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Effect of diet on mass loss of bobcat scat after exposure to field conditions
Abstract
Many studies have related estimates of predator diet to prey detectability in scats, but no studies have examined effects of diet on deterioration of scat in the field and the ability to recognize the species depositing the scat. Scats from captive bobcats (Lynx rufus) fed 1 of 3 diets—(mice [Mus musculus] and rats [Rattus norvegicus], rabbit [Oryctolagus cuniculus], and deer [Odocoileus virginianus])—were used to determine the effect of prey species on the integrity of an exposed scat. Diet affected (P < 0.001) mass loss of scats. Mass loss of scats containing mice and rats was similar (P>0.05) to mass loss of scats containing rabbit, but mass loss of scats containing deer was greater (P < 0.05) than scat containing mice and rats or rabbit. If mass loss of scat reduces the ability of biologists to identify the species depositing the scat, those scats that lose mass at a faster rate would become unidentifiable sooner. These scats would then not be collected or would not be included in predator-specific diet analyses, which could bias the results (e.g., underrepresent the importance of deer in bobcat diet). We suggest that diet-specific mass loss of scats may occur in other species and that research is needed to evaluate this possibility. Studies also are needed to determine adequate sampling intervals to eliminate effects of mass loss bias.
... We attempted to collect recently deposited faeces (i.e. faeces that had not been bleached white by the sun and had not begun to deteriorate:Godbois et al. 2005), but ultimately we could not determine how long faeces had been in the environment before collection. Upon collection, faeces were frozen until they were used for placement in this study. ...
... Taken as a whole, these findings suggest that the utility of roads for faeces deposition surveys is both species and site specific. Second, faeces deterioration rates (i.e. the amount of time a faeces remains detectable in the environment:Godbois et al. 2005) may influence detection probabilities. For our faeces detection study, bias from deterioration rates seemed minimal because of the short and constant temporal window (e.g. ...
... season), biological (e.g. diet:Godbois et al. 2005) and anthropogenic (e.g. road traffic volume) factors. ...
Determining reliable estimates of carnivore population size and distributions are paramount for developing
informed conservation and management plans. Traditionally, invasive sampling has been employed to monitor carnivores, but non-invasive sampling has the advantage of not needing to capture the animal and is generally less expensive. Faeces sampling is a common non-invasive sampling technique and future use is forecasted to increase due to the low costs and logistical ease of sampling, and more advanced techniques in landscape and conservation genetics. For many species, faeces sampling often occurs on or alongside roads. Despite the commonality of road-based faeces sampling, detectability issues are often not addressed. We sought to test whether faeces detection probabilities varied by species – coyote (Canis latrans) versus kit
fox (Vulpes macrotis) – and to test whether road characteristics influenced faeces detection probabilities. We placed coyote and kit fox faeces along roads, quantified road characteristics, and then subsequently
conducted ‘blind’ road-based faeces detection surveys in Utah during 2012 and 2013. Technicians that surveyed the faeces deposition transects had no knowledge of the locations of the placed faeces. Faeces detection probabilities for kit foxes and coyotes were 45% and 74%, respectively; larger faeces originated from coyotes and were more readily detected. Misidentification of placed faeces was rare and did not differ by species. The width of survey roads and the composition of a road’s surface influenced detection probabilities. We identified factors that can influence faeces detection probabilities. Not accounting for variable detection
probabilities of different species or not accounting for or reducing road-based variables influencing faeces detection probabilities could hamper reliable counts of mammalian faeces, and could potentially reduce precision of population estimates derived from road-based faeces deposition surveys. We recommend that wildlife researchers acknowledge and account for imperfect faeces detection probabilities during faecal sampling. Steps can be taken during study design to improve detection probabilities, and during the analysis phase to account for variable detection probabilities.
... For other species, a non-trail-based survey would necessitate alternative and more expensive survey protocols such as the use of scatsniffing dogs (Smith et al. 2003). The value of trail-based surveys for canid scats also would have to be reevaluated if loss of scats (e.g., through effects of weather or traffic) from transects occurred at rates high enough to bias results (Sanchez et al. 2004, Godbois et al. 2005, Livingston et al. 2005. ...
