Field Observations Pertaining to the Systematic Status of the Great White Heron in the Florida Keys

Abstract

OF the multitude of fascinating biological problems encountered in the Florida Bay region, none seems to have excited as much interest among ornithologists as the systematic status of the Great White Heron (Ardea occidentalis) and its relationship to the Great Blue Heron (Ardea herodias). In his recent analysis of this problem, Mayr (1956) emphasized the necessity of substituting solid field work for any further speculation. During the period from December 10, 1955 to May 20, 1956, I had the opportunity of making daily observations of the herons of Florida Bay. Although my primary concern was with comparative courtship behavior, much information obtained was pertinent to the problem of the systematic status of the Great White Heron. The following is a summary of my field work relating to this problem. Area studied.-The maps (Figures 1 and 2) show the areas covered during this study. The keys visited during the period mentioned above were Bottlepoint, Cotton, Cowpens, Johnston, Key Largo, Low, Lower Matecumbe, Plantation, Stake, Upper Matecumbe, West, and Windley. Behavior.-Considerable information was accumulated on the behavior of Great White and Great Blue herons in Florida Bay, but since the problem in question is a taxonomic one, the description and analysis of behavior in these birds will be presented elsewhere. However, as far as their behavior aids in clarifying the systematic status of the birds, it can be stated here that the behavior of the blue and white birds shows no significant differences. Although he gave no details, Bond (1935) likewise found that the Great White and Great Blue herons of the West Indies behave precisely alike. Holt (1928) argued, in defense of his contention that the Great White Heron was a distinct species, that the white birds were shyer than the blue ones; this position cannot be defended on the basis of my observations. Those white and blue birds which were exposed daily to the visits of sport fishermen, bird watchers, etc. (e.g., along the intracoastal waterway), were quite tame as compared to those inhabiting the more remote keys. Some of my journal notes give the impression that in occasional situations the blue birds are shyer than the white ones. Two excerpts from my journals should suffice: