study area should exhibit the same diurnal activity as observed in North American brown bear populations (Gende et al. 2001, Klinka & Reimchen 2002, because their diet component (forbs, berries, ants) should be more detectable during daylight (Klinka & Reimchen 2002). Indeed, in North America, several brown bear populations have been reported to be active during the day (Klinka & Reimchen 2002). However, bears tend to shift to nocturnal activity in areas with high human density (Klinka & Reimchen 2002) to avoid disturbance. ...
... We placed a life-sized bear model in a stream and observed that migrating salmon avoided the black model more than the white model, passing at a greater distance and showing abrupt evasive responses in proximity to the model. Positioning a stationary model in the middle of the stream is ecologically realistic as this "standing" technique is the most common stream foraging method used by both black bears and grizzly bears (Reimchen, 1998;Klinka & Reimchen, 2002, 2009a. We used modular components on an aluminum frame that allowed us to independently alter below-surface (legs) and abovesurface (body) effects for each coat colour. ...
... Such interactions have continuity back to the late Pliocene when Ursus emerged (Talbot & Shields, 1996;Luna-Arangur et al., 2020) and could have favoured an adaptive behavioural predisposition in salmon for increased avoidance of shapes associated with this predator. Because the high salmon capture rate that bears exhibit, often at low light levels (Reimchen, 1998(Reimchen, , 2000Klinka & Reimchen, 2002, 2009a and predominantly in turbulent streams, implies high fitness benefit to salmon that respond rapidly. This may be equivalent to previous evidence that salmon have an innate behavioural avoidance to weak concentrations of chemical extracts from tissues extracted from bears (Brett & MacKinnon, 1954). ...
Article
The white colour morph of the black bear (Ursus americanus kermodei) occurring on islands on the coast of British Columbia, western Canada, captures more salmon (Oncorhynchus spp.) than does the black morph and is hypothesized to have reduced contrast against the sky from the visual perspective of the salmon. We tested this hypothesis in a natural salmon stream by recording the number and proximity of chum salmon (Oncorhynchus keta) approaches (N = 1617 fish, 91 trials) towards life-size bear models differing in body and leg coloration under a mixed forest-sky canopy. Although salmon approached the white models at a much higher rate than black models, consistent with camouflage, we found greater abrupt evasions to the black models, largely independent of their contrast against the above-surface or below-surface backgrounds. Upward-facing sub-surface video-imaging through the rippled water-air interface indicated major visual fragmentation of the model’s integrity. We suggest that increased evasiveness to black models reflects an evolutionary response due to 3+ million years of trophic interaction between salmon and bears, and that the major differences between calm vs. rippled conditions through the optical cone (Snell’s window) at the water-air interface remains a largely unexplored theme in assessing foraging preferences and adaptive coloration within and among species using the water-air interface.
... Except for winter, when brown bears are typically hibernating in dens, bears are active for approximately 50% of the day (Ordiz et al. 2011;Seryodkin et al. 2013). Brown bears display mostly crepuscular and nocturnal activity in humandominated landscapes (Kaczensky et al. 2006;Seryodkin et al. 2013), are more active at daytime in remote areas or when they rely on some specific foods (Klinka & Reimchen 2002), and tend to be more diurnal when days are becoming shorter (Ordiz et al. 2013). Brown bears seem to be more nocturnal in Europe than in North America, which may reflect the longer history of persecution in Europe (Kaczensky et al. 2006;Ordiz et al. 2011). ...
... Subadults can display an intermediate behavior, being more active during daytime than adult bears (Kaczensky et al. 2006;Hertel et al. 2019b). This may allow subadult bears to access food resources at times when adults are less active, likely to reduce the risks of intraspecific aggression (Klinka & Reimchen 2002). In human-dominated landscapes, greater subadult activity during the daytime may also reflect a lack of experience in encounters with humans or human activities, which might be a major reason why adult bears are mostly active at night (Kaczensky et al. 2006). ...
Chapter
Bears have fascinated people since ancient times. The relationship between bears and humans dates back thousands of years, during which time we have also competed with bears for shelter and food. In modern times, bears have come under pressure through encroachment on their habitats, climate change, and illegal trade in their body parts, including the Asian bear bile market. The IUCN lists six bears as vulnerable or endangered, and even the least concern species, such as the brown bear, are at risk of extirpation in certain countries. The poaching and international trade of these most threatened populations are prohibited, but still ongoing. Covering all bears species worldwide, this beautifully illustrated volume brings together the contributions of 200 international bear experts on the ecology, conservation status, and management of the Ursidae family. It reveals the fascinating long history of interactions between humans and bears and the threats affecting these charismatic species.
... With respect to their daily activity, brown bears have primarily been found to be diurnal [6,18], with peaks of activity in the early morning and evening. Some subpopulations have also been reported to be crepuscular or nocturnal [11,19,20]. A large proportion of their daily waking activity is thought to be foraging and eating, with bouts of rest and travel [8,9,12,13]. ...
... A large proportion of their daily waking activity is thought to be foraging and eating, with bouts of rest and travel [8,9,12,13]. Brown bears have shown flexibility in their daily activity based on weather [6], light levels [19], age [2,13,14], and anthropogenic influences [7,18,21,22]. Seasonal and local changes in diet are thought to influence both circannual and circadian rhythms [11,23]. ...
Article
Full-text available
Captive grizzly bears, like their wild counterparts, engage in considerable variability in their seasonal and daily activity. We documented the year-long activity of two grizzly bears located at the Woodland Park Zoo in Seattle, Washington. We found that behaviors emerged in relation to month-to-month, seasonal, and time of day (hour-to-hour) observations, and events that occurred on exhibit, such as daily feedings. Seventeen behaviors split into seven classes of behavior were observed during their on-exhibit time over a 13-month period. Inactivity was the most frequent class of responses recorded, with most inactive behaviors occurring during the winter months. Both stereotypic and non-stereotypic activity emerged during the spring and summer months, with stereotypic activity occurring most frequently in the morning and transitioning to non-stereotypic activity in the latter part of the day. Results are discussed with respect to how captive grizzly bear behaviors relate to their natural seasonal and daily activity, as well as how events, such as feeding times and enrichment deliveries, can be used to optimize overall captive bear welfare.
... Many studies found that wild brown bears exhibit a wide variety of activity patterns that influence their survival or Communicated by: Krzysztof Schmidt reproductive output (Fortin et al. 2016;Hertel et al. 2016;Frank et al. 2017). While in North America, brown bears are largely diurnal (Klinka and Reimchen 2002;Munro et al. 2007); European populations predominantly exhibit nocturnal and crepuscular patterns (Olson et al. 1998;Kaczensky et al. 2006;Ordiz et al. 2014; but see Zarzo-Arias et al. 2018). The type and the intensity of disturbances vary seasonally. ...
... However, our results showed that females with offspring and subadults were mainly detected during the day. Several reports on brown bears in Europe and North America indicated that females with offspring modify their activity to more diurnal (Gunther 1990;Klinka and Reimchen 2002). Diurnal behavior might minimize male encounters' probabilities and infanticide risk (McLellan 2005;Bellemain et al. 2006a;Ordiz et al. 2011;Steyaert et al. 2013). ...
Article
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Mammals usually adjust behavioral patterns when exposed to disturbances. Elusiveness and low-risk time selection may reduce their stress in periods of highest risk. In Europe, brown bears (Ursus arctos) coexist with humans in densely populated and modified landscapes and, consequently, are exposed to human-caused disturbances during the daytime hours. Furthermore, intraspecific interactions might also influence their behavioral responses, especially during the mating season. Activity patterns of several large carnivores have been thoroughly studied; however, research is scarce for relocated populations. Here, we report the activity patterns in the reintroduced brown bear population in the Pyrenees. We expected the bears to reduce their activity depending on the type and level of disturbances. We analyzed individual behavior of both sexes (males, solitary females, and females with offspring) and age groups (adults and subadults) using camera-trap surveys under different types of intraspecific and anthropogenic disturbances. In general, bears were more active during the night (2200–0600 h) and avoided peaks of human activity (1000–1800 h). Furthermore, with the increasing nocturnal disturbance of adult males during the mating season, females with offspring and subadults were more active during daylight. This suggests that vulnerable individuals showed high tolerance for human presence. These results contribute to improve our knowledge of how a threatened and relocated bear population behaves in a human-modified landscape of southern Europe. Further research on this population will be crucial to establish optimal management interventions during translocations, and the prevention of human-bear encounters and conflicts.
... Brown bear (Ursus arctos) movements vary throughout time (Ordiz et al., 2014) and are influenced by numerous factors, including reproductive maturity, sex (Dahle & Swenson, 2003a) and daylight (Klinka & Reimchen, 2002;Klinka & Reimchen, 2009). Bears are also sensitive to changes in environmental conditions (Moln ar et al., 2010;Zarzo-Arias et al., 2018) and human activity (Martin et al., 2010;Ordiz et al., 2017), often seeking refuge in areas with rough terrain, far from human settlements [(Nellemann et al., 2007), but see also Elfstr€ om et al., (2014)] and roads [(Reynolds-Hogland & Mitchell, 2007;Skuban et al., 2017;Find'o et al., 2018), but see also Roever, Boyce & Stenhouse, (2010)] and close to forests and forest edges (May et al., 2008;Stewart et al., 2013). ...
... Nevertheless, this predominantly nocturnal movement pattern is interrupted when specific biological functions, such as mating (Fernandez-Gil, Naves & Delibes, 2006) or denning preparation, need to be fulfilled. In contrast, the more diurnal movement patterns of sub-adult bears could have been associated with a higher tolerance towards humans (MacHutchon et al., 1998;Zarzo-Arias et al., 2018) and/or with the efforts to avoid intra-specific competition over food sources (Kaczensky et al., 2006), which may be monopolized by adults at night (Klinka & Reimchen, 2002), when human activity is lower. ...
Article
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The survival of large carnivores in a rapidly changing, human-modified world depends largely on their movements; therefore, understanding how movement patterns change within space and time and which factors affect them most is of paramount importance for their conservation. In a case study in Greece using Brown bears Ursus arctos, we evaluated the movement ecology of a recovering population in a Mediterranean landscape, where human activity is high. We found that during daytime bears moved less when ambient temperatures were high and when they were far away from forests and close to settlements, where human activity is expected to be high. During night-time, when human activity and mortality risk are expected to be low, bear movement was higher farther from forested areas, close to roads, and in less rough terrain. Although bear movement patterns in Greece were generally similar to those of other bear populations in Europe, home ranges were smaller than in northern populations. These findings indicate that increased human activity and high ambient temperatures reduce bear movement and ultimately contribute to the smaller home ranges in the warmer and human-dominated Mediterranean landscapes. We suggest that management and conservation actions in Mediterranean landscapes should aim on separating humans and bears in space or time, so that bear movements are not constrained and, in turn, minimum home ranges that cover their essential requirements are guaranteed.
... Bears have well-developed external ears with moderately stiff pinnal flanges and are assumed to have good hearing across species. American black and brown bears appear to use auditory cues in salmon streams (Klinka and Reimchen 2002). Polar bears can hear well in air the relatively low frequencies of vocalization produced by seals, their prey (Owen et al. 2016). ...
