Last updated: August 27, 2026
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Trumpeting Preservation: Survey of Trumpeter Swans in Yellowstone National Park 1929-1933
Visitors to Yellowstone National Park may hear a resonant “honk, honk” sound echo around the park’s lakes. This is the call of the trumpeter swan (Cygnus buccinator).
The fate of this swan species was uncertain for decades. Hearing the birds today reflects nearly a century of conservation efforts by the National Park Service and other federal agencies, conservation groups, and dedicated individuals.
The National Park Service’s NPS History Collection includes field notes, photographs, and a recently rediscovered 1930 film publicizing the species’ plight. Together they present a unique history of the early efforts to learn about and protect the species.
NPS Photo
The Danger Line
Six feet long, weighing more than 25 pounds, and with a wingspan of up to eight feet, these large white birds live on quiet lakes and slow-moving rivers. They eat plants and insects.
Breeding pairs care for four to six eggs laid in June. Young swans, called cygnets, fledge in September. They pair up in the summer. Larger groups of trumpeter swans may be seen in winter.
By the early 1900s, hunting and habitat loss meant that the trumpeter swan was one of many species “reduced to the danger line by the pioneer depredations of man.” By the mid-1920s, a few pairs in Yellowstone National Park were the only ones known in the United States—and they were not successfully breeding. North America’s largest waterfowl species was in crisis.
NPS / Joseph S. Dixon / NPS History Collection, HFCA 1607
In 1929, George Meléndez Wright, Joseph S. Dixon, and Ben H. Thompson began a multiyear survey of wildlife in national parks. Their goal was to document wildlife conditions in western national parks and recommend ways to reduce the impact of human activity on the parks’ fauna.
Wright personally funded the endeavor until 1931 when Director Horace M. Albright became convinced of the value and need for the work. He made National Park Service funding available.
During the first year, the team observed two pairs of trumpeter swans in Yellowstone National Park, one at Alum Creek and another at an unnamed pond. Dixon wrote in his notebook that, “The large size of the swans together with their low-pitched sonorous bugle-like note proclaimed them Trumpeter swans without a doubt.”
Also in 1929, Dixon received a report that a pair on a small lake in the Lamar Valley failed to raise any young in the four or five summers they had been observed by park staff.
The team made plans to return to the park in 1930. That trip provided Dixon with the opportunity to document many previously unknown trumpeter swan behaviors including nesting, incubation and hatching, feeding, mating rituals, and defense.
NPS History Collection, HFCA 1645
NPS History Collection, HFCA 1607
Behind the Cameras: A Focus on Joseph S. Dixon
Wright, Dixon, and Thompson each took photographs during the wildlife surveys. Dixon, however, was an avid photographer and took the lion’s share of them. During the 1930 visit to Yellowstone, Dixon focused his lenses on the trumpeter swans.
Born in Kansas in 1884, Dixon grew up in California and went to university at Throop Polytechnic Institute, now Caltech, where he began studying biological fieldwork. His early expeditions with Caltech and then University of California, Berkeley, were to Alaska to collect specimens of seals, polar bears, and birds and to take field notes about wildlife.
On one of these expeditions in 1914, Dixon spent time accumulating over 1,000 specimens and over 200 pages of notes. He was over a year late for his own wedding when he eventually returned.
The National Park Service took over responsibility of the wildlife survey on July 1, 1933. It created a Wild Life Division with Wright as the division chief. Dixon and Thompson were named staff biologists.
Dixon became director and an instructor at the Yosemite School of Field Natural History (commonly referred to as the Yosemite Field School) in 1933 and taught there for nine years.
During this time, he also conducted wildlife surveys throughout the western United States., He focused in the areas of Sequoia and Kings Canyon National Parks from 1933 to 1937 and again in 1940 to 1942. During World War II, Dixon was one of three National Park Service biologists (with Adolph Murie and Victor Cahalane) who were allowed to remain focused on fieldwork. All others were transferred to other National Park Service activities considered crucial to the war effort.
