Figure 10. Clapper rail ( Ral lus 

 longirostris ) standing on the high marsh 

 area at Great Sippewissett Salt Marsh, 

 Massachusetts. Clapper rails feed on 

 animals of the intertidal salt marsh and 

 may also nest in its upper edges. Photo 

 by J.M. Teal, Woods Hole Oceanographic 

 Institution. 



make seasonal use of it is much larger. 

 Dabbling ducks of various kinds sieve 

 seeds and small animals from the 

 sediments. In winter, black ducks ( Anas 

 rubripes ) feed extensively on the salt 

 marsh, especially at high tide when they 

 pluck the snail Melampus from the grass. 

 Snow geese ( Chen caerulescens ) eat roots 

 and rhizomes of the grass (Figure 11); 

 Canada geese ( Branta canadensis ) graze on 

 Spartina (Figure 12). Many kinds of 

 shorebirds probe for invertebrates (insect 

 larvae, mollusks, Crustacea, and worms) in 

 the more open areas. Herons, egrets, 

 bitterns, and ibis stalk fishes and 

 crustaceans along the creeks and in the 

 ponds while ospreys, kingfishers, and 



various terns dive from the air above. 

 Though most of the feeding activity is in 

 the creeks adjacent to the grassy parts of 

 the marsh, it is nevertheless connected to 

 the functioning of the marsh. 



Exceptionally high tides in autumn 

 occasionally force insects to the tops of 

 the Spartina , and many kinds of birds, 

 from sparrows and warblers to terns and 

 gulls, come to feed on this bonanza of 

 exposed insects. Swallows capture flying 

 insects in the air above the marsh much as 

 they do over upland meadows. Birds are 

 like insects, adapted to marsh living by 

 their water-saving uric acid excretion and 

 by orbital glands which secrete excess 

 salt from their blood. 



Mammals constitute a smaller and 

 generally less conspicuous part of the 

 marsh fauna. The most abundant marsh 

 mammal in New England is the meadow mouse 

 or vole, Microtus pennsyl vanicus . In the 

 high marsh, where meadow mouse runs are 

 obvious beneath the grass, the mouse is a 

 more conspicuous resident. Although the 

 meadow mouse's feeding is restricted to 

 low tide in the low marsh, the large 

 fraction of plants damaged by the mice 

 indicates that the Microtus is a signifi- 

 cant part of the marsh system. The damage 

 to the sward by the meadow mouse is far 

 greater than the actual consumption of 

 Spartina . Microtus cuts off the base of a 

 plant and eats a small portion of the 

 tender basal part; the rest of the stem is 

 left to wither and die. Under natural 

 conditions on Great Sippewissett Salt 

 Marsh, about 7% of the short S. alterni - 

 f lora plants show signs of insect damage 

 whereas about 2.5% show damage by mice. 

 In the fertilized plots where Spartina 

 productivity is enhanced, the insect 

 damage drops to about 5%, but 20%-30% of 

 the plants are damaged by mice (Vince 

 1979; Valiela and Teal, unpubl. data). 

 Thus, under these conditions, Microtus can 

 have a significant effect on Spartina 

 production. 



White-footed mice ( Peromyscus 

 leucopus ), which are primarily seed 

 eaters, occasionally come down into the 

 low marsh. In the marshes of the southern 

 United States, the rice rat, Oryzomys 

 palustris , is a permanent resident in tall 

 Spartina areas. Small mammals such as 



19 



