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Caiman yacareYacare caiman

By Megan Flanagan

Geographic Range

Caiman yacare is mostly differentiated from Caiman crocodilus because of its habitat. Caiman crocodilus is the most widespread of the caiman species. Its range is from the Amazon rainforest in northern South America to Argentina. It is the most abundant crocodilian species in South America. (Campos, et al., 2014; Campos, et al., 2015; Ojeda, et al., 2017)

Habitat

Caiman yacare inhabits jungle areas with high precipitation. They are fixed around permanent bodies of water, typically swamps, wetlands, and rivers. They tend to nest within 200 meters of water or on mats of grass. Their nests move annually or more. When water levels are higher in the wet season and food resources are scarce, caiman tend to disperse in different spots along the water. If the dry season is especially harsh, many could perish with the lack of water available. ("Yacare Caimans", 2005; Campos, et al., 2015)

Physical Description

Caiman yacare used to be classified under Caiman crocodilus, but since has been classified as its own subspecies. Caimans can be distinguished from alligators by their divided eye ridges. It has brown to red colored scaly skin that is extremely valuable for hunters and poachers. The back of this animal is covered in dermal scutes, reaching up to several centimeters high. Another name for Caiman yacare is piranha caiman, because of their crooked teeth. They average about 76 cm for males and 70 cm for females, males being slightly larger and heavier than females. Sexual dimorphism can only be seen in young, as female caimans have much larger heads than males at a young age. Males are born much larger than females. Young also have more distinctive spots along their jaw than adults. (Azevedo and Verdade, 2011; Campos, et al., 2014; Encyclopedia of Life, 2015; Gray, 1862; Kofron and Farris, 2015; Mourão, et al., 1996; Piña, et al., 2007)

  • Sexual Dimorphism
  • male larger
  • Average mass
    58 Males, 14-23 Females kg
    lb
  • Average length
    2-2.5 Males, 1.4 Females m
    ft

Development

Caiman yacare lay eggs in mound nests. Incubation typically lasts 60-75 days. Sex is determined by temperature, but is usually impossible to determine when young are smaller than 30cm. Males are born much larger than females at birth. At the age of 10-15 years old, Caiman yacare reaches sexual maturity. (Campos, et al., 2014; Campos, et al., 2015; Campos, 1993)

  • Development - Life Cycle
  • temperature sex determination

Reproduction

There is very little research done on the mating systems of Caiman yacare, although the first major study has discovered the low genetic variance and multiple paternity in this species. They found that mostly dominant males contribute to reproduction. Usually, a female will use polyandry, and will choose several males to mate with. It is believed that females are also capable of sperm storage. Males will sometimes use the water dance used to communicate to attract mates. Females reach reproductive age around 10-15. (Campos and Mourão, 2014; Campos, et al., 2015; Campos, 1993; Ojeda, et al., 2017; Tarris, 2014)

Females guard the mound-shaped nests after eggs are laid. Typically, they nest within 200 m of water during the wet season. Clutch size is around 25. The incubation period usually lasts around 60-70 days. During this time, the female may leave the nest for short periods of time, exposing the eggs to predation. Usually, the nests are made on the shore or close by, or on mats of grass floating in the water. Grass mat nests help reduce the risk of predation drastically. (Campos and Mourão, 2014; Campos, et al., 2010; Campos, et al., 2015; Campos, 1993; Ojeda, et al., 2017; Tarris, 2014)

  • Breeding season
    Typically breed during wet season
  • Average number of offspring
    25
  • Range age at sexual or reproductive maturity (female)
    10 to 15 years
  • Range age at sexual or reproductive maturity (male)
    10 to 15 years

Female caiman yacare tend to guard nests after eggs are laid. After hatching, parental involvement ceases. ("Yacare Caimans", 2005)

  • Parental Investment
  • pre-hatching/birth
    • protecting
      • female

Lifespan/Longevity

The yacare caiman’s lifespan has not been extensively studied, but is estimated around 30 years. It is also estimated that they can live up to 50 years in captivity. ("Yacare Caiman", 2015; Campos, et al., 2014)

  • Range lifespan
    Status: captivity
    50 (high) days
  • Average lifespan
    Status: wild
    30 years

Behavior

Scientists have studied the infrasound and communications between Caiman yacare. This includes slapping of water, blowing bubbles, and making other noises to communicate. For longer distance communication, the yacare caiman uses infrasound, vibrating at a very low frequency, inaudible to humans, as well as a dance. There has been no long-term study of behavior of Caiman yacare. (Campos, et al., 2015; Kofron and Farris, 2015)

