SOCIAL BEHAVIOUR AND DISPERSION OF THE BLACKSHOULDERED KITE

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Abstract
Mendelsohn, J. M. 1983. Social behaviour and dispersion of the Blackshouldered Kite. Ostrich 54: l–18. Colour-marked Blackshouldered Kites Elanus caeruleus were studied at Settlers in the Springbok Flats, South Africa. Males usually established territories where females joined them as mates after moving around between territorial males. There were always more resident males than females. Territories were exclusive nesting and hunting areas. The number of territories decreased, but mean territory size increased during the study. Unpaired kites held smaller territories than other residents. Males usually established territories when occupied areas fell vacant, but females usually paired when most other pairs were starting to breed. Both sexes abandoned territories when food supply was poor. Unpaired males deserted more frequently and had longer temporary absences than paired or breeding males. Most kites (86%) were resident for periods of less than 100 days. Females spent either most or very little of their time breeding. The longer males were resident, the greater the proportion of their time spent paired and breeding. Population size varied between 19 and 35 kites ([Xbar]=26); about 13% of the population was replaced each half-month. More nomads visited the study area when feeding and breeding conditions were good. After deserting territories, males usually became nomads while females probably moved to new territories. The social organization of Blackshouldered Kites is discussed with reference to food supply (Mendelsohn 1982), population dynamics, and breeding biology (Mendelsohn 1981).