Introduction • the key angles of neurobiology and ecology. In chapter 4, Beecher and Burt
present an update on a long-term research program examining the rules that
young song sparrows (Melospiza melodia) use to decide which songs to learn,
retain, and later use and the role that the social ecology of song sparrows has
played in shaping these rules. Searcy and Nowicki (chapter 5) take a fresh
look at bird song learning by examining the recent nutritional stress hypoth-
esis. They suggest that conditions during early development have long-term
effects on features of the male song, which females can readily perceive, and
on other aspects of male quality, which females cannot easily assess. Hence,
females rely on male song as a reliable indicator of overall male quality. Searcy
and Nowicki review the recent data, which are mostly in agreement with the
nutritional stress hypothesis.
Pravosudov (chapter 6) also addresses effects of nutritional stress during
development, but his focus is on the hippocampus and spatial memory. Work
on spatial memory in birds has provided a clear link between the ecological
need to store food, a relatively enhanced spatial memory used to retrieve the
cached food, and the relative volume of the hippocampus, the brain region
processing spatial memory. Given the importance of spatial memory for the
survival of certain bird species, Pravosudov and colleagues predicted that hip-
pocampal development and hence spatial memory would remain intact even
under nutritional stress. Their data reviewed in chapter 6, however, refute that
prediction and suggest that constraints during development preclude the insu-
lation of certain brain regions from nutritional stress. The chapters by Searcy
and Nowicki and Pravosudov add the important dimension of development
to understanding animal cognitive ecology.
In chapter 7, Sol relies on recent data to address the old question of why
some animals have large brains relative to body size even though such brains
incur substantial costs in terms of delayed maturation and high maintenance.
Sol then reviews recent studies providing support for the cognitive-buffer
hypothesis, which states that a relatively large brain is associated with an en-
hanced ability to handle novel situations and hence with increased probability
of survival in novel or altered environments.
With few exceptions, all animals have to make decisions within the four
general categories of feeding, predator avoidance, interactions with competi-
tors, and sexual behavior. Part III focuses on cognitive aspects of decisions
made within two of these behavioral categories: reproduction and antipreda-
tor behavior. Female choice of mates has been studied for a long time, and
as Ryan, Akre, and Kirkpatrick note in chapter 8, it is well established that
females choose mates based on their perceived quality. It is also clear that such
female choice has generated sexual selection, which is responsible for the evo-
lution of many features of male mating signals. Less apparent, however, are