Swarms of swift scavengers: ecological role of marine intertidal hermit crabs in California

This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/s00227-015-2639-3While marine hermit crabs are well known for being omnivorous filter feeders, less is known about the role they may play as active carrion scavengers in intertidal ecosystems. Prior studies have revealed that intertidal hermit crabs can be attracted to chemical cues from predated gastropods. Yet their attraction is usually assumed to be driven primarily by the availability of new shells rather than by food. We conducted field experiments to assess hermit crabs’ potential role as generalist carrion scavengers on the California Coast, examining their speed of attraction and the size of the aggregations they formed in response to chemical cues from freshly smashed gastropods and mussels, both of which indicated available carrion. Compared to all other marine species, hermit crabs (Pagurus samuelis, P. hirsutiusculus, and P. granosimanus) were the fastest to arrive at the provisioning sites. Hermit crabs also dominated the provisioning sites, accumulating in the largest numbers, with aggregations of up to 20 individuals, which outcompeted all other scavengers for carrion. Notably, hermit crabs arrived equally quickly for both smashed gastropod and mussel, even though the latter does not offer suitable shells for hermit crabs and even though the former only yields shell-related chemical cues over time frames longer than our experiments. These results thus suggest that shell availability is not the only, or even the primary, reason marine intertidal hermit crabs aggregate at carrion sites; they also aggregate to forage, thereby playing an important role as active carrion scavengers in intertidal ecosystems.Research was supported by funding from the Miller Institute at Berkeley to M.L

Translating cognitive insights into effective conservation programs: reply to Schakner et al.

This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.tree.2014.09.00

Comparative cognition for conservationists.

Every animal occupies a unique cognitive world based on its sensory capacities, and attentional and learning biases. Behaviour results from the interaction of this cognitive world with the environment. As humans alter environments, cognitive processes ranging from perceptual processes to learned behaviour govern animals' reactions. By harnessing animals' perceptual biases and applying insights from cognitive theory, we can purposefully alter cues to reduce maladaptive responses and shape behaviour. Despite the fundamental connection between cognition and behaviour, the breadth of cognitive theory is underutilised in conservation practice. Bridging these disciplines could augment existing conservation efforts targeting animal behaviour. We outline relevant principles of perception and learning, and develop a step-by-step process for applying aspects of cognition towards specific conservation issues.We would like to thank Nick Davies and several anonymous reviewers for helpful discussions and comments on the manuscript, and Edward Legg and Ljerka Ostojic for feedback on the figures. A.L.G. received generous support from the Gates-Cambridge Trust; A.T. is funded by a BBSRC David Phillips Fellowship (BB/H021817/1); B.P. is funded by a Zukerman Research Fellowship at King's College.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.tree.2014.06.00

Food fights: aggregations of marine hermit crabs (<I>Pagurus samuelis</I>) compete equally for food- and shell-related carrion

This is the author accepted manuscript. The final version is available from Rosenstiel School of Marine & Atmospheric Science at http://dx.doi.org/10.5343/bms.2015.1054.Competition for limiting resources drives animal aggression. Aggression in hermit crabs has been well studied in shell acquisition circumstances, yet less is known about hermit crabs' competitive behavior in other contexts, especially as they relate to feeding. As active foragers, competition for food resources may be a major determinant of hermit crab aggression and fighting behavior, particularly in intertidal marine environments, where protein-rich carrion may be limiting. Here, we measured aggressive, competitive interactions between hermit crabs [Pagurus samuelis (Stimpson, 1857)] that were presented with carrion in the laboratory, immediately after they were collected from the field. Aggregations of three crabs were provided with either mussel or gastropod flesh. Both forms of carrion naturally indicate food availability, though only the latter may correlate with potential shell availability. We found that levels of aggression rose significantly in response to both carrion conditions, but not in response to a control condition involving the introduction of a non-eatable object. Larger individuals displayed the highest levels of aggressive behavior, but levels of aggression did not differ between crabs provided with the gastropod and the mussel flesh. These results reveal that food—independent of a shell resource—can be a powerful motivator for competitive behavior in hermit crabs. Further studies of food-related aggression between different hermit crab species could shed light on how interspecific competition might lead to potential specializations on different carrion or prey resources.Research was supported by funding from the Miller Institute at Berkeley to M.L

Contagious risk taking: social information and context influence wild jackdaws' responses to novelty and risk.

