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Record Total Lengths of the American Alligator in Florida
Arnold M. Brunell, J. Patrick Delaney, Richard G. Spratt, Dwayne A. Carbonneau, and Jason E. Waller

Southeastern Naturalist, Volume 12, Issue 4 (2013): N9–N17

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Record Total Lengths of the American Alligator in Florida Arnold M. Brunell1,*, J. Patrick Delaney1, Richard G. Spratt2, Dwayne A. Carbonneau3, and Jason E. Waller3 Abstract - Claims of unusually large crocodilians are often questionable because of the lack of physical evidence and a verification process. We report on the longest Alligator mississippiensis (American Alligator) that has been officially measured in Florida. The state record for the longest alligator is 435.5 cm (14 ft 3.5 in) and is only the third specimen in Florida known to exceed 426.5 cm (14 ft). Discussion is presented about the measurements taken, techniques used to obtain the measurements, and personnel required for officially recognizing record specimens. We emphasize the importance of having qualified biologists verify measurements using standardized techniques and recommend that other states within the alligator’s range develop a protocol similar to Florida’s for measuring exceptionally large alligators. The general public typically is keenly interested in knowing about the largest attainable size of wildlife species such as Alligator mississippiensis Daudin (American Alligator). Yet questionable records of large specimens are commonly presented as fact and provided for public reference. For instance, Conant and Collins (1998) report that the record total length (TL) for an American Alligator is 584 cm (19 ft 2 in), as reported by McIlhenny (1935). However, Woodward et al. (1995) noted that this report lacked any tangible evidence (e.g., skull) or corroborating documentation to support the claim. Woodward et al. (1995) also presented an argument, based on estimated TLs from the largest known existing skulls, that an alligator of that length was highly unlikely. For these reasons, the Florida Fish and Wildlife Conservation Commission (FWC) recognizes lengths of exceptionally large alligators only in the cases where an FWC biologist has collected and recorded size data in accordance with standardized techniques. Alligators mostly inhabit freshwater systems and occur in warm temperate regions, unlike most other crocodilians, which occur in subtropical or tropical regions (Mazzotti and Brandt 1994). Alligators are found throughout Florida, as well as several other states in the southeastern United States. Although alligators were once classified as federally endangered, their populations have rebounded such that they are now legally hunted in many states (David et al. 1996, Dutton et al. 2002, Rhodes 2002). Alligators have been legally harvested within Florida since 1977, and annual harvests average approximately 15,000–20,000 /yr. Of these, approximately 7000 are from the statewide harvest on public waterways, 9000 are harvested as nuisance alligators (i.e., alligators perceived as being a threat to people, pets, or livestock on private or public waterways), and another 4000 alligators from managed harvests on privately-owned wetlands (Florida Fish and Wildlife Conservation Commission 2011). When the FWC receives a report of an exceptionally large alligator, it assigns biologists the task of measuring it. Relying on trained biologists ensures that the measurements are performed in a standardized way, and such consistency is the standard for measuring trophy game. For example, all of the records recognized by the Boone and Crockett Club must be validated by one of its Official Measurers (Buckner and Reneau 2009). Boone and Crockett Official Measurers must have successfully completed the 1Florida Fish and Wildlife Conservation Commission, 601 W. Woodward Avenue, Eustis, FL 32726. 2Florida Fish and Wildlife Conservation Commission, 8864 C.R. 247, Lake Panasoffkee, FL 33538. 