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Squirrel Nation is a history of Britain's two species of squirrel over the past two hundred years. The red squirrel, although rare, is among the most cherished of native species. Grey squirrels, by contrast, are one of the most frequently seen wild creatures in our gardens, parks, towns and countryside, and many Britons consider it to be a foreign interloper, introduced from North America in the late nineteenth century. By examining this animal's colonization of Britain, Peter Coates also explores timely issues of belonging, nationalism, citizenship and the defence of borders within Britain today. Ultimately, though people are swift to draw distinctions between British squirrels and squirrels in Britain, Squirrel Nation shows that Britain's two squirrel species have much more in common than at first appears.

We examined temporal (annual and seasonal) patterns of nest box occupancy by red squirrels in a coniferous habitat in Great Britain. The effects of woodland habitat variation, and competition from nesting Great tits were investigated over a nine year period using basic linear models with a binomial error structure. Box use varied seasonally with peaks in the summer and autumn and was positively associated with the abundance of larch. 60 nest boxes yielded nine red squirrel carcasses, and although a small number, the material would be useful in genetic and viral infection studies. Nest boxes were not favoured by breeding female red squirrels and only three litters were found. We highlight the value and limitation of nest boxes as a tool in the applied conservation of red squirrels, and make recommendations for future areas of research on this topic.

Although natal dispersal has received considerable attention from animal ecologists, the causes and consequences of breeding dispersal have remained largely unexplored. We used telemetry, direct observation, and long-term mark-recapture (9 yr) to study breeding dispersal in the North American red squirrel (Tamiasciurus hudsonicus) at Kluane, Yukon, Canada. We recorded the postbreeding behavior (keep the territory, share it with juveniles, or bequeath it to juveniles) of mothers from 485 litters, and monitored the fates of eight cohorts of weaned juveniles (680 individuals). The proportion of mothers that bequeathed their territory to one of their offspring was roughly one-third of that keeping or sharing it. Breeding dispersal was a recurrent phenomenon that characterized a fraction of the population of reproductive females every year. Dispersing females did not improve the quality of their breeding environment. In contrast, by leaving their territory, mothers allowed some offspring to stay on the natal site, which increased juvenile survival. Breeding dispersal by female red squirrels was thus a form of parental investment. Dispersing females were older than others, had higher numbers of juveniles at weaning, and moved their breeding sites more frequently after reproducing when food availability was high. These patterns are consistent with the major predictions of parental investment theories. We detected no difference in survivorship or future reproduction between dispersing and resident mothers. Juvenile males dispersed more often than females, but not farther. The sex of offspring did not influence whether mothers dispersed or not. Although we showed that breeding dispersal can have major impacts on the dynamics of squirrel populations, the relative implications of natal and breeding dispersal for the genetic structure and demography of populations and the social evolution of species remain unknown.

Aim Spatiotemporal variation in resource availability is a strong driver of animal distributions. In the northern hardwood and boreal forests of the northeastern United States, tree mast events provide resource pulses that drive the population dynamics of small mammals, including the American red squirrel (Tamiasciurus hudsonicus), a primary songbird nest predator. This study sought to determine whether mast availability ameliorates their abiotic limits, enabling red squirrel elevational distributions to temporarily expand and negatively impact high‐elevation songbirds. Location Northeastern United States. Methods We used two independent datasets to evaluate our hypotheses. First, we fit a dynamic occupancy model using data from camera trap surveys to evaluate red squirrel distributional responses to pulses in the tree mast. We also assessed population responses using systematic auditory surveys analysed with an open‐population binomial mixture model. Further, we used modelled red squirrel abundance in nest‐survival models to evaluate whether their abundance is correlated with the daily nest survival of three songbird species. Results The tree mast provided a critical resource pulse that resulted in a two‐fold increase in the annual elevational distribution of red squirrels. The elevational distribution of red squirrels ranged from a minimum of ~450 m (range: 663–1145 m asl) following two consecutive years without a masting event to a maximum of over 1000 m (range: 443–1545 m asl) after a large mast event. The daily nest survival of three songbird species tended to decline with an increase in the abundance of red squirrels. Main Conclusions Tree mast is a central biological phenomenon in many temperate and boreal forests. This study reveals how this resource pulse results in range changes in a small mammal that is both a seed and bird predator, as well as prey for many carnivores. Thus, understanding this phenomenon can inform the conservation and management of northern forests, including breeding songbirds.

