Ringing recovery circumstances of small birds of prey

Abstract

A total of 1,696 recovery details for Kestrel, Sparrowhawk, Barn Owl, Tawny Owl and Little Owl ringed during the period 1910-1969 were examined. The bias of the data towards recovery circumstances involving man’s activities and man-made constructions is emphasized. For each species of owl, deaths on roads and railways formed approximately one-tenth of the recoveries over the entire period. While the proportion of each predator killed on railways over the two periods 1910-1945 and 1955-1969 was very similar, the percentage killed on roads had risen five-fold in all Jive species. Collision with moving obstacles (cars and railway engines) was clearly a far greater hazard to the essentially nocturnal owls than to the diurnal predators. In contrast, the proportion of Kestrels and Sparrowhawks colliding with stationary obstructions such as wires, cables, buildings or found ‘concussed’, ‘injured’ or with damaged wings was greater. The Sparrowhawk was prone to become tangled in netting, or collide with windows and greenhouses. Little Owl, Kestrel and Sparrowhawk were the three predators shot, trapped or killed in greatest numbers over the period 1910-1969, such recovery circumstances forming 40%, 41% and 60% of the respective totals. The proportion of all five predators recovered killed by man in the period 1955-1969 was some three-quarters less than during the earlier period 1910-1954. The size of the reduction, however, should be interpreted with caution in view of the increased percentages of predators ‘found dead’ with no cause given. With the exception of Sparrowhawk, numbers of each predator were recovered drowned The affinity of owls for water is noted and it is suggested that young and inexperienced predators, attracted to water to drink and bathe, misjudge the depth, become waterlogged and drown in steep-sided containers such as water-butts, tanks and troughs. While Tawny Owl and Little Owl are the small predators most frequently recovered having become trapped in chimneys, Barn Owl, Kestrel and Sparrow-hawk are more frequently recovered in houses and outbuildings having entered to roost or in pursuit of prey. © 1971 Taylor and Francis Group, LLC.