YELLOWSTONE, Wyo. — Yellowstone National Park announced today, Nov. 16, that for the first time since 1966, four trumpeter swan cygnets fledged from Swan Lake. The cygnets hatched on Swan Lake about four months ago.
Of the four cygnets that were born on Swan Lake, one took a little longer to develop the ability to fly and was left behind when the lake started to freeze over. Sometimes when a cygnet is not able to fly before freeze-up in autumn, it will die. In this case, the weather warmed up and the lone cygnet was able to forage on their own in the lake. After about a week and a half, the family returned and reunited with the cygnet. The waiting paid off and the fourth cygnet was able to fly to find open water with the rest of the swans, says the park.
According to Yellowstone National Park, it takes only about 1.5 days for the newly born cygnets to leave the nest and follow their parents into the water to begin feeding. At first, they can only dabble and graze, then as time passes, they learn to forage and care for themselves while staying close together as a family group. About three to four months after a cygnets birth, they begin to fly making short trips around the area.
Nearly all Rocky Mountain trumpeter swans—including several thousand that migrate from Canada—winter in ice-free waters in the Greater Yellowstone Ecosystem, but only a portion of them remain in the park to breed.
The counting of trumpeter swans in Yellowstone National Park began in 1931. The population peaked at 72 in 1961, but the population began declining shortly after and dropped further after the Red Rock Lakes National Wildlife Refuge feeding program ended. Populations were also affected when winter ponds were drained in the park in the early 1990s, says the park.
According to park biologists, In 2019, biologists observed 27 trumpeter swans in Yellowstone, including 21 adults and 6 cygnets. Two pairs attempted to nest in the park, on Swan Lake and an unnamed pond west of Lilypad Lake in the Bechler region, and a third pair on Grebe Lake did not nest in 2019. A fourth pair attempted to nest on Junco Lake, outside the park’s southern boundary. Both nest attempts in the park were successful, hatching at least seven cygnets and fledging four. Park biologists also say they released four young trumpeter swans in 2019 in Hayden Valley on the Yellowstone River, near the confluence with Alum Creek. The goal is that the released swans will become bonded to their release locations and continue to return the following spring.
In total, the park has released 35 cygnets over a seven-year period. Although several individuals are frequently seen within the park boundaries during the breeding season, none of the released cygnets have nested within the park yet.
Swans typically take at least four years to reach sexual maturity. Biologists are hopeful these young birds may breed in the coming years.
According to Yellowstone National Park, other factors that contribute to the decline in trumpeter swan populations include predation, climate change, and human disturbance. Some examples provided by the park include reduced wetland areas due to long-term drought or warmer temperatures and community dynamics such as changes in bald eagle diets due to the limited availability of cutthroat trout in Yellowstone Lake. Scientific evidence suggests that “Yellowstone provides marginal conditions for nesting and acts as a sink for swans dispersing from more productive areas,” says the park.
Concern about the Greater Yellowstone Ecosystem population has resulted in cooperative efforts between state and federal agencies to monitor swan distribution and productivity. Across the region, federal agencies currently survey swans in September to estimate the resident swan population and the annual number of young cygnets produced.