Carnivores are difficult to survey due, in large part, to their relative rarity across the landscape and wariness toward humans. Several noninvasive methods may aid in overcoming these difficulties, but there has been little discussion of the relative merits and biases of these techniques. We assess the value of 5 noninvasive techniques based on results from 2 multiyear studies of carnivores (including members of Carnivora and Didelphidae) in New York forests. Two metrics were particularly valuable in assessing the species‐specific value of any particular survey technique: latency to initial detection (LTD) and probability of detection (POD). We found differences in the value of techniques in detecting different species. For midsized species (raccoon [Procyon lotor], fisher [Martes pennanti], opossum [Didelphis virginiana], and domestic cat [Felis catus]), camera traps and track‐plates were approximately equivalent in detection efficiency, but the potential for wariness toward the survey apparatus resulted in higher LTD for track‐plates than for cameras. On the other hand, track‐plates detected small carnivores (marten [M. americana] and weasels [Mustela spp.]) more often than cameras and had higher PODs for small and midsized species than did cameras. Cameras were efficient mechanisms for surveying bears (Ursus americanus; low LTD, high POD) but functioned poorly for discerning presence of coyotes (Canis latrans; high LTD, low POD). Scat surveys and snowtracking were the best methods for coyotes, which avoided camera traps and artificial tracking surfaces. Our analysis of fecal DNA revealed that trail‐based fecal surveys were inefficient at detecting species other than coyotes, with the possible exception of red foxes (Vulpes vulpes). Genetic analyses of feces and snowtracking revealed the presence of foxes at sites where other techniques failed to discern these species, suggesting that cameras and track‐plates are inefficient for surveying small canids in this region. The LTD of coyotes by camera traps was not correlated with their abundance as indexed by scat counts, but for other species this metric may offer an opportunity to assess relative abundance across sites. Snowtracking surveys were particularly robust (high POD) for detecting species active in winter and may be more effective than both cameras and track‐plates where conditions are suitable. We recommend that survey efforts targeting multiple members of the carnivore community use multiple independent techniques and incorporate mechanisms to truth their relative value.
... For other species, a non-trail-based survey would necessitate alternative and more expensive survey protocols such as the use of scatsniffing dogs (Smith et al. 2003). The value of trail-based surveys for canid scats also would have to be reevaluated if loss of scats (e.g., through effects of weather or traffic) from transects occurred at rates high enough to bias results (Sanchez et al. 2004, Godbois et al. 2005, Livingston et al. 2005. ...
Carnivores are difficult to survey due, in large part, to their relative rarity across the landscape and wariness toward humans. Several noninvasive methods may aid in overcoming these difficulties, but there has been little discussion of the relative merits and biases of these techniques. We assess the value of 5 noninvasive techniques based on results from 2 multiyear studies of carnivores (including members of Carnivora and Didelphidae) in New York forests. Two metrics were particularly valuable in assessing the species-specific value of any particular survey technique: latency to initial detection (LTD) and probability of detection (POD). We found differences in the value of techniques in detecting different species. For midsized species (raccoon [Procyon lotor], fisher [Martes pennanti], opossum [Didelphis virginiana], and domestic cat [Felis catus]), camera traps and track-plates were approximately equivalent in detection efficiency, but the potential for wariness toward the survey apparatus resulted in higher LTD for track-plates than for cameras. On the other hand, track-plates detected small carnivores (marten [M. americana] and weasels [Mustela spp.]) more often than cameras and had higher PODs for small and midsized species than did cameras. Cameras were efficient mechanisms for surveying bears (Ursus americanus; low LTD, high POD) but functioned poorly for discerning presence of coyotes (Canis latrans; high LTD, low POD). Scat surveys and snowtracking were the best methods for coyotes, which avoided camera traps and artificial tracking surfaces. Our analysis of fecal DNA revealed that trail-based fecal surveys were inefficient at detecting species other than coyotes, with the possible exception of red foxes (Vulpes vulpes). Genetic analyses of feces and snowtracking revealed the presence of foxes at sites where other techniques failed to discern these species, suggesting that cameras and track-plates are inefficient for surveying small canids in this region. The LTD of coyotes by camera traps was not correlated with their abundance as indexed by scat counts, but for other species this metric may offer an opportunity to assess relative abundance across sites. Snowtracking surveys were particularly robust (high POD) for detecting species active in winter and may be more effective than both cameras and track-plates where conditions are suitable. We recommend that survey efforts targeting multiple members of the carnivore community use multiple independent techniques and incorporate mechanisms to truth their relative value.
