Seasonal Patterns Of Habitat Use Research Articles

Seasonal patterns of habitat use of resident birds in Białowieża Forest and its links to post-disturbance management

Resident bird species staying in the same area year-round may face very different habitat conditions between seasons in temperate forests. This may cause resident forest birds to use different habitats during winter and spring. Furthermore, habitat use and their seasonal shifts could be additionally affected by large scale forest disturbances (e.g. outbreaks of bark beetles) and post-disturbance management, as they likely affect the availability of crucial resources for reproduction and survival. We investigated the impact of the European spruce bark beetle (Ips typographus) outbreak and post-outbreak management on winter and spring habitat use of 18 resident bird species in Białowieża Forest, Eastern Poland. We showed differences in habitat use of resident birds in winter and spring, at the level of species, community and three foraging guilds (i.e. invertivore bark foragers, invertivore arboreal gleaners and omnivores). First, bird species richness and bird abundance recorded at 111 sites in winter were not related or even showed a negative relationship with richness and abundance in spring, indicating that winter and spring bird diversity hotspots did not spatially overlap. Second, the wintering community as a whole, and the invertivore arboreal gleaners in specific, shifted their density towards more coniferous sites and increased their density at moderately salvage-logged sites, while decreasing their density at strongly salvage-logged sites. The wintering invertivore bark foragers shifted towards more outbreak sites (i.e. both salvage-logged and natural regeneration) and distributed more evenly along the natural regeneration – salvage-logged gradient. The distributions of habitat use were species-specific and there was no single habitat or level of disturbance preferred or avoided by all species or groups in spring or winter. This study highlights the importance of considering habitat use outside of the breeding season, when assessing habitat requirements of resident forest bird communities to evaluate the impact of post-disturbance management. In addition, it shows the significance of maintaining the heterogeneity of forest habitats to the wintering resident bird community, especially when deciding on post-disturbance management actions.

Seasonal habitat-use patterns of large mammals in a human-dominated landscape.

Large mammals in temperate climates typically display seasonal patterns of habitat use. However, these patterns are often overlooked because large mammals are usually surveyed at annual intervals. In addition, most studies focus on a single species and ignore other species with which the focal species could interact. Knowing seasonal patterns of habitat use in multiple species and understanding factors that cause these patterns can provide further detail on population dynamics and guide effective conservation planning. Here, using dynamic occupancy modeling, we analyze 11 years of camera-trap data collected in northwestern Anatolia, Turkey, to investigate seasonal habitat use of 8 large-mammal species: Brown Bear (Ursus arctos), Eurasian Lynx (Lynx lynx), Gray Wolf (Canis lupus), Red Fox (Vulpes vulpes), Wild Boar (Sus scrofa), Roe Deer (Capreolus capreolus), European Hare (Lepus europaeus), and Red Deer (Cervus elaphus). For each species, we study the strength of seasonality in habitat use and its dependence on human population density and elevation, which have been shown to affect distributions of species in the region. Although all species exhibited seasonality in habitat use, the strength of this seasonality varied among species; it was strongest in Wild Boar, Roe Deer, and Brown Bear. Moreover, except for Brown Bear, all species tended to avoid sites close to humans. The species responded differently to changing elevation; increasing elevation had both positive and negative effects on species-specific colonization and desertion probabilities, and these effects were likely related to either feeding habits or tendency to avoid humans. These results indicate that seasonality should be taken into consideration in population studies. However, because species differ, seasonality patterns should be identified separately for each species of interest, as differences in these patterns can explain the underlying dynamics of habitat-use patterns more accurately.

