Although exotics can become nuisances at any time, the red-whiskered bulbul has not yet become a threat. Robertson and Woolfenden (1992) reported that red-whiskered bulbul populations have spread minimally and are barely surviving. Stoll (1977) believed that the red-whiskered bulbul may be in competition with the mockingbird (Mimus polyglottos) because the food habits of the two species are similar. If its populations grow substantially, the red-whiskered bulbul may pose future problems to fruit growers. The only real danger that now exists is the bulbul's diet of Brazilian pepper drupes. The bird may become a major pathway by spreading the seed of the Brazilian pepper in Florida. As the birds fly to new areas, viable seeds from droppings germinate. The red-whiskered bulbul may also intensify the spread of this noxious exotic (Stoll 1977).
Cattle Egret (Bubulcus ibis). Although the cattle egret is not typically classified as an aquatic species, it is a nonindigenous species with high visibility. This species belongs to a taxon that is known to peregrinate or migrate (Owre 1973). Because this species may have migrated to the New World and to Florida on its own, it may not be an exotic species. The cattle egret's pathway of introduction is unknown. However, its sudden appearance, increase in numbers, and range expansion soon after it was first observed are similar to those of other exotic species. W.E. Dilley first discovered the cattle egret in the United States near Clewiston, Hendry County, in summer 1941, and on 5 May 1953, G. Chandler and S.A. Grimes found nesting individuals of this species at King's Bar, Lake Okeechobee (Sprunt 1955). In summer, cattle egrets are now common throughout Florida except in the Keys; during winter, the abundance of these birds considerably declines (Robertson and Wolfenden 1992). Unlike most exotic birds, the cattle egret invaded Florida on its own (Owre 1973).
The cattle egret established itself because it can easily adapt its diet to the habitat. This species is most noted for its adaptability and non-competitiveness (Sprunt 1954). Cattle egrets are most typical on pastures where they follow cattle or plows and prey on flushed insects, including insects that are considered pest species and fill empty niches. Although the cattle egret nests in the same colonies and forages on the same grounds as the native herons (Family Ardeidae), its variable diet precludes serious competition with other heron species (Fogarty and Hetrick 1973). Because of its status as an adaptive, non-competitive species, the cattle egret was deliberately introduced to the Seychelles and to the Hawaiian Islands to control flies (Long 1989). However, the cattle egret preys on the eggs of ground-nesting birds in Africa and America (Cunningham 1965). Although the bird is considered a pest by many environmentalists, it consumes many insects and to our knowledge has not created major environmental problems.
Budgerigar (Melopsittacus undulatus). The budgerigar, commonly known as the budgie, is indigenous to interior Australia. Budgerigars are popular pets throughout the world but are established only in Florida (Forshaw 1973). This species nested in Pinellas County as early as in the 1950's (Robertson and Woolfenden 1992). It nests at Horseshoe Beach, Dixie County; in Hudson, Pasco County, south to Fort Myers, Lee County (Wenner and Hirth 1984); and in Naples, Collier County. Budgerigar may once have been established around Jacksonville, Duval County, but no further sightings have been made in this area (Robertson and Woolfenden 1992). At one time, a population of budgerigars in St. Petersburg was so large, it was a tourist attraction (Owre 1973). Many sightings were reported elsewhere in the peninsula, in the Keys, and in the panhandle of Florida (Robertson and Woolfenden 1992). Populations of budgerigars peaked at many thousands in the later 1970's and declined in the 1980's (Robertson and Woolfenden 1992). Although the population sizes and the number of locations declined, budgerigars may still be seen throughout southern Florida. They inhabit watercourses, sparsely timbered grasslands, dry scrublands, open plains, and residential areas of southern Florida, and Immelman (1968) believed that they are the most prolific Australian parrot of the United States.