Communication and Perception

Vibrations, dancing and infrasounds are used for both mating displays and communications between yacare caimans. Dancing can include blowing bubbles and slapping water. "Water dances," when infrasound produces water disturbances, have not been exclusively studied for its purpose. No extensive research has been done on the senses of Caiman yacare (Kofron and Farris, 2015)

Food Habits

Since Caiman yacare lives near water, its diet is typically made up of aquatic invertebrates, mostly snails and fish. When eating snails, they will eat the shell as well as the animal itself. Foraging habits change with different climate conditions and availability of food sources. Since South America experiences wet and dry seasons, varying water levels affect accessibility to food sources. Many yacare caimans find food more accessible in the dry season with lower water levels. ("Yacare Caiman", 2015; "Yacare Caimans", 2005; Coutinho and Campos, 1996)

  • Animal Foods
  • fish
  • mollusks
  • aquatic crustaceans

Predation

There are few animals that prey on Caiman yacare, usually large mammals, such as the jaguar. There are, however, many that feed on the eggs of this caiman. When the mother leaves the nest for a short period of time, many small mammals take advantage of this gap to steal and eat the eggs. Common predators include the crab-eating fox, tayras, and feral pigs. Many yacare caiman nests are made on floating grass mats, drastically dropping the rate of predation on eggs. When nesting in the jungle near the water, predation levels are much higher. (Azevedo and Verdade, 2011; Campos and Mourão, 2014)

Ecosystem Roles

There is little mention of ecosystem roles in the literature, but one can infer its role from its dietary habits. It is a secondary consumer because it consumes snails and fish, but is eaten by larger mammals, like jaguars. It is a heterotrophic carnivore. ("Yacare Caiman", 2015; "Yacare Caimans", 2005; Coutinho and Campos, 1996)

Economic Importance for Humans: Positive

Caiman yacare has been coveted throughout time for their skin for making leather. It is now illegal to hunt these caimans, but is still prevalent. These hunters prefer larger caimans, usually around 80-90 cm. The 1980’s was the most popular time for this illegal harvest. There are many farms that legally raise these reptiles that gained popularity in the 90’s. It is still against the law to hunt Caiman yacare in the wild. Even though population numbers were very low, the laws put in place helped put its conservation status at least concerned. In addition to their valuable skin, their urine and meat are also marketable. Their urine is used in perfumes. (Carreira and Sabbag, 2015; Crocodile Specialist Group, 1996; Mourão, et al., 1996)

  • Positive Impacts
  • food
  • body parts are source of valuable material

Economic Importance for Humans: Negative

There is nothing present in the literature about negative impacts on humans. Caiman yacare lives deep in the jungle, usually hard to reach. (Campos, et al., 2015)

  • Negative Impacts
  • injures humans

Conservation Status

Despite the long history of illegal hunting of Caiman yacare, their conservation status is set at "least concerned." Before regulations, the status was "threatened," such as on the 1970 US Federal List. ("Yacare Caiman", 2015)

Contributors

Megan Flanagan (author), University of Wisconsin Stevens Point, Christopher Yahnke (editor), University of Wisconsin-Stevens Point, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

bog

a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.

carnivore

an animal that mainly eats meat

dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

food

A substance that provides both nutrients and energy to a living thing.

marsh

marshes are wetland areas often dominated by grasses and reeds.

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

piscivore

an animal that mainly eats fish

polyandrous

Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

sperm-storing

mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

threatened

The term is used in the 1994 IUCN Red List of Threatened Animals to refer collectively to species categorized as Endangered (E), Vulnerable (V), Rare (R), Indeterminate (I), or Insufficiently Known (K) and in the 1996 IUCN Red List of Threatened Animals to refer collectively to species categorized as Critically Endangered (CR), Endangered (EN), or Vulnerable (VU).

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

References

2015. "Yacare Caiman" (On-line). Conneticut's Beardsly Zoo. Accessed March 25, 2017 at http://www.beardsleyzoo.com/project_category/all-animals/page/8/.

2005. "Yacare Caimans" (On-line). Animal Corner. Accessed April 20, 2017 at https://animalcorner.co.uk/animals/yacare-caimans/.

Azevedo, F., L. Verdade. 2011. Predator–prey interactions: jaguar predation on caiman in a floodplain forest. Journal of Zoology, 286(2): 200-207. Accessed March 20, 2017 at http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.2011.00867.x/full.

