Adult male coatis play with a band of juveniles.

This study examined the play behaviour in one group of coatis (Nasua narica) at La Selva Biological Station in Costa Rica. We incidentally found adult males playing with juvenile coatis, and conducted post-hoc analyses to investigate this interaction. Coati groups consist of adult females and juveniles of both sexes until male juveniles reach two years of age and leave the band to become solitary. Adult males only tolerate juveniles for a brief period during breeding season when the males court females to mate. Outside of the breeding season, adult males are known to prey on juveniles. In this study, when adult males were present with the band, play occurred more than was expected by chance, and adult males engaged in many of these play bouts. Because the mechanisms driving infanticidal behaviour are not well understood, and adult male coatis show a range of behaviours from infanticide to highly affiliative interactions with juveniles, using coatis as a model system may elucidate mechanisms underlying infanticide.This research was partially supported by The Evergreen State College Foundation Activity Grant and The Explorers Club Youth Activity Grant.This is the final version of the article. It first appeared from Instituto Internacional de Ecologia via http://dx.doi.org/10.1590/S1519-6984201300020001

Do Nearctic migrant birds compete with residents at army ant raids? A geographic and seasonal analysis

Army ant swarm raids in Neotropical montane forest are attended by diverse flocks of foraging birds that can include residents year-round and overwintering Nearctic migrants. We asked whether migrants and residents affect each other's ability to forage at army ant raids. We quantified variation in raid attendance by three guilds of birds: wintering migrants, regular and obligate raid attending residents (ant-following residents), and facultative raid attending residents. To test whether wintering migrants and residents were negatively associated at raids, we collected data on raid attendance in four adjacent life zones in the Tilarán Mountains of Costa Rica and in different seasons (when migrants were present and absent). We first compared the guilds' raid attendance among life zones. There was little geographic overlap of migrants and ant-following residents at raids, and raid attendance frequencies were strongly correlated with the estimated local abundances of these bird guilds in each life zone. We then analyzed resident bird flock size and species makeup in the life zones where migrants attended raids most often (Premontane and Lower Montane Wet forests). If migrants affected raid attendance by facultative resident birds, we expected resident numbers or species richness at raids to decrease with migrant presence. Resident flock size and species richness did not differ between times of year with and without migrants, and species identities differed little between seasons. Furthermore, resident flock composition in migrant presence season was similar at raids with and without migrants. We conclude migrants had no measurable effect on resident bird army ant exploitation. Migrants were smaller on average and less likely than residents to capture prey from the ground at raids. These body size and foraging substrate differences between residents and migrants may mitigate inter-guild competition for food at raids.Thanks to the Organization for Tropical Studies (OTS) for research support, including assistance in obtaining permits. This project was supported by an ALCOR Fellowship (University of Washington Psychology) and an OTS Post-Course Award to A.K., and University of Washington Royalty Research Fund, National Geographic/Waitt Foundation, and Drexel University start-up grants to S. O'D

Alternative behavioral measures of postconflict affiliation

Animals are known to affiliate after conflicts rather than avoid each other. Affiliation can occur between former opponents or between a former opponent and a third-party, and is more common between individuals with high-quality relationships. We investigate postconflict (PC) affiliation in 3 species of corvid (crows) to examine how both sociality and analysis method influence this behavior. We hypothesized that 1) there will be no former opponent affiliation because the highest-quality relationships in these species are between mates who never fight, therefore eliminating the need to repair this relationship; and 2) colonial rooks and jackdaws will show third-party affiliation with partners, whereas the territorial Eurasian jays will not show this behavior because they lack high-quality relationships outside of the breeding season when their data were collected. PC affiliation is generally analyzed using the latency to first affiliative contact, however this method has limitations. We explore 2 different measures: the frequency and duration of affiliation across each observation session. There was no evidence of former opponent affiliation in rooks or jays, but some in jackdaws according to affiliation durations. Rooks and jackdaws showed third-party affiliation with mates according to affiliation frequencies and durations, and jays showed third-party affiliation according to affiliation durations, but with any individual, not just mates. We suggest that PC affiliation is best investigated using more than first affiliation latencies, and that the frequency and duration of affiliation may indicate whether affiliation is used to address PC stressCJL was supported by the Gates Cambridge Trust and Murray Edwards College. The research was supported by grants from the BBSRC, the Royal Society, and the University of Cambridge. Birds were hand-raised under a Natural England permit, jays were included on the Home Office Project Licence (80/1975) and rooks and jackdaws were kept under a University of Cambridge non-regulated procedures licence. All activities in this study were carried out in accordance with these licences.This is the author accepted manuscript. The final version is available from Oxford University Press via https://doi.org/10.1234/10.1093/beheco/ars14

