They may be tiny but they are plentiful, and ants make up a significant part of the diet of southern tree agamas. For agamas, catching ants seems relatively easy: find an ant pathway and waylay the passing ants. Simply pick them out one at a time using the tongue to scoop and swallow.
Southern tree agamas (Acanthocercus atricollis) are endlessly fascinating to watch and they are a welcome presence in the garden. Breeding males develop bright blue heads in the breeding season and hence they are also known as blue-headed lizards.
A male southern tree agama showing his full breeding colours offset nicely by the flowers of the wild pomegranate (Burchellia bubaline)
Even when displaying his bright breeding colours the male is able to change his colours to the regular camouflage colours of the female, for example when he is under threat. Although more subtle, the female’s markings are also beautiful.
This individual is showing more muted colouration as it waits to catch and eat ants that are passing by
Not all lizards can eat ants – the formic acid is not palatable to all species. Ants form a significant part of the diet of southern tree agamas. In terms of numbers of prey items, ants are in the vast majority in the diet, but as ants are relatively tiny they do not form the bulk of the diet by volume.
Although numerically ants followed by beetles are the major prey items in the diet of southern tree agamas, by volume members of the grasshopper family predominate, followed by beetles and then by ants. It takes a lot of ants to add up to the mass of even one large grasshopper!
There is something rather endearing about this baby southern tree agama. For juvenile agamas ants form a higher proportion of their diet than for adults who are more proficient hunters and are better able to cope with larger prey items
In addition to eating ants, beetles, bugs, flies and members of the grasshopper family, southern tree agamas are also known to consume caterpillars, millipedes, slugs and snails and as well as plant material such as seeds and buds.
For the most part southern tree agamas are ambush hunters, positioning themselves so as to improve their chances of being in the right place at the right time to catch passing prey. However, they can opportunistically pursue prey in order to catch it if needs be, as evidenced by the fact that wasps and bees form a regular part of their diet as do members of the dragonfly family.
Even the baby agama is capable of showing a predatory demeanour and looks rather less anthropomorphically ‘cute’ in this photo than in the one above
Southern tree agamas are thought to be fairly social and they may live in loose coalitions or family groupings with a breeding male dominating the territory. However, during the breeding season rivalry between males for territory and breeding rights can turn into surprisingly savage battles, as I once witnessed and was able to catch on video as can be seen here.
In November last year, while having breakfast out on our front deck I noticed a southern tree agama breakfasting on ants in a nearby powder-puff tree (Barringtonia racemosa). The ants were attracted to the flowers of this tree and in turn the regular procession of ants to and fro attracted the attention of the agama.
Setting my breakfast aside I got my camera and took a video of the agama eating ants. It simply waited for ants to approach and picked them off one by one using its tongue, and swallowed each ant immediately.
While watching and filming I also saw a gecko approaching along a tree branch and then taking evasive action when it noticed the agama – some of this behaviour can be seen in the video. Numerous birds provide a soundtrack; most notable is the calling of a pair of black-headed orioles.
Alexander, Graham; and Johan Marais. 2007. A Guide to the Reptiles of Southern Africa. Cape Town: Struik Nature; Reaney, Leeann T; and Martin J Whiting. 2006. Life on a limb: Ecology of the tree agama (Acanthocercus a. atricollis) in southern Africa. Journal of Zoology. 28 February. https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1017/S0952836902001048; Tan, Wei Cheng; Anthony Herrell, and John Measey. 2020. Dietery observations of four Southern African agamid lizards (Agamidae), Herpetological Conservation and Biology, 15(1). http://www.herpconbio.org/volumes.html
Posted by Carol