Differential parental investment is the sexual selection process in which females that have acquired an attractive male invest relatively more in his offspring than females that are paired to an unattractive male. However, it is often difficult to distinguish between differential parental investment and compensation for a decrease in parental investment by an attractive mate. Using Barn Swallows Hirundo rustica gutturalis, in which males rarely participate in incubation, we investigated differential incubation investment of females. We made the following four observations: (1) Females participate in 94% of total nest attentiveness (time that eggs were incubated). (2) Female nest attentiveness was positively correlated with the ornamentation of their mates, the size of white spots in the tail, which is a measure of male attractiveness in this population. (3) Male nest attentiveness was not related to male ornaments. (4) Total nest attentiveness was positively correlated with the size of white spots in the tail. These results are consistent with differential parental investment, but not with compensation for a decrease in parental investment by a mate. Therefore, we conclude that female Barn Swallows that have acquired an attractive male invest differentially in incubation.
Foraging behavior and diet of Streaked Shearwaters Calonectris leucomelas rearing chicks on Mikura Island was studied using depth and temperature recording data-loggers and stomach contents. Water mass where birds were foraging was estimated using sea surface temperature experienced by birds. Birds spent 76–96% of their time at sea flying, 4–24% for landing on the water, and made a few (0.5–17.0 per day) shallow (<6 m) dives. Birds made many short (<2 days) and some long (4–10 days) trips. During short trips, birds stayed in the warmer Kuroshio and Kuroshio-Oyashio mixed regions, and fed on Japanese Anchovy Engraulis japonicus, Common Squid Todarodes pacificus and Flying Fish Cypselurus hiraii. During long trips, birds stayed in the colder Oyashio region and fed on anchovy and Pacific Saury Cololabis saira. Birds made more dives during short trips than they did during long trips. Streaked Shearwaters breeding on the island in low—productive Kuroshio water, therefore, adopted dual foraging strategies, and changed their diet and dive frequencies in relation to water masses.
Black-faced Spoonbill Platalea minor is a globally endangered migratory species restricted to East Asia, with a population of only 2,041 birds recorded in 2009. A total of 215 Black-faced Spoonbills has been counted wintering in Japan, and the Yatsushiro Sea, in western Kyushu is one of their main wintering sites (outside Taiwan, where the bulk of the population winters). Construction of a new bridge for the expansion of the Shinkansen (bullet train) network into Kyushu, was planned very close to an important spoonbill loafing site in the Yatsushiro Sea. Changes in the wintering situation were examined during the construction of the Shinkansen bridge (2004-2009) in the Yatsushiro Sea. Moreover, conservation approaches, including the expansion of loafing sites and the use of decoy models, were also evaluated, by conducting habitat expansion and experiments both before and during the construction phase. Initially, the number of Black-faced Spoonbills at the loafing site increased as a consequence of these conservation efforts, but this increase was only temporary and numbers gradually decreased thereafter. Eventually, the birds changed their loafing site to a neighboring river, once construction of the bridge had begun. Fortunately, their numbers in the Yatsushiro Sea have been increasing since changes to the habitat have taken place. Our observations suggest that conserving and maintaining both remaining and potential habitats are very important for the conservation of this endangered species.
The Common Murre Uria aalge is listed as an endangered species in Japan and breeds only on Teuri Island, Hokkaido. The Teuri Island population has decreased from 8,000 birds in 1963 to 19 in 2010. They bred on sea-stack and cliff ledges (open habitat) before 1994, but mostly in cliff caves (closed habitat) after 1994. In closed habitat, the fledging rate was greater and the rate of population decrease was smaller than in open habitat. Restoration actions (decoys and sounds) were effective in attracting murres, but did not enhance the fledging rate sufficiently to raise their population, possibly because of predation by avian predators (Slaty-backed Gulls Larus schistisagus and Jungle Crows Corvus macrorhynchos). Using the fledging rate observed in closed habitat and other demographic parameters found in references, Population Viability Analysis shows that the probability of extinction of the Teuri population within 50 years is 66%. To improve the fledging rate and make the restoration actions more effective, we recommend the control of avian predators.