... Bears appear to be quite "manual" and use their paws for foraging and manipulating food, exploring, and marking. Both American black bears and brown bears were observed to use tactile (and acoustical) cues when shifting from visually oriented foraging during the day to foraging in the darkness while fishing for salmon in forest streams (Klinka and Reimchen 2002). In addition to foraging, tactile senses are relevant to various social behaviors, orientation, and navigation. ...
Chapter
Entry available online: https://rd.springer.com/referenceworkentry/10.1007%2F978-3-319-47829-6_1745-1
... Fitness advantages for nocturnal behavior in diurnal species have been previously identified [26,27], and signal the importance of identifying diel behavior patterns rather than focusing on the dominant activity period. For example, the diurnal yellow breasted chat (Icterina virens) will move outside of their territories at night with fertile females engaging in extrapair copulations, potentially allowing them to go undetected by their social mate [26]. ...
... For example, the diurnal yellow breasted chat (Icterina virens) will move outside of their territories at night with fertile females engaging in extrapair copulations, potentially allowing them to go undetected by their social mate [26]. While being primarily diurnal, brown bears (Ursus arctos) forage equally between daylight and darkness during salmon migrations, with capture success increasing during the night [27]. Restricting data collection for diurnal species to expected daytime activity periods might hinder or limit our ability to gain further insight into important aspects of the biology and ecology of wildlife species. ...
Article
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Wildlife activity patterns tend to be defined by terms such as diurnal and nocturnal that might not fully depict the complexity of a species' life history strategy and behavior in a given system. These activity pattern categories often influence the methodological approaches employed, including the temporal period of study (daylight or nighttime). We evaluated banded mongoose (Mungos mungo) behavior in Northern Botswana through the use of remote sensing cameras at active den sites in order to characterize early morning behavior for this diurnal species. Our approach, however, provided the facility to capture unexpected nocturnal activity in a species that had otherwise only been studied during daylight hours. Camera traps were deployed for 215 trap days (24 hour data capture period) at den sites, capturing 5,472 photos over all events. Nocturnal activity was identified in 3% of trap days at study den sites with both vigilant and non-vigilant nocturnal behaviors identified. While vigilant behaviors involved troop fleeing responses, observations of non-vigilant behaviors suggest nonresident mongoose may investigate den sites of other troops during nocturnal time periods. There was no association between the occurrence of nocturnal activity and lunar phase (Fisher's exact test, n = 215, p = 0.638) and thus, increased moonlight was not identified as a factor influencing nocturnal behavior. The drivers and fitness consequences of these nocturnal activities remain uncertain and present intriguing areas for future research. Our findings highlight the need for ecological studies to more explicitly address and evaluate the potential for temporal variability in activity periods. Modifying our approach and embracing variation in wildlife activity patterns might provide new insights into the interaction between ecological phenomenon and species biology that spans the diurnal-nocturnal spectrum.
... Research suggests that brown bears' ability to successfully capture salmon may vary based on environment and visibility. For example, in the clear-water Glendale River in British Columbia, Klinka and Reimchen (2002) found a marginal trend of increased capture efficiency with reduced light levels, which they suggest is due to reduced evasive behavior of salmon at night. Crupi (2003), however, found that in the glacially turbid Chilkoot watershed in Southeast Alaska, bears had increased capture efficiency with increased light levels, due to better visual detection of salmon during daylight. ...
... Limitation to nocturnal foraging opportunities may influence non-habituated bears' ability to maintain adequate food intake. While one previous study found a marginal trend of increased salmon capture efficiency with reduced daylight levels in a clear-water river (Klinka and Reimchen 2002), a study of bear foraging success on salmon spawning grounds in the glacially turbid Chilkoot watershed between 2000 and 2002 found that bears' capture rates of salmon decreased significantly with diminishing daylight and increased significantly with increasing daylight, likely due to better visual detection of salmon during daylight hours (Crupi 2003). These findings suggest that in this system, temporal displacement of nonhabituated bears by human activity may have a detrimental effect on bears' foraging success, while habituation releases bears from fear-based effects of human presence and thus improves foraging opportunities for habituated individuals. ...
Article
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Fear induced by human activity is increasingly becoming recognized to influence both behavior and population biology of wildlife. Exposure to human activity can cause animals to avoid human-dominated areas or shift temporal activity patterns, but repeated, benign exposure can also result in habituation of individuals. Habituation is typically viewed as a negative potential consequence of human interactions with wildlife, with effects such as increased vulnerability of habituated animals to predation. Concurrently, the advancement of the understanding of the ecology of fear has shown reduced fitness in species because of behavioral changes in responses to fear of predators—including humans. Here, we test how habituation and fear drive the foraging ecology of brown bears (Ursus arctos) feeding on Pacific salmon (Oncorhynchus spp.) in Southeast Alaska, USA. We used motion-detecting trail cameras at salmon spawning areas across a gradient of human disturbance to record human and bear activity at fine spatial and extended temporal scales. Higher human activity was associated with increased nocturnality of non-habituated bears, likely leading to suboptimal foraging, but had no effect on habituated individuals. For the top 20% of sites for which human activity was greatest, an average of 78.7% of the activity of non-habituated bears was nocturnal, compared with an average of only 10.2% of the activity of habituated individuals. Habituation of brown bears in this system alleviated perceived risk and avoidance of human activity, allowing habituated individuals to overcome their fear of human presence and maximize foraging opportunities. While habituation may lessen some of the deleterious effects of human activity on large carnivores, the long-term effects of habituation may be negative, as habituated individuals may be at greater risk of depredation. Future research should examine whether habituated bears and their lower perceived risk of human activity ultimately experience smaller population-level effects of human disturbance than non-habituated individuals.
... Past persecution in Europe (Treves and Karanth 2003) and current human disturbance are among the main factors explaining some of the behavioural differences observed between bear populations living in the old continent and those living in more pristine areas of North America (Woodroffe 2000;Munro et al. 2006;Martin et al. 2010;Ordiz et al. 2013Ordiz et al. , 2014. This can be observed by the combined adoption of space use patterns aimed at minimizing human-related disturbance and more nocturnal activity patterns compared to North American grizzlies (Klinka and Reimchen 2002;Kaczensky et al. 2006;Munro et al. 2006). Human-induced changes are sometimes observable even within the same population range, with bears adapting both space use and activity patterns. ...
Thesis
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Space is one of the most disputed resources between humans and other wildlife species in modern human-dominated landscapes. Successful wildlife management and conservation requires a deep understanding of the interactions between a species and the space where it lives, including direct and indirect effects of both natural and human-related factors of fundamental ecological processes. The high spatio-temporal resolution of Global Positioning System (GPS) tracking data turns tagged animals into in situ sensors of the environment, and allows investigating how environmental changes affect species’ distribution and ecological function. Large carnivores, in particular, with their wide movement ranges and large spatial requirements are highly susceptible to disturbance from infrastructure development; as such, they can represent an ideal case study to investigate the effects of expansion of human activities on species’ spatial ecology at multiple levels, spanning from patch to landscape scales. In this thesis, I investigated space-use patterns of a south-eastern European population of brown bears (Ursus arctos), whose distribution is shared among more than five countries, from Slovenia to Northern Greece, with its core between Slovenia and Croatia. Despite being the third largest brown bear population in Europe, only few studies have focussed on the spatial ecology of the Dinaric-Pindos bear population. I investigated how environmental factors and proxies of human activities (e.g., roads, human settlements, hunting sites) influenced patterns of bear space use, movements and habitat selection. I used this knowledge to develop a movement-based modelling approach, aimed at mapping patch connectivity for seasonal movements of bears within the study area. In addition to enhancing our knowledge of bear ecology at broader scale across Europe, the results from this thesis are also of practical value, as they inform current and future management and conservation scenarios in the light of ongoing development projects throughout the countries inhabited by the study population.
... Alternatively, diurnal movement may provide easier accessibility to food sources which are occupied by other bears during the night. This assumption is in accordance with findings by Klinka and Reimchen (2002) and Kaczensky et al. (2006), who suggest that diurnal activity of females with offspring can be advantageous in relation to food accessibility and offspring safety. We found a significant increase in movement rates of females with dependent offspring for all periods of the day during hyperphagia, which is possibly related to increased mobility and nutritional needs of offspring. ...
Article
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Most animals concentrate their movement into certain hours of the day depending on drivers such as photoperiod, ambient temperature, inter- or intraspecific competition, and predation risk. The main activity periods of many mammal species, especially in human-dominated landscapes, are commonly set at dusk, dawn, and during nighttime hours. Large carnivores, such as brown bears, often display great flexibility in diel movement patterns throughout their range, and even within populations, striking between individual differences in movement have been demonstrated. Here, we evaluated how seasonality and reproductive class affected diel movement patterns of brown bears of the Dinaric-Pindos and Carpathian bear populations in Serbia. We analyzed the movement distances and general probability of movement of 13 brown bears (8 males and 5 females) equipped with GPS collars and monitored over 1–3 years. Our analyses revealed that movement distances and probability of bear movement differed between seasons (mating versus hyperphagia) and reproductive classes. Adult males, solitary females, and subadult males showed a crepuscular movement pattern. Compared with other reproductive classes, females with offspring were moving significantly less during crepuscular hours and during the night, particularly during the mating season, suggesting temporal niche partitioning among different reproductive classes. Adult males, solitary females, and in particular subadult males traveled greater hourly distances during the mating season in May-June than the hyperphagia in July–October. Subadult males significantly decreased their movement from the mating season to hyperphagia, whereas females with offspring exhibited an opposite pattern with almost doubling their movement from the mating to hyperphagia season. Our results provide insights into how seasonality and reproductive class drive intrapopulation differences in movement distances and probability of movement in a recovering, to date little studied, brown bear population in southeastern Europe.
... In the present study, brown bears were mostly recorded by camera traps during the daytime, indicating that they are diurnal predators of cicada nymphs (Fig. 4a). The diel patterns of brown bear foraging activities are usually diverse (Klinka and Reimchen, 2002;Munro et al., 2006). Given that brown bears are active throughout the day (Ikeda et al., 2016;Kaczensky et al., 2006), they would divide their activity time during the day according to the type of food item and foraging behavior (Munro et al., 2006). ...
Article
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Cicadas, a group of large-bodied insects, are preyed upon at both nymphal and adult stages by diverse range of vertebrates such as birds and mammals. Although the behavior of predators toward adult cicadas is well documented, there is a lack of research on the predation on cicada nymphs. In this study, camera traps deployed in conifer plantations, in which high population densities of cicadas Lyristes bihamatus emerge, were used to evaluate the seasonal and diel patterns of predation upon cicada nymphs by three predator species, namely brown bears, red foxes, and jungle crows, from May to September in 2018 and 2019 in northern Japan. Among all three species, cicada nymph predation occurred until early August when the final instar nymphs fully emerged. Bears were observed to constantly dig for cicada nymphs until early August, whereas foxes and crows were frequently observed foraging from late July to early August, during the season of L. bihamatus emergence. In contract to the powerful digging ability of bears, which facilitates efficient predation upon subterranean cicada nymphs, it is generally difficult for foxes and crows with limited or no digging ability to gain access these nymphs until the period of emergence. Cicada nymph predation by bears and crows was observed primarily during the daytime, despite the typical crepuscular/nocturnal emergence schedules of these insects. Contrastingly, the predatory activities of foxes tended to be nocturnal during the period prior to the beginning of cicada emergence, although subsequently became diurnal during the cicada emergence period. These observations indicate that the temporal activity patterns of cicada nymph predators are determined by interspecific differences in predation abilities and cicada emergence schedules. Accordingly, the findings of this study provide evidence to indicate that the timing and duration of trophic interactions between above- and belowground communities might vary among predator species, depending on their predation abilities.
