Glaucomys Volans Research Articles

Notes on the nest sites, reproductive activity, and a new record of the southernmost population of Glaucomys volans (Sciuridae: Rodentia)

ABSTRACT Glaucomys volans underwoodi was recently rediscovered in Honduras after 43 years since its last record; the population in the eastern region of the country is considered the southernmost within the distribution of this species. However, there is a lack of ecological information about this squirrel in their disjunct populations through Central America. We describe the nest sites used by this species in Honduras and give reproductive data for the southern populations for the first time. Also, we add the northernmost record for the species in Honduras. Restrained activities are needed to conserve the last remnants of pine forests and their mammals within the country.

Assessing responses to heat in a range-shifting, nocturnal, flying squirrel.

Over the last few decades North American flying squirrels (Glaucomys spp.) have experienced dramatic northward range shifts. Previous studies have focused on the potential effects of warming winter temperatures, yet the hypothesis that rising summer temperature had a role in these range shifts remained unexplored. We therefore sought to determine the effect of high environmental temperatures on the thermoregulation and energetics of flying squirrels in an area of the Northeast of North America with a recent species turnover. Unable to find a logistically feasible population of the northern species (Glaucomys sabrinus), we focused on Southern Flying Squirrels (G. volans). Using flow-through respirometry, we measured the relationship between metabolic rate, evaporative water loss, and body temperature at high ambient temperatures. We also measured core body temperature in free-ranging flying squirrels using temperature-sensitive data loggers. We detected no significant increase in metabolic rate up to ambient temperatures as high as 40 °C. However, evaporative water loss increased at temperatures above 36.2 °C. Free-ranging body temperature of flying squirrels followed a circadian pattern with a ~2 °C difference between active and resting phase modal body temperatures. Rest-phase body temperatures were influenced by environmental temperatures with higher resting temperatures observed on days with higher daily maximum ambient temperatures but not to an extent that energy or water costs were significantly increased during rest. We found that, due to a relatively high level of thermal tolerance, high ambient temperatures are unlikely to cause an energetic strain on Southern Flying Squirrels. However, these findings do not preclude negative impacts of high ambient temperatures on the northern species, and these may still play a role in the changing distributions of Glaucomys in North America.

Microhabitat use of northern and southern flying squirrels in a recent hybrid zone

Secondary contact of closely related species may lead to hybridization if reproductive isolation is incomplete. We examined the role of habitat use as a factor contributing to reproductive isolation of northern ( Glaucomys sabrinus (Shaw, 1801)) and southern ( Glaucomys volans (Linnaeus, 1758)) flying squirrels in an area of secondary contact in Ontario, Canada. Specifically, we looked at summer microhabitat use within sites of sympatry and allopatry to test for evidence of reinforcement due to diverging habitat use. We also examined differences in broad-scale habitat features at woodlots to determine predictors of species occurrence across sites. We used 18 years (2002–2019) of flying squirrel summer capture data from six sites along a north–south transect and microhabitat data from vegetation surveys conducted during summer 2016. We found microhabitat variables to be weak predictors of trap-level flying squirrel presence, and we found no evidence of divergence in microhabitat use over the 18 years. Further, we found latitude, not broad-scale habitat, was the strongest predictor of site-level flying squirrel occurrence. Overall, our findings suggest that microhabitat-based isolation is not being reinforced between flying squirrels; however, hybridization may be limited to areas where climate and habitat are suitable for both species.

Landscape genetics of the Southern Flying Squirrel (Glaucomys volans) in the northeastern United States

Abstract Understanding how changes in landscape properties influence common species is relevant as it allows us to identify patterns that could be shared with co-distributed species that occupy the same landscapes. The northeastern United States (NE-USA: New York state and the six states of New England) is heavily urbanized and affected by continuous and prolonged anthropogenic activities, leading to intensive landscape fragmentation and loss of natural forests. Here, we used a landscape genetics approach to explore the genetic diversity and structure of the Southern Flying Squirrel, Glaucomys volans, and how resulting patterns may be related to landscape fragmentation and forest loss in the NE-USA. To study G. volans genetic variation and population structure, we amplified and genotyped 10 microsatellites loci from DNA extracted from tissue samples stored in biological collections and natural history museums. To assess the influence of landscape on gene flow and connectivity, we used two genetic distances metrics–proportion of shared alleles and codominant marker, and tested two landscape cost models approaches–least cost path and isolation by resistance. We identified three genetic clusters, with low but significant genetic differentiation between them. We did not find correlation between geographic distance and genetic variation in these populations. According to landscape models, land cover and elevation were the best predictors of genetic connectivity of G. volans, although were poorly related to genetic distances. Our results suggest that gene flow occurs between G. volans populations across the NE-USA despite the changed landscape configuration, implying potential dispersal of individuals between patches. Nonetheless, individuals from the eastern periphery of the distribution may have been temporarily isolated in the past due to historical deforestation. The current regeneration of hardwood forests represents a positive outlook for the genetic integrity of G. volans populations in the NE-USA because more possibilities for corridors and patches of habitable forests emerge. These changes would improve the connectivity of the species in the region and avoid possible local extinction events.

