• Steam rises off of the colorful Mammoth Hot Springs Terraces. Photo courtesy Jacob W. Frank


    National Park ID,MT,WY


Osprey in flight
Like many other birds of prey, osprey (Pandion haliaeetus) populations declined due to pesticide use in the mid-1900s. Populations rebounded during the latter part of the 1900s. The first study of osprey in Yellowstone National Park occurred in 1917 by M. P. Skinner, the park's first naturalist. It was not until 1987 that the Yellowstone National Park bird program began monitoring breeding osprey annually, although an extensive survey on reproduction, diet, and habitat was conducted during the 1970s. Since monitoring began, Yellowstone's population of osprey has been considered relatively stable. On average, 50% of nests succeed (produce eggs) each year, with each successful nest producing an average of one to two young. These statistics are slightly lower than expected for a stable and healthy population, and may be explained by the park's harsh environment. In a recent study, scientists found that declining nest success for osprey around Yellowstone Lake is due, in part, to the decline of cutthroat trout. Ospreys are surveyed via fixed-wing aircraft and by ground-based surveys from May through August. During the survey flights, the majority of nests are monitored for occupancy and breeding activity. In addition, all suitable lakes and rivers are surveyed for potential new territories and nest sites. Learn more...

Quick Facts about Osprey in Yellowstone
  • In 2013, 29 active nests were monitored, with 87% of them successful, greater than the 27-year average (51%) and the highest ever recorded.
  • Young produced per breeding pair averaged 1.54 in 2013, while the 27-year average was 0.84.
  • For the second year since 2007, osprey nests at Yellowstone Lake were successful (3 in 2013). Parkwide, osprey reproduction has increased each year since 2003.

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