Ecology and management of moose in northern New England

This study examined three facets of moose ecology in northern New England: impact of moose browsing on forest regeneration, physical characteristics of harvested bull moose, and winter habitat use. Forest regeneration was not considered a major problem in northern Vermont based on stocking levels of commercial tree species. Increasing dominance of softwood species coupled with suppressed growth of hardwoods suggests possible local shifts in composition. Bull moose in Maine had stable body weight and antler spread, and selective harvest of trophy bulls was not apparent over 30 years. Winter locations from aerial surveys indicated that moose preferentially used deciduous/mixed forest proximate to cuts; wetlands and conifer stands were used less. Good physical condition of harvested moose and similarities in habitat use at multiple scales indicates that commercial timber harvesting provides long-term, high quality moose habitat in northern Maine

ANALYSIS OF AGE, BODY WEIGHT AND ANTLER SPREAD OF BULL MOOSE HARVESTED IN MAINE, 1980-2009

Age, field-dressed body weight, and antler spread data collected from 11,566 harvested moose (Alces alces) were analyzed to assess whether temporal change has occurred in the physical characteristics of bull moose from 1980–2009 in Maine. The annual proportion and antler spread of trophy bulls (spread ≥ 137 cm; n = 851) were also analyzed. There was no evidence of a measurable decline in the body weight or antler spread of adult bull moose (≥1.5 years old), similar to findings in Vermont and New Hampshire in a recent >20 year temporal analysis. There was a slight increase in physical characteristics of yearlings that contrasted with the trend in New Hampshire and Vermont where it is speculated that parasitism by winter ticks (Dermacentor albipictus) reduces growth rate and recruitment by yearlings. The proportion of trophy bulls in the harvest declined proportionally ∼26% (9.3 to 6.9%) as harvest increased >2x from 1980–1987 to 2005–2009; however, the mean spread of trophy bulls declined by only 2% (P = 0.002). Additionally, there were no differences (P > 0.05) in the proportion of harvested bulls within each age class between 1980–1987 and 2005–2009, and the relatively stable proportion of mature bulls (>5 years old) in the harvest across time periods (30–44%) does not suggest selective harvest of older, trophy bulls. In the face of the declining regional population, continued monitoring of harvested moose is warranted to best manage the largest and longest harvested population in the northeastern United States

IMPACT OF MOOSE BROWSING ON FOREST REGENERATION IN NORTHEAST VERMONT

Moose (Alces alces) play an important role in the ecological and economic resources of northern New England, a landscape dominated by commercial forests. This study measured the impact of moose browsing on forest regeneration in Wildlife Management Unit E1 in northeastern Vermont where moose density was considered high in the 1990–2000s. We surveyed 37 clearcuts categorized into 4 age classes (3–5, 6–10, 11–15, and 16–20 years old). The stocking rate (stems/plot) of commercial species ranged from 74–76% in the 3–5, 6–10, and 11–15 year age classes, increasing to 86% in the 16–20 year age class. The proportion of plots containing a commercial tree without severe damage was above the accepted threshold stocking level of 40–60% in all age classes. The proportion of plots containing a commercial hardwood stem declined with increasing age class; the opposite occurred with softwood stems indicating a possible shift from hardwood- to softwood-dominated stands from selective browsing pressure. Height of 11–20 year old stems was less than in New Hampshire, indicating that growth was possibly suppressed in Vermont due to higher moose density. Overall, browsing was not considered a major problem based upon stocking rates. Further study is warranted to evaluate whether compensatory growth occurs in response to reduced browsing as forests age and/or moose population density declines

ANALYSIS OF AGE, BODY WEIGHT AND ANTLER SPREAD OF BULL MOOSE HARVESTED IN MAINE, 1980-2009

Age, field-dressed body weight, and antler spread data collected from 11,566 harvested moose (Alces alces) were analyzed to assess whether temporal change has occurred in the physical characteristics of bull moose from 1980–2009 in Maine. The annual proportion and antler spread of trophy bulls (spread ≥ 137 cm; n = 851) were also analyzed. There was no evidence of a measurable decline in the body weight or antler spread of adult bull moose (≥1.5 years old), similar to findings in Vermont and New Hampshire in a recent >20 year temporal analysis. There was a slight increase in physical characteristics of yearlings that contrasted with the trend in New Hampshire and Vermont where it is speculated that parasitism by winter ticks (Dermacentor albipictus) reduces growth rate and recruitment by yearlings. The proportion of trophy bulls in the harvest declined proportionally ∼26% (9.3 to 6.9%) as harvest increased >2x from 1980–1987 to 2005–2009; however, the mean spread of trophy bulls declined by only 2% (P = 0.002). Additionally, there were no differences (P > 0.05) in the proportion of harvested bulls within each age class between 1980–1987 and 2005–2009, and the relatively stable proportion of mature bulls (>5 years old) in the harvest across time periods (30–44%) does not suggest selective harvest of older, trophy bulls. In the face of the declining regional population, continued monitoring of harvested moose is warranted to best manage the largest and longest harvested population in the northeastern United States

USING AERIAL SURVEY OBSERVATIONS TO IDENTIFY WINTER HABITAT USE OF MOOSE IN NORTHERN MAINE

Winter habitat use by moose (Alces alces) is typically comprised of regenerating forest and softwood cover in the northeastern United States, and globally, high winter densities are of concern relative to forest damage. Habitat variables associated with winter locations of moose collected during aerial surveys in Maine in 2011 and 2012 were compared to available habitat at multiple landscape scales. Mixed forest was the most used land cover type at both the location and 5 ha scales (35.1% and 31.3%, respectively). Although regenerating forest habitat was used only in proportion to availability, the proximity to recent clearcuts, light partial cuts, and heavy partial cuts was an important predictor of moose location. The used proportion of coarse habitat variables (i.e., mature and regenerating forest) were similar to those available in each aerial survey block, indicating that heterogeneous and productive moose habitat is widely available across the commercial forest landscape of northern Maine. Moose locations derived from aerial surveys can provide insight about spatial distribution and habitat use across the landscape, identify local density in areas where forest regeneration is of concern, and monitor population responses to commercial forest management practices