Brigitte M. Weiß

Behavioural and physiological correlates of personality in greylag geese (Anser anser)

Personality means suites of correlated behavioural traits, also referred to as “behavioural syndromes” or “personality dimensions”. Across animal taxa similar combinations of traits seem to prevail, which may have proximate foundation in common neuroendocrine mechanisms. Hitherto, these have been rarely studied in intact social settings. We investigated personalities of greylag goose males from a free-roaming flock that shows complex social relationships. In connection with our longitudinal study on the consistency of behavioural and physiological responses to multiple challenges, we asked whether and how single, personality-related behavioural traits correlate with each other to form personality dimension(s). We tested whether these dimensions were related to physiological characteristics that previously showed limited plasticity (heart rate (HR), baseline and stress-induced excreted immuno-reactive corticosterone (BM), and testosterone metabolites levels) and, furthermore, to age, body measures, and dominance rank. Principal-components analysis based on behavioural variables revealed two factors: 51.1% of variability was explained by “aggressiveness” and a further 19.1% by “sociability”. “Aggressiveness” comprised correlated measures of aggression, subordinance, boldness, vigilance, and proximity to the mate. This “aggressiveness” positively correlated with stress-induced BM levels, the HR increase during aggressive interactions, and with dominance rank, which may suggest proximate and functional contingencies of this personality dimension.

Transitive inference in free-living greylag geese, Anser anser.

Living in large, stable groups is often considered to favour the evolution of cognitive abilities related to social living, such as the ability to track relationships among group members and to make transitive inferences about relationships based on indirect evidence. Greylag geese are relatively small brained, but live in complex societies with social support and clan structures. They form dominance hierarchies in which families dominate pairs and unpaired individuals. However, competition is costly and the ability to transitively infer relationships among flock members may be highly advantageous. We tested five free-living, juvenile greylag geese embedded in a flock of 150 birds for their ability to track multiple dyadic relationships and their transitive inference competence. Individuals were trained on discriminations between successive pairs of five implicitly ordered colours (A–E). All individuals learned to track four dyadic relationships simultaneously and showed transitive inference when presented with nonadjacent colours. Remarkably, the amount of training required was related to the individual’s early social environment. Our study is one of the first to show transitive inference in a precocial bird and suggests an influence of early social experience on sociocognitive abilities. Furthermore, it improves our understanding of social complexity as an important selection pressure for the evolution of cognition.

Grey parrots use inferential reasoning based on acoustic cues alone.

Our ability to make logical inferences is considered as one of the cornerstones of human intelligence, fuelling investigations of reasoning abilities in non-human animals. Yet, the evidence to date is equivocal, with apes as the prime candidates to possess these skills. For instance, in a two-choice task, apes can identify the location of hidden food if it is indicated by a rattling noise caused by the shaking of a baited container. More importantly, they also use the absence of noise during the shaking of the empty container to infer that this container is not baited. However, since the inaugural report of apes solving this task, to the best of our knowledge, no comparable evidence could be found in any other tested species such as monkeys and dogs. Here, we report the first successful and instantaneous solution of the shaking task through logical inference by a non-ape species, the African grey parrot. Surprisingly, the performance of the birds was sensitive to the shaking movement: they were successful with containers shaken horizontally, but not with vertical shaking resembling parrot head-bobbing. Thus, grey parrots seem to possess ape-like cross-modal reasoning skills, but their reliance on these abilities is influenced by low-level interferences.

Isolation and characterization of microsatellite marker loci in the greylag goose (Anser anser)

Ten novel polymorphic microsatellite loci were isolated and characterized from the greylag goose, Anser anser, a long‐term monogamous and biparental bird. Additionally, five new primers pairs were designed based on previously published microsatellite locus sequences from closely related species. Multiplex polymerase chain reactions conditions were optimized for all 15 primer pairs. The number of alleles ranged from two to 12 per locus with an observed heterozygosity ranging from 0.07 to 0.85. This marker set will be used to determine rates and origins of extra‐pair and parasitic young in a population of individually banded greylag geese with known life histories.

Different methods for volatile sampling in mammals

Previous studies showed that olfactory cues are important for mammalian communication. However, many specific compounds that convey information between conspecifics are still unknown. To understand mechanisms and functions of olfactory cues, olfactory signals such as volatile compounds emitted from individuals need to be assessed. Sampling of animals with and without scent glands was typically conducted using cotton swabs rubbed over the skin or fur and analysed by gas chromatography-mass spectrometry (GC-MS). However, this method has various drawbacks, including a high level of contaminations. Thus, we adapted two methods of volatile sampling from other research fields and compared them to sampling with cotton swabs. To do so we assessed the body odor of common marmosets (Callithrix jacchus) using cotton swabs, thermal desorption (TD) tubes and, alternatively, a mobile GC-MS device containing a thermal desorption trap. Overall, TD tubes comprised most compounds (N = 113), with half of those compounds being volatile (N = 52). The mobile GC-MS captured the fewest compounds (N = 35), of which all were volatile. Cotton swabs contained an intermediate number of compounds (N = 55), but very few volatiles (N = 10). Almost all compounds found with the mobile GC-MS were also captured with TD tubes (94%). Hence, we recommend TD tubes for state of the art sampling of body odor of mammals or other vertebrates, particularly for field studies, as they can be easily transported, stored and analysed with high performance instruments in the lab. Nevertheless, cotton swabs capture compounds which still may contribute to the body odor, e.g. after bacterial fermentation, while profiles from mobile GC-MS include only the most abundant volatiles of the body odor.