Unseen for 43 years! A new occurrence of Glaucomys volans (Linnaeus, 1758) (Rodentia, Sciuridae) in Honduras

We report an occurrence of Glaucomys volans (Linnaeus, 1758) in Honduras after 43 years since its last verified record. The observation was in an area in which forestry and silvicultural activities are carried out for the sustainable exploitation of logging and timber of Pinus oocarpa in Las Lechuzas, department of Olancho (eastern Honduras). This record supports the initiation of new conservation activities in areas in which forestry is being implemented; population studies and the protection of their refuges are the priorities at its southernmost locality.

Techniques for documenting and quantifying biofluorescence through digital photography and color quantization

Ultraviolet (UV) induced biofluorescence is being discovered with increasing frequency across the tree of life. However, there is not yet a standardized, low-cost, photographic methodology used to document, quantify, and minimize sources of bias that often accompany reports made by researchers new to fluorescence imaging. Here, a technique is described to create accurate photographs of biofluorescent specimens as well as how to use these images to quantify fluorescence via color quantization, using open-source code that utilizes K-means clusters within the International Commission on Illumination L*a*b* (CIELAB) color space. The complexity of photographing different excitation and emission wavelengths and methods to reduce bias from illumination source and/or camera color sensitivity (e.g., white balance) without the use of modified equipment is also addressed. This technique was applied to preserved southern flying squirrel (Glaucomys volans) specimens to quantify the color shift between illumination under visible and UV light and analyze variation among specimens. This relatively simple methodology can be adapted to future studies across a range of fluorescent wavelengths and project goals, and assist future research in which unbiased photographs and analyses are key to understanding the physiological and ecological role of biofluorescence.

Thermal niche partitioning and phenology of Nearctic and Palearctic flea (Siphonaptera) communities on rodents (Mammalia: Rodentia) from five ecoregions.

Seasonality of fleas (Siphonaptera) may be due to species competition, prompting the idea that flea species partition temperature, along with correlated variables such as moisture (thermal-niche partitioning hypothesis). I compared the fleas of five rodent-flea communities described from the literature for thermal-niche optima by fitting non-linear LRF (Lobry-Rosso-Flandrois) curves to examine whether flea species in a community show distinct, partitioned thermal niches. LRF curves estimate physiological parameters of temperature minimum, optimum, maximum, and maximum abundance, and facilitate comparison between species by summarizing seasonal data. Flea-communities were on Nearctic Southern flying squirrel (Glaucomys volans volans), Richardson's ground-squirrel (Urocitellus richardsonii), North American deer-mouse (Peromyscus maniculatus), and Palearctic Midday jird (Meriones meridianus), and Wagner's gerbil (Dipodillus dasyurus). Flea communities appeared to show seasonality consistent with thermal-niche partitioning. Several flea families and genera had characteristic thermal niches: Ceratophyllidae had broad tolerance to extreme temperature, Leptopsyllidae (one species in this study) to cold, and Pulicidae to hot. In contrast, at the local, species level, climatic speciation could be significant in flea diversification. Non-competition hypotheses (environmental filtering, neutrality) require testing, too. Thermal-niche partitioning may increase flea species richness on hosts and could occur in other insect and plant communities. Implications for biodiversity conservation and disease ecology under global warming are wide-ranging.

