Measuring individual identity information in animal signals: Overview and performance of available identity metrics

Identity signals have been studied for over 50 years but, and somewhat remarkably, there is no consensus as to how to quantify individuality in animal signals. While there is a variety of different metrics to quantify individuality, these methods remain un‐validated and the relationships between them unclear. We contrasted three univariate and four multivariate identity metrics (and their different computational variants) and evaluated their performance on simulated and empirical datasets. Of the metrics examined, Beecher's information statistic (HS) performed closest to theoretical expectations and requirements for an ideal identity metric. It could be also easily and reliably converted into the commonly used discrimination score (and vice versa). Although Beecher's information statistic is not entirely independent of study sampling, this problem can be considerably lessened by reducing the number of parameters or by increasing the number of individuals in the analysis. Because it is easily calculated, has superior performance, can be used to quantify identity information in single variable or in a complete signal and because it indicates the number of individuals who can be discriminated given a set of measurements, we recommend that individuality should be quantified using Beecher's information statistic in future studies. Consistent use of Beecher's information statistic could enable meaningful comparisons and integration of results across different studies of individual identity signals.Grant NCN 2015/19/P/NZ8/0250

General Principles for the Welfare of Animals in Production Systems: The Underlying Science and Its Application

In 2012, the World Organisation for Animal Health adopted 10 ‘General Principles for the Welfare of Animals in Livestock Production Systems’ to guide the development of animal welfare standards. The General Principles draw on half a century of scientific research relevant to animal welfare: (1) how genetic selection affects animal health, behaviour and temperament; (2) how the environment influences injuries and the transmission of diseases and parasites; (3) how the environment affects resting, movement and the performance of natural behaviour; (4) the management of groups to minimize conflict and allow positive social contact; (5) the effects of air quality, temperature and humidity on animal health and comfort; (6) ensuring access to feed and water suited to the animals’ needs and adaptations; (7) prevention and control of diseases and parasites, with humane euthanasia if treatment is not feasible or recovery is unlikely; (8) prevention and management of pain; (9) creation of positive human–animal relationships; and (10) ensuring adequate skill and knowledge among animal handlers. Research directed at animal welfare, drawing on animal behaviour, stress physiology, veterinary epidemiology and other fields, complements more established fields of animal and veterinary science and helps to create a more comprehensive scientific basis for animal care and management

Classification of pig calls produced from birth to slaughter according to their emotional valence and context of production

Vocal expression of emotions has been observed across species and could provide a non-invasive and reliable means to assess animal emotions. We investigated if pig vocal indicators of emotions revealed in previous studies are valid across call types and contexts, and could potentially be used to develop an automated emotion monitoring tool. We performed an analysis of an extensive and unique dataset of low (LF) and high frequency (HF) calls emitted by pigs across numerous commercial contexts from birth to slaughter (7414 calls from 411 pigs). Our results revealed that the valence attributed to the contexts of production (positive versus negative) affected all investigated parameters in both LF and HF. Similarly, the context category affected all parameters. We then tested two different automated methods for call classification; a neural network revealed much higher classification accuracy compared to a permuted discriminant function analysis (pDFA), both for the valence (neural network: 91.5%; pDFA analysis weighted average across LF and HF (cross-classified): 61.7% with a chance level at 50.5%) and context (neural network: 81.5%; pDFA analysis weighted average across LF and HF (cross-classified): 19.4% with a chance level at 14.3%). These results suggest that an automated recognition system can be developed to monitor pig welfare on-farm.publishedVersio

Expression of emotional arousal in two different piglet call types

Humans as well as many animal species reveal their emotional state in their voice. Vocal features show strikingly similar correlation patterns with emotional states across mammalian species, suggesting that the vocal expression of emotion follows highly conserved signalling rules. To fully understand the principles of emotional signalling in mammals it is, however, necessary to also account for any inconsistencies in the way that they are acoustically encoded. Here we investigate whether the expression of emotions differs between call types produced by the same species. We compare the acoustic structure of two common piglet calls—the scream (a distress call) and the grunt (a contact call)—across three levels of arousal in a negative situation. We find that while the central frequency of calls increases with arousal in both call types, the amplitude and tonal quality (harmonic-to-noise ratio) show contrasting patterns: as arousal increased, the intensity also increased in screams, but not in grunts, while the harmonicity increased in screams but decreased in grunts. Our results suggest that the expression of arousal depends on the function and acoustic specificity of the call type. The fact that more vocal features varied with arousal in scream calls than in grunts is consistent with the idea that distress calls have evolved to convey information about emotional arousal

The Joint Log-Lift Task: A Social Foraging Paradigm

Behavioural cooperation is under intense research. Yet, popular experimental paradigms often employ artificial tasks, require training, or do not permit partner choice, possibly limiting their biological relevance. We developed the joint log-lift task, a social foraging paradigm in which animals have to jointly lift a log to each obtain a food reward. The task relies on an obligate strategy, meaning that the only way to benefit is to work jointly. We hypothesised that (1) animals learn to spontaneously solve the task, and that (2) kin and (3) more sociable individuals would engage more often together in the task and achieve greater success than non-kin and less sociable individuals, respectively. We presented the task to 8 groups of juvenile domestic pigs (Sus scrofa domesticus) in their home pen for 30 min daily. Over the course of 9 days, the pigs showed evidence of learning by progressively switching from individual to joint behaviours, leading to 68% (62 out of 91 pigs) spontaneously solving the task. Success was influenced by sociability, but not kinship. There were large differences in success among dyads, hinting at the possible role of social dynamics and inter-individual differences in the ability and/or motivation to solve the task. The joint log-lift task allows researchers to investigate spontaneous cooperative tendencies of individuals, dyads and groups in the home environment through ad libitum engagement with the apparatus. This ecologically relevant paradigm opens the way to investigate social foraging experimentally at large scale, by giving animals free choice about when and with whom to work jointly

