From the standpoint of feeding, mem- 

 bers of this guild are highly hetero- 

 geneous. Piscivorous species include the 

 cormorant, anhinga, pelicans, and mergan- 

 sers. Herbivorous species include the 

 pintail, mallard, wigeon, mottled duck, 

 and teals. A third group feeds primarily 

 on benthic mollusks and invertebrates. 

 Scaup, canvasback, redhead, and gallinules 

 belong to this group. The ducks in this 

 last group also consume a significant 

 fraction of plant material. 



Species of this guild are permanent 

 residents and usually breed in mangrove 

 swamps. As shown in Table 5, the brown 

 pelican and double-crested cormorant are 

 highly dependent upon mangroves for 

 nesting in south Florida even though both 

 will build nests in any available tree in 

 other geographical regions. It seems that 

 when mangroves are available, they are the 

 preferred nesting site. The anhinga 

 breeds in mangrove regions but is more 

 commonly found inland near freshwater (J. 

 A. Kushlan, So. Fla. Res. Ctr., Everglades 

 Natl. Park, Homestead, Fla.; personal 

 communication 1981). For the other species 

 listed in this guild, mangrove swamps 

 provide a common but not a required habi- 

 tat; all of these species utilize a 

 variety of aquatic environments. 



Kushlan et al. (in prep.) provide 

 recent data on the abundance and distribu- 

 tion of 22 species of waterfowl and the 

 American coot in south Florida estuaries. 

 The American coot is by far the most abun- 

 dant species, accounting for just over 50% 

 of the total population. Six species of 

 ducks were responsible for more than 99% 

 of the individuals seen: blue-winged teal 

 (41%), lesser scaup (24%), pintail (18%), 

 American wigeon (9%), ring-necked duck 

 (5%), and shoveler (3%). The major habi- 

 tats included in these authors' surveys 

 were coastal prairie and marshes, mangrove 

 forests, and mangrove-lined bays and 

 waterways of the Everglades National Park. 



From these data it appears that 

 waterfowl and coots are most abundant in 

 regions where mangrove, wet coastal 

 prairies, marshes, and open water are 

 interspersed. Overall, the Everglades 



estuaries support from 5% to 10% of the 

 total wi nteri ng waterfowl population in 

 Florida (Goodwin 1979; Kushlan et al. in 

 prep.). As Kushlan et al. point out, 

 however, the Everglades are not managed 

 for single species or groups of species as 

 are areas of Florida supporting larger 

 waterfowl populations. Although the 

 importance of south Florida's mangrove 

 estuaries to continental waterfowl popula- 

 tions may be small, the effect of 70,000 

 ducks and coots on these estuaries 

 probably is not (Kushlan et al. in prep.). 



Kushlan (personal communication) 

 thinks that the estuaries of the Ever- 

 glades have an important survival value 

 for some segments of the American white 

 pelican population. In winter, approxi- 

 mately 25% of the white pelicans are found 

 in Florida Bay and 75% in the Cape Sable 

 region. They feed primarily in freshwater 

 regions of coastal marshes and prairies 

 and use mangroves where they adjoin this 

 type of habitat. 



9.5 AERIALLY-SEARCHING BIRDS 



Gulls, terns, the kingfisher, the 

 black skimmer, and the fish crow comprise 

 this guild of omnivorous and piscivorous 

 species (Appendix D). These birds hunt in 

 ponds, creeks, and waterways adjacent to 

 mangrove stands. Many fishes and inverte- 

 brates upon which they feed come from 

 mangrove-based food webs. Only six of the 

 14 species are year-round residents of 

 south Florida. The least tern is an abun- 

 dant summer resident and the remainder are 

 winter residents or transients. 



Only the fish crow actually nests in 

 mangroves. Gulls and terns prefer open 

 sandy areas for nesting (Kushlan and White 

 1977b) and use mangrove ecosystems only 

 for feeding. All of the species in this 

 guild are recorded from a variety of 

 coastal and inland wetland habitats. 



9.6 BIRDS OF PREY 



This guild is composed of 20 species 

 of hawks, falcons, vultures, and owls 



67 



