Skip common site navigation and headers
United States Environmental Protection Agency
Exposure Research
Begin Hierarchical Links EPA Home > Research & Development > Exposure Research > Publications/Presentations > End Hierarchical Links

 

Modeling Snake Microhabitat from Radiotelemetry Studies Using Polytomous Logistic Regression

spacer
spacer
Abstract:Multivariate analysis of snake microhabitat has historically used techniques that were derived under assumptions of normality and common covariance structure (e.g., discriminant function analysis, MANOVA). In this study, polytomous logistic regression (PLR which does not require such assumptions, was developed to model habitat use patterns from snake radiotelemetry data. Two case study examples were used: the copperhead ( Agkistrodon contortrix) in a forested habitat in Chesapeake, Virginia, USA, and the cottonmouth (Agkistrodon p. piscivorus in a wetland habitat in Virginia Beach, Virginia, USA. The model was developed based on grid-cell counts of the habitat used by adult snakes that were radiotracked for a minimum of one activity season (early spring through late fall). In addition to PLR modeling, a nonparametric MANOVA procedure based on ranked data from presence versus random sites was developed for comparative purposes. Although the results were similar in terms of the variables chosen by the models, nonparametric procedures lack predictive power, and the conclusions drawn from them are sometimes questionable or difficult to interpret Polytomous logistic regression provides a useful alternative to traditional modeling approaches that require ancillary data from random sites; PLR requires data only from sites used by the snakes, and was developed based on use-intensity categorization. Suggestions for model implementation (e.g., in a GIS) are discussed,

spacer
Citation:Cross, C. L., and C. E. Petersen. Modeling Snake Microhabitat from Radiotelemetry Studies Using Polytomous Logistic Regression. JOURNAL OF HERPETOLOGY 35(4):590-597, (2001).
spacer
spacer
Contact: Chris Siebert - (702) 798-2234 or siebert.christopher@epa.gov
spacer
Division: Environmental Sciences Division
spacer
Branch: Landscape Ecology Branch
spacer
Product Type: Journal
spacer
Published: 12/14/2001
spacer
Related Entries:
spacer
Bullet Item Development of Landscape Indicators for Use in Regional Ecological Risk Assessments
spacer Relationship Reason:   A Project of the Product
spacer
spacer
spacer

 

ORD Home | Search EPA | Search NERL | Search EIMS | Contacts | Help

 
Begin Site Footer

EPA Home | Privacy and Security Notice | Contact Us

Last Updated on Monday, October 22, 2007
URL: http://cfpub.epa.gov