Relative Habitat Use Research Articles

Drivers of variability in surf zone habitat use by sandy beach fish: Unwitting citizen scientists reveal detailed spatiotemporal patterns

Surf zones of sandy beaches are among the most heavily impacted aquatic ecosystems, yet are of critical ecological importance for inshore fish and fisheries. Knowledge of the drivers of fish habitat use in surf zones is needed across broad scales to advise conservation and fisheries management, but sampling capabilities can be limited in spatio-temporal extent and resolution. The lesser weever Echiichthys vipera is a small, benthic, venomous fish that dominates surf zone fish assemblages in Northwest Europe and inflicts painful stings on beachgoers. This study capitalises on an extensive record of E. vipera sting incidents to characterise variations in surf zone habitat use in relation to key physical environmental factors. Sting incidents, standardised by water user numbers, are used as a proxy for E. vipera abundance across 77 beaches throughout Southwest England, with 2 h resolution, from April–November 2018. General Additive Models indicated a clear peak in E. vipera abundance at spring low tides, in the afternoons of summer months, under calmer wave conditions and at higher levels of solar irradiance. Although the order of significance differed, human water users were also driven by the same variables, compounding sting interactions over time. Key physical variables did not explain spatial variation in E. vipera abundance, although there was a weak relationship with sea surface temperature, and some evidence that reflective beaches are unsuitable. Physical factors explained more spatial variation in human water users, who gathered at more dissipative beaches with greater wave heights. This detailed study of an important surf zone fish reveals clear drivers of temporal variation in habitat use, yet infers wide suitability of beaches varying in the key physical drivers of sandy shore ecology.

The effect of soil parameters and earthworm abundance on the fine-scale nocturnal habitat use of the Eurasian woodcock (Scolopax rusticola).

The Eurasian woodcock prefers habitats where its main prey, earthworms, can be found in higher densities. Although they are forest-dwelling birds, they regularly visit pastures and natural grasslands at night, where earthworm abundance is generally higher. However, there is little information on fine-scale habitat use in relation to variation in habitat characteristics and prey availability, particularly beyond the breeding season. In our study, we investigated if the nocturnal occurrence of woodcocks during migratory stopover periods differed between two neighbouring fields, or management units, with similar vegetation structure, and if within-field variation in the spatial patterns of woodcock sightings were associated with fine-scale earthworm densities and soil parameters. Specifically, we used GPS tracking data of two tagged woodcocks and direct observation data to study patterns of occurrence of birds in a mixed forest-pasture landscape in Hungary during pre- and post-breeding periods. We compared these patterns with fine-scale soil characteristics and earthworm abundance, acquired by field sampling. We found that the field with higher earthworm abundance was visited by woodcocks more frequently, and this correlation was similarly observed at the intra-field level. Our results demonstrate that woodcocks select foraging sites with higher earthworm densities at multiple spatial scales, both between fields (coarse scale), and within fields (fine-scale). Considering that woodcocks tended to return to the same field to forage at night, the strong associations between occupancy and resources provide a basis for developing habitat management strategies at the field level for conservation. As earthworm densities and soil parameters are good indicators of woodcock foraging habitat, measuring those variables, at least at a coarse scale, could aid in predicting important habitats for the species across the landscape.

Performance of unmarked abundance models with data from machine‐learning classification of passive acoustic recordings

