FAQs • Pitkin County, CO • CivicEngage

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Osprey FAQs

1. What do Ospreys eat?: Ospreys are one of the few raptor species known to eat a diet almost exclusively of fish, often performing a shallow dive to catch them. For this reason, Ospreys nest in close proximity to shallow waters, including lakes, rivers, reservoirs, swamps and marshlands.

2. Do Ospreys migrate? If so, where do they go?: Ospreys are extremely long-distance migrants that breed in North America and migrate to Central and South America each winter. An Osprey may travel more than 160,000 migration miles during its lifetime. During a mere 13 days in 2008, one Osprey flew 2,700 miles - from Martha's Vineyard, Massachusetts, to French Guiana, South America (Cornell Lab of Ornithology)

3. Are Ospreys endangered?: Ospreys are listed as a species of “Least Concern” by the International Union for Conservation of Nature and are now considered one of the quintessential success stories of the conservation movement. Osprey population numbers crashed in the 1960s and ‘70s, when pesticides like DDT bio-accumulated in individual birds and thinned their eggshells, causing startling rates of mortality. Along certain portions of the Eastern U.S. coast, for example, nearly 90 percent of breeding pairs suddenly disappeared. The species' dramatic decline was halted by pesticide bans throughout the U.S. and the construction of artificial nests in wetlands countrywide. Overall, according to the North American Breeding Bird Survey, their populations grew by 2.5 percent per year from 1966 to 2014.

4. Do Ospreys mate for life?: Yes! However, when Ospreys migrate, they migrate as individuals. Rarely do both the male and female of a mating pair spend their winter in the same place. When the Ospreys migrate north for the spring breeding season, they each find their way back to the same nest.

6. When will Ospreys lay their eggs?: In Colorado, a female will usually lay her eggs in mid-to-late April.

7. How many eggs does a female Osprey lay in a season?: Typically, an Osprey female will lay two to four eggs during the breeding season.

8. How long do Osprey eggs need to be incubated?: Incubation lasts 36 to 42 days before the eggs hatch. The female will spend most of this time on the nest keeping the eggs warm during incubation, with the male taking over occasionally. The eggs will then hatch within a few days of each other.

9. How long does it take for Osprey hatchlings to fledge (leave the nest)?: Hatchlings will stay in the nest for 50 to 55 days before fledging.

10. Do the Osprey chicks compete with one another?: Sometimes. Osprey eggs are laid a few days apart from each other, and the oldest eggs hatch first. The chicks grow quickly, meaning that the youngest chick can weigh 25 to 30 percent less than the oldest chick by the time it hatches. When food is scarce, the older chicks may peck at or push the younger chicks to get the food they need to survive. Although this may seem harsh to humans, it makes it possible for the Ospreys to have one or two strong offspring rather than three or four weak offspring that may not survive. When food is abundant, this competition is not necessary, and the Ospreys may raise up to four healthy chicks.

11. What are some of the natural dangers to Osprey chicks?: Food scarcity can lead to competition among the chicks in the nest, and predators such as owls and raccoons may raid the nest while the parent Ospreys are out fishing.