A large, colorful rail with dark purple to blue colors and a large red bill and frontal shield, the Gray-headed Swamphen is a recent addition to the avifauna of North America due to the establishment of a nonnative population in southeastern Florida. Although recently known as the Purple Swamphen (Porphyrio porphyrio), the taxonomy of this species is complex and various taxonomic bodies now spilt the P. porphyrio complex into 6 species, including the Gray-headed Swamphen (P. poliocephalus). For further information on the taxonomy of Porphyrio, see Systematics.

The native range of the Gray-headed Swamphen extends from the Middle East through India and southern Asia to northern Thailand. In 1996, this swamphen was discovered in Florida at Pembroke Pines in Broward County, the result of unintended releases from one or two private collections nearby. The following decade saw the Gray-headed Swamphen expand its range within Southeast Florida, including the Everglades, the Everglades Agricultural Area, and Lake Okeechobee, with dispersers found outside this region. From October 2006 through December 2008, an eradication program by state agencies removed 3,187 swamphens ( Hardin, S., E. Donlan, M. Ward and D. Eggeman. 2011. Attempted eradication of Porphyrio porphyrio Linnaeus in the Florida Everglades. Management of Biological Invasions no. 2 (1):47-55. Close Hardin et al. 2011). However, the eradication campaign was deemed a failure at reducing the distribution and abundance of swamphens, and was discontinued. Since then, the Gray-headed Swamphen has continued to increase in the region and the species is now a common sight in stormwater treatment areas, water conservation areas, agricultural areas, and constructed wetlands in urban and suburban Southeast Florida. However, range expansion to date has mostly been limited to Southeast Florida.