... the scat [30]. Previous research on wolf scats shows that scat DNA degrades more rapidly in samples that are in direct contact with soil, likely because they are kept wet, which may facilitate their invasion by decomposers (e.g., bacteria, fungi, insects) [31]. ...
Scat is frequently used to study animal diets because it is easy to find and collect, but one concern is that gross fecal analysis (GFA) techniques exaggerate the importance of small-bodied prey to mammalian mesopredator diets. To capitalize on the benefits of scat, we suggest the analysis of scat carbon and nitrogen isotope values (δ¹³C and δ¹⁵N). This technique offers researchers a non-invasive method to gather short-term dietary information. We conducted three interrelated studies to validate the use of isotopic values from coyote scat: 1) we determined tissue-to-tissue apparent C and N isotope enrichment factors (ε¹³* and ε¹⁵*) for coyotes from road kill animals (n = 4); 2) we derived diet-to-scat isotope discrimination factors for coyotes; and 3) we used field collected coyote scats (n = 12) to compare estimates of coyote dietary proportions from stable isotope mixing models with estimates from two GFA techniques. Scat consistently had the lowest δ¹³C and δ¹⁵N values among the tissues sampled. We derived a diet-to-scat Δ¹³C value of -1.5‰ ± 1.6‰ and Δ¹⁵N value of 2.3‰ ± 1.3‰ for coyotes. Coyote scat δ¹³C and δ¹⁵N values adjusted for discrimination consistently plot within the isotopic mixing space created by known dietary items. In comparison with GFA results, we found that mixing model estimates of coyote dietary proportions de-emphasize the importance of small-bodied prey. Coyote scat δ¹³C and δ¹⁵N values therefore offer a relatively quick and non-invasive way to gain accurate dietary information.
... Seasonal variation in scat persistence was a pertinent issue in my study because my study spanned seasons. Another factor that may vary by season is diet, and the content of scats influences their decay rates (Godbois, Conner, Leopold, & Warren, 2005). As such, infrequent surveys may be less effective at detecting certain kinds of scats or the scats of certain species. ...
Human-coyote conflict has intensified in Nova Scotia, following a fatal attack in Cape Breton Highlands National Park of Canada (CBHNPC) in October, 2009. This conflict has impacted people and coyotes across the province, and raised numerous questions about how humans and coyotes relate to one another and what steps we might take to avert future conflict. From 2011-2012, I used scat, remote camera, and snow tracking surveys to assess the degree of spatial overlap between human and coyote activity in CBHNPC. I found a negative correlation between hiker/biker and coyote activity in the summer and fall [r=-.830, n=14, p<.01]. In the winter, I found no correlation between human and coyote activity [r=.006, n=10], and a negative correlation between coyote and domestic dog activity [r=-.612, n=10, p<.05]. I discuss the implications of these research findings and the application of noninvasive survey methods in this, and potentially other, human-wildlife conflicts.
... Also, the dietary content of the scat itself affects the scat's physical resistance against disintegration. Scats produced by bobcats, for example, have shown a different rate of degradation depending on the choice of prey (Godbois et al., 2005). Different body parts from the same prey will in a similar manner inflect on the stability of the scat. ...
Fossilized soft tissues of animals (e.g. muscles, hair and feathers) are valuable sources of palaeobiological information, but a poor preservation potential makes them undesirably scarce in the fossil record. The aim of this review is to summarize main findings, current progress and the analytical constraints of detecting fossilized soft tissues in coprolites from, mainly, freshwater and terrestrial carnivorous vertebrates. We conclude that soft-tissue inclusions in coprolites are sources of two important lines of information: the fossils can be put in a direct palaeoecological context, and; characters of extinct taxa are more likely preserved in the phosphate-rich taphonomic microenvironment of coprolites than elsewhere. As a result, it is possible to unravel the deep-time origins of host-parasite relations, to understand ancient trophic food webs and detect new soft-tissue characters of different animal groups. Examples of the latter include muscle tissues from a tyrannosaurid prey, tapeworm eggs (including a developing embryo) in a Permian shark coprolite, as well as hair from multituberculates and, probably, from stem-mammals (Therapsids). Additionally, the use of coprolites in an archaeological context is briefly reviewed with focus on key aspects that may become implemented in studies of pre-Quaternary specimens as well. In sum, there is a wide range of information that can be extracted from coprolites, which has not yet been fully explored in palaeontological studies.
