The impact of urbanisation on chipmunks, arboreal and flying squirrels: a global systematic review

The current, rapid urbanisation process impacts global biodiversity and can be a driver for phenotypic changes in mammals that persist in cities. Animals display different response strategies in urban environments compared to natural areas, but patterns may differ among species. To better comprehend this process, we focused on a limited number of species that are present in many urban green spaces around the globe.The aim of this systematic review is to investigate which response strategies chipmunks, arboreal and flying squirrels use to cope with urban environments, exploring whether there are general response patterns, and to reveal potential adaptations to life in urban areas. We included studies that compared trait differences among conspecifics living in different areas along an urbanisation gradient (rural-urban) and studies comparing individuals or populations between urban areas with different environmental characteristics.The effects of urbanisation on chipmunks, arboreal and flying squirrels, at the individual and at the population levels, were identified in nine topics. Included articles explored at least one of these topics and their key findings were described.Effects of urbanisation are evident in all considered topics. However, we found contrasting patterns between species or even among individuals of the same species studied in different geographical areas. Overall, we reported two knowledge gaps: some phenotypic traits were considered in few studies, and many species, especially those living in the Global South, where urban growth rate is higher, have not been studied.This systematic review suggests that urbanisation can be an important driver for adaptation in small mammals, underlining the complexity and differentiation of response patterns. Since target species have important ecological and social roles, additional comparative studies, increasing our understanding of processes that determine their presence in cities, are essential for urban green planning which aims to conserve biodiversity

Habitat effects on hoarding plasticity in the Eurasian red squirrel (Sciurus vulgaris).

Hoarding patterns can be classified into two general types: scatter-hoarding and larder-hoarding, but there are intermediate types. Various factors affect hoarding patterns. Animals hoarding identical seeds in different habitats may use different hoarding patterns to adapt to habitat variation. We used a sample-plot investigation method to study cache features and recovery rate of seeds of Arolla pine (Pinus cembra) by Eurasian red squirrels (Sciurus vulgaris) in 2009 and 2010 in two subalpine forests with different tree-species composition in the Italian Alps. Hoarding patterns of red squirrels varied among habitats: the typical scatter-hoarding pattern with most caches including 2-6 seeds is found in spruce (Picea abies) dominated forest, while a combination of few large caches (10 seeds) and many small caches (less than 10 seeds) is found in Arolla pine dominated forest. Consequently, average number of seeds/cache was higher in the latter habitat. Among five microhabitats, shrubs, grass, moss, fallen leaves, and stone, Eurasian red squirrels preferred fallen leaves and moss as hoarding substrate. Cache recovery investigation indicated that recovery rate was 62% in spruce forest and only 21% in Arolla pine forest. A lower availability of suitable hoarding microhabitat resulted in changes in hoarding patterns of red squirrels in Pinus cembra dominated forest. We suggest that the main factor influencing differences in recovery rate was a higher cone production per tree in Pinus cembra forest

Invading parasites: spillover of an alien nematode reduces survival in a native species

It is widely assumed that spillover of alien parasites to native host species severely impacts na\uefve populations, ultimately conferring a competitive advantage to invading hosts that introduced them. Despite such host-switching events occurring in biological invasions, studies demonstrating the impact of alien macroparasites on native animal hosts are surprisingly few. In Europe, native red squirrels (Sciurus vulgaris) are replaced by introduced North American grey squirrels (S. carolinensis) mainly through resource competition, and, only in the United Kingdom and Ireland, by competition mediated by a viral disease. In Italy such disease is absent, but spillover of an introduced North American nematode (Strongyloides robustus) from grey to red squirrels is known to occur. Here, we used long-term (9 years) capture-mark-recapture and parasitological data of red squirrels in areas co-inhabited by grey squirrels in Northern Italy to investigate the impact of this alien helminth on na\uefve native squirrels\u2019 body mass, local survival, and reproduction of females. We found no negative effect of the alien parasite on body mass or reproductive success, but intensity of infection by S. robustus reduced survival of both male and female squirrels. Significantly, survival of squirrels co-infected by their native nematode, Trypanoxyuris sciuri, was less affected by S. robustus, suggesting a protective effect of the native helminth against the new infection. Hence, we demonstrate that alien S. robustus spillover adds to the detrimental effects of resource competition and stress induced by grey squirrels, further reducing the fitness of the native species in the presence of the invasive competitor

Physiological stress and spatio-temporal fluctuations of food abundance and population density in Eurasian red squirrels

In continuously changing environments, variation of different ecological factors could affect the functioning of the hypothalamic-pituitary-adrenal (HPA) axis in wild mammals, increasing the secretion of glucocorticoids (GCs). In different animal species, GC concentrations are often used as a measure of the physiological stress response to environmental pressures, such as fluctuations in food abundance, population density, intra-and interspecific competition, and predation risk. However, previous studies reported contrasting results or did not find clear associations between physiological stress and environmental variables. Here, we used concentrations of faecal glucocorticoid metabolites (FGMs) as an integrated measure of physiological stress in wild Eurasian red squirrels (Sciurus vulgaris) from three study areas in the Italian Alps, to investigate whether variations in conifer-seed crop size and/or population density affected HPA axis activity. Squirrel density was estimated in each trapping session using the minimum number of animals alive, and annual counts of fresh cones from different conifer species were used to estimate annual food abundance (MJ/ha). We expected higher FGMs in response to increasing population density and/or decreasing food abundance, since these two variables could act as environmental stressors. Our results showed a lack of association between population density and FGMs and a significant effect of food abundance on FGMs. When conifer seed-crops were poor to moderate, FGMs increased with food abundance, while in the range of high seed-crops, FGMs remained first constant and then slightly decreased with a further increase in seed abundance. We also found differences in FGMs among seasons, as previously observed in this species. Our study adds further evidence that physiological stress can be influenced in different ways by environmental pressures and that long-term studies using individually marked animals are needed to disentangle the potential adaptive outcome of the physiological stress response in pulsed resource systems

