Ikarus Research Articles

Estimation of reaction time for birdsongs and effects of background noise and listener’s age

Recordings of birdsong are often used as an auditory signal for visually-challenged people in public spaces in Japan. To examine the detectability of these sounds, we measured reaction times (RTs) for six types of birdsong: Jay, Cuckoo, Himalayan cuckoo, Japanese grosbeak, Japanese white-eye, and Japanese bush warbler. We presented birdsong stimuli with irregular timing to 20 younger and 20 older participants in combination with silence, white noise, or bandpass noise with a center frequency of 1, 2, or 4 kHz. Regardless of the output levels and participant age, the RT for the Jay, Cuckoo, and Himalayan cuckoo songs was lower than 0.75 sec in the silent condition, and the averaged RT obtained by the younger participants could be estimated on the basis of the duration required to reach a specified sound exposure level for the birdsong stimuli. In the noisy conditions, spectral masking via bandpass noise prolonged the RT, while the bandpass noise with a center frequency higher than that of the birdsong tended to shorten the RT, especially in older participants.

Sequence and organisation of the mitochondrial genome of Japanese Grosbeak (Eophona personata), and the phylogenetic relationships of Fringillidae.

Mitochondrial DNA is a useful molecular marker for phylogenetic and evolutionary analysis. In the current study, we determined the complete mitochondrial genome of Eophona personata, the Japanese Grosbeak, and the phylogenetic relationships of E. personata and 16 other species of the family Fringillidae based on the sequences of 12 mitochondrial protein-coding genes. The mitochondrial genome of E. personata consists of 16,771 base pairs, and contains 13 protein-coding genes, 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and one control region. Analysis of the base composition revealed an A+T bias, a positive AT skew and a negative GC skew. The mitochondrial gene order and arrangement in E. personata was similar to the typical avian mitochondrial gene arrangement. Phylogenetic analysis of 17 species of Fringillidae, based on Bayesian inference and Maximum Likelihood (ML) estimation, showed that the genera Coccothraustes and Hesperiphona are closely related to the genus Eophona, and further showed a sister-group relationship of E. personata and E. migratoria.

Interspecific and annual variation in pre‐dispersal seed predation by a granivorous bird in two East Asian hackberries, Celtis biondii and Celtis sinensis

Pre-dispersal seed predation by granivorous birds has potential to limit fruit removal and subsequent seed dispersal by legitimate avian seed dispersers in bird-dispersed plants, especially when the birds form flocks. We monitored pre-dispersal seed predation by the Japanese grosbeak, Eophona personata, of two bird-dispersed hackberry species (Cannabaceae), Celtis biondii (four trees) and Celtis sinensis (10 trees), for 3 years (2005, 2007 and 2008) in a fragmented forest in temperate Japan. Throughout the 3 years, predation was more intense on C. biondii, which, as a consequence, lost a larger part of its fruit crop. Grosbeaks preferred C. biondii seeds that had a comparatively lower energy content and lower hardness than C. sinensis, suggesting an association between seed hardness and selective foraging by grosbeaks. In C. biondii, intensive predation markedly reduced fruit duration and strongly limited fruit removal by seed dispersers, especially in 2007 and 2008. In C. sinensis, seed dispersers consumed fruits throughout the fruiting seasons in all 3 years. In C. biondii, variation in the timing of grosbeak migration among years was associated with annual variation in this bird's effects on fruit removal. Our results demonstrate that seed predation by flocks of granivorous birds can dramatically disrupt seed dispersal in fleshy-fruited plants and suggest the importance of understanding their flocking behaviour.

Pre-dispersal Seed Predation by a Granivorous Bird, the Masked Grosbeak (Eophona personata), in Two Bird-dispersed Ulmaceae Species