... Most scats collected were as complete and fresh as possible, but partial ones also were collected and analyzed. Occasionally, we collected scats during the capture of bobcats, providing fresh samples that facilitated the differentiation of scats from those of other species, such as coyotes (Canis latrans; Godbois et al., 2005). ...
We studied the diet and foraging behavior of bobcats (Lynx rufus) in the Chihuahuan desert, Mexico, from 2005-2007 to test if bobcats will select energetically profitable prey regardless of their relative abundance. We estimated frequency of occurrence and percentage of occurrence for species of prey in the diet through analysis of scats (n=117) and evaluated selection of prey by cpmparing availability against consumption, based on biomass and number of prey consumed as represented in scats. Bobcats consumed a wide variety of prey, but rodents and lagomorphs dominated the diet. Species of prey were not consumed according to availability; combined lagomorphs had the highest probability of being selected based on densities and biomass despite their lower availability. Whithin lagomorphs, based on their availability, rabbits (Sylvilagus audubonii) were selected more often than jackrabbits. By analyzing the availability and biomass of prey against its consumption, we determined that bobcats do not select prey for high availability but act as specialist foragers. Foraging theory provides the best explanation of dietary selection by bobcats in our study area.
... For other species, a non-trail-based survey would necessitate alternative and more expensive survey protocols such as the use of scatsniffing dogs (Smith et al. 2003). The value of trail-based surveys for canid scats also would have to be reevaluated if loss of scats (e.g., through effects of weather or traffic) from transects occurred at rates high enough to bias results (Sanchez et al. 2004, Godbois et al. 2005, Livingston et al. 2005. ...
Carnivores are difficult to survey due, in large part, to their relative rarity across the landscape and wariness toward humans. Several noninvasive methods may aid in overcoming these difficulties, but there has been little discussion of the relative merits and biases of these techniques. We assess the value of 5 noninvasive techniques based on results from 2 multiyear studies of carnivores (including members of Carnivora and Didelphidae) in New York forests. Two metrics were particularly valuable in assessing the species-specific value of any particular survey technique: latency to initial detection (LTD) and probability of detection (POD). We found differences in the value of techniques in detecting different species. For midsized species (raccoon [Procyon lotor], fisher [Martes pennanti], opossum [Didelphis virginiana], and domestic cat [Felis catus]), camera traps and track-plates were approximately equivalent in detection efficiency, but the potential for wariness toward the survey apparatus resulted in higher LTD for track-plates than for cameras. On the other hand, track-plates detected small carnivores (marten [M. americana] and weasels [Mustela spp.]) more often than cameras and had higher PODs for small and midsized species than did cameras. Cameras were efficient mechanisms for surveying bears (Ursus americanus; low LTD, high POD) but functioned poorly for discerning presence of coyotes (Canis latrans; high LTD, low POD). Scat surveys and snowtracking were the best methods for coyotes, which avoided camera traps and artificial tracking surfaces. Our analysis of fecal DNA revealed that trail-based fecal surveys were inefficient at detecting species other than coyotes, with the possible exception of red foxes (Vulpes vulpes). Genetic analyses of feces and snowtracking revealed the presence of foxes at sites where other techniques failed to discern these species, suggesting that cameras and track-plates are inefficient for surveying small canids in this region. The LTD of coyotes by camera traps was not correlated with their abundance as indexed by scat counts, but for other species this metric may offer an opportunity to assess relative abundance across sites. Snowtracking surveys were particularly robust (high POD) for detecting species active in winter and may be more effective than both cameras and track-plates where conditions are suitable. We recommend that survey efforts targeting multiple members of the carnivore community use multiple independent techniques and incorporate mechanisms to truth their relative value.
... Balharry, 1993), but scats rapidly lose their scent after a few days, meaning that studies are often restricted to a subset of the freshest scats that still have scent (Birks et al., 2004). Additionally, diet composition can alter mass loss of scats, affecting scat origin identification (Godbois et al., 2005). Differential rigor about when a scat qualifies for inclusion in analysis among studies may therefore preclude objective comparisons of results (Birks et al., 2004). ...