Individual and Temporal Variation in Use of Residential Areas by Urban Coyotes

Coyotes (Canis latrans) have established populations in most major urban centers across North America. While the risk of attacks on humans or their pets is low, the presence of carnivores in areas with high human use has resulted in increased public concern. Having a clearer understanding of which animals are more likely to interact with humans and when interactions are more likely to occur will help mitigate human-carnivore conflicts. Despite clear broad-scale patterns of human avoidance, human-coyote interactions occur most frequently in residential areas. Our purpose was to determine if use of residential areas varied consistently across individuals or time. We used locations from GPS collars deployed on 14 coyotes in the Greater Toronto Area, Ontario, Canada from 2012 to 2017 to fit a step selection function. Average (±SE) home range size estimates were 17.3 ± 4.6 km2 for resident coyotes and 102.8 ± 32.9 km2 for non-residents. We found that coyotes used natural areas more (β = 0.07, SE = 0.02, p < 0.0001), and roads (β = −0.50, SE = 0.13, p < 0.0001) and residential areas (β = −0.79, SE = 0.21, p = 0.0001) less during the day than at night. We also found that coyotes were more likely to use residential areas in the breeding season from January to April (β = 0.69, SE = 0.20, p = 0.0007) and the pup rearing season from May to August (β = 0.54, SE = 0.13, p < 0.0001) than in the dispersal season from September to December. Lastly, we found that resident coyotes were less likely to use residential areas than non-resident coyotes (β = −1.13, SE = 0.26, p < 0.0001). As far as we are aware, our study is the first to identify the seasons when coyotes are more likely to use residential areas. The seasonal patterns in habitat use that we observed reflect patterns that have been previously reported for human-coyote conflicts. Our results demonstrate that reducing the availability of anthropogenic food sources in residential areas, particularly in the winter and spring, should be a priority for managers aiming to reduce human-coyote conflict in urban areas.

Evaluating connections between nitrogen cycling and the macrofauna in native oyster beds in a New England estuary.

Recent efforts to quantify biogeochemical and ecological processes in oyster habitats have focused on provision of habitat and regulation of the nitrogen cycle. However, it is unclear how these two processes may interact. In this study, seasonal patterns of habitat use and nitrogen removal from natural oyster beds were quantified for comparison with nearby bare sediment in Green Hill Pond, a temperate coastal lagoon in Rhode Island USA. Relationships were tested between benthic macrofaunal abundance and nitrogen removal via denitrification and burial in sediments. Nitrogen removal by oyster bio-assimilation was quantified and compared with nearby oyster aquaculture. Despite limited differences in habitat use by macrofauna, there were fewer non-oyster benthic organisms (e.g., filter-feeders, detritivores) where oysters were present, possibly due to competition for resources. Additionally, low rugosity of the native oyster beds provided little refuge value for prey. There was a shift from net N removal via denitrification in bare sediments to nitrogen fixation beneath oysters, though this change was not statistically significant (t(96) = 1.201; p = 0.233). Sediments contained low concentrations of N, however sediments beneath oysters contained almost twice as much N (0.07%) as bare sediments (0.04%; p < 0.001). There was no difference in tissue N content between wild oysters and those raised in aquaculture nearby, though caged oysters had more tissue per shell mass and length, and therefore removed more N on a shell length basis. These oyster beds lacked the complex structure of 3-dimensional oyster reefs which may have diminished their ability to provide habitat for refugia, foraging sites for macrofauna, and conditions known to stimulate denitrification.

Seasonal patterns in habitat use by the harvest mouse (Micromys minutus) and other small mammals.

Seasonal patterns in habitat use by the harvest mouse (Micromys minutus) and other small mammals.

Seasonal patterns in habitat use by the harvest mouse (Micromys minutus) and other small mammals

Abstract The ecology of the harvest mouse (Micromys minutus) is poorly understood, partly because it is a difficult species to monitor. It is commonly associated with reedbeds, where evidence suggests that it experiences strong seasonal fluctuations in abundance. However, it is unknown whether these fluctuations are caused by real changes in population size, or by movement between habitats. This study investigated seasonal changes in population size and habitat use by harvest mice, and other small mammal species, by trapping the reedbed and three associated habitat types: woodland, pasture and arable land. A sampling effort of 9887 trap bouts across nine months, resulted in 70 captures of harvest mice, as well as wood mice (N = 1022), bank voles (N = 252), field voles (N = 9), common shrews (N = 86) and pygmy shrews (N = 7). The reedbed was the habitat with the most captures and highest diversity. Harvest mice were caught exclusively in the reedbed at the beginning of autumn. Wood mice and bank voles experienced fluctuations in population numbers and wood mice also showed seasonal variation in habitat use. Our study supports the idea that harvest mice undergo extreme seasonal fluctuations in abundance in reedbeds, but these do not appear to be related to changes in habitat use.

The distribution of plant consumption traits across habitat types and the patterns of fruit availability suggest a mechanism of coexistence of two sympatric frugivorous mammals.

