Analysis of information sources in references of the Wikipedia article "Xenotransfusion" in English language version.
Birds often receive cross-species transfusions because they do not have blood types and there are thousands of different species. These procedures are only done to buy time to stabilize a creature in shock. "Whenever you go across species, the red blood cells are destroyed, and it varies how long they last. It can be as short as half a day, or five to six days [...] But what that gives you is time to stabilize the animal and provide other life-supportive measures."