Central place foragers, such as pollinating bees, typically
develop circuits (traplines) to visit multiple foraging sites in a manner that
minimizes overall travel distance. Despite being taxonomically widespread,
these routing behaviours remain poorly understood due to the difficulty of
tracking the foraging history of animals in the wild. Here we examine how
bumblebees (Bombus terrestris) develop and optimise traplines over large
spatial scales by setting up an array of five artificial flowers arranged in a
regular pentagon (50 m side length) and fitted with motion-sensitive video
cameras to determine the sequence of visitation. Stable traplines that linked
together all the flowers in an optimal sequence were typically established
after a bee made 26 foraging bouts, during which time only about 20 of the 120
possible routes were tried. Radar tracking of selected flights revealed a
dramatic decrease by 80% (ca. 1500 m) of the total travel distance between the
first and the last foraging bout.