Understanding the mechanisms governing the coexistence of organisms is an important question in ecology, and providing potential solutions contributes to conservation science. In this study, we evaluated the contribution of several mechanisms to the coexistence of two sympatric frugivores, using western lowland gorillas (Gorilla gorilla gorilla) and central chimpanzees (Pan troglodytes troglodytes) in a tropical rainforest of southeast Cameroon as a model system. We collected great ape fecal samples to determine and classify fruit species consumed; we conducted great ape nest surveys to evaluate seasonal patterns of habitat use; and we collected botanical data to investigate the distribution of plant species across habitat types in relation to their “consumption traits” (which indicate whether plants are preferred or fallback for either gorilla, chimpanzee, or both). We found that patterns of habitat use varied seasonally for both gorillas and chimpanzees and that gorilla and chimpanzee preferred and fallback fruits differed. Also, the distribution of plant consumption traits was influenced by habitat type and matched accordingly with the patterns of habitat use by gorillas and chimpanzees. We show that neither habitat selection nor fruit preference alone can explain the coexistence of gorillas and chimpanzees, but that considering together the distribution of plant consumption traits of fruiting woody plants across habitats as well as the pattern of fruit availability may contribute to explaining coexistence. This supports the assumptions of niche theory with dominant and subordinate species in heterogeneous landscapes, whereby a species may prefer nesting in habitats where it is less subject to competitive exclusion and where food availability is higher. To our knowledge, our study is the first to investigate the contribution of plant consumption traits, seasonality, and habitat heterogeneity to enabling the coexistence of two sympatric frugivores.OPEN RESEARCH BADGES This article has earned an Open Data Badge for making publicly available the digitally‐shareable data necessary to reproduce the reported results. The data is available at https://datadryad.org/resource/doi:10.5061/dryad.ms65f29.

The temporal niche and seasonal differences in predation risk to translocated and resident woodland caribou (Rangifertaranduscaribou)

Mountain caribou are an endangered ecotype of woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)) that continue to decline, ultimately, due to habitat loss and, proximately, due to predation. A particularly imperilled population of mountain caribou was experimentally augmented with 19 northern caribou, a geographically distinct ecotype, from northern British Columbia. We examined seasonal variation in risk of predation by cougars (Puma concolor (L., 1771)) to the translocated caribou with comparison to resident caribou. Our basic approach followed the Movement Ecology Paradigm, in particular the interplay among why move, and when and where to move. We applied a cluster analysis framework on space-use patterns of GPS radio-collared animals to determine biologically relevant seasons. Then we examined the spatiotemporal similarity in habitat use between caribou groups and cougars across these seasons. This analysis included a control group of caribou from the donor herd that were not translocated. Five resident caribou seasons, two donor caribou seasons, and two cougar seasons were identified. Resident caribou remained at high elevations year-round and primarily selected habitats not used by cougars. In contrast, translocated caribou tended to occupy low-elevation habitats extensively used by cougars, resulting in predation of eight translocated caribou, six of which were by cougars. We concluded that the translocated caribou did not adopt the predator avoidance strategies of resident caribou, rendering them more vulnerable to predation. We make recommendations for future herd augmentations, notably that donor caribou should be of the same ecotype, have similar seasonal patterns of habitat use and associated behavioural repertoires, and be exposed to the same complex of predators.

Summer-restricted migration of green turtles Chelonia mydas to a temperate habitat of the northwest Pacific Ocean

The foraging habitats of green turtles Chelonia mydas range from tropical to temperate areas. Previous studies have generally been biased toward tropical and sub-tropical areas; hence, available data do not accurately describe the species' foraging activity in temperate areas. To reveal seasonal patterns of habitat use in temperate areas, we conducted a by-catch survey, a markre- capture study, and satellite tracking of green turtles along the Sanriku Coast, a temperate zone in the northwest Pacific Ocean. From July through November of 2005 to 2014, 78 green turtles were captured during a period of relatively high water temperatures (16 to 24°C). Straight carapace length (SCL) ranged from 36.8 to 85.6 cm (average: 49.4 ± 11.4 cm; n = 78), indicating that most of the turtles were juveniles. In the markrecapture study, 14 of 72 tagged turtles were recaptured 5 to 426 d after release, 12 of which were recaptured south of the release point. Based on satellite track- ing data, 3 turtles travelled more than 500 km to reach southern habitats, where water temperature was warmer (13 to 25°C) than along the Sanriku Coast (4 to 22°C). Our results revealed that the Sanriku Coast is a seasonally restricted habitat for juvenile green turtles, which migrate to southern habitats in winter, and that turtles in temperate areas migrated longer than those in tropical and sub-tropical areas. This is the first report of seasonal migration of juvenile green turtles to a temper- ate habitat in the northern Pacific Ocean.

