Density dependence and colony growth in the ant species Formica neorufibarbis

1. Production of cocoons and numbers of workers in 25-40 colonies of the ant species Formica neorufibarbis were tracked from 1993 to 1998 in order to test for density dependence in either production or survivorship of workers. 2. The percentage of workers lost by colonies over winter increased with increasing worker numbers. 3. There was no evidence that worker production was density-dependent. 4. Food supplementation did not affect worker-cocoon production. 5. Colonies forced to live under small nest rocks produced fewer cocoons, but this effect was never seen under natural conditions. 6. In the field, colonies preferentially utilized large rocks for nests and worker number was positively correlated with nest-rock area.