johannesvanrooyen's Journal

Many lay people are under the impression that only the males of the southern rock agama (𝘈𝘨𝘢𝘮𝘢 𝘢𝘵𝘳𝘢) develop blue heads. The truth is that both the males and the females develop blue heads during the breeding season. But how do you then tell the males and females apart?
Bearing in mind that agamas can subdue their bright colours fairly quickly if they feel threatened and also that the specific characteristics are not absolute and can vary in their extent (sometimes being absent), the following can serve as a guide regarding the breeding colouration:

Males:
• Streak of blue or purple on the side near the belly behind the front legs (never seen in females).
• Reddish area in front of the back legs.
• Fairly uniform colouration on the back (ranging from brick red to bluish grey, sometimes almost
black), but with some lighter small spots and markings of a slightly different hue.
• Tail has some colour on the sides, usually yellow, but blue to bluish-green in some populations.

Females:
• Yellow "blush" on the rump near the back legs, but often extending further forward, sometimes over
the entire rump/torso area (males never have this yellow blush).
• Greyish background where the yellow blush don't reach.
• Rust-coloured markings on the body, contrasting strongly with the yellow or grey background (the
pattern of these markings correspond somewhat to those in males, but in males they are a similar
colour to the background and thus don't stand out much).
• Tail doesn’t have any colour.

There are also some other physical aspects that may differ between the sexes, although again it is not absolute:

Males:
• Generally larger in overall size.
• Jawline is often slightly broader.
• Tail is usually better developed, slightly flattened laterally but generally more bulky, sometimes with a
little crest of larger scales running down the middle.

Females:
• Generally smaller in overall size.
• Jawline is often slightly narrower.
• Tail is usually less well developed, rounder in cross-section, thinner and sometimes shorter. No crest.

Some breeding pairs:
https://www.inaturalist.org/observations/139408521
https://www.inaturalist.org/observations/67563782
https://www.inaturalist.org/observations/61860075
https://www.inaturalist.org/observations/191175877

Some males:
https://www.inaturalist.org/observations/190412280
https://www.inaturalist.org/observations/97986502
https://www.inaturalist.org/observations/61211970
https://www.inaturalist.org/observations/147831154
https://www.inaturalist.org/observations/184891185
https://www.inaturalist.org/observations/9228425
https://www.inaturalist.org/observations/143025666
https://www.inaturalist.org/observations/188709545
https://www.inaturalist.org/observations/101385982
https://www.inaturalist.org/observations/152609597
https://www.inaturalist.org/observations/133324336

Some females:
https://www.inaturalist.org/observations/143645814
https://www.inaturalist.org/observations/146468039
https://www.inaturalist.org/observations/173464815
https://www.inaturalist.org/observations/144963903
https://www.inaturalist.org/observations/145416431
https://www.inaturalist.org/observations/104416131
https://www.inaturalist.org/observations/37026553
https://www.inaturalist.org/observations/189509923

Some of the female characteristics of 𝘈𝘨𝘢𝘮𝘢 𝘢𝘵𝘳𝘢 can also be seen in females of some other species of 𝘈𝘨𝘢𝘮𝘢.

Note the diminutive tails and contrasting rust-coloured patches in these female eastern ground agamas (𝘈𝘨𝘢𝘮𝘢 𝘢𝘤𝘶𝘭𝘦𝘢𝘵𝘢 𝘥𝘪𝘴𝘵𝘢𝘯𝘵𝘪):
https://www.inaturalist.org/observations/190557824
https://www.inaturalist.org/observations/143724380
https://www.inaturalist.org/observations/142544804

The females of Anchieta’s agama (Agama anchietae) and Bibron’s agama (Agama bibronii) can be a close match to the females of 𝘈𝘨𝘢𝘮𝘢 𝘢𝘵𝘳𝘢:
https://www.inaturalist.org/observations/10819713
https://www.inaturalist.org/observations/185586248
https://www.inaturalist.org/observations/167774913
https://www.inaturalist.org/observations/159708354
https://www.inaturalist.org/observations/148341047
https://www.inaturalist.org/observations/145327257
https://www.inaturalist.org/observations/121469067