New Zealand Journal of Ecology (1996) 20(2): 277- 284

Sign left by brushtail possums after feeding on bird eggs and chicks

Research Article
K. P. Brown 1
H. Moller 2
J. Innes 3
  1. Ecosystem Consultants, P.O. Box 6161, Dunedin, New Zealand
  2. Department of Zoology, University of Otago, P.O. Box 56, Dunedin, New Zealand
  3. Manaaki Whenua - Landcare Research, Private Bag 3127, Hamilton, New Zealand

Brushtail possums (Trichosurus vulpecula) were offered Japanese quail (Coturnix japonica) eggs and day-old domestic chickens (Gallus gallus) during a captive feeding trial. Differences in feeding sign left by possums of differing sex, age class, and hunger were slight or absent. Possum feeding trial remains were also compared with remains of North Island robin (Petroica australis longipes) and North Island tomtit (Petroica macrocephala toitoi) eggs and chicks preyed on by ship rats (Rattus rattus) at videoed nests. Eggs fed on by possums were frequently crushed or had crushed shell margins whereas eggs preyed on by ship rats often had jagged shell margins and separate small shell fragments. Possums that ate chickens mostly left partially eaten carcasses with torn flesh, of which 50% were at least partially skinned. Ship rats left partially eaten birds with chewed flesh and bones but did not skin carcases. Possums rarely spat out shell pellets but produced feather pellets on eight of 13 occasions. Egg shell remains left by possums were indistinguishable from those left by ship rats for 11% of 72 shell remains examined from the feeding trial. Characteristic sign should enable possums and ship rats to be differentiated as predators after most but not all predations.