Lizards, often seen as insectivores, can exhibit a complex behavior: consuming other lizards. This phenomenon, known as cannibalism, is present across various species.
The Reality of Lizard Cannibalism
Consuming other lizards, including their own species, is a recognized behavior among many lizard groups. This predation is a documented part of the ecological interactions of numerous carnivorous or omnivorous lizard species. It occurs across different habitats and continents, indicating its widespread nature in the reptile world. Smaller individuals are typically the prey in such events, serving as opportunistic meals for larger conspecifics.
Factors Driving This Behavior
Several interconnected factors contribute to the occurrence of cannibalism in lizards. Resource scarcity frequently plays a role, as limited food availability can compel lizards to prey on smaller or weaker individuals of their own kind to survive.
Territoriality also drives this behavior, particularly among dominant lizards. They may eliminate competitors within their territory, sometimes consuming them, which serves to reduce competition for resources and mates.
Size disparity is another significant factor, with larger lizards preying on much smaller ones, often juveniles. This is a straightforward consequence of opportunistic feeding. Adult males, especially, are observed to consume juveniles due to these size differences.
High population density can increase the likelihood of encounters between lizards. In crowded conditions, competition for food and space intensifies, leading to more frequent intraspecific aggression. This can result in cannibalism as a means of population regulation and resource acquisition.
Opportunistic predation, often linked to a generalist diet, also underpins cannibalistic tendencies. Lizards that are not specialized feeders may consume anything they can overpower, including their own kind if encountered unexpectedly. This flexibility in diet allows them to exploit available food sources, even if it means preying on conspecifics.
Common Examples of Lizards That Eat Lizards
Komodo dragons, the largest living lizards, are well-known for their cannibalistic tendencies, particularly preying on their young. Juvenile Komodo dragons often climb trees to avoid being eaten by larger, adult dragons, as young individuals can comprise a portion of the adult diet. This behavior helps sustain the large size of adults in environments where medium-sized prey might be less common.
Various skink species also exhibit cannibalism, which can include consuming smaller individuals or even eggs. For example, some mother skinks have been observed to eat their own eggs, a behavior that can be linked to survival instincts in response to high predation pressure from snakes. Southeastern five-lined skinks occasionally engage in cannibalism, especially when circumstances necessitate it.
Geckos, a diverse group of lizards, also show instances of cannibalism. Studies have documented that 34 out of 64 reviewed gecko species engage in cannibalism. The common house gecko, for example, is an opportunistic feeder known to exhibit cannibalism, sometimes consuming juveniles or eggs. Leopard geckos have also shown cannibalistic behavior, particularly among younger individuals in captive settings.
Wall lizards, such as the Aegean wall lizard and common wall lizard, have also been observed in cannibalistic acts. Researchers documented an instance of an Aegean wall lizard consuming another, suggesting it can be an adaptive strategy, especially in dense populations. Large male common wall lizards, being opportunistic, have been noted to eat smaller individuals of their own species.