Article

Towards a behavioral ecology of ecological landscapes

March 1996
Trends in Ecology & Evolution 11(3):131-5

March 1996
11(3):131-5

DOI:10.1016/0169-5347(96)81094-9

Source
PubMed

Authors:

Patrick A. Zollner

Purdue University

Recent developments in landscape-level ecological modeling rest upon poorly understood behavioral phenomena. Surprisingly, these phenomena include animal movement and habitat selection, two areas with a long history of study in behavioral ecology. A major problem in applying traditional behavioral ecology to landscape-level ecological problems is that ecologists and behaviorists work at very different spatial scales. Thus a behavioral ecology of ecological landscapes would strive to overcome this inopportune differential in spatial scales. Such a landscape-conscious behavioral undertaking would not only establish more firmly the link between behavior and ecological systems, but also catalyze the study of basic biological phenomena of Interest to behaviorists and ecologists alike.

The effect of patch distance, matrix type and experience on habitat perception and flight speed of two species of Heliconius butterflies

Article

Dec 2023

The perceptual range of an organism is the distance at which landscape elements are recognised by it. Estimates of this sensory trait are relevant to understand how organisms recognise suitable habitat within fragmented landscapes. We investigated how the nature of inhospitable environments (matrix) neighbouring a forest patch and adult experience (lab‐raised naïve vs. free‐flying experienced adults) affect the perceptual range and flight speed of the forest butterfly species Heliconius erato and Heliconius melpomene . In field experiments, butterflies were released at various distances from the edge of the habitat patch. Flight orientation and speed were evaluated. In one experiment, wild‐caught individuals of H. erato and H. melpomene were released in two matrix types, a coconut plantation and an open field. In a subsequent experiment, lab‐raised naïve H. erato was released at the same site. Release distance was the best predictor of butterfly behaviour for the two species. Individuals released up to 60 m successfully oriented towards the habitat patch, indicating a perceptual range below 100 m. Flight speed was higher the closer a butterfly was released to the edge. Matrix type did not affect butterfly orientation within its perceptual range distance. We did not find a significant effect of experience on butterfly orientation. Our study shows that the perceptual distance of Heliconius is within the range of known estimates from other butterfly species. Within this range, and irrespective of matrix type and experience, individuals were capable of orienting towards their preferred habitat and at flight speeds that were related to the distance of release.

Forced sympatry? Spatiotemporal interactions of ursids, the Himalayan brown bear and the Asiatic black bear along a gradient of anthropic disturbances in Western Himalaya

Article

Jun 2023
J ZOOL

The study sheds light on the spatiotemporal behavior of two bear species and reveals their sympatric and allopatric relationships in two different anthropogenic environments. Brown bear was forced to use suboptimal habitats due to high anthropogenic pressures, also increasing their co-occurrence with Asiatic black bear. The study showed that in addition to biological factors, anthropogenic pressures may also influence interspecific interactions. We emphasize on preserving diverse habitats and characterization of species requirements across different niche.

Dispersal limitation predicts the spatial and temporal filtering of tropical bird communities in isolated forest fragments

Article

Full-text available

Nov 2023
FUNCT ECOL

The link between dispersal traits and patterns of community assembly remains a frontier in understanding how vertebrate communities persist in fragmented landscapes. Using experimental release trials and intensive field surveys of bird communities in fragmented forests of the Peruvian and Colombian Andes, we demonstrate that morphological traits related to movement (1) predict experimental flight performance and (2) exhibit dispersal‐mediated environmental filtering at the community scale. After correcting for body size, four traits hypothesised to influence flight ability (wing length, wing pointedness, wing loading, and eye size) predicted distance flown across a hostile experimental landscape, with successful species having significantly longer pointed wings, carrying less mass per unit wing area (i.e. lower wing loading), and having smaller eyes. Species with larger eyes also displayed increased flight latency, potentially due to disability glare. At the community scale, we detected a gradient of dispersal‐mediated environmental filtering in fragments compared to reference forest within the same landscape, with relative differences in trait values explained by the temporal and spatial extent of patch isolation. In the Colombian landscape where fragments had been isolated for >60 years, communities were filtered for species with long and narrow wings and small eyes, especially within the most spatially isolated fragments. We observed the opposite pattern in the more recently fragmented Peruvian landscape (15–30 years): communities within fragments tended to have shorter and more rounded wings compared to those in nearby contiguous forests, suggesting that dispersal‐limited species accumulate in the initial years following patch isolation due to “restricted dispersal” and represent an extinction debt yet to be paid. Our results (1) experimentally validate the use of morphological traits as proxies for movement ability in fragmented landscapes, (2) demonstrate that visual acuity functions as a novel dimension of dispersal limitation and (3) quantify how the spatial and temporal components of patch isolation produce a gradient in dispersal‐mediated environmental filtering and extinction debt for communities inhabiting fragments. Read the free Plain Language Summary for this article on the Journal blog.

Response to drift kelp is modified by both substratum and season: green sea urchin foraging behaviour in subsidized habitats

Article

May 2023

The ability of organisms to detect, locate and navigate to resource patches is modified by the surrounding landscape. Green sea urchins Strongylocentrotus droebachiensis in barren grounds exist in a food-limited state and are subject to intense competition. Rapid detection and consumption of resource patches, particularly pieces of macroalgae from adjacent algal beds, are key in determining individual growth, survival and reproductive success. Detection and movement to resource patches requires moving through a heterogeneous benthic seascape composed of rocky and sandy patches, presenting different degrees of resistance to movement. We used time-lapse photography to describe the foraging behaviour of urchins in relation to the presence of a key resource subsidy (drift kelp) and different benthic seascapes. We demonstrated that urchins could detect the presence of drift kelp in barren-ground habitats and alter their movement behaviour in response, but did not exhibit the ability to directionally navigate towards kelp in field conditions. Seascapes with increased proportions of rocky substrata facilitated increased movement in response to the presence of drift. Moreover, urchin foraging behaviour was temporally variable, with no response to the presence of drift in early spring (May). This indicates not only that interpretations of observations of urchin behaviour must take intrinsic and extrinsic seasonal dynamics into account, but that extrapolating results to explain larger-scale patterns and processes must include both spatially explicit subtidal seascapes and temporal dynamics. In many temperate and boreal regions, this indicates the need for increased subtidal benthic research in the fall and winter.

Maintaining and restoring connectivity in landscapes fragmented by roads

Chapter

Nov 2006

One of the biggest threats to the survival of many plant and animal species is the destruction or fragmentation of their natural habitats. The conservation of landscape connections, where animals, plants, and ecological processes can move freely from one habitat to another, is therefore an essential part of any new conservation or environmental protection plan. In practice, however, maintaining, creating, and protecting connectivity in our increasingly dissected world is a daunting challenge. This fascinating volume provides a synthesis on the current status and literature of connectivity conservation research and implementation. It shows the challenges involved in applying existing knowledge to real-world examples and highlights areas in need of further study. Containing contributions from leading scientists and practitioners, this topical and thought-provoking volume will be essential reading for graduate students, researchers, and practitioners working in conservation biology and natural resource management.

Central-place foraging, crop yield, and population change in bees: A study in canola agroecosystems

Thesis

Full-text available

Oct 2019

Samuel V.J. Robinson

Canola (Brassica napus L.) is a valuable crop that occupies a large part of the Canadian prairies, and is visited by wild and managed bees. However, the distribution of foraging bees in mass-flowering crops (MFCs), the value of bee visitation, and how MFCs and semi-natural land (SNL) affect wild bee populations in the context of canola agro-ecosystems is unclear. Using three separate studies, I related pollination and yield to bee visitation, and landscape composition and canola abundance to wild bee abundance. The first study examines honey bee (Apis mellifera L.) visitation in commodity canola fields using a simulation model, and reveals that honey bees most closely followed predictions for solitary efficiency-maximizers, valuing nearby flower sources much more than distant ones. The second study relates visita-tion rates of honey bees and alfalfa leafcutting bees (Megachile rotundata (Fabr.)) to pollen deposition and seed production using a structural equation model. Leafcutter bee visitation strongly increased pollen deposiion, but not honey bee visitation, and extra pollen deposition increased seed production in seed canola, but not in commodity canola. The final study uses solitary bee abundance data from a set of landscapes across southern Alberta, and relates bee abundance to landscape composition from the current and previous year. While the overall response of bee abundance to SNL was positive, individual species' response to SNL ranged from positive to negative, and canola had little effect on any species' abundances. These results reveal that insect visitation in flowering crops decay rapidly with distance, that the plant growth context of canola is equally important as the pollination context, and that while the effect of SNL on wild bee abundance is generally positive, it likely varies depending on the traits of individual bee species. This work provides mechanistic insight into the foraging behaviour and contextual value of pollination by managed bees, and sheds light on how agro-ecological landscapes shape wild bee communities.

Movement with meaning: integrating information into meta‐ecology

Article

Feb 2022

Fluxes of matter, energy and information over space and time contribute to ecosystems' functioning and stability. The meta‐ecosystem framework addresses the dynamics of ecosystems linked by these fluxes but, to date, has focused solely on energy and matter. Here, we synthesize existing knowledge of information's effects on local and connected ecosystems and demonstrate how new hypotheses emerge from the integration of ecological information into meta‐ecosystem theory. We begin by defining information and reviewing how it flows among ecosystems to affect connectivity, local ecosystem function and meta‐ecosystem dynamics. We focus on the role of semiotic information: that which can reduce an individual's – or a group's – uncertainty about the state of the world. Semiotic information elicits behavioral, developmental and life history responses from organisms, potentially leading to fitness consequences. Organisms' responses to information can ripple through trophic interactions to influence ecosystem processes, their local and regional dynamics, and the spatiotemporal flows of energy and matter, therefore information should affect meta‐ecosystem dynamics such as stability and productivity. While specific subdisciplines of ecology currently consider different types of information (e.g. social and cultural information, natural and artificial light or sound, body condition, genotype and phenotype), many ecological models currently account for neither the spatio–temporal distribution of information nor its perception by organisms. We identify the empirical, theoretical and philosophical challenges in developing a robust information meta‐ecology and offer ways to overcome them. Finally, we present new hypotheses for how accounting for realistic information perception and responses by organisms could impact processes such as home range formation and spatial insurance, and thus our understanding of ecological dynamics across spatial and temporal scales. Accounting for information will be essential to understanding how dynamics such as fitness, organismal movement and trophic interactions influence meta‐ecosystem functioning, and predicting how ecosystem processes are affected by anthropogenic pressures.

Can attraction to and competition for high‐quality habitats shape breeding propensity?

Article

Full-text available

Feb 2022

In many animal species, sexually mature individuals may skip breeding opportunities despite a likely negative impact on fitness. In spatio‐temporally heterogeneous environments, habitat selection theory predicts that individuals select habitats where fitness prospects are maximized. Individuals are attracted to high‐quality habitat patches where they compete for high‐quality breeding sites. Since failures in contests to secure a site may prevent individuals from breeding, we hypothesized that attraction to and competition for high‐quality habitats could shape breeding propensity. Under this hypothesis, we predicted the two following associations between breeding propensity and two key population features. (1) When mean habitat quality in the population increases in multiple patches such that availability of high‐quality sites increases across the population, the resulting decrease in competition should positively affect breeding propensity. (2) When the number of individuals increases in the population, the resulting increase in competitors should negatively affect breeding propensity (negative density dependence). Using long‐term data from kittiwakes Rissa tridactyla , we checked the prerequisite of prediction (1), that availability of high‐quality sites is positively associated with current mean habitat quality in the population (represented by breeding success). We then applied integrated population modelling to quantify annual fluctuations in population mean breeding success, breeding propensity and number of individuals by breeding status (pre‐breeders, breeders, skippers and immigrants), and tested our predictions. Our results showed that breeding propensity acts as an important driver of population growth. As expected, breeding propensity was positively associated with preceding mean habitat quality in the population, and negatively with the number of competitors. These relationships varied depending on breeding status, which likely reflects status dependence in competitive ability. These findings highlight the importance of competition for high‐quality breeding sites in shaping breeding propensity. Thereby, we draw attention towards alternative and complementary explanations to more standard considerations regarding the energetic cost of reproduction, and point to possible side effects of habitat selection behaviours on individual life histories and population dynamics.

