The American Crocodile is a large species of crocodilian, with males attaining maximum lengths of 5-6 m, although some individuals may reach 7 m (Schmidt 1924; Medem 1981). Adult females generally measure no more than 3-3.5 m TL, but individuals up to 4.4 m have been reported (Domínguez-Laso 2009). Sexual size dimorphism indices of 2.10, 2.13, 2.09, 2.08, and 2.13 were calculated for populations in coastal Belize and the Caribbean coast of Mexico (Platt et al. 2011; Labarre et al. 2017). Both sexes exhibit a pronounced median pre-orbital ridge (POR) on the skull, which may be sexually dimorphic and appears to vary geographically among C. acutus populations (Thorbjarnarson 1989; Platt and Rainwater 2005). The American Crocodile is characterized by the most reduced and irregular dorsal armour (osteoderms) of any crocodilian (Ross and Mayer 1983). Inter-populational differences in scalation likely exist in this widely ranging species (Seijas 2002; Platt et al. 2012), and recent studies have also shown high intraspecific variation in the post-occipital, cervical, and dorsal scalation, allowing for individual identification (Balaguera-Reina et al. 2017). Population-specific size estimation models for C. acutus are available for Belize (Platt et al. 2011), Mexico (Labarre et al. 2017), and Coiba Island, Panama (Balaguera-Reina et al. 2018b).  

The habitat of C. acutus consists largely of brackish water coastal habitats such as the saltwater sections of rivers, coastal lagoons, and mangrove swamps. Crocodylus acutus inhabits offshore cays (islands) and atolls where it survives under true marine conditions (Platt and Thorbjarnarson 2000a; Platt et al. 2013; Charruau et al. 2005; González Cortés 2007; Venegas-Anaya et al. 2015). Populations are also known from freshwater habitats located well inland, including a number of reservoirs (Medem 1981; Mandujano-Camacho and Rodas-Trejo 2010; Sigler 2010; Espinal and Escobedo-Galván 2011). A significant population inhabits Lago Enriquillo, a landlocked hypersaline lake situated 40 m below sea level in the arid southwestern Dominican Republic (Schubert 2002). A robust population also inhabits Cayo Centro, an island in Banco Chinchorro atoll located 50 km from southern coast of the Mexican state of Quintana Roo. During the dry season, lagoons on Cayo Centro can experience extremely hypersaline conditions (up to 61 ppt; Charruau et al. 2005).   

Knowledge on C. acutus has increased rapidly over the few past decades, and much research has been conducted on reproductive ecology (Platt and Thorbjarnarson 1997, 2000b; Mazzotti et al. 2007a; Charruau et al. 2010a, 2011; 2017a; Escobedo-Galván et al. 2019; Platt et al. 2014a; Charruau 2012; Charruau and Hénaut 2012; Balaguera-Reina et al. 2015a; Murray et al. 2015, 2016; González-Desales et al. 2016; Ferguson et al. 2017; Gómez-González et al. 2017), nutrition, diet, and foraging ecology (Platt et al. 2002, 2013a, b, 2014b, Richards and Wasilewski 2003; Gómez Hernández 2004; Cupul-Magaña et al. 2008, 2015; Villegas and Schmitter-Soto 2008; Ávila Cervantes et al. 2017; Hernández-Hurtado et al. 2018; Balaguera-Reina et al. 2018a; Triminio et al. 2019), morphometrics (Domínguez-Laso 2009; Platt et al. 2011; Platt and Rainwater 2005; Rainwater et al. 2010; Domínguez-Laso 2017; Labarre et al. 2017), scalation (Seijas 2002; Platt et al. 2012; Balaguera-Reina et al. 2017; Boucher et al. 2017; English 2017), growth (Pérez and Escobedo-Galván 2009; Charruau 2011; Charruau et al. 2010b; García-Grajales et al. 2012, Balaguera-Reina et al. 2015a), movement and spatial ecology (Wheatley et al. 2012; Cherkiss et al. 2014; Balaguera-Reina et al. 2016; Beauchamp et al. 2018; Farlow et al. 2018a, b; Beauchamp et al. 2019), population genetics (Ray et al. 2004; Cedeño-Vázquez et al. 2008; Porras Murillo et al. 2008; Rodriguez et al. 2008, 2011; Weaver et al. 2008; Machkour-M’Rabet et al. 2009; Milián-García et al. 2011, 2015; González-Trujillo et al. 2012; Bashyal et al. 2014; Bloor et al. 2015, Budd et al. 2015; Hekkala et al. 2015; Pacheco-Sierra et al. 2016; Serrano-Gómez et al. 2016; Mauger et al. 2017; Milián-García et al. 2018a, b; Pacheco-Sierra et al. 2018), behavior in captivity (Benko and Perc 2009); physiology and biochemistry (Merchant et al. 2010a, b), parasitology and bacteriology (Villegas and Gonzáles-Solís 2009; Pérez-Flores et al. 2011, 2017; Tellez and Paquet-Durand 2011; Charruau et al. 2012, 2016, 2017b; Escobedo-Galván et al. 2012; Charruau and González-Muñoz 2015; Rainwater et al. 2015; Reeves et al. 2019), ecotoxicology (Wu et al. 2000; Rainwater et al. 2007, 2011; Charruau et al. 2013; Murray et al. 2017), and conflict with humans (Barrantes 2010; Cupul-Magaña et al. 2010; Balaguera-Reina 2012, 2013; Bolaños Montero, 2012; García-Grajales and Buenrstro-Silva 2013; García-Grajales et al. 2013; Carrillo-Rivera and Porras-Murillo 2014; Ponce-Campos 2014; Balaguera-Reina and Farfán-Ardila 2018; García-Grajales and Buenrostro-Silva 2018, 2019).