Knowledge of a carnivore's foraging behaviour is central to understanding its ecology. Scat-content analysis provides a non-invasive way to collect such information but its validity depends on attributing scats to the correct species, which can prove problematic where similarly sized species occur sympatrically. Here we provide the first description of the diet of European pine marten Martes martes in Scotland based on genetically identified scats (n = 2449). Concurrent small mammal live trapping also allowed us to determine preferential selection of small mammal species. We found the marten diet was almost entirely formed by three principal foods: Microtus agrestis (39%), berries (Sorbus aucuparia and Vaccinium myrtillus: 30%) and small birds (24%). The seasonal dominance of these foods in the diet suggested a facultative foraging strategy, with a short period in which the diet was more generalized. A discrepancy in the occurrence of Microtus in the diet (77% of small mammals consumed) and marten home ranges (12% of small mammals trapped) indicated a frequency-independent preference for this prey, one which differentiated British marten from marten in continental Europe. Microtus were the marten's staple prey and taken with relative consistency throughout the year, even at times when rodent populations were at their least abundant. Martens supplemented their diet with small birds and fruits as these foods became abundant in summer. The diet became generalized at this time, reflected by a threefold increase in diet niche breadth. Microtus consumption was significantly reduced in autumn, however, when their populations peak in abundance. The autumn diet was instead dominated by fruit; an abrupt dietary switch suggesting a frequency-dependent preference for fruit irrespective of the abundance of alternative prey.
... Food habits of carnivores can be assessed by various methods (see Mills, 1984Mills, , 1992, however, each method is subject to biases (Klare et al., 2011). Direct observations of kills can often be difficult in certain habitats and using scat analysis (Godbois et al., 2005), based on indentifying undigested prey remains in scat, may be preferred for species that are not easily observed. This method has previously been applied for the cheetah (Marker et al., 2003;Wachter et al., 2006) as well as many other felids, such as leopard (Panthera pardus) (Henschel et al., 2005;Johnson et al., 1993), cougar (Felis concolor) (Ackerman et al., 1984), and Pallas's cats (Otocolobus manul) (Ross et al., 2010). ...
Feeding ecology of the critically endangered Asiatic cheetah was investigated from 2004 to 2009 in northeastern Iran where prey population has been depleted due to poaching. The survey was mainly based on scat analysis, complemented by kill monitoring and local inquiries of direct observations. Results of the research revealed that the Asiatic cheetahs mainly rely on medium-sized ungulates. However, with respect to low density of gazelles, they catch a considerable proportion of their food demands based on livestock which brings the cheetahs in direct conflict with local people. Meanwhile, smaller mammals only meet a small proportion of cheetah's diet. Our data indicate high importance of enhancing conservation efforts in northeastern Iran as well as other cheetah habitats where normal prey ungulates have experienced severe decline.
... Food habit studies can be based on tracking to predation sites, stomach and intestinal content analysis, and scat analysis. Scat analysis is the method primarily employed for studying carnivore diets (Goodbois et al. 2005). Scat collection can be non-invasive and cost-effective, while analysis of scat contents provides an accurate estimate of dietary habits (Ciucci et al. 1996(Ciucci et al. , 2004. ...
... prey species and thus bias diet composition. For example, scats from bobcats (Lynx rufus) containing deer remains experienced a larger mass loss than scats containing mice and rats or rabbits when left in the field for three weeks, reducing the likelihood for scats containing deer to be reliably recognised as bobcat scats [30]. The choice of interval between collecting scats should therefore ensure that a scat can be reliably allocated to the carnivore species under study. ...
The diet of free-ranging carnivores is an important part of their ecology. It is often determined from prey remains in scats. In many cases, scat analyses are the most efficient method but they require correction for potential biases. When the diet is expressed as proportions of consumed mass of each prey species, the consumed prey mass to excrete one scat needs to be determined and corrected for prey body mass because the proportion of digestible to indigestible matter increases with prey body mass. Prey body mass can be corrected for by conducting feeding experiments using prey of various body masses and fitting a regression between consumed prey mass to excrete one scat and prey body mass (correction factor 1). When the diet is expressed as proportions of consumed individuals of each prey species and includes prey animals not completely consumed, the actual mass of each prey consumed by the carnivore needs to be controlled for (correction factor 2). No previous study controlled for this second bias.
