Birds & Birding

Why are Yellowstone’s Swans Disappearing?

Yellowstone National Park officials carry trumpeter swans. © Doug Smith/National Park Service

In the early 1900s, when people were driving any birds with attractive plumage to extinction, a small group of trumpeter swans persisted, tucked away in a hidden corner of the U.S.

They had been killed off nearly everywhere else. Hunters wanted their meat. Women’s hat and clothing manufacturers wanted their striking white feathers.

But in Yellowstone National Park, the nearby Red Rock Lakes National Wildlife Refuge and surrounding region, about 70 birds remained. Now in a twist of ecological fate, what was once one of the last reservoirs of trumpeter swans in the lower 48 may blink out.

“I think it’s on one hand tragic and the other hand sad because you are losing a native species that used to do extremely well in Yellowstone,” says Doug Smith, senior wildlife biologist with Yellowstone National Park. “I get you can’t preserve vignettes of primitive nature forever because systems are constantly changing, but swans have been a vital part of the ecosystem.”

Smith has been tracking trumpeter swans in the Park since he was assigned the duty in 2008. They’re not his only charge – he was the lead biologist when grey wolves were reintroduced, he’s watched as grizzly bears have made a comeback, and he’s helped track epic elk migrations — but of the megafauna he studies and manages, the trumpeter swan is one of the most iconic, easiest to see and longest documented (records go back in the Park to 1917).

It’s also one of the most imperiled.

Only two breeding pairs exist in the Park now, and their finicky nature means many years they may simply choose not to reproduce, and they haven’t in the last two years.

“Right now, we’re not sure why swans are doing poorly,” Smith said. “We have some good ideas, but we can’t say it definitively. If we learn that Yellowstone has changed so much it’s no longer swan habitat, we have to bite the bullet and understand that.”

The Last Reserve

Like grizzly bears and bison, swans’ longevity in Yellowstone National Park was largely a product of its protected status. The Park was established in 1872 to protect its soaring geysers, psychedelic hot springs and complex thermal features. As a side effect, the wildlife in the park was also preserved.

John James Audubon’s print of a trumpeter swan.

Red Rock Lakes was set aside as a swan refuge in the 1930s, when officials realized it was one of the few remaining locations with the massive birds.

Once the country decided it was time to stop hunting swans and start protecting them – in the 1960s – about only a few thousand remained across the continent, according to the Trumpeter Swan Society. Outside of Yellowstone, Red Rock Lakes and a few other refuges, the rest lived in remote portions of Alaska and Canada.

Swans and their eggs were used to try to restore populations in the West as early as the late 1930s and 1940s. In the mid-1960s, reintroduction programs began in Minnesota, and by the 1980s and 1990s, they were being restored in earnest throughout portions of the Midwest and Rocky Mountains.

Some of the relocations have been successful, such as the Upper Green River area in southwest Wyoming which now has more than 25 breeding pairs of swans.

It’s considered an expansion area, a possible connection between Yellowstone at the farthest north, the Snake River population near Jackson, Wyoming and south to Green River, says Susan Patla, nongame biologist for the Wyoming Game and Fish Department.

But the Snake River population is still small – about nine breeding pairs – and faces competition for food from Canadian and Alaskan birds that come down to the warmer springs to winter.

“When you look at the total number of young, we had 43 young produced in the Green River compared to 14 in the Snake River,” Patla says. “If we didn’t have a range expansion program I would be much more worried about the Snake.”

About 60,000 swans exist throughout North America now, mostly centered in Alaska, the Rocky Mountains and the Midwest.

But back in Yellowstone, the place that kept the species alive, the birds are struggling.

“If you graph the swan population, each year it’s increasing or stable from ‘30s to the ‘60s,” Smith says. “In the ‘60s, the line starts to dip down and in the early ‘90s, it dips down steeper.”

Humans Predators and Climate Change

Why, exactly, swans in Yellowstone are suffering is largely open for debate among biologists. But most wildlife managers have narrowed it down to three likely suspects: eagle predation, human disturbance and climate change.