Rook, But Not Jackdaw, Post-Conflict Third-Party Affiliation Reduces Aggression for Aggressors

Post-conflict (PC) affiliation refers to positive social interactions that occur after fights. Although this behavior has been widely studied, its functions are rarely tested. We examine a potential function of PC third-party affiliation (affiliation between former opponents and bystanders) in rooks and jackdaws by investigating the hypothesis that conflicts lead to further aggression and that PC third-party affiliation increases to reduce such aggression. The results show that PC affiliation reduces PC aggression for rook aggressors who were less likely to receive aggression after conflicts when they were affiliating with another vs. when they were alone. The opposite result was found for victims of both species who received more aggression after conflicts, and this aggression was not reduced by the act of affiliating. Finally, for jackdaw aggressors, the amount of aggression received after conflicts was not influenced by whether the individual was affiliating or alone, indicating that PC third-party affiliation may serve a function that we did not examine. These findings highlight the importance of investigating functional differences in PC affiliative behavior according to the role played in the conflict.We are grateful for financial support from the Gates Cambridge Scholar-ship and Murray Edwards College (CJL), and the BBSRC, the Royal Society, and the University of Cambridge (NSC).This is the author accepted manuscript. The final version is available from Wiley via https://doi.org/10.1111/eth.12078IN

Eurasian jays do not copy the choices of conspecifics, but they do show evidence of stimulus enhancement

Corvids (birds in the crow family) are hypothesised to have a general cognitive tool-kit because they show a wide range of transferrable skills across social, physical and temporal tasks, despite differences in socioecology. However, it is unknown whether relatively asocial corvids differ from social corvids in their use of social information in the context of copying the choices of others, because only one such test has been conducted in a relatively asocial corvid. We investigated whether relatively asocial Eurasian jays ($\textit{Garrulus glandarius}$) use social information (i.e., information made available by others). Previous studies have indicated that jays attend to social context in their caching and mate provisioning behaviour; however, it is unknown whether jays copy the choices of others. We tested the jays in two different tasks varying in difficulty, where social corvid species have demonstrated social information use in both tasks. Firstly, an object-dropping task was conducted requiring objects to be dropped down a tube to release a food reward from a collapsible platform, which corvids can learn through explicit training. Only one rook and one New Caledonian crow have learned the task using social information from a demonstrator. Secondly, we tested the birds on a simple colour discrimination task, which should be easy to solve, because it has been shown that corvids can make colour discriminations. Using the same colour discrimination task in a previous study, all common ravens and carrion crows copied the demonstrator. After observing a conspecific demonstrator, none of the jays solved the object-dropping task, though all jays were subsequently able to learn to solve the task in a non-social situation through explicit training, and jays chose the demonstrated colour at chance levels. Our results suggest that social and relatively asocial corvids differ in social information use, indicating that relatively asocial species may have secondarily lost this ability due to lack of selection pressure from an asocial environment.RM and NSC received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013) / ERC Grant Agreement No. 3399933, awarded to NSC. CJL was funded by the Leverhulme Trust and Isaac Newton Trust with a Leverhulme Early Career Fellowship

Observation of a topologically non-trivial surface state in half-Heusler PtLuSb (001) thin films.

The discovery of topological insulators, materials with bulk band gaps and protected cross-gap surface states in compounds such as Bi2Se3, has generated much interest in identifying topological surface states (TSSs) in other classes of materials. In particular, recent theoretical calculations suggest that TSSs may be found in half-Heusler ternary compounds. If experimentally realizable, this would provide a materials platform for entirely new heterostructure spintronic devices that make use of the structurally identical but electronically varied nature of Heusler compounds. Here we show the presence of a TSS in epitaxially grown thin films of the half-Heusler compound PtLuSb. Spin- and angle-resolved photoemission spectroscopy, complemented by theoretical calculations, reveals a surface state with linear dispersion and a helical tangential spin texture consistent with previous predictions. This experimental verification of topological behaviour is a significant step forward in establishing half-Heusler compounds as a viable material system for future spintronic devices

Endocranial volume is heritable and is associated with longevity and fitness in a wild mammal

