Woodfordia floribunda has ornithophilous flowers suited for pollination by passerine birds. The flowering phase, when the shrub is leafless, and the red nectariferous flowers attract various passerine bird species. The visiting birds probe the flowers legitimately to collect nectar and in so doing, their beaks and foreheads strike against the sex organs effecting pollination. Furthermore, the birds move frequently between different shrubs in search of more nectar and in the process cross-pollination is promoted. Hand-pollination tests indicate that this plant species sets fruit through self and cross-pollination and the same is confirmed by very high natural fruit set rate. Bees and butterflies also visit the flowers for pollen and/or nectar but their role in pollination is almost negligible. The fruit is a capsule, with numerous tiny, light seeds, and is enclosed by a persistent membranous calyx. As the calyx is red, it attracts passerine birds during the fruiting phase. Some passerine birds involved in pollination during the flowering phase are also attracted to the growing fruits and feed on the seeds when the latter are mature and ready for dehiscence. In this way, such birds act as seed dispersers. Therefore, W. floribunda is adapted both for pollination and for seed dispersal by passerine birds.
We satellite-tracked the migration of two adult and one young Honey-buzzards Pernis apivorus between the Japanese breeding ground and Southeast Asia. In autumn migration, the two adults (A1 and A2) migrated across the East China Sea, then through China, the Indochina and Malay Peninsula, and Sumatra. After Sumatra, A1 arrived in Java for the winter, while A2 moved up through Borneo and reached Mindanao, the Philippines. The young honey-buzzard moved along the coast of the South China Sea to reach the Malay Peninsula for the winter. In spring migration, A1 went up the Malay Peninsula, and then took a route different from its autumn route, moving up inland China, down to North and South Korea, and arrived at the previous breeding site in Japan. A2 followed the autumn route and reached a stopover site in Cambodia. After an undetermined radio silence, it was rediscovered back at its breeding area in Japan. The young stayed at the wintering site, making no apparent effort to get back to the breeding area. The sample size is limited, but these results suggest that the migration of Honey-buzzards is remarkably convoluted and varies considerably with bird age and season.
The effects of a severe typhoon (9918 Bart) on a bird community in a warm temperate forest, southern Japan, in 1999, were investigated. The total abundance and number of species showed clear seasonality in normal years, and were higher during winter mostly due to the influx of winter visitor species. The composition of dietary and foraging guilds also changed among seasons. Among the dietary guilds, frugivores/granivores and omnivores increased in winter, whereas insectivores decreased in winter. As for the foraging guilds, forest interior- or edge-dependent species increased in winter, whereas generalists remained constant. Therefore, I examined the effects of typhoon 9918 Bart in winter and in summer, comparing the data sets from three years before and two years after its passage. In the first winter after the typhoon, the abundance of birds was significantly lower than in all three control years, however it recovered to the same level as the control years in the second winter. In contrast, in both the first and second summer after the typhoon, bird abundance was significantly higher than in the control years. The effects of the typhoon also differed among the dietary and foraging guilds. The winter dominant frugivores/granivores were fewer in the first winter leading to a decrease in total bird abundance in that season, whereas the increase in omnivores and insectivores resulted in the increased total bird abundance in summer. The reduction in forest interior-dependent species led to the lower total abundance in winter, and the increase in forest edge-dependent species may have led to the increase in total bird abundance both in winter and in summer. These different responses among different foraging and dietary guilds affected total bird abundance in concert. The disturbance event (typhoon) appeared to cause opposing effects on total bird abundance in winter and in summer.
Parasites were studied qualitatively and quantitatively from the blood of 859 birds mist-netted between 1998 and 2003 in Singapore, Peninsular Malaysia (Cameron Highland, Fraser's Hill, Pasoh and Johor), East Malaysia (Sarawak) and Indonesia (Java). The total prevalence and relative abundance of haemoparasitic infection in the birds were evaluated by location (study area) and habitat type (e.g. primary forest). Over 50% of the examined bird species were parasitized by more than one species, in some up to five. The greater research effort was invested in Fraser and Cameron, yielding the largest numbers of birds (340) and species (55), and contributing the largest share of the recovered haemoparasites. The Fraser's Hill collection yielded the highest prevalence. The prevalence in Cameron Highlands's birds varied annually. In the latter area, Leucocytozoon infection was consistently more prevalent than Haemoproteus. In the remaining study areas, the overall prevalence was considerably lower, usually not exceeding 20% and predominated by Haemoproteus. The overall infection in Pasoh and Singapore did not exceed 6%. In the rest of the study areas Leucocytozoon prevalence was 0–3%. Our prevalence data seemed to fluctuate between years, but their magnitude could be evaluated without multi-annual studies. No particular preference in the efficacy of transmission could be demonstrated for either primary or secondary forests.