... keta) per hour (Gill and Helfield 2012). In British Columbia, brown bears on the Glendale River averaged 3.9 fish per hour (Klinka and Reimchen 2002), and black bears on Riordan Creek averaged 1.9 fish per hour (Klinka and Reimchen 2009). These studies, however, did not indicate how long it took bears to eat individual salmon. ...
Article
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Detection, pursuit, capture, and consumption of prey by predators may be time consuming or not, depending on predators and prey, and this time allocation affects other aspects of predator ecology. Pacific salmon contribute substantially to coastal brown bear (Ursus arctos) diets, with implications for predators, prey, and their ecosystem. Brown bears were observed capturing sockeye salmon (Oncorhynchus nerka) at Mikfik Creek, Alaska, to determine capture and consumption rates. Bears averaged 3:00 min (SD = 5:24) to capture and 2:26 min (SD = 1:33) to completely consume small adult sockeye salmon. These foraging activities thus occupied only a small fraction of their total time budget at this site.
... The reduction of home ranges during diurnal hours compared with nocturnal hours likely is attributable to the higher nocturnal activity levels observed among bears of the Dinaric-Pindos region (Kaczensky et al. 2006;Smith 2018) and in other bear populations in Europe (Moe et al. 2007;Ordiz et al. 2014). Space-use patterns that buffer human-related disturbance and the higher nocturnality seem to be the main spatiotemporal adjustments adopted by bears in European human-dominated landscapes (Klinka and Reimchen 2002;Kaczensky et al. 2006;Munro et al. 2006). Past persecution in Europe (Treves and Karanth 2003) and current levels of human disturbance might explain the behavioral differences observed between bear populations in Europe and those living in the more pristine areas of North America (Woodroffe 2000;Munro et al. 2006;Martin et al. 2010;Ordiz et al. 2013Ordiz et al. , 2014. ...
Article
Studying how animals interact with their environment is fundamental to informing conservation and management efforts, especially when examining large, wide-ranging carnivores in human-dominated landscapes. We hypothesized that the home ranges of bears are configured to exploit supplemental food (corn) and avoid people. In 2004–2016, we tracked 10 brown bears from the Dinaric-Pindos population using GPS telemetry, then used Brownian bridge movement models to estimate their home ranges. We related seasonal home range size to circadian period and density of supplemental feeding sites using generalized linear mixed-effect models. We also used ecological-niche factor analysis to study habitat composition within home range core areas in study areas characterized by different levels of human encroachment. We found that home range size was inversely related to density of supplemental feeding sites, and bears had larger home ranges at night (x̅ = 103.3 ± 72.8 km2) than during the day (x̅ = 62.3 ± 16.6 km2). Our results also revealed that bears living in more human-influenced areas concentrated their use far from human settlements and agricultural lands but stayed close to supplemental feeding sites. Our data suggest that bears alter their space-use patterns at the home range level in response to anthropogenic land use and food availability.
... Indeed, this predominantly "shy" behaviour is typical of carnivores, which show diurnal activity in remote areas and often become more nocturnal when in human-dominated landscapes (Ordiz et al., 2017). In North America, for example, where areas inhabited by bears are generally characterized by low intensity of human utilization, brown bears seem largely diurnal (Klinka and Reimchen, 2002) and more aggressive than their European counterparts (Swenson et al., 1999). ...
Article
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The preservation of large carnivores is a formidable challenge for biodiversity conservation in Europe, where few areas can be considered wilderness. In this context, brown bears Ursus arctos in Europe coexist with people in densely settled, multi-use landscapes and hence have to cope with diffuse human activities. This calls for robust knowledge on the effects that such activities have on brown bear distribution and behaviour. We sampled 220 km2 with 60 camera trap locations over four consecutive years to investigate the effect of human activity and settlements on brown bear spatial and temporal patterns across the core area of the reintroduced population in the central Italian Alps. By using images of people and vehicles to quantify human activity at camera trap sites we could directly study how humans affect bears’ activity and occupancy. We assessed bear’s daily patterns and found a predominantly crepuscular and nocturnal behaviour, with peaks of activity before dawn and after dusk. We also modelled bear occurrence and detection probability around the dawn and dusk hours only, i.e., when the likelihood of encounters with humans was highest. Results showed that proximity to settlements and anthropogenic traffic, especially motorised, significantly and negatively influenced bear occupancy rates across the study area. Pedestrian and motorised traffic rates were both also negatively related to detection probability. By using four years of data and a refined modelling approach that considered the hours of maximum activity overlap of humans and bears, our results extend the findings from an initial study by suggesting that human presence induces not only temporal, but also spatial displacement. These findings are consistent with evidence from other populations that bears living in human-modified landscapes adapt their spatio-temporal patterns to avoid humans, an important prerequisite for the coexistence of bears and people in complex human-natural landscapes.
... Peak hour of activity fluctuated from midday during spring and fall to evening during summer. In coastal British Columbia, Klinka and Reimchen (2002) found that brown bears showed slightly greater efficiency catching salmon with reduced light levels, leading to substantial nocturnal activity. There is also evidence that diel activity patterns and movements can be impacted by human activities, including traffic volumes, such that brown bears become more active at night (Gibeau et al. 2002;Graves et al. 2006;Schwartz et al. 2010a;Northrup et al. 2012b;Kite et al. 2016;Ladle et al. 2019). ...
Chapter
Bears have fascinated people since ancient times. The relationship between bears and humans dates back thousands of years, during which time we have also competed with bears for shelter and food. In modern times, bears have come under pressure through encroachment on their habitats, climate change, and illegal trade in their body parts, including the Asian bear bile market. The IUCN lists six bears as vulnerable or endangered, and even the least concern species, such as the brown bear, are at risk of extirpation in certain countries. The poaching and international trade of these most threatened populations are prohibited, but still ongoing. Covering all bears species worldwide, this beautifully illustrated volume brings together the contributions of 200 international bear experts on the ecology, conservation status, and management of the Ursidae family. It reveals the fascinating long history of interactions between humans and bears and the threats affecting these charismatic species.
... These decisions produce circadian patterns in behavior driven by daily cycles in habitat variables such as light, temperature, and food availability, but also affected by factors such as habitat quality, competition, and individual state. Such cycles have been observed throughout the animal kingdom, including in insects (Whitford and Ettershank 1975), birds (Holmes et al. 1978;Brandt and Cresswell 2009), small (Levy et al. 2016) and large mammals (Klinka and Reimchen 2002), marine fish (Strand and Huse 2007), and the salmonid fish we model (Metcalfe et al. 1998(Metcalfe et al. , 1999. ...
Article
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Many animals make contingent decisions, such as when and where to feed, as trade-offs between growth and risk when these vary not only with activity and location but also 1) in cycles such as the daily light cycle and 2) with feedbacks due to competition. Theory can assume an individual decides whether and where to feed, at any point in the light cycle and under any new conditions, by predicting future conditions and maximizing an approximate measure of future fitness. We develop four such theories for stream trout and evaluate them by their ability to reproduce, in an individual-based model, seven patterns observed in real trout. The patterns concern how feeding in four circadian phases—dawn, day, dusk, and night—varies with predation risk, food availability, temperature, trout density, physical habitat, day length, and circadian cycles in food availability. We found that theory must consider the full circadian cycle: decisions at one phase must consider what happens in other phases. Three theories that do so could reproduce almost all the patterns, and their ability to let individuals adapt decisions over time produced higher average fitness than any fixed behavior cycle. Because individuals could adapt by selecting among habitat patches as well as activity, multiple behaviors produced similar fitness. Our most successful theories base selection of habitat and activity at each phase on memory of survival probabilities and growth rates experienced 1) in the three previous phases of the current day or 2) in each phase of several previous days.
... Bears might more often contact wires at night than during the day, when wires are presumably easier to see. Bears can forage on salmon successfully at night, but sub-adults and females with cubs may avoid nocturnal foraging because of the threat posed by socially dominant and potentially infanticidal adult males (Klinka and Reimchen 2002). By implication, subordinate individuals and females with young may be hyper-vigilant at night and less likely to make contact with wires. ...
Article
Studies of the movements and abundance of predators can reveal their ecological roles and facilitate their conservation. These studies rely increasingly on noninvasive methods such as hair collection and camera traps. Insights from hair sampling, however, may be compromised if collection devices elicit avoidance behavior. To determine the extent to which brown bears Ursus arctos avoided barbed wire deployed to collect hair samples, we paired two wires on each of six small streams with motion-activated video recorders in the Wood River system, southwestern Alaska, where bears prey on sockeye salmon Oncorhynchus nerka. Of 350 videos showing a bear approaching the wire with an unambiguous result, the bear contacted the wire in 80.9% and avoided it 19.1% of the approaches. Females more often avoided the wire than did males (39% versus 20%), and bears more frequently avoided the wire at night (23.6%) than during daytime (10.8%) and crepuscular (19.1%) periods. Other comparisons (bears in groups versus single bears, and adults versus cubs) were not significantly different. The high proportion of approaches that led to contact with the wire indicates that this hair-sampling method is generally successful. Our findings also suggest, however, that interpretation of data obtained from such sampling should consider the possibility of biases with respect to sex and time of day.
... Prey species may be less able to detect or avoid predators at night. For example, the observed prey capture efficiency of brown bears was 16% higher at night, which was attributed to decreased evasion behavior of salmon (Klinka and Reimchen 2002). Some prey species may be more accessible to predators at nighttime. ...
... Time-activity budgets are the foundation of many behavioural studies (Altmann, 1974), providing valuable information about how individuals allocate their time, and potentially energy, and how these patterns may change over time, across populations or among individuals in relation to sex, age, status, social context, topography, thermal environment (e.g., Anderson & Harwood, 1985;Isbell & Young, 1993;Klinka & Reimchen, 2002;Twiss et al., 2002), and more recently the impacts of anthropogenic activity (e.g., Bayne et al., 2008;Christiansen et al., 2013;Bishop et al., 2015). Activity budgets are typically generated from direct visual observation, however, such observations are often limited to daylight periods, therefore many activity budgets relate to diurnal activity only, or assumptions are made about nocturnal activity (e.g., diurnal species may be assumed to rest at night). ...
Article
Time-activity budgets are fundamental to behavioural studies, allowing examination of how individuals allocate their time, and potentially energy, and how these patterns vary spatially and temporally and in relation to habitat, individual identity, sex, social status and levels of anthropogenic disturbance. Direct observations of animal behaviour, especially in the wild, are often limited to daylight hours; therefore, many activity budgets relate to diurnal activity only, or assumptions are made about nocturnal activity. Activity budgets have been a key component of many behavioural and energetics studies of breeding grey seals ( Halichoerus grypus , Fabricius, 1791), and yet very little is known about nocturnal activity of grey seals, and a general, implicit assumption of no significant change from day to night seems to pervade the literature. Here we use a combination of high resolution digital video and thermal imaging video camera to follow known individual grey seal mothers from day into night to examine activity patterns during lactation. We show distinct differences in nocturnal activity budgets relative to diurnal activity budgets. Mothers spent significantly more time resting with a reduction of time spent in the alert and comfort move behavioural categories during nocturnal periods. It is clear that diurnal time-activity patterns of breeding female grey seals cannot be extrapolated to represent activity across a 24-hour cycle. These considerations are particularly critical in studies that aim to use time-activity budgets as proxies for energy budgets.
