Common Loon

Wetland Birds
Approximately 30 percent of bird species that breed in the park depend on wetlands. Scientists are concerned about these species because wetlands are expected to diminish as temperatures increase. They are monitoring the trumpeter swan, common loon, and colonial nesting species, such as the double-crested cormorant and American white pelican. Yellowstone has years of data about the rate and success of nesting for some of these species, but not enough information about changes in the timing of their nesting activity, which is an indicator of climate change.

The Common Loon
(Gavia immer): 

The park's loon population is one of the most southerly breeding populations in North America and one of the only populations breeding in Wyoming (It is also the largest loon population in Wyoming.) Since 1987, park scientists have collected data on common loon nesting.

Harlequin Duck
Histrionicus histrionicus

The Harlequin Duck population in Yellowstone NP continues to maintain itself and is only mildly variable from year to year, with generally 22–26 pair residing in the park. Monitoring adults is the most effective method of keeping track of population vigor and trends. Monitoring annual productivity is not cost effective, as data collection is extremely time-consuming and difficult due to the remoteness of many of the areas in which harlequins are found. Productivity is extremely variable from year to year and is highly influenced by weather, such as flooding.

Trumpeter Swan
Cygnus buccinator

This species is probably most imperiled in Yellowstone National Park. Longterm monitoring, research, and management continue. Trumpeter swans in North America neared extirpation in the early 1900s due to human encroachment, habitat destruction, and the commercial swan-skin trade. Small populations survived in isolated areas such as Yellowstone. Red Rock Lakes National Wildlife Refuge, west of the park, was set aside in the 1930s specifically for this species. In the 1950s, a sizeable population of swans was discovered in Alaska. Today, more than 20,000 trumpeters exist in North America. Their population in the Greater Yellowstone area (GYA) is considered stable, but the park's population is declining. In recent years, fewer than 10 swans have lived here year-round. Winter numbers vary from 60 to several hundred. Reproduction rates are low. Scientists suspect that several facts are contributing to this decline:

• loss of wetlands during an extended drought in the late 20th and early 21st centuries
• few trumpeter swans taking up residence in the park
• competition with swans that migrate to the park for winter
• increased predation by coyotes & wolves

Information on the GYA resident swan and winter swan populations dates back to 1931 and 1971, respectively. Federal agencies conduct two annual surveys: The February survey counts how many migrant swans winter in the region; the September survey estimates the resident swan population and annual number of young that fledge (leave the nest).

Raptors
More than a dozen raptor species can be seen in Yellowstone. Three-peregrine falcons, bald eagles, osprey-are carefully monitored. The falcon and eagle were formerly on the federal list of endangered and threatened species. Their monitoring is required by law. The fish-eating osprey is being monitored because it is especially vulnerable as the cutthroat trout declines in Yellowstone Lake.

Osprey
Pandion haliaetus

Like many other birds of prey, osprey populations declined due to pesticides in the mid-20th century. Its populations rebounded during the latter part of the 20th century. Monitored since the late 1980s, Yellowstone's population of osprey is considered relatively stable. On average, 50 percent of nests succeed (produce eggs) each year, with each successful nest producing an average of one young. These statistics are slightly lower than expected for a stable and healthy population, and may be explained by the park's harsh environment. As with bald eagles, scientists suspect that declining nest success for osprey around Yellowstone Lake is due, in part, to the decline of cutthroat trout. They are testing this hypothesis.

Peregrine Falcon
Falco peregrinus

In 1962, Rachel L. Carson sounded an alarm about the irresponsible use of pesticides with her landmark book, Silent Spring. Among the dangers she described were the adverse effects of chemicals-particularly DDT-on the reproductive capacity of some birds, especially predatory species such as the bald eagle and peregrine flacon. Her book raised public awareness of this issue, and was one of the catalysts leading to the United States banning the most damaging pesticides.

The peregrine falcon was among the birds most affected by the toxins. It was listed on the endangered species list. Yellowstone National Park was a site for peregrine reintroduction in the 1980s, which were discontinued when the peregrine population began increasing on its own. The falcon made a comeback in much of its former range, and was delisted in 1999. For 115 years after the delisting, the peregrine will be monitored closely, and scientists will watch for threats to their population.

Yellowstone's relatively pristine conditions and long-term monitoring of peregrines provides baseline information to compare against other U.S. populations. Continued monitoring is essential, not only for comparisons with other populations, but also because peregrine falcons and other raptors are reliable indicators of contaminants (such as PBDE-polybrominated diphenyl ether) and climate change. For example, to assess the levels of PBDE, scientists collect eggshell remains after peregrines have left their nests for the season.

