Biology Reference
In-Depth Information
(a)
(i)
(ii)
Image not available in this digital edition.
(d)
Fig. 6.16
An example of the benefits and costs of group living. (a) (i) A cliff swallow
breeding colony. (ii) A bird at its nest entrance. Individuals gain benefit from the colony,
which is an information centre enhancing food finding (ephemeral insect swarms; Brown
1988). (b) However, there are also costs; the number of blood-sucking hemipterans
(swallow bugs,
Oeciacus vicarius
) on nestlings increases with colony size and (c) nestling
body mass declines with increasing numbers of these ectoparasites. (d) Two nestlings,
both 10 days old. The one on the right is from a fumigated nest, where the bugs were
removed. The one on the left is from a naturally infested nest in the same colony. Photos
(a) and (d) © Charles R. Brown. Figures (b) and (c) from Brown and Brown (1986). With
permission of the Ecological Society of America.
