Journal of Mammalogy

Pônzio, Marcella do Carmo; Pasqualotto, Nielson; Alberici, Vinicius; Paolino, Roberta Montanheiro; Rodrigues, Thiago Ferreira; Chiarello, Adriano G

doi: 10.1093/jmammal/gyad085pmid: N/A

Mammalian carnivores are often vulnerable to the conversion of natural habitat. Although some species might be frequent in anthropogenic areas, it is not entirely clear how they use modified landscapes, particularly in tropical agroecosystems. Here, we investigated how Puma (Puma concolor) and Maned Wolf (Chrysocyon brachyurus) used three disturbed areas in southeastern Brazil. We sampled 205 camera stations and estimated species occupancy (Ψ) and detection probabilities (p), interpreted as probability of use and frequency of use, respectively. Our models predicted that both species extensively used the study areas (model-averaged probability of use of 0.65 for pumas and 0.50 for maned wolves). Puma frequency of use was higher in stations further from human structures and areas of savanna. Maned Wolf frequency of use was lower in forest-dominated stations and in a more protected and forested study area. Puma probability of use was high in stations closer to watercourses, while Maned Wolf probability of use was higher in unpaved roads and stations farther from human structures. Our findings suggest that pumas and maned wolves may be able to adapt their use of space in agroecosystems featuring riparian corridors and unpaved roads. Nevertheless, our data also reveal possible impacts to carnivore populations in these systems, such as the degradation of riparian environments, road mortality, and human construction avoidance. Thus, some caution is warranted in considering highly modified environments as safe habitats for large carnivores, until further data on the density and vital rates of these species in agricultural-dominated areas have been quantified.

Haarsma, Anne-Jifke; Jongejans, Eelke; Duijm, Elza; van der Graaf, Carolien; Lammers, Youri; Sharma, Milan; Siepel, Henk; Gravendeel, Barbara

doi: 10.1093/jmammal/gyad096pmid: 38059006

Animals with large energy requirements are forced to optimize their hunting strategy, which may result in differentiation of the diet between sexes and across seasons. Here, we examined spatiotemporal variation in the diet of both sexes of the Pond Bat Myotis dasycneme, a species known to have spatial segregation of sexes when the young are born and lactating. Fecal pellets were collected from live animals for a period of 15 years at various locations in the Netherlands. A total of 535 pellets were successfully analyzed by microscopy and an additional 160 pellets by DNA metabarcoding. Morphological and molecular analyses showed that the diet of pregnant and lactating pond bats differed significantly from the diet of females with no reproductive investment. Further analyses of the data showed that pregnant female pond bats are highly dependent on small prey and pupae, mainly nonbiting midges and mosquitoes (Diptera: Chironomidae and Culicidae). These insects can be found in large quantities in peatlands intersected with shallow waterways, the habitat type in which female pond bats were observed more often than males. Our results suggest that during pregnancy the spatial segregation of sexes coincides with sex-specific diets, which might reflect habitat selection based on energy requirements, in addition to lowered intraspecific competition.

Esnaola, Amaiur; Larrañaga, Aitor; González-Esteban, Jorge; Elosegi, Arturo; Aihartza, Joxerra

doi: 10.1093/jmammal/gyad061pmid: 38059010

Traditionally, researchers have assessed diet selection by comparing consumed versus available taxa. However, taxonomic assignment is probably irrelevant for predators, who likely base their selection on characteristics including prey size, habitat, or behavior. Here, we use an aquatic insectivore, the threatened Pyrenean Desman (Galemys pyrenaicus), as a model species to assess whether biological traits help unravel the criteria driving food and habitat preferences. We reanalyzed data from a previous taxonomy-based study of prey selection in two contrasting streams, one with excellent conservation status and the other affected by diversion for hydropower and forestry. Available and consumed prey were characterized according to nine biological traits, and diet selection was estimated by comparing availability—measured from Surber net samples, and consumption—analyzed by metabarcoding desman feces. Traits offered a biologically coherent image of diet and almost identical selection patterns in both streams, depicting a highly specialized rheophilic predator. Desmans positively selected prey with a preference for fast flow and boulder substrate, indicating their preferred riffle habitat. On the other hand, they positively selected prey with larger but not the largest potential size, living in the water column or the litter, and not inside sediments. They also chose agile prey, swimmers or prey attached to the substrate, prey with high body flexibility, and prey living exposed and clustered in groups. Overall, our results offer a picture of desman diet preference and point to biological traits as being better than taxonomic identity to describe the diet preference of consumers.

