Alligator mississippiensis - (Daudin, 1803)
American Alligator
Other English Common Names: American alligator
Taxonomic Status: Accepted
Related ITIS Name(s): Alligator mississippiensis (Daudin, 1801) (TSN 551771)
Unique Identifier: ELEMENT_GLOBAL.2.100172
Element Code: ARABA01010
Informal Taxonomy: Animals, Vertebrates - Crocodilians
Image 12039

Public Domain

Kingdom Phylum Class Order Family Genus
Animalia Craniata Crocodylia Alligatoria Alligatoridae Alligator
Genus Size: B - Very small genus (2-5 species)
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Concept Reference
Concept Reference: King, F. W., and R. L. Burke, editors. 1989. Crocodilian, tuatara, and turtle species of the world: a taxonomic and geographic reference. Association of Systematics Collections, Washington, D.C. 216 pp.
Concept Reference Code: B89KIN01NAUS
Name Used in Concept Reference: Alligator mississippiensis
Taxonomic Comments: Only two species in genus; the other species occurs in southeastern China (King and Burke 1989). Monotypic species. See Densmore and White (1991) for a phylogeny of the Crocodylia based on molecular data.
Conservation Status

NatureServe Status

Global Status: G5
Global Status Last Reviewed: 19Feb2014
Global Status Last Changed: 23Oct1996
Rounded Global Status: G5 - Secure
Reasons: Occurs in southeastern North America; population has shown rapid recovery with enforcement of protective legislation; populations are stable or increasing in most of range; there are currently fourteen million acres of alligator habitat; no longer biologically endangered or threatened; however, listed by USFWS as Threatened throughout entire range due to similarity of appearance to other endangered or threatened crocodilians.
Nation: United States
National Status: N5 (05Oct1996)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Alabama (S4), Arkansas (S4), Florida (S4), Georgia (S4), Louisiana (S5), Mississippi (S4), North Carolina (S3), Oklahoma (S4?), South Carolina (S5), Texas (S4)

Other Statuses

U.S. Endangered Species Act (USESA): SAT: Listed threatened because of similar appearance (new) (04Jun1987)
Comments on USESA: Listed by USFWS as Threatened rangewide due to similarity of appearance to other listed crocodilians.
U.S. Fish & Wildlife Service Lead Region: R4 - Southeast
IUCN Red List Category: LC - Least concern
Convention on International Trade in Endangered Species Protection Status (CITES): Appendix II

NatureServe Global Conservation Status Factors

Range Extent Comments: Range extends from coastal North Carolina (O'Brien and Doerr 1986) to the Florida Keys, and west to southern Texas, north to southeastern Oklahoma and Arkansas (Trauth and McCallum 2001).

Number of Occurrences: 81 to >300
Number of Occurrences Comments: Present range of EOs approximates historical range.

Population Size: 10,000 to >1,000,000 individuals
Population Size Comments: Total population is 1 million or more.

Overall Threat Impact Comments: Declined due to overharvest and habitat loss. Has increased with protection. Current primary threat is loss and degradation of habitat due to recreational use and agricultural and other development. In Louisiana, fire ants detrimentally affected nest success to a significant degree by killing hatchlings in the nest and possibly by deterring opening of nests by maternal females (Reagan et al. 2000). Resistant to human incursion as long as habitat (especially nest sites) are not disturbed.

Short-term Trend Comments: Declined greatly to a low point in the mid-1960s. Since then has increased with protection.

Other NatureServe Conservation Status Information

Inventory Needs: Continued monitoring of populations, especially size, composition, annual production, and mortality.

Protection Needs: Restrict wetland development. Enforce anti-poaching laws. Regulate harvest on sustained yield basis. Prevent/limit altered water flow to prevent flooding and inundation of nests in low lying areas.

