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.
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 46,000 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. Several factors may be contributing to this decline:
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).
The Common Loon
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.
Did You Know?
The 1988 fires affected 793,880 acres or 36 percent of the park. Five fires burned into the park that year from adjacent public lands. The largest, the North Fork Fire, started from a discarded cigarette. It burned more than 410,000 acres.