Influence of researcher presence towards nest attendance and breeding of barn owls Tyto javanica javanica

Human disturbance to nesting raptors can influence breeding success, especially during early breeding. This study examined the impact of researcher presence, a relatively low impact human disturbance, on eastern barn owls Tyto javanica javanica during monitoring of 57 nest‐boxes in oil palm plantations in Malaysia over a period of 30 months. We analysed the impact of number of researcher visits on breeding success of barn owls, and recorded the immediate response of barn owls to researcher presence, namely nest‐box return times. We investigated the influence of potential variables (number of visits, visit frequency, breeding stage, habitat, study site, etc.) on barn owl nest survival using a logistic‐exposure model. Additionally, we explored the influence of female return times on hatching success using generalized linear models (GLMs) and used generalized linear mixed models (GLMMs) to analyse variables influencing female return times. A total of 108 breeding attempts were recorded in this study and we found that researcher visits, specifically frequency of visits, had a significant effect on nest survival of barn owls, especially during the incubating stage. Breeding female barn owls showed moderate individual variability in return times, and had shorter return times in mature habitats and when incubating. Longer nest‐box return times also influenced hatching success and we recorded several cases of immediate predation on eggs and young in nests after females were flushed from nest‐boxes by researcher visits. We recommend that researcher presence be minimized with lower frequency and shorter duration of researcher presence during incubation to encourage higher breeding success in barn owls. We also recommend that nest‐box checks be conducted at dusk to ensure nests are not left unattended for extended periods.