Chamaeleo chamaeleon

[Luena Soraya]

Hello, I'm doing a project about the Chamaeleo Chamaeleon distribution but I am having trouble with some things. Since chameleons are hard to find, my project counts with the help of local communities to stay alert and take pictures with the location to send to us so we can gather all the sightings and work with the data for that project. So I'll have to identify chameleons through pictures which is rather difficult sometimes. And that is where my troubles surfaces.

Firstly, distinguishing juveniles from adults. To find info about how to distinguish them in other species is easy but since this species isn't really a domestic animal, I can't find much info on how to distinguish them. Some are easy to know but I want the data to be as correct as possible. (have attached pictures as examples)

Secondly, if there is the possibility of knowing if it's a male or a female through pictures.

Third and last, I know the change of colors is very related to their communication and physiological behavior (if they are going to put eggs, stress, ...). How can I read into the coloration? Does anyone know it or can show me scientific papers where I can look into it?

If anyone could help me, I would be very thankful!

 

[Beman]

@kinyonga do you know of any papers on these guys?

 

[Chris Anderson]

Distinguishing juveniles from adults is difficult from photographs. The best method for this species would be based on body length (Snout-Vent Length), but this is obviously difficult from photographs. After viewing enough images of this species, you could probably start to gauge juvenile vs adult based on the development of some of the cranial features (size of the crest, etc.), but again this is quite challenging. In some of Cuadrado et al.'s various studies on this species they determined age based on body size.

For sexing, you would need to examine the tail base for the hemipenal bulge. This is easier in some images than others as it needs to be at the right angle, in good focus and unobstructed. Other sexing methods for this species are unreliable as they are size monomorphic and secondary sexual characters are less pronounced than other species.

I would recommend reading many of Cuadrado's previous studies on this species for information on coloration and what it means. In particular he has various studies on mating behavior and color as sexual reproductive status signals. Here are a few articles you should probably check out:

Bons J, Bons N. 1960. Notes sur la reproduction et le développement de Chamaeleo chamaeleon (L.). Bulletin de la Société des Sciences Naturelles et Physiques du Maroc 40: 323-335.
Cuadrado M. 1998. The influence of female size on the extent and intensity of mate guarding by males in Chamaeleo chamaeleon. Journal of Zoology 246: 351-358.
Cuadrado M. 1998. Models painted with female-like colors elicited courtship by male common chameleons: evidence for a courtship releaser. Journal of Ethology 16: 73-79.
Cuadrado M. 1998. The use of yellow spot colors as a sexual receptivity signal in females of Chamaeleo chamaeleon. Herpetologica 54: 395-402.
Cuadrado M. 1999. Mating asynchrony favors no assortative mating by size and serial-type polygyny in common chameleons, Chamaeleo chamaeleon. Herpetologica 55: 523-530.
Cuadrado M. 2000. Body colors indicate the reproductive status of female common chameleons: experimental evidence for the intersex communication function. Ethology 106: 79-91.
Cuadrado M. 2000. Influence of female's sexual stage and number of available males on the intensity of guarding behavior by male common chameleons: a test of different predictions. Herpetologica 56: 387-393.
Cuadrado M. 2001. Mate guarding and social mating system in male common chameleons (Chamaeleo chamaeleon). Journal of Zoology 255: 425-435.
Cuadrado M, Loman J. 1999. The effects of age and size on reproductive timing in female Chamaeleo chamaeleon. Journal of Herpetology 33: 6-11.
Cuadrado M, Martín J, López P. 2001. Camouflage and escape decisions in the common chameleon Chamaeleo chamaleon. Biological Journal of the Linnean Society 72: 547-554.
Fernández F. 1988. La adquisición de la madurez sexual en el camaleón común Chamaeleo chamaeleon. Doñana Acta Vertebrata 16: 5-13.
Fernández F. 1994. Biología y comportamiento del camaleón común Chamaeleo chamaeleon: Rota: Fundación Alcalde Zoilo Ruíz-Mateos.

There are of course many other papers on this species, but these are probably particularly relevant.

Chris

 

[kinyonga]

Suggestions...if you are having people take photos and you want to determine whether the chameleon is a jeuvenile or adult, have the person put something in the photo that will give an indication of size.

Have them also take a photo from the side so we can see the base of the chameleon's tail and the casque/helmet of the head. This will help determine the sex. Males have a hemipene bulge and the casque protrudes at the back more than in the female

I'm going to collect more information for you but it will take me a bit of time...so I'll be back later.

I actually kept some chamaeleo chamaeleons in the 90's. I also hatched the eggs and raised the babies into adulthood.
This might help a little in the meantime...
These are my chameleons...the male and female shows a bit how the casque differed between the sexes...
http://www.adcham.com/html/taxonomy/species/cchamaeleon.html

This one gives you quite a bit of information on color,etc....
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0159032

 

[Luena Soraya]

Distinguishing juveniles from adults is difficult from photographs. The best method for this species would be based on body length (Snout-Vent Length), but this is obviously difficult from photographs. After viewing enough images of this species, you could probably start to gauge juvenile vs adult based on the development of some of the cranial features (size of the crest, etc.), but again this is quite challenging. In some of Cuadrado et al.'s various studies on this species they determined age based on body size.

For sexing, you would need to examine the tail base for the hemipenal bulge. This is easier in some images than others as it needs to be at the right angle, in good focus and unobstructed. Other sexing methods for this species are unreliable as they are size monomorphic and secondary sexual characters are less pronounced than other species.