Crandall, Kirsten E; Olson, Link E; Millien, Virginie

doi: 10.1093/jmammal/gyad083pmid: N/A

Mammals are predicted to vary in body size following Bergmann’s rule, with individuals found at higher latitudes in colder temperatures being larger in size compared to conspecifics occurring at lower latitudes in warmer temperatures. Body size is similarly expected to vary temporally, with a decrease in size through time due to recent climate warming. While Bergmann’s rule is well-supported in mammals, there is increasing evidence of exceptions to the rule. Here, we present patterns of size variation in 17 North American mammal species using five morphological traits (condylobasal skull length, skull width, maxillary toothrow length, body weight, and head-and-body length) to determine if size varies predictably for each species in space and time. We found little support for a widespread Bergmannian pattern for these species at a broad spatial scale (across North America) and a contemporary temporal scale (the past 120 years). The effects of latitude or year on each trait were highly variable with three types of responses: an increase, a decrease, or no change in size across space or through time. Spatial size trends were detected more often than temporal size trends, as the temperature range was significantly larger in space than through time. Body weight (the most variable trait) and head-and-body length were more likely to conform to Bergmann’s rule than craniodental measurements. We did not detect any changes in size variability with latitude, and our study species either increased or decreased in size variability over time. Our findings demonstrate that size variation in mammals is highly context-dependent. As such, caution is needed when using rules of body size variation to predict the future response of species to climate warning while valid in theory, it is likely too simplistic of an approach.

O’Brien, Kaedan; Irmis, Randall B; Brenner Coltrain, Joan; Dalmas, Daniel Martin; Derieg, Katrina M; Evans, Thomas; Richards, Eric S; Richards, Fumiko M; Rickart, Eric A; Faith, J Tyler

doi: 10.1093/jmammal/gyad093pmid:

Weller, Theodore J; Clerc, Jeff; Lau, Matthew J; Johnson, Nels G

doi: 10.1093/jmammal/gyad088pmid: N/A

For temperate-zone mammals, seasonal changes in weather and food availability often govern energy allocation. In addition, energy allocation strategies usually differ between males and females. Bats are an interesting group in which to evaluate energetic trade-offs as they are highly mobile and lead energetically demanding lives in habitats across a variety of seasonally variable climates. We evaluated year-round changes in body mass and fuel load for three species of bats in northern California: Silver-haired Bat (Lasionycteris noctivagans), California Myotis (Myotis californicus), and Yuma Myotis (Myotis yumanensis). Silver-haired bats are considered migratory species with females likely migrating farther than males. The two species of myotis are considered residents. Body mass of all species peaked in late autumn and was at a minimum during spring. We calculated a fuel load index to normalize size difference between species and sexes. We used sex- and season-specific multiple linear regression models to evaluate rates of change in seasonal fuel loading. Rates of change in fuel load did not differ among species or sexes except for male silver-haired bats that increased fuel loads rapidly during summer. Interspecific comparisons provided valuable insights into the energy allocation and overwintering strategies of these species and are an important initial step toward understanding their ecology over the full annual cycle.

Sasse, D Blake; Perry, Roger W

doi: 10.1093/jmammal/gyad079pmid: N/A

The Eastern Small-footed Bat (Myotis leibii) inhabits mountainous areas of the eastern United States and generally roosts in cliff faces and talus slopes. However, the difficulty of accessing these sites has limited research on this species. We studied survival rates of eastern small-footed bats by capturing bats roosting in crevices between sections of concrete guardrails on bridges in the Ozark mountains of northern Arkansas from 2014 to 2021. We accumulated 1,413 bat captures (1,050F; 363M) of 283 individual females and 198 individual males sampled over 8 years and determined apparent annual survival of female bats using Cormack–Jolly–Seber survival models. Only 1 of 30 bats tested positive for the presence of Pseduogymnoascus destructans, a fungus causing white-nose syndrome (WNS) which is responsible for significant declines in populations of some North American bat species, when all maternity colonies were sampled in the spring of 2019. Overall apparent annual survival of all females was 0.643, with first-year juvenile survival of 0.472 and adult (ages 1–6) survival of 0.744, approximately 58% greater than first-year survival. Apparent annual survival did not differ greatly among the sites or among years. We found no significant decline or increase in overall number of bats among all sites during the 8 years of study. Stability in both the number of bats encountered and their survival rates suggests that the impact of WNS on these colonies has been marginal.

