<P> If regularly disturbed at the nest, magpie pairs will eventually either move the eggs or abandon the clutch altogether, but in the first instance they will defend the nest aggressively . Biologists who have climbed nest trees to measure magpie eggs have reported that the parents recognized them personally on subsequent days and started to mob them, overlooking other people in the vicinity . </P> <P> Many suburban songbird lovers dislike magpies because of their reputation for stealing eggs, but studies have shown that eggs make up only a small proportion of what magpies feed on during the reproductive season . In England, the European magpie also has a reputation for taking eggs, and yet when density of magpie populations increases, songbird density does not decrease; on the contrary, it increases too . </P> <P> In the United States, black - billed magpies are protected under the Migratory Bird Treaty Act, but "(a) Federal permit shall not be required to control...(magpies) when found committing or about to commit depredations upon ornamental or shade trees, agricultural crops, livestock, or wildlife, or when concentrated in such numbers and manner as to constitute a health hazard or other nuisance". State or local regulations may limit or prohibit killing these birds as well . The species is not threatened and in some areas it has benefited from forest fragmentation and agricultural developments . Like many corvids, however, it is susceptible to West Nile virus . </P>

Black and white bird the size of a crow