Environmental heterogeneity modifies the link between personality and survival in fluctuating small mammal populations

Despite numerous studies examining the fitness consequences of animal personalities, predictions concerning the relationship between personality and survival are not consistent with empirical observations. Theory predicts that individuals who are risky (i.e. bold, active and aggressive) should have higher rates of mortality; however, empirical evidence shows high levels of variation in behaviour-survival relationships in wild populations. We suggest that this mismatch between predictions under theory and empirical observations results from environmental contingencies that drive heterogeneity in selection. This uncertainty may constrain any universal directional relationships between personality traits and survival. Specifically, we hypothesize that spatiotemporal fluctuations in perceived risk that arise from variability in refuge abundance and competitor density alter the relationship between personality traits and survival. In a large-scale manipulative experiment, we trapped four small mammal species in five subsequent years across six forest stands treated with different management practices in Maine, United States. Stands all occur within the same experimental forest but contain varying amounts of refuge and small mammal densities fluctuate over time and space. We quantified the effects of habitat structure and competitor density on the relationship between personality traits and survival to assess whether directional relationships differed depending on environmental contingencies. In the two most abundant species, deer mice and southern red-backed voles, risky behaviours (i.e. higher aggression and boldness) predicted apparent monthly survival probability. Mice that were more aggressive (less docile) had higher survival. Voles that were bolder (less timid) had higher survival, but in the risky forest stands only. Additionally, traits associated with stress coping and de-arousal increased survival probability in both species at high small mammal density but decreased survival at low density. In the two less abundant study species, there was no evidence for an effect of personality traits on survival. Our field experiment provides partial support for our hypothesis: that spatiotemporal fluctuations in refuge abundance and competitor density alter the relationship between personality traits and survival. Our findings also suggest that behaviours associated with stress coping and de-arousal may be subject to density-dependent selection and should be further assessed and incorporated into theory

Predation risk and personality influence seed predation and dispersal by a scatter-hoarding small mammal

Small mammals are key scatter hoarders in forest ecosystems, acting as both seed predators and dispersers. The outcome of their interactions (i.e., predation vs. dispersal) is determined by a series of decisions made by small mammals, such as the choice of seed, whether the seed is immediately consumed or cached, and where it is cached. These decisions are influenced by a variety of factors, including the intrinsic traits of the seed, the individual personality of the scatter hoarder, and the perceived risk of predation while foraging. Furthermore, these factors may all interact to dictate the fate of the seed, with consequences for forest regeneration. Nevertheless, the ways in which perceived predation risk and personality interact to affect the seed dispersal decisions of scatter hoarders are still poorly understood. To contribute in filling this knowledge gap, we tested the hypotheses that southern red-backed voles (Myodes gapperi), an important scatter hoarder in forest ecosystems, would exhibit personality-mediated foraging and that predation risk would alter associations between personality and seed dispersal. We conducted a large-scale field experiment, offering seed trays at stations with altered risk levels and recorded foraging decisions of free-ranging voles with known personalities. We found that personality and perceived predation risk influenced decisions made by foraging voles. Specifically, docility, and boldness predicted foraging site selection, boldness predicted seed species selection and the number of seeds individuals selected, and the tendency to explore of an individual predicted whether voles would remove or consume seeds. Predation risk, mediated by the amount of cover at a site and by moon illumination, affected which foraging site individuals chose, seed species selection, and the probability of removal versus consumption. We did not find support for an interaction between personality and predation risk in predicting foraging decisions. These findings highlight the importance of scatter hoarder personality and perceived predation risk in affecting foraging decisions, with important consequences for seed dispersal and implications for altered patterns of forest regeneration in areas with different small mammal personality distributions or landscapes of fear

Marsupial response to matrix conversion: Results of a large-scale long-term 'natural experiment' in Australia

We quantified changes in forest-dependent mammal populations when the habitat in which they live remains intact but the surrounding matrix is converted from open grazed land to closed pine plantation forest. This situation is increasingly common as plantations are often established on formerly cultivated or grazed land.We conducted a large-scale (30km2), long-term (14years) fully controlled and replicated (111 sites) 'natural experiment' in south-eastern Australia. The study focused on the effects of changes occurring in the matrix on mammals which inhabit patches of native Eucalyptus woodland.We found that none of the five target species in our study (two macropods, two possums and a glider) responded negatively to pine plantation establishment. For three species (the sugar glider Petaurus breviceps, the red necked wallaby Macropus rufogriseus and the swamp wallaby Wallabia bicolor) the response to plantation establishment was positive (i.e., increase in colonisation/patch use in sites surrounded by pine plantations) whereas the two possums (the common ringtail possum Pseudocheirus peregrinus and the common brushtail possum Trichosurus vulpecula) were positively affected by the amount of native tree cover surrounding sites, rather than pine plantation establishment.We foresee two strong implications of our work for the conservation of mammal species in agricultural areas subject to multiple land-use changes: 1) Our results suggest that converting agricultural land to pine plantations will not affect our target mammalian species negatively; rather, it may facilitate colonisation of remnant patches of native vegetation by some species. 2) Our findings underscore the critical importance of preserving remnant native vegetation within plantations, as it may decrease the risk of local extinction for some species or facilitate the colonisation of new sites for others. Thus, retention of patches of remnant native vegetation should be part of the design of future plantations

