Amphibians: Manipulate sex ratio within the enclosure

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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How is the evidence assessed?

Effectiveness

35%
Certainty

15%
Harms

0%

Calculating overall effectiveness category

Background information and definitions

By manipulating sex ratios, increased competition between males for a mate could stimulate more breeding calls or mating. However, males from more aggressive species may need to be separated during this time to minimise injury to tank mates, eggs or larvae.

Study locations

Key messages

One replicated study in Australia found that frogs only bred once sex ratios were manipulated, along with playing recorded mating calls and moving frogs into an indoor enclosure which allowed temporary flooding, and had various types of organic substrate.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A replicated, before-and-after study in 1994–1996 of roseate frogs Geocrinia rosea at Melbourne Zoo, Australia found that fertile eggs were only laid after sex ratios were manipulated, females carrying eggs were introduced to males, recorded mating calls were played, and frogs had been moved to an indoor enclosure which allowed temporary flooding and had a mix of organic substrates. The only fertile spawning occurred in spring 1996, which contained 25 eggs, but they were destroyed by fungus. From 1994-1995 , two male and three sub-adult frogs were housed in two outdoor tanks (120 x 60 x 60 cm) with a sub-surface water depth 50-100 mm. Males called when they were in outdoor enclosures, but fertile eggs were not produced until animals were moved to indoor tanks. From 1996, 6–7 frogs were housed in each of the five indoor enclosures.
Study and other actions tested
Referenced paper
Birkett J., Vincent M. & Banks C. (1999) Captive management and rearing of the roseate frog, Geocrinia rosea, at Melbourne Zoo. Herpetofauna, 29, 49-56.

Please cite as:

Jonas, C.S., Timbrell, L.L., Young, F., Petrovan, S.O., Bowkett, A.E. & Smith, R.K. (2020) Management of Captive Animals. Pages 527-553 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

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This Action forms part of the Action Synopsis:

Management of Captive Animals

Related Actions

Actions	Effectiveness	Studies	Category
Amphibians: Manipulate adult density within the enclosure Action Link	No evidence found (no assessment)	0	Synopsis Link
Amphibians: Separate sexes in non-breeding periods Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
Amphibians: Play recordings of breeding calls to simulate breeding season in the wild Action Link	Unknown effectiveness (limited evidence)	2	Synopsis Link