... The bear has been subjected to various genetic and ecological studies on its origin, structure and behaviour (Klinka, D. R. and Reimchen, T. E., 2002;Pàges, M., 2008). In our country there are little scientific reports that are related to clinical cases and the bear has been treated (Manov, V. et al., 2013;Aminkov, B. et al., 2017;Aminkov, B. et al., 2018) and more one popular book on subject (Gunchev R., 1994). ...
Article
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Histological investigation and functional comment of the brown bear stomach structure wall and its comparison with another carnivorous as dog, fox, wolf, jackal, cat and tiger, respectively which were surveyed previously was the aim of this study. The stomach of a female brown bear after sudden death was obtained and slides by conventional histological method were examined microscopically and morphometry was done. In mucosal layer of the brown bear stomach as in other investigated canine species the subglandular layer stratum compactum was not established also, as opposed to feline species in which stomach's mucosa this specific collagenous layer was always presented.
... My results are consistent with those obtained by Jerina et al. (2012) and Dolšak (2015), who already observed that bears are following a specific pattern of approach to feeding sites, where females and cubs approached them earlier in the day (around dusk and dawn hours) whereas males approached them at night. This pattern also seems to be respected in approaching other clumped food resources (Klinka and Reimchen 2002), in selecting home-ranges (Steyaert et al. 2013a) and in avoiding humans and/or other animals (Olson et al. 1998, Kaczensky et al. 2006. Kaczensky et al. (2006) proposed that the mechanism of avoidance is learned and this is the reason why it presents high inter-individual variation: cubs and younger individuals are more diurnal than the adults because they have not learned how humans can be dangerous yet. ...
Thesis
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One of the most important issues in the study of animal behaviour and ecology is how the spatial distribution of resources affects the home range and the spatial distribution of animals. When animals decide which resources they will use and where they will search for them, they must evaluate both the benefits and the costs of the available options. The benefits depend on the quality of the resources (the expected energy intake), whereas the costs depend on their handling time and on their associated predation risks. Such risks affect foraging decisions not only of low-trophic level species, but also those of large predators, such as the brown bear. In this species, in fact, animals must face two types of predation risks: firstly, humans, who hunt them, and, secondly, the other conspecifics, in particular males, who attack females with cubs in the attempt to kill the latter. In this study, we analyse how these factors of risk affect the foraging behaviour of brown bears. The study was carried out in the “Core Bear Protective Area”, in South Slovenia, a region where the animals live at a high density, but where they experience strong human impact. In this area, hunters have and manage different feeding sites, created for diversionary feeding purposes, but they are also used for hunting. Eighteen of these feeding sites were monitored with camera traps for 2 consecutive years. The feeding sites were supplied either with corn or with carrions, swapping the bait between the two years. Slovenian hunters took care of all feeding sites and camera traps and they regularly delivered us the SD cards of the camera traps. Pictures and videos were analysed one by one. For each observation, we recorded into an Excel file the number and the sex of the observed individuals, and we added the hour, the day, the name of the feeding site and other information, such as the type of bait used and bear density (number of individuals per squared kilometre). Each observation was classified into two categories, depending on whether it included cubs (with females) or other animals (either males or females, but without cubs). To test the hypothesis that the different predation risk faced by the two categories of individuals forced them to use the feeding sites in a different way, we analysed the relationship between the type of observations (dependent binary variable) and a set of predictors (independent variables), using generalized linear mixed models (GLMM). Specifically, we considered as independent factors the hour of observations, the season, the type of bait used and the bear density in the area around the feeding site. Results showed that females with cubs visited the feeding sites mostly at dawn and at dusk, whereas bears without cubs were observed mostly in the mid of the night. These differences in feeding activity were larger during mating season, when the risk of infanticide was higher. Moreover, females with cubs were more likely to be observed at the feeding sites supplied with corn rather than at those supplied with carrion. However, the probability of observing females with cubs did not appear to be affected by bear density at the feeding sites. Overall these results suggest that bears visited the feeding sites during the night, when the risk of bumping into humans was low. Since females with cubs had to trade off the risk of encountering humans with the risk of encountering dangerously aggressive males, they concentrated the activity at the feeding sites when both the types of risk were relatively low, that is, just after dusk and just before dawn. These findings showed how wildlife management strategies had a strong impact on the social behaviour of brown bears.
... There is growing evidence that brown bears exhibit optimal foraging strategies for salmon both within streams (Cunningham, Ruggerone, & Quinn, 2013;Gende, Quinn, Hilborn, Hendry, & Dickerson, 2004;Klinka & Reimchen, 2002) and across large landscapes (Deacy, Leacock, Armstrong, & Stanford, 2016). Accordingly, under the hypothesis that individual bears have knowledge of foraging opportunities across the landscape and respond to differences in salmon densities in a manner that optimizes energy intake rate, we predicted that most individuals would: (a) use only one stream neighborhood during a spawning season (summer) because of the energetic costs associated with swimming across or traveling around the lake; and (b) show fidelity to stream neighborhoods across years because of the presumed benefits of familiarity with local salmon dynamics (e.g., run timing) and stream characteristics (e.g., prime fishing areas) (Edwards, Nagy, & Derocher, 2009;Part, 1995). ...
Article
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The interaction between brown bears (Ursus arctos) and Pacific salmon (Oncorhynchus spp.) is important to the population dynamics of both species and a celebrated example of consumer‐mediated nutrient transport. Yet, much of the site‐specific information we have about the bears in this relationship comes from observations at a few highly visible but unrepresentative locations and a small number of radio‐telemetry studies. Consequently, our understanding of brown bear abundance and behavior at more cryptic locations where they commonly feed on salmon, including small spawning streams, remains limited. We employed a noninvasive genetic approach (barbed wire hair snares) over four summers (2012–2015) to document patterns of brown bear abundance and movement among six spawning streams for sockeye salmon, O. nerka, in southwestern Alaska. The streams were grouped into two trios on opposite sides of Lake Aleknagik. Thus, we predicted that most bears would forage within only one trio during the spawning season because of the energetic costs associated with swimming between them or traveling around the lake and show fidelity to particular trios across years because of the benefits of familiarity with local salmon dynamics and stream characteristics. Huggins closed‐capture models based on encounter histories from genotyped hair samples revealed that as many as 41 individuals visited single streams during the annual 6‐week sampling season. Bears also moved freely among trios of streams but rarely moved between these putative foraging neighborhoods, either during or between years. By implication, even small salmon spawning streams can serve as important resources for brown bears, and consistent use of stream neighborhoods by certain bears may play an important role in spatially structuring coastal bear populations. Our findings also underscore the efficacy of noninvasive hair snagging and genetic analysis for examining bear abundance and movements at relatively fine spatial and temporal scales.
... Direct observation is one way to measure encounter and handling times of prey (Stirling 1974;Klinka and Reimchen 2002). For example, observers can follow predators in the field to document the time between predation events (Miller et al. 2013). ...
Article
The foraging patterns and behaviors of predators can be discerned using GPS data. We used GPS data to investigate the temporal patterns of wolverine (Gulo gulo luscus) foraging on large prey in northern Alberta. We built a predictive model of wolverine large-prey events (beaver predation or ungulate scavenging) based on the spatial and temporal patterns of wolverine GPS data at foraging sites we visited in the field in winter. We used this model to predict large-prey events throughout our entire wolverine GPS dataset in winter and summer. We then evaluated how variables related to prey availability, seasonality, competition, and territoriality affected wolverine encounter time, residency time, and return time at predicted large-prey events. We found that wolverines encountered large prey more often in the spring when there is increased beaver and ungulate availability. The total time that wolverines spent at large-prey events was greater in winter (3.11 days [95th percentile = 2.62-3.63 days]) than summer (2.08 days [95th percentile = 1.70-2.51 days]), potentially because prey availability is limited in winter or prey is easier to capture in summer. Wolverines partitioned the total time at events into multiple visits, reducing their residency time and increasing their return time with each revisit, indicating biomass decline through time. The time between visits in winter (10.12 days [95th percentile = 7.99-12.56 days]) and summer (8.39 days [95th percentile = 7.18-9.74 days]) suggests wolverines might be patrolling their home range. We also found that wolverine residency time decreased and return time increased when there were other large-prey events available. Moreover, wolverine residency time at events increased when other wolverines were in the area. Our results suggest that large-prey events are important to the energy balance of wolverines and that wolverine foraging behavior is dynamic in response to environmental change.
... Due to this flexibility, species that subsist in variable systems can achieve greater population densities across a larger geographic range (Hutchinson 1957). Ecological plasticity within a population can be attributed to variations in abiotic factors (Hiesey 1953;Cook and Johnson 1968), interspecific and intraspecific competition (Marshall and Jain 1969;Relyea 2001), and dominance hierarchies (Klinka and Reimchen 2002). One of the most common manifestations of ecological flexibility is through behavior (Gordon 1991). ...
Article
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Behavioral differences within a population can allow use of a greater range of resources among individuals. The brown bear (Ursus arctos) is a generalist omnivore that occupies diverse habitats and displays considerable plasticity in food use. We evaluated whether brown bear foraging that resulted in deviations from a proposed optimal diet influenced body condition and, in turn, denning duration in Lake Clark National Park and Preserve, Alaska. To assess assimilated diet, we used sectioned guard hair samples (n = 23) collected in autumn to determine stable carbon and nitrogen isotope ratios. To index proportional contributions of meat and vegetation to assimilated diets, we compared the carbon (δ¹³C) and nitrogen (δ¹⁵N) values of hair samples with the values identified for major food categories. We then compared percentage body fat and body mass in relation to the proportion of assimilated meat in the diet using linear models. We also examined the influence of autumn percentage body fat and mass on denning duration. Percentage body fat was not influenced by the proportion of assimilated meat in the diet. Additionally, percentage body fat and body mass did not influence denning duration. However, body mass of bears assimilating proportionately more meat was greater than bears assimilating less meat. Our results provide support for previous findings that larger bears consume higher amounts of protein to maintain their body size and therefore forage further from the proposed optimal diet. Additionally, our results demonstrate that individuals can achieve similar biological outcomes (e.g., percentage body fat) despite variable foraging strategies, suggesting that individuals within generalist populations may confer an adaptive advantage through behavioral plasticity.
... Nocturnal foragers experience a sensory environment that is distinct from the context faced by their diurnal counter-parts (Klinka & Reimchen, 2009). Diurnal foragers, for example, are typically able to rely on visual cues (Dominy hunters are successful visual predators (Nekaris, 2005;Piep et al., 2008;Martin, 2012), in the absence of sunlight visual cues often become less useful than those available through other sensory means and their utility is often reliant on prey movement (Barton et al., 1995;Klinka & Reimchen, 2002). For nocturnal species therefore, non-visual means of prey detection are often not only their preferred modalities but are also more effective in detection of prey items over distance Jones, 2013). ...
