Abstract
The predatory behavior of a pair of Bull-headed Shrikes Lanius bucephalus in an early nestling period (the pair had the nestling of about 4-5 days old) was observed at the campus of Chiba University, Chiba Pref., on 22-23 July 1977. The results of the observations were as follows :
(1) During the period of observation prey-attacks by shrikes were observed 195 times (male 149, female 46), of which 137 (male 107, female 30) were successful in capturing prey. A list of prey species is given in Table 1. Of these prey 68% were invertebrates (mainly insects) and 84.1 % of prey animals captured by the male were carried to the nestlings. Feeding of the nestlings was mainly made by the male in the early nestling period.
(2) Three types of prey-attack method by the Shrike were observed. Flying-down method was observed 113 times (57.9 %), fly-catching method 26 times (13.3 %), and chasing-attack method 11 times (5.6%). Percentages of capturing prey were as follows : fly-catching method 92.3%, flying-down method 69.7%, and chasing attack method 9.1 %.
(3) Most frequently used heights of attack-posts were 3-5 and 8 m above the ground. The range of attack-post heights above the ground was 0-16 m (male) and 0-8 m (female).
(4) Of the prey carried to the nestlings 31.3% were from impalements of young sparrows made by the Shrikes. It is very effective for the Shrikes to prey on larger animals such as sparrows, which are impaled and tear off into small pieces to be swallowed by the nestlings. On one day, July 23, 50.7% of the food carried to the nestling by the male was brought from impalements.
(4) Home range of the Bull-headed Shrike pair on July 22-23 (early nestling period) were 2, 500-3, 571 m2 for male and 1, 071-1, 786 m2 for female. Places where the prey was caught by male and female were segregated from each other
