Author: Matthijs van den Burg

New community science reports show that the Peters’s Rock Agama (Agama picticauda) is spreading from Florida and has reached the Bahamas and the British Virgin Islands, undoubtedly carried as stowaways on outbound vessels. A group of Caribbean-based biologists and conservationists are expressing their deep concern because this region is a biodiversity hotpot with thousands of unique, endemic species, over 1,500 of which are already at high risk of extinction.

In their letter to the journal Animal Conservation, the authors identify nearly 50 native reptile species (among which many species of Anolis) that could be impacted if the agama becomes established across the Eastern Caribbean. Given that it is known to capture prey up to at least 5 cm snout-vent length, many species are at risk of being eaten by the agamas; even large native lizards are likely to experience competition and displacement given the agama’s aggressive behaviours.

The authors advise scientists, conservationists, policy makers, veterinarians and border control agencies to be on high alert for incursions by Peters’s Rock Agamas and other non-native reptiles. They further urge the transport sector – especially those operating out of Florida – to be on the lookout for the agama and to take swift measures to remove them.

The letter has been published in Animal Conservation: M.P. van den Burg et al.: The threat of Peters’s Rock Agama (Agama picticauda) to reptile diversity across the Lesser Antilles. Animal Conservation 2023, 12889. https://doi.org/10.1111/acv.12889

Anolis cristatellus predating on Eleutherodactylus martinicensis; photo taken by Jeanelle Brisbane

In the (sub)tropics of the Western Hemisphere, it is not uncommon to come across sleeping anoles while strolling around at night in (partially) vegetated areas; they are after all considered diurnal. It was therefore quite a shock when active anoles appeared in the beam of our headlights during the nights of 18 January and 16 April 2019 on the Commonwealth of Dominica. On the first night, we observed how a juvenile Anolis cristatellus (non-native) jumped from one grass style to the next and successfully caught a fly; on the second night, the adult A. cristatellus had a still alive and resisting, frog (Eleutherodactylus martinicensis) in its mouth (see photo).

An increasing number of anole species are being found to utilize artificial light sources after sunset, and thereby extend their activity period, allowing increased growth and fecundity. What made our encounter especially unsuspected was the absence of artificial light in the area we were surveying for the removal of newly arrived alien species. Instead, these nights (waxing gibbous with 91.7-92.9% visibility) were close to the full moon, and without cloud cover. Our observations were at 19:59 and 20:40h, almost 2 hours after the end of astronomical twilight; it was night.

The area of our observations consists of several abandoned plots nearby the harbor, overgrown with grasses, vines, and bushes. The edges of this open area are partially made up of a single line of trees, shorter than 7 m in height.

Our observations indicate a potential understudied part of anole ecology, though more observations are needed to understand the occurrence of this behavior, both within and among species. However, ex-situ, some authors have already demonstrated that anoles show activity under moonlight conditions, which appeared more evident for shade-adapted species.

In our paper just published in Neotropical Biodiversity, we discuss several to-be-tested hypotheses and address how our observations could shed new light on anole predation by nocturnal predators, like owls and bats. Beyond anoles, observations of nocturnal activity by diurnal reptiles have been reported on some occasions. The observations of this behavior in Anolis are of special importance given the large body of literature and understanding of these model species; allowing the scientific community to test hypotheses and move beyond observational reports.

Excitingly, since the publication of our work we have been in contact with enthusiast readers of which one indicated to have observed moonlight-facilitated activity as well but did not write that up, yet.