(Belyea 1952). Large numbers of dead trees are conducive to fire, which often 

 follows in budworm-killed stands. Succession following fire leads to mature 

 spruce-fir stands in 50 or 60 years in which conditions are again conducive to 

 outbreaks . 



Insect defoliation may have serious ramifications for forest systems exclusive 

 of the consumption of energy. Decreased leaf surface area reduces the energy 

 available to other consumers and lowers the rates of transpiration and 

 nutrient uptake. The result is increased loss of nutrients in streamflow, 

 which increases when leaf surface area is reduced (Hibbert 1967). Other 

 destabilizing effects of insect defoliation on forest systems are: (1) 

 populations of soil invertebrates that feed on newly fallen leaves decreases; 

 (2) increased solar radiation to the forest floor increases the rate of 

 decomposition and subsequent nutrient loss (Bormann and Likens 1979). 



Insects also damage trees by boring into the bark and wood (Coleoptera, 

 Lepidoptera, and Diptera) and sucking the sap (Hemiptera). These insects 

 weaken trees and create openings where disease can enter. Other insect pests 

 in Maine's forests include the white pine weevil and balsam wooly aphid. 

 While these insects are not important as mortality factors they result in 

 reduced wood quality. 



Forest communities along the coast of Maine support abundant and diverse bird 

 populations. Warblers, vireos, thrushes, finches, flycatchers, and 

 woodpeckers are the most important groups and 100 or more species may be 

 found. A large part of the forest avifauna is migrants. Peak densities of 

 birds occur during the breeding season (May to July) , when populations of 

 breeding adults in Maine's forest average 13 to 20 birds/ha for softwood 

 stands and 15 to 16 birds/ha in hardwoods. Winter lows have not been 

 accurately determined in Maine but in New Hampshire deciduous forests, 

 populations of two to three birds/ha were recorded. Winter densities of birds 

 should be higher in softwood stands. Seed-eating finches are abundant in 

 softwood stands, which have more benign microclimate for insectivorous species 

 as well (e.g., chickadees, nuthatches, and woodpeckers). 



Most birds found in Maine forests are insectivorous during the breeding season 

 and are classified as secondary or higher level consumers. However, the 

 insects consumed by birds may be more closely tied to the detrital food chain 

 than to the grazing pathway (Bormann and Likens 1979). During most years the 

 summer diet of birds in a New Hampshire deciduous forest consists of adult 

 Diptera (whose larvae are detritivores in soil and streams), adult Coleoptera 

 (whose larvae prey on soil invertebrates), and adult Hymenoptera (secondary 

 and tertiary consumers). When an outbreak of saddled prominent caterpillars 

 occured birds switched to this source of food and became part of the grazing 

 pathway. In late summer, fall, and winter, seeds and fruits make up a large 

 portion of the diet of birds. 



Birds consume only 0.1% of the net primary production of deciduous forests in 

 New Hampshire (Holmes and Sturges 1973); however, this figure is not 

 indicative of the role of birds in forest systems. Between 1960 and 1970 the 

 yellow-bellied sapsucker was responsible for 2% and 5% of the total annual 

 mortality of softwood and hardwood trees respectively in Maine (Ferguson and 

 Kingsley 1972). This species of woodpecker drills holes in the bark of trees 

 and returns later to eat the sap and especially insects which are attracted to 



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