RED DEER, Alta. — The first person to die of avian flu in North America was a registered nurse in a central Alberta hospital ... highly infectious among birds, rarely infects humans.

while a Scottish biologist speculates that red deer eating sea birds may do so for a source of protein to help them grow antlers.

Take deer and birds, for example. Deer let birds land on them and pick through their fur. This is what’s called a symbiotic relationship, where two distinct species interact and form relationships.