Sky islands, ecosystems found on geographically isolated mountain peaks, are among the most biodiverse ecosystems in the world but face a disproportionately high threat from climate change. High‐elevation, montane ecosystems, which are already at their upper altitudinal limits, are predicted to severely contract in response to climate change. The identification and conservation of refugia is an increasingly important approach for protecting biodiversity associated with imperiled ecosystems. We explored the spruce‐fir–northern hardwood ecotone as a possible refugium for mammals in the Southern Appalachian red spruce (Picea rubens)‐Fraser fir (Abies fraseri) sky islands. We conducted livetrapping, camera trapping, and ultrasonic acoustic surveys to characterize mammal diversity across the spruce‐fir–northern hardwood forest gradient on Grandfather Mountain and Roan Mountain Highlands in western North Carolina, USA. We detected four out of the five spruce‐fir‐associated small mammal species in both spruce‐fir and ecotone habitats. Mammal species richness, alpha diversity, and bat activity tended to be higher in the ecotone than in the other forest types on both mountains. Next, the abundance of small mammals associated with spruce‐fir was higher in the spruce‐fir and ecotone forests for one of the three species we were able to estimate. Together, our results suggest that the spruce‐fir–northern hardwood ecotone might serve as refugium for mammal species that are associated with spruce‐fir sky islands in the Southern Appalachian Mountains and mammalian conservation efforts in this biodiversity hotspot should consider focusing on the ecotone in addition to the adjacent spruce‐fir ecosystem. Sky islands are among the most biodiverse ecosystems in the world but face a disproportionately high threat from climate change. We examined the spruce‐fir–northern hardwood ecotone as a possible refugium for mammals in the Southern Appalachian red spruce (Picea rubens)–Fraser fir (Abies fraseri) sky islands. We detected spruce‐fir‐associated small mammal species in both spruce‐fir and ecotone habitats, wherein mammal species richness, alpha diversity, and bat activity tended to be higher in the ecotone than in the other forest types on both mountains. Together, our results suggest that the spruce‐fir–northern hardwood ecotone may serve as a key refugium for mammal species that are associated with spruce‐fir sky islands in the Southern Appalachian Mountains, and mammalian conservation efforts in this biodiversity hotspot should consider focusing on this ecotone in addition to the adjacent spruce‐fir ecosystem.

The Eurasian red squirrel (Sciurus vulgaris) has played an important role in Finnish traditional culture and livelihoods since pre‐historic times. This paper analyzes the current role, status, and trends of the red squirrel using both available scientific evidence and testimonies from oral historians who were immersed in Finland's boreal hunting societies during the mid‐1900s. The convergence of observations points to the decline of this iconic mammal of northern forests and increased migration to urban habitats. Red squirrels are not currently seen as being of great relevance to conservation efforts, despite their central role in spreading seeds and in boreal predator–prey food chains. If the animal is lost from Finland's remaining boreal timber forests, their absence may have consequences that are not yet understood. This article contains previously unavailable cultural knowledge of the Eurasian red squirrel, directly curated by knowledge holders. It presents an important nexus of different ways of knowing. Eurasian red squirrel (Sciurus vulgaris) has played an important role in Finnish traditional culture and livelihoods from pre‐historic times. Convergence of observations points to the case where the iconic mammal of the northern forests is in decline and migrating to the urban habitats, with a number of important consequences. If the animal is lost from the remaining boreal timber forest in Finland, their absence may have consequences that are not yet understood.

Urbanization has important effects on the distribution and persistence of wildlife communities. Urbanization may alter not just the distributions of individual species, but also co-occurrence patterns and thus the potential for interspecific interactions (e.g., competition, predation) that structure wildlife communities. Little is currently known about how urbanization alters species co-occurrence or how these changes shape urban species assemblages. Using tree squirrels as a model functional group, we quantified how urbanization alters species occurrence and co-occurrence patterns to shape species assemblages, and how these effects vary within and among cities. We constructed a multi-species, multi-season occupancy model to identify relationships between tree squirrel occupancy and co-occurrence and local land and tree canopy cover and examined variation in these relationships within and among nine US cities. Species’ responses to canopy cover were highly variable among, but less variable within cities, suggesting that even common urban wildlife species may respond differently to urban intensity in different landscape contexts. Species co-occurrence was also highly variable among cities and weakly related to canopy cover within a city. These findings provide important evidence that both environmental attributes and species interactions shape urban wildlife communities. Important for management and conservation, they suggest that tree-canopy cover can particularly support forest species co-occurrence and that managing urban forests to provide high canopy cover could contribute to the diversity of urban wildlife communities in forested ecoregions.

