Ontario Arrival and Departure
North American Migration
After spending a few months in Brazil, Purple Martins will begin their long migration back to North America. There are several paths of migration they could take: follow Central America and Mexico up to the US, island hop across the Caribbean, or follow Central America up partway where they will cross the Gulf of Mexico over to Louisiana and Florida. From there they will use the Central or Mississippi Flyway to reach Ontario. This migration can take weeks or months. Generally, the earliest and oldest martins arrive in Ontario by the fourth week of March if weather permits. The subadults will arrive around the first week of May. The dates and times of arrival vary from location to location.
The first adult martins to arrive at their breeding grounds are termed scouts, the oldest birds, male or female, returning to their nesting site from the previous year. Throughout North America, the timing of the return of adult martins varies from year to year. Adult Purple martins arrive in Ontario at the end of March or the first two weeks in April. Some adult martins will continue to arrive at colonies into the beginning of June.
Subadult Arrival—Begins 4-12 weeks after Adults
Ontario subadults are birds that fledged the previous year and are now returning to North America to select a site and breed. They will begin arriving at the end of May or the beginning of June.
Nest Building—4-6 weeks after arrival
Nest building begins about four to six weeks after martins arrive at their final breeding site. Nests are generally built out of twigs, pine or bean straw, corn fodder, and mud. A mud dam may be constructed at the front of the nest. Final nest construction can take three to four weeks. The last stage of nest building is lining the nest with green leaves. The function of the green leaves is still unknown, but is thought to act as an insecticide or may help in regulating the temperature and moisture levels in the nest.
Laying Eggs, Raising Young, Migration
It will take up to two months to complete this process and to be ready for their migration south. After fledging, juvenile Purple Martins, as well as adults and subadults will congregate at a roost. Large flocks of martins gather to spend the night at these roosts, which are usually situated near water or in trees. Martins will then form smaller groups and begin the migration from these roosts. Although individual roosts remain active for six weeks or longer, individual birds may only stay at a roost for an average of four weeks. They then begin their long migration back to South America. Roosts in Ontario may occur in different places but Walpole Island, Point Pelee, the Grand River, and Long Point are some places to visit.
South American Migration
Most Purple Martins overwinter in Brazil, in large urban roosts, the rainforests, or on rivers in the Amazon Region. While in South America they undergo their annual molt. Though they begin molting in North America, they don’t molt their flight and tail feathers until they have reached South America. Subadults will gain adult plumage, hatching-year birds will get their subadult plumage, and adults will get a new set of adult feathers. Molting replaces damaged feathers and also helps rid the martins of parasites.