A CROSS-FOSTERING EXPERIMENT BETWEEN THE ENDANGERED TAKAHE (PORPHYRIO-MANTELLI) AND ITS CLOSEST RELATIVE, THE PUKEKO (P-PORPHYRIO)

New Zealand's avifauna is characterised by a variety of endemic, often flightless, birds most of which are critically endangered. One of the se, the takahe, is a large flightless rail which has been reduced to o ne population of 115 birds in its natural alpine habitat plus 52 other s introduced on four small offshore islands. By contrast the takahe's closest extant relative, the pukeko, has been highly successful since its invasion of New Zealand within the past 800 years. This paper summ arises results of a pilot study in which takahe eggs were cross-foster ed to pukeko nests on Mana Island in order to increase the number of j uveniles produced by each pair of takahe. Over two seasons, 67% (8/12) of the cross-fostered eggs hatched successfully with 25% (2/8) of the resulting young surviving to one year of age. These results were not significantly different from 42% (5/12) and 40% (2/5) hatching and fle dging success of takahe-reared eggs from the same clutches. Low fledgi ng success of cross-fostered chicks may reflect poor quality of takahe eggs per chicks rather than poor parental care by the pukeko foster p arents, as hatching success of all parent-reared takahe eggs on Mana I sland was only 22% (5/23) over the course of this research.