Heart Rate Telemetry in Geese

With this project proposal we aim at using heart rate telemetry for estimating metabolic costs of individual, free- living greylag geese in an intact social setting. Furthermore, heart rate will serve to judge "fast" individual catecholaminergic responsiveness to (social) stress (SAS: sympathetico-adrenomedullary system). In addition, glucocorticoid responsiveness as a parameter for the "slow" stress axis (PAS: pituitary-adrenocortical system) will be measured non-invasively from faecal samples, by aid of a well established EIA. As heart rate is only an indirect measure of catecholaminergic responsiveness, we (mainly R. Palme et al.) finally aim at developing a non-invasive assay for excreted metabolites of adrenal catecholamines. Greylag geese live in a complex social system. They have a long life span, are long-term monogamous and show female-bonded clan structures. Hence, our free-living, but closely approachable flock is an excellent model system to measure heart rate by implanted transmitters and for simultaneously observing behaviour. A similar transmitter system has been recently applied with Griffon voltures. Hence, hardly any time needs to be spent with developing this technology or adapting it to geese. In a six months test phase, four implanted individuals will serve to establish the work routines. For the following 18 months recording periode, 20 geese (10 males/10 females) shall be implanted with transmitters with a lifetime of 18 months. These transmitters will allow beat-to-beat real time recording parallel to behavioural observations. In addition, 1 min heart rate counts will be stored over the 18 months in a non-volatile memory and will be read out after explantation. Via heart rates, we expect to be able to estimate the metabolic costs of behaviours (in accordance with the greylag ethogram) on an individual base. We hypothesize that behavioural costs and catecholamine as well as glucocorticoid (measured non-invasively from faeces) activation will vary with behaviour, social context, sex, social status and with individual behavioural dispositions ("personality", different styles of coping with environmental/social challenges/stimuli). Thereby, we aim to test hypotheses on the mutual relationship of individual SAS and PAS responses and their relationship with individual behavioural phenotypes. We expect that this approach will allow us to estimate individual costs and benefits of behaviour, of individual strategies to cope with social situations and stressors ("coping styles") and will finally reveal individual differentiation in seasonal and circannual energy budgets. We plan to relate these data with parameters of the pairbond (matching/contrasting coping styles of pair partners, degree of synchrony/supplementation in behaviour, heart rates and hormones) and with reproductive parameters of the individual/pair (egg number and size, hatching and fledging rates). Thereby, we aim at gaining a more comprehensive understanding of individuality (individual behaviour-physiology-interactions) in a social context. In particular, we expect a significant step foreward in our ability to link individual behavioural dispositions, pairbond quality, proximate costs and benefits of social interactions and reproductive effort. In other words, we aim at investigating the proximates of the individual at different social levels, pair and flock, and bridge the gap towards evolutionary consequences/functions.

Humans still think themselves to be unique in their social competence as well as in their cognitive abilities. However, studies in the fields of Socio-and Cognitionbiology in previous years have shown that this is not the case. All vertebrates share similar ancestral brain structures and physiological mechanisms for socio-sexual behaviour, and birds and mammals in particular have developed similar cognitive abilities in the social context. Therefore, it is not surprising that researchers here at the Konrad Lorenz Research Station were able to show similar social structures in Greylag geese, previously thought, to be found only in primates or at least mammalian species. These social structures are, among others, long-term pair relationships, individual recognition, mutual social support in agonistic conflicts, and consolation behaviour. These findings verify that Greylag geese depict a valid model of cognitive and social structures to provide an explanation for the evolution of social organization in primates. The main focus of this FWF-funded project was an attempt to approximate the costs of social life to an individual Greylag goose. To determine these costs we applied three, not mutually exclusive, approaches: 1) Exact time-budgets of individual geese were drawn up, because the time per day spent performing different behaviours or behavioural domains (e.g. social behaviour) are a good estimate for the energy expenditure of individuals (Glucose- and oxygen consumption). Efficiently performing behaviours decreases the time spent feeding and shifts the energy budget. The less energy consumed in the social context, the more energy reserved for growth and reproduction. 2) We related behaviours with excreted stress hormone metabolites. This allows a further approximation of an individual`s energy budget, because glucocorticoids are known to mobilise energy for behaviour. Therefore, individuals should apply their hormonal stress response very economically. 3) Heart rate is known to be a good estimator of glucose consumption. At present 25 free-ranging, socially integrated Greylag geese are implanted with transmitters which allow simultaneous recordings of heart rate and behaviours. In addition, internal data loggers store means of the heart rate means, as well as body core temperature, for eighteen months. Despite a considerable delay in granting the necessary permit for the implantation of these transmitters, we will have extensive data to work with, and expect to produce 17 publications in peer-reviewed journals, one book contribution, twelve invited presentations, 12 additional oral congress contributions, 16 poster presentations, as well a several popular scientific contributions in various media. Our results show that male Greylag geese have to invest up to 50% of their energy expenditure in the social context, that heart rate is modulated to a larger extent by social stimuli than by physical exercise, that watching social interactions of others show tremendous heart rate increases ("bystander effects"), and that `passive social support`, actually dampening the stress hormone reaction in response to social challenges, exists not only in primates, but also in Greylag geese. We assume that the fundamental relationships between an individual`s social embedding and the physiological energetics, which we found in Greylag geese, are basically applicable to all social vertebrates, including humans.