Evidence for leafy spurge dissemination by birds?

Abstract

Questions are often raised concerning the spread of leafy spurge (Euphorbia esula; E. virgata; and their complex) by birds, particularly, since this noxious weed is often found in inaccessible places and beneath lines and other apparent perches. In a study in 1936, Bakke reported no viable seed passed through the digestive tract of mourning doves. However, that does not rule other passerine birds or dissemination by regurgitation when feeding young.

Citation

Noble, Daniel L. 1980. Evidence for leafy spurge dissemination by birds? Weed Science Society Of America. 8(3): 8.