Seasonal changes in movement and habitat use by Southern Ground-Hornbills in the South African lowveld

Southern Ground-Hornbills Bucorvus leadbeateri are Endangered in South Africa and there is a concerted effort to reverse their population decline. They live in groups year round, with only the alpha pair breeding, raising at most one chick per year. Each group has a home range of 50–100 km2, but there are few data for their spatial habitat use within this range. Understanding the factors affecting Southern Ground-Hornbill movement patterns is useful to assess habitat management options for the species, to select sites for artificial nests and to identify suitable areas for reintroduction initiatives. We report daily and seasonal patterns of habitat use by four groups in the Associated Private Nature Reserves, north-east South Africa, based on data from GPS-satellite tags. Daily travel distances averaged 7.4 ± 2.2 km d−1 but were greater during the breeding season, although birds were constrained to forage close to their nest, and were lower in winter, when birds ranged more widely. Hourly travel distances were affected by time of day, season, temperature and group. Birds travelled farthest per hour in the morning, decreasing in the afternoon in winter. However, in summer hourly travel distances were bimodally distributed, with a minimum during the middle of the day when ambient temperatures exceed 25 °C. Acacia-dominated vegetation and riparian habitats were favoured disproportionately during the heat of the day in summer, presumably because they offer more shade than other habitats. Optimal habitat configurations for ground-hornbills include a mosaic of habitat types, including open areas for foraging and dense trees for shade.

Heterogeneidad ambiental y su relación con la diversidad y abundancia de la comunidad de peces en un sistema costero del Golfo de México

The coastal lagoons of Veracruz, Gulf of Mexico, include a great variety of biological resources. These resources, especially fish communities, have been barely described and that require more ecological studies. With this aim, this investigation analyzed the spatial and temporal variation of diversity, abundance and assemblages of the fish community and its relationship with physical-chemical parameters of the Chica-Grande coastal system. For this, eight defined sites were monthly sampled for water characteristics and fish community composition (10min hauls of 1 500m2 a shrimp trawl net), between September 2005 and November 2006. The spatial-temporal variation of physical-chemical parameters, allowed the definition of two contrasting environments according to salinity, temperature, transparency, dissolved oxygen and depth gradients. A total of 1 947 fishes were collected for a total weight of 57.88kg. From these, 22 species, 20 genera and 14 families were identified; and four species were new records for the system. As it was detected for the physical-chemical conditions, the diversity of the fish community also showed a spatial gradient, with high values (H'=2.37, D=3.35, J'=0.82) in the brackish habitat, and low ones in freshwater environments. Fish abundance did not show such a marked gradient response, however, it was higher in the freshwater habitat. The highest diversity (H'=2.05) and species richness (D=2.99) was recorded during the North winds ("nortes") months (November-February), while density and biomass were higher (0.034 ind./m2, 1.42g/m2) during the rainy months (July-October). The Importance Value Index (IVI) defined six dominant species accounting for 77.8% of the fish abundance and 87.9% of total catch by weight. The Canonical Correspondence Analysis (CCA) showed that the fish-habitat relationship was explained by 68% of total variance for the two first axes, where salinity, transparency and temperature changes were the most important environmental variables in determining the fish community composition and distribution. In this study, spatial gradients of environmental variables explained the changes in fish species composition and abundance; while the temporal gradients, the fish community structure and its relationship with seasonal patterns of habitat use by the species during their life cycles.

