Title

Shelter availability and use by Mexican Beaded Lizards in a tropical dry forest

Document Type

Oral Presentation

Location

SURC 202

Start Date

17-5-2012

End Date

17-5-2012

Abstract

We investigated factors affecting shelter use by the Mexican Beaded Lizard, Heloderma horridum in a tropical dry forest of costal Jalisco, Mexico. Our study aimed to understand 1) how shelter (burrow) availability varies over the landscape, 2) if beaded lizards choose to inhabit areas that have a high frequency of potential burrows, and 3) how the extreme seasonality of a tropical dry forest might influence microhabitat selection. We hypothesized that there would be a higher frequency of potential shelters in areas that had known beaded lizard use. To test our hypothesis, we ran transects near 10 known burrow sites (5 wet season and 5 dry season) and 5 areas with no known Heloderma horridum activity, recording all potential burrows within a meter of each transect line. We found that beaded lizards tended to choose burrows with sediment roofs and floors, with the remaining potential shelters having tree root or rock components as well. Significantly more potential burrows were found in areas of known use (3.0 shelters/80m transect) than in non-site areas (1.4 shelters/80m transect). A chi-squared analysis showed that beaded lizards also prefer burrows with a west-facing entrance, most notably for dry season sites. Our results suggest that shelters (burrows) may be a limiting habitat feature for beaded lizards and that these lizards are selective in their choice of shelter sites, a result that may also apply to other species that inhabit tropical dry forests.

Faculty Mentor(s)

Daniel Beck, Lisa Ely

Additional Mentoring Department

Biological Sciences

Additional Mentoring Department

Geological Sciences

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May 17th, 3:20 PM May 17th, 3:40 PM

Shelter availability and use by Mexican Beaded Lizards in a tropical dry forest

SURC 202

We investigated factors affecting shelter use by the Mexican Beaded Lizard, Heloderma horridum in a tropical dry forest of costal Jalisco, Mexico. Our study aimed to understand 1) how shelter (burrow) availability varies over the landscape, 2) if beaded lizards choose to inhabit areas that have a high frequency of potential burrows, and 3) how the extreme seasonality of a tropical dry forest might influence microhabitat selection. We hypothesized that there would be a higher frequency of potential shelters in areas that had known beaded lizard use. To test our hypothesis, we ran transects near 10 known burrow sites (5 wet season and 5 dry season) and 5 areas with no known Heloderma horridum activity, recording all potential burrows within a meter of each transect line. We found that beaded lizards tended to choose burrows with sediment roofs and floors, with the remaining potential shelters having tree root or rock components as well. Significantly more potential burrows were found in areas of known use (3.0 shelters/80m transect) than in non-site areas (1.4 shelters/80m transect). A chi-squared analysis showed that beaded lizards also prefer burrows with a west-facing entrance, most notably for dry season sites. Our results suggest that shelters (burrows) may be a limiting habitat feature for beaded lizards and that these lizards are selective in their choice of shelter sites, a result that may also apply to other species that inhabit tropical dry forests.