The Southern Flying Squirrel (Glaucomys volans) in Lincoln, Nebraska

The southern flying squirrel (Glaucomys volans) is considered a species of greatest conservation need in Nebraska and listed as threatened in the state. Historically, the geographic range of the southern flying squirrel in Nebraska has been restricted to five eastern counties from a northern suburb of Omaha, Douglas Co., southward in the four counties of Sarpy, Otoe, Nemaha, and Richardson, all bordering the Missouri River on the east. In late November of 2018, a resident of Lincoln, Lancaster Co., Nebraska, contacted the Nebraska Game and Parks Commission about an animal found dead in his yard. This animal proved to be a southern flying squirrel, which was 50 to 70 miles [80 to112 km] west of the known geographic range of the species. Two additional individuals were subsequently observed at the original residence as were individuals in at least a total of 10 neighborhoods throughout the city of Lincoln. Clearly, a population of the southern flying squirrels is established and reproducing in Lincoln, but their origin is unknown. The source of this city-dwelling population may be from released/escaped pets, a natural dispersal from the Missouri River via the Platte River and Salt Creek, or inadvertent translocation when moving timber or fire wood.

Winter Observations of Cavity-Nesting Birds Mobbing Southern Flying Squirrels

I observed mobbing of Glaucomys volans (Southern Flying Squirrel), upon removal and release from nesting boxes designed for them, by various bird species (1–9 total individual birds) on 33 occasions during winter surveys for the squirrels in southeast Ohio. I observed instances of mobbing by 1–3 species of primary and/or secondary cavity-nesting songbirds and woodpeckers. Mobbing behavior included flights within 1–2 m of a flying squirrel briefly positioned on a tree trunk as well as vocalizations. Mobbing episodes lasted 5–180 seconds, which largely depended on the amount of time a flying squirrel remained visible before retreating into a natural cavity. In light of the mobbing response reported here, perhaps more consideration should be given to the potential impacts that Southern Flying Squirrels may have on bird communities.

Drivers of Southern Flying Squirrel (Glaucomys volans) Aggregation Size in South Carolina, U.S.A.

Although it is known that southern flying squirrels (Glaucomys volans) nest in larger groups to offset the energetic costs of low temperatures, the influence of other variables on aggregation size remains relatively unknown. Therefore, the influence of environmental variables and individual characteristics of G. volans on nest box aggregation size was studied from 1992–1998 at the Savannah River Site in South Carolina. Over the study period, 5859 occupied boxes were observed, representing 11,238 captures and 2671 unique individuals. The majority of occupied boxes (60.3%) contained solitary individuals, while 26.1% contained aggregations (≥2 individuals) of adult and/or subadult individuals and 13.6% contained litters. Although ambient temperature is widely believed to be the most important variable influencing aggregation size of G. volans, the final model explaining nest aggregation size for G. volans included not only minimum daily ambient temperature, but also Julian date and individual G. volans characteristics of sex, age, and reproductive status. Minimum ambient temperature was inversely related to aggregation size, with larger aggregation sizes associated with winter months, although aggregation size sharply increased between the months of Aug.–Sept. The retention of Julian date in the final model, in addition to minimum ambient temperature, indicates that behavioral shifts due to seasonal changes, independent of temperature, should be considered. Nestlings were associated with larger aggregation sizes, as were inactive and lactating females and inactive males. However, sex alone did not significantly contribute to the final model. This study demonstrates that in addition to temperature, there are a suite of predictors of nest aggregation size for G. volans that should be considered when evaluating nest box occupancy for this species.

Detection of Porphyrins in Hair Using Capillary Liquid Chromatography-Mass Spectrometry.

Unlike humans, some animals have evolved a physiological ability to deposit porphyrins, which are pigments produced during heme synthesis in cells, in the skin and associated integument such as hair. Given the inert nature and easiness of collection of hair, animals that present porphyrin-based pigmentation constitute unique models for porphyrin analysis in biological samples. Here we present the development of a simple, rapid, and efficient analytical method for four natural porphyrins (uroporphyrin I, coproporphyrin I, coproporphyrin III and protoporphyrin IX) in the Southern flying squirrel Glaucomys volans, a mammal with hair that fluoresces and that we suspected has porphyrin-based pigmentation. The method is based on capillary liquid chromatography-mass spectrometry (CLC-MS), after an extraction procedure with formic acid and acetonitrile. The resulting limits of detection (LOD) and quantification (LOQ) were 0.006–0.199 and 0.021–0.665 µg mL−1, respectively. This approach enabled us to quantify porphyrins in flying squirrel hairs at concentrations of 3.6–353.2 µg g−1 with 86.4–98.6% extraction yields. This method provides higher simplicity, precision, selectivity, and sensitivity than other methods used to date, presenting the potential to become the standard technique for porphyrin analysis.