AbstractThe ability to conduct cost‐effective wildlife monitoring at scale is rapidly increasing due to the availability of inexpensive autonomous recording units (ARUs) and automated species recognition, presenting a variety of advantages over human‐based surveys. However, estimating abundance with such data collection techniques remains challenging because most abundance models require data that are difficult for low‐cost monoaural ARUs to gather (e.g., counts of individuals, distance to individuals), especially when using the output of automated species recognition. Statistical models that do not require counting or measuring distances to target individuals in combination with low‐cost ARUs provide a promising way of obtaining abundance estimates for large‐scale wildlife monitoring projects but remain untested. We present a case study using avian field data collected in the forests of Pennsylvania during the spring of 2020 and 2021 using both traditional point counts and passive acoustic monitoring at the same locations. We tested the ability of the Royle–Nichols and time‐to‐detection models to estimate the abundance of two species from detection histories generated by applying a machine‐learning classifier to ARU‐gathered data. We compared abundance estimates from these models with estimates from the same models fit using point‐count data and to two additional models appropriate for point counts, the N‐mixture model and distance models. We found that the Royle–Nichols and time‐to‐detection models can be used with ARU data to produce abundance estimates similar to those generated by a point‐count‐based study but with greater precision. ARU‐based models produced confidence or credible intervals that were on average 31.9% (±11.9 SE) smaller than their point‐count counterpart. Our findings were consistent across two species with differing relative abundance and habitat use patterns. The higher precision of models fit using ARU data is likely due to higher cumulative detection probability, which itself may be the result of greater survey effort using ARUs and machine‐learning classifiers to sample significantly more time for focal species at any given point. Our results provide preliminary support for the use of ARUs in abundance‐based study applications, and thus may afford researchers a better understanding of habitat quality and population trends, while allowing them to make more informed conservation recommendations and actions.

Interannual site fidelity by Svalbard walruses

The Arctic is experiencing rapid reductions in sea ice, affecting all ice-dependant species. In the present study we examine interannual seasonal movements and habitat use in relation to sea ice coverage for one of the Arctic endemic marine mammals. We tagged 40 male walruses (Odobenus rosmarus) in the Svalbard Archipelago with custom-designed tusk-mounted GPS loggers. Twelve of these animals provided tracks that lasted 1–6 years. Eleven of the walruses displayed clear seasonal migratory behaviour between summer foraging areas and winter breeding areas. Individuals showed high inter-individual variation, but clear site fidelity, using the same areas in consecutive years despite variable sea ice conditions. The walruses swam 5225–10,406 km per year and travelled remarkably similar distances between years on an individual basis. The phenology of migration was not impacted by sea ice concentrations or daylight length but was consistent at the individual level, suggesting endogenous drivers. Sea ice concentrations influenced movement behaviour with animals showing more tortuous paths when in areas with heavy sea ice, possibly searching for polynyas where females reside. Ongoing climate change is expected to drastically change walrus habitat, and it remains to be seen if walruses will be able to shift from their fixed seasonal migratory routines.

Environmental DNA reveals fine‐scale spatial and temporal variation of marine mammals and their prey species in a Scottish marine protected area

AbstractMarine mammal foraging grounds are popular focal points for marine protected area (MPA) implementation, despite being temporally dynamic, requiring continuous monitoring to infer prey availability and abundance. Marine mammal distributions are assumed to be driven by their prey in foraging areas, but limited understanding of prey distributions often prevents us from exploring how shifting prey availability impacts both seasonal and long‐term marine mammal distributions. Environmental DNA (eDNA) metabarcoding could enhance the understanding of marine mammal habitat use in relation to their prey through simultaneous monitoring of both. However, eDNA applications focused on marine mammals or predator–prey dynamics have been limited to date. In this study, we assess spatiotemporal changes in the distribution and abundance of cetaceans, minke whales (Balaenoptera acutorostrata), bottlenose dolphins (Tursiops truncatus) and harbor porpoises (Phocoena phocoena) in relation to key prey species in a newly established MPA, employing eDNA metabarcoding. We recovered 105 molecular operational taxonomic units (OTUs) from marine vertebrates using two primer sets targeting 12S and 16S genes, along with 112 OTUs from a broader eukaryotic primer set targeting 18S rRNA. Overall, key forage fish prey species, sandeels and clupeids, were the most abundant teleost fishes detected, although their availability varied temporally and with distance from shore. We also found clear spatial partitioning between coastal bottlenose dolphins and the more pelagic minke whales and harbor porpoises, paralleling availability of their main prey species. Other species of conservation interest were also detected including the critically endangered European eel (Anguilla anguilla), Atlantic bluefin tuna (Thunnus thynnus), and the invasive pink salmon (Oncorhynchus gorbuscha). This study demonstrates the application of eDNA to detect spatiotemporal trends in the occurrence and abundance of cetacean predators and their prey, furthering our understanding of fine‐scale habitat use within MPAs. Future long‐term monitoring of predator–prey dynamics with eDNA could improve our ability to predict climate‐induced shifts in foraging grounds and enhance rapid responses with appropriate management actions.