Pre-dispersal seed predation by a granivorous bird, the masked grosbeak (Eophona personata, Fringillidae), was investigated in two bird-dispersed trees, Celtis sinensis and Aphananthe aspera (Ulmaceae). The objectives of this study were to 1) measure direct damage of predation by grosbeaks on plant crops, 2) reveal the temporal pattern of predation within each tree species and its causal factors, and 3) test whether foraging grosbeaks hinder foraging of frugivorous birds, thereby indirectly impacting the reproduction of both tree species. A substantial amount of fruit and seed crop was consumed by grosbeaks (24.3% in Celtis; 55.5% in Aphananthe), and only 17.7% (Celtis) and 16.7% (Aphananthe) were removed by frugivorous birds. At the study site, the grosbeak population size fluctuated greatly during the fruiting seasons of both plant species. As for Celtis, predated seed density also fluctuated temporally, and the local population size of grosbeaks was responsible for predated seed density. In Aphananthe, predation was not fully explained by grosbeak populations or plant phenology, but its peak coincided with that of grosbeak population. These results suggest that pre-dispersal seed predation by granivorous birds can have large negative impacts on the bird-dispersed plants. Changes in local population size of granivorous birds can influence predatation and can affect reproductive success of the bird-dispersed plants available to the birds.

Phylogenetic Comparison of Leucocytozoon spp. from Wild Birds of Japan

Eight species of Japanese birds were found to be infected with Leucocytozoon species using microscopic analysis. We used PCR and sequence analysis of the mitochondrial cytochrome b gene (cyt b) to compare the genetic background among these detected protozoa species. In 20 individuals of 22 samples, a single amplified band was detected from 6 of 8 bird species; 9 Japanese rock ptarmigans (Lagopus mutus japonicus), 4 large-billed crows (Corvus macrorhynchos), 2 carrion crows (C. corone), 2 scops owls (Otus scops), 1 Japanese grosbeak (Eophona personata), and 2 brown-eared bulbuls (Hypsipetes amaurotis), respectively. Phylogenetic analysis based on the partial cyt b sequences revealed that all Leucocytozoon isolates in Japan closely grouped with other Leucocytozoon species previously reported in the literature. Among the Japanese isolates, the phylogenetic tree suggested that L. lovati from the Japanese rock ptarmigan may be basal to the parasites found in other bird species. Our study is the first to identify the molecular relationships among Leucocytozoon parasites in the avifauna of Japan.

ブナ科堅果に対するイカルＥｏｐｈｏｎａ ｐｅｒｓｏｎａｔａの採食行動

Over a 2-day period, 30-70 Grosbeaks Eophona personata were observed feeding on acorns of several fagaceous species (Quercus glauca, Castanopsis cuspidate and its variation C. cuspidate var. sieboldi) in the understory of evergreen broadleaved forest at Funaokayama Hill, Kyoto City. Grosbeaks cracked the cupula and pericarps of acorns with their bills, and fed only on the embryos and cotyledons inside. This feeding behavior on synzoochorous seeds is very similar to that observed when feeding on anemochorous and endozoochorous seeds.

巣箱を利用したフクロウのヒナの標識および育雛時の餌内容

Niigata Prefecture is located along the Japan Sea side of central Honshu, Japan. In this research on Ural Owl, nesting boxes were set out in Japanese black pine (Pinus thunbergii) woodlands along the coast. A total of 50 boxes were provided from 1996 to 2005, set at heights of 2.5 to 3.5 meters, and at intervals of 20-1,000 meters. Twenty of boxes were utilized by breeding Ural Owl. A total of 43 chicks were taken, weighed, banded and returned to their nest. Weight ranged from 240-615 grams. In addition, remains of food were analyzed. During the first week after hatching, remains of Japanese Robin, Blue-and-white Flycatcher and Narcissus Flycatcher were common. These songbirds are on the northern migration just as the chicks hatch out in late April to early May, and are thus readily available in the local area. In addition, these small prey may be easy to the young chicks to digest. Once the chicks have grown to over 400 gr., the size of food items tends to increase, including Whites's Ground Thrush, Starling, Brown-eared Bulbul, Japanese Grosbeak and also Norway rat (Rattus norvegicus). As the chicks grow further doves and pigeons are added. Feeding appears to stop about 5 days before fledging, after which the weight of the chicks drops by 80-100 grams. For the first two weeks after exiting the nest, the fledglings perch on branches within a 30 m radius of the nest, and are fed mostly between midnight and 1200 hrs.

Prevalence of blood parasites in Japanese wild birds.

