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.