Invasion risks of exotic parrots via the pet trade
Margaret Stanley1, Ellery McNaughton1, Rachel Fewster2 and Josie Galbraith3
1 Te Kura Mātauranga Koiora School of Biological Sciences, Waipapa Taumata Rau University of Auckland, Tāmaki Makaurau Auckland, Aotearoa New Zealand
2 Te Kura Tatauranga Department of Statistics, Waipapa Taumata Rau University of Auckland, Tāmaki Makaurau Auckland, Aotearoa New Zealand
3 Tāmaki Paenga Hira Auckland War Memorial Museum, Tāmaki Makaurau Auckland, Aotearoa New Zealand (JGalbraith@aucklandmuseum.com)
The global trade in companion animals plays a major role in facilitating the spread of invasive species, with this now arguably the most likely pathway for the establishment of exotic birds in Aotearoa New Zealand, either through deliberate release or accidental escape. Although any one incident may only involve a few individuals, the cumulative effect of these escapes over time increases the likelihood of establishment. We analysed online listings of lost birds from two popular websites in New Zealand to evaluate the invasion risk from pet birds. A total of 1205 birds were listed as lost over ~3.5 years, a rate of loss of 331 birds per year. Parrots made up 92% of all lost birds, with human population size and median income influencing rate of loss. While single individuals accounted for 77% (n=931) of lost birds, the remainder were lost as a part of a group (n=96 groups, group size range 2–20). Simulations of propagule pressure show that the proportion of time with at least one male-female pair at large somewhere in Auckland is very high for species such as ring-necked parakeets (Psittacula krameria) and Alexandrine parakeets (Psittacula eupatria). Many of these species have proved highly invasive in other parts of the world, and their establishment here would have serious consequences for native ecosystems. Given the expense and difficulty of eradicating or managing invasive birds, preventing their establishment is the most effective way of protecting native birds from this type of threat.