The prevalence of blood parasites was investigated in 701 Japanese wild birds for 13 years from January, 1988 to March, 2001. Most of the injured or sick birds were caught in the suburbs of Kobe City, Hyogo Prefecture and brought to the zoo for clinical care. Among all the birds examined, 10.6% were infected with hematozoa belonging to three genera as Plasmodium (1.7% of the samples), Haemoproteus (5.1% of the samples) and Leucocytozoon (4.6% of the samples), and two birds (0.29% of the samples), a Japanese grosbeak (Coccothraustes personatus) and a dusky thrush (Turdus naumanni), were infected with microfilariae. Mixed infection with Leucocytozoon sp. and Haemoproteus sp. was observed in 6 individuals of 4 species and that with Leucocytozoon sp. and microfilariae was observed in 2 individuals of 2 species of bird. Relatively high positive rates were 75%(3/4) in the scops owl (Otus scops), 71.4% (10/14) in the ural owl (Strix uralensis), 57.7% (15/26) in the jungle crow (Corvus macrorhynchos), 57.1% (4/7) in the black-tailed gull (Larus crassirostris), 55.6% (5/9) in the brown hawk owl (Ninox scutulata), 41% (16/39) in the carrion crow (Corvus corone) and 24.1% (7/29) in the night heron (Nycticorax nicticorax).

Noteworthy Bird Records from Korea

Several specimens recently added to the bird collection of the Institute of Ornithology, Kyung Hee University, and some live birds obtained from bird shops in Seoul constitute new and noteworthy records. White-winged Crossbill. Loxia leucoptera bifasciata. The first record of this species for Korea is a pair caught from a large flock of Red Crossbills by Lee, Chung-Woo, in a pine forest at Yangsan, Kyongsangnamdo, on 15 February 1969. They are still captive in Seoul. Measurements: bill, 17.9 ( & ) and 17.9 ( 9 ) mm; wing, 90 and 85 mm; tarsus, 15.9 and 15.5 mm; tail, 59 ( & ) mm. Rufous-bellied Pied Woodpecker. Dendrocopos hyperythrus subrufinus. A mounted male specimen, reported to have been collected at Kwang-nung, Kyonggi-do, during 1968-1969, was purchased in a bird shop in Seoul on 20 August 1969. Previously Yamashina (1941:539) reported two males and one female collected at Yong'an'po, Pyongan-pukdo, between 12 May and 3 June 1929. Austin (1948:165) listed the one known Kyonggi-do specimen taken on 18 October 1918. Apparently this is the second specimen of this rare species for South Korea. Measurements: bill, 24.4 mm; wing, 128 mm. Arctic Rosy Finch. Leucosticte arctoa brunneonucha. One netted at Tae'gaewon, Yangju-gun, Kyonggi-do, on 15 November 1968 was kept in a bird shop in Seoul until 30 August 1969. Previously this species was known from North Korea only on the basis of two pairs collected at Man'po, Hamgyongpukdo, on 15 November 1929, and three males and one female collected at Changjin, Hamgyong-namdo in March 1957; in addition, several sightings were reported in the same area during the winter of 1956 and 1957 (Won 1965:370). Red-billed Thrush. Turdus chrysolaus chrysolaus. A single bird in captivity is now in a live bird shop in Seoul. This species is a rare passage migrant through Korea, known previously from four old records. Japanese Grosbeak. Eophona personata magnirostris. Two birds now in a live bird shop in Seoul were captured at Kal'mae Yangju-gun, Kyonggi-do, on 21 April 1968 and in early May 1968, respectively. Measurements: bill, 26.1 and 25.9 mm; wing, 121 and 121 mm; tarsus, 24.6 and 26.9 mm. Though Austin (1948:252) regarded it as a straggler, this species is an uncommon summer resident in northeastern Korea and a rare transient in South Korea. When I was at Tok'chun, North Korea, in August 1945, I saw several dozen birds kept in captivity by local farmers and fed on hemp seed. Several other specimens have been collected recently in Kyonggi-do and near Tong'nae, Pusan (Won 1969:144). Bluethroat. Erithacus svecica weigoldi. A male taken at Po'chun, Kyonggi-do, on 15 May 1969 is apparently the third specimen collected in Korea, although there are several sightings. The first record is of a pair from Suh'sang, Kyonggi-do, on 18 October 1919 (Mori 1920). Recently Fennell and King (1964:243) reported collecting an immature male and a female near Seoul on 24 October 1962 and 10 November 1962, respectively. Between 24 October and 10 November 1962 they also observed a total of six birds on different occasions. Apparently the species is a rare passage migrant through Korea rather than the straggler Austin (1948:212) regarded it.