(5) The nests are definitive enough and at the same time specific enough to
give us excellent evolutionary sequences. These may be correlated with
the known morphological evolutionary relationships of the species. We have
nest sequences of species in the same genus available, information that should
give us a clue to the influence of species divergence upon these behavior patterns.
In numerous instances we also find nest characteristics common to
many species within a single genus or a group of related genera, thus indicating
a long stability of the inherited patterns.