Exploring habitat use and movement patterns of humpback whales in a reoccupation area off Brazil: A comparison with the Abrolhos Bank

AbstractAfter the worldwide moratorium on whaling, humpback whale populations began to recover, reoccupying former areas of use, as also observed on the Brazilian coast. Abrolhos Bank represents the area of greatest humpback whale concentration but the number of individuals to the north has increased, as has happened in the region of Serra Grande. To compare relative abundance, habitat use, and movement patterns between a well‐established breeding and a reoccupation area, visual monitoring from land‐based stations was performed: 160 days in the Abrolhos Archipelago located on the Abrolhos Bank and 133 days in Serra Grande in 2014, 2015, 2018, and 2019. While relative abundance varied annually in the Abrolhos Archipelago, it gradually increased in Serra Grande, surpassing the number registered in Abrolhos in 2019. Group composition frequency was similar between areas except for mother and calf accompanied by one or more escorts, which were more frequent in Abrolhos. Despite similar movement speed and linearity values, whales in Serra Grande had a higher reorientation rate. Monitoring different areas occupied by this population supports decisions about spatial management of the Brazilian coast in relation to the implementation of anthropogenic activities, especially in areas where whales have recently returned to occupy.

Cougars, wolves, and humans drive a dynamic landscape of fear for elk.

To manage predation risk, prey navigate a dynamic landscape of fear, or spatiotemporal variation in risk perception, reflecting predator distributions, traits, and activity cycles. Prey may seek to reduce risk across this landscape using habitat at times and in places when predators are less active. In multipredator landscapes, avoiding one predator could increase vulnerability to another, making the landscape of fear difficult to predict and navigate. Additionally, humans may shape interactions between predators and prey, and induce new sources of risk. Humans can function as a shield, providing a refuge for prey from human-averse carnivores, and as a predator, causing mortality through hunting and vehicle collisions and eliciting a fear response that can exceed that of carnivores. We used telemetry data collected between 2017 and 2021 from 63 Global Positioning System-collared elk (Cervus canadensis), 42 cougars (Puma concolor), and 16 wolves (Canis lupus) to examine how elk habitat selection changed in relation to carnivores and humans in northeastern Washington, USA. Using step selection functions, we evaluated elk habitat use in relation to cougars, wolves, and humans, diel period (daytime vs. nighttime), season (summer calving season vs. fall hunting season), and habitat structure (open vs. closed habitat). The diel cycle was critical to understanding elk movement, allowing elk to reduce encounters with predators where and when they would be the largest threat. Elk strongly avoided cougars at night but had a near-neutral response to cougars during the day, whereas elk avoided wolves at all times of day. Elk generally used more open habitats where cougars and wolves were most active, rather than altering the use of habitat structure depending on the predator species. Elk avoided humans during the day and ~80% of adult female mortality was human caused, suggesting that humans functioned as a "super predator" in this system. Simultaneously, elk leveraged the human shield against wolves but not cougars at night, and no elk were confirmed to have been killed by wolves. Our results add to the mounting evidence that humans profoundly affect predator-prey interactions, highlighting the importance of studying these dynamics in anthropogenic areas.