Yellowstone National Park tourists watch and photograph trumpeter swans. © Doug Smith/National Park Service

Eagle predation, which seems like the most natural impact on swans, is also a product of humans. Lake trout were illegally introduced into the Yellowstone ecosystem and eviscerated the native cutthroat population, meaning instead of feeding on thousands of cutthroats, eagles are targeting other food such as swan babies.

And their impact is exacerbated by human disturbance.

“People see the swans and walk to them and say, ‘Isn’t that cool, it’s a swan.’ The swans go ‘oh sh–,’ and they swim out into open water (away from protective cover on the shore) and the eagles dive bomb their young. I’ve seen it from the air.”

When a swan pair produces only two or three young every year, losing a portion takes a quick toll on the population.

The other main issue is climate change, which is creating colder, wetter springs and drier wetlands in the fall. Both of which kill swans.

“Almost their entire diet is submerged aquatic vegetation, not like geese that will also eat Kentucky blue grass,” says Patla. “A family of two to raise four cygnets to flight takes 3 to 5 tons of vegetation.”

As wetlands dry in the summer and fall, so does the food.

Variable weather in the spring also can kill cygnets.

“Our two territories have not had young either year because their Achilles heel, what they don’t like, are cool wet springs. We’ve had two cool wet springs in a row,” says Smith. “It seems counterintuitive: How do you have cool wet springs due to climate change and wetland reduction due to climate change, but we do. Once summer hits it doesn’t rain.”

A Case for Intervention

By 2010, only eight swans remained in Yellowstone, and Park Service officials had two options: supplement the population with more swans or let the species go.

“We intervened, and the reason we intervened is because until you can identify the direct cause, we don’t want to lose swans. And two, if the cause is human, we can intervene.”

Since the likely causes are eagle predation – which was ultimately a product of humans introducing lake trout – human disturbance and climate change, the Park Service felt like it could begin bringing swans in to supplement the population.

Trumpeter swans in flight. © U.S. Army Corps of Engineers

Now about 25 individuals live in the park, but there are still only two breeding pairs.

Service officials have closed access to one of the nesting sites throughout the summer to prevent human disturbance. Swans at the other site are more accustomed to people, Smith says, and eagles aren’t nesting nearby.

But now biologists like Smith wonder if the population can ever be sustained again without human intervention, which is another ethical dilemma.

“It’s relatively cheap, and so you could keep bringing swans in. But fundamentally, the National Park Service is about natural processes, about letting nature take care of itself, reducing the impacts of humans and letting those natural processes occur on their own. Artificially augmenting the swan population indefinitely goes against that philosophy. Look at wolves. We reintroduced them for two years and they’re on their own in perpetuity.”

Swans will likely persist in other parts of the country, say biologists like Patla. The Green River population in Wyoming has plateaued, but is still strong.

Whether or not they can continue to exist in Yellowstone is still a matter for debate. Smith and others will keep trying fixes like building floating nests to prevent them from being flooded, continue reducing human impacts and reintroduce birds – the Service just released eight swans in early September.

“We would enjoy Yellowstone less to lose this magnificent beautiful bird that was once so common. It would be a less interesting and enjoyable world, not to mention ecologically we would lose a key component of the ecosystem,” says Smith.

“Some would say you can’t keep everything the same forever, and good point, but we’re humans, and it’s up to us.”

Christine Peterson

Christine Peterson has spent the past five years writing about science, nature and the outdoors for the Casper Star-Tribune, Wyoming's statewide newspaper. When she isn't tracking wolves, watching sage grouse or trapping black-footed ferrets, she's chasing trout. More from Christine

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  1. So sad about the swans. My grandpa and I would spot them all the time while camping. He died last year of prostate cancer. I still think about him whenever I spot them with my children now. I’d like to think he’s watching over me from heaven (or hell, he was a terrible man lol). -Teni C.

  2. I wish people would understand that illegally introducing a species, even game fish, into an area where they didn’t exist before, is extremely disruptive and damaging to other species who do. Please STOP! If you want to fish a specific species, go to its habitat, don’t bring it to another! And this is true for all species!

    1. It’s not “people” who introduce a new species into an established environment…it’s supposedly educated and knowledgeable people that do this kind of dis-service, and still it happens, they never learn. Look at the Asian carp and the Great Lakes, another example.