Exposure to fire affects acorn removal by altering consumer preference

Prescribed fire has been encouraged as a management tool to increase oak regeneration across the southeastern United States. The least utilized part of the burn window in this region is during fall, but burning in this season with the objective of oak regeneration has been discouraged because of the potential negative consequences on subsequent germination. While exposure to fire decreases acorn viability, acorns cached in recently burned areas increases their survival. By following the fate of unburned acorns added to those areas, previous studies identified post-fire habitat characteristics (e.g., altering vegetation structure, decreased leaf litter, etc.) as a cause of increased acorn establishment success. However, exposing acorns to fire may also contribute to fate of surviving acorns by changing consumer removal rates. We exposed acorns to fire and established cafeteria-style experiments in unburned forests to compare burned and unburned acorn selection and removal rate of eight oak species by caching and non-caching consumers (i.e., predator type). Exposing acorns to fire did not appear to affect selection of oak species but affected overall removal risk for acorns differently by species of consumers. For example, while one important non-caching consumer (white-tailed deer, Odocoileus virginianus) and caching consumer (southern flying squirrel, Glaucomys Volans) showed strong selection of burned acorns, other important consumers in each predator type showed little discrimination or strong selection of unburned acorns (e.g., southern fox squirrel Sciurus niger). Exposure to fire reduced the overall rate of removal of acorns and when an acorn was removed, fire significantly reduced the probability that it would be removed by a caching consumer. Overall, our experiment demonstrates that shifts in consumer removal for exposed acorns may play an important role in the net effects of fall burning on oak regeneration.

A de novo genome assembly and annotation of the southern flying squirrel (Glaucomys volans).

Northern (Glaucomys sabrinus) and southern (Glaucomys volans) flying squirrels are widespread species distributed across North America. Northern flying squirrels are common inhabitants of the boreal forest, also occurring in coniferous forest remnants farther south, whereas the southern flying squirrel range is centered in eastern temperate woodlands. These two flying squirrel species exhibit a hybrid zone across a latitudinal gradient in an area of recent secondary contact. Glaucomys hybrid offspring are viable and can successfully backcross with either parental species, however, the fitness implications of such events are currently unknown. Some populations of G. sabrinus are endangered, and thus, interspecific hybridization is a key conservation concern in flying squirrels. To provide a resource for future studies to evaluate hybridization and possible introgression, we sequenced and assembled a de novo long-read genome from a G. volans individual sampled in southern Ontario, Canada, while four short-read genomes (two G. sabrinus and two G. volans, all from Ontario) were resequenced on Illumina platforms. The final genome assembly consisted of approximately 2.40 Gb with a scaffold N50 of 455.26 Kb. Benchmarking Universal Single-Copy Orthologs reconstructed 3,742 (91.2%) complete mammalian genes and genome annotation using RNA-Seq identified the locations of 19,124 protein-coding genes. The four short-read individuals were aligned to our reference genome to investigate the demographic history of the two species. A principal component analysis clearly separated resequenced individuals, while inferring population size history using the Pairwise Sequentially Markovian Coalescent model noted an approximate species split 1 million years ago, and a single, possibly recently introgressed individual.

Winter nest trees of sympatric northern (Glaucomys sabrinus) and southern (Glaucomys volans) flying squirrels: a test of reinforcement in a hybrid zone

Shifting range boundaries can lead to secondary contact of closely related species, which might in turn lead to hybridization when the evolution of reproductive isolation is incomplete. We examined winter nest use of northern (Glaucomys sabrinus (Shaw, 1801)) and southern (Glaucomys volans (Linnaeus, 1758)) flying squirrels in an area of recent secondary contact and known hybridization in Ontario, Canada, to test for evidence of reinforcement due to different and diverging nesting behaviours. We radio-collared 26 flying squirrels (12 G. sabrinus and 14 G. volans) between two survey periods (winters of 2008–2009 and 2019–2020) and identified all nest trees used by individuals throughout each winter. For each nest tree, we identified the nest type and collected tree classification information to compare differences in nest use between species. We also present a novel application of habitat suitability modelling to test for evidence of divergence in nest use through time, which would suggest reinforcement. We found southern flying squirrels used a higher proportion of cavities in large, hardwood trees, whereas northern flying squirrels used more external nests and softwood trees. Conditional probabilities provided some evidence for increased differentiation in nest use by flying squirrels through time. Overall, we found relatively little overlap in winter nest use between flying squirrel species, despite evidence for hybridization at this site, and some weak evidence for increased divergence between species in nest use over 11 years.

