The Red-eyed Vireo arrives regularly during the last four days of April and leaves during the last week of September.  It is our commonest vireo and comes freely into the wooded sections of the city to breed.  One pair even yet comes to nest in a thicket on the ledge in Penn Valley Park, a few blocks from the Union Station.  Red-eyed Vireos are numerous in and about Swope Park, in some of the cemeteries, in the wooded sections bordering the Country Club and other districts within the city and along the bluffs.  The nesting season begins about the second week in May.