I would recommend reading many of Cuadrado's previous studies on this species for information on coloration and what it means. In particular he has various studies on mating behavior and color as sexual reproductive status signals. Here are a few articles you should probably check out:

Bons J, Bons N. 1960. Notes sur la reproduction et le développement de Chamaeleo chamaeleon (L.). Bulletin de la Société des Sciences Naturelles et Physiques du Maroc 40: 323-335.
Cuadrado M. 1998. The influence of female size on the extent and intensity of mate guarding by males in Chamaeleo chamaeleon. Journal of Zoology 246: 351-358.
Cuadrado M. 1998. Models painted with female-like colors elicited courtship by male common chameleons: evidence for a courtship releaser. Journal of Ethology 16: 73-79.
Cuadrado M. 1998. The use of yellow spot colors as a sexual receptivity signal in females of Chamaeleo chamaeleon. Herpetologica 54: 395-402.
Cuadrado M. 1999. Mating asynchrony favors no assortative mating by size and serial-type polygyny in common chameleons, Chamaeleo chamaeleon. Herpetologica 55: 523-530.
Cuadrado M. 2000. Body colors indicate the reproductive status of female common chameleons: experimental evidence for the intersex communication function. Ethology 106: 79-91.
Cuadrado M. 2000. Influence of female's sexual stage and number of available males on the intensity of guarding behavior by male common chameleons: a test of different predictions. Herpetologica 56: 387-393.
Cuadrado M. 2001. Mate guarding and social mating system in male common chameleons (Chamaeleo chamaeleon). Journal of Zoology 255: 425-435.
Cuadrado M, Loman J. 1999. The effects of age and size on reproductive timing in female Chamaeleo chamaeleon. Journal of Herpetology 33: 6-11.
Cuadrado M, Martín J, López P. 2001. Camouflage and escape decisions in the common chameleon Chamaeleo chamaleon. Biological Journal of the Linnean Society 72: 547-554.
Fernández F. 1988. La adquisición de la madurez sexual en el camaleón común Chamaeleo chamaeleon. Doñana Acta Vertebrata 16: 5-13.
Fernández F. 1994. Biología y comportamiento del camaleón común Chamaeleo chamaeleon: Rota: Fundación Alcalde Zoilo Ruíz-Mateos.

There are of course many other papers on this species, but these are probably particularly relevant.

Chris

wow, thank you so much. And I really appreciate all those references. Now I have a lot to read on summer vacation

 

[Luena Soraya]

Suggestions...if you are having people take photos and you want to determine whether the chameleon is a jeuvenile or adult, have the person put something in the photo that will give an indication of size.

Have them also take a photo from the side so we can see the base of the chameleon's tail and the casque/helmet of the head. This will help determine the sex. Males have a hemipene bulge and the casque protrudes at the back more than in the female

I'm going to collect more information for you but it will take me a bit of time...so I'll be back later.

I actually kept some chamaeleo chamaeleons in the 90's. I also hatched the eggs and raised the babies into adulthood.
This might help a little in the meantime...
These are my chameleons...the male and female shows a bit how the casque differed between the sexes...
http://www.adcham.com/html/taxonomy/species/cchamaeleon.html

This one gives you quite a bit of information on color,etc....
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0159032

Thank you so much for your help! And the photos do help a lot. I'll try to talk with people so they can try taking better pictures but it's already great when they send one at least For the project I'm also working outside trying to talk with people about our project and how they can help but most just dismiss it as usual when it comes to nature awareness actions

 

[kinyonga]

Why are you doing this study? School thesis? Or??

 

[Chris Anderson]

Its worth noting that the differences in casque size increase with body size, but there is a large range of moderate to small adult body sizes where these casque dimension differences are much less pronounced and even overlap. I performed field work on Chamaeleo chamaeleon in 2017 in Spain where we measured cranial dimensions and bite forces of 145 individuals and found that large adult males have disproportionately larger heads than large adult females, but that this difference diminishes among smaller adults. So, I do not think this would be a broadly reliable indicator of sex for this species, particularly from photos.

Chris

 

[kinyonga]

https://www.chameleonforums.com/threads/sexing-common-chameleon.159391/

 

[kinyonga]

@Chris Anderson said..."large adult males have disproportionately larger heads than large adult females"...this is true...but I had no problems telling the subadult males and females apart either...but I only sexed a few dozen of them.

 

[Chris Anderson]

@Chris Anderson said..."large adult males have disproportionately larger heads than large adult females"...this is true...but I had no problems telling the subadult males and females apart either...but I only sexed a few dozen of them.

Unfortunately, when we graphed the measurements of those 145 specimens, on average these differences held true, but there is a considerable amount of overlap in the sexes in their cranial dimensions at all but the largest of specimens (>130mm SVL), and that overlap exceeds 50% of individuals <120mm SVL. Given that data, and particularly since sexing in this case would be base on photos, which are also subject to perspective issues that can impact how large or small certain features may appear, I think hemipenal bulge is the only reliable way to sex them in this case.

Chris

 

[kinyonga]

https://www.animal.photos/reptamph/cham-med.htm

 

[Luena Soraya]

Why are you doing this study? School thesis? Or??

I'm still doing graduation in biology but as last year we have a choice do do a one semester project (some kind of a way to train for investigation and master/master thesis). So I decided to do it in a local organization, that is trying to create a place for chameleon rehabilitation and study, in specific related to distribution since the data we have about their distribution in our zone is old and far from updated. For now I'm volunteering in the organization and get data to do the project and trying to figure out with what I have what I can do or not