Diet-habitat ecology of invasive tilapia and native fish in a tropical river catchment following a tilapia invasion

Many species of tilapia (a collection of fish species from the cichlidae family) have biological traits that make them successful invaders. Widespread herbivory has been observed across tilapia species, however knowledge on habitat preferences and tilapia interactions with native fish food webs is limited. This study was conducted three years after spotted (Pelmatolapia mariae) and Mozambique (Oreochromis mossambicus) tilapia were detected in the Mitchell River catchment, northern Australia. Tilapia diet and habitat preferences and their trophic position in native fish food webs was determined using a combination of stomach content, stable isotope, and habitat assessment analyses. Plant material was the most abundant item in tilapia stomachs, and some stomachs also contained other items in small quantities, such as fish eggs, small shrimp, and bivalves. Some niche overlap occurred between P. mariae and native omnivore or herbivore fish species. Macrohabitat type (in-channel (no tilapia), floodplain (no tilapia), weir (tilapia present)) was related to native fish food web structure, with weir food webs showing similarities to floodplain food webs. Floodplain habitats including creeks and wetlands were also most similar to weir habitats and may therefore be most at risk of colonization as tilapia spread throughout the catchment. This study clearly demonstrated that the successful rapid invasion of these two tilapia species is linked to suitable habitat with abundant food that fuels growth and reproduction. These findings increase understanding of diet related habitat use during new tilapia invasions and trophic interactions with native species.

A preliminary study of the winter roosting behaviour of four woodland passerines

ABSTRACT Capsule Radio-tracking of four woodland passerine species reveals variation in winter roost site selection within and between species. Aims To evaluate methods for studying winter roosting behaviour in woodland passerines and to collect preliminary data on intra- and inter-specific differences in roost site characteristics and spatial arrangement. Methods Ten woodland birds (three Eurasian Blackbirds Turdus merula, three Dunnocks Prunella modularis, two Great Tits Parus major and two European Robins Erithacus rubecula), were fitted with a tail-mounted Lotek PicoPip AG337 VHF radio tag (January to March 2022). Tagged birds were located by triangulation, and nightly winter roost locations identified and characterized. A geographic information system was used to quantify roost site fidelity, roosting height and types of habitats used. Results Manual tracking of birds with radio tags is a cost effective and appropriate method for studying passerine winter roosting behaviour. Sample sizes were too small to allow exploration of significant differences between sites, age and sex. European Robins showed the greatest site fidelity in relation to between-night roost positions, with Eurasian Blackbird, Great Tit and Dunnock being more variable in the sites chosen between nights. Eurasian Blackbird and Great Tit roost sites were generally higher above the ground (up to 6 m), compared to European Robins and Dunnocks (all sites less than 4 m above the ground). Eurasian Blackbirds varied the most in the number of habitats used for roost sites, and European Robins showed the least variation. Only three out of 11 habitat types (bramble Rubus sp, laurel Prunus sp. and Sycamore Acer pseudoplatanus with Ivy Hedera helix) were used by more than one species as a roosting habitat. Conclusion Further research should focus on: (1) habitat use in relation to relative availability; (2) increasing samples sizes to allow comparison of factors such as age, sex and sites; (3) the impact of supplementary feeding on roosting behaviour; (4) quantifying the thermal properties of roost sites.

Space use by Callosciurus erythraeus in a fragmented landscape

Abstract Tree squirrel species that are successful invaders may modify their behaviour according to the characteristics of the invaded community. We studied the use of space by Callosciurus erythraeus in the main invasion focus established in Argentina, where suitable habitat is highly fragmented and immersed in a rural–urban landscape of the Pampas region. We evaluated habitat use in relation to the dominant arboreal vegetation (evergreen vs. deciduous) based on seasonal trapping data throughout two years and home range size and overlap based on seasonal radio-tracking data in two consecutive years. We captured 476 squirrels with a higher trapping success in areas dominated by evergreen vegetation. Effective home ranges were smaller for females (0.10–0.77 ha, n = 12) than for males (0.9–3.78 ha, n = 3). We observed home range overlap between and within both sexes, suggesting no or low territoriality. Our results support the two working hypotheses on the relatively higher use of areas dominated by evergreen vegetation and on the relatively small home range sizes and large overlapping areas associated to high squirrel density. The flexibility in the use of different type of arboreal patches would be another attribute linked to the invasion success of this species.