3Florida Fish and Wildlife Conservation Commission, 1239 S.W. 10th Street, Ocala, FL 34471. *Corresponding author - Arnold.Brunell@myFWC.com. Notes of the Southeastern Naturalist, Issue 12/4, 2013 N9 2013 Southeastern Naturalist Notes Vol. 12, No. 4 N10 A.M. Brunell, J.P. Delaney, R.G. Spratt, D.A. Carbonneau, and J.E. Waller club’s training workshop for scoring all of the trophy categories recognized by the club. Furthermore, Boone and Crockett world records must be validated by panel judges who have been selected by the Records Committee, which oversees the record-keeping efforts for the club. The FWC administers the Florida Buck Registry, a program for Florida hunters that is similar to Boone and Crockett’s program for scoring and validating trophy deer (D. Francis and A. Kane, FWC, Quincy and Panaman City, FL, pers. comm.). Both programs maintain the integrity of their records by accepting only standardized measurements taken by officially trained measurers. To ensure standardization, the FWC developed a protocol for measuring alligators that follows the generally accepted convention in North America for measuring reptiles and amphibians from Conant and Collins (1998), which uses a straight-line distance for length and considers the cloaca (i.e., vent) to be part of the trunk instead of the tail. Straight-line measurements are taken with a steel measuring tape, and girth measurements are taken with a nylon measuring tape. English units are commonly used for reporting sizes of alligators in the United States, and English and metric measuring tapes are sometimes used interchangeably. When converting from English to metric, we round to the nearest 0.5 cm. This protocol was initially used in Florida for research conducted between 1981 and 1990 to collect morphometric data from more than 3000 alligators harvested during experimental alligator harvests (Woodward et al. 1992), and has continued to serve as FWC’s standardized guidelines for measuring alligators. Measurements included in the FWC protocol for record alligators are TL, snout–vent length (SVL), head length (HL), tail girth (TG), and weight (WT). Total length is the straight-line measurement from the tip of the snout to the tip of the tail (Fig. 1). This is best accomplished by placing marks on a flat, level surface at the two extremes and measuring the distance between them after the alligator has been removed. Tail injuries that affect TL should be noted with an estimation of the amount missing. It might be difficult or impossible in these cases to know what the TL would have been without the injury, but this information can be of interest for future reference. Although over-the-back (dorsal) measurements of TL are commonly used when working with live alligators in confined spaces, such as on a small boat, we use the straight-line method for record alligators due to concerns that greater length and greater variation could result from following the contours of the alligator ’s body (Britton et al. 2012). Snout–vent length is the straight-line distance from the tip of the snout to the posterior margin of the cloaca (Fig. 2). This measurement can be taken using a metal tape with the animal lying on its back on a flat surface. The metal tape can help ensure that a straight-line measurement is obtained. Snout–vent length can also be measured in a fashion similar to TL while the animal is lying on its belly on a flat, level surface. Unlike measuring TL, however, the tail must be lifted enough to mark the posterior margin of the cloaca on the flat surface. In crocodilians, SVL is highly correlated with TL and therefore can serve as an indicator of Figure 1. The standard total length (TL) measurement of an American Alligator is the straight-line distance from the tip of the snout to the tip of the tail. N11 2013 Southeastern Naturalist Notes Vol. 12, No. 4 A.M. Brunell, J.P. Delaney, R.G. Spratt, D.A. Carbonneau, and J.E. Waller TL when the distal end of the tail is missing as a result of past injury (Chabreck and Joanen 1979; Platt et al. 2009, 2011; Webb and Messel 1978). Variations in the methods used to determine HL (or skull length) in crocodilians are potential sources of confusion. For instance, HL has been defined as the distance from the tip of the snout to the quadrates (Dodson 1975), to the posterior edge of the supraoccipital plate (Eaton and Link 2011; Erickson et al. 2003; Platt et al. 2009, 2011), and to the posterior surface of the occipital condyle (Verdade 2000). FWC measures HL as the straight center-line measurement from the tip of the snout to the medial posterior margin of the cranial platform, or parietal bone, parallel to the dorsal surface of the skull (Fig. 3). Calipers or a metal tape should be used to ensure that a straight-line measurement is obtained at the appropriate angle. This method of measuring HL is consistent with “dorsal cranial length A” which was recently reported for a record-size Crocodylus porosus Schneider (Estuarine Crocodile), the largest crocodilian ever placed in captivity (Britton et al. 2012). Head length is important because it is highly correlated with TL (Platt et al. 2009, 2011; Woodward et al. 1995), and the skull of large alligators is often preserved, thus providing evidence that can substantiate records when no other physical evidence remains. An advantage of the method FWC uses to measure HL is that it can be applied to a head that has the skin intact, such as a taxidermy-mounted specimen. FWC measures TG (circumference) with a nylon tape at the anterior margin of the third row of scales posterior to the hind legs (Fig. 4). Tail girth can provide perspective on an alligator’s physical condition and, combined with TL, can be used to estimate the weight of an alligator (Woodward et al. 1992). Weight is recorded with a calibrated scale, with the level of precision noted. Sex of alligators is determined by inserting a finger into the cloaca to determine the presence or absence of a penis (Chabreck 1963, Viosca 1939). On 1 November 2010, we measured and confirmed the longest alligator that has been measured and verified under the established protocol in Florida (Fig. 5). The alligator had a complete tail (i.e., not shortened due to injury), and its TL was 435.5 cm (14 ft 3.5 in). The alligator was harvested by a hunter during the statewide harvest on Lake Washington, a naturally wide section of the St. Johns River in Brevard County. Although this is the state’s longest alligator on record, it weighed only 296.5 kg (654 lbs), which is considerably less than the heaviest wild alligator officially verified in Florida (473.0 kg [1043 lbs]). It is the lightest of the 5 longest alligators recorded in Florida (Table 1). The physical appearance of the alligator seemed characteristic of an older animal that might have been in declining health. Its TG was undersized (TG = 91.0 cm) relative to other alligators of similar TL, and Figure 2. The standard snout–vent length (SVL) measurement of an American Alligator is the straight-line distance from the tip of the snout to the posterior margin of the cloacal vent. 2013 Southeastern Naturalist Notes Vol. 12, No. 4 N12 A.M. Brunell, J.P. Delaney, R.G. Spratt, D.A. Carbonneau, and J.E. Waller many of its teeth were heavily worn or missing. Condition has been defined for crocodilians as the relative mass of individual animals (Taylor 1979), and reduced TG typically indicates reduced body mass, or condition, for alligators of similar size (Woodward et al. 1992). Erickson (1996) concluded that senescence contributes, in part, to lack of replacement of missing teeth in alligators, but that dental trauma was the major cause of poor tooth replacement. Although not necessarily an indication of age or health, the alligator also had a soft tissue mass, approximately 10 × 7 cm, protruding from an area near the right oral Figure 3. The standard head length (HL) measurement of an American Alligator is the straight centerline distance from the tip of the snout to the medial posterior margin of the cranial platform, or parietal bone, as shown in the overhead view (A). The side view (B) shows that the measurement should be taken parallel to the surface of the skull. N13 2013 Southeastern Naturalist Notes Vol. 12, No. 4 A.M. Brunell, J.P. Delaney, R.G. Spratt, D.A. Carbonneau, and J.E. Waller commissure. This soft tissue mass appeared to be displaced tissue from an old injury (Dan Wolf and Mark Cunningham, FWC, Gainesville, FL, pers. comm.). This was only the third alligator in Florida officially verified to equal or exceed 426.5 cm TL (14 ft; Table 1). The first was harvested on 5 June 1989 by a nuisance-alligator trapper on the Apalachicola River in Franklin County in the Florida panhandle. The measured TL for that animal was 426.5 cm (14 ft 0.0 in). On 30 September 1997, another nuisancealligator trapper harvested an alligator measuring 428.0 cm (14 ft 0.5 in) from Lake Monroe on the St. Johns River in central Florida. That specimen stood as the state’s longest alligator until the current record