Rodent population and community responses to experimental, large scale, long-term coarse woody debris manipulations

Coarse woody debris (CWD) is a structural feature in forests throughout the United States that provides unique cover, runways, and microclimate for various wildlife species. While use and selection of CWD for rodent foraging, travel, and nesting, which can impact an individual’s fitness, has been demonstrated across numerous studies, the role of CWD presence and abundance in rodent population and community dynamics varies across studies. To better understand rodent and CWD relationships, we studied rodent populations across two periods of CWD manipulation in randomly assigned experimental treatments in South Carolina (Period I: March 1996–November 2000; removal of all snags and fallen logs, removal of fallen logs only, and Control, and Period II: January 2002–September 2006; downed woody debris addition, snag addition, and Control). Overall, we found minimal effects of experimental treatments on the rodent community composition and structure, and community level variation was mainly explained by cotton mouse (Peromyscus gossypinus) and southern flying squirrel (Glaucomys volans) captures. There were no experimental treatment effects on captures of cotton mice and southern flying squirrels, but we observed variation across seasons and years. Our study shows that over the long-term, rodent population and community dynamics are not affected by experimental manipulations of CWD in our study area.

High Prevalence of Borrelia mayonii (Spirochaetales: Spirochaetaceae) in Field-Caught Tamias striatus (Rodentia: Sciuridae) From Northern Wisconsin

Borrelia mayonii is a recently discovered bacterial spirochete that causes Lyme disease and is transmitted by the blacklegged tick, Ixodes scapularis Say (Acari: Ixodidae). To date, B. mayonii has been isolated from two vertebrate host species in Minnesota: field-caught white-footed mice (Peromyscus leucopus Rafinesque; Rodentia: Cricetidae) and American red squirrel (Tamiasciurus hudsonicus Erxleben). Here, we describe the first detection of B. mayonii in field-caught eastern chipmunks (Tamias striatus L. (Rodentia: Cricetidae)) from northern Wisconsin. During our study, we captured 530 unique small mammals and found an infection prevalence of 23.50% in field-caught eastern chipmunks (4/17) and 1.19% in Peromyscus spp. (5/420). Mean larval and nymphal burdens were determined for captured Blarina brevicauda (0, 0), Glaucomys volans (0.29, 0.14), Myodes gapperi (0.27, 0), Napaeozapus insignis (0, 0.25), Peromyscus spp. (1.88, 0.11), T. striatus (1.06, 0.65), and Sorex cinereus (0.09, 0). The high B. mayonii infection prevalence in eastern chipmunks suggests that the species may be an important reservoir for B. mayonii in the Upper Midwest.

Ultrasonic Acoustic Surveys of State Endangered Northern Flying Squirrels in the Pocono Mountains, Pennsylvania

AbstractSurveying for flying squirrels by using traditional techniques produces extremely low detection rates compared with ultrasonic acoustics. Within Pennsylvania, the northern flying squirrel subspecies Glaucomys sabrinus macrotis is state listed as endangered due to habitat loss and parasite-mediated competition by and hybridization with the southern flying squirrel Glaucomys volans. This subspecies is isolated from adjacent populations in West Virginia and New York and has experienced drastic population declines. The discovery and characterization of ultrasonic vocalizations of G. s. macrotis and G. volans, as well as successful field surveys with ultrasonic acoustic detectors in the southern Appalachian Mountains, highlight the potential use of this technique for determining the presence of G. s. macrotis. To confirm the feasibility of using this technique on declining populations of G. s. macrotis sympatric with G. volans, we conducted 108 nights of passive ultrasonic acoustic surveys for G. s. macrotis at six survey sites by using two detectors per survey site (N = 12 detectors) in June 2017. We considered sites high quality (“high”) or low quality (“low”) based on the number of physical capture records during the past 2 decades and the dominance of boreo-montane conifer tree species in the overstory. We detected G. s. macrotis at four study sites and G. volans at all six study sites. We found higher average probability of detection for G. s. macrotis in high vs. low sites (0.28 ± 0.06 [mean ± SE] and 0.09 ± 0.07, respectively), whereas probability of detection was similar for G. volans between high and low sites (0.13 ± 0.05 and 0.17 ± 0.05, respectively). We also found G. s. macrotis had lower latency of detection at high vs. low sites (2.7 ± 0.8 and 7.83 ± 1.5 nights, respectively) but G. volans did not vary in latency of detection between sites (5 ± 1.6 and 3.8 ± 1.5 nights, respectively). Our study shows acoustics can be successfully used to efficiently survey G. s. macrotis in Pennsylvania, where populations are small and monitoring these populations more effectively is critical to determining changes in persistence due to climate- and disease-induced factors.

