Figure 11.

Field 413 (40°55.88 N, 97°22.38 W), York County, Nebraska (A–F). In 2001 frogs bred in the irrigation ditch (A) and were present by the thousands. Even at this time, the water level (and thus temperature and pesticide levels) fluctuated drastically from one day to the next: the photo in B was taken on 22 July 2001 and photos in A and C were taken on 23 July 2001. (B) All the water has evaporated and only the small pool (white glare) remains. In 2004 seven pairs of frogs bred at the same site when the irrigation ditch filled with rainwater and snowmelt (D; arrow indicates where frog clutches were found). (E) One of the seven clutches. (F) The fields around the irrigation ditch were not planted in 2003 or 2004, and the ditch dried up, resulting in 100% failure of the population at this site for the second year since initial collection. (G) A breeding pond (arrow) in Hitchcock County, Nebraska (40°08.433 N, 101°13.804 W) along the Republican River. All the tadpoles died of desiccation at this site, further illustrating the interaction between pesticides that slow development and delay metamorphosis and the impact of agriculture (and irrigation practices) on amphibian populations.