  3. Thank you for educating the public and spreading the word on what humans are able to so to correct our past errors. Swans deserve our input to flourish. Yellowstone without them would diminish the ecosystem. Perhaps add signs to encourage visitors to allow swans their needed space and enjoy them from an appropriate distance.

  4. Thank you for this article. I had no idea this was happening, and its a sad and challenging question.


    Not really.

    If I understand right, the swans have been functionally extinct for quite some time. Even if you could somehow ‘restore’ the species to abundances that matter, the ecosystem is on different trajectory now- nobody can turn back the clock.

    There aren’t enough resources to help but a fraction of the species that do have a good chance for recovery. Why waste what little we have on nostalgia?

    The article makes clear that the biologists are thinking about these issues. I just hope that they are able to make wise choices- to do what they feel is right- without undue political pressure. I know that is a tough thing to hope for in YNP.

    1. One of the primary issues cited is eagle predation, a shift attributed to Lake trout, who “were illegally introduced into the Yellowstone ecosystem and eviscerated the native cutthroat population, meaning instead of feeding on thousands of cutthroats, eagles are targeting other food such as swan babies.”
      Because the issue appears to be largely caused by humans, intervention by humans is appropriate. There has also been an ongoing effort to remove the invasive Lake Trout to give Cutthroats a chance to flourish again, and to help restore the natural balance of this ecosystem. The case for pulling back the human footprint as much as possible and then letting nature be , is strong. The actions are warranted.

  6. How beautiful the Trumpeter Swan is……I know that what the Trimpeter Swan wants is shown in the picture shown by John James Audubon’s ……..
    butterflys . Perhaps you could stop the spraying of chemicals that kill the catapillers and your influx of butterflys will definitely increase.

  7. So sad. Swans are so beautiful; a symbol of so many things. (ie. “Swan Lake and the “ugly duckling transformation” Opera.

  8. How come Wolves are given so much credit fo “ changing the Yellowstone eco system “ but no mention of the Wolves eating the eggs from nests on the ground

    1. A wolf-hater is easy to spot. If you’re truly concerned about the balance of nature, don’t cherry-pick something that was natural before people mucked up the total ecosystem.

      A similar thing is going on in Oregon/Washington with sea lions eating salmon that people have messed around with too much. They now say shooting sea lions is justified to save salmon, but won’t dare blame it on human overpopulation.

  9. Hi Christine.
    Here in Uganda we a blessed with natural rivers and lakes, can these swarms live on our lakes. I work with civil society organization in some Islands on lake Victoria a fresh water sou race, may i ask authority to allocate me an Island for them to breed.
    Feel free contacting me for futher info.

  10. Wonderful article about the vanishing Swans of Yellowstone. I really enjoyed it.

    Thank you for publishing this information.

  11. This article says: “the National Park Service is about natural processes, about letting nature take care of itself” but after years of humans interfering in a bad way with swans, we owe them interference in a good way for a few years. We didn’t let nature take its course when people were killing swans for their feathers & putting the wrong kind of trout in the streams; why start now? Balance the scales first.




  13. Best of luck with the Swans. I love to watch them and their addition to nature is so important! We have visited Yellowstone three times- the last time was Sept 2017- which was incredible! It was a trip of a lifetime. Our wildlife sightings were
    Beyond belief! We have visited 37 of the National Parks of the U.S. and Yellowstone is our favorite. I wish
    You great success in your important

  14. This report is far beyond alarming. With all of the decisions our government has been and continue to make to destroy these and other wonderful animals. We know we can’t save everything but we can save many from extinction.

  15. thats sad to hear i hope that we can bring the swans back and stop the destruction of yellow stone park from the destructive nature of trump and his followers,

    maybe we can find a more secluded spot so that they arent disturbed by humans

  16. I live in the Mission Valley in Montana close to the National Wildlife Refuge. We have several breeding pairs of Trumpeter Swans living there. When I lived in Washington State, the migrating swans always stopped by the fields in the Mount Vernon area. They are a beautiful sight to behold

  17. I have a question about the photo at the start of the article: How do the people carrying the swans get the swans to cooperate? I was always told that swans were very aggressive, and if you got within bighting distance you would get bit! Have I been misinformed all these years, or is some other factor involved, such as the swans being tranquilized, or accustomed to those particular handlers?

