Breeding Biology and Nesting Success of Palila

We studied the breeding biology of Palila (Loxioides bailleui) at 85 nests from 20 April to 14 September 1988. Eggs were laid over a 139-day period and incubation averaged 16.6 days. The female incubated 85.2% of daylight hours and males fed incubating females. Modal clutch size was 2 (x̄ = 2.0) and...

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Bibliographic Details
Published in:The Condor (Los Angeles, Calif.) Calif.), 1990-11, Vol.92 (4), p.1012-1021
Main Authors: Pletschet, Sandra M., Kelly, Jeffrey F.
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal nesting
Animal, plant and microbial ecology
Animals
Autoecology
Aves
Aviculture
Biological and medical sciences
Bird nesting
Breeding
Breeding seasons
Eggs
Food availability
Fundamental and applied biological sciences. Psychology
Hatching
Incubation
Loxioides bailleui
Reproductive success
Vertebrata
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Summary:We studied the breeding biology of Palila (Loxioides bailleui) at 85 nests from 20 April to 14 September 1988. Eggs were laid over a 139-day period and incubation averaged 16.6 days. The female incubated 85.2% of daylight hours and males fed incubating females. Modal clutch size was 2 (x̄ = 2.0) and an average of 1.4 nestlings fledged per successful nest. Nestlings were in the nest an average of 25.3 days. Both females and males fed nestlings with the rate of feeding decreasing as the nestlings grew older. Palila nesting success was 25%, reduced primarily by hatching failure and depredation of nestlings. Hatching failure, due to inviable eggs or desertion, occurred in 41% of nests with eggs (55% of nest mortality). Egg depredation was rare (5% of nest mortality). Inbreeding and low food availability are postulated as the major causes for poor hatching success. Twenty-one percent of nests with nestlings were depredated (35% of nest mortality). Brood reduction was observed in 47% of nests with two nestlings. Nest success decreased significantly late in the breeding season, from 46.4% to 12.8%. During this same period, the abundance of mamane (Sophora chrysophylla) pods, the Palila's primary food, also decreased significantly. Stepwise discriminant analysis correctly classified the fate of 79% of nests using egg-laying date, nest-tree area, and distance between the nest tree and adjacent trees as variables.
ISSN:0010-5422
1938-5129
DOI:10.2307/1368737