Global Range: Range extends from coastal North Carolina (O'Brien and Doerr 1986) to the Florida Keys, and west to southern Texas, north to southeastern Oklahoma and Arkansas (Trauth and McCallum 2001).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: endemic to a single nation

U.S. & Canada State/Province Distribution
United States AL, AR, FL, GA, LA, MS, NC, OK, SC, TX

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at

Range Map Compilers: NatureServe, 2008

U.S. Distribution by County Help
State County Name (FIPS Code)
AR Hempstead (05057)
FL Alachua (12001), Baker (12003), Bay (12005), Brevard (12009), Charlotte (12015), Citrus (12017), Clay (12019), Collier (12021), Columbia (12023), Dixie (12029), Duval (12031), Escambia (12033), Flagler (12035), Franklin (12037), Gadsden (12039), Gulf (12045), Hamilton (12047), Hernando (12053), Highlands (12055), Hillsborough (12057), Holmes (12059), Indian River (12061), Jackson (12063), Jefferson (12065), Lafayette (12067), Lake (12069), Lee (12071), Leon (12073), Levy (12075), Liberty (12077), Madison (12079), Manatee (12081), Marion (12083), Martin (12085), Miami-Dade (12086), Monroe (12087), Nassau (12089), Okaloosa (12091), Okeechobee (12093), Orange (12095), Osceola (12097), Palm Beach (12099), Pasco (12101), Polk (12105), Putnam (12107), Sarasota (12115), Seminole (12117), St. Johns (12109), St. Lucie (12111), Sumter (12119), Suwannee (12121), Taylor (12123), Volusia (12127), Wakulla (12129), Walton (12131), Washington (12133)
GA Appling (13001)
MS Attala (28007)*, Bolivar (28011), Carroll (28015)*, Choctaw (28019), Claiborne (28021), Clarke (28023)*, Copiah (28029), Forrest (28035)*, George (28039), Greene (28041), Grenada (28043)*, Hancock (28045), Harrison (28047), Hinds (28049), Holmes (28051), Humphreys (28053), Issaquena (28055), Itawamba (28057), Jackson (28059), Jasper (28061), Jefferson Davis (28065)*, Jones (28067)*, Kemper (28069), Lauderdale (28075)*, Lawrence (28077)*, Leake (28079), Lee (28081), Leflore (28083), Lowndes (28087), Madison (28089), Monroe (28095), Montgomery (28097)*, Neshoba (28099), Newton (28101)*, Perry (28111), Pike (28113)*, Rankin (28121), Scott (28123)*, Sharkey (28125), Simpson (28127)*, Sunflower (28133), Tallahatchie (28135)*, Union (28145)*, Warren (28149), Webster (28155)*, Yazoo (28163)
NC Beaufort (37013)*, Bladen (37017), Brunswick (37019), Camden (37029), Carteret (37031), Columbus (37047), Craven (37049), Cumberland (37051), Currituck (37053), Dare (37055), Duplin (37061), Gates (37073), Hoke (37093), Hyde (37095), Jones (37103), Lenoir (37107)*, New Hanover (37129), Onslow (37133), Pamlico (37137), Pasquotank (37139)*, Pender (37141), Pitt (37147)*, Richmond (37153)*, Robeson (37155), Sampson (37163), Scotland (37165)*, Tyrrell (37177), Washington (37187)
OK Choctaw (40023), McCurtain (40089), Pushmataha (40127)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
03 Ghowan (03010203)+, Albemarle (03010205)+, Lower Tar (03020103)+*, Pamlico (03020104)+, Pamlico Sound (03020105)+, Middle Neuse (03020202)+*, Lower Neuse (03020204)+, White Oak River (03020301)+, New River (03020302)+, Upper Cape Fear (03030004)+, Lower Cape Fear (03030005)+, Black (03030006)+, Northeast Cape Fear (03030007)+, Lower Pee Dee (03040201)+*, Lumber (03040203)+, Little Pee Dee (03040204)+*, Waccamaw (03040206)+, Coastal Carolina (03040208)+, Altamaha (03070106)+, St. Marys (03070204)+, Nassau (03070205)+, Upper St. Johns (03080101)+, Oklawaha (03080102)+, Lower St. Johns (03080103)+, Daytona - St. Augustine (03080201)+, Cape Canaveral (03080202)+, Vero Beach (03080203)+, Kissimmee (03090101)+, Lake Okeechobee (03090201)+, Everglades (03090202)+, Florida Bay-Florida