|Trumpeter Swans: Nesting Behaviors|
|Written by Chelsea Mohney|
|Friday, 21 June 2013 17:30|
The summer is bringing new hatchlings of all kinds to the Sanctuary! If you have recently visited, you will note that the goslings are growing and are no longer the cute fluffs of yellow that they used to be. We also have frequently seen two families of Mallard ducklings!
I am among those waiting, not so patiently, for them to hatch. My name is Chelsea, and I am the Summer Avian Care Intern here at the Bird Sanctuary. Although I have only been here for two weeks, I am enjoying every minute of working with the various bird species that take up residence at the Sanctuary. I am currently taking classes at Michigan State University to complete my undergraduate degree in Animal Science by spring 2014. After graduation I plan to enroll in Veterinary School and hopefully open my own practice one day. Before coming to the Sanctuary, I had little knowledge about birds and am finding that there is much to learn and skills to acquire!
One of the benefits of being the Avian Care Intern is that I get to live on site and that Wintergreen Lake is my backyard! Every night I am lulled to sleep and woken up every morning by the Trumpeter Swan’s trumpeting outside my window. At first this used to startle me, but now I can’t fall asleep without it. My mornings usually begin by taking a drive around the lake and other enclosures to check on the upland gamebirds, raptors, and waterfowl residents. Among them are several mated pairs of Trumpeter Swans.
Trumpeter Swans begin building their nests in late March to April. Their nests are usually made on an elevated mound near the shore of a lake or pond and can be made out of sticks, cattails, leaves, feathers, and other unusual items that the pair finds including string and wrappers. Once the nest is built, the female will often begin laying eggs once every other day until she produces a clutch of between four to six eggs. Before a clutch is established, the female will often leave the nest unattended to feed. When she does this, the eggs will be covered with nest material to hide them from hungry scavengers like raccoons.
If scavengers do not steal the eggs, they will hatch after 33 to 37 days of incubation. The swan hatchlings are called Cygnets and are born with their eyes open, able to swim, and feed on insects and vegetation. They will usually stay in their nest for approximately 24 hours before taking their first swim. Newborn Cygnets are the most susceptible to disease and such predators as the snapping turtle, fox, raccoon, and coyote because of their small size. The Trumpeter parents have also been known to drown their young due to illness or injury to avoid their suffering and the chance of it drawing in predators to the rest of the family. For these reasons, it is not uncommon for a pair to loose all or have only a few Cygnets survive to adulthood. Trumpeter swan pairs usually learn from experience over time and older pairs have better hatching and rearing success.
Pair of Trumpeter Swans nesting on the Lagoon shore
The average pair of Trumpeter Swans has a rearing success of three cygnets. This may seem relatively low when each pair of swans has a clutch of four to six eggs per nest, but it is close to the rearing success of other waterfowl including the invasive Mute Swan. This low success rate doesn’t seem to be affecting the population of Trumpeter Swans and they are continuing to grow in number. This may be due to the fact that if their first nesting fails, they tend to nest again as long as there is still enough time in the season for the young to grow and make it through the winter. Nesting failures can be due to predation, disease, or infertility. At the Sanctuary, we have witnessed the unfortunate event of nesting failures. There were three different pairs of Trumpeter Swans that attempted to nest at various locations on Wintergreen Lake. All of the nests, due to unknown reasons, have failed and we will not be having any cygnets this year. We are hoping for a more successful year next year. But do not worry; you can still come to the Sanctuary to visit the goslings and ducklings that you can find on Wintergreen Lake or on the small Lagoon as you walk down the first set of stairs!
For more information on Trumpeter Swans and their nesting behaviors check out these websites below: