Growth dynamics in the American alligator (Alligator mississippiensis)

Abstract

With 7 figures in the text)The growth dynamics of the American alligator (Alligator mississippiensis) were studied in the subtropical Florida Everglades using extensive mark-recapture data from over 2000 recaptures of known-aged and unknown-aged animals. A model based on the power curve best describes growth of Everglades alligators. The nonasymptotic character of this curve leads to rejection of the hypothesis that alligator growth is determinate. A model consisting of piece-wise linear equations better described growth in the first year, and suggested a period of arrested growth occurred in the first winter. A comparison of predictions from growth models derived from several populations indicated that Everglades alligators grew more slowly than did those in more temperate areas, leading to the rejection of the hypothesis that growth rates in subtropical Florida would be elevated because of the long growing season. We attribute this result to a combination of increased maintenance costs and a limited resource base in the Everglades.

Annual and seasonal survival of adult female Mottled Ducks in southern Florida, USA

“…Relative body size was then employed as an estimate of relative age and skeletal maturity. Estimates of relative ages based on total body length may be unreliable for Alligator, however, due to potential variation in size and/or growth rates between sexes and among habitats and geographical regions (McIllheny, 1935;Peabody, 1961;Bellairs, 1970;Andrews, 1982;Jacobsen and Kushlan, 1989;Magnussen et al, 1989;Castanet et al, 1993;Dalrymple, 1996;Wilkinson and Rhodes, 1997). Sex and geographical region were known for the majority of the study sample; variation due to other factors could not be controlled for in the collections examined.…”

“…These may include sexual dimorphism; seasonally interrupted growth; environmental conditions of habitat, diet, and temperature; and indeterminate growth (McIllheny, 1935;Peabody, 1961;Bellairs, 1970;Andrews, 1982;Jacobsen and Kushlan, 1989;Magnussen et al, 1989;Castanet et al, 1993;Dalrymple, 1996;Wilkinson and Rhodes, 1997;Elsey et al, 2000;. To the extent possible, effort was made to control for these variables within sizebased analyses of the study sample.…”

“…Farm-raised individuals all exhibit texture Types III and IV; however, this distribution is consistent with that of wild and captive individuals of similar size. Previous studies of Alligator growth have concluded that growth rates vary throughout the species' geographical range due to local environmental conditions and resource availability (Jacobsen and Kushlan, 1989;Dalrymple, 1996;Wilkenson and Rhodes, 1997). It may therefore be fruitless to employ size as an age proxy for a sample drawn from diverse geographical areas.…”

“…The combination of these 2 marks can provide identification of over 3,000 individuals. Researchers, however, are increasingly marking alligators using individually numbered monel tags placed on webbing located between the toes , Jacobson and Kushlan 1989, allowing for an unlimited number of alligators to be marked and later identified.…”

Factors Influencing Movements and Foraging Ecology of American Alligators (Alligator mississippiensis) in a Dynamic Subtropical Coastal Ecosystem

“…Thus the turnover rates quantified in my study are some combination of growth turnover and catabolic turnover and may be faster than the turnover rates of adult alligators that, though they grow indeterminately (Jacobsen and Kushlan 1989), grow more slowly than juveniles. Both Reich et al (2008) and Murray and Wolf (2012) were able to partition isotope turnover rates into their growth and catabolic turnover components using exponential growth models based on changes in body mass.…”