The New Zealand falcon, or kārearea, population is actually made up of two different subspecies, scientists have decided.
Researchers from Massey University declare the subspecies split in a new study analysing the physical and genetic differences between kārearea from different parts of the New Zealand. The research is published in IBIS, International Journal of Avian Science.
In collecting data on bird sizes, the researchers left no stone unturned. They dug up kārearea weights and measurements from studies dating back to the 1970’s as well data from frozen specimens of kārearea killed by accidental vehicle collisions, electrocution or poisoning and submitted to Department of Conservation offices. Preserved skins in the collections of Te Papa Museum of New Zealand, Canterbury Museum and Auckland War Memorial Museum were also examined.
Carefully analysing the size, weight and genetic differences of a total of 245 birds, the researchers found that kārearea fell into two distinct clusters – predominantly separating North Island and South Island individuals.
Study author, Professor Trewick of the Institute of Agriculture and Environment says, “kārearea vary considerably in size and colouration, over and above the differences between the males and females that are typical of raptors, and this variability has caused confusion since its earliest observation in the 1870s.
“Differences in size and other attributes among spatially separated populations could represent adaptation to local conditions and by recognising two distinct subspecies in kārearea, we will be able to identify the patterns of diversity within the species and understand the distinct evolutionary ecology of each.”
The supspecies have been named Falco novaeseelandiae novaeseelandiae from the South Island and Falco novaeseelandiae ferox for the smaller North Island form.
The research was more than just an exercise in naming; identifying of subspecies allows conservationists to ensure that the distinct lineages preserved.
“This finding supports an informal conservation management strategy to avoid translocation and crossbreeding in captivity of falcons from the two islands,” says Professor Trewick.
The Department of Conservation estimates there are between 5,000 and 8,000 kārearea left, but this number is uncertain.
Read more about the research on Scimex.org
Featured image: Adapted from Wikimedia / Tony Mills.