Sampling the Body Odor of Primates: Cotton Swabs Sample Semivolatiles Rather Than Volatiles

We assessed the suitability of a frequently used sampling method employing cotton swabs for collecting animal body odor for gas chromatography-mass spectrometry (GC-MS) analysis of volatile organic compounds (VOCs). Our method validation showed that both sampling material and sampling protocols affect the outcome of the analyses. Thus, among the tested protocols swabs of pure viscose baked before use and extracted with hexane had the least blank interferences in GC-MS analysis. Most critical for the recovery of VOCs was the handling time: the significant recovery losses of volatiles experienced with this sampling procedure suggest that a rapid processing of such samples is required. In a second part, we used swab sampling to sample the body odor of rhesus macaques (Macaca mulatta), which lack scent glands. First results after GC-MS analysis of the samples collected from these nonhuman primates emphasize that proper analytical performance is an indispensable prerequisite for successful automated data evaluation of the complex GC-MS profiles. Moreover, the retention times and the nature of the identified chemical compounds in our samples suggest that the use of swabs is generally more appropriate for collecting semivolatile rather than VOCs.

A non‐invasive method for sampling the body odour of mammals

Summary 1. Olfaction is a central aspect of mammalian communication, providing information about individual attributes such as identity, sex, group membership or genetic quality. Yet, the chemical underpinnings of olfactory cues remain little understood, one of the reasons being the difficulty in obtaining high quality samples for chemical analysis. 2. In the present study we adjusted and evaluated the use of thermal desorption (TD) tubes, commonly used in plant metabolomic and environmental studies, for non-invasive sampling of mammalian body odour. We obtained chemical profiles of meerkat (Suricata suricatta) body odour samples using TD tubes analysed with gas chromatography – mass spectrometry (GC-MS). 3. TD tubes captured a wide range of volatile and semi-volatile organic compounds including compounds likely originating from the target animals. Adjustment of sampling parameters (distance, volume, flow rate, interruption of sampling) to increase the feasibility for a non-invasive application yielded samples of adequate quality. However, to minimize the variability between samples, sampling parameters should be kept constant and samples should be collected when no conspecifics are close-by. 4. The method was sensitive enough to pick up population differences in the chemical profiles of two captive groups of meerkats, demonstrating its applicability to biological questions. With sufficiently habituated animals, the method is applicable non-invasively, allowing short- and long-term studies on a wide range of questions, including e.g. chemical signatures of kinship, diet, individual health or reproductive state. This article is protected by copyright. All rights reserved.

The importance of the altricial – precocial spectrum for social complexity in mammals and birds: A review

Various types of long-term stable relationships that individuals uphold, including cooperation and competition between group members, define social complexity in vertebrates. Numerous life history, physiological and cognitive traits have been shown to affect, or to be affected by, such social relationships. As such, differences in developmental modes, i.e. the ‘altricial-precocial’ spectrum, may play an important role in understanding the interspecific variation in occurrence of social interactions, but to what extent this is the case is unclear because the role of the developmental mode has not been studied directly in across-species studies of sociality. In other words, although there are studies on the effects of developmental mode on brain size, on the effects of brain size on cognition, and on the effects of cognition on social complexity, there are no studies directly investigating the link between developmental mode and social complexity. This is surprising because developmental differences play a significant role in the evolution of, for example, brain size, which is in turn considered an essential building block with respect to social complexity. Here, we compiled an overview of studies on various aspects of the complexity of social systems in altricial and precocial mammals and birds. Although systematic studies are scarce and do not allow for a quantitative comparison, we show that several forms of social relationships and cognitive abilities occur in species along the entire developmental spectrum. Based on the existing evidence it seems that differences in developmental modes play a minor role in whether or not individuals or species are able to meet the cognitive capabilities and requirements for maintaining complex social relationships. Given the scarcity of comparative studies and potential subtle differences, however, we suggest that future studies should consider developmental differences to determine whether our finding is general or whether some of the vast variation in social complexity across species can be explained by developmental mode. This would allow a more detailed assessment of the relative importance of developmental mode in the evolution of vertebrate social systems.

Familiarity with the experimenter influences the performance of Common ravens (Corvus corax) and Carrion crows (Corvus corone corone) in cognitive tasks.

Highlights • We compared the results of corvids in experiments with familiar/unfamiliar humans.• We investigated behavioural reactions towards familiar and unfamiliar humans.• Corvids performed significantly better in experiments with familiar humans.• Corvids did not show more neophobia towards unfamiliar humans.• Hence, familiarity positively affected the experimental performance of corvids.

The Social Life of Greylag Geese: Patterns, Mechanisms and Evolutionary Function in an Avian Model System

The flock of greylag geese established by Konrad Lorenz in Austria in 1973 has become an influential model animal system and one of the few worldwide with complete life-history data spanning several decades. Based on the unique records of nearly 1000 free-living greylag geese, this is a synthesis of more than 20 years of behavioural research. It provides a comprehensive overview of a complex bird society, placing it in an evolutionary framework and drawing on a range of approaches, including behavioural (personality, aggression, pair bonding and clan formation), physiological, cognitive and genetic. With contributions from leading researchers, the chapters provide valuable insight into historic and recent research on the social behaviour of geese. All aspects of goose and bird sociality are discussed in the context of parallels with mammalian social organisation, making this a fascinating resource for anyone interested in integrative approaches to vertebrate social systems.