Keys (03090203)+, Big Cypress Swamp (03090204)+, Caloosahatchee (03090205)+, Florida Southeast Coast (03090206)+, Peace (03100101)+, Myakka (03100102)+, Charlotte Harbor (03100103)+, Sarasota Bay (03100201)+, Manatee (03100202)+, Hillsborough (03100205)+, Tampa Bay (03100206)+, Crystal-Pithlachascotee (03100207)+, Withlacoochee (03100208)+, Econfina-Steinhatchee (03110102)+, Aucilla (03110103)+, Upper Suwannee (03110201)+, withlacoochee (03110203)+, Lower Suwannee (03110205)+, Santa Fe (03110206)+, Apalachee Bay-St. Marks (03120001)+, Lower Ochlockonee (03120003)+, Lower Chattahoochee (03130004)+, Apalachicola (03130011)+, Chipola (03130012)+, New (03130013)+, Apalachicola Bay (03130014)+, St. Andrew-St. Joseph Bays (03140101)+, Choctawhatchee Bay (03140102)+, Pensacola Bay (03140105)+, Perdido Bay (03140107)+, Lower Choctawhatchee (03140203)+, Upper Tombigbee (03160101)+, Town (03160102)+, Buttahatchee (03160103)+, Middle Tombigbee-Lubbub (03160106)+, Noxubee (03160108)+, Sucarnoochee (03160202)+*, Chunky-Okatibbee (03170001)+*, Upper Chickasawhay (03170002)+*, Upper Leaf (03170004)+, Lower Leaf (03170005)+, Pascagoula (03170006)+, Black (03170007)+, Mississippi Coastal (03170009)+, Upper Pearl (03180001)+, Middle Pearl-Strong (03180002)+, Middle Pearl-Silver (03180003)+*
08 Lower Mississippi-Greenville (08030100)+, Little Tallahatchie (08030201)+*, Tallahatchie (08030202)+, Yalobusha (08030205)+, Upper Yazoo (08030206)+, Big Sunflower (08030207)+, Lower Yazoo (08030208)+*, Deer-Steele (08030209)+, Lower Mississippi-Natchez (08060100)+, Upper Big Black (08060201)+*, Lower Big Black (08060202)+, Bayou Pierre (08060203)+, Tangipahoa (08070205)+*
11 Pecan-Waterhole (11140106)+, Upper Little (11140107)+, Mountain Fork (11140108)+, Lower Little (11140109)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Basic Description: A large, aquatic, lizardlike reptile.
General Description: American alligators are blackish or olive drab on top. The young have bold yellowish crossbands that may persist inconspicuously into adulthood. The broadly rounded snout lacks conspicuous upward-protruding teeth. Maximum total length is about 19 feet (5.8 meters), but alligators today are generally 13 feet (4 meters) or less (Conant and Collins 1991; see also Ross and Ernst 1994). Males grow much larger than do females. In Florida during 1977-1993, the longest measured male and female alligators were 4.3 m and 3.1 m, respectively (Woodward et al. 1995, J. Herpetol. 29:507-513). Total length is about 8-9 inches (21-23 cm) at hatching. See Allsteadt and Land (1995, Herpetologica 51:314-325) for information on sexual dimorphism in the genital region of young alligators.
Diagnostic Characteristics: This species differs from the American crocodile in having a broader snout and in not having the 4th lower jaw tooth protruding conspicuously upward near the end of the snout (tooth may be inconspicuous in small crocodiles). It differs from the spectacled caiman in lacking a curved, bony, crosswise ridge in front of the eyes.
Reproduction Comments: Spring courtship involves loud bellowing and slapping of the head against the water surface. Reproductive females deposit clutches of usually about 20-60 eggs in May, June, or July (peak in late June-early July in the Everglades, north-central Florida, and Georgia). Eggs hatch in about 9 weeks. Female stays near the nest and may protect it during incubation, and she assists the emergence of the young by opening the nest mound; sometimes she carries the young in her mouth to water. Hatchlings may stay together in the vicinity of the nest and mother for 1-3 years (Behler and King 1979, USFWS 1980). Sexually mature in about 6-7 years.

