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Ospreys Migrating

10-15-18 osprey 014

Banding birds, and the retrieval of these bands, has provided valuable information on the movement of birds. Today we also have the benefit of satellite telemetry, in which a bird carries a tracking device and its location is calculated via satellites that orbit the Earth.  The following is just a sample of what this tracking technology has revealed about the migration of Ospreys.

There are significant differences in male and female timing of migration (females leave up to a month before males), distance traveled and overwintering locations.  There is strong fidelity to overwintering sites as well as to migration flyways.  Breeding pairs of Osprey do not migrate or overwinter together, and adults do not migrate with their offspring.  Ospreys rarely migrate at night over land but inevitably migrate at night when undertaking longer (more than 12 hours) water crossings.

Subtle insights into migratory behavior can be gained by the findings of satellite telemetry, as well.  Their first flight south by juvenile Ospreys is often largely over water. A majority of juveniles migrating over the Atlantic Ocean from Massachusetts to the Bahama Islands flew as many as 1,500 miles over a period of up to 58 hours. The fact that no adults or 2nd year birds took this route over water suggests that juvenile Ospreys learn the coastal migration route during their first trip north.

Overwintering habitat preferences have also been assessed.  Of 79 Ospreys tracked by satellite, 30.4% overwintered on coasts, 50.6% overwintered on rivers, and 19% overwintered on lakes or reservoirs, with differences based on both sex and region of origin.

These few facts don’t begin to exhaust the information gathered from banding and satellite telemetry on Ospreys, much less many other species. They just serve to illustrate how modern tracking technology compliments and increases the information formerly gathered by firsthand observation and banding.

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8 responses

  1. Llyn Ellison

    Fascinating information about ospreys. I learn so much from your posts, Mary, and appreciate you sharing your vast knowledge of the natural world. Thank you so much.

    October 15, 2018 at 8:21 am

  2. Alice Pratt

    I wonder why, in some species, males leave first ….

    Hummingbirds do this, and in others the female leaves first.

    October 15, 2018 at 8:42 am

    • Excellent question, Alice. I’ll see if I can find an answer for you!

      October 15, 2018 at 11:56 am

  3. Patricia D March

    Where were the juvenile birds hatched, then? Is the first year called “fledgling”, the 2nd juvenile? Have been watching too many explore cams

    October 15, 2018 at 9:26 am

    • Penny, the birds the post referred to as migrating along the East coast were born in the Northeast. I have mistakenly used “juvenile” and “immature” interchangeably. Not so, according to eBird:

      “When in doubt use ‘Immature’ for any bird that is not an adult. ‘Juvenile’ is more specific, describing a bird still in its juvenile plumage. This plumage is held only briefly for many songbirds (just a few weeks after leaving the nest) or up to a year for some larger birds like hawks.”

      October 15, 2018 at 12:01 pm

  4. Will Lange

    I used to wonder why there were no ospreys nesting in the Far North, where there are so many fish. Finally I realized that it’s because the lakes and rivers are frozen so much of the year, the poor fish-eaters wouldn’t have time to raise a brood before retreating south.

    October 15, 2018 at 10:02 am

  5. I didn’t realize their range didn’t include the Far North, Will. That’s really fascinating.

    October 15, 2018 at 11:57 am

  6. Jo


    Am I misunderstanding the math here… Is it possible that some of these birds flew more than 25 miles an hour, or more, for up to 58 hours?

    Also, if I’m understanding this, it suggests that the juvenile birds only do the coastal route once, because it was the only route they knew at the time, having done it once before. How do the juvenile Ospreys, when they become second-year Birds, learn the other route(s)?

    October 15, 2018 at 1:26 pm

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