The influence of pre-experimental experience on social discrimination in rats (Rattus norvegicus)

The authors used laboratory rats (Rattus norvegicus) of known relatedness and contrasting familiarity to assess the potential effect of preexperimental social experience on subsequent social recognition. The authors used the habituation-discrimination technique, which assumes that multiple exposures to a social stimulus (e.g., soiled bedding) ensure a subject discriminates between the habituation stimulus and a novel stimulus when both are introduced simultaneously. The authors observed a strong discrimination if the subjects had different amounts of preexperimental experience with the donors of the 2 stimuli but a weak discrimination if the subjects had either equal amounts of preexperimental experience or no experience with the stimuli. Preexperimental social experience does, therefore, appear to influence decision making in subsequent social discriminations. Implications for recognition and memory research are discussed

Unpredictable movement as an anti-predator strategy

Prey animals have evolved a wide variety of behaviours to combat the threat of predation, and these have been generally well studied. However, one of the most common and taxonomically widespread antipredator behaviours of all has, remarkably, received almost no experimental attention: so-called ‘protean’ behaviour. This is behaviour which is sufficiently unpredictable to prevent a predator anticipating in detail the future position or actions of its prey. In this study, we used human ‘predators’ participating in 3D virtual reality simulations to test how protean (i.e. unpredictable) variation in prey movement affects participants’ ability to visually target them as they move (a key determinant of successful predation). We found that targeting accuracy was significantly predicted by prey movement path complexity, although, surprisingly, there was little evidence that high levels of unpredictability in the underlying movement rules equated directly to decreased predator performance. Instead, the specific movement rules differed in how they impacted on targeting accuracy, with the efficacy of protean variation in one element depending on the values of the remaining elements. These findings provide important insights into the understudied phenomenon of protean antipredator behaviour, which are directly applicable to predator-prey dynamics within a broad range of taxa

Response to novelty as an indicator of reptile welfare

Whilst a great deal of research has been focused on identifying ways to assess the welfare of captive mammals and birds, there is comparatively little knowledge on how reptilian species are affected by captivity, and the ways in which their welfare can be accurately assessed. The present study investigated response to novelty - a commonly used approach to assess anxiety-like behaviour and hence welfare in non-human animals – in two species of reptile with the aim of determining whether this approach could be successfully translated from use in mammalian and avian species for use in reptiles, and whether we could also identify reptile-specific and/or species-specific behaviours. Eight red-footed tortoises (Chelonoidis carbonaria) and seventeen bearded dragons (Pogona vitticeps) were observed individually in both familiar and novel environments for 10 minute time periods, and their behaviour recorded. Tortoises were found to begin locomotion sooner when placed in a familiar environment than when placed in a novel environment, they extended their necks further in a familiar environment and their neck length increased over time in both familiar and novel environments, suggesting an overall anxiety-like response to novelty as seen in non-reptilian species. In contrast, whilst bearded dragons exhibited significantly more tongue-touches in a novel, compared to a familiar, environment, they showed no difference between familiar and novel environments in their latency to move. This result suggests that, whilst the dragons appeared to discriminate between the two environments, this discrimination was not necessarily accompanied by an anxiety-like response. This study has confirmed the translatability of response to novelty as an approach to assess anxiety- like behaviour in one species of reptile, as well as identifying species-specific behaviours that have the potential to be used in future studies when assessing the welfare of reptiles in response to captive environments, but our results also highlight the need to be aware of species differences within a class as diverse as reptilia

Humans can identify reward-related call types of chickens

Humans can decode emotional information from vocalizations of animals. However, little is known if these interpretations relate to the ability of humans to identify if calls were made in a rewarded or non-rewarded context. We tested whether humans could identify calls made by chickens (Gallus gallus) in these contexts, and whether demographic factors or experience with chickens affected their correct identification context and the ratings of perceived positive and negative emotions (valence) and excitement (arousal) of chickens. Participants (n = 194) listened to eight calls when chickens were anticipating a reward, and eight calls in non-rewarded contexts, and indicated whether the vocalizing chicken was experiencing pleasure/displeasure, and high/low excitement, using visual analogue scales. Sixty-nine per cent of participants correctly assigned reward and non-reward calls to their respective categories. Participants performed better at categorizing reward-related calls, with 71% of reward calls classified correctly, compared with 67% of non-reward calls. Older people were less accurate in context identification. Older people's ratings of the excitement or arousal levels of reward-related calls were higher than younger people's ratings, while older people rated non-reward calls as representing higher positive emotions or pleasure (higher valence) compared to ratings made by younger people. Our study strengthens evidence that humans perceive emotions across different taxa, and that specific acoustic cues may embody a homologous signalling system among vertebrates. Importantly, humans could identify reward-related calls, and this ability could enhance the management of farmed chickens to improve their welfare

