Wednesday, April 20, 2011
Iberian Water Frog Chorus
Well its been a while since my last post! Earlier this month I was in south-west Spain for eleven days on an annual ecological genetics field course (a 2nd year undergraduate course) based around Zahara de los Atunes, near Tarifa. One of the study sites is the Arroyo del Tiradero in Parque Natural de los Alcornocales, a beautiful mountain stream where students study mate guarding in the pond skater (or water strider) Aquarius najas. Our particular stretch is lined with alder trees and surrounded by cork oak dehesa-like habitat. Interesting bird species here include Iberian Chiffchaff, Western Bonelli's Warbler, Short-toed Treecreeper, Cirl Bunting, Firecrest and Hawfinch, while there is often a spectacular array of raptors overhead. As well as being fantastic for bird song, at least when the wind is not blowing, there is an almost constant chorus of singing Iberian Water Frogs (Rana perezi) at this time of year. The vocal output tends to fluctuate from quiet periods when just one or two individuals are singing to almost deafening (at close range at least) crescendos during communal displays involving many frogs. This is likely to be lekking behviour (Ruff and Black Grouse being good examples in birds) but it is difficult to approach these frogs to closely observe them as they either go silent, or dive underwater.