Small mammal personalities generate context dependence in the seed dispersal mutualism

SignificanceMutualisms are foundational components of ecosystems and give rise to essential services such as seed dispersal and pollination. Ecologists believe that nearly every species is involved in one or more mutualisms, but it is unknown how consistent behavioral differences among individuals, or personalities, may influence an individual's role. We scored individuals on a continuum from antagonistic to mutualistic given their contributions to the seed dispersal mutualism and found that personalities affect the extent to which individuals are mutualistic. These findings suggest a novel mechanism generating context dependence in mutualisms and underscore the need to incorporate behavioral diversity into conservation and restoration efforts

Land-use change alters associations between personality and microhabitat selection

Ecologists commonly assess ecological patterns at the population level, focusing on the average response of all individuals within a population, but to predict how populations will respond to land-use change we must understand how changes to habitat differentially affect individuals within a population. For example, forest management is a widespread type of land-use that impacts wildlife through the loss of key habitat features, but individuals within a population may vary in their responses to this loss due to differences in habitat selection among individuals. Specifically, intraspecific variation in habitat selection has been linked to animal personalities (i.e., consistent behavioral differences among conspecifics), but previous research has not examined whether the relationship between personality and habitat selection is influenced by land-use change. To address this knowledge gap, we tested the hypothesis that land-use change alters the association between personality and microhabitat selection in small mammals. Specifically, we investigated two main questions: (1) To what extent are personality type and microhabitat selection correlated among conspecifics? (2) Does land-use change alter individual patterns of microhabitat selection? To answer these questions, we conducted a large-scale field experiment over 4 years, contrasting unmanaged forest (control) with managed forest (two silvicultural treatments) in Maine, USA. We examined the relationships between habitat selection and personality traits in deer mice (Peromyscus maniculatus) and southern red-backed voles (Myodes gapperi). We found that personality traits were correlated with microhabitat selection at multiple spatial scales. Furthermore, land-use change altered these patterns of selection; resulting in either the loss of personality-associated selection or in novel patterns of selection in managed forests. These findings suggest that promoting structural complexity at multiple spatial scales, such as by interspersing stands of mature forest with managed stands, may maintain a variety of intraspecific habitat selection patterns and the associated ecological outcomes

Effects of forest disturbance, snow depth, and intraguild dynamics on American marten and fisher occupancy in Maine, USA

Human land use is a driving force of habitat loss and modification globally, with consequences for wildlife species. The American marten (Martes americana) and fisher (Pekania pennanti) are forest-dependent carnivores native to North America. Both species suffered population declines due to loss of forested habitat and overharvest for furs, and continued habitat modification is an ongoing threat. Furthermore, the smaller marten may be susceptible to intraguild exclusion where the larger fisher are abundant, and both habitat modification and climate change may reduce spatial refugia available to marten. A detailed understanding of co-occurrence patterns of marten and fisher in landscapes subjected to intense forest disturbance represents a key knowledge gap for wildlife ecology and management. Maine, in the northeastern United States, supports populations of both these species. It is an extensively forested state, and the vast majority is managed as commercial timberland. We designed a large-scale field study to understand the relative importance of three sets of predictions for marten and fisher occupancy patterns where commercial silviculture is widespread: (1) The intensity of forest disturbance primarily determined both marten and fisher occupancy rates, (2) fisher occupancy was limited to areas of shallower snow and marten limited by fisher presence, or (3) both species responded to the composition of tree species within forested habitat. We collected data to test these nonmutually exclusive hypotheses via camera-trap surveys, using an experimental design balanced across a gradient of forest disturbance intensity. We deployed 197 camera stations in both summer and winter over 3 years (2017–2020). We tagged over 800,000 images and found marten at 124 (63%) and fisher at 168 (85%) of the stations. By fitting multiseason occupancy models to the data, we found that the degree of habitat disturbance negatively influenced detection, occupancy, and temporal turnover for both species. Contrary to our expectations, however, we found no evidence of interspecific competition and instead support for positive associations with detection probabilities both spatially and temporally. Both species were positively associated with forest stands containing deciduous trees. Our findings further illustrate the impact that land use has on the occupancy dynamics for these forest-dependent carnivores

Umbrella effect of monitoring protocols for mammals in the Northeast US

Developing cost-effective monitoring protocols is a priority for wildlife conservation agencies worldwide. In particular, developing protocols that cover a wide range of species is highly desirable. Here we applied the ‘umbrella species’ concept to the context of ecological monitoring; specifically testing the hypothesis that protocols developed for the American marten would contextually allow detecting occupancy trends for 13 other mammalian species (i.e., an umbrella effect). We conducted a large-scale four-year camera trapping survey across a gradient of forest disturbance in Maine, USA. We sampled 197 sites using a total of 591 cameras and collected over 800,000 photographs to generate detection histories for the most common terrestrial species. By combining multi-season occupancy modelling and power analyses, we estimated the required sampling effort to detect 10%, 25% and 50% declines in the fourteen species. By conducting a spatially explicit comparison of sampling effort, we found evidence that monitoring protocols for American marten would provide an umbrella effect for up to 11 other mammal species. The capacity of the umbrella effect varied among species, with fisher, snowshoe hare, red squirrel, and black bear consistently covered under several scenarios. Our results support the application of the umbrella species concept to monitoring (here defined as ‘umbrella monitoring species’), providing empirical evidence for its use by management agencies

Seed predation and dispersal by small mammals in a landscape of fear: effects of personality, predation risk and land-use change

