Normally when frogs and toads share the same pond, their mating occurs at different times. However, as the photo shows, occasionally a late coming frog (the one with the white throat) may turn up on the toad dating scene. You may see them trying to mate each other but the union will be sterile. Horny male toads and frogs also sometimes latch onto big goldfish. Most fish will survive this, unless the frog happens to clasp their gills. If a male toad clasps another male it makes a release call, a kind of squeak, which tells the mating toad to let go (Wells 1977) As fishes don’t make this noise, they continue holding on.
When two species share a pond, female frogs, that are clasped by a male of the wrong species, are not entirely helpless. They may react by either refusing to release the eggs, or releasing just a tiny amount so as to get the male off their backs – literally (Hettewey et al., 2009)
REFERENCES
Hettyey, A., Baksay S., Vagi, B. & Hoi, H., (2009) ‘Counterstrategies by female frogs to sexual coercion by heterospecifics,’ Animal Behaviour, 78, 1365–1372
Wells, K. D., (1997), ‘The social behaviour of anuran amphibians,’ Animal Behaviour, 25, 666-693