Temporal–spatial variability of grazing behaviors of yaks and the drivers of their intake on the eastern Qinghai-Tibetan Plateau

Article

Full-text available

Jun 2024

Introduction Grassland-livestock balance is an important principle of sustainable development of grassland livestock production and grassland ecosystem health. Grassland degradation becomes more serious at global scales and especially at the area that is sensitive to climate change and human activities. Decreases in pasture biomass and shifts in plant community composition in degraded grasslands can largely affect grazing behaviors of livestock. Up to date, however, it is unclear that whether livestock behaviors change across spatial and temporal scales and what key factors are to shape observed behavioral patterns of livestock. Methods Here, yak behaviors including grazing, rumination and walking on the eastern Qinghai-Tibetan Plateau (QTP) were monitored by a continuous visual observation, to investigate temporal and spatial variations of grazing behavior of yaks (Bos grunniens); based on the data from public database in the past 18 years, a meta-analysis was conducted to examine the main factors that affect grazing behaviors and intake of yaks. Results We showed that grazing behaviors of yaks differed significantly within hours, among hours of each day and among days as well as across different observation sites. Intake rate of yaks was higher in the morning than in the afternoon, but walking speed showed an inverse trend compared with intake rate. Resting, altitude, the mean annual precipitation (MAP), the mean annual temperature (MAT), forage ash, yak age and season were the main predictors for yak intake, and forage and yak individual characteristics had direct effects on grazing behaviors and intake of yaks. Discussion The findings confirm that grazing behaviors of yaks can vary even at small temporal scales and regional scales, which is closely related to the shift in forage quality and biomass caused by environmental changes. The study suggests that multiple factors can be responsible for the variation in livestock behaviors and shifts in behavioral patterns may consequently lead to positive or negative feedback to grassland ecosystems through plant-animal interactions.

Scale-dependent habitat selection is shaped by landscape context in dispersing white-tailed deer

Article

Full-text available

Mar 2024
LANDSCAPE ECOL

Context Identifying how animals select habitat while navigating landscapes is important for understanding behavioral ecology and guiding management and conservation decisions. However, habitat selection may be spatially and temporally plastic, making it challenging to quantify how species use resources across space and time. Objectives We investigated how landscape context and dispersal shape habitat selection at multiple spatial scales in white-tailed deer (Odocoileus virginianus). Methods Using step-selection functions, we quantified habitat selection of landcover and topographic covariates at three spatial scales for juvenile males during three movement periods (before, during, after dispersal) in two regions of Missouri, USA—a fragmented, low forest cover region with rolling hills, and a forested, topographically variable region. Results Although selection for forest cover increased after dispersal in both regions, deer selected forest cover at smaller spatial scales in the fragmented, low forest cover region. This result indicates scale of selection was dependent on forest availability and configuration with deer likely perceiving landscapes differently across their distribution. Functional responses to topography differed in magnitude and direction between regions with deer avoiding roads and selecting valleys in the rolling hills region (especially during dispersal) while showing no response to roads and selecting for ridgelines (during dispersal) in the topographically variable region. This result suggests movement behavior is strongly dependent on topography. Conclusions Although deer may select similar habitats among regions, landscape context and movement period shape the scale, strength, and direction of selection. This result has important implications for how animals use landscapes across different regional contexts.

Exploratory Behavior in Brown-Headed Nuthatches May Indicate Successful Population Reintroduction Strategy

Thesis

Full-text available

May 2019

Mary Mack Gray

One factor emerging as an important potential determinant of reintroduction and invasion success by wildlife in novel habitats is animal personality. Also called behavioral syndromes, personality is heritable, in part, and can influence dispersal tendency and success, habitat selection, reproductive output and access to critical resources. One axis of personality, emerging as a key predictor of animal survival in new environments, is exploration, often expressed as the rate at which an animal explores a novel environment. Slow exploring individuals often survive better in novel habitats compared with fast explorers. In order to test the hypothesis that slow exploration is favored in a novel environment, I compared exploratory behavior in three Brown-headed Nuthatch (Sitta pusilla) populations: a reintroduced population, the population from which the reintroduced birds originated (original donor), and a distant control population. I predicted that the reintroduced population would exhibit significantly slower exploration in a novel environment test. I placed birds in an exploratory chamber and compared the number of flights/hops, scanning events, thoroughness of exploration, and other movement behaviors in each population. I found that birds from the reintroduced population were significantly slower explorers than the other two populations (based on flights/hops, scanning, and highest proportion of birds that remained frozen in place). My findings confirm a shift in personality type toward slow exploration in the 20 years since reintroduction, adding to the growing consensus that slower explorers fare better in novel environments.

Foray movements are common and vary with natal habitat for a highly mobile bird

Article

Full-text available

Feb 2024

Understanding dispersal is central to interpreting the effects of climate change, habitat loss and habitat fragmentation, and species invasions. Prior to dispersal, animals may gather information about the surrounding landscape via forays, or systematic, short‐duration looping movements away from and back to the original location. Despite theory emphasizing that forays can be beneficial for dispersing organisms and that such behaviors are predicted to be common, relatively little is known about forays in wild populations. Theory predicts that individuals that use forays may delay dispersal and such behaviors should increase survival, yet empirical tests of these predictions remain scarce. We tested these predictions in a natural system using the critically endangered snail kite ( Rostrhaumus sociabilis ), a wetland‐dependent raptor. We GPS tracked 104 snail kites from fledging through emigration from the natal site across their breeding range to understand the demographic consequences of movement. We found that forays were common (82.7% of individuals tracked), and natal habitat played an important role in the initiation, execution, and outcome of foray behavior. The effect of foraying on survival was indirect, where forayers emigrated later than non‐forayers, and individuals that emigrated later had the highest survival. Poor hydrological conditions in the natal environment were especially important for eliciting forays. Finally, females responded more strongly to natal hydrology than males, making more forays and significantly longer, more distant trips. These results emphasize the fundamental role of natal habitat for determining behavioral patterns, strengthen links between individual movement decisions and their demographic consequences, and provide an important behavioral focal point for interpreting movement tracks that would not otherwise be captured by conventional movement models.

Habitat configuration influences mammal populations at a wider spatial extent than habitat composition: a meta-analysis of forest mammal datasets

Preprint

Full-text available

May 2023

Context The spatial extent at which landscape variables most strongly influences wildlife populations (i.e., scale of effect) is of key importance to ecology and conservation. Many factors can influence scales of effect, but these relationships are poorly understood. In particular, the way scales of effect vary with different landscape metrics has not been extensively tested. Objectives Our study examined whether metrics of landscape configuration have wider or narrower scales of effect than habitat composition. We also examined how a variety of factors (i.e., species traits and landscape context) influence the magnitude of these differences in scales of effect between metrics. Methods We calculated scales of effect for four metrics of habitat configuration and one metric of composition directly from species presence/absence data in online repositories. We did so for 102 species of mammals from 33 studies across the globe. Results Two metrics of configuration had significantly wider scales of effect than habitat composition, while the difference between the other two metrics of configuration and composition were not significant. The magnitude of the difference between metrics varied among samples, but none of the factors tested explained this variability. Conclusions If the scale of effect of a metric of composition is known, then a metric of configuration’s scale of effect can be expected to be roughly 15–20% wider. However, this pattern may not hold for metrics of configuration that do not measure attributes of the landscape that mediate species dispersal or that are correlated with the metric of composition.

Movement ecology of an endangered mesopredator in a mining landscape

Article

Full-text available

Jan 2024

Background Efficient movement and energy expenditure are vital for animal survival. Human disturbance can alter animal movement due to changes in resource availability and threats. Some animals can exploit anthropogenic disturbances for more efficient movement, while others face restricted or inefficient movement due to fragmentation of high-resource habitats, and risks associated with disturbed habitats. Mining, a major anthropogenic disturbance, removes natural habitats, introduces new landscape features, and alters resource distribution in the landscape. This study investigates the effect of mining on the movement of an endangered mesopredator, the northern quoll (Dasyurus hallucatus). Using GPS collars and accelerometers, we investigate their habitat selection and energy expenditure in an active mining landscape, to determine the effects of this disturbance on northern quolls. Methods We fit northern quolls with GPS collars and accelerometers during breeding and non-breeding season at an active mine site in the Pilbara region of Western Australia. We investigated broad-scale movement by calculating the movement ranges of quolls using utilisation distributions at the 95% isopleth, and compared habitat types and environmental characteristics within observed movement ranges to the available landscape. We investigated fine-scale movement by quolls with integrated step selection functions, assessing the relative selection strength for each habitat covariate. Finally, we used piecewise structural equation modelling to analyse the influence of each habitat covariate on northern quoll energy expenditure. Results At the broad scale, northern quolls predominantly used rugged, rocky habitats, and used mining habitats in proportion to their availability. However, at the fine scale, habitat use varied between breeding and non-breeding seasons. During the breeding season, quolls notably avoided mining habitats, whereas in the non-breeding season, they frequented mining habitats equally to rocky and riparian habitats, albeit at a higher energetic cost. Conclusion Mining impacts northern quolls by fragmenting favoured rocky habitats, increasing energy expenditure, and potentially impacting breeding dispersal. While mining habitats might offer limited resource opportunities in the non-breeding season, conservation efforts during active mining, including the creation of movement corridors and progressive habitat restoration would likely be useful. However, prioritising the preservation of natural rocky and riparian habitats in mining landscapes is vital for northern quoll conservation.

Habitat configuration influences mammal populations at a wider spatial extent than habitat composition: a meta-analysis of forest mammal datasets

Article

Full-text available

Jan 2024
LANDSCAPE ECOL

Context The spatial extent at which landscape variables most strongly influences wildlife populations (i.e., scale of effect) is of key importance to ecology and conservation. Many factors can influence scales of effect, but these relationships are poorly understood. In particular, the way scales of effect vary with different landscape metrics has not been extensively tested. Objectives Our study tested whether metrics of landscape configuration have wider or narrower scales of effect than habitat composition. We also examined how species traits and landscape context influence the magnitude of differences in scales of effect between metrics. Methods We calculated scales of effect for four metrics of habitat configuration and one metric of composition directly from species presence/absence data in online repositories including 102 species of forest mammals from 33 studies across the globe. We then compared the magnitudes and variability of scales of effect using Hedge’s g. Results Two metrics of configuration (flux and patch density) had significantly wider scales of effect than habitat composition, while the differences between the other two metrics of configuration and composition were not statistically significant. The magnitude of the difference between metrics varied among samples, but none of the factors tested explained this variability. Conclusions For forest mammals, the scale of effect of a configuration metric can be expected to be 15–20% wider than a composition metric. However, this pattern may not hold for metrics of configuration that do not quantify attributes of the landscape that mediate species dispersal or that are correlated with the metric of composition.

Patrón de actividad diurno de los monos aulladores de manto (Alouatta palliata) y su variación en función de factores climáticos

Thesis

Full-text available

Jun 2023

Maria Pira

An activity pattern describes the frequency, duration and/or sequence of different regular behaviors of an animal. This study describes the pattern of daily activity and its variable association with ambient temperature and rainfall of the mantled howler monkey (Alouatta palliata) in Catemaco, Veracruz, Mexico. The method used was direct observation with a continuous focal sampling (263 hours). The focal individuals were seven adult males of two groups of mantled howler monkeys. The results show that the diurnal activity pattern is generally bimodal, with one peak in the morning and one in the afternoon. Furthermore, the diurnal activity pattern varied significantly as a function of temperature: activity peaks on hot days occurred an hour earlier than peaks on cold days. The occurrence of light in the activity pattern has no significant difference, but the single variable is demonstrated in a trimodal distribution. The results of this study coincide with previous reports for this species and other mammals. Although, contrary as predicted, the influence of the rainfall was not significant in this study. For this reason, it is important to note that climatic factors, in particular ambient temperature, influence the diurnal behavior of mantled howler monkeys. Likewise, these results indicate that more research is required to explore the effects of rainfall on the activity pattern of these primates.

