TEMPORAL PARTITIONING OF A FLORAL RESOURCE BY TERRITORIAL HUMMINGBIRDS

Most studies of territoriality in hummingbirds have focused on intrasp ecific competition for resources and the consequences for the spatial distribution of individuals within a habitat. As a result, we know lit tle of the effects of interspecific competition for resources and less still of temporal resource partitioning. Here I describe the interact ions of four species of tropical hummingbird which defended the same t erritory at different stages in the flowering period and at different times of the day. The pattern of territory defence was greatly influen ced by the dominance hierarchy between species and the costs and benef its of territory ownership. I used a simple economic model to calculat e the predicted territory size based on four potential strategies, Hum mingbirds appeared to be defending territories of the smallest economi cal size, agreeing with two hypotheses: (1) that hummingbirds minimize the cost of territory ownership and (2) that hummingbirds maximize th e time spent sitting, The model predicted accurately the observed patt ern of territory acquisition; hummingbirds initiated defence as soon a s the territory contained sufficient resources and were either displac ed by a larger species or replaced by a smaller one as the value of th e territory changed.