Study

Increasing populations of the green toad Bufo viridis due to a pond project on the island of Samsø

  • Published source details Amtkjær J. (1995) Increasing populations of the green toad Bufo viridis due to a pond project on the island of Samsø. Memoranda Societatis pro Fauna et Flora Fennica, 71, 77-81

Actions

This study is summarised as evidence for the following.

Action Category

Remove or control fish by catching

Action Link
Amphibian Conservation

Create ponds for green toads

Action Link
Amphibian Conservation

Pay farmers to cover the costs of conservation measures

Action Link
Amphibian Conservation

Restore ponds

Action Link
Amphibian Conservation
  1. Remove or control fish by catching

    A replicated, before-and-after study in 1986–1993 of ponds on the island of Samsø, Sweden (Amtkjær 1995) found that fish and eel Anguilla anguilla control was short-term and did not tend to increase breeding success by green toads Bufo viridis. Breeding was successful in two and failed in two of six ponds with just fish removal. One of the ponds was colonized by adults two years after fish and eels were removed, but breeding was not recorded. Only one male was seen in one of the ponds that was enlarged and had fish removed. Fish or eels were reintroduced to ponds within 1–2 years. In winter (1986–1993), fish were removed from six ponds (three twice). Seven ponds had fish removed and were enlarged. Ponds were monitored by call and torch surveys and by counting tadpoles and metamorphs during 4–6 visits in April–September.

     

  2. Create ponds for green toads

    A replicated, before-and-after study in 1986–1993 of 29 created ponds on the island of Samsø, Sweden (Amtkjær 1995) found that green toads Bufo viridis used 17 ponds and bred in 12. Breeding was successful in 10 of the 12 ponds. Toads colonized the ponds over three years. The ponds were created in 1989–1992. Private owners were offered payment by the county to build ponds, provided fish, crayfish and ducks were not introduced and a 10 m pesticide-free zone was maintained around each pond.

     

  3. Pay farmers to cover the costs of conservation measures

    A study in 1986–1993 of payments to landowners to create ponds on the island of Samsø, Denmark (Amtkjær 1995) found that landowners created 29 ponds following payments, of which 17 were colonized and 12 used for breeding by green toads Bufo viridis. Breeding was successful in 10 of the 12 ponds. Toads colonized the ponds over three years. Private landowners were offered payment by the county to build ponds. Twenty-nine ponds were created in 1989–1992. Fish, crayfish and ducks could not be introduced and a 10 m pesticide-free zone was required around each pond.

     

  4. Restore ponds

    A replicated study in 1987–1993 of 10 ponds on the island of Samsø, Sweden (Amtkjær 1995) found that restoration only resulted in successful breeding by green toads Bufo viridis in one pond. A year after pond cleaning, breeding was recorded in one pond, only males in another and no toads in the third pond. Only one male was seen in one of the seven ponds that were enlarged and had fish removed. In winter 1987–1991, three ponds were cleaned due to eutrophication. Seven ponds had fish removed and were enlarged. Ponds were monitored by call and torch surveys and by counting tadpoles and metamorphs during 4–6 visits in April–September.

     

Output references

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, terrestrial mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 18

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.


Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape Programme Red List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Bern wood Supporting Conservation Leaders National Biodiversity Network Sustainability Dashboard Frog Life The international journey of Conservation - Oryx British trust for ornithology Cool Farm Alliance UNEP AWFA Butterfly Conservation People trust for endangered species Vincet Wildlife Trust