What determines the information update rate in echolocating bats

Article

Full-text available

Nov 2023

The rate of sensory update is one of the most important parameters of any sensory system. The acquisition rate of most sensory systems is fixed and has been optimized by evolution to the needs of the animal. Echolocating bats have the ability to adjust their sensory update rate which is determined by the intervals between emissions - the inter-pulse intervals (IPI). The IPI is routinely adjusted, but the exact factors driving its regulation are unknown. We use on-board audio recordings to determine how four species of echolocating bats with different foraging strategies regulate their sensory update rate during commute flights. We reveal strong correlations between the IPI and various echolocation and movement parameters. Specifically, the update rate increases when the signals’ peak-energy frequency and intensity increases while the update rate decreases when flight speed and altitude increases. We suggest that bats control their information update rate according to the behavioral mode they are engaged in, while always maintaining sensory continuity. Specifically, we suggest that bats apply two modes of attention during commute flights. Our data moreover suggests that bats emit echolocation signals at accurate intervals without the need for external feedback.

Density‐dependent within‐patch movement behavior of two competing species

Article

Full-text available

Nov 2023

Movement behavior is central to understanding species distributions, population dynamics and coexistence with other species. Although the relationship between conspecific density and emigration has been well studied, little attention has been paid to how interspecific competitor density affects another species' movement behavior. We conducted releases of two species of competing Tribolium flour beetles at different densities, alone and together in homogeneous microcosms, and tested whether their recaptures‐with‐distance were well described by a random‐diffusion model. We also determined whether mean displacement distances varied with the release density of conspecific and heterospecific beetles. A diffusion model provided a good fit to the redistribution of T. castaneum and T. confusum at all release densities, explaining an average of >60% of the variation in recaptures. For both species, mean displacement (directly proportional to the diffusion rate) exhibited a humped‐shaped relationship with conspecific density. Finally, we found that both species of beetle impacted the within‐patch movement rates of the other species, but the effect depended on density. For T. castaneum in the highest density treatment, the addition of equal numbers of T. castaneum or T. confusum had the same effect, with mean displacements reduced by approximately one half. The same result occurred for T. confusum released at an intermediate density. In both cases, it was total beetle abundance, not species identity that mattered to mean displacement. We suggest that displacement or diffusion rates that exhibit a nonlinear relationship with density or depend on the presence or abundance of interacting species should be considered when attempting to predict the spatial spread of populations or scaling up to heterogeneous landscapes.

Effects of forest fragmentation on the dietary ecology and activity of a nocturnal lemur community in North West Madagascar

Article

Full-text available

Oct 2023
AM J PRIMATOL

Deforestation and habitat fragmentation is the primary threat to primate populations. The primates that live within degraded and anthropogenically disturbed habitats typical of fragmented landscapes have to cope with lower availability of resources in comparison to primates in continuous, undisturbed forests. While some species are sensitive to forest fragmentation, some evidence exists to suggest that primates can alter their behavior and adapt to such changes, which enables their survival in suboptimal habitat. In this study, we assessed how forest fragmentation and its associated edge-effects impact the feeding ecology and activity levels of a nocturnal primate community in the Sahamalaza-Iles Radama National Park, North West Madagascar. From March 06, 2019 to May 17, 2022, we collected data on tree and invertebrate phenology at our study site, and feeding ecology and activity for 159 lemur individuals from four species. Fruit and flower availability varied significantly between continuous and fragmented forest, and between forest core and edge areas, with continuous forest exhibiting higher continuous fruit and flower availability. Lemur feeding ecology varied significantly too, as the feeding niches of all four species were significantly different between continuous and fragmented forest and between core and edge areas. However, lemur activity levels were mostly consistent among all forest areas. The results of this study suggest that nocturnal lemurs are able to adapt their dietary ecology in response to the available food sources within their habitat. Due to this flexible ecology and dietary plasticity, the lemurs do not need to significantly alter their behavior in different environments to fulfill their dietary needs. While nocturnal lemurs demonstrate adaptability and flexibility to degraded habitat, it is unclear how far this plasticity will stretch considering that Madagascar's forests are still being cleared at an alarming rate. Urgent conservation action is therefore needed to ensure the future of lemur habitat.

Vegetation restoration following dieback of Phragmites australis in the Mississippi River Delta, USA

Article

Oct 2023

The Mississippi River Delta (MRD) is one of the largest wetlands in the world and is experiencing widespread dieback of its most prevalent plant species, Phragmites australis. The potential for revegetation of dieback sites was assessed by planting three genetically distinct lineages of P. australis at seven sites in the MRD that varied in water depth. These lineages include Delta, the most prevalent in the MRD, EU, a highly invasive lineage, and Gulf, a common lineage of the Gulf Coast and southern United States. Three additional wetland species were planted at a subset of these sites. Plantings were monitored for 32 months during which time, we surveyed plantings for survival, growth and infestation by a scale insect that has been implicated in P. australis dieback. Survivorship differed considerably among plant types and by 6 months, Delta, Gulf and California bulrush (Schoenoplectus californicus) had twice the survivorship of the other plant types. By the end of the study, Delta, Gulf and bulrush were the only plant types alive, with Delta persisting in more than twice as many sites and having > 6 times more area of coverage as Gulf and bulrush. For all P. australis lineages, water depth was negatively related to survivorship. Finally, although scale insects achieved twice the abundance on Delta than the other lineages, we found no evidence that scales were inhibiting the growth and survival of P. australis. Despite potential negative legacy effects of dieback, Delta can be used revegetate shallow-water sites within a year following dieback.

Available Forage and the Conditions for Avoiding Predation of the Siberian Roe Deer (Capreolus pygargus) in the Lesser Xing’an Mountains

Article

Full-text available

Oct 2023

Our study focused on quantifying available forage and the conditions for avoiding predation provided within the home ranges of Siberian roe deer (Capreolus pygargus). We conducted transect surveys in both winter and summer–autumn home ranges of the Siberian roe deer in the Tieli Forestry Bureau of the Lesser Xing’an Mountains. Our results revealed significant differences: (1) In terms of the quantity and quality of available forage, the summer–autumn home range had substantially more available forage than the winter home range, with meadows and cornfields showing the highest edible biomass in each, respectively. In terms of forage quality, there were differences in hemicellulose, cellulose, and lignin content between the two ranges. (2) In terms of the conditions for avoiding predation, the winter home range had lower vegetation coverage and greater visibility, making escape strategies more viable. In contrast, the summer–autumn home range had denser vegetation and limited visibility, making hiding strategies more viable. Our study offers comprehensive insights into the available forage and the conditions for avoiding predation, which is crucial for wildlife conservation strategies and habitat management in the region, as it directly informs strategies that address the seasonal forage requirements and predation avoidance of these deer, ultimately enhancing their prospects for survival in the area.

Spatiotemporal patterns of lion ( Panthera leo ) space use in a human–wildlife system

Article

Full-text available

Sep 2023

Conserving large carnivores requires protecting landscape spaces that encompass all spatiotemporal scales of their movement. Large carnivores normally roam widely, but habitat loss and fragmentation can constrain their movement in ways that restrict access to resources and increase encounters with humans and potential conflict. Facilitating carnivore population coexistence with humans across landscapes requires conservation plans informed by patterns of carnivore space use, particularly at the human–wildlife interface. We sought to understand lion space use in Laikipia, Kenya. We conducted a path‐selection function analysis using GPS collar data from 16 lions to assess patterns of space use across a range of spatial scales (sedentary to home range expanses; 0, 12.5, 25 and 50 km) and temporal scales (day, dusk, night and dawn). Path‐selection results were then incorporated into space use maps. We found that most landscape features influenced path‐selection at the broadest spatial scale (50 km), representative of home range‐wide movement, thereby demonstrating a landscape‐wide human impact on lion space use. We also detected sub‐diurnal variation in lion path‐selection which revealed limited space use during daylight hours and increased space use overnight. Our results highlight that optimal support for human–lion coexistence should be temporally adaptive at sub‐diurnal scales. Furthermore, spatial approaches to lion conservation may be better generalized at broad spatial scales so that land management plans can account for home range patterns in lion space use.

Grazing-Induced Cattle Behaviour Modulate the Secondary Production in a Eurasian Steppe Ecosystem

Article

Full-text available

May 2023

Grazing-induced cattle behaviour modulates the secondary production in a Eurasian steppe ecosystem

Article

May 2023
SCI TOTAL ENVIRON

Livestock-grassland interactions are among the most important relationships in grazed grassland ecosystems, where herbivores play a crucial role in plant community and ecosystem functions. However, previous studies primarily have focused on the responses of grasslands to grazing, with few focussing on the effects of livestock behaviour that in turn would influence livestock intake and primary and secondary productivity. Through a 2-year grazing intensity experiment with cattle in Eurasian steppe ecosystem, global positioning system (GPS) collars were used to monitor animal movements, where animal locations were recorded at 10-min intervals during the growing season. We used a random forest model and the K-means method to classify animal behaviour and quantified the spatiotemporal movements of the animals. Grazing intensity appeared to be the predominant driver for cattle behaviour. Foraging time, distance travelled, and utilization area ratio (UAR) all increased with grazing intensity. The distance travelled was positively correlated with foraging time, yielding a decreased daily liveweight gain (LWG) except at light grazing. Cattle UAR showed a seasonal pattern and reached the maximum value in August. In addition, the canopy height, above-ground biomass, carbon content, crude protein, and energy content of plants all affected cattle behaviour. Grazing intensity and the resulting change in above-ground biomass and forage quality jointly determined the spatiotemporal characteristics of livestock behaviour. Increased grazing intensity limited forage resources and promoted intraspecific competition of livestock, which induced longer travelling distance and foraging time, and more even spatial distribution when seeking habitat, which ultimately led to a reduction in LWG. In contrast, under light grazing where there were sufficient forage resources, livestock exhibited higher LWG with less foraging time, shorter travelling distance, and more specialized habitat occupation. These findings support the Optimal Foraging Theory and the Ideal Free Distribution model, which may have important implications for grassland ecosystem management and sustainability.

Unraveling a paradox of habitat relationships: scale-dependent drivers of temporal occupancy-abundance relationships in a cooperatively breeding bird

Article

Full-text available

Apr 2023
LANDSCAPE ECOL

Context Spatial occupancy and local abundance of species often positively covary, but the mechanisms driving this widespread relationship are poorly understood. Resource dynamics and habitat changes have been suggested as potential drivers, but long-term studies relating them to abundance and occupancy are rare. In this 34-year study of acorn woodpeckers (Melanerpes formicivorus), a cooperatively breeding species, we observed a paradoxical response to changes in habitat composition: despite a reduction in the availability of high-quality breeding habitat, the population increased considerably. Objectives We investigated the role of annual variation in food availability and long-term changes in habitat composition as predictors of population dynamics. Methods Using model selection, we contrasted competing hypotheses on the effects of changing resource availability on occupancy and social group size across three spatial scales: territory, neighborhood, and landscape. Results The increase in abundance was largely determined by the formation of new social groups, driven by a landscape-level expansion of canopy cover and its interaction with neighborhood-level acorn abundance, indicative of long-term increases in overall acorn productivity. Group size increased with neighborhood acorn crop two years earlier but groups were smaller in territories with more canopy cover. Conclusions Our results indicate that scale-dependent processes can result in paradoxical relationships in systems with spatial and temporal resource heterogeneity. Moreover, the findings support the role of resources in driving changes in abundance and occupancy at a landscape scale, suggesting that colonization of marginal habitat drives the positive occupancy-abundance relationship in this cooperatively breeding species.

Spatio-Temporal Analysis of Game Harvests in Sweden

Article

Full-text available

Mar 2023
ENVIRON RESOUR ECON

The benefits and costs of wildlife are contingent on the spatial overlap of animal populations with economic and recreational human activities. By using a production function approach with dynamic spatial panel data models, we analyze the effects of human hunting and carnivore predation pressure on the value of ungulate game harvests. The results show evidence of dynamic spatial dependence in the harvests of roe deer and wild boar, but not in those of moose, which is likely explained by the presence of harvesting quotas for the latter. Results suggest the impact of lynx on roe deer harvesting values is reduced by 75% when spatial effects are taken into account. The spatial analysis confirms that policymakers’ aim to reduce wild boar populations through increased hunting has been successful, an effect that was only visible when considering spatial effects.

Habitat detection, habitat choice copying or mating benefits: What drives conspecific attraction in a nomadic songbird?