Bald Eagle
Haliaeetus leucocephalus

Monitored since the 1980s, when the bald eagle was placed on the federal list of threatened species, Yellowstone's population of bald eagles is relatively stable. In 2007, it was removed from the federal threatened species list, and monitoring continues. Each year, 40 to 60 percent of nests succeed (produce eggs), with each successful nest producing an average of 1.42 eaglets. These statistics are slightly lower than expected for a stable and healthy population, and may be explained by the park's harsh environment, especially during the early breeding season (February-April), and the declining cutthroat trout population in Yellowstone Lake.

Finding Bald Eagles in Yellowstone
Where to Look:

Summer - Yellowstone Lake, Hayden Valley, Madison River.

Winter - Madison River, Gardner River, Hayden Valley.

One endangered bird species previously occurred in the greater Yellowstone area: the whooping crane.

The scientific name of the Whooping Crane Grus americana, literally translated means "American crane." While the Whooping Crane is endemic or native to North America, it is without question one of the most endangered and spectacular of the 15 species of cranes found in the world. The Whooping Crane is currently classified as an endangered species under provisions established by the Endangered Species Act of 1973 and administered by the U.S. Fish and Wildlife Service

Adult Whooping Cranes are easily identified by their strikingly bold white body plumage, black wingtips, black facial feather markings, red crown patch, black legs and feet, yellow-black bi-colored bill, and yellow eyes. The Whooping Crane is the tallest bird in North America, standing 5 feet tall, with a wingspan that measures 7 feet in length. In flight these birds are quite easy to identify with the bold black and white plumage, extended neck, and trailing legs. Males are slightly larger than females both in size (although difficult to judge) and weight ( males weigh 16 pounds and females 14 pounds).

Whooping Cranes get their name from their loud, distinctive "whooping" call emitted by the male or female or simultaneously by both members of a pair. Calling is a method of communication in cranes and is used to reinforce pair bonds, defend territories, detect danger, or consequently sound alarm.

Historically speaking, fossil evidence of Whooping Cranes in North America dates back several million years, and shows these birds once occurring in a large geographical area extending from central Canada to central Mexico, and from Utah to the Atlantic coast.

Information is sketchy as to whether or not Whooping Cranes ever nested in Yellowstone National Park. Whooping Crane numbers were probably never superabundant over the last 200 years, however there was still a sizeable North American population remaining up until the 1860's. By the 1890s the Whooping Crane was nearly extirpated from most of its range, with only two flocks remaining by 1939 - a relic non-migratory flock in southwestern Louisiana, and a migratory flock that nested in west central Canada and wintered in southeastern Texas.

The decline of the Whooping Crane in North America was primarily due to an expanding human population. In the late 1800s and early 1900's there was a rapid western expansion of the continent by pioneers and European settlers. Shooting played a major role in the decline of these birds, however agricultural practices such as tilling prairies and draining marshes also contributed to the decline. As these crane numbers plummeted, demand for rare species such as the Whooping Crane increased further through demand created by taxidermists, private and museum collectors, and hunters. By 1950, the entire Louisiana Whooping Crane population had totally disappeared. All that remained was a migratory wintering Texas population numbering about 15 individuals, yet the location of the nesting grounds remained unknown. In 1954, that mystery had been solved, when a helicopter crew returning from a wildfire discovered three Whooping Cranes in Wood Buffalo National Park. In 1955 Robert Porter Allen and Robert Stewart confirmed the location and discovered a Whooping Crane nest. The riddle had finally been solved and this marked a critical juncture in the conservation of the Whooping Crane.

The isolation of Wood Buffalo National Park coupled with creative captive propagation techniques played a critical role in bringing the Whooping Crane back from the brink of extinction. Biologists learned over time that Whooping Cranes which traditionally lay two eggs, only are successful in fledging one young. Therefore one egg was removed from wild nests and hatchlings from this experiment formed the basis for the captive flocks we find in existence today. In 1999, the North American Whooping Crane Population was estimated to be 183 birds in the wild, 99 birds in captivity, and 4 birds found in the Rocky Mountains classified as "experimental-nonessential".