Article
In the absence of direct sunlight, nocturnal animals face sensory challenges different to those affecting their diurnal counterparts whilst foraging. Anecdotal observations have led to the general prediction that the auditory sensory mode is the most prominent for the bat-eared fox (Otocyon megalotis), a nocturnal, insectivorous canid. The present study aimed to clarify the relative importance of different sensory modes to foraging bat-eared foxes by conducting sensory trials with individuals belonging to a habituated population in the Kuruman River Reserve in South Africa. Foxes were tested in repeated trials controlling for particular sensory stimuli using live or pre-killed prey. Auditory cues proved significant (p≤0.01) predictors of fox foraging success with olfactory and visual cues indicated as being of secondary importance. This study thus provides empirical confirmation for anecdotal reports that the bat-eared fox is predominantly reliant on auditory cues to determine hunting success. © 2017
... Prey species may be less able to detect or avoid predators at night. For example, the observed prey capture efficiency of brown bears was 16% higher at night, which was attributed to decreased evasion behavior of salmon (Klinka and Reimchen 2002). Some prey species may be more accessible to predators at nighttime. ...
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It is commonly assumed that elasmobranchs (sharks, skates, and rays) are most active during dark periods (dawn, dusk, night). However, this assertion has not been critically evaluated. It is also unclear whether dark periods are primarily utilized for the performance of important life-history events, such as mating. If this were the case, low-light periods would be of significance to elasmobranch conservation as some anthropogenic activities (night fishing, lighting) could disproportionately impact fitness of species that are more active in the dark. Here, we review and summarize previous studies on elasmobranch behavior during nocturnal and crepuscular periods focusing on patterns of movement, habitat use, foraging, and reproduction. A review of 166 studies provided mixed results for widely-assumed increased elasmobranch activity when dark. Frequency of foraging and horizontal movement (distance travelled, activity space) were reported as greater only during crepuscular periods in the majority (>50%) of reviewed studies (28 of 43 and 78 of 125 studies, respectively), a pattern not evident during night. No pervasive patterns emerged for increased habitat use or reproductive behaviors during dark. We did not find any particular habitat type consistently supporting increased activity during dark, nor did we find evidence that higher trophic level elasmobranchs were more active when dark. Thus, generalizations about increased elasmobranch activity during dark periods are currently not supported. While research on the behavior of elasmobranchs during dark periods has been increasing, many knowledge gaps remain and we present a set of research priorities to assist in the development of future investigations.
... Activity patterns are a fundamental part of the species' natural history and represent a pivotal aspect of animal behavior (Enright 1970, Nielsen 1983. Activities of top predators are mainly influenced by prey, energy costs, environmental factors, and human activity, or a combination of these factors (Theuerkauf et al. 2003, Vila et al. 1995, Klinka & Reimchen 2002. In general, birds of prey tend to synchronize hunting activity with the activity of their prey, or with times when the prey are most vulnerable (Bechard 1982, Sarasola & Negro 2005. ...
... Because fitness can be difficult to measure directly, typically a proxy for fitness is used as a focal variable (a fitness "currency"), such as rate of energy gain (assumed to be maximized), time spent in gaining energy (minimized), or predation risk (minimized; Stephens and Krebs 1986). Because OFT most commonly predicts that foragers attempt to maximize their intake of energy (Charnov 1976, Stephens and Krebs 1986, Whelan and Schmidt 2007, many early bear studies have focused on energetic aspects of foraging and consumption rates (e.g., Bunnell and Hamilton 1983, Welch et al. 1997, Rode et al. 2001, Klinka and Reimchen 2002, Wilmers and Stahler 2002. Protein and food digestibility were also often considered in addition to energy in diet studies (Pritchard and Robbins 1990, McLellan and Hovey 1995, Hilderbrand et al. 1999a,b, Munro et al. 2006, Coogan et al. 2012), yet carbohydrate and lipid were mostly overlooked. ...
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Knowledge of carnivore nutritional requirements offers a potentially powerful aid for conservation and management strategies, yet has received little attention. We discuss how nutritional ecology, nutritional geometry, and the concept of macronutrient (protein, lipid, and carbohydrate) balance can be used to further our understanding of behavioral regulatory mechanisms that may influence food-related human–wildlife conflict, focusing on North American grizzly bears (Ursus arctos). We propose that the macronutrient preferences of omnivorous grizzly bears are a strong driver of their conflict with humans due to nutrient-specific foraging behavior, which we predict will be particularly noticeable during periods in which “key” natural foods high in lipid or carbohydrate are limiting. We demonstrate how nutritional geometry can be used to investigate the concept of nutrient balance by integrating recent research on the macronutrient selection of the grizzly bear with nutritional estimates of potentially consumed anthropogenic foods. Our geometric analysis utilizing right-angled mixture triangles suggested that anthropogenic foods offer grizzly bears nonprotein energy sources that may allow them to optimize macronutrient intake. This macronutrient-focused approach gives rise to fundamentally different predictions (and potentially management strategies) than the conventional food and energy-focused approaches. This article also provides insight into food-related conflict among other bear and carnivore species, and human–carnivore conflict more generally, by outlining a nutritionally explicit predictive framework for understanding the potentially volatile interface between anthropogenic environments and the behavior of wild animals.
... The correlations between the little raven abundance estimates for the wetland and the percentage of red-capped plover nests laid in each month, and also the percentage of false clutches surviving to 30 days, suggested that little ravens are aggregating at the wetlands to take advantage of the seasonally abundant prey resource of red-capped plover eggs. Some predators target seasonal or temporal increases in abundance of prey (food pulses), aggregating in areas where prey populations are seasonally abundant (Clua and Grosvalet 2001;Klinka and Reimchen 2002;Barnett and Semmens 2012;Ekanayake et al. 2015b). Corvids are notorious for their ability to exploit anthropogenic (e.g. ...
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Context Loss of eggs to predators is a major cause of reproductive failure among birds. It is especially pronounced among ground-nesting birds because their eggs are accessible to a wide range of predators. Few studies document the main causes of clutch fate of ground-nesting birds. Aims The main objective of the present study was to identify the major egg predator of red-capped plovers (Charadrius ruficapillus). We also investigated the effectiveness of the following two primary strategies available to the plovers to avoid egg predation: (1) the placement of clutches under vegetative cover and (2) avoiding predators by nesting outside the peak season of predator occurrence. Methods Remote-sensing cameras were deployed on plover nests to identify egg predators and nests were monitored over four breeding seasons to document reproductive success and fate. An experiment using false clutches with model eggs investigated the influence of nest cover on the risk of egg predation throughout the year. Line-transect surveys were conducted to estimate the abundance of egg predators in and around the wetlands. Key results The little raven (Corvus mellori) was the major egg predator identified in 78.6% of red-capped plover clutches and in 92.4% of false clutches that were camera-monitored. The hatching success of plover eggs was not influenced by nest cover (P≤0.36), but model egg survival in false clutches improved significantly with the presence of nest cover (P≤0.02). The abundance of little ravens increased during the plover breeding season and was highly negatively correlated with false clutch survival (rpearson≤-0.768, P≤0.005). Conclusions Little ravens were the major predator of red-capped plover eggs and their abundance increased significantly during the plover breeding season. Any influence of nest cover on hatching success of eggs may have been masked by the extremely high rate of egg loss associated with the increased little raven abundance during the plover breeding season. Implications The high rate of egg predation is likely to have negative consequences on the local red-capped plover population, suggesting management is warranted. Little raven populations have expanded and, thus, their impact as egg predators needs to be investigated especially on threatened species. Journal compilation
... Olson et al. (1998) also found that brown bears adapted a crepuscular activity pattern with a midday depression in activity when people were present. Furthermore, brown bears have been found to avoid people spatially and temporally when foraging for spawning fish (Reinhart andMattson 1990, Smith 2002) and can be highly successful foraging for spawning salmon in the dark (Klinka and Reimchen 2002). ...
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Anchorage, Alaska, has 301,000 human residents and hundreds of thousands of visitors each year. Anchorage also supports a viable population of brown bears (Ursus arctos). As a result, human-bear encounters are common. We used camera traps to monitor recreational trails near salmon spawning streams at 3 study sites during the summers of 2009 to 2012 to better understand daily and seasonal activity patterns of bears and humans on these trails. The more remote study sites had the least human activity and the most bear activity. Human-bear encounters were most likely to occur from July through early September due to a higher degree of overlap between human and bear activity during this timeframe. Most brown bears at our study sites appeared to have adopted a crepuscular and nocturnal activity pattern, which was more pronounced at the site with the most human use. More people used trails Friday through Sunday, while there was no difference in bear activity among other days of week. Recreational activities and user groups differed among sites. Based on our data, areas should be assessed individually to mitigate adverse human-bear encounters. However, a potential solution for avoiding dangerous bear encounters is to restrict human access or types of recreational activity. When human access is controlled in bear habitat, distribution of visitors becomes spatially and temporally more predictable, allowing bears an opportunity to adjust activity patterns to avoid people while still using the resource.
... Bear age, whether subadult or mature adult, was determined based on the presence of cubs (mature female), or size. Bears traveling alone and estimated to be larger than 250 kg, were classified as adult and smaller bears were classified as subadult (Klinka and Reimchen 2002). ...
Article
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All forms of recreation and tourism, including wildlife viewing, have the potential to alter wildlife habitat, behavior, survival, and/or reproductive success. The increasing number of visitors pursuing bear-viewing activities in coastal British Columbia, Canada, and Alaska, United States, has led to a number of studies assessing the impact of wildlife viewing on bear behavior. This study, the first to assess the impact of boat-based bear viewing in this region, used focal sampling to measure bear activity budgets in the absence and presence of nonresearch bear-viewing vessels. We found that: (1) some grizzly bears were clearly tolerant of wildlife viewing activities while others were not; (2) individual variation of bears' response to tourists was significant, introducing considerable uncertainty in attempting to assess medium- to long-term impacts of wildlife viewing; (3) males were rarely observed outside of the mating season, suggesting females (especially those with cubs) may use viewing areas as refuges from male grizzly bears; and (4) overt reaction distances varied greatly, suggesting that one appropriate management option may be to ensure boat captains can recognize potential displacement behavior in bears to avoid affecting subject animals. Some of the uncertainty arising from the biological research could be tempered by examining the social perspective of bear viewing tours to create an appropriate management plan for the K'tzim-a-deen Inlet Conservancy.
... Figura N°78: Efecto de los niveles de turbidez (NTU) sobre los rangos de ingesta de presas vivas en la trucha arco iris juvenil (Rowe et al., 2003). Además de las capacidades visuales anteriormente citadas y de las ya mencionadas en un capítulo previo, los salmónidos (Oncorhynchus) carecen de tapetum lucidum lo que reduce su capacidad visual a niveles muy bajos de luminosidad (Nicol et al., 1973;Klinka & Reimchen, 2009), por lo que deben confiar en su línea lateral, por ello lo osos costeros de British Columbia, Canadá, se alimentan extensivamente durante la noche de salmónidos, explotando la menor respuesta evasida desplegada por éstos en comparación con las horas de más luz (Reimchen, 1998a(Reimchen, ,b, 2000Klinka & Reimchen, 2002;Klinka, 2004;Klinka & Reimchen, 2009). En contranste con los salmónidos, los peces nocturnos y de aguas profundas no poseen conos el mosaico retinal (Engström, 1963;Sandy & Blaxter, 1980;Braekevelt, 1984Braekevelt, , 1994Evans & Browman, 2004). ...