The Nelicourvi Weaver Ploceus nelicourvi is endemic to Madagascar and information on its breeding biology is scarce and fragmentary. The behavior and parental care of the Nelicourvi Weaver were investigated in Maromizaha Park, eastern Madagascar, from November 2009 to January 2010. We found three nests located 250–700 m apart, suspended 3–10 m above the ground from branches of Nastus spp. (Poaceae) and Tremaorientalis (Ulmaceae) above open areas such as streams or trails. The nests were bulky woven structures each with an extended entrance tunnel (ca. 14 cm long). Over a period of about 12 days, the males built the nest structures and the females contributed the nest lining material. The female alone incubated the eggs for about 15 days, and undertook most of the brooding of the young, with only some assistance from the male. During the nestling period, which lasted 13–25 days, both sexes delivered food (mainly beetles, grasshoppers, caterpillars and occasionally small chameleons) to the nestlings. These results suggest that the Nelicourvi Weaver is a socially monogamous bird.
The energetics of adult Streaked Shearwaters Calonectris leucomelas during the chick-rearing period were examined on Awa Island, Japan, in 2008 and 2009. Basal metabolic rates (BMR) were quantified using an open-flow respirometry system and field metabolic rates (FMR) were quantified using a doubly labelled water (DLW) method. In addition, we used activity loggers to estimate time allocations for different activities at sea. BMR was 0.0124 kJ g–1 h–1 (±0.0153, N=4) on average and corresponded to 54% of the value predicted from allometric equations. FMR was 0.0634 kJ g–1 h–1 (±0.0331, N=3) and was equivalent to 5.1 times BMR, which was higher than values reported for albatrosses (2–4 times BMR). Shearwaters made 50.3 landings a day (±9.8, N=12) and spent 44.8% (±8.0, N=12) of their time sitting on the water. They landed on water approximately twice as often as albatrosses (which have been well-studied using DLW), but they both spent similar proportions of their time on water. Frequent landings at sea, and frequent takeoffs, may generate incremental energetic expenses because of the use of flapping flight; therefore, the Streaked Shearwater's relatively high FMR may be related to its high number of landings.
The appendicular myology of the Scarlet Finch Haematospiza sipahi was found to be primitive in all of the characters known to show variation within the subfamily Carduelinae (Fringillidae). It is the only species of cardueline known so far to exhibit this combination of myological characters, although taxon sampling is still inadequate. Haematospiza provides a reasonable model for the last common ancestor of the Hawaiian radiation of carduelines of the tribe Drepanidini.
We investigated the origin of the iridescent violet-bluish feathers of the adult Jungle Crow, Corvus macrorhynchos, using microscopic and optical techniques. A single layer of melanin granules was found below the surface of the barbules in the feathers of male crows. Although the barbule microstructure was clearly sexually dimorphic, neither the appearance nor the optical measurements were notably different between the sexes, which indicated that the single layer of melanin granules did not contribute to the iridescent color of the feathers. We also found a thin layer, which we refer to as the epicuticle, at the surfaces of the barbules of both male and female feathers, indicating thin-film interference as the most likely cause of the iridescent color. We investigated this possibility by measuring reflection patterns and spectra. Our results suggest that the weak violet-bluish feather color of the feathers of the Jungle Crow is caused by thin-film interface due to the presence of an epicuticle on the feather barbules.
DNA extraction from bird feces has advanced molecular ecological studies, but has been hampered by the enzyme inhibitors remaining in the purified DNA. In this study, flow-through columns with silica membranes were used for DNA purification to remove these inhibitors of Taq DNA polymerase effectively. Here, the purification of mitochondrial and genomic DNA of sufficient quality and quantity to allow PCR amplification of the gene encoding chromo-helicase-DNA binding protein-1 (chd1), located on the avian sex chromosome, is demonstrated. This gene segment allowed sex determination of experimental birds (Cockatiel Nymphicus hollandicus) in a fast, easy, reliable, and accurate manner.
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