House-hunting by honey bee swarms: collective decisions and individual behaviors

Abstract

Thousands of individuals in a house-hunting honey bee swarm make a collective decision for one among many nest sites discovered. We recorded the dances on swarms in a forested area, where one swarm's search encompassed about 150 km 2 and many different sites. We then analyzed swarms in a desert area with only nest sites that we provided and monitored, to study how the swarm winnows multiple finds to a single site over the course of a few days. Most bees did not visit any site, very few visited more than one. Apparently choices were made with little or no direct comparison, through the interaction of two mechanisms: positive feedback through recruitment leading to growth in the number of scouts visiting good nest sites, and attrition reducing activity and recruitment for non-chosen sites. Individual differences between bees substantially affected these dynamics. Scouts varied considerably in amount of dancing and persistence, but most that danced did so vigorously after their first few visits, and then dropped out, ceasing their dancing though continuing to visit the nest site. Dances were nearly twice as long as reported for nectar and pollen. Scouts followed dances of others, and occasionally visited alternative sites, but rarely switched their dancing. When unanimity is reached, the bees must recognize that a decision has been made, break up the swarm cluster, and fly to the nest site. Buzz-running (Schwirrlaufen) probably plays a role here, but we observed less buzz-running than previously reported, and this occurred even early in the process; it might function as a chain-reaction effect triggering the end of the househunting process. Our results suggest that the choice among nest sites relies less on direct comparison of nest sites, and more on inherent processes of positive feedback and attrition by dancers dropping out.

Dancing for a decision: a matrix model for nest–site choice by honeybees

“…A scout that finds a suitable nest site returns to the swarm and seeks to recruit other scouts to visit the site. Scouts communicate the location and quality of the site by dancing (Lindauer 1961;Camazine et al 1999;Seeley & Buhrman 1999) in a way similar to that by which foragers communicate the presence and quality of forage patches (see Seeley 1995;Seeley et al 2000). While the colony is house hunting many scouts may be dancing on the swarm for many different sites, but eventually nearly all the dances are for a single site and the swarm sets off to settle in the chosen nest site.…”

Consensus decision making in human crowds

“…Camazine et al 1999;Seeley & Buhrman 1999;Mallon et al 2001;Britton et al 2002;Pratt et al 2002;Couzin & Franks 2003;Franks et al 2003;Seeley 2003;Dornhaus et al 2004;Seeley & Visscher 2004;Pratt 2005) and, therefore, much more is known about the mechanisms behind consensus decisions in eusocial insect colonies than in vertebrate groups. Two particularly well studied and elegant examples involve nest site choice in swarming honeybees, A. mellifera, and the ant, L. albipennis.…”

Phase transition between disordered and ordered foraging in Pharaoh's ants

“…In insect societies, workers often use multiple interactions and simple rules to produce complex and adaptive behavior at the colony level (7). Examples include foraging (8)(9)(10)(11)(12)(13)(14), nest construction (13,(15)(16)(17)(18), and nest-site selection (19)(20)(21). These examples suggest that phase transitions should occur in insect societies (8,22).…”