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A review of the implications of the solar light intensity, polarization and ultraviolet radiation in salmonids, related to I.P. 44.321 in Chile. (Spanish version from 2009).
... Activity patterns are a fundamental part of the species' natural history and represent a pivotal aspect of animal behavior (Enright 1970, Nielsen 1983. Activities of top predators are mainly influenced by prey, energy costs, environmental factors, and human activity, or a combination of these factors (Theuerkauf et al. 2003, Vila et al. 1995, Klinka & Reimchen 2002. In general, birds of prey tend to synchronize hunting activity with the activity of their prey, or with times when the prey are most vulnerable (Bechard 1982, Sarasola & Negro 2005. ...
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Knowledge about activity patterns of raptors in forested areas is important to better understand their behavioral flexibility and adaptive ability. During nine months we survey the activity of Harris’s Hawks (Parabuteo unicinctus) for a total of 199 hours and 22 observation days in a coastal forested area of central Chile. The time spent in a particular activity was measured by using the focal-animal sampling method. Perching was the prevalent activity within each season and day. Harris’s Hawks perched more often during winter and autumn (83−95% of total time hawks were sighted), and flew more often during spring and summer (21.6−33.6% of total time hawks were sighted). Except in the winter, perching activity exhibited a bimodal pattern throughout the day. Harris’s Hawks were observed perching more often during mid-morning (09:00−11:00 h) and midday (12:00−14:00 h) in winter, during mid-morning and mid-afternoon (16:00−17:00 h) in spring and autum, and during mid-morning and late-afternoon (19:00−21:00 h) in summer. Six flight modes were identified including gliding, cruising, soaring, hovering, diving and parachuting. Soaring was the most observed flight mode throughout the year (46−87% of total time that they were observed flying (N = 10.5 hours). Within each season, time budgets of soaring differed markedly throughout the day. The Harris’s Hawk’s prevalent tendency to perch could be explained by its stereotyped sit-and-wait foraging mode. Perching behavior could also have conferred the advantage of access to the interior of forest remnants, and thereby, better exploitation of such prey patches. The prevalent use of soaring could be explained because it confers multiples advantages such as exploration, better detection of prey or intruders, territorial displays or courtship, and thermoregulation. Temporal variations in flight activities of Harris’s Hawks in our study site were consistent with concurrent climate and ecological conditions. The prevalent use of perching and diversified flight modes of Harris’s Hawks would confer them a greater adaptive ability in forested areas.
Article
The water–air interface is a globally widespread habitat for interactions between prey and predators. We experimentally manipulated water surface conditions (flat, smooth waves, three levels of current-induced turbulence) and digitally quantified the visual integrity of above-surface models from a subsurface perspective. Progressive fragmentation was present in each of the models (upright heron, crouched heron, vertical block, horizontal block) with increased departure from flat surface conditions. Smooth directional waves produced multiple horizontal bands (shadows) that moved across the models while surface currents distorted the profile, including progressive disintegration of the models appearance into multiple fragments of different sizes. This fragmentation is caused by scattered surface irregularities interacting with waves and is accentuated at the broken periphery of the optical window, reducing recognition of the models. Unexpectedly, we found that bands and fragments emerging from different surface conditions resemble common frontal plumage patterns on some Ardeidae and shorebirds (Charadriiformes). While these natural plumages are widely recognized to reflect a diversity of adaptations, including camouflage in terrestrial habitats, we suggest that their resemblance to water surface-induced fragmentation might also reflect foraging adaptations of predators though the water–air interface.
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Within optimal foraging theory animals should maximize their net energy gain while minimizing energetic costs. Energetic expenditure in wild animals is therefore key to measure proxies of fitness. Accelerometers are an effective tool to study animal movement-based energetics but retrieval of the device is usually required and often difficult. Measuring energetic expenditures using a global positioning system (GPS) approach could provide an alternative method to study energetic ecology. We compared accelerometer and GPS methods to estimate energetic expenditures in brown bears ( Ursus arctos ) on the Kodiak Archipelago, Alaska, USA. We then applied the GPS method to examine how intrinsic and extrinsic factors influenced brown bear movement-based daily energetic expenditures (MDEE). We predicted that bears would have greater energetic expenditures during the high food abundance period, while females with dependent young would have lower energetic expenditures due to reduced movements. We found that while the two energetic measurements differed (Wilcoxon signed rank test: V = 2116, p < 0.001), they were positively correlated ( r = 0.82, p < 0.001). The GPS method on average provided 1.6 times greater energy estimates than did the accelerometer method. Brown bears had lower MDEE during periods of high food abundance, supporting optimal foraging theory. Reproductive status and age did not influence MDEE, however movement rates had a positive linear relationship with MDEE. Energetic ecology is important for understanding drivers of animal movements. A GPS-derived estimate of energetic expenditure may be suitable when accelerometer data are unavailable, but the GPS-derived estimate should be validated for the specific taxa, ecosystem, and GPS sampling rate used. Additionally, while movement-based estimates of energy expenditure can elucidate the mechanisms driving habitat use decisions, they may not fully reflect an animal’s overall energy demands. Brown bear movement-based energetic expenditure was influenced by intrinsic and extrinsic factors which highlighted the importance of access to prime foraging sites to enhance energetic efficiency.
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Within optimal foraging theory animals should maximize their net energy gain while minimizing energetic costs. Energetic expenditure in wild animals is therefore key to measure proxies of fitness. Accelerometers are an effective tool to study animal movement-based energetics but retrieval of the device is usually required and often difficult. Measuring energetic expenditures using a global positioning system (GPS) approach could provide an alternative method to study energetic ecology. We compared accelerometer and GPS methods to estimate energetic expenditures in brown bears ( Ursus arctos ) on the Kodiak Archipelago, Alaska, USA. We then applied the GPS method to examine how intrinsic and extrinsic factors influenced brown bear movement-based daily energetic expenditures (MDEE). We predicted that bears would have greater energetic expenditures during the high food abundance period, while females with dependent young would have lower energetic expenditures due to reduced movements. We found that while the two energetic measurements differed (Wilcoxon signed rank test: V = 2116, p < 0.001), they were positively correlated ( r = 0.82, p < 0.001). The GPS method on average provided 1.6 times greater energy estimates than did the accelerometer method. Brown bears had lower MDEE during periods of high food abundance, supporting optimal foraging theory. Reproductive status and age did not influence MDEE, however movement rates had a positive linear relationship with MDEE. Energetic ecology is important for understanding drivers of animal movements. A GPS-derived estimate of energetic expenditure may be suitable when accelerometer data are unavailable, but the GPS-derived estimate should be validated for the specific taxa, ecosystem, and GPS sampling rate used. Additionally, while movement-based estimates of energy expenditure can elucidate the mechanisms driving habitat use decisions, they may not fully reflect an animal’s overall energy demands. Brown bear movement-based energetic expenditure was influenced by intrinsic and extrinsic factors which highlighted the importance of access to prime foraging sites to enhance energetic efficiency.
Chapter
Bears belong to the order Carnivora, suborder Caniformia. Caniformia means “doglike”. Their family is called Ursidae. Modern bears comprise eight species in three subfamilies: Ailuropodinae (monotypic with the giant panda), Tremarctinae (monotypic with the Andean spectacled bear), and Ursinae (containing six species: brown bear, American black bear, Polar bear, Asiatic black bear, sloth bear, sun bear). Bears’ closest living relatives are the pinnipeds, canids, and musteloids (Wesley-Hunt and Flynn 2005).
Chapter
Adventure tourism numbers are estimated for Alaska and the impacts on wildlife are considered in detail. This wildlife includes: black and brown bears, bear-viewing tourism and its management approaches; the impacts on Dall sheep; the effects of winter recreation on ungulates, including mountain caribou; the recreational impacts on bird populations, including bald eagles, black oystercatchers and marbled murrelets; and whale-watching and harbour seal impacts. The effects of recreation caused by camping, hiking trampling pressure on tundra, the invasive plant spread along trails and the development of informal trails in Arctic wildlife refuges are considered. The impacts of off-road vehicles on tundra, helicopter-supported recreation impacts and the effects of waste produced by climbers on Mount McKinley are evaluated. Finally, the effects of recreational fishing and some impacts on native human populations are discussed.
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Based on five years of field studies (1992, 1993, 1994, 1998, 2000), I quantified bi-directional movement of salmon nutrients through an estuary, stream, and old growth forest in a large protected reserve on Haida Gwaii, British Columbia. In 1993, when most data were collected, about 6000 Chum Salmon (Oncorhynchus keta) entered the river of which 22% of the total biomass of senescent carcasses were swept downstream into the estuary and were scavenged by gulls (n = 350) and subtidal invertebrates. Of the 3700 salmon (10 000 kg) transferred by American Black Bear (Ursus americanus) to the riparian zone and partially consumed along the 800 m of stream channel, 5070 kg of salmon tissues abandoned by the bears were scavenged by Northwestern Crows (Corvus caurinus; n = 200) but mostly (4100 kg) by calliphorid blowfly larvae resulting in larval densities averaging 240/m2 throughout the riparian zone. Total nitrogen input to the soils from the combined effects of bear and scavenger activity as well as carcass input was 18 g/m2 within 10 m of the stream channel. δ15N of foliar tissues of Lanky Moss (Rhytidiadelphus loreus), Red Huckleberry (Vaccinium parvifolium), Salal (Gaultheria shallon), and Western Hemlock (Tsuga heterophylla) ranged about 15‰ to 20‰ among adjacent microsites in each species, with higher values occurring in salmon carcass zones. Total nitrogen in foliar tissues ranged from 1% to 2.4% among microsites and was best predicted by positive correlations with foliar 15N values and secondarily by presence/absence of salmon carcasses. This is the first study to integrate estuarine to riparian ecological processes in the cycling of salmonid nutrients and identifies a range of ecological baselines that can inform the multiple restoration programs underway in degraded watersheds in the North Pacific.
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Salmon provide a key source of marine-derived nutrients to aquatic and surrounding terrestrial habitats in coastal areas of the North Pacific. Bears are a major predator of salmon and provide an important pathway for carcass transfer to riparian zones. We studied selective consumption of salmon (Oncorhynchus keta and Oncorhynchus gorbuscha) by bears (Ursus arctos and Ursus americanus) on 12 streams on the central coast of British Columbia, Canada. We predicted that bears would select more energyrich parts, and eat less of each fish (i.e., selective consumption), in streams with more prey and simpler habitat (i.e., streams that facilitate salmon capture). Bears were 12% more likely to consume fish selectively in narrow, shallow streams with less pool volume, where salmon are easier to catch, than in deep, wide streams. However, bears were also 21% more likely to selectively consume fish in streams with more wood obstacles and undercut banks, where hunting was predicted to be more difficult. This suggests that stream characteristics can have significant indirect effects on riparian nutrient subsidies to ecosystems through selective feeding by bears.
