Impact injuries and probability of survival in a large semiurban endemic pigeon in New Zealand, Hemiphaga novaeseelandiae.

ABSTRACT

The New Zealand Pigeon or kereru (Hemiphaga novaeseelandiae) frequently collides with windows and vehicles. In this study of 146 kereru collected from 1996 to 2009, we used 118 radiographs and 91 necropsies to determine skeletal and soft tissue injuries. Vehicle collisions resulted in more damage to the extremities (wing and femur), whereas collisions with windows resulted in trauma to the head, fractures/dislocations of the coracoids and clavicles, and ruptured internal organs. Soft tissue injuries included damage to the flight muscles and heart ruptures caused by fractured coracoid bones, as well as extensive bruising of pectoral muscles and hemorrhaging of the lungs. Rehabilitation time was not related to number of skeletal injuries sustained, nor was the time until death for those that did not survive. In general, kereru with greater numbers of injuries were less likely to survive rehabilitation. Flight speed and force calculations suggest that a 570-g kereru would collide with 3-70 times the force of smaller birds (5-180 g); this may explain the discrepancies between the injuries characterized here and those reported for North American passerines. The differences in injuries sustained from collisions with windows and cars can be used to inform rehabilitators about the possible nature of injuries if the source of impact is known.