Dixon retired from the National Park Service in March 1946. He spent his final years at his home in Escondido, California, where he passed away on June 23, 1952.
NPS History Collection, HFCA-01113
Journaling Nature: Understanding Dixon’s Survey
Throughout the National Park Service wildlife survey, Dixon kept detailed records about the animals, their behaviors and habitats, and human impacts he witnessed. Although scientific, his journal entries and images provide engaging insights into the trials and fates of a swan family at a time when the survival of the species hung in the balance.
Dixon often used symbols for female and male swans throughout his field notes. For simplicity, the symbols have been replaced with words in the excerpts used below. Punctuation has been added in places to increase the readability of the text. However, spelling has not been changed to retain the character of Dixon’s writing. Underlined text is Dixon’s original emphasis. Occasional clarifying text is placed in square brackets. Dixon used “(see photos)” to indicate which behaviors he photographed as well as described.
A Feathered Family
On June 8, 1930, the survey team returned to the lake where Dixon had found a pair of trumpeter swans the previous September. Their arrival was timely. A female was incubating her eggs in a nest and Dixon didn’t have long to wait. Dixon was well placed to observe their hatching and the parents early care, feeding, and defense of their young. Excerpts from Dixon's survey notes:
June 9, 1930: As I came over the sage-brush covered ridge half a mile from the lake I could see a large white bird partly hidden in a clump of dead tules. This proved to be one of the swans, believed to be the male, and a further search with the glasses revealed the other swan (female) sitting on a small haycock of dead tules that had been piled up in a dense growth of new tules.
At 7:58 this morning the female left the nest after covering the eggs carefully with dead and rotting tules. She swam directly away to the feeding grounds about 100 feet from the nest. As soon as she left the nest the male swam up and took up his waiting station withing 150 feet of the nest. However, when a raven came around the swan’s nest it was the female that spied him first and came flying and scooting in to drive the intruder away. It would appear that when the sun is well up that the female swan covers the eggs and leaves the nest to forage for her breakfast keeping a sharp lookout for intruders meanwhile.
NPS History Collection, HFCA-01113
The eggs hatched the next day.
June 10, 1930: This morning when we arose at 5:14 the female swan was on her nest. Between that time and 7:30 she was seen to move around slightly on the nest. I took up my place at an observation post behind a boulder about 150 yards from the nest at 7:48. Both swans were present, the female on the nest and the male went over on the end of the islet close by the nest and stood up in the sunshine in the open preening his feathers after he had circled swimming about the nest anxiously. This was the first time in two days that I had seen the male go ashore and preen.
At 8 o’clock the female reached her long neck over the side of the nest and dipped her bill into the water of the lake, then elevated her head and bill and swallowed the water. At 8:54 she again drank three times in 2 minutes by the watch while sitting on the nest.
At 8:20 the female reached her bill backward between her wing and body and probed around a bit apparently turning one of the eggs over with her bill. As she withdrew her bill there was some bit of white between her black mandibles. With the binoculars the bit of white appeared to be a large piece of eggshell. The mother again probed vigorously under her wing with her bill apparently helping to break the shell of the last egg because when she stood up a moment later I saw beneath her 4 downy white cygnets about the size of Teal ducks and one wet cygnet just out of the shell. Thus, the last egg hatched at exactly 8:20. (see photo).
The male swan staid within 50 feet of the nest, nearer than usual, while the eggs were hatching. A pair of coots and a pair of Pied-billed Grebes swam about and fed undisturbed within 40 feet of the swan’s nest, while a male Yellow-headed black bird perched and sang from the tip of a tule slightly above and within six feet of the mother swan and her newly hatched young.
Brood Care
Dixon continued to observe the newborns and their parents taking detailed—and at times poetic—notes about the dedicated parents and their vulnerable offspring.
