To mix or not to mix? Evaluating breeding productivity in mixed species bird enclosures within European zoos.
Housing animals within mixed species aggregations is often believed to offer a more naturalistic captive environment by providing behavioural and social enrichment, and has become an integral design feature for many zoos across the world. There is however, a common perception among zoo professionals that for birds in particular, breeding performance may be reduced when housing them within mixed species environments. In order to investigate this perception, three objectives were outlined, which aimed to evaluate the impact that mixed species housing has on bird breeding performance within European zoo collections. Objective one compared the breeding performance of bird species housed within mixed species enclosures versus when those species were housed in single species enclosures. This was followed by objective two which identified the factors that may be influencing bird breeding performance when housed within mixed species enclosures only. Finally objective three discussed the use of historical zoo records for evaluating breeding performance within mixed species enclosures. To test these objectives the breeding performance of birds housed in mixed (and where applicable single species) enclosures were collected via questionnaire (n=88 zoos) and via historical records (n=2 zoos). Analysis revealed that 55% of species tested were considered to breed better when housed as a single species. Furthermore a number of factors were found to impact on breeding performance within mixed species enclosures; including breeding sociality, fledge time and the presence of non-bird taxa, however these factors were found to be effected by bird phylogeny. Comparisons with results from historical records suggest that questionnaires were a suitable method for assessing breeding performance. In addition records data highlighted that birds housed in mixed enclosures were subject to many transfers’ between enclosures, which may be impacting on the ability to breed successfully. As the first attempt at quantifying the influence that mixing bird species has on breeding performance, evidence supports the perceptions that for some species breeding may be reduced. This result is not consistent across all species and thus requires further investigation to assess how these breeding issues may be impacting upon future population sustainability of birds housed in European zoos.
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