Associative learning is inversely related to reversal learning in adult Florida scrub-jays and varies with nestling corticosterone exposure Intraspecies differences are cornerstone to natural selection, yet individual differences in cognition in free-living populations have received little attention. Proactive and reactive coping styles describe individual differences in personality and related stress physiology; however, the coping style model can be extended to include predictions regarding measures of cognition. We compared two measures of personality (neophobia and exploratory behaviour) included in the coping style model to cognitive performance on colour-based associative and reversal learning tests in adult Florida scrub-jays, Aphelocoma coerulescens. Also, as exogenous glucocorticoid treatment can affect cognitive performance, we examined whether an individual's naturally occurring physiological phenotype, reflected by corticosterone measures obtained during development and at the time of the learning tests, covaried with learning performance. Performance on associative and reversal learning tests were inversely related. Scrub-jays with low levels of corticosterone as 11 day-old nestlings performed better on an associative learning test as adults, and there was a marginally nonsignificant trend for nestlings with high levels of corticosterone to perform better on a reversal learning test. There was also a marginally nonsignificant trend for neophobic birds to perform better on reversal learning tests. There were no relationships either between adult stress-induced corticosterone levels and learning or exploratory behaviour and learning. Our findings provide evidence that variation in sensitivity to environmental conditions, as reflected by an individual"s coping style, underlie the specific strategy by which individuals perform cognitive tasks (i.e., cognitive style). Florida scrub-jays experience a trade-off in performance between types of learning that covary with early corticosterone exposure.

Plasma glucocorticoid (CORT) levels collected within 3min of capture are commonly believed to reflect pre-stressor, baseline CORT levels. Differences in these "baseline" values are often interpreted as reflecting differences in health, or the amount of social and environmental stress recently experienced by an individual. When interpreting "baseline" values it is generally assumed that any effect of capture-and-handling during the initial sampling period is small enough and consistent enough among individuals to not obscure pre-capture differences in CORT levels. However, plasma CORT increases in less than 3min post-capture in many free-living, endothermic species in which timing has been assessed. In addition, the rate of CORT secretion and the maximum level attained (i.e., the degree of stress-responsiveness) during a severe stressor often differs among individuals of the same species. In Florida scrub-jays (Aphelocoma coerulescens), an individual's stress-responsiveness during a 30min post-capture stressor is correlated with CORT levels in samples collected within 1.5min of capture, suggesting there is an intrinsic connection between stress-responsiveness and pre-capture CORT levels. Although differences in stress-responsiveness accounted for just 11% of the variance in these samples, on average, higher stress-responsive jays (top third of individuals) had baseline values twice that of lower stress-responsive jays (bottom third). Further, plasma CORT levels begin to increase around 2min post-capture in this species, but the rate of increase between 2 and 3min differs markedly with CORT increasing more rapidly in jays with higher stress-responsiveness. Together, these data indicate that baseline CORT values can be influenced by an individual's stress response phenotype and the differences due to stress-responsiveness can be exaggerated during sample collection. In some cases, the effects of differences in stress-responsiveness and the increase in CORT during sample collection could obscure, or supersede, differences in pre-capture plasma CORT levels that are caused by extrinsic factors.

Social learning about mate choices is taxonomically widespread, and is a potentially important mechanism of social evolution that may affect the strength of sexual selection in a population. We used a meta-analytic approach to estimate the effect of mate-choice copying on reproductive decisions. We evaluated effect sizes across 103 experiments from 40 studies that experimentally measured female mate-choice copying in non-human animals representing Arachnida, Insecta, Malacostraca, Aves, and Actinoperygii. Our goals were to quantify the magnitude of the effect of this form of social influence, and the extent to which it is modified by observer experience, model age relative to the observer, attractiveness of prospective mates, and testing conditions (laboratory vs. free-living). Across all studies, females that observed others choosing a male were on average 2.71 times more likely to mate with that male, or with a phenotypically similar individual, compared to females with no social information (odds ratio 95% credible interval: 1.60-4.80). After corrected for publication bias, this effect remained significant (corrected odds ratio: 1.92, 95% credible interval 1.13-3.40). We found little evidence for phylogenetic effects in the occurrence of mate-choice copying. Indeed, studies herein present evidence for mate-choice copying in a broad cross-section of species, but also report exceptions in sister taxa. Social information from observed mate choices of others had a considerably stronger effect on mate choice in free-living subjects than in captive individuals. Inexperienced (virgin) females were more likely to copy mate choices than were experienced females, but the relative age of the model was unrelated to whether copying occurred. Finally, females were more likely to copy the mate choices of others when social information counteracted the observing female's personal or genetic mating preference. We note the need for increased taxonomic representation in tests of mate-choice copying, given the robust demonstration of effects in taxa studied to date. Such broader information will provide additional insight to the drivers of the differences identified here in tendency to copy mate choices of others.

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