I happened to be reading two reports by W. H. Hamilton III
and collaborators on tricolored blackbird populations and biology
when the report of the colony near Soap Lake appeared. Here are some
of my gleanings from the 1994 and 1997 reports, mostly on Calif populations.
1) The 1994 report concluded that Central valley populations were at the
carrying capacity of the region.
2) Populations vary in size considerably from year to year due to fluctuations
in insect availability.
3) The total Calif population dropped from 370,000 in 1994 to 233,000 in 1997.
4) There is some shift in breeding habitat from cat-tail marshes to Himalayan
berry habitat.
5) Tricoloreds are not faithful to birth site. Do not return to site of
birth in following years. (This may be related to disappearance of traditional
sites and establishment of new sites noted in Oregon and Wa.).
6) Are sensitive to human disturbance. Observed to abandon active breeding
sites within a few days of significant human disturbance.

Bob Vandenbosch
Seattle, WA
v at npl.washington.edu