The status of breeding Barn Owls Tyto alba in the United Kingdom 1995-97

A national survey of breeding Barn Owls was undertaken between 1995 and 199 7 using intensive fieldwork methods within a stratified sample of 1100 2 x 2-km survey squares selected at random from those available. Each year, fie ldwork was divided into two sessions: one to locate potential nest-sites (w inter session) and one to determine occupancy of these sites (summer sessio n). Fieldworkers spent an average of 30 hours on fieldwork within each surv ey square. The survey produced national population estimates of 2830 (95% c onfidence intervals: 1952-3761) breeding pairs for 1995, 3967 (95% CI: 2785 -5252) for 1996 and 3951 (95% CI: 2769-5214) for 1997. Analysis taking acco unt of the poor coverage in certain regions of high Barn Owl density in 199 5 suggests that a population estimate of 3480 would be more accurate for th at year. Regional and temporal variations in estimates were examined and in terpreted in relation to Barn Owl productivity and ecology. Validation of f ieldwork efficiency was carried out within a random selection of the availa ble survey tetrads, demonstrating that fieldworkers achieved a high degree of survey reliability. This paper provides a baseline population estimate a nd standardized, repeatable methods, allowing future population changes to be monitored effectively.