Natal and breeding dispersal of northern New Zealand dotterels

Dispersal patterns of juvenile northern New Zealand dotterels have been analysed, based on sight recoveries of birds colour-banded as chicks between 1986 and 1998. Birds bred 0-196 km from their natal site, with an average distance of 31 km and a median of 22 km. About 18% of birds returned to their natal site to breed and nearly all (93%) bred within 70 km of their natal site. Between fledging and breeding most juveniles moved much further than indicated by their natal dispersal distance. Natal and first breeding sites are known for 120 birds; 77 of these were raised in the Northland-Auckland area and 43 in the Coromandel-Bay of Plenty area. There appears to be very little movement of juveniles between the two areas; over a period of 13 years only nine of 240 banded chicks that fledged were seen outside their natal area and no birds raised in one area were found breeding in the other. Analysis of breeding dispersal by adults shows that they move less than juveniles; none of 25 adults that moved from one breeding site to another crossed between the two areas. There is apparently very little effective dispersal (gene flow) between birds in the two areas and they currently appear to constitute isolated groups. Information from some parts of the species range is sparse but it appears likely that birds in the Far North and the Auckland west coast are part of the Northland-Auckland group, and that birds on Great Barrier Island and in the Gisborne area are part of the Coromandel-Bay of Plenty group. The status of birds on the Waikato west coast is unknown. Managed sites should be maintained in the two areas; the distribution and number of managed sites within each area should take account of natal dispersal distances. Important areas currently without managed sites that may require them to maintain the range of the species include the Far North and northern and southern sections of the west coast.