Common Chameleon Chamaeleo Chamaeleon Research Articles

The common chameleon Chamaeleo chamaeleon in southern Italy: evidence for allochthony of populations in Apulia and Calabria (Reptilia: Squamata: Chamaeleonidae)

The common chameleon Chamaeleo chamaeleon is present in many Mediterranean countries. Its occurrence in Italy is historically reported for Sicily, where it appears to be no longer present. While many contemporary findings across the Italian Penisula refer to single observations, likely due to introduced or released animals, the species turned out to be established in two southern regions (Apulia and Calabria) with acclimatised populations. To investigate their provenance, we analysed tissue samples of individuals from these localities. A fragment of the mitochondrial 16S rRNA gene was amplified and compared with sequences available in Genbank. Our results showed that individuals from Calabria share haplotypes with those from Tunisia (N. Africa), while those from Apulia are coincident to samples from Israel. This suggests that individuals were most likely introduced in Italy.

Camouflage and escape decisions in the common chameleon Chamaeleo chamaeleon

In species with reduced locomotory abilities, camouflage seems to be far more important than other behavioural tactics (e.g. running) to elude predatory attacks. In this study, we examined the effects of camouflage on escape decisions in the common chameleon Chamaeleo chamaeleon. The effectiveness of camouflage was assessed by the ability of humans to detect different sized chameleons placed on different backgrounds (vegetation of high and low density, defined here as open and dense bushes), both in the field and in photographs. Escape behaviour was analysed by simulating a predator attack (in our case, approach by a human). As expected, the probability of detection by a potential predator was size- and background dependent. In the field, detection time (but not distance) was significantly higher for chameleons of a given size perched on dense (Myoporum) than open (Retama) bushes. When using photographs, the probability of detection was higher for large (adult) chameleons perched on open (Retama or Nerium) bushes and lower for hatchlings perched on dense (Myoporum or Cupressus) bushes. Conspicuousness greatly influenced the escape tactics of individuals. Chameleons perched on more protected Myoporum allowed closest approach distances than those perched on less protectedRetama . In general, antipredatory responses (defined here as «first movement», «fleeing», «mouth opening» or «free falling») occurred significantly earlier in the trial sequence in chameleons perched on clear Retama than those perched in Myoporum. Two antipredatory responses were size-dependent: juveniles and adults exhibited «mouth opening» more frequently than hatchlings whereas «free falling» was more frequently recorded for hatchlings. Our results suggest that size and vegetation greatly influence the risk of detection by predators and this variation influences an individual's decision about when and how to escape.

Camouflage and escape decisions in the common chameleon Chamaeleo chamaeleon

In species with reduced locomotory abilities, camouflage seems to be far more important than other behavioural tactics (e.g. running) to elude predatory attacks. In this study, we examined the effects of camouflage on escape decisions in the common chameleon Chamaeleo chamaeleon. The effectiveness of camouflage was assessed by the ability of humans to detect different sized chameleons placed on different backgrounds (vegetation of high and low density, defined here as open and dense bushes), both in the field and in photographs. Escape behaviour was analysed by simulating a predator attack (in our case, approach by a human). As expected, the probability of detection by a potential predator was size- and background dependent. In the field, detection time (but not distance) was significantly higher for chameleons of a given size perched on dense (Myoporum) than open (Retama) bushes. When using photographs, the probability of detection was higher for large (adult) chameleons perched on open (Retama or Nerium) bushes and lower for hatchlings perched on dense (Myoporum or Cupressus) bushes. Conspicuousness greatly influenced the escape tactics of individuals. Chameleons perched on more protected Myoporum allowed closest approach distances than those perched on less protectedRetama . In general, antipredatory responses (defined here as «first movement», «fleeing», «mouth opening» or «free falling») occurred significantly earlier in the trial sequence in chameleons perched on clear Retama than those perched in Myoporum. Two antipredatory responses were size-dependent: juveniles and adults exhibited «mouth opening» more frequently than hatchlings whereas «free falling» was more frequently recorded for hatchlings. Our results suggest that size and vegetation greatly influence the risk of detection by predators and this variation influences an individual's decision about when and how to escape.

The influence of female size on the extent and intensity of mate guarding by males in Chamaeleo chamaeleon

AbstractIn ectotherms, the size of the female correlates with fecundity and thus, males prefer large more fecund females as potential mates in some species. The idea that the extent and intensity of mate guarding are also size‐related was tested in the common chameleon Chamaeleo chamaeleon. Mate guarding was studied in 43 radio‐tagged females during 3 years in a population in southern Spain. The extent and intensity of male guarding of their mates varied greatly. On average, the guarding started on 20 August and ended on 2 September (mean duration = 12.6 days, range 2–44 days, n= 35; six females were not guarded). Guarding continued for some days after mating (range = 0‐13 days, n= 16). Guarding intensity (mean = 65.8% of net observation time with a guarding mate, range = 23–90, n= 27) and number of guarding males (mean = 1.8, range = 1–7) also varied greatly. The extent and intensity of mate guarding was strongly influenced by female size and the guarding period after mating: large females were guarded early in the season, for longer periods, and more intensively than small ones. Large females were also guarded for longer periods after mating. The overall variation in the guarding period was due to the duration of guarding before mating which was longer for large females. To my knowledge, this is the first time that prolonged mate guarding of larger females has been reported.

Models painted with female-like colors elicited courtship by male common chameleons: Evidence for a courtship releaser

Female common chameleonChamaeleo chamaeleon shows shifts in body colorations during the mating season associated with their sexual stage. The hypothesis that female colorations are used in the inter-sexual communication was tested in the field by using plastic models painted with female-like colors. Three female colorations (Neutral, Receptive and Gravid) and two artificial colorations (White and White plus black spots) as control were used. Twenty models (5 colorations × 4 replicas) were simultaneously located in the field (n=25 experiments), and the reaction by males was scored from 0 (no reaction) to 4 (copulation attempt). A male was observed nearby a model in 59 out of 500 displays. A total of 23 males (38.9%) actively reacted to the model. The response significantly differed among color types, and receptive-like models obtained the strongest response by males. In five cases, males attempted to copulate with the model. The response to receptive coloration by males agrees with previous field studies and suggests that yellow spots with a green background is a courtship releaser.