What makes Sanriku waters the southernmost habitat of northern fur seals? Winter-spring habitat use in relation to oceanographic environments.

The waters off Sanriku (located on the northeastern coast of Honshu Island, Japan) provide the southernmost habitats of northern fur seals (Callorhinus ursinus) during winter and spring in the western North Pacific. The southward flowing cold Oyashio current and northward-flowing warm Kuroshio extension mix there, making the area highly productive. Northern fur seals migrate into these waters from the breeding rookeries for feeding, and the locations of the southern margins of their habitats vary yearly. The key questions for understanding the seasonal migration patterns are "why" and "how" the species utilize these waters as the southernmost habitat. We estimated the density and abundance of northern fur seals using standard line-transect theory combined with habitat modeling. The spatial patterns of animal density were analyzed using generalized additive models with seven static and dynamic environmental covariates, and those covariates were selected based on Akaike's information criterion (AIC). The lowest AIC model included depth, sea surface temperature, slope, and gradient in sea surface temperature. This model estimated well the spatial patterns of the density of the species, in which fur seals were widely distributed in the study areas, but less frequently encountered between the isobaths 100 m and 200 m. These spatially separated habitats suggest that the shelf break and offshore front play an important role in creating the feeding grounds of fur seals. On the other hand, sea surface temperature positively correlated with fur seals' density up to 14°C. This may indicate that further warm waters work as a temperature barrier, and fur seals concentrate on the edge of suitable temperature ranges.

Quantifying spatial characteristics of the Bowhead Whale Aerial Survey Project (BWASP) survey design

The Bowhead Whale Aerial Survey Project (BWASP) has been conducted annually since 1979 in the Alaskan Beaufort Sea to monitor the distribution and relative abundance of the Bering-Chukchi-Beaufort (BCB) stock of bowhead whales (Balaena mysticetus) during their autumn migration. BWASP was created to specifically address broad-scale research and management questions related to bowhead whale ecology, with particular interest in the potential effects of oil and natural gas exploration, development and production activities on the BCB bowhead whales. With elevated concerns about climate change, increasing oil and gas activities and the forecasted increase in vessel traffic, it is expected that interest in the BWASP dataset will also increase in order to evaluate effects of these anthropogenic activities on BCB bowhead whales and indigenous whaling. The following analysis quantified the spatial characteristics of the BWASP survey design and provided guidelines for the types of investigations that the BWASP data can potentially address. Sampling lags (transect spacing) in the BWASP survey design of approximately 20km along the east/west axis of the study area limit the spatial scale of phenomena that can be detected using data from a single BWASP survey. Therefore, BWASP data are relatively uninformative for studying variability in distribution or relative abundance along the east/west axis over short time scales (one survey) and within small areas measuring less than approximately 20km. In addition, computer simulations showed spatial heterogeneity in the long-term survey coverage probability (the probability that a given location will be included in a survey having an assumed effective search width under the BWASP survey design). Pooled transects created from simulated surveys resulted in a repeating diamond pattern in which coverage probability was low. Analyses incorporating data from many BWASP surveys should account for this spatial heterogeneity, via either the survey coverage probabilities or quantification of survey effort; otherwise estimates of variables such as relative density, density, or habitat use may be biased. The BWASP surveys have increased understanding of the broad-scale patterns of bowhead distribution, relative abundance and behaviour. The utility of this dataset in informing other questions will depend upon the scale of the ecological phenomena under investigation and the analytical scales used to address the questions.