Whooping Cranes in the Rocky Mountains

A cross-fostering experiment to create a new migratory flock of Whooping Cranes took place in the Rocky Mountains in 1975. Under the direction of the U.S. Fish and Wildlife Service and the Canadian Wildlife Service, researcher Rod Drewien transported Whooping Crane eggs from Wood Buffalo National Park in Canada and placed them under incubating Sandhill Cranes on Gray's Lake National Wildlife Refuge in Idaho. The main focus of the cross-fostering experiment was to have Sandhill Crane adults hatch and raise Whooping Crane young, thus leading immature Whooping Cranes on migration to a Sandhill Crane winter safe haven known as Bosque del Apache National Wildlife Refuge in New Mexico.

Initially, the cross-fostering experiment showed promising signs, but eventually problems began to develop. Of particular concern was high crane mortality, and Whooping Crane mating behavioral problems associated with the experiment. However, a significant amount of valuable information was gained as a result of this study. In summary, a total of 289 eggs were removed from the wild for this experiment, which resulted in the Rocky Mountain Whooping Crane population reaching a peak of 35 subadult/adults in 1985. In 1999, only two adults survived from the original Gray's Lake experiment, and resided within the Greater Yellowstone. These birds were not paired. One bird resided in a remote area of Yellowstone National Park for years, and the other frequented the Centennial Valley of Montana. On March 15, 2000, a significant event took place in the history of Yellowstone ornithology, when the lone whooping crane that had resided in Yellowstone National Park for years, died from a collision with power lines in the San Luis Valley of Colorado. Therefore, only one adult from the Gray's Lake experiment remains alive today. This bird frequents the Centennial Valley of Montana.

In addition, the Yellowstone National Park bird program has been monitoring a "sandhill-whooper" hybrid since it was discovered in 1992. The bird was frequently seen with a Sandhill Crane and was being carefully monitored. This bird had significant scientific value, since it allowed scientists an opportunity to determine whether it could reproduce successfully in the wild. This is an important piece of information could have assisted Whooping Crane recovery efforts in the future. However, the hybrid crane could not be located in Yellowstone National Park in 1999, and is presumed dead.

Another Whooping Crane "experiment" occurred in the Rocky Mountains in 1997/1998 that had a bearing on Yellowstone National Park. Four young Whooping Cranes raised in captivity at Patuxent Wildlife Research Center in Maryland, were transported to a ranch in eastern Idaho as part of an experiment to learn how to establish a new migratory flock of Whooping Cranes in North America. The birds were trained to follow an ultralight aircraft. In the autumn of 1997, these cranes traveled from eastern Idaho to Bosque del Apache NWR in New Mexico following the aircraft. Two of the cranes were killed by predators on the wintering grounds. The two remaining "ultralight"cranes began their spring travels north on March 5,1998, staging for a month in the San Luis Valley of Colorado. Once moving again, the birds started to have problems with fences and power lines. Collisions with wires continues to be the greatest cause of mortality for immature Whooping Cranes. Therefore, these cranes were quickly recaptured and released into a safer environment in Yellowstone National Park. In May1998, without little forewarning, two "ultralight" Whooping Cranes were released in the Slough Creek area of the park. This area where the cranes were released proved to be troublesome. Large numbers of visitors were coming in close contact with the birds creating further imprinting problems. Later that summer, an effort was made to recapture the cranes, but only one "ultralight" bird was caught and transported to a remote area of the park. The other crane remained in the vicinity of Slough Creek until it migrated that fall out of the area. Both birds returned to the wintering grounds in New Mexico. Then in the spring of 1999, one bird died in northern Utah from undetermined causes due to the condition of the carcass, leaving a lone survivor residing in eastern Idaho for the summer.

As it now stands, there are only two Whooping Cranes remaining in the Rocky Mountains. One adult from the Gray's Lake experiment, and one "ultralight" crane. The prognosis for the Whooping Crane in the Rocky Mountains does not look promising. Whooping Cranes are expected to disappear from the Greater Yellowstone landscape in the near future. The Whooping Crane Recovery Team has abandoned efforts to establish this species in the Greater Yellowstone and in the Rocky Mountains in the immediate future, citing mortality, disease, habitat, pair-bonding, and imprinting issues to name a few. In September 1999, the Whooping Crane Recovery Team recommended the Wisconsin-Florida corridor as the best experimental site for establishing a new migratory flock of Whooping Cranes. Experimental efforts will begin in the year 2000.

Sources:

• Yellowstone Bird Report 2006
• Cranes: Their Biology, Husbandry, and Conservation; Ecology,Status and Conservation by Curt Meine and George Archibald (Hancock House, Blaine,Wash..1996).
• International Crane Foundation Website at www.savingcranes.org

Field Checklist of Yellowstone Birds