Community Interviews. We interviewed one hundred people from different localities along the coast of Oaxaca and the Tehuantepec Isthmus to gather information about the use and practices towards iguanas within their communities, and to evaluate people’s perception towards the benefit of protecting the Oaxacan Spiny-tailed Iguana. The interview was conducted through an open discussion based on a questionnaire that was intended to make people feel comfortable.

Based on these conversations, we can establish that generically “iguanas” have been an important part of the culture and development of Mexican society as the subjects of consumption and trade. However, the increase of human activities and loss of habitat has altered the populations of iguanas and many other wild species.

The people we spoke to asserted that hunting iguanas increases during the egg-laying season (February-March). However, catches are also made occasionally throughout the year, mainly by people working in the fields and by those that survey trees or fences that divide land ownership. Iguanas are captured primarily for meat consumption, because it is a free available resource and is mostly very tasty. However, there are people who capture them to sell their meat, as pets, or just for fun. In regions with some degree of urban development, people have stopped working in fields, so hunting iguanas has become an occasional activity. Moreover, they know that iguanas are prohibited for trade, that their populations have decreased by the action of hunting, habitat destruction, and the introduction of exotic species (cattle, poultry, dogs, and cats). Unfortunately, they believe that iguanas are used as a resource due to lack of government support for agriculture, fisheries, and the lack of paying jobs. People living in interviewed communities expressed willingness to participate in conservation, together with government and private institutions as long as their rights and their natural, social, and economic resources are respected, and that they are provided with short-term results to benefit their communities.

In the absence of sufficient information about the use and conservation of iguanas, it is essential to start with educational programs to raise awareness on the conservation and sustainable use of species that are in some category of protection, and especially for the iguanas.

Genetics Laboratory Work. From each of the 370 captured iguanas, we withdrew 0.5 ml of blood from the caudal vein and preserved it in 96% alcohol. The DNA was extracted using the salt extraction method of Aljanabí and Martinez (1997). We have successfully conducted PCR reactions on five fluorescent microsatellite markers (Pec-01, Pec-03, Pec-16, Pec-20, and Pec-25) and collected allelic data for all populations. Genetic analysis with four markers for mitochondrial and nuclear DNA is still preliminary.

DISCUSSION

Populations of Oaxacan Spiny-tailed Iguanas are mostly in small fragments or patches as a result of the development of human activities. Vegetation structure indicates that generally this iguana is mainly distributed in dry forests throughout its range as reported by Rioja et al. (2012) and in Nizanda by Díaz-Juárez and Reynoso (submitted). Ctenosaura oaxacana prefers trees with small holes in proportion to their body size, where they can fit tightly. The distribution of iguanas is limited to the presence of tree species with holes, but can also live in fences made with this same kind of tree. Díaz-Juárez (2014) observed that the trees mainly used as refuges are Mimosa eurycarpa (Gui’chi bateede, 93%), Mimosa tenuiflora (Gui’chi bu, 4%), and only occasionally (1.1%) iguanas were captured in the trunk of Chloroleucon manguense (Gui’chi dxita) and Caesalpinia platyloba (Tepeguaje). In our fieldwork, we observed that the topographical composition changes between each locality in the Isthmus of Tehuantepec and the coasts of Oaxaca.  These areas are dominated by tropical deciduous and semi-deciduous forest. We identified new species of trees that are used as shelters by Oaxacan Spiny-tailed Iguana: Lysiloma microphyllum, Genipa americana, Byrsonima crassifolia, Acacia coulteri, Cordia elaeagnoides, Comocladia engleriana, Crescentia alata, C. cujete, Haematoxyllum brasiletto, and Havardia campylacantha. Unfortunately, habitat loss and land use change for agriculture or livestock is a common aspect of the landscape in the whole distribution area of this iguana.

Morphometric data indicate that the average length of females and males (12.6 ± 1.15 cm), coincide well with those reported by Díaz-Juárez and Reynoso (submitted), as well as for body mass (67.6 ± 21.02 g). Topographic composition also appears to influence dispersal, morphology, and perhaps social structure. Morphometric data revealed that populations in the Isthmus of Tehuantepec have similar proportions to those reported by Díaz-Juárez and Reynoso (submitted), except in La Venta where the largest iguanas were captured at 18 cm SVL and 200 g body mass. Along the coast of Oaxaca, the smallest sizes were found in the northern coast with a maximum length of 16.5 cm and weight of 145 g. Contrasting, the southern coast of Oaxaca reported the larger sizes of 17 cm SVL and 180 g body mass.

The skin color of Oaxacan Spiny-tailed Iguana changes slightly throughout its distribution, mainly in males. Iguanas along the Oaxacan coast were observed with small white spots on the back and pigmentation from yellow to orange on the belly. In contrast, in the Isthmus Tehuantepec they have small white dots and dark bands and the ventral region is beige.

Overall, we observed that the sex ratio does not differ from an even 1:1 (χ² = 14.7, P = 0.54) and compares to that estimated by Díaz-Juárez and Reynoso (submitted) in Nizanda where the proportion was also 1:1 (χ²= 0.338, P=0.56). We observed that this species increases its vagility during the egg-laying season (February-March), hatching season (June-August), and breeding season (December-January). However, hunting and fragmentation also might be influencing these results (Díaz-Juárez and Reynoso, submitted).

The Isthmus of Tehuantepec and the coast of Oaxaca have marked fragmentation, which has caused a considerable reduction among the populations of iguanas. According to the commentaries of people, it is becoming less common to find these iguanas in the fields, and even some young people are unaware this species exists.

People believed that legislation or season closures on the use of ctenosaurs and other wildlife species should be established. In some localities, people are willing to organize and work to ensure that there is no looting and misuse of Oaxacan Spiny-tailed Iguana, and some want to build small iguana programs where they can establish a method of partial-incubation of eggs with the aim to increase recruitment of individuals to populations.

Survival for the Oaxaca Spiny-tailed Iguana is possibly related to protecting the microhabitat that contains trees preferred as refuges. Therefore, it is important to expand the ecological and demographic studies at sites that were sampled to determine the temporal and environmental variability characterizing this species, and provide basic information such as population density, life history, home range, population structure, and behavior.

CONCLUSIONS

Knowledge of the natural history of the Oaxaca Spiny-tailed Iguana is essential to provide information to people and create awareness about the conservation of wild populations of C. oaxacana and other iguana species, habitat conservation, and their sustainable use. Here we show that with a relatively small number of individuals captured along the distribution range of a species with a complex distribution pattern, it is possible to obtain a great variety of relevant information at a low cost and in a short time frame. Information on aspects of habitat, environment, natural history, morphometry, and demography were obtained. Furthermore, information generated from the genetic analysis will determine the viability and genetic variation of populations. Therefore, it is advisable to carry out such studies with species that are in some category of risk, are economically important, or endemic, such as the Oaxacan Spiny-tailed Iguana.