A short note on the territorial observations of Japanese Turdus cardis

Abstract

1. Eight observations were made on the territorial behaviour of Turdus cardis during April and September, 1966, at Gotemba, Shizuoka Prefecture, 540-570m of altitude at the foot of Mt. Fuji.
2. Territories were established in relatively young chryptomeria-'hinoki' plantations and more preferably around farm house with cultivated or grassy foreyard and a small plantation often with patch of broad leaved trees.
3. Total census area covered about 49 ha, but 34 ha if non-utilized open paddies are excluded. Almost whole utilizable area was divided into territories at least 25 in number.
4. Average territory size was estimated roughly as about 1.5 ha; the smallest may be 0.75 ha and there was exceptionally large one of about 4.7 ha, though there might have existed another territory within it, and birds of two other territories were observed to invade in it for feeding.
5. A few territories were isolated by a stretch of paddy fields, but their owners were seen to fly across it (more or less 100m) to get into grouped territorial area.
6. In one case, a non-mated male maintained a small territory of about 0.4 ha through the season and continued to sing. There were about 25 breeding males and at least 5 non-mated ones, which were found along the edge of ill-grown dense chryptomeria wood and these flew to and fro singing a short excited song.
7. The following territorial defense and fightings by two or three males were observed in the early season: a) two males exchange low ground calls to confirm territorial boundary, keeping a certain buffer distance. b) Non-mated males sing a low excited aggressive song in which mimics of other birds such as Parus and Alauda are mixed. This was sang with forward posture against the oponent which is mated. This song is sometimes mixed with fragment of true song. c) The mated oponent males may sit against it a few meters apart or sing the true song within its territory, but never attacks while the other is singing the aggressive song. However, as soon as the latter finished or showed intention movement, it was chased by the mated oponent. d) A keen 'tsee' note is issued by excited competitive males to advertise their own movement. A female may also issue it probably as an alarm sign for fledged young nearby.
8. Although the census during the fledging period was not enough, fledged young were observed in 11 of about 25 territories, and fledged brood sizes were: 5 young (two), 4 young (one), 3 young (five), 2 young (two), with the average of 3.5 young per territory.
9. In two territories invasion of second male occurred in later season and competition was observed. It might happen that the female of the first male is remated with the new male as the aggressiveness of the former is weakened. This may make the second brood of the female effective.
10. The song frequency dropped as the breeding advanced, but was irregularly rivived and continued as the mean of post-breeding territorial maintenance. On September 6, almost all adults had left the breeding area, leaving some grown young.