In most areas, about 25-30% of the adult females nest in a particular year (Rootes and Chabreck 1993); a nesting rate of up to 68% was recorded in one area in southwestern Louisiana (see Taylor et al. 1991).

Reproductive success in the Everglades was constrained primarily by egg mortality caused by flooding (Kushlan and Jacobsen 1990). In north-central Florida, 31% of nests with complete clutches were destroyed by mammalian predators (Goodwin and Marion 1978).

Ecology Comments: During periods of drought, "gator holes" (deep areas wallowed out by alligators) are important to the survival of individuals of many aquatic animal species.

In Louisiana (Joanen and McNease 1970, 1972), nesting females had a minimum home range of 6.4-41.0 acres; males had minimum home range sizes of 452-12,560 acres and sometimes traveled over 8 km in a day.

Also in Louisiana, annual home range size of 15 radiotracked adult females was 6-166 ha; 12 of the 15 had home ranges under 50 ha (Rootes and Chabreck 1993).

See Brandt (1991) for information on the population biology of an increasing population in South Carolina.

In Georgia, nests incurred a high rate of predation by black bears (Hunt and Ogden 1991).

Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Estuarine Habitat(s): Herbaceous wetland
Riverine Habitat(s): BIG RIVER, CREEK, Low gradient, MEDIUM RIVER, Pool, SPRING/SPRING BROOK
Lacustrine Habitat(s): Shallow water
Special Habitat Factors: Burrowing in or using soil, Fallen log/debris
Habitat Comments: American alligators inhabit fresh and brackish marshes, ponds, lakes, rivers, swamps, bayous, canals, and large spring runs. They often bask on partially submerged logs or on land next to the water. Alligators dig dens in river or lake margins or in marshes; they spend cold winter and drought periods in the den They depend on access to air holes to survive in ice-covered ponds (Brandt and Mazotti 1990).

Copulation occurs in shallow water. Females deposit eggs in large mounded nests made of leaves, mud, rotting vegetation, rocks, or other debris. Nests are built in marshes or at lake or river margins. In north-central Florida, alligators nested in close proximity to permanent water, used a wide variety of available plant materials and soil in constructing nest (Goodwin and Marion 1978). Turtles (e.g., Pseudemys nelsoni) often lay eggs in alligator nests.

Adult Food Habits: Carnivore, Invertivore, Piscivore
Immature Food Habits: Carnivore, Invertivore, Piscivore
Food Comments: Opportunistic feeder. Juveniles eat mainly invertebrates: crayfish, aquatic and terrestrial insects, and mollusks; also small fishes, amphibians, and small mammals. Larger individuals eat vertebrates, including birds, reptiles (infrequently conspecifics), mammals (up to the size of deer), and fishes (USFWS 1980); also observed eating horseshoe crabs in eastern Florida. Smaller prey is swallowed whole; twists off chunks off flesh from larger prey. Digestive system commonly contains small stones.
Adult Phenology: Circadian, Hibernates/aestivates
Immature Phenology: Circadian, Hibernates/aestivates
Phenology Comments: In the northern part of the range, alligators are generally inactive or at least less active from about late November to March.
Length: 400 centimeters
Economic Attributes
Economic Comments: See Thorbjarnarson (1999) for a discussion of the limits to sustainable use of crocodilians.

