Certain lapwing species (Vanellus spp.) breed in agricultural habitats, where they are dependent on particular features of such artificial conditions. The breeding behavior and breeding success of the Grey-headed Lapwing Vanellus cinereus were examined on farmland in central Japan. Thirty-five pairs in 2004 and 42 pairs in 2005 were observed nesting on farmland consisting mainly of rice fields. Nests appeared to be distributed such that aggregations seemed to function as semi-colonies. Farming practices seriously affected breeding success: 33 (42.9%) breeding attempts were prevented during farming cultivation and flooding in spring. In 2004, only 16 (45.7%) pairs produced fledglings, and in 2005 only 14 (33.3%) pairs were successful. Territory size was also a factor affecting breeding success; territory area was positively correlated with the number of fledglings produced per nest. Grey-headed Lapwing parents intensively defended their nests and chicks; furthermore, group defense by multiple adults was also observed frequently. Defensive behavior was mainly directed against avian predators such as crows (Corvus spp.) and raptors, with group defense more frequently against raptors. Group defense was also more likely to occur where nests were close together, and it seemed that such defense was effective in increasing the number of chicks hatched. The breeding success of Grey-headed Lapwing was found to be influenced both by environmental and behavioral factors.
Feeding wild birds in suburban house yards (backyard bird feeding) is an extremely popular activity throughout western countries. In Australia, several studies into the sociological aspects of wildlife feeding have recently been conducted, which report that over a third of suburban householders commonly feed birds on their property. This study was aimed to obtain in-depth sociological information related to backyard bird feeding in both urban and rural settings and to make geographical comparisons. The survey was conducted in August 2003, targeting households in suburbs of Greater Brisbane and localities in the Lockyer Valley, southeast Queensland. The survey confirmed the popularity of backyard feeding both in suburban and rural environments, with the estimated household feeding rate between 36% and 48%. It also involved 43 species of birds being fed. Respondents reported interaction-related reasons and charity-inspired motivations as reasons for starting to feed birds in their backyard. Most feeders regarded the effects of bird feeding as either positive or none despite a lack of authoritative reference sources. The survey consistently showed no significant differences between urban and rural households no matter what question was asked. With now more realistic information that backyard feeding is popular throughout the study area, concerns for the possible effects on recipient animals seem valid. Further research in this area would undoubtedly be useful for relevant agencies in Australia and other countries, including Japan, where this activity is prevalent, to develop more objective and effective policies and guidelines in relation to this complicated and rather controversial activity.
We estimated the breeding origins of 40 Ryukyu Robins Erithacus komadori captured outside their known breeding range on the Sakishima Islands, the southern part of Okinawa-jima, and Kyushu based on 1226 base pairs of the mtDNA control region sequence. This mtDNA region is known to be an ideal genetic marker for estimating the breeding origin of migrating individuals since four genetically distinct groups of breeding populations have previously been identified: three groups of the northern subspecies (E. komadori komadori; Tokara, Oh-shima, and Tokuno-shima groups) and a single group of the southern subspecies (E. komadori namiyei; Okinawa-jima), each of which consists of mostly endemic haplotypes. Among the migrating individuals, Tokara haplotypes dominated (35 individuals). However, three individuals sampled in the Sakishima Islands had an Oh-shima haplotype and two other individuals had Tokuno-shima haplotypes. The migrating individuals from these two populations were not restricted to certain sex or age classes. The populations in Oh-shima and Tokuno-shima were found to be partially migratory and not completely sedentary, with some individuals migrating as far as the Sakishima Islands. Further studies are needed to clarify the relative frequency of migratory individuals in these populations. Additionally, individuals with Okinawa-jima haplotypes were not found outside its breeding range during the nonbreeding season, suggesting that individuals in this population are strictly sedentary.
Previously, we analyzed the regional specialization of ganglion cells in the retina of the Jungle Crow (Corvus macrorhynchos). The present study extends this analysis by determining the numbers and regional distribution of photoreceptor cells and the different colored oil droplets. The numbers of the different colored oil droplets were counted using color microphotographs of fresh retinas. Estimation of the numbers of photoreceptor cells was made using Nissl-stained retinal whole mounts. The estimated total number of photoreceptor cells in the whole mount retina was approximately 17,933,788 (N=4). The peak density of photoreceptor cells was 92,109/mm2 in the central area of the retina, followed by temporal and nasal areas, respectively. Four types of oil droplet were identified on the basis of their color: red, orange, green and translucent. The central retina had a significantly higher population of oil droplets, with a density of 91,202/mm2; this sharply declined at the peripheral retina. The lowest observed density was 13,192/mm2 in the dorsal retina. The densities and sizes of the different colored oil droplets were inversely correlated across the retina. The average sizes of red, orange, green and translucent oil droplets had 6 μm2, 4 μm2, 7 μm2 and 4 μm2, respectively. At the periphery of the retina, the oil droplets were significantly larger than in the central area. The sizes of the different colored oil droplets also varied within the same area. Orange colored oil droplets (33%) were the most common type in the central area, whereas green colored oil droplets were the most frequent in other areas. The results of the present study show that photoreceptor cells and oil droplets are differentially distributed in the retina. From these results, we conclude that the area of high cell density, matched by high neuron densities of the ganglion cell layer, corresponds to the site of acute color vision in the crow retina