June 10, 1930: At 9:20 the female swan stood up, fluffed her feathers and shook her body gently. The cygnets then squirmed and crawled about the nest in a reptilian manner with the body held prone sliding over the dead tules like a sea sled propelled by alternative strokes of the youngsters large but wobbly legs.
Between 8:20 and 9:20 the mother hovered her brood with her body prone on the nest and the cygnets tucked under her partly spread wings. At 9:20 she stood up giving the warm sun a chance to dry out the white fluffy down of the young. The cygnets continued to crawl about. One of the cygnets got directly under its mother’s breast where upon the mother took her bill and shoved the cygnet gently backward rolling him over and over out under her tail. She then continued to fluff and to tenderly preen the down of the cygnets with her huge black bill.
At 9:30 the male returned to the nest to inspect the young and then swam off fifty feet and started feeding.
From 10:45 to 12:35 the female brooded the young on her nest changing her position every half hour.
At 12:36 I am again at my watchpoint behind the granite boulder. As I watched with binoculars I saw two of the cygnets crawl out from under their mother’s half spread wings. After scrambling for about two minutes both youngsters tried to crawl up on their mother’s back, but they kept sliding off and were unable to make it. In the bright sun the downy cygnets appeared gray compared with the pure white of their mother.
At intervals all day today June 10, the day the eggs hatched, the mother swan kept arching her neck and shoveling out the inner wall of the nest so as to make a low wide platform for herself and young to stand on.
NPS History Collection, HFCA-01113
Like Swans to Water
Less than nine hours after hatching, the cygnets took their first swim. The excursion lasted less than six minutes.
June 10, 1930: At 4:57 when the clouds which had overcast the sky cleared away and the sun shone brightly the mother swan stood up and then slowly sat down and slid gently off the nest making a sort of a toboggan slide from the top of the nest into the water. She then turned around in the water and apparently called (I was too far—150 yards—away to hear a faint call) to the young. In any case they followed her lead, and all came scooting down the slide so fast that I could not count them.
At 4:59 all of the youngsters were floating about like downy white powder puffs in the water around their mother. They flitted and paddled about seemingly perfectly at home on their first excursion into the water. They dipped their tiny bills into the water and then raised their heads pointing their bills skyward evidently drinking the water. They fluffed out their downy wings and shook their little tails just as their mother did. While the cygnets were playing in the water their mother arose and climbed back upon the nest where she flapped her wings, shook her feathers thoroughly, stretched her legs for the first time today. The cygnets followed their mother’s lead and clambered slowly back up the slide onto the top of the nest. For the first time I got a distinct and satisfactory count (6). The mother dried them off with her bill and then covered them.
Dixon noted that after the swim, the mother reached over and built up the nest rim for the night with bits of old decayed tules. He stressed that “This is the first time I have ever seen a family of young wild birds of any species return to the nest for the night after once leaving it.”
NPS / Joseph S. Dixon / NPS History Collection, HFCA 1607
Parental Protection
Dixon’s notes observing the parent swans:
June 11, 1930: At 7:40 the young left the nest led by their mother and protected by their father who brought up the rear. They fed in the quiet shallow water for some time. At 8 o’clock I launched our portable rubber boat and rowed out into the lake. As soon as he saw me coming the male swan began to trumpet, a single loud resonant note “konk”, “konk”, “konk” repeated at intervals of about 3 or 5 seconds. He came out to meet the intruder but circled around to one side of the lake in an obvious effort to distract my attention from his downy youngsters.
When I approached the female in turn, she started off with four of the youngsters following her all strung out in single file keeping up as best they could with her. Two of the weaker cygnets took to the tules instead of following their mother into the open water of the lake.
One of the cygnets made good his escape into denser portions of the tules where I could not locate him although I could distinctly hear his plaintive low-pitched call note “screep, screep, screep” uttered at intervals of about 3 seconds and which could be heard a distance of 100 yards in the perfect quiet morning air. Even the voice of the day-old cygnet of the Trumpeter swan is characteristic, being lower pitched and more resonant than any other bird of this sort that I have encountered.
