NC State University Insect Museum

A colleague sent me an interesting article yesterday about bumble bees (Apidae: Bombus spp.) co-opting bird nests that's worth a read. It's not unusual for some species of bumble bees to establish in abandoned vertebrate nesting sites (some may even be obligate users of these old nests), and the authors (Pierre Rasmont, A. Murat Aytekin & M. Suleyman Kaçar) list some common examples involving rodents - e.g., voles, lemmings, squirrels, and sousliks.

Bumble bee nests are also frequently observed in abandoned bird nests, mainly in bird boxes (see article and below). I remember helping some friends back in Arkansas remove a Bombus nest that had established in an old blue bird box. (And I also remember all the nest's cool cohabitants - various arthropod scavengers, tiny beetles, psocopterans, etc.) The authors even note that Wagner (1937)* attributes the expansion of some bumble bee ranges to man-made bird boxes.

What interests me about this paper is that the authors describe how Bombus niveatus muscles in on occupied bird nests - quickly taking them over without overt aggression. Rather than sting and attack the bird, the bumble bee queen "continuously rearranges the nesting material covering so the bird's clutch or even the young birds [are covered]" (p. 254) - essentially gaslighting the bird (what nest? there's no nest here) until she flies off, never to return ("when B. niveatus settles in an abandoned Redstart's nest, it does not rearrange the nesting material in the same way. This suggests that the dogged rearranging could be an active, ad hoc technique to get rid of the bird"; pg. 254). The authors never observed the redstart attempting to defend her home turf.



*Wagner A. C. W. 1937. Die Stechimmen (Aculeaten) und Goldwespen (Chrysididen s.l.) des westlichen Norddeutschland. Verhandlungen des Vereins für naturwissenschaftlischen Heimatforschung zu Hamburg 26: 94-153.