Adaptability in moose (Alces alces L) : habitat selection in two landscapes in Newfoundland, Canada

Abstract

Moose (Alces alces [L.]) exist circumglobally and in a vast array of different habitats. I explore differences in habitat selection in relation to differences in availability of forest stands by habitat type and number of foraging patches, and variation in quality of a winter forage item, balsam fir (Abies balsamea [L.] Mill.), used by moose in Gros Morne National Park, Newfoundland and Labrador, Canada. Adult female moose collared in 1997-1998 occupied two landscapes, the Gulf of St. Lawrence Coastal Plain ecoregion (lowlands) and the Long Range Barrens ecoregion (highlands). They followed three landscape-use strategies: year-round residence in the lowlands (n = 5), year-round residence in the highlands (n = 5), and migration from lowlands in winter to the highlands in summer (n = 2). Habitat selection at the stand scale was calculated as the likelihood of selecting a habitat type, based on its availability estimated from classification of SPOT-5 satellite imagery and on moose location data from Global Positioning System (GPS) collars, used to calculate home ranges, core-use areas and foraging patches. There was no difference in habitat selection between migrants and residents either in the lowlands in winter or in the highlands in summer. The summer season, identified as the period of higher rate of movement compared to the winter, was shorter for migrants (median 166 days) than for moose occupying the highlands (174 days) and the lowlands (173days). Foraging patches were arbitrarily defined as areas where a minimum of three consecutive GPS locations < 24 h apart occurred with distances between them of < 50 m. Straight-line distances between successive locations and between foraging patches over weekly and seasonal periods did not differ among the three landscape-use strategies in winter or in summer. Distances travelled were lower in winter than in summer and the number of foraging patches relative to the amount of forested area was higher in the highlands. Chemical analysis of terminal and lateral branches of balsam fir, collected in July 2010, was used as a surrogate for identifying site richness in foraging patches and as a means of identifying forage quality. Lateral and terminal branches had a higher carbon-to-nitrogen ratio in the lowlands, including significant variation in quality by habitat type, compared to the highlands, where variation did not occur by habitat and carbon-to-nitrogen ratio was significantly lower. This outcome suggests the lowlands offer lower quality forage items and lower average site richness compared to the highlands. The migration strategy likely evolved for moose to cope with less available forage during winter in the highlands when snow is very deep.