Here we use an extended series of feeding experiments on a large carnivore, the cheetah (Acinonyx jubatus), to establish both correction factors. In contrast to previous studies which fitted a linear regression for correction factor 1, we fitted a biologically more meaningful exponential regression model where the consumed prey mass to excrete one scat reaches an asymptote at large prey sizes. Using our protocol, we also derive correction factor 1 and 2 for other carnivore species and apply them to published studies. We show that the new method increases the number and proportion of consumed individuals in the diet for large prey animals compared to the conventional method.
Our results have important implications for the interpretation of scat-based studies in feeding ecology and the resolution of human-wildlife conflicts for the conservation of large carnivores.
Context Reliable, cost-effective monitoring methods are essential for managing wildlife populations. Scat-and-sign surveys (i.e. monitoring defecation, animal scratching, footprints, food remains) are a rapid, low-cost, non-invasive monitoring approach, but unquantified biases and uncertainties associated with these methods have caused researchers to doubt their reliability. Aims We sought to quantify how richness, occupancy and activity estimates derived from a long-term camera-trap study differed from those of scat surveys in the same locations, to determine scat-survey reliability and model bias corrections. Methods We used transect-based scat surveys at 110 sites in the temperate forests of southern Tasmania (Australia), to estimate occupancy, activity and community richness for common, ground-dwelling vertebrates. These results were compared with estimates derived from a long-term passive camera-trap study at the same sites. In addition, time-lapse imagery taken with the camera traps was used to monitor the persistence of rufous-belled pademelon (Thylogale billardierii) and Tasmanian devil (Sarcophilus harrisii) scats in relation to environmental correlates. Key results Scat persistence differed between these two species. The half-life of S. harrisii scats was 113 days, compared with 63 days for T. billardierii. Generalised linear modelling showed that scat surveys were most efficacious at sites with little disturbance and homogenous substrates. Overall, scat surveys consistently underestimated site occupancy and richness relative to the camera traps (μ = 2.7:1), but this bias was inconsistent, with the ratio exceeding 15 for the arboreal brushtail possum (Trichosurus vulpecula). Scats were most reliably detected for large, trail-using mammals such as S. harrisii, T. billardierii, and common wombat (Vombatus ursinus). Scat surveys were less useful for the surveillance of low-density and arboreal species. Scats were uncommon for the two bird species examined, but alternative superb lyrebird (Menura novaehollandiae) signs were detected reliably. Conclusions Scat surveys reliably detected large, trail-using mammals. However, estimates of activity were poorly correlated between camera traps and scat surveys. Implications When used appropriately, scat surveys can provide an effective and cheap ‘snapshot’ index for wildlife monitoring, especially if the species-specific biases have been calibrated for the vertebrate community and environment under monitoring.
Canis latrans (Coyote) is regarded as a classic generalist predator that has recently established large populations throughout the southeastern US. To better understand how Coyote food habits in the Southeast may differ on an extremely small spatial scale, we collected a total of 305 Coyote scats from 2009 to 2011 on 2 islands separated by a 1.4-2.5-km-wide expanse of low saltwater-marsh on the coast of Georgetown, SC. We identified diagnostic remains of prey items to the lowest possible taxonomic level. A multi-response permutation procedure revealed differences in Coyote diet composition between islands (A = 0.0090, P < 0.0001). Subsequent indicator-species analysis revealed a total of 4 food items that served to differentiate diet between islands: birds. Sus scrofa (Wild Hog), Ilex sp. (holly) fruit, and lagomorphs. Our results demonstrate that Coyote food habits and their potential ecosystem effects may vary widely on a very local scale. This finding may be of particular concern to biologists attempting to utilize published diet studies to inform Coyote management strategies. Our study also documented some of the highest levels of bird consumption by Coyotes published to date; we detected bird remains found in 42.45-59.80% of scats.