The distribution of Sanderling Calidris alba, and inter-tidal infaunal biomass was monitored over an annual cycle. In addition, the feeding behavior and fecal contents of Sanderling were studied in order to examine the relationship between the seasonal distribution of Sanderling and prey availability at Kujukuri Beach, Chiba Prefecture. Sanderling were observed on the beach from August through winter to May with an estimated total number of ca. 600 birds consistently being recorded from September to May. The numbers were supplemented by passage migrants with peaks in August, late January/early February and April. Direct observation, prey availability and fecal evidence indicated that Sanderling fed mainly on the surf clam Donax (Chion) semigranosus, the isopod Excirolana chiltoni and the mysid Archaeomysis vulgaris as well as insects. During winter (December to February) when the densities of E. chiltoni and A. vulgaris markedly decreased, Sanderling distribution was positively correlated (P<0.01) with the distribution of D. semigranosus, which formed its main prey during this period. Sanderling were observed to direct their attacks on D. semigranosus at the surf clam's muscular foot and the shell part was subsequently discarded. We conclude that Kujukuri Beach is important both as an over-wintering site and as a temporary stopover site for migrant Sanderling and that over-wintering Sanderling respond to the seasonal variation in the abundance of their main prey.
I examined both natural and artificial nests to investigate the relationship between nest-site characteristics and the risk of nest predation in a grassland-nesting passerine, the Black-browed Reed Warbler Acrocephalus bistrigiceps. Although an early-season artificial nest experiment did not detect significant effects because of infrequent predation, a late-season experiment indicated that nests were more likely to be depredated at sites where Phragmites reeds were highly dominant. Stems of the common reed P. communis are extremely thick and strong compared to those of other grasses. The results suggest that strong stems aid the effective search and attack on bird nests by predators. Among natural nests, however, predation was not explained by any nest-site characteristics, suggesting that the activity of parents and nestlings masked the effect of plant strength on nest predation.
The Greater White-fronted Goose Anser albifrons has recently begun to winter at Lake Otomonuma (Akita Prefecture), a migratory stop-over site located 180 km northwest of its main wintering site at Lake Izunuma–Uchinuma (Miyagi Prefecture), in northern Honshu, Japan. Data collected over a 17-year period (from 1987/1988 to 2003/2004) have allowed us to analyze factors influencing the large-scale redistribution of this species. The number of geese in Akita increased during November and December, but decreased in January. The number of geese wintering in Akita from November to December was not correlated with the number wintering in Miyagi; therefore, migration from the breeding area or from northern staging sites seems to have caused the population to increase in Akita in December. The population in Akita decreases with low temperatures in January; however, the decrease in Akita was not correlated directly with an increase in Miyagi from December to January as the geese also visit other more southerly areas in addition to Miyagi. In fact, we found no significant correlation between the size of the goose population in Akita and climatic conditions during November and December. Our analysis demonstrated that the use of Akita by Greater White-fronted Goose in winter was attributed to density-independent effects regardless of the population fluctuation in Miyagi from November to December, and to severe weather conditions in January forcing the geese to move from Akita to a southern refuge.
We compared foraging behavior of Bufflehead (Bucephala albeola Linnaeus) and Common Loon (Gavia immer Brünnich) on eight lakes in harvested and unharvested boreal mixedwood forest in northern Alberta, Canada. For one summer before (1996) and two summers after (1997, 1998) forest harvesting around three of the eight lakes, we recorded the duration of Bufflehead and Common Loon dives. After logging, forested buffer strips 100 m-wide separated cut-blocks from lakes (‘harvested lakes’). ‘Unharvested lakes’ were surrounded by ≥450 m of undisturbed forest throughout the study. There were no detectable differences in dive duration between harvested and unharvested lakes for Bufflehead or Common Loon. Correlations between environmental variables (water clarity, fish biomass, depth) and the duration of Common Loon dives were not significant. However, the duration of Bufflehead dives differed between lakes, unrelated to forest harvesting. The duration of Bufflehead dives was negatively correlated with water clarity but was not significantly correlated with fish biomass. While our study shows that the foraging behavior of Buffleheads was affected by lake conditions, the utility of aquatic birds as indicators of the effects of forestry on western boreal lakes remains unproven.