![]() ![]() the ingestion of saliva or other items), or even compromise gastrointestinal health. If such proxies are inadequate, this could trigger deficit-led oral searching behaviours, induce coping responses (e.g. ![]() captive browsers are often fed grass or lucerne hay, not a natural diet ). Third, nutritional and/or physical differences between wild and captive diets could instead be the key (e.g. Furthermore, these animals' wild food items are naturally patchy, potentially driving the evolution of motivational systems wherein ingestion triggers intense local search: a functionless response if food is provided in feeders. This could lead to foraging behaviours evolving into intrinsically rewarding ‘behavioural needs’. navigating thorns and branches with lips tearing and crushing with bills). First, foraging is naturally time-consuming for both, and accessing food requires extensive oral manipulation (e.g. This suggests three potential similarities between these otherwise divergent groups. By contrast, ungulates resemble parrots, whose self-directed feather-chewing and -plucking is similarly predicted by foraging niche. pacing), and suggests underlying differences in ranging behaviour's plasticity and/or reward value. This could explain why ungulates seldom perform route-tracing SBs (e.g. For example, that natural ranging behaviour seems to have no welfare significance for Ungulata contrasts with Carnivora and Primates. These findings reveal similarities and differences compared to other groups ( Table 1 reviewed by ). Social housing regimes had no effects but naturally promiscuous species had more prevalent SB: an intriguing yet puzzling pattern discussed below. Two other potential risk factors were also explored: species-typical ranging behaviour or activity levels (with no discernible effects), plus social organization. processed pellets), or discrete meals rather than ad libitum. SB was more prevalent in naturally browsing species (those primarily eating non-grass plants like tree leaves) than species naturally reliant on grazing and in individuals fed ‘concentrates’ (e.g. Both species and husbandry effects supported the foraging hypothesis. ![]() created an impressive literature-derived database for 38 ungulate species and ran ground-breaking phylogenetically informed multi-level Bayesian regression models: instead of only using species summary statistics as datapoints (the norm), they also incorporated data on individuals' husbandry (e.g. zoo-housed giraffes, stabled horses and farmed pigs ) are prone to oral SBs, like bar-chewing and tongue-rolling, suggested to derive from vacuum or redirected foraging triggered by artificial diets. conducted a meta-analysis of the prevalence of ‘stereotypic behaviour’ (SB), an ethological welfare indicator in which sub-optimally kept animals perform repetitive actions reflecting frustration, repeated attempts to cope, or neurological impairment (cf. Here we contextualize this new work, and suggest further research it might inspire. ![]() A steady trickle of studies has applied PCMs to animal welfare over the last two decades, Lewis et al. Risk factors can then suggest new ways to improve animal care. This enables the use of phylogenetic comparative methods (PCMs) to identify aspects of natural biology that predispose species to faring poorly or well. Some species tend to thrive in captivity, while others risk health and reproductive problems. ![]()
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