Behavior

Most geckos are nocturnal and emerge from hiding in the early evening to forage and seek mates. Because they gain most of their heat via conduction from warm surfaces, their body temperatures drop as the night progresses, and activity may be limited to just a few hours at cooler times of the year. Diurnal geckos may have one or two peaks of activity during the day, often in the late morning and again in the mid- to late afternoon. Tropical species are active year-round, but in the north and south of the family's distribution, geckos remain inactive, deep in burrows or crevices, during cold periods. They rarely cease all activity, however, and can emerge to take advantage of warmer nights.

Many geckos are relatively solitary, though Bibron's gecko (Pachydactylus bibronii) and some other species can reach very high densities and may share retreat sites. These geckos have

A parachute or flying gecko (Ptychozoon sp.) in the East Indies. (Photo by Animals Animals ┬ęStephen Dalton. Reproduced by permission.)
A Tokay gecko (Gekko gecko) in defensive posture. (Photo by Kim Taylor. Bruce Coleman, Inc. Reproduced by permission.)

reduced levels of aggression toward one another, but there is little evidence of a complex social structure. In the Indian golden gecko (Calodactylodes aureus), only the largest male in an area is brightly colored. If he is removed, the next largest male assumes this color and associated dominant status.

Many geckos, especially males, actively defend important resources, such as retreat sites and feeding areas. These geckos stave off rivals of their own and other species by vocalizing, using complex patterns of clicks and chirps. Geckos also use vocalizations, in combination with bites and defecation, to deter predators. Many geckos have cryptic coloration or outline-concealing skin folds and flaps to avoid detection, and a few, such as the Namib day gecko (Rhoptropus afer), can outrun most predators. Tail autotomy, the ability to shed or drop the tail, is common among geckos. Threatened geckos lure predators to attack the tail, which continues to wriggle after it is shed, distracting the predator and allowing the animal to escape. The loss of the tail usually carries with it a significant energetic cost, but in the marbled gecko (Christinus marmoratus), tail loss has the immediate benefit of increased running speed. Certain geckos, mostly island species, also can shed large portions of their body skin if they are grasped by predators, and they can regrow skin over the large wounds. Members of two genera of diplodactyline geckos (Strophurus and Eurydactylodes) can ooze or squirt a sticky fluid from the tail that can entangle the mouth parts of such predators as spiders.

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