occur during the breeding season (May to July) . Most palustrine wetland- 

 inhabiting birds are insectivorous during the breeding season even if they are 

 otherwise mostly herbivorous. Waterfowl, for example, feed on invertebrates 

 during the breeding season but in late summer and fall revert to seeds and 

 fruit for the greater portion of their diet. 



Waterfowl production on small palustrine wetlands in Maine was evaluated by 

 Spencer (1963). He found that among small wetlands producing ducks those in 

 the coastal zone and those in the 5 to 10 acre (2 to 4 ha) size range produced 

 more young birds than inland and larger wetlands. Forested wetlands are espe- 

 cially important for hole-nesting species of waterfowl, including wood ducks 

 and mergansers. Bog wetlands support a unique community of passerine birds 

 including palm warblers, Wilson's warblers, and Lincoln sparrows. Uncommon 

 species of birds in Maine found exclusively breeding in a variety of palus- 

 trine habitats include short-billed marsh wren (sedge-dominated emergent 

 wetland), least bittern (emergent wetland), willow flycatcher (willow domi- 

 nated scrub/shrub wetland), and marsh hawk (emergent wetland). During the mi- 

 gration period palustrine wetland inhabiting-species from other areas concen- 

 trate in Maine wetlands for feeding and resting. 



Decomposers 



Organic matter produced in palustrine areas is: (1) degraded into its recy- 

 clable constituents, such as nitrogen and phosphate, by bacteria and fungi; 

 (2) stored as peat; or (3) exported from the system by water flow. The rela- 

 tionship between the rate of organic matter accrued and the rate of decomposi- 

 tion determines the rate of peat formation (see below) . No data exist on 

 decomposer species composition and rates of decomposition in wetland systems 

 in coastal Maine. 



Food Webs 



A generalized food web for the community of a Maine palustrine wetland is 

 given in figure 8-8. The generic examples listed are known to occur commonly 

 in palustrine wetlands in coastal Maine. The base of the web consists of the 

 lower plants and vascular plants. These are fed upon by fish, mammals, 

 invertebrates, and zooplankton. These, in turn, are fed upon by fish, birds, 

 mammals, invertebrates, reptiles, and amphibians. Many organisms occupy more 

 than one trophic level. The heterotrophic bacteria and fungi ingest feces, 

 dead organisms, and dissolved organic matter from various sources. These may, 

 in turn, be ingested by consumers. However, much of the organic matter is 

 stored as peat due to the slow rate of decomposition in Maine wetlands. 



Feeding relationships based on specific paths of energy through organisms have 

 not been studied in Maine palustrine wetlands. 



ENERGY FLOW 



In most biological systems the reduced compounds and organic material entering 

 the food chain are broken down, stored, and respired by organisms. Eventually 

 these organisms decompose. Much of the energy is dissipated in each of these 

 steps. In the palustrine system of coastal Maine, however, the activity of 

 decomposer organisms may be too slow to effect complete decomposition because 

 of low temperature, low pH, and waterlogging. Fungal decomposers are not well 



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