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Abstract Rodents play a key role in forest regeneration by dispersing seeds and interspecific differences in seed preferences could have important consequences for forest growth. The White-footed Mouse (Peromyscus leucopus) and Deer Mouse (Peromyscus maniculatus gracilis) are 2 closely related species that can exploit Red Oak (Quercus rubra) acorns but may display different preference levels due to the high tannin concentration present in these acorns. Here we investigated how White-footed Mice and Deer Mice differ in their ability to exploit Red Oak acorns. We conducted a cafeteria-style experiment where we offered mice (n = 61) acorns of Red Oak and Bur Oak (Q. macrocarpa; control seed with lower tannin levels) and video-recorded their preference and the acorn fate (consumed or cached). Using mixed-effects models, we found that both mouse species selected and consumed Bur Oak acorns at a high rate; however, White-footed Mice were 6.67 times more likely to select and consume Red Oak acorns than Deer Mice. Furthermore, White-footed Mice tended to cache Red Oak acorns near the surface where there is a higher chance of germination, while they usually consumed Bur Oak acorns. Our results suggest that Red Oaks have a better strategy for avoiding predation than Bur Oaks (i.e., high tannin levels leading to caching), and the strong interaction between the White-footed Mouse and Red Oak might be an important mechanism behind the current range expansion of both species in response to climate change. 

Abstract Small mammals such as mice and voles play a fundamental role in the ecosystem service of seed dispersal by caching seeds in small hoards that germinate under beneficial conditions. Pilferage is a critical step in this process in which animals steal seeds from other individuals' caches. Pilferers often recache stolen seeds, which are often pilfered by new individuals, who may recache again, and so on, potentially leading to compounded increased dispersal distance. However, little research has investigated intraspecific differences in pilfering frequency, despite its importance in better understanding the role of behavioural diversity in the valuable ecosystem service of seed dispersal.We conducted a field experiment in Maine (USA) investigating how intraspecific variation, including personality, influences pilferage effectiveness.Within the context of a long‐term capture‐mark‐recapture study, we measured the unique personality of 3311 individual small mammals of 10 species over a 7‐year period. For this experiment, we created artificial caches using eastern white pine (Pinus strobus) seeds monitored with trail cameras and buried antennas for individual identification.Of the 436 caches created, 83.5% were pilfered by 10 species, including deer mice ((Peromyscus maniculatus) and southern red‐backed voles (Myodes gapperi). We show how individuals differ in their ability to pilfer seeds and that these differences are driven by personality, body condition and sex. More exploratory deer mice and those with lower body condition were more likely to locate a cache, and female southern red‐backed voles were more likely than males to locate caches. Also, caches were more likely to be pilfered in areas of higher small mammal abundance.Because the risk of pilferage drives decisions concerning where an animal chooses to store seeds, pilferage pressure is thought to drive the evolution of food‐hoarding behaviour. Our study shows that pilferage ability varies between individuals, meaning that some individuals have a disproportionately strong influence on others' caching decisions and disproportionately contribute to compounded longer‐distance seed dispersal facilitated by pilferage. Our results add to a growing body of knowledge showing that the unique personalities of individual small mammals play a critical role in forest regeneration by impacting seed dispersal. 

Abstract Disease ecologists commonly use abiotic factors (e.g. temperature and moisture) or measures of biodiversity (e.g. species richness) to predict Lyme disease transmission patterns, but variance in infection probability among individuals within a population is poorly understood. Most studies assume intraspecific consistency, but recent evidence suggests that individual traits, such as animal personality, may drive differences in encounter rates with infected vectors and pathogen transmission probabilities through differential space use and microhabitat selection, leading to intraspecific variation in infection probability. In addition, because vectors and hosts are nonrandomly distributed across a landscape, land-use changes that modify key habitat features—such as forest management practices—may substantially alter associations between individual traits and infection probability. To address these gaps in our knowledge, we used a large-scale capture–mark–recapture study targeting Peromyscus mice in Maine, United States, to test whether personality drives probability of Borrelia burgdorferi infection in hosts within managed forest compartments with different silvicultural treatments. Specifically, we tested effects of individual phenotypic traits (physical and behavioral) and environmental traits (microhabitat and forest type) on infection probability within 2 species: P. leucopus and P. maniculatus. We found evidence that boldness negatively influences infection probability in P. maniculatus, and that body mass positively influences infection probability in both species. We found no effect of mouse density, microhabitat, or forest type in our analyses. These results suggest that personalities vary in their functional contributions to the natural cycle of B. burgdorferi, and that broader integration of behavioral diversity in disease ecology studies may aid in identifying key transmission zones for this rapidly expanding vector-borne zoonosis. 

Mutualisms are foundational components of ecosystems with the capacity to generate biodiversity through adaptation and coevolution and give rise to essential services such as pollination and seed dispersal. To understand how mutualistic interactions shape communities and ecosystems, we must identify the mechanisms that underlie their functioning. One mechanism that may drive mutualisms to vary in space and time is the unique behavioral types, or personalities, of the individuals involved. Here, our goal was to examine interindividual variation in the seed dispersal mutualism and identify the role that different personalities play. In a field experiment, we observed individual deer mice ( Peromyscus maniculatus ) with known personality traits predating and dispersing seeds in a natural environment and classified all observed interactions made by individuals as either positive or negative. We then scored mice on a continuum from antagonistic to mutualistic and found that within a population of scatter hoarders, some individuals are more mutualistic than others and that one factor driving this distinction is animal personality. Through this empirical work, we provide a conceptual advancement to the study of mutualism by integrating it with the study of intraspecific behavioral variation. These findings indicate that animal personality is a previously overlooked mechanism generating context dependence in plant–animal interactions and suggest that behavioral diversity may have important consequences for the functioning of mutualisms. 

Abstract 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. 

Understanding factors affecting the functional diversity of ecological communities is an important goal for ecologists and conservationists. Previous work has largely been conducted at the community level; however, recent studies have highlighted the critical importance of considering intraspecific functional diversity (i.e. the functional diversity of phenotypic traits among conspecifics). Further, a major limitation of existing literature on this topic is the lack of empirical studies examining functional diversity of behavioural phenotypes —including animal personalities. This is a major shortcoming because personality traits can affect the fitness of individuals, and the composition of personalities in a population can have important ecological consequences. Our study aims to contribute to filling this knowledge gap by investigating factors affecting the functional diversity of personality traits in wild animal populations. Specifically, we predicted that the richness, divergence and evenness associated with personality traits would be impacted by key components of forest structure and would vary between contrasting forest types. To achieve our objective we conducted a fully replicated large-scale field experiment over a 4 year period using small mammal populations as a model system. We found that greater heterogeneity in the cover of shrubs, coarse woody debris and canopy cover was associated with a greater richness, lower divergence and lower evenness in personality traits. Greater population density was associated with greater functional richness and lower functional divergence and evenness of personality traits. To maintain a behaviourally diverse population and its associated functions, managers may promote heterogeneity in vegetation and increased population density, which we found to be the most important determinants driving functional diversity of personality traits.