A review of wild boarSus scrofadiet and factors affecting food selection in native and introduced ranges

AbstractThe wild boarSus scrofais an omnivore with one of the largest geographical ranges of all species. However, no synthesis exists on its diet, feeding behaviour and factors affecting food selection in its native and introduced ranges.A literature review and a test of effect size revealed significant differences in wild boar diet composition in native and introduced ranges. Wild boar diet is dominated by plant material (∼90%) in both ranges, but animal matter and fungi are consumed in greater proportions in the introduced range than in the native range. Food items frequently include agricultural crops (especially in the native range) and endangered animal species (especially in the introduced range). Energy requirements, food availability, and seasonal and geographical variations are major factors influencing food selection by wild boar. These factors may also interact with human activities (e.g. agricultural crops, supplementary feeding) to influence diet composition further.Dietary studies should be more rigorous and consistent across ranges to allow better comparisons. A detailed study of diet in combination with seasonal patterns of habitat use could provide key information such as target species and susceptible habitats on which management efforts should focus.

The role of season and social grouping on habitat use by Mute Swans (Cygnus olor) in a lowland river catchment

Capsule The Mute Swan, a large generalist herbivore, showed patterns of habitat use influenced by social grouping and season. Territorial swans showed strong preferences for river and lake habitat in all seasons, while the non-territorial birds known to cause grazing conflicts preferred river in summer–autumn and pasture in winter–spring. Aims To quantify the habitat preferences across different seasons of two types of Mute Swan social group, territorial and non-territorial, and assess the implications for the grazing conflict between swans and valuable plant communities. Methods Repeated surveys of the River Frome catchment, Dorset, UK, over a two-year period allowed us to record the numbers of swans in each habitat type. An electivity index was used to calculate habitat preference scores for territorial and non-territorial swans across different seasons. Results We found strong seasonal switches in habitat use for both territorial and non-territorial swans, but preferences for some habitats differed between these social groupings. In particular, non-territorial swans preferred pasture in winter and spring, and river in summer and autumn, while territorial swans preferred river and lake habitats throughout the year. Conclusion The Mute Swan, a large generalist herbivore that can cause grazing damage to river plant communities, showed patterns of habitat use influenced by social grouping and season. These seasonal patterns of habitat use suggest that the grazing conflict with the river plant community caused by flocks of non-territorial swans is currently limited to summer and autumn.

Seasonal patterns of habitat use by insectivorous bats in a subtropical African agro‐ecosystem dominated by macadamia orchards

AbstractWe report on acoustic surveys of insectivorous bats conducted during seven months of the year using ANABAT recordings in two habitats (macadamia orchards and adjacent riparian bush) in a subtropical agro‐ecosystem in northern South Africa. We defined two functional foraging groups of bats based on their echolocation calls: (i) open‐air foragers (family Molossidae) having narrow‐band, low‐frequency, low duty cycle calls; and (ii) clutter‐edge foragers (families Miniopteridae and Vespertilionidae), having broad‐band, higher frequency, low duty cycle calls. Bat activity (number of bat passes) was not significantly influenced by habitat. Total bat activity and activity of both functional groups varied significantly between seasons, being highest in summer and autumn (coinciding with annual peaks in numbers of Twin spotted (Bathycoelia natalicola) and Green (Nezara spp) Stinkbugs, order Heteroptera, family Pentatomidae, and Macadamia Nut Borer moths, Cryptophlebia ombrodelta) and lower in winter and spring. No significant effect of moon phase was detected, either on total activity or activity of the two functional groups. We postulate that the significant pattern of seasonality of commuting and/or foraging activity of bats in macadamia orchards (which is more marked in open‐air foragers) may be driven by the seasonal abundance of pest insects such as stinkbugs and Macadamia Nut Borer moths.

Seasonal habitat use by greater horseshoe bat Rhinolophus ferrumequinum (Chiroptera: Rhinolophidae) in Changbai Mountain temperate forest, Northeast China

Abstract We performed acoustic surveys at 78 sites around one bat colony to examine seasonal patterns of habitat use by greater horseshoe bats. Insect abundance and temperature were determined in each season. Bat diets were assessed by analysing faecal composition. Greater horseshoe bats tended to forage in mixed broadleaved and mixed broadleaved and coniferous woodland and were rarely found foraging in coniferous woodland. Bat activity in mixed broadleaved woodland and woodland glades significantly decreased from June to September. There were significant seasonal differences in the frequency of utilization of different habitats. Distance from the day roost had significant effects on bat activity only in June and July. The diet of greater horseshoe bats was clearly dominated by Lepidoptera and Coleoptera, with some variations with seasons. The seasonal variation of habitat use by greater horseshoe bats probably depended on resource availability that fluctuates over space and time. These results have important implications for the conservation of this bat species. Cluttered broadleaved woodland and mixed broadleaved woodland constitute an important target for conservation. Instead of reforestation with the non-native pure coniferous woodland, planting and maintaining broadleaved forests or mixed forests should be encouraged.

