Cooperative Research Units
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Amphibian Occupancy and Effects of Habitat Use on Chemical Exposure in Northern Leopard Frogs (Lithobates pipens) in Iowa Prairie Pothole Wetlands


November 2013 - December 2018


Amphibians living in agricultural areas encounter many challenges. Two factors affecting individuals in these landscapes are habitat loss and pesticides. This project focused on amphibians using agricultural wetlands in Iowa, where row crops such as corn and soybeans dominate the landscape. The goal of the first study was to determine the influences of site characteristics on amphibian presence and success. Occupancy analysis was used to estimate proportion of area occupied by four species as a function of eight covariates hypothesized to affect occupancy: fish abundance, salamander abundance, invertebrate density, vegetative cover, wetland area, water atrazine concentration, surrounding crop land use, and overall wetland health score. The goal of the second study was to understand where and when frogs are most susceptible to pesticide exposure and how that exposure relates to accumulation. We hypothesized habitat use would influence a frog’s exposure to pesticides. 72 Northern Leopard Frogs (Lithobates pipiens) were radio tracked in agricultural wetlands and their survival was assessed. Passive Sampling Devices (PSDs) were used to test for differences in pesticide exposure among grassland, wetland, and agricultural habitats.


Current Staff

Federal Staff: 95

Masters Students: 238

Phd Students: 144

Post Docs: 54

University Staff: 239

5 Year Summary

Students graduated: 673

Scientific Publications: 1905

Presentations: 4236



  • Clay PiercePrincipal Investigator
  • Jennifer SwansonStudent

Funding Agencies

  • ARMI
  • USGS Fort Collins Science Center


Cooperative Research Units Program Headquarters Cooperators

  1. U.S. Geological Survey