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Avoiding predators most often entails a food cost. For the Scandinavian brown bear (Ursus arctos), the hunting season coincides with the period of hyperphagia. Hunting mortality risk is not uniformly distributed throughout the day, but peaks in the early morning hours. As bears must increase mass for winter survival, they should be sensitive to temporal allocation of antipredator responses to periods of highest risk. We expected bears to reduce foraging activity at the expense of food intake in the morning hours when risk was high, but not in the afternoon, when risk was low. We used fine-scale GPS-derived activity patterns during the 2 weeks before and after the onset of the annual bear hunting season. At locations of probable foraging, we assessed abundance and sugar content, of bilberry (Vaccinium myrtillus), the most important autumn food resource for bears in this area. Bears decreased their foraging activity in the morning hours of the hunting season. Likewise, they foraged less efficiently and on poorer quality berries in the morning. Neither of our foraging measures were affected by hunting in the afternoon foraging bout, indicating that bears did not allocate antipredator behavior to times of comparably lower risk. Bears effectively responded to variation in risk on the scale of hours. This entailed a measurable foraging cost. The additive effect of reduced foraging activity, reduced forage intake, and lower quality food may result in poorer body condition upon den entry and may ultimately reduce reproductive success. Electronic supplementary material The online version of this article (doi:10.1007/s00442-016-3729-8) contains supplementary material, which is available to authorized users.
Article
Social play behaviour is a well-described phenomenon, almost ubiquitous among mammals. Despite its prevalence, social play takes several forms and may vary in function across species. For solitary species, the function of play outside of the family group remains unclear. Here, we describe the motor patterns of play among non-littermate wild brown bears Ursus arctos of different age-sex class. Play was documented during a time of abundant food availability in three different scenarios: play among non-littermate subadults, play among non-littermate cubs, and play among a ‘group’ of bears of different age and sex class. We used a previously described behavioural ethogram to recognise play. Play followed typical motor patterns and postures expressed by bears during play-fighting: relaxed face, puckered-lip, ears partially flattened to crescent, wrestling, jaw gaping, play-biting, paw-swatting, and lunging. No vocalisations were conducted during play bouts. Older bears displayed ‘self-handicapping’ and ‘role-reversal’ in the play postures they selected when playing with younger bears, suggesting that tactics vary according to age class and dominance ranking. Playing likely allows for the evaluation of conspecifics in a non-aggressive way during times of reduced competition and could also relieve stress in complex social situations.
Article
Weexamined the relationship between environmental factors of a spawning habitat and body shape at maturity in 16 pink salmon (Oncorhynchus gorbuscha) populations. The divergence vector (indicator of body depth and head size development) in both sexes was significantly correlated with distance from the sea and was described by a hump-shaped relationship. An exaggerated body shape was most developed at mid-distance from the sea and less developed both near and far from the sea. The observed frequency of bears decreased significantly with distance from the sea, implying that bear predation on salmon is most intense near the sea. Therefore, our results imply that shape-selective predation by bears affects the shape of pink salmon in rivers where the spawning habitat is near the sea and that migration costs inhibit development of an exaggerated body depth and head size in salmon in rivers where the spawning habitat is far from the sea. © 2016, National Research Council of Canada. All Rights Reserved.
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We examined temporal and spatial activity of grizzly bears (Ursus arctos) and black bears (Ursus americamis) in 3 areas of coastal British Columbia to investigate (1) variation within and between the 2 species, and (2) the influence of human activity on bear activity. Bear detections at remote camera sites were used to measure activity. The Nimpkish Valley had black bears only, and high human use divided into periods with and without hunting. Black bears were active primarily during the day, whether there was hunting or not. In the Khutzeymateen Valley, grizzly bears were active primarily during the day, and black bears were nocturnal; there was no human use. Black bears likely avoided some areas because of the presence of grizzly bears. The Tweedsmuir study area had black bears and grizzly bears in areas of both low and high human use. Grizzly bears were detected more frequently than black bears in low and high human use areas. During periods when bears were fishing for salmon (Oncorhynchus spp.), lone adult grizzly bears and grizzly bear family groups were both detected less frequently and were more active during the night in the area of high human use than in the area of low human use. Subadult grizzly bears were detected more frequently in the area of high human use than in the area of low human use, and they tended to be more active during the day. Coastal grizzly bears were generally diumal in areas of low human use. In areas of high human use, grizzly bears had different temporal and spatial activity patterns, and the magnitude and direction of these differences varied between age and sex classes. Black bears seemed to alter their temporal patterns of activity more in response to grizzly bear activity than to human activity.
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Brown bear (Ursus arctos) activity along salmon (Oncorhynchus spp.) streams has frequently been characterized as crepuscular. Suggested explanations include: responses to daily changes in salmon abundance, responses to daily cycles of light and temperature, natural feeding schedules, and avoidance of people. We investigated the last hypothesis by comparing bear activity at 2 adjacent streams in Katmai National Park, both spawning habitat for the same run of sockeye salmon (Oncorhynchus nerka) but differing in their levels of human use. During 1989 and 1991, bear activity at Margot Creek, where no human activity was observed, was distributed uniformly throughout the day (based on 240 observation hours; P > 0.90 both years). This uniform distribution contrasted with the crepuscular pattern of bear activity observed at Brooks River, where human use came from a 60-person lodge, a 60-person campground (20 sites), and substantial day-use. Significant differences (P < 0.001) in activity by time of day were found at Brooks River during the autumn salmon spawning period (sampled 1988-92,905 observation hr). The midday depression in activity was greatest for bears less tolerant of people (>68% of the adult bears seen). As human activity increased over the years of the study, these shier bears shifted their stream use among time periods: midday activity decreased while activity during the 2000-2200 hour time block increased significantly (P < 0.050). Our results indicated that avoidance of people cannot be discounted as a factor contributing to observed crepuscular patterns of use in brown bears.
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Activity patterns of 15 female black bears (Ursus americanus) were studied using motion-sensitive radiotransmitters during late summer and autumn of 1990 and 1991 in La Mauricie National Park, Québec. Female black bears primarily were diurnal during this period, and no difference in activity patterns was detected between solitary females and females with young. Onset of activity followed sunrise by an average of 30 min, and cessation occurred on average 141 min after sunset. Activity and resting periods averaged 245 and 57 min, respectively. The proportion of active bears was highest during the ripening time of berries (Rubus idaeus, Vaccinium myrtilloides, and Prunus virginiand) in late August and of beechnuts (Fagus grandifolid) in early October. Bears denned earlier in 1991 than in 1990, probably because of the poor beechnut crop.
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Onset of feeding by mountain lions (Puma concolor) on individual prey was studied with an automatic camera near mule deer (Odocoileus hemionus) that had been killed and cached by mountain lions. We categorized mountain lions as adult males, adult females, females with juveniles, and females with kittens. After sunset, females with kittens returned to kills significantly earlier than males, females, or females with juveniles. Early feeding by females with kittens might reflect avoidance of conspecifics, which are known to kill kittens. Alternatively, mothers with young kittens may remain closer to caches of prey than lone males, females, or mothers with juveniles. Increased energetic needs of lactating mothers also may dictate earlier feeding.
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The first capture of a European brown bear (Ursus arctos) in Spain occurred in the National Hunting Reserve of Riaño on 16 October 1985. An adult male was radio-marked and movements and activities were monitored until September 1988. Distances between daily radio-locations ranged from <0.1 km to 20.5 km and averaged 1.6 km. The 2 extremes were attributed to food availability, particularly winter-starved ungulates, and breeding. Seasonal home ranges varied from 39 km2 (fall/winter) to 1,272 km2 (breeding). Movements during 1987 and 1988 totaled 246 and 1,308 km2, respectively. Seasonal activity data from diel recordings (n = 92) indicated that the bear's activity was greatest during breeding period (43%). Diel activity patterns were crepuscular year-round. Daytime activity was lowest during post-denning and highest in fall/winter, averaging over 50% active. Food availability, breeding season, and levels of human activity were felt to be the most important factors influencing this bear's movements and activity patterns in the Cantabrian Mountains of Spain.
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Mayfly larvae of Paraleptophlebia heteronea (McDunnough) had two antipredator responses to a nocturnal fish predator (Rhinichthys cataractae (Valenciennes)): flight into the drift and retreat into interstitial crevices. Drift rates of Paraleptophlebia abruptly increased by 30 fold when fish were actively foraging in the laboratory streams but, even before fish were removed, drift began returning to control levels because larvae settled to the substrate and moved to areas of low risk beneath stones. This drifting response was used as an immediate escape behavior which likely decreases risk of capture from predators which forage actively at night. Surprisingly, drift most often occurred before contact between predator and prey, and we suggest that in darkness this mayfly may use hydrodynamic pressure waves for predator detection, rather than chemical cues, since fish forage in an upstream direction. Although drifting may represent a cost to mayfly larvae in terms of relocation to a new foraging area with unknown food resources, the immediate mortality risk probably out-weighs the importance of staying within a profitable food patch because larvae can survive starvation for at least 2 d. In addition to drifting, mayflies retreated from upper, exposed substrate surfaces to concealed interstitial crevices immediately after a predator encounter, or subsequent to resettlement on the substrate after predator-induced drift. A latency period was associated with this response and mayflies remained in these concealed locations for at least 3 h after dace foraging ceased. Because this mayfly feeds at night and food levels are significantly lower in field refugia under stones, relative to exposed stone surfaces, predator avoidance activity may limit foraging time and, ultimately, reduce the food intake of this stream mayfly.
Article
Black Bears (Ursus americanus) are usually active during daylight but are known to shift to crepuscular and nocturnal activity when daylight activities are disrupted. The principle factors currently thought to promote this shift are the presence of Brown Bears (U. arctos) and humans. I examined the extent of diurnal, crepuscular and nocturnal activity of Black Bears in an estuary and stream during salmon spawning migration at Bag Harbour, Haida Gwaii, off coastal British Columbia. A predominance of daylight activity was predicted as there are no Brown Bears on Haida Gwaii and only minimal human disturbance in the remote area. Results show that during daylight, there was low but consistent foraging activity in the stream but no daylight foraging on the estuary even when salmon were abundant. Bears were intolerant of each other during daylight and would rarely forage within visual range of each other. Use of night-viewing goggles show that most foraging on the stream and all foraging on the estuary occurred during darkness with peak activity four to six hours after sunset. Up to six bears foraged simultaneously in the shallows in close proximity to each other with few agonistic interactions. High foraging success during darkness occurred because salmon showed reduced evasive responses to shoreline disturbance compared with daylight. These observations suggest that occasional nocturnal activity by Black Bears on the mainland of western North America might be the result of preferred foraging periods rather than disturbance with diurnally active competitors.
Article
Well-used and possibly ancient bear trails occur in different regions of the home range of bears (Ursus) and are suspected of functioning in intraspecific communication. I monitored Black Bears (U. americanus) in a riparian habitat of an old growth forest on the Queen Charlotte Islands during daylight and also during darkness with the use of light-enhancing night-viewing goggles. During daylight, bears regularly moved off the trails on first visual detection of my presence (>20 m). However, during darkness, bears maintained high fidelity to these trails even during my close approaches (1 m), suggesting these trails act as nocturnal sensory corridors.