Hooven, Nathan D; Williams, Kathleen E; Hast, John T; McDermott, Joseph R; Crank, R Daniel; Springer, Matthew T; Cox, John J

doi: 10.1093/jmammal/gyad091pmid: N/A

Due to the vulnerability of neonatal ungulates, selection of a birth site can have important implications for offspring survival and thus fitness of the mother. We studied parturition site selection in cow Elk in southeastern Kentucky, United States, using a use–availability framework to evaluate the effects of landscape variables sampled at multiple spatial grains on the relative probability of use of parturition sites. We identified 81 Elk parturition sites during May–Aug 2020–2022 and fit several candidate resource selection function models using a sample of 24,314 random locations to characterize habitat availability. Using an information-theoretic approach to rank candidate models, we identified two top-performing models (cumulative ωi = 0.97), which indicated that at fine spatial grains (~10- and 30-m pixels) parturient cow Elk selected for intermediate canopy cover and lower terrain ruggedness compared to available locations. At coarse grains (250–1,000-m buffers/neighborhoods), Elk selected against vegetation greenness/biomass, for higher topographic positions, for closer proximity to major roads, and with higher solar radiation potential. We also found evidence that Elk responded positively to forest/open edge densities at coarse grains, demonstrating that calving habitat throughout the Kentucky Elk Restoration Zone is associated with heterogeneous landscapes resulting from surface mine reclamation. As a result, habitat management actions should aim to increase patchy, early successional shrub cover on gentle topography.

Werdel, Ty J; Piper, Colleen W; Ricketts, Andrew M; Peek, Matthew S; Ahlers, Adam A

doi: 10.1093/jmammal/gyad065pmid: N/A

Many carnivore populations have experienced substantial declines and are at increased risk of extinction, mainly due to negative interactions with humans and biological traits that make them susceptible to habitat loss and fragmentation, often driven by agricultural expansion. Carnivore community richness is likely influenced by many direct and indirect factors, though it is unclear how carnivore communities are structured in prairie landscapes that are considered one of the most imperiled ecosystems worldwide. Our goal was to identify landscape-scale effects driving carnivore community richness in a contemporary agro-prairie ecosystem. We used 3 years of presence data (2018–2020) from camera-trap sites (n = 381) distributed across western Kansas, United States and developed a structural equation model (SEM) to test a priori hypotheses explaining carnivore richness. Measures of water availability, native prairie, and agriculture—as well as sampling effort (i.e., days cameras were active)—were all positively associated with carnivore richness. Additionally, our index of rabbit abundances at sites had a direct positive effect on our measure of carnivore richness. Our SEM explained 42% of the variance in carnivore richness (χ2 = 8.76, d.f. = 21, P = 0.99) in this human-dominated landscape. Our results suggest that carnivore communities in agro-prairie landscapes are structured through multiple direct and indirect landscape-scale pathways. Contemporary agro-prairie mosaics may act as filters for the agricultural tolerance of carnivores, with species more vulnerable to native prairie loss becoming locally extirpated.

Dedeban, Emilie; Webber, Quinn M R; Laforge, Michel P; Robitaille, Alec L; Vander Wal, Eric

doi: 10.1093/jmammal/gyad081pmid: N/A

Environmental and climatic variation drive animal migration. Animals must adjust their behavioral strategies, for example, habitat selection, to match best variation in resources whose value likely varies with conditions such as weather. For example, climate change makes processes such as snowmelt and the emergence of vegetation less predictable at the scale of months or weeks. Furthermore, climate change makes meteorological conditions unpredictable—or dynamic—at the scale of days and hours. The profitability of selecting any particular resource may vary according to local meteorological condition. We studied the impact of dynamic weather conditions on fine-scale movement strategies and resource selection during spring migration of adult female Woodland Caribou (Rangifer tarandus). We assessed the role played by static resources such as open, lichen, and closed forest habitats and their role in a context-dependent of dynamic weather conditions, including temperature, precipitation, and changing snow water equivalent. We tested the role of static resources and dynamic conditions in three contexts: (1) whether caribou were encamped or moving using hidden Markov models; state-specific habitat selection for, and the interaction between, resources and conditions while (2) encamped and (3) moving. Weather conditions influenced the probability of moving or staying encamped, and the probability of selecting for a resource, which likely reflects the profitability of a given resource in a particular condition. The probability of staying encamped in the forest increases as temperature increases, and the probability of selecting an open area is higher when precipitation is lower. We highlight how meteorological conditions modify the selection of a static resource and likely the profitability of a given resource. The resource utility to a consumer is increasingly susceptible to climate change-induced effects.