Shigeki Asai

Genetic diversity and extent of gene flow in the endangered Japanese population of Hodgson's hawk-eagle, Spizaetus nipalensis

The Japanese subspecies of Hodgsons Hawk-eagle, Spizaetus nipalensis orientalis , is considered threatened and has been designated as Endangered by the Japanese government. We determined the complete mitochondrial DNA (mtDNA) sequence of this species and designed a primer set to amplify a highly variable region of mtDNA, part of the control region (CR), based on this complete sequence. Using the primers, we amplified the CR and then determined the haplotypes of 178 samples collected at different sites in Japan. A nested cladistic analysis indicated that gene flow within some clades was restricted. The inference key implied that isolation by distance had caused the restriction of gene flow. Moreover, the ranges of the clades in which restricted gene flow was detected overlapped with the ranges of other clades. These results suggest that there is no fragmental population of Hodgsons Hawk-eagle in Japan and that this species has dispersed within short distances, at least in some lineages. Genetic diversity was high in comparison with other species. Therefore, at least in terms of genetic diversity, the Japanese population of Hodgsons Hawk-eagle is probably not in a critical situation.

Nesting habits of the Rufous Vanga in Madagascar

3Laboratory of Animal Sociology, Faculty of Science, Osaka City University, Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan 32.7% for the Cape Sugarbird, lower than the 46.1% obtained for Gurneys Sugarbird during this study. Although fewer nests were located in the Lydenburg stud y area, unsuccessful nesting attempts did not always result from weather conditions, but rather from disturbances at the nest site during the incubation phase. In both species, adverse environmental conditions such as strong winds and heavy rainstorms during the breeding season are a common feature (Winterbottom 1962; Burger et al. 1976). Orange-breasted Sunbirds, N. voilacea, have a higher breeding success rate than Cape Sugarbirds, which occur in the same area, probably due to the protection provided by the closed nests (Broekhuysen 1963). The same was observed for the Malachite Sunbird, N. famosa, and Greater Doublecollared Sunbird, N. afm, which co-occur in the same Pro tea habitat as Gurneys Sugarbird, although nests of the former two species are not as exposed to strong winds and rain. Malachite Sunbird nests in the Lydenburg area are found mostly in shrubs growing in gullies or under rocks in mountainous areas and are well concealed from rain and strong winds (Maclean 1993).

Consequence of Inter Class Competition and Predation on the Adaptive Radiation of Lizards and Birds in the Dry Forest of Western Madagascar

Abstract Species interactions among phylogenetically distant but ecologically related vertebrates were studied in a dry forest of western Madagascar to evaluate whether competition and predation between lizards and birds have reciprocally affected adaptive radiation in Madagascar. Of 49 terrestrial and diurnal birds regularly seen in the study forest, we identified six guilds as carnivore (5 spp.), omnivore (2 spp.), carnivore/insectivore (7 spp.), strict insectivore (15 spp.), insectivore/nectarivore (6 spp.), and frugivore (5 spp.). Twelve lizards species were classified as omnivore (1 sp.), strict insectivore (9 spp.), and insectivore with occasional frugivory and nectarivory (2 spp.). The most dominant guilds of the vertebrates in terms of biomass were folivorous/frugivorous parrots, doves, and lemurs (6.7 kg/ha), followed by insectivorous lizards (1.7 kg/ha) and insectivorous birds (0.8 kg/ha) in the Ampijoroa dry forest. Despite their lower biomass, insectivorous birds appeared to be competitively more advantageous than the lizards in terms of prey consumption speed (230 prey/ha/hr by birds vs. 35 prey/ha/hr by lizards). Insectivorous and carnivorous birds may have kept insectivorous lizards from radiating in various niches in Madagascar, and may have promoted a reclusive lifestyle in lizards.

MORTALITY OF FLEDGLING FEMALES CAUSES MALE BIAS IN THE SEX RATIO OF RUFOUS VANGAS (SCHETBA RUFA) IN MADAGASCAR

Abstract The Rufous Vanga (Schetba rufa) is a cooperative breeder. Although young males typically remain in natal territories, yearling females do not remain, but disperse to breed for themselves. The male-biased sex ratio likely restricts independent reproduction by young males. We analyzed demographic data from a seven-year study of the Rufous Vanga in Madagascar to estimate the mortality for each sex. We also examined the sex ratio at fledging and at hatching, sexing nestlings with DNA analysis on sex chromosomes. Analyses indicated that the biased sex ratio was due to differential mortality of fledglings rather than the bias at birth. We suggest that the delayed dispersal improved survival of auxiliary males.

Individual Differences in the Helping Behaviors of Cooperatively Breeding Rufous Vangas

Abstract The Rufous Vanga breeds cooperatively, with pairs accompanied by one or more helper males. Although the contribution of helpers may be considerable, helping does not enhance reproductive success. In this study, we investigated individual differences in helping behavior and discuss the adaptive significance of helping. Contributions by helpers were very low during the nest building and incubation stages, but were greater during the nestling stage. In the first half of the nestling stage, both one-year-old and older helpers contributed less than breeders, with one-year-old helpers feeding nestlings less frequently than older helpers. However, the contribution of helpers increased during the second half of the nestling stage, while that of breeding females decreased. Both provisioning frequency and the size of food items carried by one-year-old helpers reached the same level of older helpers during the second half of the nestling stage. One-year-old sons of breeding females contributed more than unrelated helpers, however relatedness did not influence significantly the contribution of older helpers. Contribution to provisioning by one-year-old helpers did not influence their fate in subsequent years. Our data did not reveal any direct fitness benefits gained by helping at the nest for one-year-old helpers, but suggested that they helped their mothers in order to gain indirect fitness benefits through lightening their mothers labor. Older helpers may have gained direct fitness benefits through advertising to an unrelated breeding female or by feeding their extra-pair fertilized off-spring.