Bivouac

Definition

A temporary, portable nest formed by army ants (Ecitoninae) and driver ants (Dorylus) in which the queen and brood are suspended within a living matrix of interlinked worker bodies. Workers grip one another by the legs to create a dynamic structure that lacks permanent walls or substrate attachment; the entire colony relocates the bivouac daily or near-daily during the nomadic phase of the colony cycle.

Etymology

From French bivouac, originally a military term for a temporary camp without tents, applied to ants by analogy to their shelterless, mobile encampments.

Example

A colony of Eciton burchellii may form a bivouac the size of a basketball beneath a fallen log, with the queen suspended in the central core and larvae distributed among the outer layers of workers; when prey is depleted, the workers disassemble the structure and carry the queen and brood to a new bivouac site.

Synonyms

• temporary nest
• living nest

Related Terms

• army ant
• driver ant
• nomadic phase
• statary phase
• eusociality
• Queen
• worker caste
• larva
• swarm raid

Usage Notes

Strictly refers to the body-formed nests of Ecitoninae and Dorylus; do not apply to the carton or silk nests of other ants. The bivouac contrasts with the statary-phase nest, which is a more fixed structure occupying a cavity or soil excavation. The term is sometimes used loosely for temporary shelters of other social insects, but specialists reserve it for the classic army-ant system.