Morphology and migration of Chrysococcyx lucidus, an Australasian cuckoo

Abstract

The bill widths and dates of collection of up to 427 museum skins (depending on the analysis) of the cuckoo Chrysococcyx lucidus are considered. The species occurs, and breeds, at temperate latitudes of Australasia only during the southern summer, and it occurs, apparently without breeding, in the far north of its range only during the southern winter. Between 10° and 35°S (New Caledonia etc and parts of Australia) the cuckoo seems to occur all year and may breed over wide areas. The average bill width was significantly greater for New Zealand specimens than for those collected in Tasmania, which in turn tended to be wider-billed than those from Western Australia. However, separating these populations subspecifically does not seem warranted, and Ch. lucidus plagosus (Latham, 1801) should be synonymised with the nominate race. Birds from the Lesser Sunda Islands and New Guinea had, on average, narrower bills than those from New Britain, New Ireland, and the Solomon Islands. This is consistent with the hypothesis that the cuckoos breeding in New Zealand migrate to the New Britain-Solomons archipelago, and that Western Australian birds migrate to New Guinea and the Lesser Sundas, On the evidence of bill width, Tasmanian birds could migrate to any of these wintering grounds. The series from New South Wales and Queensland were multi-modal for bill width, with narrow-billed birds occurring all year, and wider-billed individuals during the months of migration. This suggests that New Zealand cuckoos migrate via eastern Australia rather than by a direct transoceanic route as is currently supposed.

Keywords:

• Chrysococcyx lucidus
• Cuculinae
• cuckoo
• Australasia
• morphology
• migration
• wintering grounds
• migration routes