Abstract
Diurnal change of activity and social behaviour of Latham's Snipe Gallinago hardwickii was observed at Iizuna and Hotchi, Nagano Prefecture, Central Japan. Diurnal change of calls and flight displays were observed for 24 consecutive hours. The movements of Latham's Snipe with radio transmitters were monitored and their activities were analyzed by actogram. Latham's Snips arrived in the early April and stayed until the end of July in the study area. Seven birds were captured and radio transmitters were attached to them. Most of them stayed in the study area for more than one month. Vocal activities such as flight displays and ground calls were most active just before sun rise and just after sun set. On some days, other peaks of vocal activities were also observed around midnight or in the daytime. Flight display consisted of a circular flight and powerful dives accompanied by rather harsh notes and flapping of wings. The flight displays in the morning and evening were aggressive and each bird circled in a small area, rarely overlapping the flight display area of other birds. Flight display area were concentrated at a marsh. A concentric structure of flight display areas from the center to the peripheral area was formed, whereas daytime flight displays were less aggressive and communal flight displays were often obseved with a group of adjacent members circling together in a wide area. Analysis of actogram showed Latham's Snipes on the ground were most active in the morning and evening, and more active in the daytime than at night. In general, their home range on the ground was larger than the flight display areas and they overlaped each other. They did not defend their feeding area. Two nests found at the edge of marsh, were located outside the flight display areas. Incubations were carried out by one bird. The bird did not call or flight display. From these facts, it was concluded that the birds displaying actively by aerial performance were males and the bird incubating was a female. It was discussed that the flight display area of Latham's Snipe could be regarded as an arena formed in the air and the mating system of Latham's Snipe a lek like system.
