Species-Level Determinants of Stereotypic Behaviour, Reproductive Success, and Lifespan in Captive Parrots (Psittaciformes)
Establishing why related species differ in their typical responses to captivity can reveal fundamental information about the biological, or intrinsic, determinants of welfare for a given taxon. This thesis describes a comparative study conducted to identify intrinsic risk or protective factors for several welfare-sensitive outcomes in captive parrots (Psittaciformes). Welfare measures were: species-typical prevalences of stereotypic feather-damaging behaviour (FDB), other stereotypic behaviours (SB), and diagnosed medical problems in pet parrots; captive reproductive rates and subjective captive breeding “difficulty” in aviculture parrots; and captive lifespan (average relative to maximum) in zoo parrots. I investigated four characteristics suggested to predict poor welfare: large natural group size, high natural foraging effort, ecological specialism, endangeredness; and one, intelligence, suggested as either a risk or protective factor for poor welfare. Species-level data on SB and medical health were generated from responses to a research survey, and data on all other variables were collected from the literature. I tested for predictive relationships between natural traits and welfare outcomes, controlling for phylogenetic non-independence and other confounders. Results were broadly similar for parrots kept as pets (SB data) or for breeding by aviculturists (captive breeding data): Relatively long food search times predicted increased FDB prevalences and greater breeding difficulty. Larger relative brain volumes predicted increased SB prevalences (oral-focused or involving the whole-body) and, along with higher frequencies of reported innovative foraging behaviour, tended to predict decreased reproductive rates. Decreased reproductive rates and greater breeding difficulty were also predicted by increased endangeredness (IUCN) and narrower habitat breadths, respectively. Natural group size was not a predictor. None of the natural biology variables predicted susceptibility to medical problems; and analyses with captive lifespan were inconclusive and will need to be repeated with validated species estimates for average captive lifespan. In conclusion, intelligent parrot species and those with naturally high foraging effort were at increased risk for behavioural and reproductive problems (and potentially, poor welfare) in captivity; and captive breeding was additionally compromised in endangered species and ecological specialists. These findings could inform recommendations about which species may be predisposed to success or difficulty as pets or in breeding programs.