SURVIVAL IN AN INTENSIVELY TRAPPED MARTEN POPULATION IN MAINE

Marten (Martes americana) are susceptible to overharvesting, and fores try practices may compound this problem by reducing habitat quality an d increasing accessibility of trappers via forest roads. From May 1989 through December 1991, we estimated age- and sex-specific survival of marten in a logged area with road access. We tested for age- and sex- specific differences in survival, combined estimates of survival with published natality rates to evaluate whether harvests were sustainable , and simulated population response to management options. Trapping ac counted for 90% of all documented mortalities (n = 49) among 38 radio- collared female (26 ad, 12 juv) and 36 radio-collared male (24 ad, 12 juv) marten. Most (93%) trapping-caused mortality occurred during the first 14 days of the season, during which vulnerability of adult femal es to trapping was 1.45-1.75 times less (P < 0.01) than for other age- sex classes. Survival from 1 May to 15 December was higher (P = 0.03) for adult females (0.39) than adult males (0.12). Harvests of female m arten were not sustainable, and shortening the trapping season from 6 to 2 weeks would be ineffective at achieving a finite rate of populati on change (lambda) greater-than-or-equal-to 1.0. Unless immigration co mpensated for emigration and trapper-caused mortality, we estimated th at survival of females would need to nearly double to sustain the popu lation. Access by trappers via logging roads increases the potential f or declines in marten populations. Regulations to reduce trapping-caus ed mortality may be needed to maintain viable marten populations in la ndscapes with extensive forest harvesting and intensive trapping.