Agroecosystem Ecology of Northern Deermice (Peromyscus maniculatus bairdii) and White-Footed Deermice (P. leucopus noveboracensis) in the Inner Bluegrass of Kentucky

Peromyscus leucopus (White-Footed Deermouse) and Peromyscus maniculatus (North American Deermouse) are 2 widespread rodent species in North America, with North American Deermice more ecologically diverse and widely distributed than White-footed Deermice. Commonly, White-Footed Deermice are ecological generalists, and North American Deermice are ecological specialists. In the Inner Bluegrass Region of Kentucky, these 2 species are sympatric in agroecosystems habitats, including the University of Kentucky North Farm. This farm was the most trapped location in central Kentucky from 1950 to 1968, with results indicating the White-Footed Deermoouse was the more common of these species. Trapping from 1995 to 2015 found that North American Deermice were caught rarely. Our study examined agroecosystems habitats at the UK North Farm, including all perennial and annual habitats, to determine the relative abundance and habitat use by both these species. In our study, North American Deermice was the most commonly captured species; it was trapped rarely in perennial habitats but much more frequently in annual crops. Perennial clover fields and Medicago sativa (Alfalfa) were the 2 exceptions; however, these are short crops with exposed soil between rows. Essentially, North American Deermice were observed in the agricultural equivalent of early successional habitat. In contrast, White-Footed Deermice were captured in both perennial and annual habitats, but more commonly in perennial habitats, the exception being annual Salvia hispanica (Chia) fields where dense, green plants produced a thick canopy. Overall, the best predictor of habitat for North American Deermice was bare, exposed soil, whereas the best predictor for White-Footed Deermice was dense growth and overhead cover.

The coastal breeding habitat of Bank Swallows (Riparia riparia) in an Atlantic Canada National Park: assessing habitat use in relation to availability

Understanding bird habitat selection has become a priority in conservation, particularly for bird species facing long-term population declines. The Bank Swallow ( Riparia riparia (Linnaeus, 1758)), a species whose eastern distribution limit is in Atlantic Canada, declined by 98% between 1970 and 2011, prompting its listing as a threatened species in 2017. Its decline is hypothesized to be due in part to habitat loss and, hence, this study aimed to identify critical habitats within a protected area along Prince Edward Island. We used two types of survey to examine the availability and use of three breeding habitats: dunes, glacial till, and sandstone cliffs. A goodness-of-fit test revealed that the habitats were not used in proportion to their availability. Among them sandstone cliffs and, to a lesser extent, till cliffs were used significantly more than expected (i.e., selected). Instead, sand dunes were used less (i.e., avoided) as a breeding habitat. These results suggest that Bank Swallow selection is driven by characteristics associated with the sandstone and till habitats, and more attention and possibly protection should be given to them. Further studies should also explore whether similar patterns of selection are evident in the region’s historical records and in similar coastline areas.

An assessment of relative habitat use as a metric for species’ habitat association and degree of specialization

In order to understand species’ sensitivity to habitat change, we must correctly determine if a species is associated with a habitat or not, and if it is associated, its degree of specialization for that habitat. However, definitions of species’ habitat association and specialization are often static, categorical classifications that coarsely define species as either habitat specialists or generalists and can fail to account for potential temporal or spatial differences in association or specialization. In contrast, quantitative metrics can provide a more nuanced assessment, defining species’ habitat associations and specialization along a continuous scale and accommodate for temporal or spatial variation, but these approaches are less widely used. Here we explore relative habitat use (RHU) as a metric for quantifying species’ association with and degree of specialization for different habitat types. RHU determines the extent of a species’ association with a given habitat by comparing its abundance in that habitat relative to its mean abundance across all other habitats. Using monitoring data for breeding birds across Europe from 1998 to 2017; we calculate RHU scores for 246 species for five habitat types and compared them to the literature-based classifications of their association with and specialization for each of these habitats. We also explored the temporal variation in species’ RHU scores for each habitat and assessed how this varied according to association and degree of specialization. In general, species’ RHU and literature-derived classifications were well aligned, as RHU scores for a given habitat increased in line with reported association and specialization. In addition, temporal variation in RHU scores were influenced by association and degree of specialization, with lower scores for those associated with, and those more specialized to, a given habitat. As a continuous metric, RHU allows a detailed assessment of species’ association with and degree of specialization for different habitats that can be tailored to specific temporal and/or spatial requirements. It has the potential to be a valuable tool for identifying indicator species and in supporting the design, implementation and monitoring of conservation management actions.

