Influence of Trap Saturation on Estimates of Animal Abundance Based on Catch Per Unit Effort

Estimates of animal abundance based on catch per unit effort may seriously underestimate the abundance when a considerable proportion of traps are released during a trapping period. This paper derives equations which may be used to calculate an index which avoids the bias arising from trap saturation. The model covers situations where several species compete for traps, and where animals may release traps without being captured. Factors other than the species under study may also release traps. Animals which escape after releasing a trap are assumed to do so within a short time compared to the duration of the trapping period.