Animal play and animal welfare

Play has long been identified as a potential welfare indicator because it often disappears when animals are under fitness challenge and because it is thought to be accompanied by a pleasurable emotional experience. But animal play is a vexing behavioural phenomenon, characteristically flexible and variable within and between species, with its proximate mechanisms and ultimate functions still not fully understood. Its relationship to animal welfare is therefore complex and merits a focused theoretical investigation. We review evidence on four aspects of the play–welfare relationship: first, that play indicates the absence of fitness threats; second, that play acts as a reward and flags up the presence of opioid-mediated pleasurable emotional experiences; third, that play brings immediate psychological benefits and long-term fitness and health benefits, and thus improves current and future welfare; and finally, that play is socially contagious and therefore capable of spreading good welfare in groups. On this basis, we argue that play does indeed hold promise as a welfare indicator and also as a tool to improve it; but we also point to difficulties in its study and interpretation, and identify some unresolved questions. As a welfare indicator, play may signal both the absence of bad welfare and the presence of good welfare, thus covering a wide range of the welfare spectrum. However, play can also increase in stressful situations, in response to reduced parental care, or as a rebound after a period of deprivation and therefore does not consistently reflect favourable environmental conditions. A better fundamental understanding is needed of the varied ultimate functions and proximate mechanisms of play, and the species-specific play patterns of captive animals, in order to be able to explain exactly what an animal’s play behaviour tells us about its welfare state, and whether and how play might be applied as a tool to improve welfare

The practicality of practice: A model of the function of play behaviour

Abstract The function of play has been a long‐debated topic in animal behaviour. One popular class of accounts is that play offers practice for serious adult behaviour, but little has been done to model the circumstances where this could be true. In this paper, we model an individual who, over the juvenile and subadult ontogenetic periods, has a choice between three behaviours: foraging, playing and rest, where playing improves an individual's ability in some component of a serious adult behaviour. Using stochastic dynamic programming, we show that even when play is more energetically costly and an inferior form of practice than foraging itself, it still may be optimal to play under a variety of circumstances. We offer several instantiations of the play as practice concept to show the possibility of play improving a variety of different adult abilities: antipredatory, foraging and reproductive behaviour. These models show the environmental conditions where play might be expected, as well as the predicted occurrences of play throughout ontogeny. This is a first step in showing the ecological feasibility of the practice hypothesis of play and raises further questions about why playful activity is more beneficial than more deliberate directed practice

Apprivoiser les porcelets pour compenser les effets négatifs d'une mauvaise relation humain‐animal (RHA) des truies

National audienceUne bonne relation humain-animal est importante pour le bien-être animal. Pour évaluer l’impact de la réaction à l’humain des truies sur celles de leurs porcelets, nous avons mesuré le lien entre la réaction de truies à l’approche d’un humain inconnu et la réaction de leurs porcelets au même humain dans un test standard après le sevrage. Nous avons étudié 24 truies et 96 de leurs porcelets de même type génétique. Les truies étaient logées en trois groupesde 18 (±1) individus chacun. Leur réaction à l’approche d’un humain inconnu dans leur enclos a été mesurée à 70 jours de gestation. Suite à ce test, elles ont pu être classées en deux catégories : docile (n=13) ou farouche (n=11). Une semaine avant parturition, elles ont été transférées dans des cases de mise-bas individuelles. Les porcelets issus de ces truies ont été sevrés à 28 jours et élevés par groupes de trois d’une même portée. Deux mâles et deux femelles de chaque portée ont été choisis pour participer à des tests comportementaux. A 32 et 33 jours, soit 4 jours après le sevrage, chaque porcelet a été soumis à un test d’approche volontaire de l’humain dans une salle mesurant 2.7 x 2.7 m. Dans ce test, après 5 minutes d’isolement dans cette salle inconnue, l’humain ayant effectué le test d’approche sur les truies entrait dans la salle pour aller s’asseoir contre un des murs sur un tabouret à hauteur de porcelet. Les comportements du porcelet étaient alors relevés grâce à des analyses vidéos. Une analyse en composante principale ainsi qu’une classification hiérarchique sur composantes principales (HCPC) ont été appliquées afin de classifier les porcelets en fonction de leur réaction à l’humain durant le test. L’HCPC a décrit trois catégories de porcelets : la catégorie dite ‘farouche’ (n=44), constituée de porcelets restant loin de l’humain et plutôt immobiles, la catégorie dite “sociable” (n=20), constituée de porcelets qui s’approchent de l’humain rapidement et restent proches durant le test, et la catégorie dite ‘explorateur’ (n=32), constituée de porcelets qui ne semblent pas affectés par la présence de l’humain et qui explorent la salle. Un test du khi² a montré un effet significatif de la catégorie de la truie sur celle de ses porcelets (X = 8.55, p = 0.013). Les truies farouches donnent naissance en majorité à des porcelets farouches, alors que les truies dociles donnent naissance indifféremment aux trois catégories de porcelets. Une truie farouche a 59% de chances de donner naissance à un porcelet lui aussi farouche, et seulement 9% de chance de donner naissance à un porcelet sociable. Ces premiers résultats semblent montrer que la truie est susceptible de transmettre sa peur de l’humain à ses porcelets et ce après le sevrage. Si cette transmission se fait en dehors de toute implication génétique, apprivoiser les truies pourraient être favorable à la fois au bien-être de ces dernières et à celui de leur porcelet