animal was harvested from Lake Washington in 2010. Although there have been claims of larger alligators in Florida since FWC began keeping official records, none have been confirmed. The possibility that a larger alligator was harvested and not officially verified seems unlikely, given the time between records, the tendency of hunters to want to claim credit for large specimens, and the potential market value of a record alligator. Additionally, the likelihood of a larger alligator diminishes as male alligators reach their upper limit of asymptotic size of approximately 400–420 cm (Chabreck and Joanen 1979, Rootes et al. 1991, Wilkinson and Rhodes 1997). With over 20,000 alligators harvested from the wild each year (Florida Fish and Wildlife Conservation Commission 2011), it is clear that alligators in Florida rarely reach lengths ≥400 cm (13 ft 1.5 in). This, in part, may be a result of harvests removing larger alligators before they are able to attain their maximum length. We contacted other state wildlife agencies in the southeastern US that have alligator populations, and requested information about the largest alligators they had on record. Although we were unable to ascertain when all of the states began keeping official records, most appear to coincide with the initiation of the states’ alligator-hunting programs. Alabama, Mississippi, and Texas are the only states other than Florida to have verified TL measurements ≥400 cm. The record for Mississippi Figure 4. The standard tail girth (TG) measurement of an American Alligator is the circumference of the tail at the anterior margin of the third transverse row of scales posterior to the hind legs. 2013 Southeastern Naturalist Notes Vol. 12, No. 4 N14 A.M. Brunell, J.P. Delaney, R.G. Spratt, D.A. Carbonneau, and J.E. Waller Figure 5. Florida’s record-length American Alligator that was taken by Robert Ammerman (shown in picture) on 1 November 2010. The alligator’s total length was 435.5 cm (14 ft 3.5 in), measured as the straight-line distance from the tip of the snout to the tip of the tail by FWC biologists. Table 1. Body measurements of the five longest male American Alligators in Florida that have been verified by FWC biologists. All length measurements (TL = total length, SVL = snout–vent length, TG = tail girth, and HL = head length) are reported to the nearest 0.5 cm. All alligators in this table had complete tails with no missing length. Weight (WT) is given in kg. Date Harvest location TL SVL TG HL WT 1-Nov-2010 Lake Washington, Brevard Co. 435.5 229.0 91.0 59.5 296.5 30-Sep-1997 Lake Monroe, Seminole Co. 428.5 223.5 106.5 57.0 363.0 5-Jun-1989 Apalachicola River, Franklin Co. 427.0 - - 60.0 324.0 19-Sep-2001 Kovacs Bros. Ranch, Polk Co. 425.0 216.5 118.0 57.0 399.0 17-Apr-1989 Orange Lake, Alachua Co. 423.0 218.5 132.0 58.5 473.0 N15 2013 Southeastern Naturalist Notes Vol. 12, No. 4 A.M. Brunell, J.P. Delaney, R.G. Spratt, D.A. Carbonneau, and J.E. Waller was a 413.0-cm (13 ft 6.5 in) alligator taken in 2008 (Ricky Flynt, Mississippi Department of Wildlife, Fisheries, and Parks, Jackson, MS, pers. comm.). Texas reported four alligators ≥400 cm (Amos Cooper, Texas Parks and Wildlife Department, Port Arthur, TX, pers. comm.). The longest Texas alligator had a TL of 434.5 cm (14 ft 3.0 in) and was harvested in 2013. Alabama verified 11 alligators ≥400 cm, including 3 that were >426.5 cm (14 ft) (Ray Metzler, Alabama Division of Wildlife and Freshwater Fisheries, Montogomery, AL, pers. comm.). Alabama’s official record for TL was 432.0 cm (14 ft 2.0 in) taken from two alligators. One was harvested in 2011 and the other in 2012. The third Alabama alligator to exceed 426.5 cm measured 429.0 cm (14 ft 1.0 in) and was also harvested in 2012. The records for Arkansas and North Carolina were 404.0 cm (13 ft 3.0 in) and 382.0 cm (12 ft 6.0 in), respectively (Kelly Irwin, Arkansas Game and Fish Commission, Benton, AR; Jeff Beane, North Carolina State Museum of Natural Sciences, Raleigh, NC, pers. comm.). Texas, Arkansas, and North Carolina indicated that their TL records are straightline measurements similar to FWC’s protocol. Alabama and Mississippi indicated that their TL records are based on over-the-back measurements. South Carolina does not officially measure alligators harvested during its public hunts, but has kept length records obtained