evidence is not sufficient to say that any of these viruses become estab¬ 
lished in viable cycles in their new ecosystems. 
Some intriguing potential applications of these phenomena suggest 
themselves. If the origin of a viremic migrating bird could be firmly 
established by banding or sub-speciation data, the endemic focus of the 
virus could then be predicted. It might thus be possible to carry out 
surveillance of virus activity in countries otherwise closed to investiga¬ 
tion for political or military reasons. For example, the finding of Kemerovo 
virus in blood of a migrating Redstart in 1961 in Egypt could have signalled 
the activity of this virus (actually demonstrated) in Siberia, a potential 
source of origin of the Redstart and the virus. 
As a corollary to the preceding, if the geographic site of an endemic 
viral focus is known it should be possible to predict the origin of a viremic 
or antibody-carrying bird. This could reinforce banding data. Admittedly a 
great deal more scientific knowledge must be accumulated, both concerning 
endemic viral foci and concerning viruses and antibody in birds, before this 
application could be practical. 
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