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Use of Bomb Crater Ponds by Frogs in Laos
The Ho Chi Minh Trail used by North Vietnamese and Pathet Lao forces during the Indochinese Conflict (1961-1975) passed through the limestone karst region in east-central Laos (Khammouan Province) that is presently classified as Hin Namno National Biodiversity Conservation Area (NBCA) (Timmins and Khounboline 1996). Aerial bombing of the region during the conflict has left many large craters that today hold water even into the dry season (November-April) (Fig. 1).
Amphibians are known to have colonized a wide variety of human-made sources of water, such as rain and drainage catchments, windmill wells (Burkett and Thompson 1994), rice paddies and their associated concrete ditches (Fujioka and Lane 1997), reservoirs (Boniecki 1996), irrigation canals (Schneider 1997), road-ruts (Adams and Lacki 1993), and ponds at former mine sites (Lacki et al. 1992; Turner and Fowler 1981). D. R. Karns (pers. comm.) found heavy use by both larval and adult salamanders and frogs of crater ponds created by exploded ordnance at a military test site (Jefferson Proving Ground, Indiana, USA). We report here on the use by frogs of the artificial ponds at the bottom of bomb craters formed during wartime in Laos.
Twenty-two craters along a one kilometer stretch of road (17 deg 29.82'N 105 deg 42.41'E to 17 deg 30.09'N 105 deg 42.68'E) slightly west of the Hin Namno NBCA boundary were sampled for presence of amphibians during the dry season in mid-Februrary 1998. The craters were surrounded by secondary growth and scrub, and were within 1 km of large limestone karst formations. Crater ponds were...