Another important hydrological variable related to temporal variability in water levels is drought or drydown duration (length of time an area is dry). We were able to vary drought duration in the model, and found significant effects on population growth rate. This response reflects the direct effect of drought duration on survival and reproduction. During droughts, snail availability is dramatically reduced (implicitly taken into account in the model), thus increasing the probability of kites dying from starvation. The longer the drought conditions persist, the greater the reduction in kites. The same reasoning applies to kite reproduction. During drought, reproduction is dramatically reduced, and the longer the drought the less opportunity to reproduce.
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