Temporal changes in the breeding ecology of European Turtle Doves Streptopelia turtur in Britain, and implications for conservation.
The migratory European Turtle Dove Streptopelia turtur has undergone a 69% decline in population size and a 25% contraction in breeding range in Britain over the last 30 years. An investigation of the breeding ecology of this summer visitor was undertaken in 1998-2000 at two study sites in East Anglia, England. The only previous study of Turtle Dove reproduction in Britain provided pre-decline data for comparison with the current situation in a modern agricultural environment. Territory sizes ranged from 1.91 to 3.08 ha, were established in areas with scrub, hedges and woodland and contained less cropped land than expected from its availability. The majority of nests were sited 1-3 m above ground level within thorny bushes, particularly Hawthorn Crataegus monogyna. Nests found by radiotelemetry were significantly higher above ground level and were found in greater numbers than expected in woodland and coniferous trees than those found by cold searching, which were lower and found predominantly in hedges and thorny bushes. Turtle Dove nest success rate averaged 53% during incubation and 65% during the nestling stage, so that only 35% of nests successfully produced young. A comparison with data collected during the 1960s showed that Turtle Doves today have a shorter breeding season and consequently produce about half the number of clutches and young per pair than formerly. A simple simulation model suggested that the reduction in productivity alone would lead to a population decline of 17% per annum. This study suggests that the recovery of Turtle Doves in Britain is dependent upon the provision and sympathetic management of nesting and foraging habitats. The current arrangements for set-aside and agri-environmental schemes provide the framework for delivering these requirements.