Obtaining New Insights for Biodiversity Conservation from Broad-Scale Citizen Science Data

Increasing public engagement in volunteer science1, either through data collection2 or processing3, is both raising public awareness of science and gathering useful information for scientists. While the payoffs of citizen science4 are potentially large, achieving them requires new approaches to data management and analysis that can only result from strong cross-disciplinary collaborations. This is especially true in ecology and conservation biology, where historically the understanding of species’ responses to environmental change has been constrained by the limited spatial5 or temporal scale6 of available data. Here we describe collaborative research in ecology, computer science, and statistics to generate essential information for conservation management of North American birds: accurate dynamic bird distributions models based on habitat associations across much of North America. Unique is our ability to describe the broad-scale dynamics of seasonal bird distributions and the associated seasonal patterns of habitat use. Our source of bird distribution data is eBird7, an online bird checklist program that currently gathers more than 74,000 checklists monthly from a large network of contributors. Our results were made possible through a data intensive scientific workflow8 that includes analytical methods merged from the fields of machine learning and statistics. We believe that this novel approach of data collection, synthesis, analysis, and visualization will serve as a hallmark for future research initiatives, with broad applicability across many scientific domains.

Obtaining New Insights for Biodiversity Conservation from Broad-Scale Citizen Science Data

AbstractIncreasing public engagement in volunteer science1, either through data collection2 or processing3, is both raising public awareness of science and gathering useful information for scientists. While the payoffs of citizen science4 are potentially large, achieving them requires new approaches to data management and analysis that can only result from strong cross-disciplinary collaborations. This is especially true in ecology and conservation biology, where historically the understanding of species’ responses to environmental change has been constrained by the limited spatial5 or temporal scale6 of available data. Here we describe collaborative research in ecology, computer science, and statistics to generate essential information for conservation management of North American birds: accurate dynamic bird distributions models based on habitat associations across much of North America. Unique is our ability to describe the broad-scale dynamics of seasonal bird distributions and the associated seasonal patterns of habitat use. Our source of bird distribution data is eBird7, an online bird checklist program that currently gathers more than 74,000 checklists monthly from a large network of contributors. Our results were made possible through a data intensive scientific workflow8 that includes analytical methods merged from the fields of machine learning and statistics. We believe that this novel approach of data collection, synthesis, analysis, and visualization will serve as a hallmark for future research initiatives, with broad applicability across many scientific domains.

Patterns of macro and microhabitat use of two rodent species in relation to agricultural practices

AbstractHabitat selection may reflect the location of the home ranges or the allocation of shelter and foraging sites within a given habitat. We studied seasonal patterns of habitat use by Akodon azarae and Calomys laucha at two spatial scales: between maize fields and their weedy edges (macrohabitats), and associations of rodents captures with vegetation variables at the trap site level (microhabitats). We evaluated if the different habitat uses were related to disturbances generated by practices associated to maize cycle. A. azarae used mainly field edges, but it showed an increased use of maize fields when the crop reached maturity in summer. Contrarily, C. laucha used maize fields in a higher proportion than edges in all seasons. C. laucha was more influenced by microhabitat characteristics than A. azarae. C. laucha was present in sites with abundant dicot weeds when maize was growing up, while it was associated to sites with weeds with scarce cover in stubble maize fields. Before harvesting, both species were segregated at the microscale within maize fields. A. azarae was related to sites with high availability of green plant cover and C. laucha occupied low‐quality sites, probably attributed to differences in their diets. We conclude that the pattern of habitat use by both species is best predicted at the macrohabitat scale, and when they are impoverished and present internal heterogeneity, there is selection at microhabitat scale of those better sites. While A. azarae responds to changes in vegetation cover and habitat structure associated to agricultural practices, C. laucha uses cropfields in an opportunistic way, affected by interspecific competition.