Characterization of Jaguar Utilization Distributions in the Brazilian Pantanal

Jaguars (Panthera onca) have been eradicated from 50% of their historical range across Mexico, Central America, and South America. The Brazilian Pantanal in west-central Brazil represents a stronghold of core habitat for the species and is an important site for conservation. Habitat in the Pantanal is threatened largely due to expanding human activity causing habitat loss and fragmentation, making remaining habitat vitally significant. This study seeks to characterize the utilization distributions of jaguars in the area to better understand the habitat use and spatial ecology of a threatened species. GPS locations taken from 13 jaguars were used to calculate estimates of kernelhomesrangesatthe50% (core range)and 95% (home range)isopleth levels. These ranges were used to quantify habitat use in relation to land cover types. Patterns of distribution heavily followed waterways, perhaps following that of their main prey,caimans(Caiman crocodilus yacare). Wetlands were the most heavily utilized among all jaguars at the 95% home range followed by grasslands. However, at the 50% core range level there was a shift in greater utilization of forest habitat over grassland. Additionally, females generally had smaller home ranges than that of males and exhibited less overlap between home ranges(27 km2) than between male home ranges(217 km2) – a key indicator of female spatial avoidance.

Analyzing the relative habitat use by Siberian cranes on migratory stopover sites: A traditional wetland species switching to croplands for food resources

Analyzing the relative habitat use by Siberian cranes on migratory stopover sites: A traditional wetland species switching to croplands for food resources

Mixed-severity wildfire shapes habitat use of large herbivores and carnivores

Ecological disturbance is a driving force that structures ecosystems and shapes landscape pattern. Wildfire is a widespread form of ecological disturbance, and in some vegetation communities fires are increasing in extent and severity. Across the gradient of fire severity, fire can have both positive and negative effects on animals, where some species require mature climax vegetation conditions and other species select for early successional stages. However, further work is necessary to understand how large mammalian herbivore and carnivore populations respond to the gradient of fire severity. The overall objective of this research was to understand the relative roles of fire, landscape, and human factors across the gradient of fire severity on occupancy and/or relative habitat use of large herbivores (i.e., elk and mule deer) and carnivores (i.e., black bear, mountain lion, and gray wolf) seven years post fire. We predicted that animals would increase use of areas characterized by higher fire severity (moderate, moderate/high, or high fire severity) and heterogeneity, where food resources were expected to be greatest. In addition, road density could either increase or decrease animal use of areas, where some animals might increase use near roads due to increased forage along roadsides or decrease use due to higher human activity. Remote wildlife (RW) cameras sampled the gradient of fire severity seven years post a large mixed-severity wildfire (Wallow Fire, year 2011, 2,177 km2) in the White Mountains of Arizona, USA. We evaluated RW camera data using single-species occupancy and Royle-Nichols (relative habitat use) models. As predicted, large mammals (black bear, elk, mountain lion, mule deer, and wolves) exhibited high occupancy and/or habitat use in relation to higher levels of fire severity and/or fire heterogeneity, which was likely related to bottom-up factors related to increased food resources. Some species (black bear and elk) also exhibited relatively high use of unburned forest. Elk reduced use of areas with higher road density, likely to avoid human activity, whereas mule deer increased use of areas with high road density. Mixed-severity wildfire may provide important resources, including pulses of food in early successional forests. Thus, allowing fire-adapted forests to experience mixed-severity wildfire is predicted to benefit some large herbivore and carnivore populations. If high occupancy and/or habitat use by wildlife in areas experiencing higher fire severity and heterogeneity translates into increased populations of animals, wildfire might be beneficial to humans, focal wildlife populations, and fire-adapted ecosystems.