Article

Full-text available

Nov 2022

Conspecific attraction during habitat selection is common among animals, but the ultimate (i.e. fitness‐related) reasons for this behaviour often remain enigmatic. We aimed to evaluate the following three hypotheses for conspecific attraction during the breeding season in male Wood Warblers ( Phylloscopus sibilatrix ): the habitat detection hypothesis, the habitat choice copying hypothesis and the female preference hypothesis. These hypotheses make different predictions with respect to the relative importance of social and nonsocial information during habitat assessment, and whether benefits accrue as a consequence of aggregation. We tested the above hypotheses using a combination of a 2‐year playback experiment, spatial statistics and mate choice models. The habitat detection hypothesis was the most likely explanation for conspecific attraction and aggregation in male Wood Warblers, based on the following results: (1) males were attracted to conspecific song playbacks, but fine‐scale habitat heterogeneity was the better predictor of spatial patterns in the density of settling males; (2) male pairing success did not increase, but instead slightly decreased, as connectivity with other males (i.e. the number and proximity of neighbouring males) increased. Our study highlights how consideration of the process by which animals detect and assess habitat, together with the potential fitness consequences of resulting aggregations, are important for understanding conspecific attraction and spatially clustered distributions.

Monarch Butterfly Ecology, Behavior, and Vulnerabilities in North Central United States Agricultural Landscapes

Article

Full-text available

Nov 2022
BIOSCIENCE

Abstract The North American monarch butterfly (Danaus plexippus) is a candidate species for listing under the Endangered Species Act. Multiple factors are associated with the decline in the eastern population, including the loss of breeding and foraging habitat and pesticide use. Establishing habitat in agricultural landscapes of the North Central region of the United States is critical to increasing reproduction during the summer. We integrated spatially explicit modeling with empirical movement ecology and pesticide toxicology studies to simulate population outcomes for different habitat establishment scenarios. Because of their mobility, we conclude that breeding monarchs in the North Central states should be resilient to pesticide use and habitat fragmentation. Consequently, we predict that adult monarch recruitment can be enhanced even if new habitat is established near pesticide-treated crop fields. Our research has improved the understanding of monarch population dynamics at the landscape scale by examining the interactions among monarch movement ecology, habitat fragmentation, and pesticide use. https://academic.oup.com/bioscience/advance-article/doi/10.1093/biosci/biac094/6808907

Refining the stress gradient hypothesis for mixed species groups of African mammals

Article

Full-text available

Oct 2022

Species interactions such as facilitation and predation influence food webs, yet it is unclear how they are mediated by environmental gradients. Here we test the stress gradient hypothesis which predicts that positive species interactions increase with stress. Drawing upon spatially-explicit data of large mammals in an African savanna, we tested how predation risk and primary productivity mediate the occurrence of mixed species groups. Controlling for habitat structure, predation risk by lions and primary productivity affected the frequency of mixed species groups in species-specific ways, likely reflecting distinct stress perceptions. To test whether mixed species groups indicate positive interactions, we conducted network analyses for specific scenarios. Under predation risk, dyadic associations with giraffes were more pronounced and metrics of animal networks changed markedly. However, dyadic association and network metrics were weakly mediated by primary productivity. The composition of mixed species groups was associated with similarities in prey susceptibility but not with similarities in feeding habits of herbivores. Especially predation risk favoured the frequency of mixed species groups and pronounced dyadic associations which dilute predation risk and increase predator detection. While our results provide support for the stress gradient hypothesis, they also highlight that the relative importance of stressors is context-dependent.

Seascapes and foraging success: Movement and resource discovery by a benthic marine herbivore

Article

Full-text available

Sep 2022

Spatially concentrated resources result in patch‐based foraging, wherein the detection and choice of patches as well as the process of locating and exploiting resource patches involve moving through an explicit landscape composed of both resources and barriers to movement. An understanding of behavioral responses to resources and barriers is key to interpreting observed ecological patterns. We examined the process of resource discovery in the context of a heterogeneous seascape using sea urchins and drift kelp in urchin barrens as a model system. Under field conditions, we manipulated both the presence of a highly valuable resource (drift kelp) and a barrier to movement (sandy substratum) to test the interacting influence of these two factors on the process of resource discovery in barren grounds by urchins. We removed all foraging urchins (Strongylocentrotus droebachiensis) from replicate areas and monitored urchin recolonization and kelp consumption. We tested two hypotheses: (1) unstable substratum is a barrier to urchin movement and (2) the movement behavior of sea urchins is modified by the presence of drift kelp. Very few urchins were found on sand, sand was a permeable barrier to urchin movement, and the permeability of this barrier varied between sites. In general, partial recolonization occurred strikingly rapidly, but sand slowed the consumption of drift kelp by limiting the number of urchins. Differences in the permeability of sand barriers between sites could be driven by differences in the size structure of urchin populations, indicating size‐specific environmental effects on foraging behavior. We demonstrate the influence of patchy seascapes in modulating grazing intensity in barren grounds through modifications of foraging behavior. Behavioral processes modified by environmental barriers play an important role in determining grazing pressure, the existence of refuges for new algal recruits, and ultimately the dynamics of urchin‐algal interactions in barren grounds. We examined the process of resource discovery in the context of a heterogeneous seascape using sea urchins and drift kelp as a model system and modifying the seascape through the addition of sand barriers. Very few urchins were found on the sand, sand was a permeable barrier to urchin movement, and the permeability of this barrier varied between sites. Behavioural processes modified by the environment play an important role in determining grazing pressure, the existence of refuges for new algal recruits, and ultimately the dynamics of urchin‐algal interactions.

Alternations in the foraging behaviour of a primary consumer drive patch transition dynamics in a temperate rocky reef ecosystem

Article

Full-text available

Jun 2022
ECOL LETT

Understanding the role of animal behaviour in linking individuals to ecosystems is central to advancing knowledge surrounding community structure, stability and transition dynamics. Using 22 years of long-term subtidal monitoring, we show that an abrupt outbreak of purple sea urchins (Strongylocentrotus purpuratus), which occurred in 2014 in southern Monterey Bay, California, USA, was primarily driven by a behavioural shift, not by a demographic response (i.e. survival or recruitment). We then tracked the foraging behaviour of sea urchins for 3 years following the 2014 outbreak and found that behaviour is strongly associated with patch state (forest or barren) transition dynamics. Finally, in 2019, we observed a remarkable recovery of kelp forests at a deep rocky reef. We show that this recovery was associated with sea urchin movement from the deep reef to shallow water. These results demonstrate how changes in grazer behaviour can facilitate patch dynamics and dramatically restructure communities and ecosystems.

ABUNDANCIA ESPACIAL DEL ICTIOPLANCTON EN EL CAÑO MÁNAMO

Article

Full-text available

Jan 2013

RESUMEN: El análisis de la variación espacial de la abundancia del ictioplancton permite determinar la época e intensidad de los desoves y el uso del hábitat. Se realizaron calados horizontales de ictioplancton durante muestreos bimestrales desde octubre de 2010 hasta abril de 2011 correspondientes a la época de sequía en seis estaciones seleccionadas a lo largo del caño Mánamo que abarcaron las regiones superior, media e inferior del delta del Orinoco. Los márgenes del caño fueron clasificados en cóncavos y convexos, según su geomorfología. En total se colectaron 7862 huevos/1000m 3 y 239433 larvas/1000m 3 de peces. Los mayores valores de ictioplancton se detectaron en diciembre de 2010 con 5057 huevos/1000m 3 y 85125 larvas/ 1000m 3 y febrero de 2011 con 2391 huevos/1000m 3 y 98859 larvas/1000m 3. La estación con mayor número de huevos y larvas fue Isla Misteriosa-delta inferior. El centro del caño presentó mayor abundancia de ictioplancton, seguido por el margen convexo y el margen cóncavo. Los huevos de peces se relacionaron negativamente con la temperatura del agua; las larvas se mostraron asociadas negativamente con la transparencia. En conclusión se determinó la mayor abundancia de ictioplancton en los meses de diciembre de 2010 y febrero de 2011 y espacialmente hubo mayor ocurrencia del ictioplancton en las estaciones del delta inferior, principalmente en el sector del centro del caño. ABSTRACT: Analyzing ichthyoplankton spatial variation is useful to determine spawning time and intensity, as well as patterns of habitat use by fish. During the dry season, from October 2010 to April 2011, bimonthly collections of ichthyoplankton were carried out through the midstream length and along the waters of both banks of the river, topographically classified as concave and convex and comprising six stations selected on the upper and lower sides of the delta strait of Caño Mánamo. A total of 51,944 fish larvae and 1,776 fish eggs were collected. The largest values of icthyoplankton were observed in December 2010 with 1,181 eggs/1000m 3 , and February 2011, with 31,412 larvae/1000m 3. The station with the largest number of eggs was Isla Misteriosa on the lower delta, the midstream current carrying the most abundance of ichthyoplankton, followed first by those on the convex and then by the concave beds along the river banks. The fish eggs related negatively to the water temperature, while the larvae associated negatively with turbidity.

Behavioral Ecology Optimal distributions of central-place foragers: honey bee foraging in a mass flowering crop

Article

Full-text available

Feb 2022
BEHAV ECOL

The ideal-free distribution and central-place foraging are important ecological models that can explain the distribution of foraging organisms in their environment. However, this model ignores distance-based foraging costs from a central place (hive, nest), whereas central-place foraging ignores competition. Different foraging currencies and cooperation between foragers also create different optimal distributions of foragers, but are limited to a simple two-patch model. We present a hybrid model of the ideal-free distribution that uses realistic competitive effects although accounting for distance-based foraging, and test it using honey bees (Apis mellifera L.) foraging in canola fields (Brassica napus L.). Our simulations show that foragers maximizing efficiency (energy prof its ÷ losses) prioritize distance to their aggregation more than those maximizing net-rate (energy prof its ÷ time) , and that social foragers move to more distant patches to maximize group benefits, meaning that social foragers do not approach an ideal-free distribution. Simulated efficiency-maximizers had a hump-shaped relationship of trip times with distance, spending shorter amounts of time in both nearby and faraway patches. Canola fields were far more attractive to simulated foragers than semi-natural areas, suggesting limited foraging on semi-natural lands during the bloom period of canola. Finally, we found that the observed distribution of honey bees in canola fields most closely resembled the optimal distribution of solitary efficiency-maximizers. Our model has both theoretical and practical uses, as it allows us to model central-place forager distributions in complex landscapes as well as providing information on appropriate hive stocking rates for agricultural pollination.

Breeding Behavior of the Wood Warbler in Relation to the Social Environment

Article

Jan 2022

Shannon Luepold

Most animals exist in some type of social environment. The composition of this environment can impact diverse traits and behaviors, and is increasingly recognized as an important modulator of ecological and evolutionary processes. In this thesis, I examine the interplay between spatial and vocal behavior of male Wood Warblers and three different elements of the social environment: conspecific males, conspecific females, and closelyrelated heterospecifics. In Chapter 2, I investigate three hypotheses for conspecific attraction in male Wood Warblers (Phylloscopus sibilatrix): the habitat location cues hypothesis, the habitat quality cues hypothesis, and the female preference hypothesis. The habitat location cues hypothesis posits that the presence of conspecifics provides social information that indicates the location of potentially suitable habitat, and is thus useful during the search phase of habitat selection. The habitat quality cues hypothesis suggests that conspecific presence provides social information that the local habitat is suitable, and is thus useful during the assessment phase of habitat selection. The female preference hypothesis proposes that males are attracted to settle near conspecifics because females prefer to mate with males in aggregations. My colleagues and I used a combination of a two-year playback experiment, spatial point process models and mate choice models to test the above hypotheses. The results showed that spatial variation in habitat quality was a better predictor of male settlement patterns than proximity to simulated conspecifics, and that aggregated males were not more successful in attracting females. Taken together, the results are most consistent with the habitat location cues hypothesis. In Chapter 3, I explore the relationship between the within-season movements of male birds and mate searching. I suggest that mate searching may be a conceptual framework that can unify temporary movements associated with polyterritoriality and extra-territorial forays as well as permanent movements associated with breeding dispersal. I test four predictions derived from this framework by analyzing the relationship between emigration decisions of male Wood Warblers, ecological conditions in the current territory and mating potential in the current territory. Male choices to emigrate were strongly related to cues that mating potential in the current territory was low, as predicted by the mate searching hypothesis. In Chapter 4, I examine how mixed singing in Wood Warblers affects their ability to co-occur with their locally more abundant sister species, the Western Bonelli’s Warbler (“Bonelli’s Warbler,” P. bonelli). It has been hypothesized that an increase in interspecific acoustic similarity (e.g., via mixed singing) might facilitate co-occurrence via either an increase in competitor recognition (promoting interspecific territoriality) or reduced aggression (due to enhanced neighbor recognition). Alternatively, it has also been suggested that interspecific asymmetries in aggression (which could result from an asymmetry in acoustic similarity) cause competitive exclusion of the less aggressive species. To determine which if any of these scenarios might be occurring between Wood and Bonelli’s Warblers, I conducted a song playback experiment, calculated levels of interspecific territory overlap and determined patterns of co-occurrence at the study site level. The results were not consistent with any of the hypotheses tested, suggesting that mixed singing in Wood Warblers neither helps nor hinders co-occurrence with Bonelli’s Warblers. By considering the multi-faceted nature of the social environment, this thesis brings together diverse topics for a more comprehensive understanding of social influences on the breeding behavior of migratory songbirds. The social environment of most species has and continues to be altered by human-induced global change. Thus, it remains an ongoing and important task to try to understand the behavioral, ecological and evolutionary consequences of these changes.

