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 offspring.
Although the family Vangidae provides one of the most striking examples of adaptive radiation in the avifauna of Madagascar, basic information on the breeding biology of each species is lacking. To examine the breeding system of the Tylas Vanga Tylas eduardi, a species endemic to Madagascar, we studied the contributions made by males and females of two pairs (involving four nests) to nest building, incubating, brooding, and feeding the young. The study was conducted from October 2007 to January 2008 at Ranomafana National Park, situated in southeastern Madagascar. Males had dispersed territories and paired with single females. Copulation took place between females and males on whose territories they nested. During the nest-building stage, males and females provided nest materials. We observed parental care at two nests. Both sexes participated in incubating and brooding at one nest, whereas only the female incubated and brooded at another nest. During the nestling period, both sexes delivered food (mainly caterpillars, moths, butterflies and crickets) to the nestlings and no helpers were observed. These results suggest that the Tylas Vanga is socially monogamous. We discuss the sex determination based on plumage color and mating system of Tylas Vanga.
The family Vangidae provides one of the most striking examples of adaptive radiation in the Madagascan avifauna, nevertheless, basic information on the breeding biology of many species remains lacking. To examine the breeding system of the endemic Madagascan Chabert's Vanga Leptopterus chabert, we studied the contributions made by adults to nest building, incubating, brooding, and feeding the young at six nests. The study was conducted during November and December in 1999, 2000, and 2005 at Ankarafantsika Strict Nature Reserve. During the nest-building stage, two adults (perhaps a heterosexual pair) delivered nest materials. Two adults participated in incubating and brooding. During the nestling period, several (3–4) adults delivered food (mainly bees, dragonflies, and moths) to the nestlings at two nests. They also mobbed animals that approached the nest. During the post-fledging period, several (3–4) adults fed the fledglings in two family groups. These observations suggest that Chabert's Vangas are cooperative breeders in which several adults feed the young of one brood.
The behavior and parental care of the endemic Red-tailed Vanga Calicalicus madagascariensis were studied in Ranomafana National Park, south-eastern Madagascar, from December 2007 to January 2008. Both sexes are similar in size, but show striking plumage-color dimorphism. The studied breeding pair shared duties in nest building, egg incubation and care of the young, but the male provided more parental care than the female. No helpers were observed at the nest during the study. Incubation lasted about 24 days and the nestling period was 15 days during which time chicks were fed on different types of insects and arthropods (mainly butterflies, spiders and locusts) obtained from the systematic inspection of the branches and leaves. The extensive male investment in the breeding might be due to ensure high rates of nestling growth and to avoid nest predation. To conclude, Red-tailed vanga is a socially monogamous species that exhibits classic biparental care.
I investigated nest-site characteristics affecting the risk of nest predation in the Madagascar Paradise Flycatcher Terpsiphone mutata. Several nest predators have been identified in the study area, and the time of nest predation has also been determined. Two variables, the distance from the nest to the nearest tree and nest visibility, were revealed to have effects on nesting success/failure in this species: nests further from other trees and better concealed by vegetation had higher probabilities of fledging success. Distance from the nearest tree may be a factor affecting predation by a nocturnal, arboreal snake species. On the other hand, nest visibility may affect the probability of being found by diurnal, visually oriented predators. Nest-site characteristics are expected to differ between the nests preyed upon by diurnal and nocturnal predators. Contrary to expectation, no significant difference was observed between the characteristics of nest sites preyed upon in two time categories. The existence of unidentified nest predators, especially diurnal, non-visually oriented species, may conceal the apparent difference in the measurements of nest-site characteristics preyed upon in the two time categories. I suggest that when several predators co-exist in the environment identification of those predators and the time of nest predation are important factors when examining the nest-site characteristics affecting the risk of nest predation.
