BEAVER POPULATIONS AND THEIR RELATION TO WETLAND HABITAT AND BREEDINGWATERFOWL IN MAINE

The influence of beaver (Castor canadensis) trapping on beaver and wat erfowl densities and wetland habitat is not well understood, and this information is needed by managers trying to balance beaver densities a nd harvest and complaints of nuisance beaver with the abundance of wet lands and waterfowl. During 1988-92 in south-central Maine, we determi ned the density of braver colonies and beaver harvest, wetland charact eristics, and density of breeding pairs of waterfowl on a 111-km(2) si te recently closed to beaver trapping and a similar site open to trapp ing. Density of beaver colonies increased from 0.15 to 0.32/km(2) (113 %) on the untrapped site but changed little (0.19-0.20/km(2)) on the t rapped site. The number of beaver dams maintained by beaver and the de nsity of beaver colonies were correlated on the untrapped site (r = 0. 99, n = 4, P = 0.009) but not on the trapped site (r = -0.18, n = 4, P = 0.820). Number of wetlands was correlated with the density of beave r colonies during 1989-92 on the untrapped site (r = 0.92, n = 4, P = 0.081) but not on the trapped site (r = -0.13, n = 4, P = 0.875). Tota l surface area of water on the untrapped site increased from 115 to 15 8 ha (36%); surface area of water remained stable on the trapped area. Species of waterfowl that increased on the untrapped site included Ca nada geese (Branta canadensis) (4-9/100 km(2)), hooded mergansers (Lop hodytes cucullatus) (23-29/100 km(2)), and mallards (Anas platyrhyncho s) (7-12/100 km(2)). Numbers of wetlands used by pairs of each species of waterfowl increased on the untrapped site. Overall, a greater than or equal to 1-year closure of beaver trapping is sufficient to increa se the density of beaver colonies, whereas a 2-3 year closure is neces sary to increase wetland habitat. More than 3-4 years may be required to begin influencing the density of waterfowl and number of wetlands u sed by waterfowl.