An overdeveloped drive to mate?

Wading around wetlands during the frenzy of amphibian breeding aggregations can reveal fascinating sights and sounds. Male frogs have a wide range of strategies for getting the girl. They might attract a female with song, or lurk quietly trying to sneak in a mating. For some of the male frogs, this will be the only opportunity they have to mate in their entire lives. Consequently, they can get a little overzealous, and errors are made. Males will briefly grab onto other males, but then let go when they hear a specialized “release call” that informs them of their mistake. However, there are some situations where the strong drive to mate combines with the lack of an encounter call with a surprising or even grotesque results.

One such unpleasant outcome is when a male frog amplexes a deceased female. The photo below shows a male wood frog found amplexing a dead female. By the look of it, the female was probably dead for a day or more. Who knows how long the male hung on for!

Sometimes the mix-up is less disgusting, but still interesting. Male frogs will sometimes try to mate with other species of frog, or salamanders. These other species can’t produce the appropriate release call, and so the males just keep hanging on. An example of this is the photo below of a pacific chorus frog trying to mate with a California Newt. I spent six years observing pacific chorus frog breeding aggregations, and it is worth noting that I only saw this frog-on-newt mating a handful of nights. Those nights were always the rainiest nights with the highest densities of frogs. I never saw this behavior cause obvious harm to the newts. However, there may be situations where this can be very bad for the salamander.

Perhaps the most unusual cases are when these two errors – dead animal and wrong species – are combined. I have not yet seen this myself. However, I came across a fascinating example of this on the photo-sharing site flickr. Miha Krofel’s photo below shows a male common toad trying to mate with a dead pike! Click on the photo to go to Miha’s photo stream.

mismatch mating - toad and dead spike

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5 Responses to An overdeveloped drive to mate?

  1. Nick says:

    I’ve heard about duck’s mating with other dead ducks, but never about frogs. Pretty wild!
    “Necrophilia among ducks ruffles research feathers”

  2. Dorry says:

    I found your frog on newt photo via Google after telling my family about seeing such a strange site myself February 2012 near Oregon state university. It was just dark when I saw a frog on the back of a newt crossing a paved trail. Like it was getting a ride across. So strange. Do you have any more info about this behavior– a fisheries grad student I asked had never heard of such a thing. Thanks, Dorry

    • mfbenard says:

      Hi Dorry, Glad you found this interesting. There are lots of cases of frogs trying to amplex other species of frogs. Cases of salamanders being amplexed by frogs are less comment, but I’ve talked to a number of other herpetologists who have observed it. All the best, Mike

      • Andyuk says:

        A frog tried to mate with a toad in my pond. I prised him off and both went their seperate ways, unharmed. The frog was soon lurking on top of the frogspawn, waiting for another victim. Its amazing how strong a frogs grip is. They develop body builders arms during the breeding season!

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