Article
Effects of predation by brown bears (Ursus arctos) on sockeye salmon (Oncorhynchus nerka) were studied at Grassy Point Creek, a tributary of Karluk Lake on Kodiak Island, Alaska, during the summers of 1964 and 1965. In 1964 bears were allowed free access to the stream, but in 1965 an attempt was made to exclude them with an electric fence. Bears were efficient predators in the stream, killing up to 79 percent of the salmon in 1964; however, only 9.6 percent of the dead females sampled were unspawned bear-killed fish. The maximum estimate of eggs lost to bear predation in 1964 was about 1 million, compared with a total loss, from all causes, of 8 million potential eggs. As a result of certain behavioral patterns of sockeye salmon, bears usually take spawned-out rather than unspawned females. The ratio of males to females in each year's escapement approached 1:1; the ratio among bear kills was about 3:2. Males acted as a buffer against predation on females. The fence reduced bear predation by two-thirds. It is concluded that bear predation has little adverse effect on the production of sockeye salmon.
Article
A total of 1015 registered incidents of damage to domestic animals and bee hives caused by brown bears during the years 1984 to 1988 were evaluated by the National Insurance Institute. The investigation covered the entire area populated by brown bears in Bulgaria. An attempt is made to analyse the annual, seasonal, and circadian rhythms of the attacks, the victims, and the characteristics of the attacks. During the investigation period, a total of 1897 domestic animals were killed and 637 bee hives destroyed by the bears. Insurance premiums were paid for these losses. The evaluation shows a sharp increase in the number of attacks during 1985 and 1986 — 51% of all attacks and 51.7% of all killed animals and destroyed bee hives. This fact is correlated to less strict control procedures on the part of the hunting authorities. Within the course of a year most of the attacks occur during the summer months and in early autumn. The maximum is in August with 27.4% of attacks and 39.2% of victims. A separate registration of attacks on bee hives shows two maxima, one in May and the other in July. The displacement of this predacious behaviour toward the summer months in comparison to the time period 1975–1983 can be explained by the dryness of the past years, which had a negative impact on the growth of vegetation, the main source of food for the bears. The circadian distribution of the attacks show a preference for the time between 10:00 PM and 4:00 AM — 50.9% of attacks occur then. Sometimes poor weather conditions are used to strike upon the victims unseen. Among domestic animals attacks on sheep are most frequent, accounting for an average of 87.4% of incidents and 92.6% of victims. The behaviour of the bears during the attacks is variable and depends upon the bear's physical condition, his aggressiveness, and his individual experience. The particular composition of the bear's nutrition would permit feeding of the bears during the unfavourable seasons, thus considerably reducing the damage inflicted. Single individuals that still attack domestic animals despite sufficient food should be shot.
Article
Nocturnal foraging was examined in American White Pelicans (Pelecanus erythrorhynchos) at the Dauphin River, about 50 km from a breeding colony on Lake Winnipeg, Manitoba, Canada. From two to three times as many pelicans foraged at night as in the daytime, with foraging flocks being larger at night. In contrast, more pelicans were present at adjacent loafing sites during the day. Capture rates were highest for flocks of up to 100 foragers in the daytime, but showed no relationship to flock size at night. Rates of bill dipping and mean duration of dips were significantly greater at night, but capture rates were significantly lower. Lower capture rates at night were to some extent offset by the capture of more large fish, probably because they were more accessible at that time. Most of the day-night differences in capture efficiency appeared to be due to lower visual sensitivity of pelicans at night.
Article
Direct observations on the foraging activities of lions, based on 920 attempts to capture prey and 156 kills, on the plains of Etosha National Park, Namibia, revealed a regular nocturnal pattern of mostly coordinated group hunting. Lions scavenged rarely and killed mainly prey animals weighing less than 50 kg, which contributed to 73% of the observed kills and 50% of the estimated biomass consumed. Capture success increased with lion group size and was also greater during coordinated group hunts. Lions hunted most of the prey that they encountered, showing a preference for large prey species. Average food acquisition ranged from 8.7 kg/day per lioness in the dry season to 14 kg/day per lioness in the wet season. During the dry season, coordinated cooperative hunting was essential and lionesses most often formed groups of 2, thereby acquiring higher daily food intake than groups of other sizes. In the wet season, lioness groups of all sizes obtained more than the estimated daily requirements, and lionesses did not uniformly forage in the smaller groups capable of greater food acquisition.
Article
Habitat use and behavior of grizzly bears (Ursus arctos) were studied in 3 areas of the Arctic National Wildlife Refuge, northeast Alaska, during 1982 and 1983. Scanning for bears resulted in 386 and 388 h of behavioral and habitat use information. Vegetation on 3,626 ha in the Caribou Pass- Kongakut River study area was mapped to Viereck-Dymess (1980) level IV. Grizzly bears devoted most of their nonhibernating time to feeding and foraging. Food habits and habitat use were influenced by the phenological development of herbaceous plants and berry-producing plants and availability of animal food items.
Article
ZusammenfassungDas Verhalten des Baribal (Ursus americanus) wurde im Sommer 1967 in Alaska an einem Fluß beobachtet, in dem Ketalachs und Buckellachs ablaichen. Die Bären waren von der Morgendämmerung an 2 Std. aktiv und mehrere Stunden vor und nach Sonnenuntergang. In erster Linie fraßen sie Lachse, die andere Bären getötet und liegen gelassen hatten. Auf einen gefangenen Lachs kamen etwa 7 Versuche. Baribals bevorzugen den Rogen und lassen oft den Rest liegen; sie erkennen laichreife ♀♀. Obwohl sie gleich viele ♂♂ wie ♀♀ fingen, behielten sie doppelt so viele ♀♀; 65 % davon hatten beim Fang noch nicht abgelaicht. Insgesamt fangen die Bären 8 % der weiblichen Lachse, ehe sie ablaichen können. Fisch-Reviere scheinen die Bären nicht zu haben.
Article
Consumption choice by brown (Ursus arctos) and black bears (U. americanus) feeding on salmon was recorded for over 20,000 bear-killed fish from 1994 to 1999 in Bristol Bay (sockeye salmon, Oncorhynchus nerka) and southeastern Alaska (pink, O. gorbuscha and chum salmon O. keta). These data revealed striking patterns of partial and selective consumption that varied with relative availability and attributes of the fish. As the availability of salmon decreased, bears consumed a larger proportion of each fish among both years and habitats. When availability was high (absolute number and density of salmon), bears consumed less biomass per captured fish, targeting energy-rich fish (those that had not spawned) or energy-rich body parts (eggs in females; brain in males). In contrast, individual fish were consumed to a much greater extent, regardless of sex or spawning status, in habitats or years of low salmon availability. The proportion of biomass consumed per fish was similar for males and females, when spawning status was statistically controlled, but bears targeted different body parts: the body flesh, brain and dorsal hump in males and the roe in females. Bears thus appeared to maximize energy intake by modifying the amount and body parts consumed, based on availability and attributes of spawning salmon.
Article
Typescript. Thesis (Ph. D.)--University of Florida, 1996. Vita. Includes bibliographical references (leaves 343-372).
Further studies of predator and scavenger use of chum salmon in stream and estuarine habitats at Bag Harbour, Gwaii Haanas
  • T E Reimchen
Reimchen, T.E. 1994. Further studies of predator and scavenger use of chum salmon in stream and estuarine habitats at Bag Harbour, Gwaii Haanas. Tech. Rep., Canadian Parks Service, Queen Charlotte City, B.C.
The Serengeti lion Foraging dynamics of lions in a semi-arid envi-ronment
  • G B Schaller
Schaller, G.B. 1972. The Serengeti lion. University of Chicago Press, Chicago. Stander, P.E. 1992. Foraging dynamics of lions in a semi-arid envi-ronment. Can. J. Zool. 70: 8–21.
Energy, diet selection and restoration of brown bear populations. In Density-dependent population regulation of black, brown, and polar bears
  • B K Gilbert
  • R M Lanner
Gilbert, B.K., and Lanner, R.M. 1995. Energy, diet selection and restoration of brown bear populations. In Density-dependent population regulation of black, brown, and polar bears. Edited by M. Taylor. Proceedings of the Ninth International Conference on Bear Research and Management, Missoula, Mont., 23-28 February 1994. International Association for Bear Research and Management, Washington, D.C. Monogr. Ser. No. 3. pp. 231-240.
Diel activity of a remnant population of Euro-pean brown bears International Association for Bear Re-search and Management
  • H U Roth
Roth, H.U. 1983. Diel activity of a remnant population of Euro-pean brown bears. In Bears—Their Biology and Management: Proceedings of the Fifth International Conference on Bear Re-search and Management, Madison, Wis., 10–13 February 1980. Edited by E.C. Meslow. International Association for Bear Re-search and Management, Madison, Wis. pp. 223–229. [Available from Clifford J. Martinka, Supervisory Research Biologist, Gla-cier National Park, West Glacier, MT 59936, U.S.A.]
Movement and activity patterns of a European brown bear in the Cantabrian Mountains, Spain International Association for Bear Research and Management
  • A P Clevenger
  • F J Purroy
  • M R Pelton
  • Management
  • B C Victoria
Clevenger, A.P., Purroy, F.J., and Pelton, M.R. 1990. Movement and activity patterns of a European brown bear in the Cantabrian Mountains, Spain. In Bears—Their Biology and Management: Proceedings of the Eighth International Conference on Bear Research and Management, Victoria, B.C., 20–25 February 1989. Edited by L.M. Darling and W.R. Archibald. International Association for Bear Research and Management, Washington, D.C. pp. 205–211. [Available from Michael R. Pelton, Department of Forestry, Wildlife, and Fisheries, The University of Tennessee, P.O. Box 1071, Knoxville, TN 37901-1071, U.S.A.]
Folk. International Union for the Conservation of Nature and Natural Resources
  • M H Luque
  • A W Stokes
Luque, M.H., and Stokes, A.W. 1976. Fishing behaviour of Alaskan brown bear. In Bears-Their Biology and Management: Proceedings of the Third International Conference on Bear Research and Management, Binghamton, N.Y., 31 May -1 June 1974, and Moscow, U.S.S.R., 11 June 1974. Edited by M.R. Pelton, J.W. Lentfer, and G.E. Folk. International Union for the Conservation of Nature and Natural Resources, Morges, Switzerland. pp. 71-78.
Department of Forestry, Wildlife, and Fisheries
  • Michael R Pelton
Michael R. Pelton, Department of Forestry, Wildlife, and Fisheries, The University of Tennessee, P.O. Box 1071, Knoxville, TN 37901-1071, U.S.A.]
International Association for Bear Research and Management, Madison, Wis
  • H U Roth
  • Madison Management
Roth, H.U. 1983. Diel activity of a remnant population of European brown bears. In Bears-Their Biology and Management: Proceedings of the Fifth International Conference on Bear Research and Management, Madison, Wis., 10-13 February 1980. Edited by E.C. Meslow. International Association for Bear Research and Management, Madison, Wis. pp. 223-229. [Available from Clifford J. Martinka, Supervisory Research Biologist, Glacier National Park, West Glacier, MT 59936, U.S.A.]
International Union for the Conservation of Nature and Natural Resources
  • D Stonorov
  • A Stokes
Stonorov, D., and Stokes, A. 1972. Social behaviour of the Alaska brown bear. In Bears-Their Biology and Management: Proceedings of the Second International Conference on Bear Research and Management, Calgary, Alta., 6-9 November 1970. Edited by S. Herrero. International Union for the Conservation of Nature and Natural Resources, Morges, Switzerland. pp. 232-242.