Although wild animals increasingly encounter human-produced food and objects, it is unknown how they learn to discriminate beneficial from dangerous novelty. Since social learning allows animals to capitalize on the risk-taking of others, and avoid endangering themselves, social learning should be used around novel and unpredictable stimuli. However, it is unclear whether animals use social cues equally around all types of novelty and at all times of year. We assessed whether wild, individually marked jackdaws-a highly neophobic, yet adaptable species-are equally influenced by social cues to consume novel, palatable foods and to approach a startling object. We conducted these tests across two seasons, and found that in both seasons observers were more likely to consume novel foods after seeing a demonstrator do so. In contrast, observers only followed the demonstrator in foraging next to the object during breeding season. Throughout the year more birds were wary of consuming novel foods than wary of approaching the object, potentially leading to jackdaws' greater reliance on social information about food. Jackdaws' dynamic social cue usage demonstrates the importance of context in predicting how social information is used around novelty, and potentially indicates the conditions that facilitate animals' adjustment to anthropogenic disturbance.A.L.G. is supported by the generosity of the Gates-Cambridge Trust. A.T. was supported by a BBSRC David Phillips Fellowship (BB/H021817/1).This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/srep2776

Seasonal changes in neophobia and its consistency in rooks: the effect of novelty type and dominance position.

Neophobia, or the fear of novelty, may offer benefits to animals by limiting their exposure to unknown danger, but can also impose costs by preventing the exploration of potential resources. The costs and benefits of neophobia may vary throughout the year if predation pressure, resource distribution or conspecific competition changes seasonally. Despite such variation, neophobia levels are often assumed to be temporally and individually stable. Whether or not neophobia expression changes seasonally and fluctuates equally for all individuals is crucial to understanding the drivers, consequences and plasticity of novelty avoidance. We investigated seasonal differences and individual consistency in the motivation and novelty responses of a captive group of rooks, Corvus frugilegus, a seasonally breeding, colonial species of corvid that is known for being neophobic. We tested the group around novel objects and novel people to determine whether responses generalized across novelty types, and considered whether differences in dominance could influence the social risk of approaching unknown stimuli. We found that the group's level of object neophobia was stable year-round, but individuals were not consistent between seasons, despite being consistent within seasons. In contrast, the group's avoidance of novel people decreased during the breeding season, and individuals were consistent year-round. Additionally, although subordinate birds were more likely to challenge dominants during the breeding season, this social risk taking did not translate to greater novelty approach. Since seasonal variation and individual consistency varied differently towards each novelty type, responses towards novel objects and people seem to be governed by different mechanisms. Such a degree of fluctuation has consequences for other individually consistent behaviours often measured within the nonhuman personality literature.Gates-Cambridge Trust, Biotechnology and Biological Sciences Research Council (Scholarship; David Phillips Fellowship (Grant ID: BB/H021817/1)), University of CambridgeThis is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.anbehav.2016.08.01

Street smart: faster approach towards litter in urban areas by highly neophobic corvids and less fearful birds.

The extent to which animals respond fearfully to novel stimuli may critically influence their ability to survive alongside humans. However, it is unclear whether the fear of novel objects, object neophobia, consistently varies in response to human disturbance. Where variation has been documented, it is unclear whether this variation is due to a change in fear towards specific novel stimuli, or whether it is symptomatic of a general change in fear behaviour. We measured levels of object neophobia in free-flying birds across urban and rural habitats, comparing corvids, a family known for being behaviourally flexible and innovative, with other urban-adapting bird species. Neophobic responses were measured in the presence of different types of objects that varied in their novelty, and were compared to behaviour during a baited control. Corvids were more neophobic than noncorvid species towards all object types, but their hesitancy abated after conspecifics approached in experimental conditions in which objects resembled items they may have experienced previously. Both sets of species were faster to approach objects made from human litter in urban than rural areas, potentially reflecting a category-specific reduction in fear based on experience. These results highlight species similarities in behavioural responses to human-dominated environments despite large differences in baseline neophobia.A.G. received generous support from the Gates-Cambridge Trust. A.T. was supported by a BBSRC David Phillips Fellowship (BB/H021817/1) and a grant from the British Ecological Society.This is the final version of the article. It first appeared from Elsevier via https://doi.org/10.1016/j.anbehav.2016.03.02