Post-fire movements of Pacific marten (Martes caurina) depend on the severity of landscape change

BackgroundWildfires and forestry activities such as post-fire salvage logging are altering North American forests on a massive scale. Habitat change and fragmentation on forested landscapes may threaten forest specialists, such as Pacific marten (Martes caurina), that require closed, connected, and highly structured habitats. Although marten use burned landscapes, it is unclear how these animals respond to differing burn severities, or how well they tolerate additional landscape change from salvage logging.MethodsWe used snow tracking and GPS collars to examine marten movements in three large burns in north-central Washington, USA (burned in 2006) and central British Columbia, Canada (burned in 2010 and 2017). We also assessed marten habitat use in relation to areas salvage-logged in the 2010 burn. We evaluated marten path characteristics in relation to post-fire habitat quality, including shifts in behaviour when crossing severely-disturbed habitats. Using GPS locations, we investigated marten home range characteristics and habitat selection in relation to forest cover, burn severity, and salvage logging.ResultsMarten in the 2006 burn shifted from random to directed movement in areas burned at high severity; in BC, they chose highly straight paths when crossing salvage-blocks and meadows. Collared marten structured their home ranges around forest cover and burn severity, avoiding sparsely-covered habitats and selecting areas burned at low severity. Marten selected areas farther from roads in both Washington and BC, selected areas closer to water in the 2006 burn, and strongly avoided salvage-logged areas of the 2010 burn. Marten home ranges overlapped extensively, including two males tracked concurrently in the 2010 burn.ConclusionsAreas burned at low severity provide critical habitat for marten post-fire. Encouragingly, our results indicate that both male and female marten can maintain home ranges in large burns and use a wide range of post-fire conditions. However, salvage-logged areas are not suitable for marten and may represent significant barriers to foraging and dispersal.

Influence of Juniper on Montezuma Quail Habitat Use in Texas

ABSTRACTMontezuma quail (Cyrtonyx montezumae) inhabit oak (Quercus spp.)‐juniper (Juniperus spp.) woodlands throughout Mexico and the southwestern United States. In Texas, USA, Montezuma quail occur in the Edwards Plateau and Trans‐Pecos Mountains and Basins (Trans‐Pecos), 2 ecoregions with contrasting juniper patterns. Ashe juniper (Juniperus ashei) dominates in the Edwards Plateau and has been increasing over decades, whereas alligator juniper (Juniperus deppeana) is a co‐dominant in the Trans‐Pecos and appears to have stable Montezuma quail populations. Our objectives were to compare between ecoregions the relative abundance and habitat use of Montezuma quail in relation to juniper and quantify the influence of juniper on key features of Montezuma quail habitat (grass height, grass cover, forb cover, and forb species richness). We conducted a study from March–August 2018‒2020 in the Edwards Plateau (Kinney and Edwards counties) and Trans‐Pecos ecoregions (Jeff Davis County) to evaluate these objectives. We conducted call‐back surveys to estimate relative abundance (number of detections/hr) of Montezuma quail and identify used locations. We collected vegetation data at a micro‐scale (16‐m) at used (n = 32–30 points) and random locations (n = 70–60 points) in each ecoregion. Relative abundance of Montezuma quail was considerably lower in the Edwards Plateau (0.06 ± 0.01 detections/survey hr; ± SE) than in the Trans‐Pecos (1.10 ± 0.30 detections/survey hr). In addition, Montezuma quail selected areas of low Ashe juniper cover (<23% cover), density (<7 trees/80 m2), and height (<2 m) in the Edwards Plateau but selected areas of high alligator juniper cover (>18% cover), density (>4 trees/80 m2), and height (2–8 m) in the Trans‐Pecos. Moreover, Ashe juniper cover had a significant, negative influence on herbaceous features, whereas alligator juniper exerted little to no influence. Our results suggest that these 2 juniper species have contrasting effects on Montezuma quail space use and their habitat, possibly as a result of the contrasting influence of these junipers on herbaceous understory. Creating habitat for Montezuma quail in the Edwards Plateau generally will involve the reduction of Ashe juniper and creating patches that possess juniper trees of small stature (<2 m) with low amounts of cover (<23%) and density (<7 trees/80 m2), whereas management in the Trans‐Pecos will require site‐specific assessments based on current alligator juniper influence. © 2021 The Wildlife Society.