According to Ogden (1978), nest 

 preparation begins during April with 

 females digging or redigging sand or 

 soil nest mounds approximately 6.1 m 

 (20 ft) in diameter and 0.6 m (2 ft) 

 high. The same nest mound may be 

 used in consecutive years and one or 

 more alternate mounds may also be 

 maintained. About half of the nests 

 fail to hatch by late July or early 

 August, presumably due to egg preda- 

 tion or low temperature stress. 



Some controversy exists over 

 whether juvenile American croco- 

 diles, like their close relatives, 

 require fresh or brackish water 

 conditions for optimum growth and 

 survival (National Fish & Wildlife 

 Laboratory 1980). Recently Dunson 

 (1980) has shown that young 

 crocs lose about 1.7% body weight 

 per day when placed in full sea 

 water. He observes that this 



loss may be compensated for by 

 two mechanisms: 



(1) young crocs spend a great 

 deal of their time in moist, 

 cool terrestrial environ- 

 ments such as crab holes, 

 wave cut crevices, and man- 

 grove roots; body weight 

 loss is less under these 

 conditions; and 



(2) feeding on fish and inverte- 

 brates which are high in 

 water and low in sodium. 



Rates of weight loss under these 

 same conditions decrease rapidly 

 with size of the animal. 



Adult crocodiles feed primarily 

 on fish (mullet). Population esti- 

 mates are placed at between 200 to 

 400 individals, of which only about 

 25 are breeding females (Ogden 

 1978). Dunson (1980) speculates 

 that upland drainage alterations to 

 Florida Bay may be responsible for 

 the lack of a crocodile comeback, as 

 well as its tendency to move into 

 upper and northern reaches of Flori- 



da Bay. This strongly implies a 

 degree of dependence on oscillating 

 salinity conditions. 



Another endangered reptile that 

 frequents Florida Bay is the Atlan- 

 tic hawksbill turtle ( Eretmochelys 

 imbricata imbricata ). Although it 

 is more widespread than the croco- 

 dile in south Florida, the hawksbill 

 is also a primarily tropical spe- 

 cies. Florida populations exist at 

 the northern edge of the species 

 range. Nesting in south Florida 

 waters is at best occasional. The 

 hawksbill is generally associated 

 with reef communities, but its omni- 

 vorous habits often lead it into 

 seagrasses and other habitats. 



The endangered Atlantic ridley 

 turtle ( Lepidochelys kempii ) is 

 limited in its range to the Gulf of 

 Mexico and occasionally occurs in 

 Florida Bay. Although it now only 

 rarely breeds in southwest Florida, 

 the endangered Atlantic green turtle 

 ( Chelonia mydas mydas ) was once an 

 important herbivore of south Florida 

 seagrasses (Zieman 1982). 



8.35 BIRDS 



In general, Florida Bay affords 

 significant habitat for wading and 

 probing shorebirds, oceanic birds, 

 and floating and diving birds. Re- 

 latively less habitat is available 

 for arboreal and other land birds. 



The importance of Florida Bay 

 in wading bird production is exem- 

 plified by the fact that of the 41 

 nesting sites recorded in south 

 Florida in 1974-1975, 14, or 34% 

 were located in the bay (Kushland 

 and White 1977). All but 3 of 500 

 roseate spoonbill ( Ajaia ajaja ) 

 nests were located in the bay. 

 Likewise, breeding of the reddish 

 egret, double crested cormorant, and 

 black crowned night heron are fairly 



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