Estudié las relaciones ecologias de 10 gatos montés (Lynx rufus; cuatro machos, seis hembras) de una población no explotada en el desierto Chihuahua del sur de Nuevo Mexico durante 2004–2008. Los rangos de hogar anuales fueron 12,887 ha para machos y 2,847 ha para hembras, usando el método de «adaptive kernel» al 95%. Los niveles medios de actividad durante la noche y el día fueron 80.6 y 18.8%, respectivamente. El conejo Sylvilagus audubonii fue la especie de presa más común encontrada en las heces. La tasa de supervivencia anual fue 0.875 para machos y 0.917 para hembras. El peso medio de machos y hembras fue 12.6 y 9.0 kg, respectivamente. Dos gatos montés resultaron positivos por toxoplasmosis. Comparados con los de otras áreas, los gatos montés de este estudio fueron más pesados, hubo más contraste entre los niveles de actividad de la noche y del día, y los machos tuvieron rangos de hogar más grandes. La tasa de supervivencia fue semejante a la de otras poblaciones no explotadas.
Feces were analyzed to determine the food habits of coyotes (Canis latrans) in Guyamaca Rancho State Park, San Diego Co., Galifornia. Of 748 food items identified from 223 scats, mammals made up 53 %, vegetation 23 %, arthropods 9%, reptiles 1%, birds 1% and miscellaneous items 3%. Percent relative frequency of mammalian food items decreased significantly from winter (78%) to summer (52%). Conversely percent of arthropod remains in summer scats (11%) increased significantly from winter scats (0%). Percent occurrence of vegetation in feces also increased significantly from winter (12%) to summer (22%). Observations of coyotes did not vary significantly between seasons. These results suggest that coyotes feed opportunistically in Guyamaca Rancho State Park.
Diets of cougars (Felis concolor) were studied from December 1978 to August 1981, on a 4,500-km2 study area near Escalante, Utah. Prey eaten by cougars was estimated from analysis of 112 animals consumed as prey and from 239 cougar scats. Composition of diet was corrected based on feeding trials using captive cougars. Mule deer (Odocoileus hemionus) were found to be the major prey item, 81% of biomass consumed. Lagomorphs, large rodents, and smaller predators were also important components of the diet. Cattle comprised less than 1% of the diet, although they were abundant on the cougars' summer range. Age structure of deer killed by cougars indicated that older (>7 years) deer were killed more often than expected (P < 0.005).
In 9 trials, captive wolves (Canis lupus) were fed prey varying in size from snowshoe hares (Lepus americanus) to adult deer (Odocoileus virginianus), and the resulting scats were counted. Field-collectible scats were distinguished from liquid, noncollectible stools. In collectible scats, the remains of small prey occurred in greater proportion relative to the prey's weight, and in lesser proportion relative to the prey's numbers, than did the remains of larger prey. A regression equation with an excellent fit to the data (r2 = 0.97) was derived to estimate the weight of prey eaten per collectible scat for any prey. With this information and average prey weights, the relative numbers of different prey eaten also can be calculated.
Food habits of bobcats (Lynx rufus) in eastern Tennessee were determined from analyzing 176 cat samples collected on the Oak Ridge National Environmental Research Park. Remains of cottontail rabbits (Sylvilagus floridanus) were the most frequently occurring food item. White-tail deer (Odocoileus virginianus) and pine vole (Microtus pinetorum) remains also were found frequently in samples. Data obtained from this study indicated that food preferences for bobcats in eastern Tennessee are similar to those in other southeastern states where the habitat is similar to the Oak Ridge area and somewhat different from those with significantly different habitat.
Recovery of rodent bone and teeth from coyote (Canis latrans) scats (feces) varied with prey size, meal size, energy content of the meal, and the frequency with which prey were consumed. Mean percentages of mouse and rat teeth recovered ranged from 1% (SE = 0.5%, n = 5) to 24.4% (SE = 3.6%, n = 4) and from 13.8% (SE = 3.8%, n = 5) to 52.5% (SE = 16.6%, n = 5), respectively. A significant portion of this variation resulted from physiological mechanisms affecting how long prey were retained in the digestive acids of the stomach. Recovery of hair did not vary and thus it was considered to be nondigestible. Owing to the variation in the recovery of bone and teeth and the lack of variation in the recovery of hair, we recommend the use of teeth or bone to identify the small rodents present in carnivore seats, and then the use of a visual estimate of hair, or sample of hair, to apportion the seat to the prey items present. We caution against using the numbers of teeth or diagnostic bones to determine the number or amount of a prey item represented by a seat without addressing the variability in their recovery. The effects of gastrointestinal physiology should be considered when planning feeding trials to derive correction factors for seat analysis.
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