Theresa et al,

I've also read of bird brain weights increasing during spring song and
territory establishment. National Geog. Encycolpedia of Birds has
something if memory serves. If you're interested, email me and i'll look
it up at home tonight. Regardless, here is the reference on Barnea and
Nottebahm:


Author: Barnea-Anat. Nottebohm-Fernando.
Title: Seasonal recruitment of hippocampal neurons in adult free-
ranging black-capped chickadees.
Proceedings-of-the-National-Academy-of-Sciences-of-the-United
States. Nov 8, 1994. v91(n23). p11217(5)
A study of the birth and replacement of neurons in wild
adult black-capped chickadees, Parus atricapillus, shows that new
neurons appear in all seasons but are most frequent around October
and that the birth rate is double that in captive chickadees.
Neuron tracing using a (3H)thymidine injection shows that
they live for a few months. The neurons may be necessary to
store new spatial information and their replacement rate may
depend on hormonal and experiential variables.

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