A hen’s journey

Part 1: The Nest

Nesting is natural

Birds, like people, experience the urge to nest before they welcome offspring into the world. Expectant bird and human parents alike can trace this feeling to the hormone prolactin. Prolactin is released into the blood stream by the pituitary gland, found at the base of the brain.

A hen’s pituitary gland will also release two hormones that stimulate egg production: follicle-stimulating hormone and luteinizing hormone. They trigger ovulation. Once a duck begins to ovulate, a drake can fertilize her eggs—then things begin to take shape.

Size matters

How waterfowl behave once they arrive on the breeding grounds depends on whether they’re capital or income breeders. “Capital” breeders are large-bodied ducks that can store enough energy (calories) to migrate thousands of kilometres and arrive ready to lay a clutch of eggs and incubate them for about 30 days. One example of a capital breeder is the common eider, which can weigh up to 2.7 kilograms.

“Income” breeders like our far-smaller blue-winged teal (weighing in at 400 grams) are unable to sustain the same kind of fuel reserves. When she arrived at the breeding grounds, she started looking for protein- and calcium-rich foods, like aquatic insects, that provide the nutrients she needs to produce a clutch of eggs.

The hen sets about constructing her nest by scraping the earth with her feet and bill to create a shallow, circular depression. She then lines the nest with nearby vegetation and a few feathers plucked from her own body, working to conceal the nest on all sides and from above. She’s ready.

Part 2: The Eggs

To process of producing a clutch of eggs starts with fertilization of the egg by the drake. Once the ovum is fertilized, the egg starts to develop. The yolk provides nutrients to the developing embryo and albumen (egg white) is deposited around it, followed by the shell. About seven days later, the hen will lay an egg.

A blue-winged teal hen will lay between six to 14 eggs, one per day, provided she has the energy required to develop them. Producing a clutch is very energetically expensive. In humans, it can be compared to giving birth to an eight-pound baby once a day for nine to 10 days!

Our little hen has produced a small clutch of seven creamy-white eggs, and she will spend nearly one month incubating them. While some ducks, like common eiders, will stay on their nest nearly continuously, other ducks take more frequent breaks to eat. But even they will lose roughly 30 per cent of their body weight during incubation. In some cases, hens may abandon their clutch if conditions become unfavourable (bad weather, disturbance by humans or predators).

The blue-winged teal hen settles in, using her body to gently shield and warm her clutch of seven eggs.

And now, we wait…

While you’re waiting…learn more about the amazing egg.

Part 3: The Hatch

Shortly before hatching, the nearly developed blue-winged teal embryos produce clicking and peeping sounds inside the eggs. These vocalizations help synchronize hatching among different members of the brood. The hen responds by making soft clucking sounds to her unhatched ducklings. These early communications are a crucial part of a process known as imprinting, in which the ducklings learn to recognize their mother’s voice. This ensures that the brood will follow their mother when it’s time to leave the nest.

As the hatching process begins, each duckling penetrates the inner shell membrane of the air cell with its bill, and its lungs start to function. Next, the ducklings take on the arduous task of breaking out of their shells, a process known as “pipping.” They use an egg tooth—a hard, horny structure on the upper tip of the bill—to break through the outer shell membrane and shell.

It takes about a day for all the ducklings to hatch. Once their yellow, downy bodies emerge from the eggs, they remain in the nest with the hen for another 24 hours until their down has dried. Then, the ducklings leave the nest and follow their mother to a nearby wetland to feed. Ducklings are precocial offspring as opposed to altricial offspring that stay in the nest and are fed by the parents until fledging (e.g., American robin)

While you’re waiting, enjoy these adorable up-close photos of other duckling species.

Part 4: The First Week

The eggs have hatched, and the hen has led her ducklings safely lead her seven ducklings through the grass to her wetland. Finally, mom can focus on relaxing and refueling, right?  Not exactly. Instead, she’ll help her ducklings find food high in protein and calcium, required for muscle and skeletal development. While ducklings are precocial (mobile after hatching), they still need help to find suitable habitat and food. She will also shelter them with the warmth of her body at night and during adverse weather.

The blue-winged teal family share this wetland habitat with hundreds of other common wildlife and species at risk, including plants, insects, fish, turtles, snakes, birds and animals of all sizes. The hen keeps her youngsters close; teaching them to rest and forage among the stands of bulrush and cattail to avoid danger. Blue-winged teals are a dabbling duck species that eats at the water’s surface or by “tipping up” to get at submerged plants and prey. For most of the day, the family paddles around the wetland, dabbling to feed mostly on high-protein sources like insects.