from research activities. The longest confirmed alligator in South Carolina was 399.0 cm (13 ft 1.0 in; Jay Butfiloski, South Carolina Department of Natural Resources, Columbia, SC, pers. comm.). Oklahoma, Georgia and Louisiana do not keep official records of large alligators (Richard Beagles, Oklahoma Department of Wildlife Conservation, Idabel, OK; Greg Waters, Georgia Department of Natural Resources, Fitzgerald, GA; Ruth Elsey and Noel Kinler, Louisiana Department of Wildlife and Fisheries, Grand Chenier and New Iberia, LA, pers. comm.). The fascination with large crocodilians is a likely factor contributing to exaggerated claims of unusually large specimens. In many cases, these claims cannot be substantiated due to the lack of physical evidence. McIlhenny’s (1935) claim of a 584-cm (19 ft 2 in) alligator is one of those cases. Despite the questionable nature of this record, it continues to be presented as fact in literature, such as Conant and Collins’ (1998) popular field guide. Those managing and researching crocodilians should be cautious about accepting unusual records with insufficient physical evidence and documentation of how data were collected. When available, physical evidence such as a skull should be critically assessed in light of proven allometric relationships to determine the likelihood of the claim (Greer 1974, Whitaker and Whitaker 2008, Woodward et al. 1995). Standardized measuring protocols are an important tool for validating and comparing measurements of large alligators. We have found that our protocol ensures that the most important data are collected and reported in a standardized fashion that allows for direct comparisons among alligators. Collection of morphometric data from the largest specimens provides additional information on allometric relationships that are often poorly understood due to the rarity of such large animals. It is also important to communicate to constituents the standards and means for officially recognizing record alligators. Without this information, some specimens might go unreported because the hunter does not care or is not aware of the process for obtaining official recognition. The current record-length alligator, as well as previous Florida records, were officially recognized because the hunters contacted FWC in a timely manner prior to processing the animal. Efforts by the FWC to validate the measurements of record-sized alligators have produced credible data and minimized the conjecture that often occurs in the absence of data validation. We recommend that all states in the range of the American Alligator establish consistent standards for recognizing and recording record-size specimens 2013 Southeastern Naturalist Notes Vol. 12, No. 4 N16 A.M. Brunell, J.P. Delaney, R.G. Spratt, D.A. Carbonneau, and J.E. Waller across the species’ range. These standards can increase the credibility of reports of unusually large specimens and improve the quality of data, leading to a better understanding of the life history of the species. Furthermore, accurate and credible records can promote a more knowledgeable public and help maintain the reputation of agencies as reliable sources for science-based information. Acknowledgments. The authors thank Allan Woodward (FWC) for his insight and guidance. We are grateful to Ginny Canady (Medical University of South Carolina) for providing the measurement illustrations and to Louis Guillette (Medical University of South Carolina) for his efforts to assist with this manuscript. Allan Woodward and Tim O’Meara (FWC) reviewed and provided comments on the manuscript. Literature Cited Britton, A.R.C., R. Whitaker, and N. Whitaker. 2012. Here be a dragon: Exceptional size in a Saltwater Crocodile (Crocodylus porosus) from the Philippines. Herpetological Review 43:541–546. Buckner, E.L., and J. Reneau. 2009. Measuring and Scoring North American Big Game Trophies. 3rd Edition. Boone and Crockett Club, Missoula, MT. 176 pp. Chabreck, R.H. 1963. Methods of capturing, marking, and sexing alligators. Proceedings of the Southeastern Association of Game and Fish Commissions 17:47–50. Chabreck, R.H., and T. Joanen. 1979. Growth rates of American Alligators in Louisiana. Herpetologica 35:51–57. Conant, R., and J.T. Collins. 1998. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. 