Forest and snow rather than food or foe limit the distribution of a generalist mesocarnivore in winter

Investigating species responses to trophic interactions and abiotic factors is crucial to better understanding their ecology and creating effective management strategies. In carnivore communities, smaller species are often regulated by larger ones via top-down interference competition. Smaller subordinate carnivores can also be regulated by bottom-up and abiotic factors, such as the availability of important prey, habitat features, and climatic conditions. However, substantial ambiguity remains regarding the relative roles these complex factors play in shaping subordinate carnivore populations, especially during winter. To investigate this issue, we conducted a large-scale camera-trapping study (n = 197 sites distributed across a ~60,000 km2 landscape) using a balanced study design that sampled a gradient of forest disturbance and climatic conditions. We used dynamic occupancy modeling to examine the influences of top-down (interference competition), bottom-up (prey and habitat), and abiotic (climate) factors on a widespread, generalist subordinate carnivore, the red fox (Vulpes vulpes), in Maine, USA. Across three winters, we collected 107 red fox and 185 coyote (Canis latrans) daily detections, and 3875 snowshoe hare (Lepus americanus) detections. We found evidence for the top-down effects of coyotes on red fox detection probability and site colonization. However, contrary to theoretical expectations, the association between coyotes and red foxes was positive rather than negative. Snowshoe hares had a positive association with local extinction by red foxes, which also contrasts with prevailing theory given that snowshoe hares are an important winter prey of red foxes in this ecosystem. The intensity of forest disturbance and the proportion of conifer forest had negative effects on red fox occurrence and detection probability, while snow depth had a strong negative effect on site colonization. Together, these results suggest red foxes are limited more by abiotic and bottom-up factors related to habitat than by the top-down interference competition or primary prey availability in winter. Our study supports recent findings that bottom-up factors may shape carnivore distributions during less productive times of year. Our work also highlights how caution isneeded when extrapolating previous results from summer studies to winter, as the role of top-down and bottom-up factors may change seasonall

Modulation of ecosystem services by animal personalities

Conservationists rarely consider the roles individuals, with their own unique behavior, physiology, and genome, play in shaping ecosystem processes and consequently ecosystem services, but this is changing. An ongoing surge in research on animal personalities (that is, behavioral differences among individuals that are consistent over time and across contexts) is exposing the ecological roles of individuals to scientific scrutiny. Here, we present four broad examples of ecosystem services that are likely to be shaped by personalities: (1) pollination and seed dispersal, (2) regulation of pest species, (3) ecotourism, and (4) maintenance of soil quality. Although researchers have suggested diverse links between animal personality and ecosystem function, very few have examined this association. We outline a four-step process for quantifying and validating these linkages, leading to application for conservation practitioners, and conclude by recommending that accounting for behavioral variation should be incorporated into the management of ecosystem services

The vacant planting: limited influence of habitat restoration on patch colonization patterns by arboreal marsupials in south-eastern Australia

Many key questions remain unresolved about how biodiversity responds to temporal increases in native vegetation cover resulting from extensive restoration efforts. We quantified occupancy and colonization probability of old growth, regrowth and planted woodland patches by arboreal marsupials within Australian agricultural landscapes subject to woodland restoration over an 11 year period. Our analyses focussed on the Common Brushtail Possum (Trichosurus vulpecula) and Common Ringtail Possum (Pseudocheirus peregrinus). We found strong evidence of a gradient in occupancy levels ranging from highest in old growth woodland, approaching zero in plantings, with regrowth woodland intermediate between these two broad types of vegetation structure. Plantings were not occupied by either species at the outset of our investigation and were rarely colonized throughout the subsequent 10 years. We hypothesize that a lack of shelter sites in large old hollow-bearing trees is one of the key factors limiting the occurrence of plantings by cavitydependent arboreal marsupials, suggesting a lag between planting establishment and the time required for plantings to become suitable habitat. We found the probability of colonization was positively related to the amount of vegetation cover in the surrounding landscape. Unexpectedly, colonization probability was not influenced by a temporal increase in woody vegetation cover surrounding a patch. A paucity of relationships between patch colonization and the temporal change in vegetation cover may be explained by the fact that most of the increased vegetation cover in our study landscapes over the past decade has resulted from establishment of plantings which are generally not suitable nesting habitat for arboreal marsupials. Our findings have key management implications such as emphasizing the value of old growth woodland for arboreal marsupials and of targeting restoration efforts around old growth and regrowth woodland patches, and the flawed notion of biodiversity offsets that allow replantings to compensate for clearing old growth woodland.Murray Local land Services, the Riverina Local Land Services, the Australian Research Council, and the Australian Government (National Environmental Science Program)

Differential habitat use between demographic states of black bears in managed timber forests

