Abstract: We describe and illustrate methodology for comparing networks from diverse settings. Our empirical base consists of 42 networks from four kinds of species (humans, nonhuman primates, nonprimate mammals, and birds) and covering distinct types of relations such as influence, grooming, and agonistic encounters. The general problem is to determine whether networks are similarly structured despite their surface differences. The methodology we propose is generally applicable to the characterization and comparison of network2013level social structures across multiple settings, such as different organizations, communities, or social groups, and to the examination of sources of variability in network structure. We first fit a p* model (Wasserman and Pattison 1996) to each network to obtain estimates for effects of six structural properties on the probability of the graph. We then calculate predicted tie probabilities for each network, using both its own parameter estimates and the estimates from every other network in the collection. Comparison is based on the similarity between sets of predicted tie probabilities. We then use correspondence analysis to represent the similarities among all 42 networks and interpret the resulting configuration using information about the species and relations involved. Results show that similarities among the networks are due more to the kind of relation than to the kind of animal.

Abstract: Stereotypies are invariant and repetitive behaviour patterns that seemingly have no function, which tend to develop in captive animals faced with insoluble problems and may be indicative of reduced welfare. A 4 year prospective study of the factors influencing the development of stereotypic and redirected behaviours (abnormal behaviour) in a population of 225 young Thoroughbred and part-Thoroughbred horses was conducted between 1995 and 1999. Abnormal behaviour affected 34.7% of the population. Multivariable analysis showed that foals of low- or middle-ranking mares were less likely to develop abnormal behaviour than foals of dominant mares (rate ratio (RR) 0.23, P<0.01; RR 0.48, P<0.01, respectively). Weaning by confinement in a stable or barn was associated with an increased rate of development of abnormal behaviour, compared with paddock-weaning (RR 2.19, P<0.05), and housing in barns, rather than at grass after weaning, was associated with a further increase (RR 2.54, P<0.01). Specific stereotypic and redirected behaviours were then considered as separate outcomes. Crib-biting was initiated by 10.5% of horses at median age 20 weeks, weaving by 4.6% of horses at median age 60 weeks, box-walking by 2.3% of horses at median age 64 weeks and wood-chewing by 30.3% of horses at median age 30 weeks. Wood-chewing developed at a lower rate in horses born to subordinate or mid-ranking mares than in horses born to dominant mares (RR 0.29, P<0.01; RR 0.41, P<0.01, respectively), and at a higher rate in horses kept in barns or stables rather than at grass after weaning (RR 4.49, P<0.001; RR 1A6, P<0.001, respectively). Feeding concentrates after weaning was associated with a 4-fold increase in the rate of development of crib-biting (RR 4.12, P = 0.02). The results of this study support the idea that simple changes in feeding, housing and weaning practices could substantially lower the incidence of abnormal behaviour in young horses.

Abstract: A number of discrimination learning studies suggest that horses attend to spatial cues in preference to visual ones. However, global and relative spatial cues have generally been confounded so it is not clear what information horses actually used. There has also been no study of whether one cue is learnt at the expense of another, or whether multiple cues are encoded but prioritised differently. We therefore carried out a series of studies examining how horses use different cues in learning a food-finding discrimination task. All studies used a criterion for success of 7/10 on two consecutive days (binomial test, p=0.0004).
A pilot study showed that horses could discriminate between three buckets using visual cues (striped, chequered or plain patterns). All four subjects performed significantly above chance levels, although one horse’s performance did not meet the criterion. Three others completed the task in between two and 12 sessions. There were some indications that horses tried to solve the task using irrelevant spatial information.
Nine foals were then taught to find a food reward using the same three patterned buckets placed in a row in any corner of a test arena. In Stage 1 the rewarded bucket was signified both by visual cues (pattern) and by relative spatial cues (left, middle or right position). Foals took between 2 and 10 days to complete the task , whereupon the cues were separated. Foals then had to ignore the inappropriate cue in Stage 2. For the Spatial group (n=5), only relative position remained relevant; for the Visual Group (n=4) bucket pattern indicated the rewarded bucket. Spatial group foals completed Stage 2 faster than Visual group foals (Mann Whitney U, z=-2.71, p=0.008). Position cues seemed to overshadow learning about visual cues: Visual group foals persisted in responding to the previously correct position and none reached criterion within the maximum available time (15 days to complete both stages).
Finally, five adult horses and one 10 month old filly learnt to find a reward in one of three identical yellow buckets whose position in an array (left, middle or right) and location within the test arena were consistent. On reaching criterion, responses were recorded in two unrewarded probe trials where the buckets were either shifted along the same axis or rotated by 90º. When the array was shifted, five out of six horses chose the previously correct position (binomial test, p=0.018) that was now in a new location within the school. Choices were not significantly different from random when the array was rotated, suggesting that the horses had learnt something about global cues even if they did not use them in selecting a bucket.
At the small scale tested, relative spatial cues (position with regard to other goals) seemed to be more important to horses than either visual cues or global spatial cues, though the latter appeared to be encoded to some extent. Reliance on spatial cues may reflect their usefulness in the horse’s natural lifestyle in navigating over long distances and feeding on visually similar plants.

Abstract: High-latitude environments show extreme seasonal variation in physical and biological variables. The classic paradigm of Arctic marine ecosystems holds that most biological processes slow down or cease during the polar night. One key process that is generally assumed to cease during winter is diel vertical migration (DVM) of zooplankton. DVM constitutes the largest synchronized movement of biomass on the planet, and is of paramount importance for marine ecosystem function and carbon cycling. Here we present acoustic data that demonstrate a synchronized DVM behaviour of zooplankton that continues throughout the Arctic winter, in both open and ice-covered waters. We argue that even during the polar night, DVM is regulated by diel variations in solar and lunar illumination, which are at intensities far below the threshold of human perception. We also demonstrate that winter DVM is stronger in open waters compared with ice-covered waters. This suggests that the biologically mediated vertical flux of carbon will increase if there is a continued retreat of the Arctic winter sea ice cover.

Abstract: Laterality is now known to be an ubiquitous phenomenon among the vertebrates. Particularly, laterality of auditory processing has been demonstrated in a variety of species, especially songbirds and primates. Such a hemispheric specialization has been shown to depend on factors such as sound structure, species specificity and types of stimuli. Much less is known on the possible influence of social familiarity although a few studies suggest such an influence. Here we tested the influence of the degree of familiarity on the laterality of the auditory response in the domestic horse. This species is known for its social system and shows visible reactions to sounds, with one or two ears moving towards a sound source. By comparing such responses to the playback of different conspecific whinnies (group member, neighbor and stranger), we could demonstrate a clear left hemisphere (LH) preference for familiar neighbor calls while no preference was found for group member and stranger calls. Yet, we found an opposite pattern of ear side preference for neighbor versus stranger calls. These results are, to our knowledge, the first to demonstrate auditory laterality in an ungulate species. They open further lines of thought on the influence of the social “value” of calls and the listener's arousal on auditory processing and laterality.