I examined whether or not the two functions of mixed-species flocks, anti-predator defense and foraging efficiency, differ in seven regularly-participating species between the breeding and non-breeding periods in Madagascan forests. The rate at which I encountered mixed-species flocks was greater in the non-breeding period because six regular species increased their flocking propensity. However, another regular species, the Rufous Vanga, which did not change its flocking propensity was encountered less frequently in mixed flocks in the non-breeding period. During the breeding period, when food was abundant and predators such as raptors were active, anti-predator defense should have been a major concern for flocking birds. Then, mixed-species flocks formed as other species' followed breeding groups of Rufous Vanga as they exhibit a high degree of vigilance and warning against predators. Conversely, during the non-breeding period, when food resources were fewer and conspecific flock sizes were larger, increased foraging efficiency was likely to be the primary concern of flocking birds. Then, those species that utilized similar foraging substrates aggregated to form flocks and did not choose the Rufous Vanga as a foraging partner. Accordingly, the function of avian mixed-species flocks in Madagascar may change seasonally from one of anti-predator defense in the breeding period to one of increased foraging efficiency in the non-breeding period.
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.
The ecology of the Japanese Green Pheasant Phasianus versicolor should be elucidated for proper game bird population management. Individual discrimination is essential to elucidate its sociality. A method for individual discrimination that is reliable, feasible, and minimizes the burden to birds is needed for further research. Each characteristic distinguished by listening to their crow calls in the field seemed to be the clue to discriminate individuality of male pheasants. I visually analyzed sonograms, and observations of the shape, number, and distribution of high sound pressure level (SPL) frequencies distinguished differences of crow calls among birds. Then, I quantitatively analyzed sonograms by performing principal component analysis (PCA) using six parameters. The discriminative acoustic structure of crow calls were selected as six parameters. The crow calls of each bird were clustered closely and did not overlap with those of other birds. These analyses confirmed that there is more inter- than intra-individual variation in the acoustic structure of crow calls. Thus, I demonstrated both visually and quantitatively that the acoustic structure of crow calls discriminates individuality of male Japanese Green Pheasants. Individuality of male pheasants by the acoustic structure of crow calls will promote further research on various aspects of male pheasant society.
Hornbills (Bucerotidae) are large, canopy-dwelling birds in tropical forests that eat various kinds of fruits. We obtained conclusive evidence of the consumption of fallen figs Ficus stricta by Oriental Pied Hornbill Anthracoceros albirostris on the ground in Khao Yai National Park, Thailand, by using camera traps. At least one male Oriental Pied Hornbill was photographed removing sample figs from the ground around a fruiting tree. The use of cameras for the study of birds is generally impractical; however, this method can provide some useful baseline information on the behavior of certain avian species, as demonstrated in this study.
This report describes, for the first time, harmful effects of invasive Yellow Crazy Ants Anoplolepis gracilipes on wild birds in Japan. We observed fledglings of Bull-headed Shrike Lanius bucephalus and Daito White-eye Zosterops japonicus daitoensis caused fatal injuries by ants on the ground on Minami-daito Island. We compared reproductive behaviors of Daito Scops Owl Otus elegans interpositus in a cavity with ants and cavities without ants and found that while reproductive success did not differ between them, parental females in a cavity with ants more frequently interchanged their nest site than those in cavities without ants.
The singing behavior of 17 Grey Thrush Turdus cardis males was studied in a coastal forest in Kanazawa in 1996–1997. Fourteen males made dawn trips from their primary singing areas to a secondary singing area. Three males made multiple daytime trips to these areas. The frequency of trips made by two of the males decreased as breeding progressed in the primary singing area. The third male became to make frequent daytime trips to a secondary singing area after mating with a new female in the secondary area. In the areas where the males had not mated previously, they sang with high Pfs (proportion of full songs in a song bout), whereas in the areas where mating had already occurred Pfs were low. Making frequent trips between singing areas and changing the frequency of full song in song bouts are thought to be parts of a strategy to achieve polygyny.
In the original table, nucleotide diversity (π) during Mar–Jul was described as 0.001756±0.001434SD in error. Correctly, it should be described as 0.001983±0.001557SD. Involving in this correction, long-term effective female population sizes (Nf) during Mar–Jul should be corrected as 4,767 (s=0.28) and 31,984 (s=0.031). Although on 10th line in Abstract and 2nd line of 4th paragraph on 148 page, nucleotide diversity (π) was originally described as 0.0018±0.0014SD, they should be corrected as 0.0020±0.0016SD.