Geckos of Laguna de Apoyo, Nicaragua

The Asian House Gecko, Hemidactylus frenatus, has expanded rapidly since its successful introduction a few decades ago. It is displacing native species? Photo by Rachel Lauwerijssen.

Geckos are special animals. They climb on walls and ceilings, inhabiting all houses in Nicaragua, but they are wild animals, not pets. And generally, they are tolerated and even enjoyed by us bipeds. Their chirping, hunting antics, and those eggs found in boxes, shoes, and other enclosures are always innocuous and most often charming. And they are in the forests, too. It's common to see pictures of geckos in trip reports by tourists!

Nonetheless, there is more to the story than that Nicaragua has geckos. In fact, there are several species here; in Laguna de Apoyo Nature Reserve, three species are present; two species are native, and one was recently introduced to Nicaragua. Two students from Holland, Rachel Lauwerijssen and Simone Blomenkamp, are studying these animals to determine what impacts, if any, the introduced species may produce on the native populations. Simone started her study a month ago, and Rachel has just finished in Spanish training, at Laguna de Apoyo Spanish School, and is now at full speed in the study, too.

One of the species native to the area is the yellow-headed gecko, Gonatodes albogularis. The head of the male of the subspecies found in Nicaragua is more brick red than yellow, however. Although all geckos are collectively called perrozompopo (ant-dog in Spanish!) locally, some people recognize that this form exists, as opposed to the more neutral form (see above). It is generally more reclusive than the exotic species.

This mail Yellow-headed Gecko is undergoing molt. 

The female yellow-headed gecko can be confused with other geckos without a closer look, given their neutral colors. Most commonly seen by Nicaraguans is the Asian house gecko (Hemidactylus frenatus), which was introduced into Nicaragua a few decades ago. This picture was taken on the wall of Estacion Biologica. It is not clear just how the Asian house gecko first arrived in Nicaragua, although some blame the Panamians, others blame the Cubans coming from Angola in the 1980's! At any rate, it is prolific, and highly reproductive, as the photos in a previous blog entry attest.
Simone and Rachel are gathering data on the abundance of each species in a variety of habitats in Laguna de Apoyo Nature Reserve, to evaluate whether the introduced species has any impacts on the species native to here. They have study locations both in trees and in structures such as houses.

Simone Blomenkamp taking notes during field work in Laguna de Apoyo Nature Reserve. Photo by Witold Lapinski.

Simone Blomenkamp photographing a gecko in Laguna de Apoyo Nature Reserve. Photo by Witold Lapinski.

Neutral colors on the female yellow-headed gecko (Gonatodes albogularis) combine with a cryptic pattern to aid in predator avoidance. Photo by Simone Blomenkamp.

A third gecko species is found in Laguna de Apoyo Nature Reserve, the yellow-belly gecko (Phyllodactylus tuberculosus). This species is much less abundant than the other two in all the habitats we have evaluated so far. In fact, about two weeks of intense study had passed before we sighted the first one.

Yellow-bellied gecko, Phyllodactylus tuberculosus, at Estacion Biologica, Laguna de Apoyo Nature Reserve. Photo by Simone Blomenkamp.

Nature photographers enjoy watching the geckos and other lizards of Laguna de Apoyo Nature Reserve, because they often give great photography opportunities.

The sticky pads on Phyllodactylus tuberculosus feet in ventral view. Photo by Witold Lapinski.

Finding the yellow-bellied gecko actually was not easy. Over one-hundred geckos had been sighted before the first one had appeared. The sticky foot pads, seen above, are distinctive for this species. The foot pad morphology will dictate the appropriate habitat for the species, and given that the pads are not as extensive as in the introduced species, we ask whether there are problems with aquiring appropriate habitat. We are focussing on how Hemidactylus frenatus may compete with this species for resources.

Simone Blomenkamp photographs the first yellow-bellied gecko captured during the study in Laguna de Apoyo Nature Reserve, as Jeffrey McCrary holds the gecko. Photo by Rachel Lauwerijssen.

The geckos captured in some sites are marked for a quantitative population study. Below, the yellow-bellied gecko with markings has been released near its capture site. Each marked individual has a unique pattern, allowing us to identify the individual when observing it.

Yellow-bellied gecko, Phyllodactylus tuberculosus, marked for a population estimate study. Photo by Simone Blomenkamp.

Rachel Lauwerijssen with a gecko in hand, during field work in Laguna de Apoyo. Rachel has just finished his study at Laguna de Apoyo Spanish Language School, and now he will devote his efforts to study of the geckos. Photo by Witold Lapinski.

The Asian house gecko has often been blamed for the demise of native gecko species in other places, but in Nicaragua, no one has bothered to analyze the potential impacts provoked by the introduction of this species. We intend to generate specific information on habitats of each species, overlaps, fertility, competition, and potentially, predation for each species.

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