A Bird in the Hand
Separated from its mother, one newborn managed to get into mischief—with Dixon himself.
June 11, 1930: I followed the other young swan and caught up with him when he came across a patch of old floating dead tules which obstructed his way (see photos). However, the young cygnet soon clambered over the floating rushes and soon as he [could] get a good foothold in which operation his well-developed toenails assisted materially. At length this youngster in trying to dive upon my close approach became entangled in some old rotten tule stems so that I caught him which I would not have been able to do had he been in open water since they dive readily covering in a more nearly horizontal position. The cygnet waddled and swayed from side to side when he or it walked by in the water it made good speed straight ahead.
When I put this cygnet back into the water after warming and drying him in my cap he was more than anxious to adopt me as his guardian and often instead of trying to run away would come up to me and want to be hovered (at least he was content when I placed my cap over him or took him and held him in my hands). When I started to paddle away in the rubber boat the cygnet followed in my wake keeping close, within 6 feet of me, and calling cheerily as he swam.
When I stopped the boat, the cygnet stopped and began to search for food in the green scum of algae that we were in. Soon he spied an injured dragonfly, and he started after it pell-mell and caught it within a yard. The dragonfly proved to be too large to swallow whole, so he took it in his bill and banged it against an old dead floating tule. He then proceeded to gobble the fragments. After that he started after and caught other water insects so that the food of the young appears to be entirely insectivorous. When he got within 60 yards of his mother, he left me and went to her covering as much as six feet under water. They are expert swimmers and divers even at this early age of one day old.
NPS / Joseph S. Dixon / NPS History Collection, HFCA 1607
In hand, the day-old cygnet was about the size of a female green-winged Teal duck [about 12.5 to 15.5 inches long] but was much lighter in weight not being over four ounces according to my best judgement. At close range (6 ft.) the cygnet’s coat of soft fuzzy down was so fine that I could not focus except with difficulty on the individual barbules of the feathers. In the hand, when dry, the down was pure white not gray (which color was found to be due to the young being wet). The bill and feet were pale flesh color, while the tip of the bill and the toe nails had a slight olive yellowish cast. The eye was rich dark brown appearing black, but this was the only black on the day-old cygnet. On land in short grass (salt grass) the cygnet made good progress (see photos) traveling six feet in twenty seconds. At times the youngster stood erect neck extended vertically but most often it was held forward.
Family Dinners
Throughout his field notes, Dixon describes how the baby swans spent their days feeding, growing, sunning, and swimming while their nervous parents kept watch:
June 13, 1930: By 8 o’clock they were off the nest (father roosts beside the mother and cygnets now that the eggs are hatched) and the whole family was feeding together in the shallow water at the west end of the lake. By crawling up to within 100 yards and watching with binoculars I could see the parents thrust their heads down into the water and pull up the tender sprouting.
Often, they would raise their heads to look around for possible danger after diving and a white tule stem could be sometimes seen dangling from between their bills and reaching half-way down their necks. When a tule was pulled up, the young (part with the father and part clustered around their mother) would rush in to pick up the insect life and bite at the tule that would be scattered as the parents trashed the tules to pieces before they swallowed them.
Raven Mad
Other birds were a continual threat to the eggs and then the chicks after they hatched. Both parents steadfastly defended their young.
June 10, 1930: At 9:45 a raven flew by and circled about 50 feet above the nest inspecting it. Upon sighting the raven, the mother swan gathered her cygnets hurriedly under her wings and squatted upon them keeping them closely covered by slightly spreading her wings. No alarm note was uttered by either swan (as far as I could hear) but as soon as the raven appeared the male swan came rushing to the nest and staid close by and on guard (see photos) until 10 o’clock.
