The Tropical or Amazon thornytail iguana – Uracentron flaviceps

Jun 02, 2019 Interesting Creatures in Guyana, News

Uracentron flaviceps, the tropical thornytail iguana or Amazon thornytail iguana is an elusive species of medium sized arboreal lizard found in the tropical lowlands of the Amazon Rainforest.

Uracentron flaviceps

The species has been noted in the lowlands of eastern Ecuador, eastern Peru, northwestern Brazil, and in the extreme southern regions of Colombia, they may be found in Bolivia as well.
Tropical thornytail iguanas are only found in the Amazon rainforest, and within the rainforest are generally found in lowland tropical rainforest; usually areas with lagoons, rivers, streams, and palm swamps. They are an arboreal species, spending the majority of their life in high treetops. They prefer trees with high horizontal branches that allow for basking in the sun during the morning hours, and are almost only found in trees that contain hollow areas accessible through entrances in the tree branches and trunks. No specific species of tree has been found to be favoured by the lizards, it would appear the tree structure, rather than the tree species, is what the lizards prefer.
Males can reach up to 13 cm (5.1 in) in snout–vent length, while the smaller females only reach 9.5 cm (3.7 in). They have a large, flat tail covered in scales that end in a point; the function of these scales is currently unclear. The body is brown in colour, speckled with yellow or gold spots. Some specimens found in Ecuador and Peru were noted as having a black collar around their necks. This collar is bordered by narrow light coloured edges.
Sexually mature males differ from females, and juveniles in appearance, and it has been hypothesized that this may be the result of sexual selection. The males display longer and deeper heads, as well as longer limbs when compared to females.
Females are also generally a little bit shorter in length than males. Sexually mature males also display different coloration than females or juveniles. Sexually mature males have an orange head and black body, in contrast to the much more subdued colouring and yellow heads of females, juveniles, and not sexually mature males.
Males that reach sexual maturity also have enlarged testes when compared to those of males that have not reached sexual maturity.
Tropical thorny tail iguanas are considered a sit and wait, or ambush predator. They are considered ant specialists, and various species of ants that wander the limbs and trunks of the trees inhabited by tropical thorny tail iguanas make up a large percentage of their diet.
Larger lizards will eat slightly larger prey as well such as stingless bees, hemipterans (also known as true bugs), and beetles. Interestingly alates, which have been established as a prey item of the tropical thorny tail iguana, are not usually present on the limbs and trunks of trees. It is possible that the lizards will break into the alate nests in the trees, or that they may only eat the species when releases occur. If they do break into the nests it is a highly unusual behaviour, as rarely will an ambush predator actively seek its prey. In studies investigating the eating behaviours of this species there was no difference in the amount of prey consumed between male and female specimens. This indicates that resource partitioning is not the reason for the difference in head size between and male and female tropical thornytail iguanas.
The species is diurnal, active during the daytime. The level of activity exhibited is at least partially dependent on the presence of sunlight. Individuals emerge once the sun comes out, and will remain active unless cloud cover reduces sunlight.
The approximate times of activity are from 8:30am until 5:00pm and males appear to emerge from holes in trees earlier than females and juveniles. Upon emerging from the tree lizards will bask in the sun to raise their body temperature until activity body temperatures are reached. When approached by humans or startled the lizards will either run into their holes to hide or run out on limbs of the tree to avoid whatever startled them.
The tropical thorny tail iguana has a resource defence polygyny social structure in which there is one sexually mature male to a group of females and juveniles. Resource defence polygyny means that the females do not necessarily live in extremely close quarters but the resources the females need are clustered together. This creates a group of females, and the resources they need, that a male can claim as his territory. This allows the male to be polygynous with minimal effort defending a resource-based territory.
The breeding season for this species appears to be extended, based on observations of juveniles of different sizes in a single tree.
During the breeding season, males become more territorial and will engage in displays of head bobbing and body movements to warn away other males who may try to infringe on their territory. These displays are also used to attract a potential mate.
Like most reptiles tropical thorny tail iguanas are oviparous and lay clutches of eggs. For this species clutches are usually two eggs per female, and clutches smaller than two eggs are very rare. The eggs are laid in nests deep within the holes of trees inhabited by a group of tropical thorny tail iguanas.
The conservation status of the tropical thorny tail iguana is currently uncertain, but it is thought that the loss of the species’ preferred habitat to deforestation is the main threat to the species. [Source: Wikipedia]