Experimental repatriation of boreal toad (Bufo boreas) eggs, metamorphs, and adults in Rocky Mountain National Park

  • Published source details Muths E., Johnson T.L. & Corn P.S. (2001) Experimental repatriation of boreal toad (Bufo boreas) eggs, metamorphs, and adults in Rocky Mountain National Park. The Southwestern Naturalist, 46, 106-113.


This study is summarised as evidence for the following.

Action Category

Translocate toads

Action Link
Amphibian Conservation

Head-start amphibians for release

Action Link
Amphibian Conservation
  1. Translocate toads

    A replicated, before-and-after study in 1995–1999 at two sites within a National Park in Colorado, USA (Muths, Johnson & Corn 2001) found that a breeding population of boreal toads Bufo boreas was not established from translocated eggs. At one site, only 12 tadpoles were recorded during the first week after release. Following that only two toads were recorded in 1997. At the other site 333 metamorphs were captured and marked in the first two weeks, but none were recorded in 1997–1999. Hatching success did not differ significantly between the original and release sites (69 vs 38–72%). Seventeen eggs masses were collected in July 1995 and June 1996. Half of nine, and six complete egg masses were translocated to two sites, where toads had been absent for five and eight years. A small number of eggs were placed in predator-proof boxes to compare hatching success between original and release sites. Following translocation of eggs, a 0.01–0.09 km2 area was searched 1–3 days/week in April–September 1995–1999. Metamorphs were toe-clipped.


  2. Head-start amphibians for release

    A before-and-after study in 1995–1999 of boreal toads Bufo boreas in a National Park in Colorado, USA (Muths, Johnson & Corn 2001) found that captive-reared and released toads did not establish a stable breeding population. Eighteen of the 800 released metamorphs were recorded one week after release, but none in 1997–1999. Unmarked metamorphs were found in 1996–1997. Fifty-six of the adult toads released were recaptured during the first three months, but none were seen in following years. Nine eggs masses were collected from the wild in July 1995. Half of each egg mass was captive reared. In September 1995, 800 captive-reared metamorphs were toe-clipped and released. The site was monitored for the following week, twice monthly in May–June 1996 and then weekly. One hundred toads were reared and released in July 1996. These were monitored on alternate days in July–September and then weekly until November. Toads had been absent from the release site for five years.


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