Crocodiles belong to the family of reptiles, which almost always inspires fear in us. However, few of us know that by nature they are sociable beings, something rare in the reptile world.
Every August 23rd Mexico celebrates National Crocodile Day to raise awareness about the conservation of the species, which is one of the largest on the planet.
In the Mexican Republic, we can find three of the 23 species of crocodiles that exist on our planet:
River or real crocodile (Crocodylus acutus)
It lives in Tabasco. It is a species that reaches a length of 3 to 3.5 meters, and its young at birth measures between 25 and 30 centimeters. The head is flattened and wide. The snout is relatively short and quite rounded at the tip. Its length is 1.5 to 1.7 times the basal width.
Swamp crocodile (Crocodylus moreletii)
It is distinguished by its large size, usually 3 to 4 meters long. The elongated snout has five premaxillary teeth, 13 maxillary and 15 mandibular teeth, which gives it a powerful bite.
Caiman (Caiman crocodilus fuscus)
This species is the least known in the country; most of its population is found in the Encrucijada Reserve, in Chiapas. The caiman usually measures 2.5 meters in length. Its snout is wide and rounded. The upper and lower parts of the body are covered with an armor of dermal shields. The robust tail is laterally compressed and the toes of the legs are joined by membranes.
Crocodiles are excellent swimmers and can move on land by dragging their bodies. They can also propel themselves with their tail and attack vertically. They do not chew since they do not have cutting teeth. These only serve to hold and crush their prey. Another of their great abilities is the ability to climb trees when necessary.
Crocodiles are sociable animals
Crocodiles represent the reptiles with the highest level of socialization between individuals. Crocodile behavior can be classified into three main categories, which are maintenance, social interactions, and reproduction. Regarding social interactions, crocodile behavior depends on several factors, such as the level of overlapped territories of each individual, the season of the year, the sex of the animals, and movement tactics. In the species C. porosus, there is some stability in the overlap of individual territories.
Crocodiles are social animals with a wide range of ways to send signals. During mating and reproduction, competitive and antagonistic interactions are most obvious.
Male crocodiles tend to have a higher fidelity to their territories, where they establish stable social environments. On the other hand, young females and young males, which do not develop a strong attachment to a certain place, present more dynamic interactions. By looking at how crocodiles act in groups, scientists have been able to figure out and measure the spatial structures of both cryptic species, which share a habitat with other species, and solitary crocodiles.
The behavior of crocodiles in reproduction
Crocodile behavior is one of the most complex among reptiles. Many of their interactions with other individuals are motivated by sexual competition, resource competition, defense of territory, and the establishment of hierarchies. Most of the knowledge about the behavior of crocodiles comes from studies carried out in zoos and reserves, that is, on animals in captivity.
In some species, such as C. rhombifer, females may compete for mating opportunities if there are few males. The number of agonistic interactions in this species depends on the time of year and how many resources are available, such as nesting sites.
On the other hand, crocodile courtship behavior shows some variation among species, which may employ different forms of communication. Tactile interactions during pair formation are the most common among species. During courtship, the female will often raise her snout, and both the female and male will swim in circles in a slow chase.
Several studies have documented that the reproductive success of crocodiles in captivity depends on the level of interaction and the formation of dominance hierarchies. Because of this, animals should be put in the right places so they don't fight with each other and make it harder for them to mate.
Nest building and parental care
These reptiles show important parental care, including a selection of a suitable nesting site, nest construction, defense of the nesting territory, care of the eggs, and transport of the young. Likewise, in many species, mothers build burrows or shelters where they protect their young for several weeks.
In addition, it is known that these animals respond to the calls of the young, provide food, and move them from one place to another to avoid possible predators. The duration of parental care and the types of interaction provided by crocodiles to their young vary by species and even individual. In American alligators (A. mississippiensis), females may remain close to their young for up to 2 years, while in other species the care lasts only a few days.
The behavior of crocodiles in parental care is more related to females. However, cases have been reported in which both parents guard the nest or, if the mother dies or disappears, the father takes on the role of caretaker. Among some of the warning and alerting behaviors of crocodiles to intruders approaching their nests are the raising of the snout and the arching of the tail in the water.
The behavior of crocodiles as predatory animals consists mainly of the "sit and wait" strategy. In addition, these animals take advantage of the turbidity of the waters where they live to approach their potential prey undetected. Once a prey item is close enough, crocodiles quickly emerge from the water and capture it with their powerful jaws.
The saltwater crocodile (Crocodylus porosus) is a common predator of flatback turtles (Natator depressus) and olive ridley turtles (Lepidochelys olivacea). These animals stealthily stalk adult turtles near the shore, catching them as they finish nesting and return to the water. These animals are capable of following turtle tracks, which is considered an active hunting strategy. In some cases, crocodiles have been reported to come out of the water and dig turtle nests to consume their eggs.
Play behavior in crocodiles
Within crocodilian behavior, interactions of various types have been recorded, as well as attitudes that indicate some level of play. In species such as the broad-snouted caiman, the American alligator, and the saltwater crocodile, several types of play behaviors have been described, such as locomotor play, object play, and social play.
Locomotor play consists of intense and sustained movements, which are not related to a particular stimulus or reason. This is very peculiar since these animals are generally organisms with a low metabolic level that do not perform frequent sustained movements. In species such as the wide-mouthed caiman, juvenile individuals have been documented repeatedly sliding down tubes into pools of water, where they allow the current to slide them.
Playing with objects is a frequently observed behavior of crocodiles in nature reserves and zoos. In fact, in many places, keepers provide various play objects as part of habitat enrichment. In several species, such as American alligators and dwarf crocodiles, juveniles have been observed splashing water and repeatedly passing under dripping pipes or warm water showers.
Social play is the least common crocodilian behavior. However, in species such as the Nile crocodile, siblings have been observed fighting each other, indicating that this is a social play that enriches the development and abilities of these animals. In other species such as black caimans (Melanosuchus niger), juvenile individuals have been reported swimming in circles as if chasing each other, until they stop without any antagonistic outcome. This behavior is similar to that of adults in courtship season.
In adult Cuban crocodiles, what appears to be social play behavior has also been recorded, in which a female climbs on the back of a larger male, who repeatedly walks her around the water pond. Similar interactions have been observed in American alligator hatchlings, with the larger hatchlings walking the smaller ones.