NPS / Joseph S. Dixon / NPS History Collection, HFCA 1607
At noon two pairs of ravens swooped down in football fashion upon the swan’s nest but both parents were there, and the ravens circled about over the nest several times then croaked and flew away. At 1:52 a single raven flew about 20 feet over the nest and the male swan rushed pell-mell back to the nest and remained there for 15 minutes after the raven left. At 2:31 two ravens came back and circled low over the nest and swooped down over the nest threateningly several times. The male swan again rushed to the defense of his home and the ravens flew away. At 4:02 pm an osprey circled over the swan’s nest calling several times. The female swan showed no decided anxiety, but the male swan rushed back to the nest from out in the lake in a hurry. Just then another raven came over to inspect the nest and the male swan staid around the nest for another 15 minutes.
June 12, 1930: This morning I awoke at daybreak 3:40 but the swans were still and quiet on their nest. At 5:10 two ravens made an attack on the swan’s islet but were repulsed. There was considerable trumpeting and loud alarm notes sounded by the swans when the ravens launched their attack. The male swan now sticks close to his mate and family of six downy cygnets rarely going more than 20 feet away from them.
June 13, 1930: This morning at 5 o’clock the father swan made a tremendous racket and trumpeted loudly and excitedly. By the time I got out of my sleeping bag and got my binoculars all that I could see to have caused the racket was a raven hovering over the swan’s nest where the mother swan was visible still sitting on the nest and covering her young.
Intruder Alert
Dixon and ravens were not the only intruders the parents had to worry about. Rival swans arrived threatening their territory and seemingly their pair bond.
June 12, 1930: This morning I awoke at daybreak 3:40 but the swans were still and quiet on their nest. At 5:10 two ravens made an attack on the swan’s islet but were repulsed. There was considerable trumpeting and loud alarm notes sounded by the swans when the ravens launched their attack. The male swan now sticks close to his mate and family of six down cygnets rarely going more than 20 feet away from them.
At 7:14 this morning I was startled by a series of loud trumpet-like calls from the swans and looked up in time to see another pair of adult swans come sailing into the lake from the west. The newcomers were quiet and lit in the end of the lake nearest camp away from the pair with young.
As soon as the new arrivals had quieted down the male swan began to trumpet again and for several minutes both parents faced each other and with bills close together went through a series of bowing and craning their necks together. At the height of this mating? performance the wings were half raised and a series of short resonant love notes were given. Every time the male started off toward the new pair of swans his female would start up the courtship again, evidently this being the way “she held her man”. This was repeated six times in 45 minutes.
NPS / Joseph S. Dixon / NPS History Collection, HFCA 1607
About one hour after the new pair of swans arrived the family male broke away from his mate and with a loud ringing battle cry few directly at the male of the strange pair. The strange swans saw and heard him coming and flew away and settled in another remote part of the pond. After this whenever the strange swans came within 200 yards, the family male would fly at them and drive them away. Once he caught the strange male off his guard and caught up with him flying directly into him and knocking him back into the water, hitting and striking him with his body and bill as he did so. After this episode the family female often left the downy young and joined her mate in his forays against the strangers. Having driven the strange swans away the parents flew back immediately to their young which kept in a compact flock in their absence.
At 10:20 the father and mother swan with six children went ashore on their little islet to sun and preen their feathers. Here on a bit of open ground covered with a dense growth of short green salt grass the cygnets stretched out their necks and laid down to rest on the grass in the warm sun while their parents finished their toilet and stood on one leg with their heads ducked back over their shoulder and bill under one wing.
June 12, 1930: Whenever the strange pair of swans came near the other pair the female with her characteristic foresight would begin at once to bow and court her mate always facing him so that their bills often nearly and sometimes did touch. This was done only when the strange pair of swans was near and when the family male had returned from a successful onslaught on the strange male (see movies). When thus engaged in courting behavior the wings of both birds were half raised and partly opened so that a very beautiful sight was presented. During the courtship the young were left to shift for themselves although they were usually close by.