See Conover and Dubow (1997) for information on alligator attacks on humans in the United States.

Management Summary
Management Requirements: Can be managed as a game species, at least in the main part of the range. See Woodward et al. (1989) for information on egg collecting for commercial use and restocking.

In the Everglades, alligator conservation depends on restoration of more predictable hydrological fluctuations than have occurred recently as a result of water management (Kushlan and Jacobsen 1990).

Monitoring Requirements: Taylor et al. (1991) used hook and line captures, aerial surveys, and examination of female reproductive anatomy to derive population estimates. See Mazzotti and Brandt (1988) for information on a live-trapping method. See Jones and Hayes-Odum (1994, Herpetol. Rev. 25:14-15) for a method for the restraint and transport of crocodilians.
Biological Research Needs: Further studies on alligator behavior and ecology.
Population/Occurrence Delineation
Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals (including eggs) in or near appropriate habitat where the species is presumed to be established and breeding.
Separation Barriers: Busy highway or highway with obstructions such that alligators rarely if ever cross successfully (does not include highways that traverse continuous aquatic/wetland habitat); untraversable topography (e.g., cliff); urbanized area dominated by buildings and pavement and lacking aquatic or wetland habitat.
Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 15 km
Separation Justification: Alligator home range sizes and movements, especially those of adult males, are extremely variable (see Migration/Mobility comments). Males may move over areas encompassing less than 100 ha or up to a little more than 5,000 ha, and males sometimes move more than 8 km in a day. Most females have annual home ranges of less than 50 ha. A 1,000-ha home range (if circular) would be roughly 3.6 km in diameter, and a 5,000-ha home range would be 8 km in diameter. The 15-km separation distance for suitable (aquatic/wetland) habitat is arbitrarily based on approximately twice the diameter of a circular 5,000-ha home range, though of course home ranges are not circular.

For the purposes of these occurrence specifications, unsuitable habitat refers to upland habitat. Movements across upland habitats would seem to be highly restricted under normal circumstances. However, a 2.2-meter female that was translocated 3.3 km returned to the original point of capture within eight days; apparently it moved overland, perhaps using a series of small wet areas as "stepping stones" (Woolard et al., 2004, Herpetol. Rev. 35:165).

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): 5 km
Date: 25Apr2005
Author: Hammerson, G.
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
NatureServe Conservation Status Factors Edition Date: 28Jan2010
NatureServe Conservation Status Factors Author: Sahley, C., and G. Hammerson.
Element Ecology & Life History Edition Date: 28Jan2010
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

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  • Brandt, L. A. 1991. Long-term changes in a population of ALLIGATOR MISSISSIPPIENSIS in South Carolina. J. Herpetology 25:419-424.

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  • Trauth, S. E., H. W. Robison, and M. V. Plummer. 2004. The amphibians and reptiles of Arkansas. University of Arkansas Press.

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Patterson, B.D., G. Ceballos, W. Sechrest, M.F. Tognelli, T. Brooks, L. Luna, P. Ortega, I. Salazar, and B.E. Young. 2003. Digital Distribution Maps of the Mammals of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Mammal Range Maps of North America:
"Data provided by NatureServe in collaboration with Bruce Patterson, Wes Sechrest, Marcelo Tognelli, Gerardo Ceballos, The Nature Conservancy-Migratory Bird Program, Conservation International-CABS, World Wildlife Fund-US, and Environment Canada-WILDSPACE."

Citation for Amphibian Range Maps of the Western Hemisphere:
IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. IUCN, Conservation International, and NatureServe, Washington, DC and Arlington, Virginia, USA.

Acknowledgement Statement for Amphibian Range Maps of the Western Hemisphere:
"Data developed as part of the Global Amphibian Assessment and provided by IUCN-World Conservation Union, Conservation International and NatureServe."

NOTE: Full metadata for the Bird Range Maps of North America is available at:

Full metadata for the Mammal Range Maps of North America is available at:

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