A community-based survey of mammals in the Río Sapo basin, El Salvador

Introduction: El Salvador is one of the most densely populated and most deforested countries of the American continent, where social insecurity make field research difficult. Here we present an experience in which rural and indigenous communities were part of a mammal survey. Objectives: To identify the mammals of Río Sapo basin, and establish the potential of local communities in scientific studies of mammals in El Salvador. Methods: We studied 17 sites in Joateca and Arambala, Río Sapo basin; 14 volunteers were organized, including local former hunters, forest owners, indigenous communities, and researchers. Fieldwork was done from August 2018 to December 2019. Mammals were identified during field visits and with camera traps. We also included the socio-cultural importance of wildlife within the Kakawira-Lenca indigenous worldview. Results: Twenty-two species were identified, including six that are threatened or endangered. We expanded the local range of Tamandua mexicana and Pecari tajacu for the department of Morazán, also, we added Glaucomys volans to the country's species list. We list traditional uses of mammals of the Kakawira-Lenca culture and report the indigenous names of 15 species. Conclusion: The participation of local communities is a valid option for field work in El Salvador, and probably in other areas where social insecurity makes field research dangerous.

Coccidian Parasites of Flying Squirrels, Glaucomys spp. (Rodentia: Sciuridae), from Alaska and Arkansas, with a Description of a New Species of Eimeria (Apicomplexa: Eimeriidae).

New World flying squirrels, Glaucomys spp., are nocturnal arboreal sciurid rodents that have been previously surveyed for coccidial parasites. To date, 4 species of Eimeria have been reported from 2 species of Glaucomys. Here we report 2 species of eimerians from southern flying squirrels (Glaucomys volans) and the endemic Prince of Wales flying squirrel (Glaucomys sabrinus griseifrons). Oocysts of Eimeria dorneyi Levine and Ivens were found to be passing in the feces of 4 G. s. griseifrons from Alaska and a new species of Eimeria was present in feces from 6 G. volans from Arkansas. Oocysts of Eimeria hnidai n. sp. are ellipsoidal with a bilayered wall, measure 23.7 × 13.7 μm, and have a length/width (L/W) ratio of 1.7; a micropyle and oocyst residuum are absent but polar granule(s) are present. Sporocysts are ellipsoidal-elongate and measure 11.8 × 4.9 μm, L/W 2.2; Stieda body is present but sub-Stieda and para-Stieda bodies are absent. The sporocyst residuum is composed of small indistinct granules along the edge or in the center of the sporocyst. This is the first coccidian reported from G. volans from Arkansas as well as the initial coccidian (E. dorneyi) reported from G. s. griseifrons from Alaska. We also provide a summation of the coccidia known from North American flying squirrels.

Movement and Microhabitat Selection in the Southern Flying Squirrel (Glaucomys volans) in Southwestern Illinois

Flying squirrels (genus Glaucomys) have a close association with forest trees for food, shelter, and travel. They play a key role in dispersing seeds and fungi, as well as being an important food source for predators. Thus, understanding their habitat requirements provides insight for conservation efforts, particularly in highly fragmented areas. This study employed radio-telemetry to examine habitat use by Glaucomys volans (Southern Flying Squirrel) in urban and rural fragments in southwestern Illinois. While male home-range sizes were not observed to be significantly different from females, squirrels exhibited significant preference for medium and large trees (>40 cm diameter) over small trees (≤40 cm diameter). Additionally, squirrels selected soft-mast trees for nesting significantly more than expected, with no relationship found between the proportion of hard-mast trees used and home-range size.