AGE-RELATED SURVIVAL IN FEMALE SPARROWHAWKS ACCIPITER-NISUS

Long-term capture-recapture of female Sparrowhawks Accipiter nisus nes ting in three different areas enabled age-related survival rates to be calculated, after correcting for age-related and annual variations in recapture frequency The data provided strong evidence for an improvem ent in survival rates in the first 3 years of life and for a decline i n the last 5-6 years, during a maximum life span of around 10 years. T he decline in survival among older birds was attributed to senescence. At all ages, survival rates were higher in the English area, where br eeding numbers were rapidly increasing, than in two Scottish areas, wh ere breeding numbers were stable or declining. The precise pattern of change in survival rates with age may vary between areas, according to prevailing circumstances.