  18. Well, it seems obvious to me, considering what has been observed by air, that it’s time to temporarily stop allowing tourists to observe them at close range. The swans have made a pretty clear statement about how they feel by quickly moving away from all the cameras, phones and two legged featherless creatures.
    Isn’t it worth trying ?
    Mary Curro
    Portsmouth, VA

  19. Please Try To Protect This Beautiful Species So They May Flourish In Yellowstone Once Again.
    Tell NO ONE Where They Are…
    All Foreign “Invaders”, To the Natural Habitat Of Yellowstone and Surrounding Area, Should Be Banned From Farming/Agriculture/Sheep and Cattle Raising …
    They Too, Are Causing The Demise Of Our Wildlife
    PLEASE Provide/Protect Habitat For All Wildlife To Thrive…..

  20. Thanks so much for such an informative article, you’ve done great research.
    One question I have is how were the lake trout (what specie is this?) introduced ?
    Do these lake trout feed on the cutthroat? I’m a believer in climate change, but it is odd that the cooler, wet springs (two years seems a small sample) and dryer summers are the cause for less breeding.
    Do the swans sense ahead of time there will be no food (due to dry wetlands)?
    Keep up the great work!

    1. Hi Ken,
      Thanks for your questions and glad you enjoyed the story. Lake trout (Salvelinus namaycush) were first noted in Yellowstone Lake in 1994. They have long believed to be an intentional but illegal introduction by someone with a bucket, although some recent sources call this to question. There are non-native lake trout in other area lakes, and some believe they could have been moved from one lake to another by predatory birds. Whatever the case, they have proliferated. You can read more detailed info on the lake trout introduction, how they have affected cutthroat and more here:

      As far as climactic impacts on the swans, I don’t have an immediate answer and have not seen any literature on this.

      Thanks again for your comment.

      Matt Miller
      Cool Green Science editor

  21. Thank you, thank you for writing about this issue.
    Thank you to those involved in sustaining this population — their concern and the action they are taking.

  22. Interesting article. I shared it with the 36k members of the Facebook group “Yellowstone Up close and personal”.

  23. Well, actually, since people are historically not natural to the area, except for originally ,small tribes of indigenous people, then by allowing tourists in the park, you have already intervened in the natural processes of nature. That being said,you might as well keep introducing more swans. Don’t beat yourself up over it. If not that, then close the park, not something I would want to have happen.

  24. Why do humans have to mess everything up??? Then it takes more humans to try and make it right!!! And who suffers, the animals and the environment…

  25. The more variables, the harder it is to solve a question. Testing each variable under controlled conditions in the laboratory of nature is very difficult. The answer to the question why the swans are not able to produce at a rate to sustain or increase its population may never be solved just as scientists have never explained the extinction of the wholly mammoth .

  26. This is so tragic. The trumpeters are magnificent. We do not have them here on the Saint Lawrence river as far as I know, but I have noticed a decline in the swans here. I began walking near a specific area 9 years ago where up to 30 swans gathered. Now I may see six. I’m hoping they moved to more hospitable waters, but your article worries me.

  27. Beautiful, heart wrenching narration of the acts that are impacting nature in many locations globally. Very concise with non-judgemental journalistic clarity! Much to do! Little time to decide what.

  28. What a wonderful article Christine Peterson wrote about Trumpeter Swans. I had no idea that their breeding was such a dilemma in Yellowstone. I’m very happy that so many educated Scientists, Park Rangers and others are keeping such a close eye on this problem with the swans which, as you say, are a very important part of our ecosystem. With important articles like this, more and more people will recognize this importance. Thank you for this wonderful, educational article.

  29. Trumpeter swans have really taken off in Minnesota where we have a lake cabin. There are pairs breeding on most every suitable site in the lakes around us (the Tamarac National Wildlife Refuge) and throughout northwestern Minnesota. There are also many bald eagles, so I am slightly perplexed why the eagles in Yellowstone would be a prevailing factor in the swans decline there. We have been so encouraged to see the swans return to Minnesota. They are beautiful, intriguing and wild. I hope they continue to flourish there, and that the trend reverses somehow in Yellowstone. Thank you for the article.

