Leucocytozoon toddiin British sparrowhawksAccipiter nisus: patterns of infection in nestlings

Leucocytozoon infection was studied in nestlings of a population of sparrowhawks in England. Infection became apparent in nestlings from around 12 days of age, and increased rapidly to around 29% in the oldest nestlings observed. The infection was much commoner at nest sites on the London Clay than on neighbouring loams, sands and gravel, and was commoner in nestlings from small broods than those from large broods. There was no firm evidence that the infection caused short-term mortality or reduced long-term longevity. Evidence suggesting that the vector is more likely to be a Culicoides sp. than a Simulium sp. includes (1) only slight reduction of infection rates with increasing distance from running water and (2) higher infection rates on the London Clay, where exposure to Culicoides is likely to be relatively higher than on the well-drained sands and gravels.