The evolution of social play in songbirds, parrots and cockatoos - emotional or highly complex cognitive behaviour or both?

Social play has been described in many animals. However, much of this social behaviour among birds, particularly in adults, is still relatively unexplored in terms of the environmental, psychological, and social dynamics of play. This paper provides an overview of what we know about adult social play in birds and addresses areas in which subtleties and distinctions, such as in play initiation and social organisation and its relationship to expressions of play, are considered in detail. The paper considers emotional, social, innovative, and cognitive aspects of play, then the environmental conditions and affiliative bonds, suggesting a surprisingly complex framework of criteria awaiting further research. Adult social play has so far been studied in only a small number of avian species, exclusively in those with a particularly large brain relative to body size without necessarily addressing brain functions and lateralization. When lateralization of brain function is considered, it can further illuminate a possibly significant relevance of play behaviour to the evolution of cognition, to management of emotions, and the development of sociality.

The conservation status of Tanimbar corella and blue-streaked lory on the Tanimbar Islands, Indonesia: results of a rapid contextual survey

Two parrot species, Tanimbar corella Cacatua goffini and blue-streaked lory Eos reticulata, endemic to the Tanimbar Islands, Indonesia, were regularly trapped and sold into the international wild bird trade prior to 1992. Following concerns about numbers entering the trade, but with little knowledge of the remaining wild population or socio-economic role of bird trapping on the islands, international trade in both species was suspended at the 1992 CITES meeting. This paper reports on a rapid survey conducted on the islands in 1993 as a follow-up to the decision on trade. The survey attempted to determine the status of the wild populations, the distribution and activity of the human population, the interaction between Tanimbar corella and agriculture, and the structure of the local commodity-chain for wild-caught parrots. We found that: (a) both parrot species were widely distributed and present at relatively high densities across the largest island in the group, Yamdena; (b) catching of parrots is geographically limited; (c) in the case of Tanimbar corella, at least, the catching is of birds raiding crops and probably involves mainly immature and non-reproductive birds; (d) the international and domestic ban on catching was generally adhered to locally but the reasons for the ban were not widely understood, contributing to a general mistrust of conservationists that still remains. Although not advocating a lifting of the ban on trapping, we do conclude that in this case invoking the precautionary principle without proper consideration of local context may have been counterproductive to conservation goals.

Characteristics of tree hollows used by Australian birds and bats

Many hundreds of species of wildlife worldwide are dependent on tree hollows (cavities) for their survival. I reviewed the published literature for hollow-using Australian birds and microbats to document their tree-hollow requirements and to guide future research and management. Such information is vital to the conservation of these species. The hollow requirements of only 35 of 114 hollow-using bird species and 15 of 42 hollow-using microbat species were documented in some detail. This overall paucity of information limits the ability to manage for the future requirements of species. However, some generalisations can guide management until further studies are conducted. Most species used a variety of available tree species, and the extensive use of dead trees probably reflects the high likelihood of these trees containing hollows. Birds (other than large parrots) and bats chose hollow entrances of a size close to body width. Large parrots require large hollows, with a preference for large vertical spouts and trunk hollows. Few birds or bats demonstrated an absolute requirement for high (>10 m) tree hollows, with most (70%) using some hollows with entrances ≤5 m above ground. Temperature has been postulated to influence roost selection among microbats because it enables passive rewarming from torpor and there is some evidence from Australian bats to support this. Many studies suggest a future shortage of hollow-bearing trees. Currently, artificial hollows appear to be the most likely interim solution to address this. Knowledge of the natural hollow requirements of species can be used to refine artificial-hollow designs. An increase in research effort is needed to address the many gaps in knowledge that currently exist. Priorities for research include (1) many additional studies to document the characteristics of the hollow-bearing trees used by species of microbat, (2) the need to conduct long-term bioregional studies of hollow-bearing tree attrition to help identify where management responses are most needed and (3) investigating whether fire plays a significant role in the creation of tree hollows of a range of size classes and therefore may have a management use. Such information has broad relevance because it will provide ecological insight that can be applied to the management of hollow-using birds and bats elsewhere in the world.