BOS J & KOOTEN T VAN (1993) Brood sharing of two female Sparrowhawks Accipiter nisus. LIMOSA 66 (4): 161-163.

A nest of a Sparrowhawk with seven eggs was found near Haren, province of Groningen, NE-Netherlands, on 17 May 1991. No within-clutch variations in pigmentation of eggs were discernable. Subsequent observations revealed two breeding females on the nest, both in adult plumage (female B slightly browner than the grey female A, and therefore presumably two years old). The females were brooding simultaneously (photo). After disturbances, female A returned much quicker to resume breeding than female B (resp. after 5 and 30 min). Only two eggs hatched. Six days after hatching, female B's share in brooding deminished considerably, unlike female A's (fig. 1). Prey deliveries by the adult male were taken to the nest by female B. Both females fed the young, often simultaneously. Female B was last seen 24 days after hatching. The young (male and female) were seen flying 30 days after hatching. Eurasian Sparrowhawk Accipiter nisus

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