Biology Reference
In-Depth Information
(b)
(a)
Fig. 8.6
Camilla Hinde's (2006) experiment with great tits. (a) A great tit brood. A speaker is hidden inside the
nest, so begging calls of the brood can be augmented by playback. Photo © Simon Evans. (b) Male parent great
tit. Photo © Joe Tobias.
Table 8.4
Parental response to playback of extra calls (Hinde, 2006) Each
parent responded by increasing its provisioning rate to the brood. The
partner who did not experience the playback also increased its effort.
Treatment
Feeds/hour to the brood
Female
Male
Total
Control (no playback)
15
18
33
Playback to female parent
22
25
47
Playback to male parent
19
27
46
partner effort directly affects the benefit of additional investment by its mate.
If investment yields decelerating returns (as assumed in the model) then greater effort
by one parent should lead to a decline in the marginal benefit of care and so favour a
compensatory reduction in investment by its mate. However, the model ignores a
second, indirect way in which a change in partner effort might influence its mate's
behaviour, namely by conveying information about brood needs. If one partner has
better information about how hungry the chicks are, then the other parent may use the
