Migration Info The popularity of this bird with the public has led to the almost instantaneous communication regarding the first arrivals on the Gulf coast each year (see the website called "Purple Martin Forum"). In 2002, the birds started to show up during the first part of January, although the bulk of the migration is yet to come. The true winter distribution of North American Purple Martins is difficult to define, because they tend to mix with several other similar species in South America. Mixed flocks of martins form huge roosts in parts of South America, including one flock that roosts in a sprawling petrochemical plant, covering the pipes and catwalks at night. Evidence suggests that birds from many breeding locations make up these flocks; a group of martins marked in a roost in Sao Paulo, Brazil, later turned up in nests in Texas, Louisiana, Missouri, Wisconsin, Kansas, Virginia, Maryland, Pennsylvania, New Jersey, and Ontario. The actual winter range of the two western populations of Purple Martins remains unknown.