EVIDENCE OF CARRYING CAPACITY EFFECTS IN NEWFOUNDLAND MOOSE

Abstract

Newfoundland moose (Alces alces americana) increased following 1904, the year of successful introduction, to peak numbers in 1958. The population subsequently decreased to record low numbers by 1973, when an area-quota management system was instituted throughout the island (112,000 km²) in 38 moose management areas, in part, to respond to issues related to habitat and accessibility for hunting. Subsequent quota-management manipulations permitted the islandwide population to increase in accessible areas to record high numbers by 1986, after which populations again decreased, to a 1999 estimate of 125,000 animals (post-hunt). We hypothesise that, unlike most studied irruptions of cervid populations, moose populations in Newfoundland, and subsequently habitat carrying capacity (K), decreased on inaccessible range following 1958 to very low density, from which both have never recovered. Decreases in relative numbers of young moose seen while hunting and during winter classifications are consistent with increases in the number of moose seen during increase phases during 1966–99. These observations are less obvious for less accessible management areas. We explore other recruitment and density relationships as they have been developed in association with our estimate of K in moose for Newfoundland. We illustrate that, although some decrease in moose numbers following 1958 and 1986 was the result of management, changes to population size and to K also resulted in reduction in productivity, such that density dependence explains > 10% and up to 76% of hunter-observed recruitment.