It is difficult ot separate the effects of different weather variables because many of them are correlated. In the case of temperature the effects are not only related to the metabolic activity but also to the speed the marsh becomes dry (and unsuitable for the breeding of this species). However, the inter-year variability in temperature (mean temperature from march to august ranged between 18.34 and 20.99C, see data in rbd.ebd.csic.es/Seguimiento/mediofisico/parametrosmeteorologicos/tmed.htm) is much lower than for rainfall (ranged from 24.1 to 238.6). Additionally temperature is unrelated to changes in breeding population size in Doñana, R-square=0.04, F1,14=0.64, p=0.44.