Highly specialized Breast Centers did not experience delay of care during COVID-19 pandemic in Italy: the Senonetwork experience

The study aims to evaluate the performance of selected, high-volume, highly specialized, Italian Breast Centers at the time of COVID-19 pandemic (year 2020), compared to pre-pandemic time (year 2019), highlighting differences in terms of clinical presentation of breast cancer (BC) and therapeutic strategies

The price of being bold: personality affects endoparasite infection in introduced eastern grey squirrels

Animal personality has been defined as consistent between-individual differences in behaviour maintained over time and/or across ecological contexts. Differences in individual personality are measured through traits such as reaction to potential risks or handling novelty, aggressiveness and sociability. Among vertebrates, individual variation in personality has been demonstrated to affect variation in fitness among animals within a population. One of the effects of personality is its potential role in the transmission of parasites and pathogens: risk-taking behavior, exploration tendency, activity and sociality are all traits that may affect hosts\u2019 exposure to parasites by altering contact rates among individuals and/or increasing chances of encountering infective stages in the environment. The aim of the present study was to investigate the relationship between a personality score and the abundance of macroparasites of Eastern grey squirrels (Sciurus carolinensis) as invasive alien species (IAS) introduced in N. Italy. Invasiveness may be enhanced through the process of enemy-release, that is the absence of important predators and/or parasites in the new range compared to the native range. In fact, grey squirrels from populations in Italy have a reduced macroparasite fauna compared to populations in the native range in North America and, as far as endoparasites are concerned, only one intestinal helminth species occurs with high prevalence and intensity in grey squirrels in Italy: Strongyloides robustus. Here we test the hypothesis that bolder squirrels with a high tendency to explore have a higher abundance of S. robustus than more shy, less exploring individuals. We used capture-mark-recapture data gathered over three trapping sessions in 5 high-quality mixed deciduous woods and park in Piedmont to estimate trappability and trap diversity indices (n = 207). Both indices were strongly correlated: therefore a Principal Component Analysis (PCA) was used to derive a new variable (score of the first component, PC1) as single best estimator of tendency of being bold. Next we used PC1 as boldness score in generalized linear models with abundance of S. robustus as dependent variable. We examined 95 grey squirrel carcasses: 61 out of 95 were infected by S. robustus (prevalence 60 \ub1 4%). Abundance varied from 0 to 86 helminths per host (mean \ub1 SE = 6.68 \ub1 1.36) and mean intensity (mI) of S. robustus was 10.4 \ub1 2.0 helminths per host. Only 15 grey squirrels harboured also other helminth species: Trichostrongylus spp. was found in 13 squirrels (13.7%, mean Intensity \ub1 SE: 3.5 \ub1 1.0) and in two hosts we found 6 oxyurid nematodes and 1 specimen of cestode, respectively, but these parasites were not included in the analyses. The first, general model on S. robustus infection showed that endoparasite abundance in grey squirrels increased with both the host\u2019s PC1 score and body mass. However, further models showed that PC1 score only affects squirrels\u2019 infection status, with bolder, more explorative individuals having a higher probability of being infected by S. robustus. Conversely, intensity of infection in infected animals did not vary with PC1 score, but was positively affected by host body mass. There was no significant difference between males and females in either of the infection parameters. Hence, our results supported the first, general prediction that bolder, more explorative animals are more heavily infected by S. robustus than shy grey squirrels. However, we also found that host personality mainly influences the probability of acquiring S. robustus, whereas it has no effect on parasite intensity in already infected hosts, which is instead determined by host body mass

Measuring personality traits in Eurasian red squirrels: A critical comparison of different methods

Animal personality, behavioural differences among individuals which are consistent through time and contexts, is generally described by one or more traits. Different methods are used to measure these traits, such as behavioural observations and trapping indices. Comparing several methods allows to validate different tests and to better identify which aspect of an animal's personality is being measured. Here, we measured activity, exploration and immobility of Eurasian red squirrels (Sciurus vulgaris) using observations from the open field test (OFT), and compared them with trappability and trap-diversity indices calculated from capture–mark–recapture data in six independent study sites. Trappability measures the willingness to enter a baited trap (boldness), while trap-diversity can be a proxy for exploration tendency. Our first aim was to test their repeatability, thus their appropriateness as candidate measures of personality traits. Next, we explored the predictions that (i) trappability, measuring boldness, does not correlate with any of the OFT personality traits, since risk-taking cannot be expressed in our arena test; and (ii) trap-diversity correlates with exploration obtained from the OFT. Considering the species ecology and study design, we used multivariate Bayesian models based on different time intervals (session/year) and habitat types (alpine/plain). We found significant repeatabilities for trappability, for trap-diversity and for most OFT personality traits, except exploration in the plain sites. Independently from habitat type or time interval, trappability did not correlate with either activity, exploration or immobility from OFT, thus measuring a different personality axis, which we considered a proxy for boldness. Trap-diversity did not correlate with exploration from OFT, but seems related to a different aspect of red squirrels' exploration tendency. Our study emphasizes that caution is needed when using behaviours from OFT to measure multiple personality traits and that applying extra methods based on animals’ responses to trapping can provide reliable proxies for boldness and exploration tendency