Thermal characteristics of wild and captive Micronesian kingfisher nesting habitats

Published source details Kesler D.C. & Haig S.M. (2004) Thermal characteristics of wild and captive Micronesian kingfisher nesting habitats. Zoo Biology, 23, 301-308.
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Summary

The Guam kingfisher Halcyon cinnamomina cinnamomina is restricted to captive breeding facilities (on Guam and mainland USA) following extinction in the wild due to predation by the introduction brown tree snake Boiga irregularis. A study was undertaken at facilities in USA and in habitats used by wild Pohnpei kingfishers H. c. reichenbachii on Pohnpei (Federated States of Micronesia) to determine if thermal characteristics of captive breeding aviaries are likely to influence reproductive success of Guam kingfishers.

Transmitters were fitted to 26 wild Pohnpei kingfishers. These were tracked to locate nests, and temperature loggers were placed 30 cm below nest cavity entrances in 18 nest holes, to record ambient temperatures during three, 3-day periods in September 2001.

Study aviaries (15 in total) were located in nine of 11 institutions in the USA attempting to captive-breed Guam kingfishers. Temperatures were recorded (as wild nests) in aviaries from 6 February to 26 October 2002 (approximate breeding season).

Environmental temperatures were compared to the thermoneutral zone (TNZ; i.e. temperature range not requiring metabolic energy for thermoregulation) of adult kingfishers.

Compared to aviaries, habitat used by Pohnpei kingfishers had 3.2ºC higher daily maximum and minimum temperatures, and the proportion of time when temperatures were in their TNZ (23.8ºC to c.38ºC) was 45% greater. Magnitudes of temperature fluctuation in captive and wild environments were similar. In aviaries in which kingfishers bred, daily maximum temperatures were 2.1ºC higher and temperatures within the TNZ 25% more than in aviaries in which they did not breed. Results suggest that consideration should be given to increasing temperatures in captive breeding facilities to potentially improve reproductive success.

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