Tropical Forest Project

Mexico Tropical Dry Forest Project Methods

Our field methods involve a combination of biological surveying and monitoring, habitat quantification, mark-recapture, and tissue collection. The surveying and monitoring techniques reveal the community composition and diversity, along with population sizes and trends. We accomplish this primarily through visual-encounter surveys. The two types of visual-encounter surveys we carry out are transects and area searches. In transects, paths are walked along either features of the landscape (such as trails or streams), or standardized linear routes, often in a series of parallel lines within a certain homogenous habitat type. Every animal of interest is recorded, and a record may include photos, measurements, and microhabitat characterization. Area searches, on the other hand, are a less rigid method, in which a pre-defined area (e.g. 50 x 50m) is searched for a certain time period and specific microhabitats might be searched more than others. Again, every animal of interest is recorded.

The patchwork of deforestation from cattle grazing allows an ideal opportunity to study the effects of grazing on animal distributions. The bare patches on this slope are cleared every year, and are surrounded by intact forest.

Particularly rare, interesting, and/or photogenic animals are taken back to the on-site “lab” for more photos and measurements. We will also be taking DNA samples from some animals. This is usually done through a blood sample or mouth swab, although sometimes more invasive procedures need to be performed. We also test amphibians for a disease spread by a fungal pathogen. We accomplish this by swabbing the animals’ skin to collect DNA and then examining the sample with DNA sequencing technology to determine if the genetic material of the fungus is present. Almost all animals will be returned to the exact spot of capture, although on rare occasions (e.g. a potential new species is found) a specimen may be taken as a voucher.

Mexico Biodiversity Project

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Conservation Issues

Sonoran Strangler Fig.
Tropical species, like this strangler fig, reach their northernmost distribution in southern Sonora, around our study sites.

Spanning several distinct biogeographic zones, the Sierra de los Alamos region of Mexico holds some of the greatest and most distinct biodiversity in all of North America.

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