Caiman yacare

Important synonyms: Caiman crocodilus yacare Common names: Yacaré, Jacaré, Lagarto, Yacaré negro, Yacaré tinga Range: Argentina, Brazil, Bolivia, Paraguay Revised by Eduardo Espinosa

CITES: Appendix II
CSG Action Plan: Availability of Survey Data – Adequate
Need for Wild Population Recovery – Moderate
Potential for Sustainable Management – Highest
1996 IUCN Red List: Not Listed (LRlc Lower Risk, least concern. Widespread and numerous populations, although locally depleted.)
Principal threats: Illegal hunting, habitat destruction.

Ecology and natural history

The yacaré caiman is found in southern Brazil and Bolivia, southwards through the Paraguay/Paraná River systems and into northern Argentina. Morphologically and ecologically this species is very similar to the common caiman, and similarly can be found in a wide spectrum of habitat types. Most of the ecological studies on this species have been carried out in the Pantanal region of southern Brazil (Crawshaw and Schaller 1980, Schaller and Crawshaw 1982, Cintra 1986). More recent studies also include Bolivia (Pacheco 1993a, Godshalk 1994). Nesting habitats were monitored during the incubation and hatching period (Borges and Filho 1993), and the effect of water level on hatchlings survivorship have also been evaluated (Continho 1993). Aerial surveys of caiman nests have been started in the Pantanal (Mourao et al. 1994).

Although often considered a subspecies of Caiman crocodilus, the yacaré occupies a distinct geographic range and a special position in the international skin trade and is therefore treated separately here for convenience. Resolution of the systematic relationships within the very widespread Caiman crocodilus complex is needed. Extensive surveys and specimen collection in southern Brazil, northern Bolivia and Paraguay suggest a very complex gradient of morphological features between C. crocodilus and the yacaré. Analyses of mitochondrial DNA to resolve the relationships between these taxa are incomplete and inconclusive (Brazaitis et al. 1993).

Yacaré caiman are mound nesters, with egg-laying usually peaking in the middle wet season. Clutch size is typically in the 25–35 range. The natural tendency of females to guard their nests is apparently influenced by human hunting pressure (Crawshaw 1987), which results in decreased nest attendance and a lower hatching success. Detailed information is now available on the ecology of the species in the Brazilian Pantanal from the work of Campos, Mourao and colleagues (Campos 1993, Mourao et al. 1994, Campos and Magnusson 1995, Campos et al. 1995, Mourao et al. 1996, Santos et al. 1996, Couthino and Campos 1996).

Conservation and status

Most of what is written about the conservation of the common caiman applies equally well to this species. Basic survey information is available for this species in all countries where it occurs. This information has resulted principally from a series of CITES sponsored surveys of southern Brazil, Bolivia, and Paraguay. Populations of yacaré caiman are considered to be somewhat depleted in all four countries where it occurs, and this is principally due to widespread illegal hunting during the 1970s and 1980s. Poaching remains a problem throughout much of this species’ range, particularly in Brazil (Brazaitis et al. 1988, Brazaitis 1989). However, due to their small size at maturity, their ability to adapt to a wide variety of habitat types, and their learned wariness, caiman are particularly resilient to hunting pressure. Recent analyses in Brazil suggest that the hunting pressure, while illegal, has not negatively impacted populations and may be sustainable (Mourao et al. 1996). Surveys in Paraguay (Scott et al. 1990, King, Aquino, Scott and Palacios 1994) and Argentina (Waller and Micucci 1993) indicate that extensive populations remain or have recovered from previous exploitation since the closure of uncontrolled exploitation and implementation of export controls.

Commercially oriented management programs are in place in three of the four countries for yacaré. Paraguay is moving toward sustainable management (King, Aquino, Scott and Palacios 1994) and permitted an experimental export quota of 5,000 in 1994. Cropping was permitted in Bolivia, where hides were exported under a CITES quota until a ban was instituted in 1989. Recently, new surveys were initiated and a controlled hunting program similar to the Venezuelan program has been proposed (Godshalk 1994). In Brazil, hunting of wild animals is not permitted, but ranching and farming programs are developing rapidly. Captive breeding farms have proliferated and Brazilian regulations require that all caiman skins must be produced on farms, be tagged, semiprocessed to the ‘wet blue’ stage and have a minimum belly width of 18cm (TRAFFIC 1994). An experimental ranching system is being developed in the Pantanal. In Argentina, a plan for the captive rearing of yacaré for reintroduction is still underway, which hopefully may be as successful as the program for Caiman latirostris (Larriera 1993). Studies on distribution, habitat characterization and habitat availability of yacaré have been already conducted in the province of Corrientes (Waller and Micucci 1993). A second phase of studies is required to define management alternatives for yacaré in this region of Argentina.

Priority projects

High priority

Implementation of management programs in Brazil: Brazil has undertaken a very rapid development of captive breeding (farming) of caiman similar to that in Colombia. A number of facilities are registered with the government and CITES as captive breeding facilities and are producing skins for export. Unfortunately little conservation benefit is resulting from these activities. There is a need to develop government regulatory and management capacity and provide a linkage to protection of wild caiman populations and their habitats.

Control of illegal trade in Caiman yacare skins: This project is as described in this volume for Caiman crocodilus.

Study of Caiman systematics: To clarify the complex taxonomic situation of yacaré, molecular techniques employing the D-loop of the control region of the mitochondrial DNA could be used to determine genetic relationships among subspecies because of its higher resolution (Avise 1994). The use of this region allows more accurate differentiation at a lower taxonomic level (species or subspecies rather than families) than other studies to date. Parallel studies of morphological variation, particularly in areas of intergradation are also needed.

Moderate priority

Long-term ecological studies in the Pantanal, Brazil: Like the llanos of Venezuela and Colombia, the Pantanal is a large seasonally inundated savanna that offers excellent research opportunities for the study of caiman population dynamics. The interest in the development of sustainable management programs should foster the development of research programs to investigate aspects of the life history of the yacaré.

Implementation of management program in Paraguay: A survey conducted by King, Aquino, Scott and Palacios. (1994) encountered numerous populations of yacaré. That report’s recommendations provide the basis for a sustainable utilization program for the species. At the beginning the hunting activity should be restricted to the Alto Paraguay. A continuous monitoring program to evaluate the status of the population, particularly under exploitation, will be also important to ensure the sustainability of the program.

Yacaré, Caiman yacare. This widespread species remains abundant in the Pantanal of Brazil.
Photo by R. S. Funk.