Understanding the impact of recreational disturbance caused by motor vehicles on waterbirds: a case study from the Bundala Wetland, Sri Lanka

Article

Full-text available

Apr 2022
J Coast Conservat

Promotion of recreational access is an important strategy that helps to impart conservation values to wetlands and aids in fostering sustainable employment for local communities who live in close proximity to wildlife habitats. Unregulated recreational vehicles in coastal wetlands can cause detrimental impacts on coastal avifauna. There is a dearth of information especially in the South Asian context on the impact of recreational disturbance to waterbirds that can inform the management of wetland destinations. This study examined the response of selected water birds to motor vehicles using multispecies experimental disturbance trials conducted at Bundala National Park, Sri Lanka; a Ramsar-listed wetland of global importance. The selected species had significantly different sensitivities to disturbance caused by motor vehicles (log-rank test, χ² = 51.7, P < 0.05). The probability of a bird responding to a moving vehicle parallel to the bird at a distance of 75 m was greater than 0.6 for all selected species (Calidris minuta, Charadrius alexandrinus, Himantopus himantopus, Limosa limosa, Platalea leucorodia and Mycteria leucocephala) except Hydroprogne caspia. Resting birds appeared to be more affected by recreational disturbance when compared to foraging birds. Larger birds (height of adult bird: 80-105 cm) were more sensitive to recreational stimuli, compared to smaller birds (10-20 cm). In general, responses of birds for recreational stimuli, were prominent up to 100 m from the source. Selected waterbirds showed longer response distances in habitats exposed to high vehicle traffic activity suggesting possible habituation of birds to recurring disturbance. Our findings suggest a minimal setback buffer of 100 m needs to be employed to manage recreational disturbance from motor vehicles at Bundala National Park.

Short Distance Movement Thesis

Thesis

Full-text available

Mar 2022

T. L Hillis

Woodland caribou, Rangifer tarandus caribou, are believed to employ a spatially segregated anti-predator strategy, distributing themselves in a manner that minimizes contact with primary predators, such as wolves, Canis lupus (Bergerud 1983, Bergerud and Page 1987). The success of this antipredator strategy may be negatively impacted by increased levels of disturbance. For example, linear corridors have been shown to affect survivorship of ungulates by increasing human access and hunting and/or by providing travel routes for wolves (James and Stuart-Smith 2000). Similarly, the increased habitat fragmentation caused by fire and logging may change the timing and movement activities of animals (Metsaranta 2002) and may influence the ability of caribou to locate suitable escape and/or forage sites (Rettie and Messier 1998, Smith et al. 2000). The primary purpose of this study was to assess the activity and short distance movement patterns of woodland caribou in home ranges impacted by different disturbance levels within the northwest region of Ontario. It was hypothesized that: (1) seasonal and annual changes in activity occur in woodland caribou in this region, (2) disturbance level affects the seasonal and annual activity patterns within home ranges, (3) seasonal and annual short distance movement patterns occur in woodland caribou in this region, and (4) disturbance level affects the seasonal and annual short distance movement patterns within home ranges.

The nuthatch and the hare: Slow explorers dominate in a re-established population of the Brown-headed Nuthatch (Sitta pusilla) two decades later

Article

Full-text available

Mar 2022

Animal behavior regularly has substantial effects on the outcomes of reintroduction efforts. Reintroduction involves capturing a subset of individuals from a source population and releasing them into novel environments where variation in retention rates, predation, and territory acquisition could affect the age-class structure, sex ratio, and genetic and phenotypic characteristics of restored populations. Exploratory behavior, quantified as the rate that individuals explore novel settings, is one such heritable trait that might be affected by translocation, especially given recent studies suggesting that exploratory behavior can predict the survival and retention of individuals in unfamiliar environments. To assess the potential effects that translocation may have on exploratory behavior, we compared exploratory behavior for three Brown-headed Nuthatch (Sitta pusilla) populations: (1) a population reintroduced to Everglades National Park in 1998; (2) a population close to the original source population, and (3) a distant control population in north Florida. Exploratory behavior was quantified by placing individuals (n=17 per population) in an exploratory chamber and comparing flights/hops, scanning events, thoroughness of exploration, and other movement behaviors. We found that individuals in the reintroduced population scanned less, conducted fewer flights/hops, and were more sedentary than individuals in the other populations. Our findings suggest a shift in the prevalence of personality types toward slow explorers has taken place in the 20 years since reintroduction, adding to other studies suggesting that slow explorers fare better in novel environments. Although the reintroduced population contained fewer fast-exploring individuals relative to the other populations studied, fast-explorer phenotypes may increase over time if they convey the fitness benefits described in other studies.

Cumulative Effects of Habitat Change: American Marten Habitat Selection and 30 Years of Forest Harvesting in Maine

Article

Dec 2021

Tyler Woollard

Wildlife habitat conservation in landscapes where human activities cause chronic habitat disturbance is contingent upon developing land management strategies that minimize the effects of future habitat changes on wildlife populations. Long term studies can provide unique opportunities to understand how species respond to progressive habitat change, and such an understanding can reveal ways in which the often conflicting objectives of wildlife habitat conservation and human land use can be reconciled. Characterizing how animals respond behaviorally to habitat conditions may be a useful tool for identifying potential negative effects of disturbance before such effects impact rates of species occurrence, population demography, or other metrics indicative of population viability. The composition and configuration of Maine’s forests have been progressively and drastically altered by forest harvesting, and behavioral responses displayed by forest-associated species to the temporally cumulative effects of forest harvesting can inform forest management strategies for the conservation of Maine’s forest-associated wildlife. I evaluated the effects of forest composition and patch configuration on patterns of patch-scale habitat selection displayed by American marten (Martes americana) to identify marten responses to the cumulative and multidimensional effects of forest harvesting across a 30-year period (1989-2019). I used a spatially-explicit time series of forest harvesting and forest inventory data to classify forest types that were ecologically distinct to marten and were easily interpretable from a forest management perspective. I coupled marten habitat maps with a telemetry dataset collected from resident, non-juvenile marten to estimate patterns of marten habitat selection as they related to forest height and harvest history, the availability of different forest types within marten home ranges, and forest patch configuration using resource selection functions within an information-theoretic framework. Tall well-stocked forests (TWF) >12m in height, whether mature, uncut forest or originating from previously clearcut forest, received similar selection, and selection by marten for TWF increased relative to other forest types as TWF availability decreased as a result of forest harvesting. Decreased TWF availability within marten home ranges was also associated with an increase in the relative preference marten displayed for less isolated and smaller patches of TWF. The negative effect of patch area suggests that marten increasingly utilized all available TWF patches, regardless of patch size, as this forest type became less abundant. These results indicate that marten require extensive use of TWF, which is limited when forest harvesting results in a scarcity of sparsely distributed TWF patches, and that regenerating clearcuts regain the structural characteristics selected by marten when trees reach 12m. Relative avoidance of scrub and early-successional clearcuts (height) was stronger among marten occupying home ranges where these forest types were abundant, indicating a risk or cost associated with individuals increasing their use of early-successional forest in proportion to increased availability. Partial harvests and mid-successional forest types (9m-12m tree height) received similar selection as well as extensive use by marten. These forest types were preferred relative to unforested areas, forested road edges, and scrub and early-successional clearcuts, suggesting that some harvested forest types constitute a hospitable matrix for marten. Marten responses in selection to the shape and area of hospitable matrix patches were consistent with marten use of hospitable matrix being primarily associated with movement between TWF patches, which indicates that marten selection of partial harvests and mid-successional forest is dependent on the selection of adjacent TWF patches. Patterns of marten habitat selection I documented suggest that the effects of forest harvesting on marten may be reduced if harvests are 1) positioned adjacent to multiple TWF patches, 2) do not separate TWF patches by more than 300m, and 3) are located within female marten home range sized areas (~2.5km2) with high proportions of TWF relative to the surrounding landscape. Small patches of TWF within occupied areas should not be preferentially harvested unless they are highly isolated, especially in areas with low relative TWF abundance. Additionally, minimizing road construction within areas occupied by marten, decommissioning established roads wherever future access is not an immediate management priority, and reducing the intensity of road edge maintenance will diminish the impacts of logging roads on marten. This research illustrates how animal location data collected across periods of habitat change can be used to precisely characterize species’ responses to the interrelated components of that change. Further, this study demonstrates how the components of habitat change can be quantified in ecologically meaningful ways that are also easily interpretable from a land management perspective, ensuring the translatability of results to readily implementable recommendations for habitat conservation.

Habitat selection of the arboreal marsupial Dromiciops gliroides and potential effects on the seed dispersal of the mistletoe Tristerix corymbosus

Article

May 2024

Habitat selection of seed-dispersing animals influences where seeds are deposited, seedling establishment, and population dynamics. In the Patagonian temperate forests there is a key mutualistic relationship between the mistletoe Tristerix corymbosus and its seed disperser, the nocturnal arboreal marsupial Dromiciops gliroides. In this study, we analyzed the habitat selection of D. gliroides at two different habitat scales: site selection and step selection. Also, we analyzed if the selected microsites by this marsupial are suitable for the establishment of T. corymbosus. We captured 24 individuals in Parque Municipal Llao Llao (San Carlos de Bariloche, Argentina) during the austral summer of 2014 and 2015. The captured individuals were equipped with a spool and line device to register habitat use: substrate, vegetation cover, diameter and angle of branches. We used a conditional hierarchical logistic Bayesian regression at each habitat scale. We found that, at the site scale, D. gliroides selected habitats with more shrub cover and, at the step scale, D. gliroides selected more T. corymbosus host species. Besides, our results show that D. gliroides selected branches with intermediated size (4–10 cm) and also horizontal branches. The relationship between the selected sites and those where it deposits the T. corymbosus seeds suggests that the marsupial dispersing the seeds to suitable hosts and branch sizes. Therefore, the behavior of D. gliroides would be favoring the regeneration of T. corymbosus.

Mustelidae Navigation

Chapter

Full-text available

May 2022

上海市城市化梯度上饰纹姬蛙警戒距离的变化

Article

Mar 2024

Evaluating bottom-up forcing of a rocky intertidal resource harvest on a high trophic-level consumer group

Article

Mar 2024
ESTUAR COAST SHELF S

A multi‐property assessment of intensity of use provides a functional understanding of animal movement

Article

Dec 2023
Methods Ecol. Evol.

The intensity of use of a location is one of the most studied properties of animal movement, yet movement analyses generally focus on the overall use of a location without much consideration of how patterns in intensity of use emerge. Extracting properties related to intensity of use, such as the number of visits, the average and variation in time spent and the average and variation in time between visits, could help provide a more mechanistic understanding of how animals use landscape. Combining and synthesizing these properties into a single spatial representation could inform the role that a location plays for an animal. We developed an R package named ‘UseScape’ that allows the extraction of these metrics and then clustered them using mixture modelling to create a spatial representation of the type of use an animal makes of the landscape. We illustrate applications of the approach using datasets of animal movement from four taxa and highlight species‐specific and cross‐species insights. Our framework highlights properties that functionally differ in how animals use them, contrasting, for example, heavily used locations that emerge because they are frequented for long durations, locations that are repeatedly and regularly visited for shorter durations of time or locations visited irregularly. We found that species generally had similar types of use, such as typical low, mid and high use, but there were also species‐specific clusters that would have been ignored when only focusing on the overall intensity of use. Our multi‐system comparison highlighted how the framework provided novel insights that would not have been directly obtainable by currently available approaches. By making the framework available as an R package, these analyses can be easily applicable to a myriad of systems where relocation data are available. Movement ecology as a field can strongly benefit from approaches that not just describe patterns in space use, but also highlight the behavioural mechanisms leading to these emerging patterns.

