Impact of visitor disturbance on Atlantic puffins and Arctic terns breeding on the Isle of May: final report to Scottish Natural Heritage

Encouraging human access to wildlife areas is a key element of generating public support for nature conservation, and has educational and economic benefits. However, human presence also causes disturbance which has a range of negative effects on wildlife. To resolve this conflict successfully, conservation practitioners need to devise appropriate visitor access strategies. This requires quantifying the impact of different visitor regimes on the population of interest. The aim of this study was to quantify the impact of visitor disturbance on breeding success of two seabird species, Atlantic puffin (Fratercula arctica) and Arctic tern (Sterna paradisaea) on the Isle of May NNR. To achieve this we developed a model estimating the disturbance effect on breeding success, mediated via changes in chick provisioning rates and chick body mass. The model compared peak chick mass and survival probability (as a measure of breeding success) in the absence of visitors with those in the presence of visitors under different scenarios of varying visitor numbers, and visit durations and timings.