The Gray-headed Swamphen has received little study in Florida (e.g., Pranty, B., K. Schnitzius and H. W. Lovell. 2000. Discovery, origin, and current distribution of the Purple Swamphen (Porphyrio porphyrio) in Florida. Fla. Field Nat. no. 28:1-11. Close Pranty et al. 2000, Hardin, S., E. Donlan, M. Ward and D. Eggeman. 2011. Attempted eradication of Porphyrio porphyrio Linnaeus in the Florida Everglades. Management of Biological Invasions no. 2 (1):47-55. Close Hardin et al. 2011, Pranty, B. 2012. Population growth, spread, and persistence of Purple Swamphens (Porphyrio porphyrio) in Florida. Florida Field Naturalist no. 40 (1):1-12. Close Pranty 2012, Pranty, B. 2013a. Introducing the Purple Swamphen: Management, taxonomy, and natural history. Birding no. 45 (3):38-45. Close Pranty 2013a, Callaghan, C. T. and D. E. Gawlik. 2016. Diet and selectivity of the Porphyrio porphyrio (Purple Swamphen) in Florida. Southeastern Naturalist. Close Callaghan and Gawlik 2016). As a result, we incorporate into this account information on the Gray-headed and other closely related swamphens (Porphyrio) from the Old World (e.g., see Ripley, S. D. 1977. Rails of the world: A monograph of the family Rallidae. Boston, MA: David R. Godine. Close Ripley 1977, Taylor, P. B. 1996. "Family Rallidae (rails, gallinules, and coots)." In Handbook of the birds of the world. Vol. 3: Hoatzins to auks., edited by J. del Hoyo, A. Elliott and J. Sargatal, 108-209. Barcelona: Lynx Edicions. Close Taylor 1996, Taylor, B. 1998. Rails: A guide to the rails, crakes, gallinules and coots of the world. New Haven: Yale University Press. Close Taylor 1998). More detailed information was compiled for various sections of this account; e.g., habitat ( Taylor, P. B. 1996. "Family Rallidae (rails, gallinules, and coots)." In Handbook of the birds of the world. Vol. 3: Hoatzins to auks., edited by J. del Hoyo, A. Elliott and J. Sargatal, 108-209. Barcelona: Lynx Edicions. Close Taylor 1996, Freifeld, H. B., D. W. Steadman and J. K. Sailer. 2001. Landbirds on offshore islands in Samoa. Journal of Field Ornithology no. 72 (1):72-85. Close Freifeld et al. 2001), breeding ( Craig, J. L. 1980a. Breeding success of a communal gallinule. Behavioral Ecology and Sociobiology no. 6 (4):289-295. Close Craig 1980a, Craig, J. L. 1980b. Pair and group breeding behaviour of a communal gallinule, the Pukeko, Porphyrio porphyrio. Animal Behaviour no. 28 (MAY):593-603. Close Craig 1980b, Jamieson, I. G. and J. L. Craig. 1987a. Dominance and mating in a communal polygynandrous bird: Cooperation or indifference towards mating competitors? Ethology no. 75 (4):317-327. Close Jamieson and Craig 1987a, Jamieson, I. G. and J. L. Craig. 1987b. Male-male and female-female courtship and copulation behaviour in a communally breeding bird. Animal Behaviour no. 35 (4):1251-1253. Close Jamieson and Craig 1987b, Jamieson, I. G. 1997. Testing reproductive skew models in a communally breeding bird, the Pukeko, Porphyrio porphyrio. Proceedings of the Royal Society B-Biological Sciences no. 264 (1380):335-340. Close Jamieson 1997, Craig, J. L. and I. G. Jamieson. 1988. Incestuous mating in a communal bird: A family affair. American Naturalist no. 131 (1):58-70. Close Craig and Jamieson 1988), behavior ( Holyoak, D. T. 1970. The behaviour of captive Purple Gallinules (Porphyrio porphyrio). Avicultural Magazine no. 76:98-109. Close Holyoak 1970, Craig, J. L. 1977. The behaviour of the Pukeko, Porphyrio porphyrio melanotus. New Zealand Journal of Zoology no. 4 (4):413-433. Close Craig 1977), evolution ( Garcia-R., J. C. and S. A. Trewick. 2015. Dispersal and speciation in Purple Swamphens (Rallidae: Porphyrio). Auk no. 132 (1):140-155. Close Garcia-R. and Trewick 2015), and diet ( Carroll, A. L. K. 1966. Food habits of Pukeko (Porphyrio melanotus Temminck). Notornis no. 13 (3):133-144. Close Carroll 1966, Norman, F. I. and L. Mumford. 1985. Studies on the Purple Swamphen, Porphyrio porphyrio, in Victoria. Australian Wildlife Research no. 12 (2):263-278. Close Norman and Mumford 1985).

Although the Gray-headed Swamphen is predominantly sedentary within its native range, Porphyrio are known to disperse long distances (> 300 km) in response to unsuitable water levels (e.g., Vielliard, J. 1973. The Purple Gallinule in the marismas of the Guadalquivir. British Birds no. 67 (6):230-236. Close Vielliard 1973, Sánchez-Lafuente, A. M., F. Valera, A. Godino and F. Muela. 2001. Natural and human-mediated factors in the recovery and subsequent expansion of the Purple Swamphen Porphyrio porphyrio L. (Rallidae) in the Iberian Peninsula. Biodiversity and Conservation no. 10 (6):851-867. Close Sánchez-Lafuente et al. 2001), and such dispersal has been documented in Florida ( Pranty, B. 2012. Population growth, spread, and persistence of Purple Swamphens (Porphyrio porphyrio) in Florida. Florida Field Naturalist no. 40 (1):1-12. Close Pranty 2012). Their excellent dispersal ability combined with the abundance of an important food plant in Florida, the Gulf Coast spikerush (Eleocharis cellulosa; Pranty, B. 2013a. Introducing the Purple Swamphen: Management, taxonomy, and natural history. Birding no. 45 (3):38-45. Close Pranty 2013a, Callaghan, C. T. and D. E. Gawlik. 2016. Diet and selectivity of the Porphyrio porphyrio (Purple Swamphen) in Florida. Southeastern Naturalist. Close Callaghan and Gawlik 2016), has raised concern among wildlife managers about further expansion of the species. As a result, additional research on the potential impacts to native flora and fauna is badly needed.