The role of diseases and parasites is occasionally of some significance to 

 mammals in Maine. The most important example is the brain worm parasite 

 ( Paraelaphostrongylus tenuis ) and its effect on moose populations. The 

 natural host of the brain worm is the white-tailed deer, in which it 

 apparently causes no harm. However, it is also capable of infecting moose 

 when it is ingested with its alternate host, one of several species of 

 molluscs. The brain worm damages the central nervous system, sometimes 

 killing moose outright but also affecting their behavior, which subjects them 

 to other forms of mortality (such as roadkills, poachers, and accidents). 

 Gilbert (1974) studied the incidence of brain worm in Maine moose and found 

 that where moose occurred with high deer populations the rate of infection was 

 high enough to reduce moose populations significantly. The incidence of brain 

 worm in a sample of illegally killed moose was 50%, 80%, and 64% in Wildlife 

 Management Units 6, 7, and 8, respectively. 



Other diseases and parasites that are important to mammals are rabies virus in 

 carnivores (fox, skunk, coyote, bobcat) and sarcoptic mange caused by 

 mites , ( Acari ) . These may become manifest when host populations are high 

 because they are transmitted more easily then and overpopulation often results 

 in less vigorous animals that are more susceptible to infection (see below for 

 incidence of rabies in the characterization area). 



Human Factors 



People affect mammals directly, through mortality factors such as hunting, 

 trapping, roadkills and environmental contaminants, and by affecting the 

 amount and quality of habitat that is available. In any situation involving 

 habitat change some species will be adversely affected, and others will 

 benefit. 



The major land uses influencing mammal habitat in the characterization area 

 are logging, agriculture, and development (housing, industrial, commercial, 

 highways). The latter has the most significant impact because the habitat 

 loss is permanent and developed areas support very few mammal species (figure 

 17-2). On the basis of Wildlife Management Units, developed land is most 

 abundant in the southwestern coastal regions. In Wildlife Management Unit 8, 

 13% of the land falls in this category, compared to 6% of Unit 7 and only 2% 

 of Unit 6 (table 17-2). Species of mammals that can be expected to benefit 

 from further urbanization include some species of bats, gray squirrels, Norway 

 rats, house mice, and perhaps raccoons (figure 17-2). Additional species that 

 may benefit from suburban or rural developments (farms) include foxes, skunks, 

 chipmunks, short-tailed shrews, woodchucks, meadow voles, and coyotes. Most 

 other species, if not all, will be adversely affected by land development. 



Although little can be done to slow the rate of urbanization, steps can be 

 taken to mitigate its environmental effects. Habitats to be replaced should 

 be those that are most abundant, such as forest habitats, and not those in 

 short supply, such as wetlands. If possible, new developments should be 

 located where old ones have been allowed to deteriorate so no net loss of 

 habitat results. The welfare of mammals should be made an important aspect of 

 the planning stages, so that allowances can be made to leave parks and patches 

 of habitat and to provide corridors between these patches (Leedy et al. 1978). 

 In the recent past the loss of habitat to development in Wildlife Management 

 Units 7 and 8 was compensated by increases from farmland abandonment (Banasiak 



17-21 



10-80 



