Lizards of Laguna de Apoyo I: Conservation Science Interns at Work

The Central American Banded Gecko is very attractive, but its intricate pattern hides it well among leaf litter during the dry season. Photo by Laura Ruysseveldt.  

The tropical dry forest habitat of Laguna de Apoyo Nature Reserve dictates the kinds of animals found here. Both plants and animals must tolerate long months without rain, and in many areas, steeply inclined soils stripped of nutrients. Several species of lizards adapt well to the habitats found here, as conservation science interns Bryan Minne and Laura Ruysseveldt from Ghent University in Belgium found during their studies here.

The Central American Banded Gecko, Coleonyx mitratus, is uncommon in Laguna de Apoyo Nature Reserve. Photo by Laura Ruysseveldt. 

Bryan and Laura spent a few months in Nicaragua, studying the geckos and other reptiles and amphibians of Laguna de Apoyo Nature Reserve. They turned up some solid information on gecko habitats, particularly regarding the recently introduced Asian house gecko, Hemidactylus frenatus, and its impact on native gecko species.

Field research on lizards and other herps usually includes a difficult process of identification. Photo by Laura Ruysseveldt.

Laura and Bryan also surveyed several habitats in the Laguna de Apoyo Nature Reserve, in search of each of the reptile and amphibian species that could be found here. They were the first to find the Central American Banded Gecko (Coleonyx mitratus), a charismatic little animal that tends to stay on the ground, rather than in trees. 

Asian house geckos (Hemidactylus frenatus) doing what they do best, which is among the reasons why they are now so abundant in Nicaragua, only a few decades after the first individuals arrived. Photo by Laura Ruysseveldt.

Bryan and Jeffrey review trees for study plots for gecko habitats in Laguna de Apoyo Nature Reserve, Nicaragua. Photo by Laura Ruysseveldt.

Field work included systematic reviews of habitats for geckos to determine how native species, particularly the Yellow-headed Gecko (Gonatodes albogularis) and the Yellow-bellied Gecko (Phyllodactylus tuberculosus) are responding to the invasion of the Asian House Gecko (Hemidactylus frenatus). Their project yielded some rigorous results, and they sweated a lot on long walks, but we are sure they are happy they came!

The Black-bellied Racerunner, Cnemidophorus deppei, is elusive and difficult  to photograph in the wild. Photo by Laura Ruysseveldt.

The Black Iguana, Ctenosaura similis, is an effective symbol for forest destruction in Nicaragua, as poachers often set forest fires to hunt them during the dry season. Photo by Laura Ruysseveldt.

We often ask ourselves how can we assure the protection of lizards and other wildlife in Nicaragua. By sponsoring conservation science internships for students such as Laura and Bryan, we are learning more about our herpetofauna, including what problems each species may be facing. For instance, while surveying the reptiles in our area, the staff at Estacion Biologica, along with Laura and Bryan, witnessed an attempt to capture a large Black Iguana (Ctenosaura similis). We stopped the hunters as they chased the animal through a ravine, and then reported the activity of these people to the park rangers, who responded within minutes to warn the people that hunting is illegal inside the Laguna de Apoyo Nature Reserve.

The Rose-bellied Lizard, Sceloporus variabilis, is a close relative to several fence lizards found in the US and  Mesoamerica, and is abundant in rocky and dry areas. Photo by Laura Ruysseveldt.

Forest fires are often set to hunt iguanas and mammals. The fires destroy the habitat of and kill many smaller reptiles and other mammals, too. Laura and Bryan participated in extinguishing a forest fire that burned several hectares, just behind Estacion Biologica. Many animals live precariously in the forests where humans may abuse them in numerous ways.

Bryan examines a captured specimen before making a presentation on the reptiles of our area to the students of a local school. Photo by Laura Ruysseveldt.

Bryan and Laura returned to their studies in Belgium after completing a detailed, quantitative project as well as lots of time in the jungle, in search of lizards and other reptiles, and hopefully, we can utilize their knowledge to promote better stewardship of wild nature in Nicaragua.

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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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