Campos, Z., J. Mourão. 2014. Camera traps capture images of predators of Caiman crocodilus yacare eggs (Reptilia: Crocodylia) in Brazil’s Pantanal wetlands. Journal of Natural History, 49: 977-982. Accessed March 20, 2017 at http://www.tandfonline.com.ezproxy.uwsp.edu/doi/full/10.1080/00222933.2014.930757?scroll=top&needAccess=true.

Campos, Z. 1993. Effect of Habitat on Survival of Eggs and Sex Ratio of Hatchlings of Caiman crocodilus yacare in the Pantanal, Brazil. Journal of Herpetology, 27(2): 127-132. Accessed March 25, 2017 at http://www.jstor.org.ezproxy.uwsp.edu/stable/1564927?seq=2#page_scan_tab_contents.

Campos, Z., A. Llobet, C. Piña, W. Magnusson. 2010. Yacare Caiman Caiman yacare. Crocodiles . Status Survey and Conservation Action Plan, 3: 23-28. Accessed May 10, 2017 at http://www.iucncsg.org/365_docs/attachments/protarea/05_C-78894f16.pdf.

Campos, Z., G. Mourão, M. Coutinho, W. Magnusso. 2014. Growth of Caiman crocodilus yacare in the Brazilian Pantanal. PLoS One, 9(2): e89363. Accessed April 12, 2017 at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3938444/.

Campos, Z., G. Mourão, M. Coutinho, W. Magnusson, B. Soriano. 2015. Spatial and Temporal Variation in Reproduction of a Generalist Crocodilian, Caiman crocodilus yacare, in a Seasonally Flooded Wetland. PLoS One, 10(6): e0129368.. Accessed March 03, 2017 at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4481102/.

Carreira, L., O. Sabbag. 2015. Economic aspects of production of Caiman crocodilus yacare. Annals of the Brazilian Academy of Sciences, 87(1): 495-502. Accessed April 15, 2017 at http://www.scielo.br/pdf/aabc/v87n1/0001-3765-aabc-87-01-00495.pdf.

Coutinho, M., Z. Campos. 1996. Effect of Habitat and Seasonality on the Densities of Caiman in Southern Pantanal, Brazil. Journal of Tropical Ecology, 12(5): 741-747. Accessed March 26, 2017 at https://www.jstor.org/stable/2559977?seq=1#page_scan_tab_contents.

Crocodile Specialist Group, 1996. "IUCN Red List of Threatened Species" (On-line). Accessed February 03, 2017 at http://www.iucnredlist.org/details/46586/0.

Encyclopedia of Life, 2015. "Caiman Yacare" (On-line). Accessed May 10, 2017 at http://eol.org/pages/795539/details#size.

Gray, J. 1862. A synopsis of the species of Alligators. Journal of Natural History, 10(59): 327-331. Accessed February 16, 2017 at http://www.tandfonline.com/doi/abs/10.1080/00222936208681333?journalCode=tnah09&.

Kofron, C., P. Farris. 2015. Infrasound production by a yacare caiman Caiman yacare in the Pantanal, Brazil. Herpetology Notes, 8: 385-387. Accessed March 20, 2017 at http://www.biotaxa.org/hn/article/viewFile/10993/14651.

Mourão, G., M. Coutinho, Z. Campos. 1996. Size structure of illegally harvested and surviving caiman Caiman crocodilus yacare in Pantanal, Brazil. Biological Conservation, 75(3): 261-265. Accessed April 12, 2017 at http://www.sciencedirect.com/science/article/pii/0006320795000763.

Ojeda, G., P. Amavet, E. Rueda, P. Siroski, A. Larriera. 2017. Mating System of Caiman yacare (Reptilia: Alligatoridae) Described from Microsatellite Genotypes. Journal of Heredity, 108(2): 135-141. Accessed April 16, 2017 at https://academic.oup.com/jhered/article-lookup/doi/10.1093/jhered/esw080.

Piña, C., A. Larriera, P. Siroski, L. Verdade. 2007. Cranial sexual discrimination in hatchling broad-snouted caiman (Caiman latirostris). Iheringia. Série Zoologia, 97(1): 17-20. Accessed February 15, 2017 at http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0073-47212007000100003&lng=en&nrm=iso&tlng=en.

Tarris, J. 2014. "Jami Tarris Photo's" (On-line image). Accessed April 15, 2017 at http://jamitarris.photoshelter.com/image/I0000OwHQRRGVh5w.

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