Further information can be found at Nature Canada
Purple Martins have declined seriously in parts of Ontario, and are currently declining in the southeast. It is suggested that competition from starlings and sparrows for nest sites as well as climate change have contributed to this decline. Wintering grounds are now monitored for any threats or declines to determine if this is a further cause for concern. According to the recent Ontario census, the species has declined almost 50% since the early ’70s. The species is now being monitored by several citizen scientists
( Barn Swallows, Tree Swallows, Bank Swallows, Cave Swallows, Cliff Swallows, Violet-green Swallows, Purple Martins)
Purple Martins are long-distance migrants, wintering in the Amazon Basin for several months before their return to North America in late December in the south and in April and May in Ontario.
The Purple Martin forages almost entirely in the air over water, or very high where insect biomasses exist. On occasion, the Purple Martin can be taught to pick up dead insects (crickets, mealworms), or scrambled eggs in harsh weather or catch them when they are tossed within their reach.
A usual clutch of 4-5 white eggs is the norm for the species but when there seems to be an abundance of food, it is not uncommon for them to have 6 or 7. The female will brood the eggs for, 15-18 days. Often the male will defend the nest when the female goes out to feed.
Both parents will provide food for the nestlings. After 26-31 days after hatching, the parents will escort the young to staging areas where they will learn to feed on their own as well return to their home colony for up to two weeks.
Despite the claim that the Purple Martin is a mosquito eater, it has been proven that the Purple Martin feeds on a wide variety of flying insects. Dragonflies are also an important part of the diet especially when they are feeding older young who require copious amounts of food. This 1950s claim has now been debunked and considered an advertising ploy.
Older returning Spring Purple Martin males will establish nesting territories in colonies, where multiple-roomed nest boxes or gourds are put up for them. Nests built of grass, pine straw, twigs, corn fodder, or bean straw with a mud entrance ledge to protect the eggs from rolling out are quite common. They seem to use what they can find in the area or what has been introduced in their nesting boxes.
Climate Threat that Face the Purple Martin
Spring weather in Ontario often taken its toll on returning Purple Martins. Continued cold weather and lack of food have decimated populations. Uncommon rainfall occurrences for long periods of time in the Summer have also caused heavy mortality in young when the parents are not available to feed.
Summer Heat Waves
Summer heatwaves endanger young birds in the nest with declining food availability and extreme nestbox temperatures.
Habitat Decline Due to Increased Housing Development
Often prime Purple Martin habitat diminishes when new urban/industrial developments overtake open areas, farmlands as well as lakefront properties. Constant shoreline erosion and rising lake levels continue to effect Purple Martin’s housing availability in southeastern Ontario.