Frogs prefer a quiet place to mate

Posted on September 24, 2012

Of the various ways in which human activities affect freshwater habitats, changes to the natural soundscape are among the least well understood.  It’s possible that human-generated noise has a significant effect on the behaviour and distribution of animal species that communicate acoustically.  For example, noise interference may force breeding frogs to increase their vocal output in calling for mates, and because calling is energy-expensive, frogs may compensate by reducing the time they spend calling.  This idea was tested by recording frog calls in Chiquibul Forest Reserve, Belize.  At one pond site, auto engine noise was broadcast for at least one hour per night, while at a matched control site 1 km away, noise was never broadcast.  All males of the frog species Dendropsophus microcephalus found at both ponds were individually marked to allow recognition throughout the study.   The amount of time that individual frogs spent calling, and the number of times that they visited a site, were both significantly lower at the noisy pond than at the control pond.  Because female D. microcephalus tend to arrive at ponds later in the evening than males, shorter choruses by males are likely to reduce mating opportunities for both sexes.

Reference:  Kaiser, K. et al.  2011.  When sounds collide: the effect of anthropogenic noise on a breeding assemblage of frogs in Belize, Central America.  Behaviour 148, 215-232.