At 11:40 the resident male swan few after the strange male and chased him completely around the lake twice. At one time they passed within 100 feet of me, and the swish of their heavy wings was distinctly audible. As they wheeled in turning their tremendous spread of white wings and bodies against the blue waters of the lake in which were reflected the passing wind-driven fluffy white clouds of the sky made a picture never to be forgotten. Just at noon both the male and the female resident swans took after the strange pair and drove them completely out of the region. It was plainly evident that they were both anxious to defend their home and home territory.
NPS / Joseph S. Dixon / NPS History Collection HFCA 1607
June 20, 1930: [The other swans] had no sooner struck the water than the resident pair or rather male began to call loudly and to advance towards them, threateningly. When he reached the point about 75 yards from the rival pair the male took wing and flew directly at the intruding male. The intruder took flight and was about 10 feet above the water when the resident male struck him in the center of the body with his breast, knocking him almost out so that he tumbled over and over and then both birds fell with a great splash into the lake where the battle was continued. The fight only lasted about seven minutes, both bill and wings being used. The strange pair they got up and took flight to the next lake half a mile up the river.
Although Dixon’s field notes reference movies that he shot of the swans conducting their mating ritual, that raw film footage has not been found.
NPS / Joseph S. Dixon / NPS History Collection, HFCA 1607
Muskrat Love
It was commonly believed that trumpeter swans make use of muskrat houses to create their nests. Dixon’s observations suggested that the swans did not treat muskrats as threats to their young and offered an alternative explanation for at least some of the swan nests.
June 17, 1930: Just a week after the swans hatched, I was photographing the nest in midafternoon and while waiting for the wind to lull, I saw the center of the swan nest start to hump up. I was only 15 feet distant so stood perfectly still in water over knee deep and in a few minutes the top of the nest just where the eggs had lain began to hump again and soon the back of the nest became faintly visible. This muskrat had evidently taken up and made his house in the swan’s nest as soon as they left.
NPS / Joseph S. Dixon / NPS History Collection, HFCA 1607
I examined the nest closely and it was clearly built by the swan, not an old muskrat nest and I suspect that in some reported instances where swans have nested on old muskrat houses that the tables may have been turned and the rat really took over the swan’s nest after the swans had hatched their eggs.
I have only found one real good muskrat house in the Trumpeter Lake, and it is out in the center of a shallow area that goes dry in September. Ben says he saw one other small rat house but all or nearly all of the rats live in burrows in the bank.
Dixon’s last photographs of the swan family were taken on June 30, 1930.
Roll the Tape
Dixon’s journal entries from June 14 and June 16 document that he took motion picture films of the swan family. His raw film footage from this 1930 field season had not been found.
However, an uncataloged 16mm with the unassuming label “Trumpeter Swans” was stored in a freezer in the NPS History Collection. Archivists thought it was probably a later visitor center film on the species, but considered if it could possibly be from the 1930 wildlife survey.
Opening the can, the film’s fragile condition stalled further handling. Rather than risking damaging it, the film was sent for professional digitization.
The NPS History Collection archivists held their breaths as they opened the digital file. It wasn’t Dixon’s raw footage. However, it was a sixteen-minute silent film titled “Trumpeter Swans on their Breeding Grounds.” The title card attributes the film to the National Park Service wildlife survey conducted by Wright, Dixon, and Thompson. This film, created with Dixon’s footage, is the earliest known motion picture film of the species.
Newspaper accounts document that Dixon presented lectures to civic groups which included “motion pictures of the trumpeter swans that inhabit Yellowstone Lake.” It seems likely that Trumpeter Swans on their Breeding Grounds was that film.
Descriptive Transcript
Title card reads: TRUMPETER SWANS ON THEIR BREEDING GROUNDS, Animal Surveys, U.S. National Park Service, Joseph S. Dixon, George M. Wright, Ben H. Thompson, Photography by Joseph S. Dixon.