  30. Nice to hear what Doug is up to. He likely wouldn’t remember me, I was the Lead Guide for Yellowstone Ecosystem Studies’ coyote/wolf study under Bob. Hello to Doug, keep up the great work! What would YNP be without you?

    Christine, thank you for publishing this wonderful and powerful article. You educated people and if even one does something, it gives the swans a better chance.

    A comment: Yellowstone National Park does not leave nature to nature. They are currently involved in the continued rounding up, sterilization experiments, and slaughter of our last wild, free, genetically pure bison, the last in our nation who live in Yellowstone National Park and must migrate into and out of the park to survive. Anything you can do to save the last Yellowstone wild bison before they are completely exterminated by APHIS, Montana DOL and YNP? Please help them and write about them before they are gone forever. Just one disease, for example, could wipe them all out. Please don’t edit or delete this.

  31. Because of humans we are even destroying Yellowstone. I have never been there but want to go some day but it is very sad how different it will be than in the past. Beautiful animals have to stop disappearing in this ecosystem. Can’t something be done with the Lake trout. I heard because of them that eagles are killing a lot more than just the swans and that is very sad. If we can mess it up we have to be able to fix are mistake.

  32. I remember with sheer delight the trumpeting calls of the trumpeter swans flying in for a majestic landing on a nearby lake in Yellowstone. This experience was a precious gift of Nature. I applaud all those dedicated people working to save these beautiful birds from their demise. Thank you.

  33. I know from our experience here in Chincoteague National Wildlife refuge, that several of the
    rangers and others who work with wildlife have long learned that “Swans drive other birds out”
    and addle their eggs when they leave a nest, to keep them down to a pair – or at the most, two.

    Do you have someone who was trained that way who believed it was a ranger’s duty to ‘
    prevent swans from building up a presence? I know it took us 5 or 6 years to ever see a
    Swan again, after the staff “protected” other ducks and beast, and the Swans out of local existance.

    1. Hi Susan,
      Thanks for your comment. The swans that have been present on Chincoteague are mute swans, a non-native species that can damage wetland habitat and indeed drive off native species.

      There are 2 native swan species in North America. The trumpeter swan is endangered. Rangers have not harassed or damaged eggs of swans in Yellowstone.

      Matt Miller

  34. I’m broken-hearted to learn of the decline of Yellowstone’s Trumpeter swan. They have always been a peaceful and glorious sight in the Park. I hope some mehods to help them survive are taken soon. Thank you for your efforts!

  35. What about reducing the number of introduced fish and introducing the native fish back? Probably a complex tax if not impossible. I just thought I would ask.

  36. And yet in Maryland, it is my understanding that the state government powers that be determined that there were too many swans in the Chesapeake Bay area, and follow a policy of “addling” the eggs in nests to prevent them from hatching. Very sad human behavior.

    1. Hi Barbara,
      Thanks for your comment. The swans being controlled in the Chesapeake Bay are mute swans, a non-native species that can damage wetland habitat and chase off native waterfowl species. The species in Yellowstone is the trumpeter swan, an endangered, native species.

      Matt Miller

  37. I live in MN near Monticello, and if you need some swans the Monticello population has exploded over the last decade by a full 10 times. You should see the DNR and parks department with help. Also there is an show on called Queen&Country watch season 1 ep. 3 The Queen’s Possessions they talk about a duck virus that kills swans. Hope your swans come out better in the years to come.