Research on relative brain size in mammals suggests that increases in brain size may generate benefits to survival and costs to fecundity: comparative studies of mammals have shown that interspecific differences in relative brain size are positively correlated with longevity and negatively with fecundity. However, as yet, no studies of mammals have investigated whether similar relationships exist within species, nor whether individual differences in brain size within a wild population are heritable. Here we show that, in a wild population of red deer ($\textit{Cervus elaphus}$), relative endocranial volume was heritable (h² = 63%; 95% credible intervals (CI) = 50-76%). In females, it was positively correlated with longevity and lifetime reproductive success, though there was no evidence that it was associated with fecundity. In males, endocranial volume was not related to longevity, lifetime breeding success or fecundity.Leverhulme Trust; Isaac Newton Trust; Natural Environmental Research Council (NE/L00688X/1); European Research Council (grant nos. 250098 and 294494); Australian Research Counci

A diverse diet as an alternative to ryegrass can improve the total antioxidant status of dams at lambing

The objective of this experiment was to determine if providing ewes in the final trimester of pregnancy with choice from diverse diet components would reduce markers of oxidative and metabolic stress in ewes and improve lamb birth weights relative to ewes offered only one forage species, repetitively. Fifty-four, twin bearing Coopworth ewes [initial live weight (LW) = 69.82 ± 1.16 kg] were blocked by weight onto iso-energetic diets with either choice from taxonomically diverse plants [DIV; spatially separated strips of ryegrass (Lolium perenne L.), chicory (Cichorium intybus L.), plantain (Plantago lanceolata L.), red clover (Trifolium pratense L.), and alfalfa (Medicago sativa L.)] or a ryegrass only diet (RYE) for the final third of gestation. The ewes offered the DIV diet birthed 8.9% heavier lambs (5.64 ± 0.20 kg) than RYE ewes (5.18 ± 0.20 kg; P = 0.03). In addition, the DIV ewes had greater (P < 0.01) glutathione peroxidase and total antioxidant status, and lower (P = 0.01) plasma non-esterified fatty acid concentrations than the RYE fed ewes 24 h after lambing. The results indicate that the DIV diet can improve antioxidant status and reduce some markers of oxidative and metabolic stress at lambing compared to a conventional RYE diet

Ingredients for understanding brain and behavioral evolution: Ecology, phylogeny, and mechanism

This is the final version of the article. Available from The Comparative Cognition Society via the DOI in this record.Uncovering the neural correlates and evolutionary drivers of behavioral and cognitive traits has been held back by traditional perspectives on which correlations to look for-in particular, anthropocentric conceptions of cognition and coarse-grained brain measurements. We welcome our colleagues' comments on our overview of the field and their suggestions for how to move forward. Here, we counter, clarify, and extend some points, focusing on the merits of looking for the "best" predictor of cognitive ability, the sources and meaning of "noise," and the ways in which we can deduce and test meaningful conclusions from comparative analyses of complex traits

Beyond brain size: Uncovering the neural correlates of behavioral and cognitive specialization

© Comparative Cognition Society. Despite prolonged interest in comparing brain size and behavioral proxies of "intelligence" across taxa, the adaptive and cognitive significance of brain size variation remains elusive. Central to this problem is the continued focus on hominid cognition as a benchmark and the assumption that behavioral complexity has a simple relationship with brain size. Although comparative studies of brain size have been criticized for not reflecting how evolution actually operates, and for producing spurious, inconsistent results, the causes of these limitations have received little discussion. We show how these issues arise from implicit assumptions about what brain size measures and how it correlates with behavioral and cognitive traits. We explore how inconsistencies can arise through heterogeneity in evolutionary trajectories and selection pressures on neuroanatomy or neurophysiology across taxa. We examine how interference from ecological and life history variables complicates interpretations of brain-behavior correlations and point out how this problem is exacerbated by the limitations of brain and cognitive measures. These considerations, and the diversity of brain morphologies and behavioral capacities, suggest that comparative brain-behavior research can make greater progress by focusing on specific neuroanatomical and behavioral traits within relevant ecological and evolutionary contexts. We suggest that a synergistic combination of the "bottom-up" approach of classical neuroethology and the "top-down" approach of comparative biology/psychology within closely related but behaviorally diverse clades can limit the effects of heterogeneity, interference, and noise. We argue that this shift away from broad-scale analyses of superficial phenotypes will provide deeper, more robust insights into brain evolution