Intertitle card reads: The Trumpeter Swan ~ The largest living native North American waterfowl, believed by many ornithologists to be on the verge of extermination in the United States, still struggles for existence in Yellowstone National Park where a few pairs have recently been found nesting.
A cloudy sky looms over a still lake and the small mountains behind it.
A different angle of the same lake and mountains, now with reeds and grasses visible in the lake.
A pair of adult swans swim on the lake’s waves, moving away from the camera.
An adult swan and baby swans, called cygnets, swim in the distance, close to a shoreline opposite from the camera.
Close-up of an adult swan swimming, with five baby swans swimming huddled up alongside the adult’s right side.
Two adult swans swim on a wavy lake, with reeds and tule grasses in the foreground.
Close-up of two baby swans swimming among the reeds. One swan chases the other swan deeper into the reeds.
Baby swan swims in the shallows among broken reeds. It swims away toward more open water.
Baby swan wiggles in the shallows among broken reeds moving towards open water.
Baby swan sits in thick algae in the shallows of the lake.
Baby swan waddles in the grass on land.
Baby swan briskly swims through the algae in the shallows.
Baby swan swims in calm water among a few short, broken reeds, opening its bill as if calling to others.
Wider-angle view of a baby swan swimming in algae-covered water. Reeds and grasses blowing in the wind and forested hills are visible in the background.
An adult swan swims on the open lake.
The swan family—two adults and five babies—swim on the open lake. Another bird, resembling a black duck, swims in the foreground.
An adult swan swims in from right to left, trailed by four of the babies.
An adult swan swims with six baby swans in front of her, close to her side. The babies spread out from the adult swan for a moment before returning to the their parent.
An adult swan swims out of frame, with three babies trailing behind. Another adult swan followed by three babies swim behind them.
An adult swan swims from right to left with three babies trailing behind.
An adult swan swims with five babies in tow. A sixth baby joins them.
An adult swan swims on a calm lake with one baby behind it. Behind the first group is another adult swan with other babies.
Now going from left to right, an adult swan swims with four babies behind it. Behind the first group is another adult swan with two babies.
An adult swan swims surrounded by six babies. The adult makes occasional honking gestures and looks around as the babies swim further away from her.
A wood stork stands with its feet in the water, with a tall grassy hill behind it. The stork moves around in the shallow water with its head down, eventually putting its beak down into the water to feed.
One adult swan swims on a wavy lake and is joined by a second adult. The second swan puts its head in the water for a moment.
The pair of adult swans swim close to the shoreline.
The swan family swims in the distance on the lake. Another lone adult swan swims closer in the foreground. The two adult swans turn their heads toward the intruder.
An adult swan swims on a calm lake.
An adult swan flies in with its wings spread open and lands on the lake.
Two adult swans swim on the lake facing each other and flapping their wings vigorously in defense before tucking them away.
An adult swan flies in low and lands on the lake in front of a group of baby swans.
The pair of swans swim on choppy lake. They briefly flap their wings and bob their heads up and down at each other in a courtship ritual.
An adult swan with its wings flapping swims quickly toward another adult swan and a group of baby swans. The adult that swam over bobs its head up and down and shakes its tail feathers.
One baby swan followed by its five siblings swims on the lake.
The swan family swim on a calm lake with five babies in a line between the adults.
An adult swan swims with three baby swans away from a rocky and grassy shoreline toward another adult swan in open water.
Two adult swans and six baby swans swim on calm water. The baby swans swim a little bit away from their parents—in different formations and in small circles—but never too far away.
A cloudy sky hangs over the swan’s silhouetted lake and the surrounding mountains.
End card reads: The End.