Unravelling arthropod movement in natural landscapes: small-scale effects of body size and weather conditions

Preprint

Full-text available

Sep 2023

Arthropod movement has been noticeably understudied compared to vertebrates. A crucial knowledge gap pertains to the factors influencing arthropod movement at habitat boundaries, which has direct implications for population dynamics and gene flow. While larger arthropod species generally achieve greater dispersal distances and large-scale movements are affected by weather conditions, the applicability of these relationships at a local scale remains uncertain. Existing studies on this subject are not only scarce but often limited to a few specific species or laboratory conditions. To address this knowledge gap, we conducted a field study in two nature reserves in Belgium, focusing on both flying and cursorial arthropods. Over 200 different arthropod species were captured and released within a circular setup placed in a resource-poor environment, allowing quantification of movement speed and direction. By analysing the relationship between these movement variables and morphological (body size) as well as environmental factors (temperature and wind), we aimed to gain insights into the mechanisms driving arthropod movement at natural habitat boundaries. For flying species, movement speed was positively correlated with both body size and (tail)wind speed. In contrast, movement speed of cursorial individuals was solely positively related with temperature. Notably, movement direction was biased towards the vegetated areas where the arthropods were originally caught, suggesting an internal drive to move towards suitable habitat. This tendency was particularly strong in larger flying individuals and under tailwind conditions. Furthermore, both flying and cursorial taxa were hindered from moving towards the habitat by strong upwind. In conclusion, movement speed and direction at patch boundaries are dependent on body size and prevailing wind conditions, and reflect an active decision-making process.

American Bison (Bison bison) - A Rangeland Wildlife Continuum

Chapter

Full-text available

Sep 2023

American bison (Bison bison) are the largest extant land animal in North America and have an important history and contemporary role in modern conserva-tion. Bison historically had the widest continental distribution of all native ungulates but now only function as wildlife under natural selection on < 1.2% of the original range. Bison as rangeland wildlife occur on an array of exclusive and overlapping governance jurisdictions (e.g., Federal, State, Provincial, County, and Tribes and First Nations), private not-for-profit conservation lands enterprises, zoo and educa-tion enterprises, and for-profit commodity production. The historical and prevailing relationships within and between these higher order sectors are very complex and often conflicting, yet each sector has invested tremendous effort and public and private resources to increase the total abundance of bison to present levels. Despite long-term public investment in wild bison conservation, the private sector has far out-stripped wild bison, resulting in a potentially divergent evolution trajectory towards species domestication. The primary ecosystem function of plains bison on range-lands is contributing to plant community heterogeneity through patchily distributed grazing events that create mosaics of grazing pressure. Additionally, bison exhibit a myriad of other roles in their environment through direct and indirect interactions. Perhaps more than with other rangeland wildlife species, genetics play an outsized role in current bison population management given historical bottlenecks and inten-tional cross breeding of bison and cattle. However, moving forward the interplay between population size, isolation, and genetic diversity is more important. Along the continuum of bison management there exist a wide variety of rangeland manage-ment techniques. However, as a wildlife species, the rangeland management practices associated with bison have generally focused on disturbance ecology with a more recent push to understand the impacts of bison grazing at scale. The question of scale is important given that every bison is behind a barrier, thus restricting their impacts on rangeland ecology and processes. Bison and cattle are considered by many to be potential competitors, due to large overlaps in diet and body size, and much research has focused on the ecological equivalence of the two species. While this is still not without controversy, bison and cattle are not incompatible when properly managed. Chronic infection of wild bison populations with diseases that can be transmitted to livestock and humans is an important factor affecting potential recovery of bison outside existing reserve boundaries. Climate change may represent the next major challenge to bison, as it is expected to directly affect bison through decreased forage and water availability and increased thermal stress. These threats, combined with the differences in bison management practices between sectors have led some to classify bison as moderately vulnerable to climate change, recommending the creation of a ‘bison coalition’ that could seek climate change adaptation solutions through shared stewardship. While much of the continental historical range is no longer available for bison restoration, there are exciting conservation opportunities that are finding voice through the vision of “Shared Stewardship” that embraces innovative collaboration to work together across jurisdictions and sectors to successfully address the scale, complexity, and ecological and cultural significance of wild bison.

Scale-dependent habitat selection is shaped by landscape context in dispersing white-tailed deer

Preprint

Full-text available

Aug 2023

Context. Identifying how animals select habitat while navigating landscapes is important for understanding behavioral ecology and guiding management and conservation decisions. However, habitat selection may be spatially and temporally plastic, making it challenging to quantify how species use resources across space and time. Objectives. We investigated how landscape context and dispersal shape habitat selection at multiple spatial scales in white-tailed deer (Odocoileus virginianus). Methods. Using step-selection functions, we quantified habitat selection of landcover and topographic covariates at three spatial scales for juvenile males during three movement periods (before, during, after dispersal) in two regions of Missouri, USA — a fragmented, low forest cover region with rolling hills, and a forested, topographically variable region. Results. Although selection for forest cover increased after dispersal in both regions, deer selected forest cover at smaller spatial scales in the fragmented, low forest cover region. This result indicates scale of selection was dependent on forest availability and configuration with deer likely perceiving landscapes differently across their distribution. Functional responses to topography differed in magnitude and direction between regions with deer avoiding roads and selecting valleys in the rolling hills region (especially during dispersal) while showing no response to roads and selecting for ridgelines (during dispersal) in the topographically variable region. This result suggests movement behavior is strongly dependent on topography. Conclusions. Although deer may select habitats similarly among regions, landscape context and movement period shape the scale, strength, and direction of selection. This result has important implications for how deer use landscapes across different regional contexts.

Identifying signals of memory from observations of animal movements

Preprint

Full-text available

Aug 2023

Incorporating memory (i.e., some notion of familiarity or experience with the landscape) into models of animal movement is a rising challenge in the field of movement ecology. The recent proliferation of new methods offers new opportunities to understand how memory influences movement. However, there are no clear guidelines for practitioners wishing to parameterize the effects of memory on moving animals. We review approaches for incorporating memory into Step-Selection Analyses (SSAs), a frequently used movement modeling framework. Memory-informed SSAs can be constructed by including spatial-temporal covariates (or maps) that define some aspect of familiarity (e.g., whether, how often, or how long ago the animal visited different spatial locations) derived from long-term telemetry data. We demonstrate how various familiarity covariates can be included in SSAs using a series of coded examples in which we fit models to wildlife tracking data from a wide range of taxa. We discuss how these different approaches can be used to address questions related to whether and how animals use information from past experiences to inform their future movements. We also highlight challenges and decisions that the user must make when applying these methods to their tracking data. By reviewing different approaches and providing code templates for their implementation, we hope to inspire practitioners to investigate further the importance of memory in animal movements using wildlife tracking data.

Getting lost in the matrix? On how the characteristics and arrangement of linear landscape elements influence ecological connectivity

Article

Full-text available

Aug 2022
LANDSCAPE ECOL

Context Linear landscape elements (LLEs) such as ditches and hedgerows can increase the ecological connectivity of habitat embedded within agricultural areas by acting as corridors for animal movement. However, we lack knowledge on how the spatial arrangement of LLEs influence dispersal, impeding our ability to offer robust advice on how best to add new LLEs to improve connectivity. Objectives To examine how the width and spatial orientations of LLEs composing an intersecting network might influence connectivity across landscapes. Methods We used an individual-based dispersal model to simulate the stochastic movement of small organisms through stylised LLEs of different characteristics. Landscapes were composed of two habitat patches separated by a grid-like network of LLEs composed of two types: (1) connecting-edges (touching patches on either end) and (2) transecting-edges (running perpendicular to connecting-edges). By altering numbers and widths of each LLE type we sought to understand the effect of these variables on inter-patch dispersal rates. Results Increasing the number or width of connecting-edges improved connectivity but, conversely, increasing numbers or widths of transecting-edges reduced it. The greater freedom of movement offered by increasing numbers of transecting-edges may have inhibited connectivity, as individuals with limited perceptual-range were more likely to become trapped in complex networks and thus fail to navigate to suitable habitat patches. Conclusions Orientation of LLEs with respect to landscape resources greatly affects their impact on connectivity. The addition of LLEs to landscapes may decrease their connectivity for small, flightless species if they do not directly channel dispersers toward landscape resources.

Principles and Methods in Landscape Ecology: An Agenda for the Second Millennium

Chapter

May 2022

Almo Farina

Landscape ecology has a long history in scientific research and humanities with an epistemology rich in different interpretations and meanings that often produces not coincident syntheses. A landscape can be considered a domain, a system, or a unit. Apparently heterogeneous and fragmented, the land mosaic literally connects not only environmental patches of different composition, morphology, and functions but reunifies distant disciplines and theoretical perspectives.

Movement and behavior of the sand dollar Mellita tenuis (Echinodermata: Echinoidea)

Article

Feb 2022

Mellita tenuis occurs in large aggregations in the eastern Gulf of Mexico, and are. major bioturbators of sandy environments. In this laboratory study, M. tenuis were placed in a laboratory enclosure under varying treatments (Time of Day, Size, Predatory Cues, Feeding History, Density), and video recorded for 3–4 hr. Five variables were analyzed: time in forward plus rotational movement (Movement), time in forward movement alone (Progression), time covered by sand (Covered), distance moved (Distance), and how fast they moved (Speed). There was no diel rhythm pattern found for any of the variables studied amongst Time of Day treatments. Large individuals covered less often, moving further and nearly two times faster than small individuals. Neither Feeding History nor Predatory Cues had an effect. Lower density aggregations spent more time in Movement and Progression. Both larger and smaller individuals contribute to bioturbation activitiespotentially impacting the habitat across 24 hr.

The role of corridors in conservation: What do we know and where do we go?

Chapter

Full-text available

May 1991

Communities in a Landscape: The Influence of Habitat Heterogeneity on the Interactions between Species

Article

Full-text available

Nov 1991

Brent J Danielson

A model similar to the single-species source-sink models developed by Pulliam and by Pulliam and Danielson is described for species that have "distinct" habitat preferences and preemptive occupation of sites within habitats. The model shows that the interactions between two species do not result solely from the intrinsic properties of the species involved. They are also functions of the landscape in which the species occur. One species may cause an increase (facilitation) in the equilibrium population size of another species if the high-quality source habitat for the second species is rare relative to the abundance of low-quality sink habitat. A species may inhibit another if the second species' source habitat is abundant. Combinations of facilitation and inhibition effects describe the interactions between two species. There are two sets of possible interactions for any landscape of two habitat types. These are [(-, +), (-, -), (+, -)} and {(-, +), (+, +), (+, -)}. Species for which individuals can sample a large number of sites are likely to exhibit one of the interactions in the first set. Species for which individuals sample only a few sites are likely to exhibit interactions from the second. Within each set of interactions, the relative abundances of each habitat will determine which interaction will occur in the landscape.