Crocodylus acutus is a hole-nesting species, but adaptable in terms of nesting ecology, in some areas creating elevated mounds of substrate into which eggs are deposited (Thorbjarnarson 1989; Platt and Thorbjarnarson 1997; Platt and Thorbjarnarson 2000b; Charruau et al. 2010a, 2011). Clutch size is typically 30 to 60 eggs, although in some populations mean clutch size is in the low 20s (Platt and Thorbjarnarson 2000b, Sigler 2010; Balaguera-Reina et al. 2015a) or less (i.e. <17 at Banco Chinchorro; Charruau et al. 2010a). As with most hole nesting species of crocodilians, C. acutus nests during the annual dry season, with eggs hatching around the beginning of the annual wet season (Thorbjarnarson 1989; Platt and Thorbjarnarson 2000b, Sigler 2010; Balaguera-Reina et al. 2015a; Casas-Andreu 2003; Charruau et al. 2011; González-Desales et al. 2016). A somewhat different pattern occurs in Banco Chinchorro atoll where the population has adapted to local conditions. Females nest at the end of the dry season and hatching occurs during the middle of the wet season, thus representing a compromise between the risk of flooding and increasing the availability of freshwater for hatchlings (Charruau et al. 2010a). Most nest failures are attributed to predation, nest abandonment, desiccation, flooding, and low temperatures associated with heavy rainfall (Mazzotti 1989; Platt and Thorbjarnarson 2000b; Charruau et al. 2010a). The American Crocodile is adept at using man-made areas for nesting, and this is one of the reasons behind population recovery in parts of its range (Mazzotti et al. 2007a, 2009; Ulloa Delgado 2012; McCann et al. 2016; Mazzotti et al. 2019).  

Similar to most crocodilians, C. acutus is a dietary generalist that consumes a wide variety of prey such as invertebrates, amphibians, reptiles, birds and mammals (Platt et al. 2013a; Balaguera-Reina et al. 2018a). In offshore, marine habitats of Belize, Mexico (Quintana Roo), and Panama, the diet consists largely of marine invertebrates, particularly various species of crabs, but also corals, gastropods, and bivalves (Platt et al., 2013a, Ávila Cervantes et al. 2017; Balaguera-Reina et al. 2018a). Fruit and vegetation are occasionally consumed by C. acutus, although the dietary significance of frugivory is poorly understood (Platt et al., 2013b, 2014b). Crocodylus acutus exhibits the typical ontogenetic dietary shift with smaller size-classes consuming mostly invertebrates and larger individuals taking increasing amounts of vertebrate prey (Platt et al. 2002, 2013a; Balaguera-Reina et al. 2018a).  

Studies on the population ecology of C. acutus have been carried out in Belize (Platt et al. 1999, 2004; Platt and Thorbjarnarson 2000a; Platt 2003; Rainwater and Platt 2009, 2013; Chenot-Rose and Rose 2013; Platt and Rainwater 2014, Tellez et al. 2016), Colombia (Balaguera-Reina and Gonzalez-Maya 2008; Ulloa Delgado 2011; Balaguera-Reina 2012; Balaguera-Reina et al. 2012, 2015b, 2016; Espinosa et al. 2012, Viloria-Largares et al. 2017), Costa Rica (Bolaños Montero, 2012; Mauger et al. 2012), Cuba (Rodríguez Soberón et al. 2002), Dominican Republic (Schubert 2002; Powell and Incháustegui 2009), Ecuador (Carvajal et al. 2005), Haiti (Thorbjarnarson 1988), Honduras (Espinal and Escobedo-Galván 2011), Jamaica (Henriques et al. 2012), Mexico (Cupul-Magaña et al. 2004; Charruau et al. 2005; Cedeño-Vázquez et al. 2006; Hernández-Hurtado et al. 2006, 2011; Brandon-Pliego 2007; García-Grajales et al. 2007; González Cortés 2007; Sigler 2011; Garcia-Grajales and Buenrostro-Silva 2017), Panama (Venegas-Anaya et al. 2015, Balaguera-Reina et al. 2018b), the United States (Florida) (Ogden 1978, Kushlan and Mazzotti 1989a,b; Moler 1991; Moler and Abercrombie 1992; Mazzotti et al. 2007b; Cherkiss et al. 2011; Green et al. 2014; Lorenz 2014; Briggs-Gonzalez  et al. 2017), and Venezuela (Seijas 1988).

