Are roads and railroads barriers to bumblebee movement in a temperate suburban conservation area?

We investigated how habitat fragmentation affects the movement of marked bumblebees between plant patches in a temperate conservation area in metropolitan Boston. Massachusetts. Our studs was conducted on populations of sweet pepperbush (Clethra alnifolia L. f.) separated by a road and natural woodland. and buttonbush (Cephalanthus occidentalis L.) separated by a railroad. Bumblebees showed high site fidelity and only rarely crossed roads or railroads. When bees captured Lit one sweet pepperbush population were moved across a road to a ne sweet pepperbush population and released, them returned to their original site, some within 20 min of their Capture. When all inflorescences were removed from one sweet pepperbush patch. most bees moved to another sweet pepperbush population on the same side of the road, The results show that while bumblebees have the ability to cross a road and railroad, these human structures may restrict bumblebee movement and act to fragment plant populations because of the innate site fidelity displayed by foraging bees. Moreover, marked bees were almost never observed to move between populations unless they were displaced, or forced to seek additional forage sites. (C) 2002 Elsevier Science Ltd. All rights reserved.