The Effects of Edge Permeability and Habitat Geometry on Emigration from Patches of Habitat

Article

Full-text available

Apr 1987

Edge permeability, phi, reflects the tendency of a disperser reaching the edge of a habitat patch to cross the boundary and emigrate; edge permeability is positively related to emigration for any given habitat patch. The edge-to-size ratio (ESR), its the proportion of home ranges at the edge of a habitat patch; for any degree of edge permeability greater than zero, the ESR is positively related to emigration. When habitats have relatively hard edges (e.g., 0 = or < phi = or < 0.1), edge permeability is a more important determinant of emigration than is the ESR. When habitats have relatively soft edges (phi > 0.1), the ESR is the more important determinant. -from Authors

An artificial intelligence modelling approach to simulating animal/habitat interactions

Article

Full-text available

Dec 1988
ECOL MODEL

Saarenmaa, H., Stone, N.D., Folse, L.J., Packard, J.M., Grant, W.E., Makela, M.E. and Coulson, R.N., 1988. An artificial intelligence modelling approach to simulating animal/habitat interactions. Ecol. Modelling, 44: 125-141. Ecological modellers have begun to recognize the potential of object-oriented program- ming techniques in structuring models. However, little has been done to take advantage of artificial intelligence's (AI) symbolic representations to model the decision-making processes of animals. Here, a generic model of animal-habitat interaction and a specific model of moose-, Alces alces L., forest interactions in Finland are described that are event-driven and behavior-based. Individual level simulation is accomplished through an object-oriented knowledge representation scheme and AI techniques to implement a hierarchical decision- making model of behavior. The habitat is likewise represented in an object-oriented scheme, allowing the simulation of a heterogeneous environment. Other AI techniques for modelling behavior, memory, and actions are discussed including LISP methods, rule-based reasoning, and several search algorithms. Simulations of the moose-forest system show the power of this approach but are not intended to advance the theory of large-herbivore behavior and foraging. AI techniques are found to be most beneficial in (a) studying population processes based on individual level models of behavior, (b) modelling spatial heterogeneity, (c) building event-driven models, (d) providing a conceptual clarity to model construction, and (e) providing a structure equally well suited to simulating resource management.

Ecological Processes That Affect Populations in Complex Landscapes

Article

Full-text available

Oct 1992

We describe a general framework for understanding the ecological processes that operate at landscape scales. The composition of habitat types in a landscape and the physiognomic or spatial arrangement of those habitats are the two essential features that are required to describe any landscape. As such, these two features affect four basic ecological processes that can influence population dynamics or community structure. The first two of these processes, landscape complementation and landscape supplementation, occur when individuals move between patches in the landscape to make use of non-substitutable and substitutable resources, respectively. The third process, source-sink dynamics, describes the consequences of having different individuals in the same population occupy habitat patches of different qualities. The fourth process, the neighborhood effect, describes how landscape effects can be amplified when the critical resources are in the landscape immediately surrounding a given patch. Definition of these landscape features and general processes will allow a better synthesis of how landscape variation affects populations and communities.

Ecological Mechanisms and Landscape Ecology

Article

Full-text available

Apr 1993
OIKOS

Landscape ecology deals with the effects of the spatial configuration of mosaics on a wide variety of ecological phenomena. Because problems in many areas of conservation biology and resource management are related to landscape use, development of a rigorous theoretical and empirical foundation for landscape ecology is essential. We present an approach to research that focuses on how individual-level mechanisms operating in a heterogeneous mosaic produce ecological patterns that are spatially dependent. The theoretical framework that we develop considers the density and distribution of a population among patches as a function of (a) within-patch movement patterns of individuals; (b) emigration from patches as a function of population density, patch configuration, patch context, and within-patch movement; and (c) loss of individuals as they disperse through landscape elements. This theoretical framework is coupled with an empirical approach that emphasizes the use of experimental model systems (EMS), sm

Fractal Patterns of Insect Movement in Microlandscape Mosaics

Article

Full-text available

Mar 1995

How individuals move, whether in short-term searching behavior or long-term dispersal influences the probability that individuals will experience physiological stress or encounter appropriate habitat, potential mates, prey, or predators. Because of variety and complexity, it is often difficult to make sense of movements. Because the fractal dimension of a movement pathway is scale independent, however, it may provide a useful measure for comparing dissimilar taxa. The authors use fractal measures to compare the movement pathways of individual beetles occupying semiarid shortgrass steppe in north-central Colorado. 20 refs., 1 fig., 1 tab.

Animal Movements and Population-Dynamics in Heterogeneous Landscapes

Article

Full-text available

Mar 1992

Organisms respond to environmental heterogeneity at different scales and in different ways. These differences are consequences of how the movement characteristics of animals - their movement rates, directionality, turning frequencies, and turning angles - interact with patch and boundary features in landscape mosaics. The interactions of movement patterns with landscape features in turn produce spatial patterns in individual space-use, population dynamics and dispersion, gene flow, and the redistribution of nutrients and other materials. We describe several theoretical approaches for modeling the diffusion, foraging behavior, and population dynamics of animals in heterogeneous landscapes, including: (1) scaling relationships derived from percolation theory and fractal geometry, (2) extensions of traditional patch-based metapopulation models, and (3) individual-based, spatially explicit models governed by local rules. We conclude by emphasizing the need to couple theoretical models with empirical studie

Spatially Explicit Population Models: Current Forms and Future Uses

Article

Full-text available

Feb 1995

Spatially explicit population models are becoming increasingly useful tools for population ecologists, conservation biologists, and land managers. Models are spatially explicit when they combine a population simulator with a landscape map that describes the spatial distribution of landscape features. With this map, the locations of habitat patches, individuals, and other items of interest are explicitly incorporated into the model, and the effect of changing landscape features on population dynamics can be studied. In this paper we describe the structure of some spatially explicit models under development and provide examples of current and future research using these models. Spatially explicit models are important tools for investigating scale-related questions in population ecology, especially the response of organisms to habitat change occurring at a variety of spatial and temporal scales. Simulation models that incorporate real-world landscapes, as portrayed by landscape maps created with geographi

Behavioural constraints and conservation biology: Conspecific attraction and recruitment

Article

Full-text available

Jul 1993
TRENDS ECOL EVOL

Wildlife managers have devoted considerable time and research to determine how animals judge the suitability and quality of their habitat. These analyses typically center on habitat characteristics and often produce equivocal results. An additional method of habitat assessment is to examine the extent to which animals, and particularly birds, use conspecifics as cues to establishing breeding and feeding territories. Conspecifics can be indicators of habitat quality, or they might intrinsically affect reproductive success. Here we discuss the implications of conspecific attraction for biologists who wish to conserve endangered species that are living in fragmented habitats.

Regional Forest Fragmentation and the Nesting Success of Migratory Birds

Article

Full-text available

Apr 1995

Forest fragmentation, the disruption in the continuity of forest habitat, is hypothesized to be a major cause of population decline for some species of forest birds because fragmentation reduces nesting (reproductive) success. Nest predation and parasitism by cowbirds increased with forest fragmentation in nine midwestern (United States) landscapes that varied from 6 to 95 percent forest cover within a 10-kilometer radius of the study areas. Observed reproductive rates were low enough for some species in the most fragmented landscapes to suggest that their populations are sinks that depend for perpetuation on immigration from reproductive source populations in landscapes with more extensive forest cover. Conservation strategies should consider preservation and restoration of large, unfragmented "core" areas in each region.

The theory of wildlife corridor capability

Article

Jan 1991

Decisions about the identity of the species for which the corridor is designed must be made early in the analysis. Corridor capability analysis depends on a thorough grasp of the life history and demography of the candidate species. The potential benefits of corridors for specific species must be weighed against the potential detrimental effects for the ecosystems as wholes. A computer simulation of corridor capability for animals suggested: 1) optimum corridor width depends on the strength of the edge effect - the higher the relative mortality rate of the edge, the wider the corridor must be; 2) any departures from linearity, even for relatively intelligent animals, may be deleterious; and 3) the shape of corridors may be important. -from Authors

Corridors and connectivity: animal populations in heterogeneous environments

Article

Jan 1991

G. Merriam

At the landscape scale, the degree of linkage within and between metapopulations can be represented conceptually as connectivity. Landscape patterns can constrain connectivity; barriers and isolating habitats can bound metapopulations and genetic breeding units. Habitat patches change in time, by human impact, land use changes, crop rotation, succession and catastrophes. Animals must move through the landscape to match their changing resource needs to the changing distribution of resources in the landscape. Frequency of extinctions in patches and rates of recolonization of these patches can be related to connectivity. Effects of corridor quality can be simulated by computer models, as can effects of patch quality and of patch and corridor arrangements. In addition to demographic effects, these interactions between connectivity and frequency of local extinctions can have important effects on the genetics of patchy populations. Management plans can be built on an understanding of the dynamics of patchy populations and their resources. -from Author

Competition for resources

Chapter

Jan 1991

Simulating Winter Interactions Among Ungulates, Vegetation, and Fire in Northern Yellowstone Park

Article

Aug 1994

The interaction of large-scale fire, vegetation, and ungulates is an important management issue in Yellowstone National Park. A spatially explicit individual-based simulation model was developed to explore the effects of fire scale and pattern on the winter foraging dynamics and survival of free-ranging elk (Cervus elaphus) and bison (Bison bison) in northern Yellowstone National Park. The Northern Yellowstone Park (NOYELP) model simulates the search, movement, and foraging activities of individuals or small groups of elk and bison. The 77 020-ha landscape is represented as a gridded irregular polygon with a spatial resolution of 1 ha. Forage intake is a function of an animal's initial body mass, the absolute amount of forage available on a site, and the depth and density of snow. When the energy expenditures of an animal exceed the energy gained during a day, the animal's endogenous reserves are reduced to offset the deficits. Simulations are conducted with a 1-d time step for a duration of 180 d, [approximately]1 November through the end of April. Simulated elk survival for three winters (1987-1988; 1988-1989; 1990-1991) agreed with observed data.

Conspecific Attraction and the Determination of Metapopulation Colonization Rates

Article

Sep 1990
CONSERV BIOL

Host-plant finding for oviposition by adult cabbage root fly, Delia radicum

Article

Dec 1988
J INSECT PHYSIOL

Stephen Nottingham

Host-plant finding by female cabbage root fly, Delia radicum, begins once they have mated and become gravid. Host-plant odour detected downwind of plants induces an upwind anemotactic response, involving both mechano-orientation and take-off into the odour-laden wind from a fixed substrate and optomotor anemotaxis while in flight. The behavioural mechanisms involved in odour source location in D. radicum are broadly similar to other Diptera locating host-plant odours and to Lepidoptera locating pheromone sources. D. radicum integrates olfaction with other sensory modalities as a host-plant is approached, with vision becoming important within the vicinity of the plant. On arrival at the host-plant, chemo-reception and mechano-reception are used in host-plant acceptance, oviposition stimulation and the choice of an oviposition site. The host-plant finding behaviour culminating in oviposition could potentially be modified at any stage for pest control purposes.

Translating Foraging Movements in Heterogeneous Environments into the Spatial Distribution of Foragers

Article

Aug 1991

P. Turchin

Uses data on movement tracks of Euphydryas anicia females to calculate butterfly residence indices in host-plant patches vs. nonhost environment. The predicted distribution of butterflies among host and nonhost areas differed by only 16% from the actual distribution, as documented by an independent data set. The model was also applied to data from 3 studies on insect movement and spatial distribution. -from Author

Population Dynamics in Spatially Complex Environments: Theory and Data: Discussion

Article

Nov 1990
PHILOS T R SOC B

Population dynamics and species interactions are spread out in space. This might seem like a trivial observation, but it has potentially important consequences. In particular, mathematical models show that the dynamics of populations can be altered fundamentally simply because organisms interact and disperse rather than being confined to one position for their entire lives. Models that deal with dispersal and spatially distributed populations are extraordinarily varied, partly because they employ three distinct characterizations of space: as \`islands' (or \`metapopulations'), as `stepping-stones', or as a continuum. Moreover, there are several different ways of representing dispersal in spatially structured environments, as well as several possibilities for allowing environmental variation to come into play. In spite of this variety, a few common themes emerge from spatial models. First, island and stepping-stone models emphasize that little can be concluded from simply recording patterns of occupancy, instead a metapopulation's fate will be determined by the balance between local extinction and recolonization and how that balance interacts with random catastrophes. Island and stepping-stone models also make it clear that the spatial dimension, in particular spatial subdivision, can alter the stability of species interactions and opportunities for coexistence in both predator-prey and competitive systems. Continuum models, which usually take the form of reaction-diffusion equations, address slightly different questions. Reaction-diffusion theory suggests that in uniform environments, certain combinations of local dynamics and dispersal can produce persistent irregularities in the dispersion of species. These striking spatial patterns, which are called diffusive instabilities, can arise from predator-prey interactions, Lotka-Volterra competitive interactions, and from density-dependent population growth in an age-structured population. Moreover, although they differ fundamentally in their structure, the three major classes of spatial models share the common generalization that spatial effects should be expected only for: (i) selected spatial scales; (ii) specific dispersal rates, and (iii) particular patterns of environmental variation relative to the frequency and range of dispersal. The theoretical possibilities are thus contingent on spatial scale and dispersal rates. Although explicit experimental tests of spatial models are non-existent, a handful of studies report general changes in species interactions associated with manipulations of habitat subdivision. Observational studies with adequate data concerning dispersal and scale are also scarce; but those few observational studies with the appropriate supporting information consistently show profound spatial effects, especially effects due to habitat subdivision. The challenge for empiricists is to investigate more rigorously the roles of spatial subdivision and dispersal in natural communities. The challenge for theoreticians is to make the empiricist's job easier; this can best be done by delineating when spatial effects are most likely to be influential, and by offering guidance on how to design appropriate experiments. Simply saying that the spatial environment is important is to mouth a platitude: what we need to know is whether this presumed importance amounts to much in natural systems.

