For the purposes of this investigation, the terrestrial communities of 

 the Aransas uplands are catagorized as maritime woodland, coastal grasslands, 

 and brush-grass ecotone. The ecotonal community represents the major 

 successional stage in the natural transition from coastal grasslands (bluestem 

 grasslands) to maritime woodland (live oak forest). The transition rate and 

 direction are effectively regulated by several important environmental factors. 

 These factors were described in the ecological analysis of the coastal uplands. 



Wildlife . Because the local abundance and diversity of wildlife popula- 

 tions are directly tied to the heterogeneity of the existing plant communities, 

 the Aransas Refuge, with its diverse habitat variation, supports and outstanding 

 wildlife population. Three endangered species are included among the more than 

 300 species of birds and 35 species of mammals that utilize the refuge. The 

 most widely publicized member of this category is the whooping crane. The 

 refuge, adjacent bays, and nearby islands comprise the principal wintering 

 ground for the world's last ancestral flock of whooping cranes. North America's 

 largest and rarest migratory bird. The birds occupy the refuge from mid-October 

 to mid-April. Other resident endangered species include the eastern brown 

 pelican ( Pelecanus occidental's carolinensis ), and Attwater's prairie chicken. 

 Occasionally, the peregrine falcon ( Falco peregrinus ) may inhabit the refuge 

 during migration. Over 55 species of reptiles and amphibians are found on the 

 refuge. 



Waterfowl are an important and conspicuous component of the wildlife popu- 

 lation, particularly during the fall and winter months when local marshes, ponds, 

 swales, and grain fields attract large wintering flocks. In 1976, a total of 

 3,478,530 waterfowl use-days were recorded for 21 species (USDI, 1976a^). The 

 most abundant species were the Canada goose ( Branta canadensis ), snow goose 

 ( Chen hyperborea ), shoveler ( Spatula clypeata ), American wigeon ( Anas strepera ), 

 green-winged teal ( Anas crecca ), and American coot ( Fulica americana ). 



Upland species of particular interest associated with the maritime wood- 

 lands and brush-grass complex are the white-tailed deer, javelina, feral swine, 

 raccoon, bobcat, coyote, fox squirrel, armadillo, turkey, and bobwhite. Rarely 

 observed mammalian species include the ringtail ( Bassariscus astutus ), coati 

 ( Nasua narica ), badger ( Taxidea taxus ), mountain lion ( FeTTs concolor ), swamp 

 rabbit, rice rat ( Oryzomys palustris ), and pygmy mouse ( Baiomys taylori ). 



The gradual expansion of the woody components (woodlands/brush-grass 

 complex) into the grasslands has been insidious, and has had both good and bad 

 effects upon certain wildlife species. Those species linked to the woodlands 

 and ecotonal areas for food and cover benefit from habitat expansion; those 

 associated with the dwindling grassland resources have experienced steady popu- 

 lation declines. (Blakey, 1947). Attwater's prairie chicken, a grassland 

 associate, has been especially affected as broad grassy expanses have disappeared 

 (Lehmann, 1941), while the white-tailed deer and Rio Grande turkey, ecotonal 

 and woodland species, maintain very high population levels on the refuge (Blakey, 

 1947; White, 1973). 



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