Inferring red squirrel (Sciurus vulgaris) absence with hair tubes surveys: a sampling protocol

摘要: Hair tubes are often used to monitor red squirrel in fragmented landscapes, where presence/absence data gathered determine its distribution and factors affecting it. Despite many applications evaluation of this technique for density estimation, the reliability absence has been overlooked, as no rigorous statistical estimate attempted both on survey duration absences. Accurate determination a (e.g. how visits should be carried out consider species absent rather than non-detected) will affect total costs number monitored sites; moreover, false absences bias estimates. By applying some recently developed occupancy models, we estimated detection probability sampling size required infer absence. Application analysis protocol allows at reasonable cost thus evaluate dataset.