Breeding biology of the Chinese Sparrow Hawk Accipiter soloensis

Abstract

1. Eight nests of the Chinese Sparrow Hawk Accipter soloensis, breeding in the area of about 60.8 ha in the Kwangneung Forest, Chincheop-myeon, Yangju-gun, Kyeonggi-do, were kept under observation for 42 days from 25 June to 25 August 1974, supplemented by post-breeding census from 27 August to 17 September 1974.
2. Nests were found at an average height of 11.7m, on branches, protruding horizontally from the middle of trunk. They were tray-shaped, with average size of 39.5×34.6cm (the exterior diameter)×17.1cm (height), and average weight 661gm. Eggs were white in color, the average size of 33 eggs from eight nests being 36cm (length)×29.6cm (width), and the average weight 17.2gm.
3. The incubation period of 33 eggs of 8 nests was average 19.5 days. The mean clutch size was 4.1 eggs. Through the incubation period, parents entered the nest 269 times in total and average 28.9 times, per day. The average attendance rate of incubation for non-attendance (off session) was 41.8% in the female and 30.1% in the male.
4. Out of 33 eggs of 8 nests examined, 23 eggs of 6 nests hatched, the hatching rate being 65%.
5. The nestling period of 21 chicks of 5 nests was average 19.4 days, and the average feeding frequency was 31.7 times per day with the highest frequency of 47.3 times on the 14th day after hatching. On the whole, the feeding frequency was slightly higher in the female than in the male.
6. The average time spent by parents on the nest in the feeding period was 37.2%, and the female spent 6.5% more time on the nest than the male. The frequency of attendance gradually decreased as their chicks grew up.
7. The average daily growth rate of chicks were: body length 6.54mm, wing 5.74mm, tail 3.29mm: and the body weight at hatching was 17.83g with average daily growth rate of 6.67g: and the average body weight just before leaving the nest was 142.4gm.
8. The flying success of 19 chicks from 5 nests was 75.8%.
9. The prey for the 8 chicks of 2 nests chosen from each of two different local groups of nests was entirely animal matters. The main food item was the frog which occupied 64.74% of the total food in nest No. 1 of one local group and 75.32% in nest No. 6 of the other local group.
10. The feeding ground was usually paddy fields within average 65m from their nests.
11. The home or feeding range of the pairs of eight nests was average 2.95 ha, and their entire home range was 23.6 ha, which occupied 38.8% of the entire study area.
The average territory size of the eight pairs was 1.05 ha, and their entire territorial area occupied 35% of the entire space of home ranges. Their feeding grounds were outside of their territories.
12. A total of 378 individuals of 26 bird species intruded the territories of Chinese Sparrow Hawk, with the following rate by species: the Great Tit 18.78%, Black-naped Oriole 11.38%, Rollar 9.79%, Chinese Sparrow Hawks 8.73%, Great Spotted Wood-pecker 7.67%, Narcissus Flycatcher 6.35%, and Pied wigtail 5.03%. In 378 territorial defenses 69.28% was by male, 21.37% by female and 9.35% was cooperative defenses by both sexes.
13. The number of Chinese Sparrow Hawks observed in 11 days post-breeding censuses which were made every other day until 17 september was 125, of which adults and young were 39.20% and 60.80% respectively. The final record was a single bird observed on 17 September, and then the Chinese Sparrow Hawks disappeared completely from the study area.
(November 1974)