The long‐term effects of intensive forest harvest on sensitive demographic stages of the American black bear (Ursus americanus) have been often overlooked. Much of Maine, USA, is covered in forests that are hospitable to bears and commercial timber harvest. To investigate the potential effects of differing intensities of disturbance on black bears, and on females with cubs particularly, we designed a large‐scale natural experiment with 197 motion‐sensitive camera sites dispersed over representative forest stands in northern and central Maine. Using multi‐state occupancy models, we distinguished the overall trends in space use by females with young versus adult bears without young. Forest disturbance at large spatial scales was positively associated with the probability of use for both demographic groups and the availability of hardwood trees was an additional important factor for habitat use by females with young. Our study illustrates the use of motion‐sensitive cameras to monitor and understand habitat use by distinct life‐history stages of animals living in human‐modified landscapes, and results indicate that managers can maintain black bear habitat in areas of active forest harvest by ensuring the availability of hardwood specie

Molecular phylogeny of South-East Asian arboreal murine rodents

peer reviewedRecent phylogenetic studies and taxonomic reviews have led to nearly complete resolution of the phylogenetic divisions within the old world rats and mice (Muridae, Murinae). The Micromys division and Pithecheir division are two notable exceptions where groupings of species into these divisions based on morphology and arboreal lifestyle have not been supported by phylogenetic evidence. Several enigmatic species from these divisions have been missing from molecular studies, preventing a rigorous revision of phylogenetic relationships. In this study, we sequenced for the first time one mitochondrial and three nuclear genes from South-East Asian keystone species of these two arboreal divisions: Hapalomys delacouri (Micromys division), Lenothrix canus and Pithecheir parvus (Pithecheir division). We also complemented the molecular data already available for the two divisions with new data from Sundaic Chiropodomys, Indian Vandeleuria oleracea and the recently described Sulawesian Margaretamys christinae. Using this new phylogenetic framework and molecular dating methodologies, our study allows some more detailed classification of the former Micromys and Pithecheir divisions, while confirming their polyphyletic status. Specifically, the former Micromys division should now be split into four monotypic divisions: Chiropodomys, Hapalomys, Micromys and Vandeleuria divisions. The former Pithecheir division is likely to be refined and restricted to Pithecheir and probably Pithecheirops, whereas Lenothrix and Margaretamys should now be recognized as representatives of the Dacnomys division. Our findings have profound implications with regard to the systematics of Murinae, as well as to the early evolution of murine morphology and dental characters

Conserving large mammals on small islands: A case study on one of the world’s most understudied pigs, the Togean islands babirusa

Conserving large mammals on small islands poses a great challenge, given their high resource demand within the limited space available. The endangered Togean Islands babirusa (Babyrousa togeanensis) is one of these species, with a distribution range limited to four small islands in the Togean Archipelago, Indonesia. Despite being listed as endangered, very little information is available on the distribution and ecology of this species. To address this critical knowledge gap, we here report the first field-based ecological study of the Togean Islands babirusa across its entire distribution range. Following a stratified random sampling procedure, we distributed camera traps at 103 stations across four islands to collect data on the species distribution from July-October 2022. We performed an occupancy modeling analysis to assess the species’ habitat use, with various habitat features estimated through remote sensing and field measurements as covariates. We found that forest and mangrove availability over a large area positively influenced babirusa habitat selection. Babirusas only made use of agricultural areas when large forest areas were available nearby. Our results highlight the benefits of redesigning the national park area to accommodate babirusa habitat requirements, specifically by reassigning the non-forested park areas (about 30% of the park area) to non-protected forests currently outside the park boundary (about 50% of total forested area). Our case study exemplifies key challenges associated with conserving large mammals on small islands and highlights the importance of following an adaptive management approach, which in this case implies shifting 30% of the current protected area

Population and individual-scale responses to patch size, isolation and quality in the hazel dormouse

Patch size, isolation and quality are key factors influencing species persistence in fragmented landscapes. However, we still lack a detailed understanding of how these variables exert their effects on populations inhabiting fragmented landscapes. At which ecological scale do they have an effect (e.g., individuals versus populations) and, on which demographic parameters? Answering these questions will identify the mechanisms that underlie population turnover rather than solely predicting it based on proxies (e.g., presence/absence data). We report the results of a large-scale, three-year study focused on the relative effects of patch size, isolation and quality on individuals and populations of an arboreal rodent, the hazel dormouse (Muscardinus avellanarius). We examined 30 sites nested within three landscapes characterized by contrasting levels of habitat amount and habitat quality (food resources). We quantified the effects of patch size and quality on the response of individuals (survival and litter size) and populations (density and colonization/extinction dynamics). We identified demographic mechanisms which led to population turnover. Habitat quality positively affected survival (not litter size) and population density (measured through an index). We infer that the decline in survival due to patch quality reduced patch recolonization rather than increasing extinction, while extinction was mainly affected by patch size. Our findings suggest that the effect of patch quality on individual and population parameters was constrained by the physical structure of the surrounding landscapes. At the same time, our results highlight the importance of preserving habitat quality to help the persistence of entire systems of patches