Assessing the external validity of successive negative contrast – implications for animal welfare

When unexpectedly switched from a preferred to a less preferred food reward, non-human animals may decrease consumption below that when only receiving the less preferred reward - a successive negative contrast (SNC) effect. SNC has been proposed as an indicator of animal welfare, however, to be an effective measure it should show external validity; by being demonstrable outside of highly standardised laboratory settings. We therefore investigated whether the SNC effect typically shown in laboratory rats could be observed in owned (pet) rats from heterogeneous non-laboratory environments. Subjects (N=14) were tested in a consummatory SNC paradigm with solid food rewards. Rats in the ‘shifted’ group received a high-value reward for ten days (pre-shift), a low-value reward for six days (post-shift), then one additional day of high-value reward (re-shift). Rats in the ‘unshifted’ group always received the same low-value reward. ‘Shifted’ rats consumed more food during pre-shift and re-shift trials, but ate significantly less of the low-value food than ‘unshifted’ animals in the post-shift trials – a SNC effect. This confirms the external validity of the SNC paradigm, extending reproducibility to outside the laboratory, indicating that it can translate across contexts, thus enhancing its potential use as a welfare indicator

Can sleep and resting behaviours be used as indicators of welfare in shelter dogs (Canis lupusfamiliaris)?

Previous research on humans and animals suggests that the analysis of sleep patterns may reliably inform us about welfare status, but little research of this kind has been carried out for non-human animals in an applied context. This study explored the use of sleep and resting behaviour as indicators of welfare by describing the activity patterns of dogs (Canis lupus familiaris) housed in rescue shelters, and comparing their sleep patterns to other behavioural and cognitive measures of welfare. Sleep and activity patterns were observed over five non-consecutive days in a population of 15 dogs. Subsequently, the characteristics of sleep and resting behaviour were described and the impact of activity on patterns of sleep and resting behaviour analysed. Shelter dogs slept for 2.8% of the day, 14.3% less than previously reported and experienced less sleep fragmentation at night (32 sleep bouts). There were no statistically significant relationships between behaviours exhibited during the day and sleep behaviour. A higher proportion of daytime resting behaviour was significantly associated with a positive judgement bias, less repetitive behaviour and increased time spent coded as ‘relaxed’ across days by shelter staff. These results suggest that, in the context of a busy shelter environment, the ability to rest more during the day could be a sign of improved welfare. Considering the non-linear relationship between sleep and welfare in humans, the relationship between sleep and behavioural indicators of welfare, including judgement bias, in shelter dogs may be more complex than this study could detect

The impact of egg incubation temperature on the personality of oviparous reptiles

Personality traits, defined as differences in the behavior of individual animals of the same species that are consistent over time and context, such as ‘boldness,’ have been shown to be both heritable and be influenced by external factors, such as predation pressure. Currently, we know very little about the role that early environmental factors have upon personality. Thus, we investigated the impact of incubation temperature upon the boldness on an oviparous reptile, the bearded dragon (Pogona vitticeps). Eggs, from one clutch, were incubated at two different average temperatures within the normal range. After hatching the lizards were raised under the same environmental conditions. Novel object and novel environment tests were used to assess personality. Each test was repeated in both the short term and the long term. The results revealed that incubation temperature did impact upon ‘boldness’ but only in the short term and suggests that, rather than influencing personality, incubation temperature may have an effect on the development of behavioral of oviparous reptiles at different stages across ontogeny

Plant ecology meets animal cognition: impacts of animal memory on seed dispersal

We propose that an understanding of animal learning and memory is critical to predicting the impacts of animals on plant populations through processes such as seed dispersal, pollination and herbivory. Focussing on endozoochory, we review the evidence that animal memory plays a role in seed dispersal, and present a model which allows us to explore the fundamental consequences of memory for this process. We demonstrate that decision-making by animals based on their previous experiences has the potential to determine which plants are visited, which fruits are selected to be eaten from the plant and where seeds are subsequently deposited, as well as being an important determinant of animal survival. Collectively, these results suggest that the impact of animal learning and memory on seed dispersal is likely to be extremely important, although to date our understanding of these processes suffers from a conspicuous lack of empirical support. This is partly because of the difficulty of conducting appropriate experiments but is also the result of limited interaction between plant ecologists and those who work on animal cognition

ICAR: endoscopic skull‐base surgery

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