Abstract Population differences in behavior can result from experience, which can be drastically different between environments such as urban and rural areas. Urban areas may be more complex, contain more human-made objects but fewer natural objects, or have more non-threatening people. Consequently, animals in urban and rural populations may differ in neophobia levels, what is novel, and attention to human behavior. We conducted two experiments with a common urban bird, the American crow (Corvus brachyrhynchos). On home territories of urban and rural crow family groups, we presented objects that were either equally novel in both environments or more common in one environment than the other. Separately, we measured flight initiation distance (FID) from an approaching person using either a direct or averted, less threatening gaze for individual crows across an urban gradient. We found that urban crows were more neophobic than rural crows, as measured by the probability of feeding near an object that is equally novel in both environments. There were no differences in approach and feeding latencies for the least neophobic family member. Both urban and rural crows were less averse to objects that were more common in their respective environments. In the FID experiment, crows in highly urbanized areas had FIDs 25 m shorter for an indirect gaze, while rural crow FIDs were unaffected by gaze. FIDs were best predicted by crows’ experiences with people in a relatively large area around each trial. These results highlight how experience must be accounted for when considering population differences in behavior.
Abstract Movement between trees is essential for arboreal herbivores in fragmented landscapes, but ground travel can increase energetic costs and predation risk. However, the fine-scale data needed to understand how tree-level decisions shape broader patterns of space use have rarely been available. We combined high-frequency GPS and accelerometry to analyse 92 tree visits from nine free-ranging koalas (Phascolarctos cinereus) monitored over approximately 8-10 days in a fragmented agricultural landscape. We predicted that koala tree use would reflect a balance between the benefits of remaining in a given tree and the costs of moving to another, particularly where movement between trees required ground travel. For each visit, we quantified the temporal dynamics of tree departure, residence time, and within-tree activity in relation to tree size, canopy cover, surrounding tree density, and time of day. Koalas remained in trees about four times longer during the day than at night, were about twice as active during night visits, and were most likely to leave trees before dawn. Koalas also became progressively less likely to leave larger trees as a visit continued, suggesting that larger trees may provide greater value for prolonged occupancy. In contrast, koalas left trees sooner where local tree density was higher, indicating shorter residence times where nearby alternatives were more readily available. In fragmented landscapes, retaining large trees and maintaining locally connected tree cover may therefore help preserve tree-use and movement options for koalas.
Abstract A major goal of behavioral ecology is identifying sources of among-individual variation in behavior. Theory suggests that life history traits and personality should be correlated at the individual level, but despite much attention, it has little support. A potentially crucial aspect influencing life history and personality associations that has been overlooked is sex. Males and females of many species differ in energy requirements, energy allocation, and behavior, suggesting that sex may affect correlations between life history and personality differently; if so, not accounting for sex differences may obscure relationships. We address this possibility by intensive longitudinal sampling of boldness and growth in 66 male and 92 female pillbugs (Armadillidium vulgare) (total N = 158) using novel statistical methods to estimate sex-specific (co-)variances in a single parsimonious model. We found that females and males had similar mean boldness, similar among-individual variation in boldness and in growth rate, but females grew faster than males. We found support for a positive correlation between boldness and growth in males but no correlation in females. Differences in personality–life-history correlations between females and males may be linked to sex-specific reproductive strategies. Given the ubiquity of sex differences in life history and behavior, this sex-specific approach to studying trait integration is likely to provide novel insights in many systems that may have gone unnoticed.
Abstract Although individuals tested in isolation often show substantial behavioral variation, they tend to behave more uniformly in groups, a pattern commonly attributed to social conformity (ie, a form of social learning in which individuals preferentially adopt the most common trait). However, evidence for social conformity in nonhuman animals remains debated, as group-level convergence can also arise from independent learning, where individuals adopt the trait maximizing their fitness. Such learning can generate either adaptive phenotypic convergence or pseudo-conformity when aligning with the group's average strategy provides a selective advantage (eg, by reducing predation risk). The likelihood of these outcomes is shaped by ecological and social factors, yet their relative contributions remain poorly understood, as most studies rely on simplified laboratory conditions. This study explores the conditions under which conformist-like patterns can emerge solely from individual learning, and how costs of deviating from the group strategy and tradeoffs between different selective pressures influence their evolution. I developed an evolutionary model in which individuals sequentially adjust their exploratory behavior through a trial-and-error learning process. At each learning step, an individual explores 2 small behavioral deviations around its current exploration level and retains the variant that yields the highest payoff under the prevailing ecological conditions. The results show that the likelihood of pseudo-conformity depends on the interplay among ecological conditions, group composition and behavioral flexibility, and is particularly favored when predation risk and the energetic costs of escaping predator attacks are high. Moreover, under some conditions, pseudo-conformity may maintain behavioral diversity at the population level by allowing different subgroups to converge on and stabilize around distinct behavioral phenotypes. Overall, these findings underscore that measuring traits in isolation may misrepresent both behavioral variation and evolutionary dynamics.
Abstract Most fear ecology research focusses on daytime escape, yet nighttime escape is also likely to be critical to survival. Current research on fear ecology is predicated on the assumption that escape is the same by day and night, yet recent research alludes to greater complexity in responses. Many prey species are active at night to avoid predators, some predators are nocturnal, and prey likely must rely on a different mix of sensory modalities to detect approaching predators at night. By incorporating thermal imaging technology, we measured alertness, distance to cover and Flight-initiation Distances (FIDs) by day and night, across different predator regimes of European Rabbit Oryctolagus cuniculus, an invasive species in Australia with a long history of coexistence with predators. Distance to cover increased by night, decreased with rabbit alertness, and increased with Starting Distance (SD). The probability of being alert increased closer to cover during day and night. FIDs were longer with longer SDs. Rabbits fled more directly towards cover the further they were from cover at night (but not day) time, and only in the absence of cats and foxes. We demonstrate intense antipredator behavior of rabbits by day and night, and specific nocturnal antipredator adaptations, such as using more open areas and only escaping towards cover where terrestrial nocturnal predators are absent. Given the nuanced changes in antipredator behavior by day and night, our results call for future studies to compare daytime and nighttime behaviors.
