干旱区生态环境知识资源中心

The dramatic spatial and temporal variation in rainfall and the resource pulses which these trigger provide a challenge for predicting consumer-primary productivity dynamics especially in arid systems. In particular, understanding is needed of the degree to which boom-bust dynamics drive arid systems. Here, we assess the response of birds (diurnal raptors, nocturnal rodent-specialist raptors) and rodents to a resource pulse in the western Simpson Desert across a 43-month study period that finished in May 2011. Three rainfall pulses in rapid succession from February 2010 to March 2011 underpinned a big rain’ event. Rodent populations irrupted within 6-9 months of the first of the three rainfall pulses (in February 2010). Two rodent-specialist raptors; the letter-winged kite, Elanus scriptus, and eastern barn owl, Tyto javanica, appeared in the area within 6-9 months of the start of the rodent irruption. By comparison with the rodents, barn owl and letter-winged kite, diurnal raptors responded rapidly to the February 2010 rainfall event. When comparing surveys carried out the week prior to the February rainfall event with May 2010, raptor richness increased from two to six species and the index of abundance, measured as mean sightings per km, increased from 0.07 to 1.34. These findings emphasize that the 2010-2011 resource pulse was an ecologically significant event. Our results confirmed the link between big rains and rodent irruptions but they also highlighted the occurrence of finer-scale temporal fluctuations that are less easily accounted for by rainfall patterning.