The Use of Hair Tubes as an Indirect Method for Monitoring Red and Grey Squirrel Populations

Hair tubes were investigated as an indirect means of monitoring red and grey squirrel populations and estimating squirrel densities. Hair tube surveys and live trapping was carried out in six sites, three conifer and three mixed conifer/broadleaf, four of which had both red and grey squirrels resident. Hair tubes detected both red and grey squirrels in these four sites, but no grey squirrels were detected with trapping. Reasons for this are discussed. These results suggest that hair tubes are an effective method for monitoring red and grey squirrel populations and the spread of grey squirrels in different site types. Calibration between hair tube surveys and live trapping was only carried out with red squirrel data. The proportion of tubes visited by red squirrels and densities estimated from live trapping were correlated (r = 0.846, d.f. =6, = 0.034). The generalised linear model, assessing the relationship between the two monitoring methods, revealed a significant relationship (P < 0.001); however, the proportion of used tubes explained very little of the variation within the model (42%). The use of hair tubes as means of estimating squirrel densities is unclear, and further calibration of red squirrel data and initial calibration of grey squirrel data is needed. Laura Finnegan (corresponding author e-mail: lfinnega@tcd.ie), Geoff Hamilton, Julie Perol and