Bees Tell Birds to Buzz Off: How Bumblebees Steal Birds' Nests

May 28, 2013 — A new study highlights the 'parasitism by theft' of bumblebees that invade birds' nests and claim them as their own. Their warning buzz helps bumblebees to "scare" the bird away from the nest. The work by Piotr Jablonski and colleagues, from the Laboratory of Behavioral Ecology and Evolution at Seoul National University in South Korea, is published online in Springer's journal, Behavioral Ecology & Sociobiology.

Conspicuous warning signals -- visual, auditory or mixed -- help prey to deter predators by signaling the presence of defenses (chemical, mechanical, etc). These warning signals help the predator to remember how to recognize the distasteful or poisonous prey that should be avoided.

Birds are predators of bumblebees. In temperate forests, birds and bees use tree cavities for their nesting activities. Because bumblebees prefer cavities filled with plant materials for insulation, they may benefit from stealing freshly built nests from the birds.

Jablonski and team studied the interactions between bumblebees and cavity-nesting Oriental and Varied tits in nestboxes. They were particularly interested in whether bumblebees attempted to settle in those boxes to which the birds brought fresh nest materials, and whether their warning signals provided an advantage in taking over the nests from birds.

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