The use of habitat and time by lizards in a tropical deciduous forest in western Mexico

Ecological studies on seasonally dry tropical forest herpetofauna are scarce and those focused on interspecific relations of lizards in this endangered ecosystem are even fewer. This study evaluates general and seasonal patterns in time and habitat use among four lizard species (Anolis nebulosus, Sceloporus melanorhinus, S. utiformis, and Urosaurus bicarinatus) in a protected area of dry tropical forest in western Mexico. Data were gathered by visual surveys along 12 linear parallel transects located in an undisturbed habitat. Anolis nebulosus showed a bimodal pattern in daily activity whereas the other species exhibited unimodal patterns of activity. Seasonality only affected the general activity patterns of S. melanorhinus and U. bicarinatus. With the exception of A. nebulosus and S. melanorhinus, statistical differences were found for all pairwise comparisons of general and seasonal patterns of habitat use. The use of leaf‐litter and low perches in arboreal species was higher during the dry season, probably in response to higher food availability in these habitats. As expected, environmental seasonality affects both activity time and habitat use by lizards. Results suggest greater differences in habitat use than in time of activity among species. The data also indicate complementary use of time and space by these lizard species: species showing similar activity patterns exhibit greater differences in their habitat use. Predation could be an important factor affecting the use of habitat and time by the four lizard species. Los estudios ecológicos de la herpetofauna de los bosques tropicales secos son escasos y aquellos enfocados a las relaciones ínterespecíficas en lagartijas de este ecosistema fuertemente amenazado son aún más raros. Este estudio evalúa el uso del tiempo y del hábitat de cuatro especies de lagartijas (Anolis nebulosus, Sceloporus melanorhinus, S. utiformis y, Urosaurus bicarinatus) en un área protegida en el occidente de México al comparar los patrones generales y estacionales. La información se obtuvo basándose en 12 transectos visuales ubicados en bosque intacto. Anolis nebulosus registró un patrón bimodal de actividad diaria mientras que en el resto fue unimodal, pero aparentemente, la estacionalidad solo afecto los patrones generales de S. melanorhinus y U. bicarinatus. A excepción de A. nebulosus y S. melanorhinus, todas las comparaciones intraespecificas de los patrones generales y estacionales del uso del hábitat mostraron diferencias estadísticamente significativas. El uso de la hojarasca y perchas mas bajas, en las especies arborícolas, fue mayor durante la época de sequía probablemente en respuesta a una mayor disponibilidad de alimento en esos hábitats durante ese tiempo. Como se esperaba, la estacionalidad puede afectar el uso del tiempo y hábitat en lagartijas. Los resultados sugieren la posibilidad de un mayor uso diferencial del hábitat que del tiempo y la ocurrencia de un uso complementario de ellos: las especies con patrones de actividad más similares difieren más en su uso del hábitat. La depredación puede tener un efecto importante en el uso del tiempo y hábitat de estas especies de lagartijas.

Intraspecific and interspecific variation in use of forest-edge habitat by snakes

Variation in use of edge habitat among populations and species of snakes should reflect underlying causes (e.g., thermal ecology, prey availability) and consequences (e.g., predation on birds' nests) of habitat selection. We compared the habitat use of ratsnakes, Elaphe obsoleta (Say in James, 1823), in Illinois and Ontario and compared habitat use by ratsnakes and racers, Coluber constrictor (L., 1758), in Illinois. Ratsnakes in Illinois used upland forest more and forest edges less than ratsnakes in Ontario. Female ratsnakes in Illinois used edges less than males, regardless of their reproductive status. Relative to ratsnakes, racers preferred forest edges and avoided forest interior. Female racers used edges more than males, especially while gravid. These results, and most of the seasonal patterns in habitat use, were broadly consistent with variation expected from differences in thermoregulatory needs, although other factors potentially influencing habitat use cannot be ruled out. Although it has been proposed that some forest fragmentation is likely to be beneficial for ratsnakes in Canada, such fragmentation may be detrimental to ratsnakes in Illinois but beneficial to racers. Thus, relative to forest-interior species, edge-nesting birds should be more vulnerable to predation by ratsnakes in Ontario, and fragmentation should increase the vulnerability of forest birds to nest predation by racers.