Hi Janet,

Here are a few references to check out:

McClure, H.E. 1989. Epizootic lesions of House Finches in Ventura Co.,
California. Journal of Field Ornithology 60:421-430 [discusses pox]

Dales, S., and B.G. T. Pogo. 1981. Biology of Poxviruses.
Springer-Verlag, NY.

Forrester, D.J. 1991. The ecology and epizootiology of avian pox and
malaria in wild turkeys. Bull. Soc. Vector Ecology 16:127-148.

Davis, J.W. et al. 1971. Infectious and parasitic diseases in birds. Iowa
State Univ. Press, Ames, Iowa.

Check these and refs therein. These should get you going.

Chris