Geology topics

Dylan C. Kesler

Publications and source records attributed to Dylan C. Kesler.

21 records · Page 2Linked to original sources

USGS2005

Microclimate and nest-site selection in Micronesian Kingfishers

We studied the relationship between microclimate and nest-site selection in the Pohnpei Micronesian Kingfisher (Todiramphus cinnamominus reichenbachii) which excavates nest cavities from the mudlike nest structures of arboreal termites (Nasutitermes sp.) or termitaria. Mean daily high temperatures at termitaria were cooler and daily low temperatures were warmer than at random sites in the forest. Results also indicate that termitaria provided insulation from temperature extremes, and that temperatures inside termitaria were within the thermoneutral zone of Micronesian Kingfishers more often than those outside. No differences were identified in temperatures at sites where nest termitaria and nonnest termitaria occurred or among the insulation properties of used and unused termitaria. These results suggest that although termitaria provide insulation from thermal extremes and a metabolically less stressful microclimate, king-fishers did not select from among available termitaria based on their thermal properties. Our findings are relevant to conservation efforts for the critically endangered Guam Micronesian Kingfisher (T. c. cinnamominus) which is extinct in the wild and exists only as a captive population. Captive breeding facilities should provide aviaries with daily ambient temperatures ranging from 22.06 A?C to 28.05 A?C to reduce microclimate-associated metabolic stress and to replicate microclimates used by wild Micronesian Kingfishers.

Pacific Science↗

USGS2004

Selection of arboreal termitaria for nesting by cooperatively breeding Micronesian Kingfishers Todiramphus cinnamominus reichenbachii

Limited nest-site availability appears to be an important factor in the evolution of delayed dispersal and cooperative breeding in some cavity-nesting species. The cooperatively breeding Pohnpei subspecies of Micronesian Kingfisher Todiramphus cinnamominus reichenbachii excavates nest cavities from the nests of arboreal termites Nasutitermes spp., or termitaria. In this first published description of nest-sites for this subspecies, we used surveys, remote sensing and radiotelemetry to evaluate the relationship between nest-site availability and co-operation. Results illustrate that nest termitaria are higher in the forest canopy, larger in volume and occur in areas with more contiguous canopy cover than unused termitaria. Nest termitaria were selected independently of the proximity to forest edges and territory boundaries, and we found no difference in characteristics of termitaria used by cooperative groups and breeding pairs. Logistic regression modelling indicated that termitaria with nest-like characteristics were not limited in abundance, suggesting that neither the prospects of inheriting nesting resources nor limited nest-site abundance are probable explanations for delayed dispersal in the Pohnpei subspecies of Micronesian Kingfisher.

Pohnpei↗

USGS2004

Thermal characteristics of wild and captive Micronesian Kingfisher nesting habitats

To provide information for managing the captive population of endangered Guam Micronesian kingfishers ( Halcyon cinnamomina cinnamomina ), four biologically relevant thermal metrics were compared among captive facilities on the United States mainland and habitats used by wild Micronesian kingfishers on the island of Pohnpei ( H. c. reichenbachii ), Federated States of Micronesia. Additionally, aviaries where kingfishers laid eggs were compared to those in which birds did not attempt to breed. Compared to aviaries, habitats used by wild Pohnpei kingfishers had 3.2°C higher daily maximum and minimum temperatures and the proportion of time when temperatures were in the birds' thermoneutral zone was 45% greater. No differences were found in the magnitude of temperature fluctuation in captive and wild environments. In captive environments in which birds bred, daily maximum temperatures were 2.1°C higher and temperatures were within the thermoneutral zone 25% more often than in the aviaries where the kingfishers did not breed. No differences were found in the magnitude of temperature fluctuation or the daily minimum temperature. Results suggest that the thermal environment has the potential to influence reproduction, and that consideration should be given to increasing temperatures in captive breeding facilities to improve propagation of the endangered Micronesian kingfisher.

Pohnpei↗