A general model of populations in patchy habitats

Article

Jul 1988
APPL MATH COMPUT

Lenore Fahrig

A general model is proposed for study of the effects of the spatial arrangement of habitat patches on population dynamics of resident populations. Previously proposed models are shown to be inadequate or undesirable for the detection of such effects. The proposed model is a stochastic discrete-time simulation model, in which within-patch processes are modeled using a discrete approximation to the logistic equation. The explicit spatial arrangement of patches is included, and the exchange of organisms via interpatch dispersal depends on three sets of parameters: (i) the fraction of organisms which disperse from each patch, (ii) the distance which organisms disperse, and (iii) the distance from which dispersers can detect new patches. A set of simulation experiments was performed, to study the effects of the detection distance [parameter (iii) above] on the effect of the spatial arrangement of habitat patches on population dynamics. It was found that for low and high detection distances patch spatial arrangement is relatively unimportant. However, for intermediate detection distances the spatial arrangement has an important impact on population dynamics.

Population Dynamics in Complex Landscapes: A Case Study

Article

May 1992

Spatially explicit simulation models provide a powerful method for modelling landscape and population changes at large spatial scales and may prove useful as a management tool for mobile animal populations. As an example of this approach, the authors present a model designed to elucidate the effects of landscape-level variation in habitat dispersion on the size and extinction probability of avian populations in a region managed for timber production. In the model, habitat suitability and availability within the landscape change annually as a function of timber harvest and management strategies. The model incorporates life history characteristics of Bachman's sparrow Aimophila aestivalis, a species of management concern in the SE USA, and the landscape characteristics of the Savannah River Site, South Carolina, an area managed for timber production where the sparrow is relatively common. Life history characteristics used in the model include dispersal, survivorship, and reproductive success information reported for Bachmann's sparrow. Variation in demographic variables affect population size more than variation in dispersal ability. Changes in adult and juvenile survivorship have especially large impacts on the probability of population extinction. The presence of habitat types that serve as permanent sources of dispersers increases the total population size in the landscape, and lowers the probability of extinction. -from Authors

Water-finding in adult turtles: Random search or oriented behaviour?

Article

Apr 1995

S. Rebecca Yeomans

Tested whether adult yellow-bellied pond slider turtles have a water-finding ability that allows orientation to aquatic habitats in unfamiliar areas. 110 turtles were trapped and moved beyond their home range to an unfamiliar terrestrial habitat which had a single source of standing water nearby. After an acclimatization period, the turtles were released approximately 300 meters from the water's edge and out of sight of the water. After 1 hr, a heading for each turtle was calculated. Under overcast conditions orientation was random. Under clear conditions, released turtles oriented non-randomly and in the direction of the nearest water. Turtles with the ability to move to another aquatic habitat in a direct, efficient manner should have a selective advantage because reduced exposure to predators, reduced water stress, and reduced time away from feeding would lower the cost of overland travel. (PsycINFO Database Record (c) 2012 APA, all rights reserved)

Migration, Metapopulation Dynamics and Fugitive Co-existence

Article

Aug 1993
J THEOR BIOL

Many conclusions about migration in promoting persistence of metapopulations are based on very simple models, which ignore the effect of migration on local dynamics. These models are called patch models. Migration has typically several costs, including mortality of migrants en route, mortality owing to failure to establish a new population in an empty patch and, as costly migration decreases local population sizes, increased risk of extinction of local populations. We analyse metapopulation dynamics of single species and asymmetric competitors with models in which the equilibrium size of local populations is affected both by local processes and by migration. Our results clarify previous conclusions based on the simplified patch models which, when interpreted rigorously, deal with colonization, not migration. Our results predict that species with an intermediate rate of migration are the ones which tolerate best habitat fragmentation. The general conclusion from these models is that 'too much' migration can be as bad for metapopulation persistence as 'too little' migration.

The element of connectivity where corridor quality is variable

Article

Jul 1990

Small mammals in heterogeneous environments have been found to disperse along corridors connecting habitat patches. Corridors may have different survivability values depending on their size and the degree of cover they provide.This deterministic model tests the effects of varying corridor quality on the demographics of a metapopulation of Peromyscus leucopus. Two types of corridors are defined based on the probability of survival during a dispersal event.Results indicate that mortality during movement through corridors influences metapopulation demographics. We found that:1. Any connection between two isolated patches is better than no connection at all in terms of persistence and population size at equilibrium. 2. Metapopulations with exclusively high quality corridors between patches have a larger population size at equilibrium than do those with one or more low quality corridors. 3. Increasing the number of high quality corridors between patches has a positive effect on the size of the metapopulation while increasing the number of low quality corridors has a negative effect. 4. The addition to a metapopulation of a patch connected by low quality corridors has a negative effect on the metapopulation size. This suggest the need for caution in planning corridors in a managed landscape. 5. There is no relationship between the number of corridors and the metapopulation size at equilibrium when the number of connected patches is held constant. 6. Geometrically isolated patches connected by low quality corridors are most vulnerable to local extinctions. We conclude that corridor quality is an important element of connectivity. It contributes substantially to the effects of fragmentation and should be carefully considered by landscape planners.

Ranging strategies

Article

Feb 1989

David Dusenbery

Ranging is an initial phase of search behavior during which the organism conducting the search has no cues leading to a specific target. Various strategies for conducting this phase of search are considered. Classical search theory developed for searching for ships at sea is described. The concept of a cross section for detection is developed. A random walk model is introduced, which more appropriately describes the behavior of some organisms, and relatively recent relations for the mean time to capture in molecular diffusion are incorporated. The analysis demonstrates that the distance between targets has a stronger influence on success than does the range of detection. In addition, quantitative comparison of the efficiency of a straight search path to a random walk is obtained. The relative disadvantage of the random walk is nearly proportional to the ratio of the step size to the range of detection for both 2 and 3 dimensional searches. This result demonstrates the importance of collimating stimuli that enable an organism to maintain a straight course while ranging.

Spatial Scale Mediates the Influence of Habitat Fragmentation

Article

Jun 1992

Increasingly, conservationists are seeking insights from ecological theory to choose strategies of habitat management that will best maintain threatened species. Often, these questions revolve around ways of mitigating the dangers posed by habitat fragmentation. Problems involving the scale of both animal movement and spatial heterogeneity inexorably arise when assessing the effects of fragmentation. We present results from a simple spatial model that simulates the dispersal of animals in a landscape of stochastically clustered habitat fragments. Varying the number of clusters and the spatial scale at which clustering occurs illustrates that heterogeneity has different and conflicting effects on animal movement when it occurs at different scales. Indeed, the scale of clustering is the most important feature in determining disperser performance in our model. Seeking to compare our modeling results with actual data, we review empirical studies of fragmented populations and habitats. Surprisingly, we conclude that very few studies have addressed the mechanisms by which fragmentation will influence population dynamics or, in particular, the ways in which spatial scale mediate these effects. We conclude that the explicit consideration of scale is essential in discussions of habitat fragmentation and of optimal conservation strategies.

A landscape simulation model of winter foraging by large ungulates

Article

Oct 1993
ECOL MODEL

Ungulate winter grazing was simulated on simple random and actual landscape patterns using an individual-based modeling approach to explore the effect of landscape heterogeneity on foraging dynamics. The landscape was represented as a 100 × 100 grid with each cell considered to be either a resource or nonresource site. Random maps were generated by specifying the proportion, p, of the landscape occupied by resource sites. Actual landscape maps were obtained from the spatial arrangement of sagebrush-grassland habitats in subsections of northern Yellowstone National Park, Wyoming. Each resource site was assigned an initial forage abundance, and a specified number of ungulates were distributed randomly across the landscape on resource sites. Three alternative search-and-movement rules, which incorporated different movement scales and assumptions about ungulates' knowledge of the landscape, were compared. Grazing was simulated as a recipient-determined, donor-controlled flow with a nonlinear feedback. Daily energy balances were computed for each ungulate by subtracting energy cost from energy gain, and ungulates were assumed to die when they reached 70% of their lean body weight.

Individual Decisions and the Distribution of Predators in a Patchy Environment. II. The Influence of Travel Costs and Structure of the Environment

Article

Feb 1991

(1) We investigate properties of a model of predator distribution in relation to prey abundance, when the predation process is subject to: (i) non-negligible handling time and mutual interference; (ii) predator learning; (iii) intake rate maximization by individual predators. The model is a development of that of Bernstein, Kacelnik & Krebs (1988). (2) The independent variables are between-patch travel cost and structure of the environment. The outcome of the model is described in relation to the predictions of the ideal free distribution (IFD). We consider both the numerical distribution of predators and the mortality rate imposed on the prey population. (3) When travel cost is small, prey depletion is slow and interference is moderate, predators conform to the predictions of the IFD and prey mortality is density-dependent. (4) As travel cost is increased, rate-maximizing predators become more sedentary and the population settles at distributions far from the IFD. In common with all other disturbances of the predation process that impair the correlation between prey and predator densities, this causes mortality to approach density independence and later negative density dependence. (5) In semi-continuous environments where prey density is correlated between neighbouring patches, the slower the spatial rate of variation in prey density (the coarser the environmental grain), the poorer is the adjustment to the IFD. This effect is due to the predators' need for learning: when the environmental sample experienced within the reach of each individual predator is unrepresentative of the global average prey density (as it happens when the environmental grain is very coarse relative to migration range of predators), the predators cannot learn the global distribution of foraging opportunities and fail to take the policy that optimizes individual intake rate. (6) We discuss how these findings might account for observed patterns of mortality in real insects populations.

Dispersal and connectivity in metapopulations

Article

Jan 1991
BIOL J LINN SOC

Lennart Hansson

This paper reviews characteristics of dispersal that influence metapopulation functioning, such as releasing factors, density dependence, timing and types and health of dispersers. Economic thresholds, intraspecific conflicts and avoidance of inbreeding arc often regarded as the key ultimate or proximate (or both) causes of dispersal, but there is no consensus about the most important mechanisms. Dispersing individuals arc often considered to differ genetically from the residents but good supporting evidence has only been presented for some insect species. Sex and age differences in dispersal rates are most common in polygamous species and in long-lived species with many litters per female. A bimodal distribution of dispersal distances, earlier thought to be a common pattern, is probably an artifact, caused by habitat heterogeneity and varying survival of settled individuals. Dispersal distances are longer in poor environments. Habitat specialists are more affected by boundaries during dispersal than generalists. Dispersal just before or during the early reproductive season is common in certain species occupying early successional habitats. Dispersal increased both population and metapopulation size and persistence in plants, insects and small mammals.

Persistence in Patchy Irregular Landscapes

Article

Feb 1994

This paper presents a simulation and three approximations designed to study the effects of spatial clumping of patches in a metapopulation linked by costly dispersal. Assuming that all patches are identical and that each experiences a simple regime of density-independent uncorrelated extinction, we demonstrate that clumping enhances persistence of the population. We find a persistence threshold which depends on the leading eigenvalue of the matrix describing dispersal success between each pair of patches and show that this eigenvalue exceeds the mean dispersal success. An averaged approximation that uses a single statistic to describe each path, rather than the full matrix, successfully predicts the regional population size produced by the simulation and predicts a simple linear relationship between this statistic and the patch immigration rate. An approximation which ignores the detailed spatial structure fails to accurately predict the simulation results.

Plane geometry for naive searchers: some results of the simulation Rattlesnakec

Jan 1994
78A

Duvall

Towards a behavioral ecology of ecological landscapes

Abstract

No full-text available

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