April and May bring special opportunities for outdoor encounters with newly arrived, migrating birds. Weary after long flights, and easier to see before buds unfold to become leaves, these little feather balls arrive from their wintering grounds in the United States, Caribbean, and Central and South America. As Canada’s longer days and warmer temperatures jump-start native plants and animals, habitats come to life, offering food, shelter and nesting opportunities for these seasonal residents. The Canada warbler and Eastern wood-pewee are two species at risk of becoming extinct and facing serious challenges.
Canada warblers (Cardellina canadensis) are bluish grey from above, with a streaked black necklace on a yellow breast. Both males and females have this distinctive necklace. Weighing only 9 to 13 grams (0.32 to 0.46 ounces), with lengths of 12 to 15 centimetres (4.7 to 5.9 inches) and wingspans of 17 to 22 centimetres (6.7 to 8.7 inches), they are one of many forest-nesting warbler species. They inhabit moist, shady forests with abundant plant undergrowth. Their summer range extends from Nova Scotia to the Yukon. Roughly 82 per cent of the population nests in Canada.
Males arrive in mid-May, later than many other warblers. Their song is an irregular, staccato burst of “chip, chupety swee-ditchety.” Females build nests near or on the ground in dense cover. They make nests with decayed leaves, grass, lichens, and mosses, and often line them with rootlets.
They nest and hunt in thickets near water, brushy ravines, forested bogs, and wetlands. I enjoy watching these expert insect-catchers catching beetles, mosquitoes, flies, moths, and caterpillars. They supplement their diet with snails, spiders, and worms. Luckily, these birds aren’t particularly shy and frequently hunt in the tangle of red osier dogwoods, lilacs, and quince in front of our house.
Females lay four or five eggs, which they incubate for about 12 days. The chicks stay in the nest for about 10 days and fledglings remain dependent on the adults for two or three weeks. Canada warblers begin to leave in mid-August for the long flight to overwinter in northern South America.
The Eastern wood-pewee (Contopus virens) is a small, grey-brown flycatcher that favours hardwood forest habitats and the margins of small forest clearings, meadows, roadsides, and ponds. Sexes look similar, and they are slightly larger than Canada warblers. Usually seen in the middle of a leafy hardwood tree, they wait on a bare branch to fly out and snatch passing flies, bugs, butterflies, moths, bees, wasps, beetles, grasshoppers, crickets, stoneflies, or mayflies. In our Pomquet woodland, I often hear their “pee-a-wee” song slurring up and down, long before seeing one. The species is representative of tyrant flycatchers (Tyrannidae), a family of 400 species occurring throughout North and South America. They are the largest known bird family.
Eastern Wood-Pewee nesting habitat in eastern North America includes hardwoods, mixed woods (hardwoods and softwoods), or pine plantations. They build an open-cup nest using grasses, bark, and lichens, attached with spider webs to a horizontal tree branch. Nests are located 15 to 60 feet (4.6 to 18.3 metres) up in the trees, most often around 30 feet (9.1 metres). Oaks (Quercus), pines (Pinus), birches (Betula), and maples (Acer) are preferred nest trees. The female usually lays three eggs, translucent-white with brown flecking. Males will aggressively defend the nesting area, often against species like least flycatchers, American robins, chipping sparrows, and red-eyed vireos.
Eggs hatch in 12 to 14 days, with both parents delivering food to helpless nestlings. Youngsters typically fly 15 to 17 days later. Adults will perch on a nearby branch and call out to any fledgling that ends up on the ground, keeping contact with them and providing food until the young can fly. During that time, they are vulnerable to predators, including domestic cats.
New science
Tracking annual trends of bird populations has involved hundreds of Maritime observers for decades and is a fine example of citizen science. Data for the first Atlas of Breeding Birds of the Maritimes was collected through 1986 to 1990. Observations for the second atlas were gathered over another five-year period (2006 to 2010).
This information was compared with documented forest changes in a paper published last year in Nature, Ecology & Evolution, titled “Forest degradation drives widespread avian habitat and population declines.” The authors,
Matt Betts and his colleagues, determined an estimated loss of 33 to 104 million birds in the Maritimes from 1985 to 2020, due entirely to forestry practices. They established population trends for 54 species of forest birds. The authors found a direct correlation between rapidly dwindling losses of mature forests and declines of bird populations that use those forest habitats. Mature forest losses are highlighted as the dominant cause of their mortality.
The authors provide scientific proof of what nature lovers have seen and tabulated for decades. Wildlife observers have witnessed healthy forest habitat losses over lifetimes. The total forested areas in the Maritimes haven’t changed much, but landscape-scale clear-cutting, herbicide use, and mature forest replacements with
plantations and pioneer species regeneration have drastically altered the type and age of forests.
This forest degradation is causing the decline of birds and many other mature forest wildlife species. Mammals, amphibians, reptiles,
cold-water fish, insects, mosses, lichens, fungi, and many plant species depend on mature, diverse forests to provide all their habitat requirements. Their needs include food, shelter, den/nest sites, vernal pools and shade for ground cover plants as well as cool, moderated water flows into streams
for salmon and trout.
Planet for profit
Government departments that have narrow, limited responsibilities at federal, provincial or municipal levels oversee this habitat demise. Species like Atlantic salmon are jurisdictionally insulated from forestry activities
that can make river channels look like old Roman roads in summer. Employees can only operate within their department’s mandate. The
collective departments rarely muster the will and means to deal effectively with serious ecological issues.
The heads of provincial governments and forest industries apparently value “woodpiles at roadsides” ahead of the long-term health of forests and wildlife habitats. Mark Carney, former governor of the Bank of Canada, said it succinctly: We are “trading the planet for profit.”
New Brunswick, Prince Edward Island, and Nova Scotia provincial governments and their policymakers have allowed forest degradation and wildlife attrition on public and private lands for decades. They’ve been lounging in the back seats of a forestry bus driven by the industry, with no public hands on the steering wheel. We’re paying foxes to control the chicken coop.
Forest harvests that maintain ecologically healthy Maritime forests would vastly improve wildlife habitats. Then Canada warblers, Eastern wood-pewees, and other wildlife populations that need mature forests could begin to recover.
If you own or manage a woodland property, consider leaving some elder trees to develop nest holes. And avoid loud human woodland intrusions during May, June, and July.
Silence can help their singing season.