Scottish racing pigeons killed by Peregrine Falcons Falco peregrinus: estimation of numbers from ring recoveries and Peregrine daily food intake

摘要

Capsule Daily food intake gave the best indication, with 7-23% of the pigeon population estimated to have been taken.Aims To assess the numbers of Scottish racing pigeons taken by Peregrines, based on the recovery of racing pigeon rings from Peregrine eyries and on the daily food intake (DFI) of Peregrines.Methods The estimate based on ring recoveries was derived from examination of the flight histories of birds whose rings had been recovered during searches at Peregrine eyries. The DFI-based approach involved deriving estimates of the biomass and number of Scottish racing pigeons taken based on the Peregrines' mean daily food requirements, and involved a comprehensive synthesis of available Peregrine dietary data.Results Estimates of the number of Scottish racing pigeons killed by Peregrines, during the 2002 racing season, were a minimum of 3083 from ring recoveries and between 25 283 and 78 385 based on DFI. This represented 1% and 7-23% of the estimated total Scottish loft population respectively. The estimated Peregrine kills based on DFI represented 13-40% of total losses of Scottish racing pigeons to all causes; conversely 60-87% of total losses could not be attributed to Peregrines.Conclusions The recovery of racing pigeon rings from eyries provided only a minimum figure for the total losses of Scottish racing pigeons to Peregrines. Calculations based on Peregrine DFI, however, provided a good indication of the magnitude of Peregrine impact. The DFI technique is constrained by the lack of comprehensive data on relevant parameter values, leading to a broad range of estimates. Further research is encouraged to derive or refine parameter estimates for the DFI calculations in order to refine the estimates of potential kills from this approach.