Scatter-hoarding small mammals act as both seed predators and seed dispersers in forest ecosystems. Their choices regarding consuming or caching seeds must balance the risk of predation with the energy rewards gained from immediate or delayed consumption of seeds. Several factors influence their interaction with seeds, including the individual's personality. Little is known about how personality affects foraging decisions in response to predation risk. This missing information is critical because if foraging decisions differ among individuals in response to perceived risk, then varying combinations of personality types in a population (and varying risks of predation across forest types) may have diverse effects on forest regeneration. Further, land-use change may influence the interplay of personality, risk perception and foraging decisions by altering the distribution of personality types in the landscape and the risk perceived by individuals. To contribute to filling these knowledge gaps, we designed a large-scale field experiment to evaluate how personality, perceived predation risk and land-use change affect the interaction of deer mice Peromyscus maniculatus and seeds. Using infrared cameras, we recorded the choices of individuals of known personality at paired experimental sites with high versus low perceived predation risk (n = 2389 observations from 74 individuals). We found that personality influenced multiple foraging decisions, and perceived risk affected how individuals with different personalities responded to those decisions. Specifically, exploration/activity influenced seed choice, boldness affected the number of seeds selected and docility influenced both foraging site selection and whether mice immediately consumed or removed seeds. Since personality only affected foraging microsite selection in unmanaged forests, our results show that land-use change decreased the importance of personality in affecting risk perception. We demonstrate the importance of considering personality on foraging decisions under varying levels of risk, and more generally, underscore the importance of considering individual variation in affecting ecological processes

Contrasting effects of pine plantations on two skinks: results from a large-scale ‘natural experiment’ in Australia

The conversion of agricultural land to forest plantations is a major driver of global land-use change, and considering that large portions of the planet are covered by forest plantations, understanding their impact on biodiversity is a research priority. The aim of our study was to quantify the long-term response of two lizard species to the transformation of the matrix surrounding remnant habitat patches (from agricultural land to pine plantations). We used a large-scale (115 sites), long-term (16 years) fully replicated and controlled landscape scale ‘natural experiment’ (the ‘Nanangroe experiment’, Australia) to compare the response of lizard populations to plantation establishment. The study entailed detailed surveys of reptiles in 50 eucalypt patches surrounded by maturing pine Pinus radiata plantations (treatments) and populations inhabiting 55 eucalypt patches surrounded by grazing land (controls). We found that the eastern three-toed earless skink Hemiergis talbingoensis was advantaged by the establishment of the pine plantations (increasing colonization of eucalypt patches embedded within plantations). In contrast, we found that the southern rainbow skink Carlia tetradactyla was negatively affected by surrounding areas of maturing plantations. Thus, our results show that plantations acted as a barrier for one species and increased connectivity for the other. We suggest that leaving areas of land devoid of pines between remnant eucalypt patches may enhance the connectivity for species that respond negatively to plantation establishment while maintaining the beneficial increase in connectivity for others.A.M. is funded by NERP. Funding bodies of the Nanangroe project are Joint Venture Agroforestry Program, NSW Department of Land and Water Conservation, the Australian Research Council, the Kendall Foundation and the Pratt Foundation

The genetic structure and connectivity in two sympatric rodent species with different life histories are similarly affected by land use disturbances

The negative impact of habitat fragmentation due to human activities may be different in different species that co-exist in the same area, with consequences on the development of environmental protection plans. Here we aim at understanding the effects produced by different natural and anthropic landscape features on gene flow patterns in two sympatric species with different specializations, one generalist and one specialist, sampled in the same locations. We collected and genotyped 194 wood mice (generalist species) and 199 bank voles (specialist species) from 15 woodlands in a fragmented landscape characterized by different potential barriers to dispersal. Genetic variation and structure were analyzed in the two species, respectively. Effective migration surfaces, isolation-by-resistance (IBR) analysis, and regression with randomization were used to investigate isolation-by-distance (IBD) and the relative importance of land cover elements on gene flow. We observed similar patterns of heterozygosity and IBD for both species, but the bank vole showed higher genetic differences among geographic areas. The IBR analysis suggests that (i) connectivity is reduced in both species by urban areas but more strongly in the specialist bank vole; (ii) cultivated areas act as dispersal corridors in both species; (iii) woodlands appear to be an important factor in increasing connectivity in the bank vole, and less so in the wood mouse. The difference in dispersal abilities between a generalist and specialist species was reflected in the difference in genetic structure, despite extensive habitat changes due to human activities. The negative effects of fragmentation due to the process of urbanization were, at least partially, mitigated by another human product, i.e., cultivated terrains subdivided by hedgerows, and this was true for both species

Managing uncertainty in movement knowledge for environmental decisions.

Species' movements affect their response to environmental change but movement knowledge is often highly uncertain. We now have well-established methods to integrate movement knowledge into conservation practice but still lack a framework to deal with uncertainty in movement knowledge for environmental decisions. We provide a framework that distinguishes two dimensions of species' movement that are heavily influenced by uncertainty: knowledge about movement and relevance of movement to environmental decisions. Management decisions can be informed by their position in this knowledge-relevance space. We then outline a framework to support decisions around (1) increasing understanding of the relevance of movement knowledge, (2) increasing robustness of decisions to uncertainties and (3) improving knowledge on species' movement. Our decision-support framework provides guidance for managing movement-related uncertainty in systematic conservation planning, agri-environment schemes, habitat restoration and international biodiversity policy. It caters to different resource levels (time and funding) so that species' movement knowledge can be more effectively integrated into environmental decisions

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