An animal's home-range can be expected to encompass the resources it requires for surviving or reproducing. Thus, animals inhabiting a heterogeneous landscape, where resource patches vary in size, shape and distribution, will naturally have home-ranges of varied sizes, so that each home-range encompasses a minimum required amount of a resource. Home-range size can be estimated from telemetry data, and often key resources, or proxies for them such as the areas of important habitat types, can be mapped. We propose a new method, Resource-Area-Dependence Analysis (RADA), which uses a sample of tracked animals and a categorical map to i) infer in which map categories important resources are accessible, ii) within which home range cores they are found, and iii) estimate the mean minimum areas of these map categories required for such resource provision. We provide three examples of applying RADA to datasets of radio-tracked animals from southern England: 15 red squirrels Sciurus vulgaris, 17 gray squirrels S. carolinensis and 114 common buzzards Buteo buteo. The analyses showed that each red squirrel required a mean (95% CL) of 0.48 ha (0.24--0.97) of pine wood within the outermost home-range, each gray squirrel needed 0.34 ha (0.11-1.12) ha of mature deciduous woodland and 0.035-0.046 ha of wheat, also within the outermost home-range, while each buzzard required 0.54 ha (0.35-0.82) of rough ground close to the home-range center and 14 ha (11-17) of meadow within an intermediate core, with 52% of them also relying on 0.41 ha (0.29-0.59) of suburban land near the home-range center. RADA thus provides a useful tool to infer key animal resource requirements during studies of animal movement and habitat use.

Individuals often interact more closely with some members of the population (e.g., offspring, siblings, or group members) than they do with other individuals. This structuring of interactions can lead to multilevel natural selection, where traits expressed at the group-level influence fitness alongside individual-level traits. Such multilevel selection can alter evolutionary trajectories, yet is rarely quantified in the wild, especially for species that do not interact in clearly demarcated groups. We quantified multilevel natural selection on two traits, postnatal growth rate and birth date, in a population of North American red squirrels (Tamiasciurus hudsonicus). The strongest level of selection was typically within-acoustic social neighborhoods (within 130 m of the nest), where growing faster and being born earlier than nearby litters was key, while selection on growth rate was also apparent both withinlitters and within-study areas. Higher population densities increased the strength of selection for earlier breeding, but did not influence selection on growth rates. Females experienced especially strong selection on growth rate at the within-litter level, possibly linked to the biased bequeathal of the maternal territory to daughters. Our results demonstrate the importance of considering multilevel and sex-specific selection in wild species, including those that are territorial and sexually monomorphic.

Juvenile survival to first breeding is a key life‐history stage for all taxa. Survival through this period can be particularly challenging when it coincides with harsh environmental conditions such as a winter climate or food scarcity, leading to highly variable cohort survival. However, the small size and dispersive nature of juveniles generally make studying their survival more difficult. In territorial species, a key life‐history event is the acquisition of a territory. A territory is expected to enhance survival, but how it does so is not often identified. We tested how the timing of territory acquisition influenced the winter survival of juvenile North American red squirrels Tamiasciurus hudsonicus, hereafter red squirrels, and how the timing of this event mediated the sources of mortality. We hypothesized that securing a territory prior to when food resources become available would reduce juvenile susceptibility to predation and climatic factors overwinter. Using 27 years of data on the survival of individually marked juvenile red squirrels, we tested how the timing of territory acquisition influenced survival, whether the population density of red squirrel predators and mean temperature overwinter were related to individual survival probability, and if territory ownership mediated these effects. Juvenile red squirrel survival was lower in the years of high predator abundance and in colder winters. Autumn territory owners were less susceptible to lynx Lynx canadensis and possibly mustelid Mustela and Martes spp., predation. Autumn territory owners had lower survival in colder winters, but surprisingly non‐owners had higher survival in cold winters. Our results show how the timing of a life‐history event like territory acquisition can directly affect survival and also mediate the effects of biotic and abiotic factors later in life. This engenders a better understanding of the fitness consequences of the timing of key life‐history events. The authors examine how territories, predators and climate influenced the winter survival of juvenile North American red squirrels over three decades. Territory owners survived better and were less affected by lynx abundance, but territories did not improve survival over colder winters. They provide insights into the understudied life stage of first independence.