TIMBER HARVEST AND CALVING SITE FIDELITY OF MOOSE IN NORTHWESTERN ONTARIO

Abstract

Disturbance, whether natural or human, can limit the ability of individuals to maintain occupancy of preferred habitats over time. If suitable habitat provides for the successful rearing of offspring, then an individual may return to use the same area in subsequent years. Loss of that habitat may have important consequences. To evaluate the effects of timer harvest on moose (Alces alces) populations, 60 adult females have been repeatedly captured and fitted with GPS radio collars in northwestern Ontario annually since 1995. To determine if cow moose return to the same area in subsequent years to give birth, location data collected from the collared moose were used to delineate potential calving sites from 1995 - 98. Areas where distances between successive GPS locations (i.e., distances traveled) were less than 100m for a period of at least 3 consecutive days in May of each year were identified as potential calving areas. The UTM coordinates of the locations comprising each potential calving area were averaged to obtain a central point. Linear distances between these pointes from year to year were used as a measure of site fidelity for individual cow moose. Distances between consecutive calving sites differed between 2 timber harvesting systems that produce different habitat disturbance patterns in the study area. Cow moose that inhabited the 2 areas harvested using small, dispersed patch cuts (80-130 ha) had average distances between annual sites of 2.82 ± 2.37 km (n = 24) and 2.02 ± 1.68 km (n = 11), whereas collared moose in an area that has been contiguously and progressively clear cut averaged 4.87 ± 3.62 km (n = 12) in successive years. These differences are attributable to habitat heterogeneity in the size and distribution of cut and uncut patches within harvested areas and, possibly, differences in the density of suitable calving sites. Collared moose showed a lot of individual variability in distances between consecutive calving sites across both types of logged landscapes and among years. The minimum distance between consecutive sites was only 56 m, and the maximum distance was 12.32 km. Changes in distributions of logging activity, predators, conspecifics, and climate could all contribute to this variability. Regardless of timber harvesting effects, distances between successive calving sites of cows that successfully raised a calf (2.60 ± 2.29 km, n = 30) were significantly less than distances of cows that were not observed with a calf following parturition (4.13 ± 3.04 km, n = 17). Thus, it appears that calving site fidelity of cow moose could be related to past reproductive success. Identification of the specific characteristics that contribute to calving site fidelity, as well as an analysis of the distribution and abundance of potential sites in different landscapes, are needed if preferred calving habitat is to be protected in timber management plans.