Recent genetic studies have confirmed that significant hybridization is occurring between C. acutus and C. moreletii in Belize (Hekkala 2004; Ray et al. 2004; Hekkala et al. 2015) and Mexico (Cedeño-Vázquez et al. 2008; Rodriguez et al. 2008; Machkour-M’Rabet et al. 2009; Pacheco-Sierra et al. 2016) as well as with C. rhombifer in Cuba (Weaver et al. 2008; Milián-Garcia et al. 2011, 2015). The ecological and evolutionary consequences of this hybridization are poorly understood but are a priority for future work.

The American Crocodile is the most widely distributed of the New World crocodiles and found in 18 countries in the northern Neotropics (Thorbjarnarson et al. 2006). Its range extends from the southern tip of Florida (USA), along both the Atlantic and Pacific coasts of southern Mexico, Central America, and northern South America, as well as the Caribbean islands of Cuba, Jamaica, and Hispaniola (Groombridge 1987, Kushlan 1988, Thorbjarnarson et al. 2006). An isolated subpopulation is found in the Rio Grijalva basin in Mexico. Along the Pacific coast, it extends from northern Sinaloa in Mexico to the limits of mangrove coastal habitats in northern Peru.

A review of the status and distribution of C. acutus throughout its range was carried out by Thorbjarnarson et al. (2006) and found the species to be recovering in most parts of its historic range. There were a few areas where population recovery appears to be limited (e.g. Colombia), or non-existent (e.g. Ecuador), but populations of C. acutus in areas such as Cuba, the USA and Costa Rica appear to be very healthy.

There are management measures in place in all countries where this species occurs, with the exception of El Salvador and Haiti. However, enforcement of protection is lacking and urgently needed, since illegal hunting remains a threat (Ross 1998). There are protected areas and sanctuaries for this species as well as captive breeding programmes and a few commercial farming operations are established. It is listed on Appendix I of CITES in most range states, and Appendix II in Mexico, Cuba and the Cispatá Bay population in Colombia. Further research into the population, habitat requirements, and threats to this species should be carried out, and population monitoring is recommended.

High priority

Thorbjarnarson et al. (2006) listed a number of specific areas containing some of the most important populations of C. acutus, and where greater habitat protection is needed. From this list, three areas have been selected here as the highest priority for conservation action.

1. Conservation in Peru and Ecuador: The Guayas River system in Ecuador historically supported a large population of C. acutus, which appears to have all but disappeared following intensive commercial hunting and habitat destruction in the 20th century. Surveys are needed to determine if crocodiles still remain in the Guayas River, and to develop population recovery plans. The small population in the Tumbes area of northern Peru is also extremely vulnerable. Preliminary studies suggest that the C. acutus in Ecuador/Peru are genetically distinct from other populations (M. Anaya-Venegas, pers. comm. 2018). Therefore, the genetic status of these populations merits further investigation.

2. Population evaluation and conservation in the Magdalena/Cauca River basin: Crocodiles are reported from several areas in the Magdalena/Cauca River basin up to 1200 km from the coast. This area is considered a high priority not only due to the lack of information and apparent endangered population status, but also because of the extraordinary riverine nature of the crocodiles. In a 2004 review by the CSG (Larriera et al. 2005), the implementation of a national program for rebuilding depleted populations of C. acutus was seen as a major priority and could be promoted by better linkage of commercial crocodile farming operations in Colombia with ex-situ conservation efforts (Larriera et al. 2005). However, these actions have not yet been carried out in Colombia, threatening the future of these populations.

3. Development of a conservation program in Jamaica: American Crocodile numbers continue to decline in Jamaica due to habitat loss, persecution, and illegal harvest for meat consumption (Henriques et al. 2012). Extirpation of the species in the country is likely unless effective conservation measures are taken (Henriques et al. 2012). A continued nation-wide population evaluation, habitat assessment, and monitoring and education program is needed as a foundation towards developing a crocodile conservation plan for Jamaica.

Moderate priority

4. Genetic evaluations: The American Crocodile is a wide-ranging and ecologically plastic species. Genetic evidence to date suggests there are substantial genetic differences among populations in different parts of the species’ range. American Crocodiles are known to hybridize with C. moreletii and C. rhombifer; however, the evolutionary implications of this hybridization are poorly understood, and further investigation is warranted.

5. Population status in the Cayman Islands, El Salvador, Guatemala, and Haiti: Recent information on the status of C. acutus in the Cayman Islands, El Salvador, Guatemala, and Haiti is sparse or lacking. Crocodile surveys in these countries are needed to assess population numbers, availability and quality of habitat, and current threats so that appropriate conservation and management plans can be developed.