Unfortunately, while searching for food, young ducks can become food themselves. One hapless duckling ventures too far from his mother’s watchful eye and is caught by a northern harrier that swept low over the wetland and picked him off the water’s edge as the hen caterwauled in distress. Another duckling falls victim to a prowling fox in the middle of the night. The hen does her best to be vigilant, but the odds are against her. On average, about six in every 10 blue-winged teal ducklings will die of exposure or killed by predators before they are old enough to fly.

Don’t let nature’s way discourage you. Stay tuned and watch your inbox for Part 5: On their own.

Part 5: On their own

After 35 days, the hen leaves her brood of five to prepare for moulting (the process in which ducks lose their flight feathers). The young ducks are now on their own, but their mom has taught them well and they are now able to source their own food. After a month of swimming, diving and chasing each other across the water, the ducklings are also bigger, faster and stronger—making them far more difficult for predators like foxes, raccoons, red-tailed hawks and mink to catch and eat.

For the young ducks to grow and develop in time for fall migration, their primary job is to eat, eat and eat. In addition to plants, they’ll feast on an energy-rich assortment of high-protein beetles, larvae, snails and aquatic invertebrates.

At this stage, they are fledging, or developing their flight feathers. Birds’ feathers are the human equivalent of hair. Feathers insulate birds’ bodies, attract potential mates, and provide an aerodynamic shape for flight.

The feat of flight requires a few different feather types. The most important are the ten long primary feathers. These are the wing feathers found furthest from the body. They’re attached by ligaments to what would be the “hand” bone—if ducks had hands. These are so essential to flight, domestic birds with “clipped wings” have had their primary feathers cut off to prevent them from flying. Primary feathers provide the thrust on the wing’s downbeat. They’re darker at the ends due to a high concentration of melanin—the same compound that gives human skin its colour—which makes the tips of these essential feathers resistant to wear.

Secondary feathers are shorter flight feathers that are anchored to the “forearm” bone, spread out next to the primaries. They make up the speculum, a flash of colour featured by many duck wings, which is an iridescent green in the blue-winged teal. On the wing’s upbeat, the primary feathers spread out to allow air passage, while the secondary feathers force air up from the wings, providing lift.

As they approach 50-60 days old, the young ducks will be taking short test flights in and around the wetland to build their strength for the biggest challenge of their young lives, just around the corner.

Eager to learn more feather facts as you await the next installment? Check out how researchers use feathers to learn more about waterfowl.

Part 6: Bidding farewell

Now fully fledged, the young blue-winged teal have joined other family groups in preparation for fall migration.

Since they are small ducks, they will be among the first to fly south when the weather turns cold. They’ll need the energy and fat stores they’ve built up during the summer to sustain them when they wing their way south to their wintering grounds. Up to 84 per cent of North America’s blue-winged teal population winters in Mexico. Some blue-winged teal, like those from Alberta and Manitoba, will migrate more than 6,000 kilometres to Venezuela or Peru.

En route, some ducks will stop to feed at wetlands along the Gulf Coast of Louisiana and Texas in the United States. Flooded fields of rice, a popular source of food and shelter, will lure others travelling along the Mississippi and Central Flyways. Some of them may encounter DUC’s 2021 Bonnycastle Fellowship for Wetland and Waterfowl Research recipient Brett Leach.  Leach, a MSc student at the University of Missouri, is conducting research on blue-winged teal migration and habitat use by marking the ducks with GPS/GSM transmitters. You can read more about Leach’s teal research in Louisiana’s rice fields here.

After several months basking on wetlands, estuaries and mangroves in their warm wintering areas, the teal will heed the urge to migrate northward. They, and millions like them, will return to their Canadian birthplaces, to locations deeply engrained in their memories.

Help us welcome the ducks back next spring, and the next…

It’s been an eventful several months since the blue-winged teal hen hatched her brood of ducklings and led them to the nearby wetland. In future years, these young ducks will return to this landscape to produce their own offspring and repeat the same fascinating but strenuous process.

Continuing that cycle depends on a key ingredient: abundant, healthy habitat. Good habitat across Canada’s waterfowl breeding grounds is essential to overcoming the many challenges of successful breeding, nesting and brood rearing. It’s the best welcome mat we can roll out for waterfowl every spring.

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