The Mangrove Cuckoo is among the most poorly known North American birds. Skulking and secretive by nature, it is usually difficult to observe. As a result, most aspects of this species' reproductive biology, ecological requirements, and population dynamics remain a mystery. Surprisingly, this species can be quite tame and inquisitive when encountered.
The Mangrove Cuckoo inhabits coastal regions of southern Florida, south through the Caribbean islands, and on both coasts of Mexico and Central America. It may also occur sporadically in lowland areas of South America from Venezuela east to the mouth of the Amazon River. The common name Mangrove Cuckoo is somewhat of a misnomer. The species is not restricted to mangroves, but is widely distributed in many lowland habitats, occupying scrub or woodlands, including humid forest, from sea level to about 1,400 m. It may be found in a broader range of habitat types on Caribbean islands than in most mainland areas. In addition, the Mangrove Cuckoo has been observed infrequently more than 100 km from the coast.
Taxonomists have divided the species into as many as 14 subspecies ( Peters 1940b ) on the basis of differences in wing length and plumage coloration, often using very limited samples. Recent study, however, suggests that these observed differences may be due to individual variation rather than to geographic variation. Some publications (e.g., Banks and Hole 1991 , Smith 1996j ) now treat the species as monotypic; although detectable differences in size and plumage coloration may yet prove to be significant.
The seasonal movements of the Mangrove Cuckoo are equally perplexing. Once thought to be fully migratory in Florida, winter sightings are becoming increasingly frequent in all parts of its Florida range. The tendency of this species to remain silent when not breeding renders it almost undetectable to casual observers during fall and winter months. Further study of Mangrove Cuckoos wintering in Florida may indicate that the species is not migratory, and hence the few purported migrants collected on wintering grounds in South America may be pale variants of resident populations.
The range of the Mangrove Cuckoo in Florida is restricted to southern and central coastal areas that are popular for residential and recreational purposes. Because the species is highly sensitive to habitat fragmentation that characterizes this type of development, it may already be extirpated from many unprotected areas. Fortunately, large tracts of mangrove are located in state and national parks within its range. Continued acquisition of lands for protection is essential to ensure that the Mangrove Cuckoo maintains a continuous breeding distribution in Florida.