The effect of neighbours on the mortality of harvester

0[ This study investigates how the density and size of conspeci_c neighbours a}ected the mortality of established colonies[ Data were from a population of 149Ð299 colonies of the red harvester ant ðPogonomyrmex barbatus "F[ Smith#Ł\ on a 09!ha site\ from 0877 to 0884[ 1[ Colonies are more likely to die as they grow older[ 2[ Small neighbours tend to lower the probability of dying[ 3[ The probability of dying varied signi_cantly from year to year[ 4[ There was little e}ect of crowding on mortality[ 5[ There appeared to be no spatial e}ects\ on the scale of 14m\ on the probability of dying[ 6[ Previous work shows e}ects of density on the founding of new colonies and on the reproductive output of established ones[ The results presented here indicate that competition with neighbours rarely causes the death of established colonies[