  38. It would seem logical, if there is an opportunity for a wildlife biologist to come to Yellowstone to study
    the swans and help the Park staff evaluate the situation, which may have already been done. As pointed
    out, things change but if the introduced fish were eliminated from the lake, then maybe that would be
    a starting point, to stabilize the appropriate fish species that the swans prefer. Electroshock fishing has
    been used in our local parks to do fish counts, but I don’t know how practical that would be in a large
    lake. It might also be detrimental to other animals (turtles, amphibians, etc.) but might help. While I was
    at the University of Maryland, we found that something as basic a trees and wetland plants were very
    important to maintaining healthy trout streams in the area. In parks that is possible, but in housing developments, etc. , the precious land and water habitats for the state butterfly were destroyed by development. Restoring appropriate habitat is really difficult to do with all of the unknowns that
    contribute to the ecosystem. I vote for continuing to study and introduce swans as they are such a
    precious resource. While the other swan populations are holding steady or increasing slightly, it
    could be a problem that is going to affect them, too, in the future. The question is why Yellowstone and what is different in the other areas where the swans are doing “ok”.

  39. As a kid spending summers at the summer range for my grandmother’s herefords at Antelope Basin, one of the sights was the Trumpeter swan pair on the lake there. They built raised nests in the marsh but often neglected their eggs and seemed to be distracted parents when they did have young.

  40. Ten or twelve years ago, while backpacking the Ice Age Trail in Wisconsin, I was blessed to catch sight of a pair of trumpeter swans near a small remote lake. They were banded around their necks and they flew in beautiful syncranized loops calling out their loud sounds. It was unforgettable. Sure do hope this lovely species can survive.

  41. I have been an endangered species advocate for fifty years. It started with polar bears. Here’s my take on what in Star Trek might be termed a “violation of the prime directive”: If disappearance were due to a natural catastrophe (say, the enormous meteor that caused the extinction of dinosaurs in the late Cretaceous period), I would say, sadly, that nature simply runs her course and there’s not much we can do about it; if, however, the causes – virtually ALL of them – can be traced to human behavior and activity, damn the “prime directive” and do what is feasible, possible, and humanitarian to protect these majestic birds. Once upon a time there were fewer than 3,000 humpback whale roaming the oceans of the world; now, thanks to a good lot of us who never gave up, there are over 30,000! See what I mean?

  42. I’m from the UK and swans are such a common thing, I always thought since coming to the US, that swans weren’t native to this country. I’m shocked that because of human’s and their incessant need to consume that these beautiful creatures are on the fast track to extinction. I think by far, it’s incredibly sad that humans do the most damage. I think trying to continue to help these beautiful birds is what we need to do. Letting them die out is an outrage… It’s laziness and insanity. All species of life is a part of a greater chain. Separate, they are weak, combined, they are that much stronger. I wonder if there need to be areas set up, that are strictly prohibited to humans. In the Galapagos islands… it’s only open to the animals themselves and scientists. I wish more people understood that humans are the root of many of these extinctions. It’s up to us to stop all of this from happening.


  44. Keep trying with the swans, at least bringing in new stock gives them a chance.

  45. I wasn’t aware (until the Internet revealed it) that people still shoot these birds and consider it normal. Go on YouTube and you can easily find the “hunting” carnage, with redneck cover stories about how they “need” to be thinned.

    What a sick species man”kind” is.

  46. I noticed in one part of the country the swans were competing for food with snow geese and Canada Geese. Snow geese migrate in winter and return to their native parts later in the season but Canadian Geese for the most part stay year round and have become more of a nuisance bird then a welcome guest. The flocks of Canada Geese has to be reduced significantly to make a difference. In New Jersey alone the problem is such that lakes and parks are infested with them and their droppings kill vegetation, infect lakes and ponds to the point of being clogged with green slime. Something needs to be done but here in NJ, they are reluctant to have extended open season to hunt them. One mating pair can have up to 12 goslings now times that by 10,000. It doesn’t take long to be overrun with these problem birds.

  47. I live in North East CT, up here we had a pair of breeding swans that lived on the CT river. The swans bred last summer and the female hardly ever left the eggs, however, the male swan was very protective of his mate and the young, so of course, people fishing the river or just floating by in canoes/kayaks would come close to the nest and the male would defend his family. Well, needless to say, the male was killed for “attacking” a pair of teenagers that were taunting the birds. I don’t think that was right, nor do the folks that live on the river, or anyone else that heard of this story. My question is what will happen to the female? I thought swans had mates for life, will she find another mate.

  48. I think you/we should do whatever we can to save them. They are an asset in Yellowstone.