Four of the species listed in 

 Table 32 are considered endangered 

 in Florida, the green turtle ( Chelo- 

 nia mydas ), the Atlantic hawksbill 

 ( Eretomochelys imbricata imbricata ) , 

 the Atlantic ridley ( Lepidochelys 

 kernpii ) , and the American crocodile 

 ( Crocodylus acutus ) (McDiarmid 

 1978). The Atlantic loggerhead 



( Caretta caretta caretta ) and the 

 mangrove (ornate water) terrapin 

 ( Malaclemys terrapin rhizophorarum ) 

 are considered threatened. The 



American alligator ( Alligator mis- 

 sissippiensis ) and eastern indigo 

 snake ( Drymarchon corais couperi ) 

 are considered species of special 

 concern. 



7.35 BIRDS 



Odum et al. (1982) list 181 

 species of birds utilizing the man- 

 grove zone throughout south Florida. 

 These authors divide the avifauna 

 into six convenient categories based 

 on feeding habits. These categories 

 are wading birds, probing shore- 

 birds, floating and diving water 

 birds, aerially searching birds, 

 birds of prey, and arboreal birds. 



Of all categories, the wading 

 birds, the aerially searching birds 

 (terns, gulls, black skimmer, fish 

 crow), and floating and diving water 

 birds are the most conspicuous. The 

 most abundant wading bird in the 

 mangrove zone of the lower Ever- 

 glades is the Louisiana heron (Kush- 

 lan and White 1977, Kushlan 1979). 

 The double crested cormorant, an 

 almost exclusive estuarine resident, 

 and the snowy egret are next in 

 numerical importance. The white 

 ibis and the wood stork utilize the 

 mangrove zone less frequently (for 

 nesting at least) than the above 

 species. 



Studies conducted on these lat- 

 ter two species offer insight into 

 regional patterns of resource parti- 



tioning between two of many species 

 that seemingly compete for a common 

 resource. Nesting success in the 

 wood stork has been shown to be 

 heavily dependent on the timing and 

 rate of seasonally declining water 

 levels, whereas the white ibis is 

 capable of exploiting both rising 

 and declining water level situations 

 (Kushlan 1979). The white ibis is 

 relatively more nomadic than the 

 wood stork, being inclined to move 

 more often in search of suitable 

 foraging grounds and at different 

 times of the year. Both white ibis 

 and wood storks use the mangrove 

 zone extensively for foraging, espe- 

 cially during their nesting seasons. 

 The two differ, however, in the time 

 of mating, in feeding strategies, 

 and in prey selectivity. The wood 

 stork nests from December through 

 March while white ibis nesting is 

 highly variable between March and 

 December (Kushlan 1979, Odum et al. 

 1982). The wood stork is a tactile 

 feeder relying heavily on touch as 

 it gropes, rather nonselectively, 

 through heavy vegetation for its 

 prey (Kahl 1964). The white ibis is 

 also primarily a tactile prober but 

 does occasionally use sight, espe- 

 cially on land. While wood storks 

 tend to nest and feed when and where 

 prey concentrations peak, white ibis 

 substitute a more general use of a 

 number of high energy habitats. The 

 relative size of the ibis and the 

 presence of other species willing 

 and capable of robbing larger prey 

 generally limit the size of prey 

 consumed. Herons, egrets, and 



grackles often steal larger prey 

 from white ibis. Consequently, 



white ibis generally subsist on 

 small prey which can be swallowed 

 quickly. In the mangrove zone dur- 

 ing nesting, ibis tend to selective- 

 ly take small frogs, anoles, cray- 

 fish, and water bugs in addition to 

 small fish; they generally move to 

 the coastal swamps during the sum- 

 mer. In general terms of resource 



161 



