The use of artificial nest sites erected for starlings in Canterbury,New Zealand

The erection of suitable nest boxes in Canterbury led to local increases in the population of starlings (Sturnus v. vulgaris L), which were enhanced in successive years by the tendency of adults to return to breed in the same box. Boxes with circular entrance holes placed highest in hedgerows were favoured over those with rectangular entrances, those placed lower in hedgerows, or those on either fences or barns. Intraspecific competition for suitable artificial sites occurred frequently, and accounted for 9.7% of all egg and nestling losses. House sparrows (Passer domesticus L) also bred in artificial sites, particularly those previously used by starlings, and local increases in house sparrow populations seemed likely.