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- Duration:
- 16 minutes, 8 seconds
Watch a historical short film from the 1930s created to bring attention to trumpeter swan conservation in national parks. Footage is from a wildlife survey in Yellowstone National Park conducted by George Meléndez Wright, Joseph S. Dixon, and Ben H. Thompson from 1929 to 1933.
A Grave Concern
Dixon’s field notes and images are works of scientific observation. The Trumpeter Swans on their Breeding Grounds film was created to publicize the plight of the trumpeter swans. An intertitle card in the silent film notes that they are “on the verge of extermination in the United States, still struggl[ing] for existence in Yellowstone National Park.”
The fate of the swan family Dixon documented further demonstrates why the film was necessary. Despite the swan parents’ best efforts to care for and defend their six babies, by autumn 1930 only one survived.
Ranger Ben Arnold and Ranger-Naturalist Marguerite (Peg) Lindsley Arnold monitored the family after the survey team left Yellowstone National Park. They reported seeing the cygnets disappear one by one beginning in mid-August. Careful investigations could not reveal the cause, although it was noted that a family of otters had eaten several young ducks and mudhens in the area and may have also gotten the cygnets.
Dixon recorded in his notebook:
Mr. Arnold reports that the two adults and one cygnet were still on the lake on September 29, 1930, that the old birds were apparently trying to leave the country but that the young swan either could not or would not fly. The parent swans were very talkative and persuasive.
Despite its parents’ appeals, the last cygnet remained at the lake and almost certainly perished.
NPS Image
Trumpeter Swan Recovery
Low reproduction and survival rates, shrinking lakes which made swan nests more vulnerable to land predators, competition for food, human disturbance, and other factors continued to take their toll on the species. The National Park Service, US Fish and Wildlife Service, and other conservation organizations took up the trumpeter swan cause to prevent catastrophe. The small population of about 70 birds that survived in the greater Yellowstone ecosystem in 1930 provided the basis for widespread recovery in the 20th century.
Bird counts for the species began at Yellowstone National Park in 1931. The swan population recovered in the 1960s after intensive management. As a result of conservation measures, populations across the continental United States began increasing. As of 2015, there were approximately 63,000 trumpeter swans in North America belonging to three distinct subpopulations: the Pacific, the Rocky Mountain, and the Interior.
In 1961, the Yellowstone National Park population peaked at 72 resident swans. In 2023, rangers observed only 29 swans, including five breeding pairs.
The swans remain a species of concern in the park. Although the population has declined in Yellowstone National Park, it is stable within the greater Yellowstone ecosystem and increasing in the Rocky Mountains.
Learn more about trumpeter swans at Yellowstone National Park.
Sources
--. 1931, August 20. “The Trumpeter Swan Faces Extinction Despite Protections Given It by Law.” The Kansas City Star (Kansas City, Missouri), pg. 22.
--. 1932, April 15. “Joseph Dixon to Talk.” Evening Star (Washington, DC), pg. 29.
National Park Service. 2025, April 18. “Trumpeter Swan.” Accessed January 29, 2026, at https://www.nps.gov/yell/learn/nature/trumpeter-swan.htm
NPS History Collection. 2025, May 27. Guide to the NPS Wildlife Division Photo Cards. https://www.nps.gov/articles/000/guide-to-nps-wildlife-division-photos.htm
Shafer, C. L. (2001). “Conservation Biology Trailblazers: George Wright, Ben Thompson, and Joseph Dixon.” Conservation Biology, 15(2), pp. 332–344. http://www.jstor.org/stable/2641831
Wright, G.M., Dixon, J.S., and Thompson, B.H. 1933. Fauna of the National Parks of the United States: A Preliminary Survey of Faunal Relations in National Parks. Fauna of the National Parks of the United States Series. No. 1. National Park Service. Washington, DC. https://irma.nps.gov/DataStore/Reference/Profile/97220
Yosemite National Park. 2012. Joseph S. Dixon Collection Finding Aid. https://oac.cdlib.org/findaid/static/ark:/13030/c80c5186