Inter-aviary distance and visual access influence conservation breeding outcomes in a territorial, endangered bird

Funding for setting up the housing database was provided by the UK’s Biotechnology and Biological Sciences Research Council (BBSRC; grant BB/G023913/2 to C.R.).Species extinctions are becoming a global crisis, affecting biodiversity and ecosystem services, with island populations being particularly vulnerable. In response, conservation managers are increasingly turning to ex situ conservation breeding programs to establish assurance populations and provide a source for release and re-establishment of wild populations. The 'Alalā (Hawaiian crow, Corvus hawaiiensis) is a critically endangered and territorial island corvid that became extinct in the wild in 2002, following a severe and prolonged population decline during the late 20th century. Surviving individuals of the species were brought into captivity to establish an assurance population to serve as a source for reintroduction, which commenced in 2016. We analyzed the extent to which a range of captive housing conditions impact 'Alalā reproductive success, using 19 years of breeding program data. We found that reproductive success was most strongly affected by the distance between aviaries and their closest neighbors and whether breeding pairs had visual access to other adult conspecifics. Pairs located in aviaries that were more spatially isolated and without visual access to conspecifics were more likely to produce fertile eggs than pairs housed in aviaries that were closer to others or those with visual access to other birds. Our results have direct management implications relevant to the design of conservation breeding centers geared towards the recovery of endangered, territorial bird species. Moreover, since suboptimal housing conditions can increase stress levels in captive birds, our findings are also relevant to improving animal welfare for 'Alalā and other species in conservation breeding programs.PostprintPeer reviewe

Animal Welfare in Conservation Breeding: Applications and Challenges

Animal welfare and conservation breeding have overlapping and compatible goals that are occasionally divergent. Efforts to improve enclosures, provide enriching experiences, and address behavioral and physical needs further the causes of animal welfare in all zoo settings. However, by mitigating stress, increasing behavioral competence, and enhancing reproduction, health, and survival, conservation breeding programs must also focus on preparing animals for release into the wild. Therefore, conservation breeding facilities must strike a balance of promoting high welfare, while minimizing the effects of captivity to increase population sustainability. As part of the Hawaii Endangered Bird Conservation Program, San Diego Zoo Global operates two captive breeding facilities that house a number of endangered Hawaiian bird species. At our facilities we aim to increase captive animal welfare through husbandry, nutrition, behavior-based enrichment, and integrated veterinary practices. These efforts help foster a captive environment that promotes the development of species-typical behaviors. By using the “Opportunities to Thrive” guiding principles, we outline an outcome-based welfare strategy, and detail some of the related management inputs, such as transitioning to parental rearing, and conducting veterinary exams remotely. Throughout we highlight our evidence-based approach for evaluating our practices, by monitoring welfare and the effectiveness of our inputs. Additionally we focus on some of the unique challenges associated with improving welfare in conservation breeding facilitates and outline concrete future steps for improving and evaluating welfare outcomes that also meet conservation goals

Harnessing learning biases is essential for applying social learning in conservation

Social learning can influence how animals respond to anthropogenic changes in the environment, determining whether animals survive novel threats and exploit novel resources or produce maladaptive behaviour and contribute to human-wildlife conflict. Predicting where social learning will occur and manipulating its use are, therefore, important in conservation, but doing so is not straightforward. Learning is an inherently biased process that has been shaped by natural selection to prioritize important information and facilitate its efficient uptake. In this regard, social learning is no different from other learning processes because it too is shaped by perceptual filters, attentional biases and learning constraints that can differ between habitats, species, individuals and contexts. The biases that constrain social learning are not understood well enough to accurately predict whether or not social learning will occur in many situations, which limits the effective use of social learning in conservation practice. Nevertheless, we argue that by tapping into the biases that guide the social transmission of information, the conservation applications of social learning could be improved. We explore the conservation areas where social learning is highly relevant and link them to biases in the cues and contexts that shape social information use. The resulting synthesis highlights many promising areas for collaboration between the fields and stresses the importance of systematic reviews of the evidence surrounding social learning practices.BBSRC David Phillips Fellowship (BB/H021817/1