3rd Edition, Expanded. Houghton Mifflin Publishers, Bos ton, MA. 620 pp. David, D.N., A.M. Brunell, D.A. Carbonneau, H.J. Dutton, L.J. Hord, E.N. Wiley, and A.R. Woodward. 1996. Florida’s alligator management program: An update: 1987 to 1995. Pp. 410–428, In Crocodiles. Proceedings of the 13th Working Meeting of the Crocodile Specialist Group. IUCN— The World Conservation Union, Gland, Switzerland, 516 pp. Dodson, P. 1975. Functional and ecological significance of relative growth in Alligator mississippiensis. Journal of the Zoological Society of London 175:315–355. Dutton, H.J., A. Brunell, D. Carbonneau, L. Hord, S. Stiegler, C. Visscher, J. White, and A. Woodward. 2002. Florida’s alligator management program: An update 1987–2001. Pp. 23–30, In Crocodiles. Proceedings of the 16th Working Meeting of the Crocodile Specialist Group. IUCN—The World Conservation Union, Gland, Switzerland, 416 pp. Eaton, M.J., and W.A. Link. 2011. Estimating age from recapture data: Integrating incremental growth measures with ancillary data to infer age-at-length. Ecological Applications 21:2487–2497. Erickson, G.M. 1996. Toothlessness in American Alligators, Alligator mississippiensis. Copeia 3:739–743. Erickson, G.M., A.K. Lappin, and K.A. Vliet. 2003. The ontogeny of bite-force performance in American Alligator (Alligator mississippiensis). Journal of the Zoological Society of London 260:317–327. Florida Fish and Wildlife Conservation Commission. 2011. Estimated producer value of wild alligator harvests in Florida during 1977–2010. Available online at http://myfwc.com/media/310314/ alligator_wild_value.pdf. Accessed 17 May 2012. Greer, A.E. 1974. On the maximum total length of the Salt-water Crocodile (Crocodylus porosus). Journal of Herpetology 8:381–384. Mazzotti, F.J., and L.A. Brandt. 1994. Ecology of the American Alligator in a seasonally fluctuating environment. Pp. 485–505, In S.M. Davis and J.C. Ogden (Eds.). Everglades: The Ecosystem and Its Restoration. St. Lucie Press, Delray Beach, FL. 860 pp. McIlhenny, E.A. 1935. The Alligator’s Life History. Christopher Publishing House, Boston, MA. 117 pp. Platt, S.G., T.R. Rainwater, J.B. Thorbjarnarson, A.G. Finger, T.A. Anderson and S.T. McMurry. 2009. Size estimation, morphometrics, sex ratio, sexual size dimorphism, and biomass of Morelet’s Crocodile (Crocodylus moreletii) in northern Belize. Caribbean Journal of Science 45:80–93. N17 2013 Southeastern Naturalist Notes Vol. 12, No. 4 A.M. Brunell, J.P. Delaney, R.G. Spratt, D.A. Carbonneau, and J.E. Waller Platt, S.G., T.R. Rainwater, J.B. Thorbjarnarson, and D. Martin. 2011. Size estimation, morphometrics, sex ratio, sexual size dimorphism, and biomass of Crocodylus acutus in the Coastal Zone of Belize. Salamandra 47:179–192. Rhodes, W.E. 2002. Differential harvest of American Alligators on private lands in coastal South Carolina. Pp. 75–79 In Crocodiles. Proceedings of the 16th Working Meeting of the Crocodile Specialist Group. IUCN—The World Conservation Union, Gland, Switzerland, 416 pp. Rootes, W.L., R.H. Chabreck, V.L. Wright, B.W. Brown, and T.J. Hess. 1991. Growth rates of American Alligators in estuarine and palustrine wetlands in Louisiana. E stuaries 14:489–494. Taylor, J.A. 1979. The foods and feeding habits of subadult Crocodylus porosus Schneider in Northern Australia. Australian Wildlife Research 6:347–359. Verdade, L.M. 2000. Regression equations between body and head measurements in the Broadsnouted Caiman (Caiman latirostris). Revista Brasileira de Biologia 60:469–482. Viosca, P., Jr. 1939. External sexual differences in the alligator, Alligator mississippiensis. Herpetologica 1:154–155. Webb, J.W., and H. Messel. 1978. Morphometric analysis of Crocodylus porosus from the north coast of Arnhem Land, Northern Australia. Australian Journal of Zoology 26:1–27. Whitaker, R., and N. Whitaker. 2008. Who’s got the biggest? Crocodile Specialist Group Newsletter 27:26–30. Wilkinson, P.M., and W.E. Rhodes. 1997. Growth rates of American Alligators in coastal South Carolina. Journal of Wildlife Management 61:397–402. Woodward, A.R., C.T. Moore, and M.F. Delany. 1992. Experimental alligator harvest. Final Report. Study Number 7567. Florida Game and Fresh Water Fish Commission, Gainesville, FL. 118 pp. Woodward, A.R., J.H. White, and S.B. Linda. 1995. Maximum size of the alligator (Alligator mississippiensis). Journal of Herpetology 29:507–513.