Sparrowhawk (Accipiter nisus) Science Article 5
No significant diurnal variation in mean weight was detected in trapped European Sparrowhawks (Accipiter nisus). Weights of males fluctuated rather little through the year, but were highest in March and lowest in August. During the breeding cycle, males lost weight slightly in the prelay/early laying periods, when they were feeding females inpreparation for egg production, and in the late nestling/postfledging periods, when theywere feeding large young. Weights of females fluctuated greatly during the year: they werehighest in May at the time of egg laying and lowest in August at the end of breeding.
I. NEWTON, M. MARQUISS, AND A. VILLAGE, The Auk 100: 344-354. April 1983