Take a minute to imagine:

So you’re finally on vacation and have just arrived in the Pacific Rim National Park, on the West Coast of Vancouver Island. You get out onto the beach and smell the fresh salty air and hear the waves crashing around you. You spot a flock of sandpipers down at the north end of the beach, and you begin walk in that direction, in hopes of a closer look. It’s a long relaxing stroll, and the flock of sandpipers eventually move on before you reach them. As you walk down the beach you get lost in thought, combing the sand for cool shells to inspect.

You’re taken by surprise when you see a large, dark, shadow flit across the sand. Looking up you realize you’re about to catch a magnificent show as a hawk circles high over the water. It’s probably an osprey you think, due to the all-white body and covert feathers, and the dark wings, but growing up in the interior you’ve only ever seen them near freshwater. Once you hear its short, shrill whistle you know for sure what you are witnessing. Suddenly, it dives straight down towards the water, at an impressive speed, and just as it gets to the water’s surface, its feet plunge in, and out, in an instant. It flies away to its nest clutching a fair-sized fish, and leaves you with a feeling of promise for the good things to come during your stay in the park.

Hopefully you’ve all had the pleasure to witness such an event; whether you have or not, I recommend you read on about the fascinating life of the osprey, and then head to the nearest beach!

Key Characteristics of an Osprey

Size: Ospreys (latin name: Pandoin haliaetus) are large hawks, with a body around 0.6 metres long, (Sullivan, 2017), a wing span of 1.5 -1.8 metres and a typical weight ranging from 1.5 – 2 kg. This can vary though; as with most raptors, female ospreys are generally weigh 15 -20% more than males. Body size can also vary with location: ospreys in northern latitudes can be as much as 12 – 15 % larger than those living closer to the equator (Bierregaard et.al., 2016).

Diagnostic Features: (Bierregaard et.al., 2016)

Seen from below:

White body and primary coverts (the shoulders)

Dark wings, brown speckled with white

Distinctive thick black line through the eye

Yellow eyes

Wings bent at the shoulders

From above:

All dark brown

Dark on tail

White on top of the head

Small head compared to size of the body

 

Juveniles:

Browner feathers with pale edging

Underside of primary coverts have a reddish-buffy colour until their second molt occurs at age 2

Orange eye

Chicks:

Very fluffy!

Beware of Look-alikes:

If you haven’t identified an osprey by its shrill whistle (listen here), it is possible to confuse it with look-alikes also living near the water, such as the Greater Black-Backed Gull or a Bald Eagle (Bierregaard et.al., 2016).

As you can see, both the body and the wings are either fully dark or fully white in these birds, in contrast with the osprey’s dark wings and white body. In the juvenile bald eagle, there is is too much brown on the body and it does not share the characteristic deep shoulder bend of an osprey.

Diet: These raptors have a highly specialized diet and eat almost exclusively fish. In fact, research shows their diet to be 99% fish in most areas. They will often feed mainly on only a few types of fish, which vary regionally; in British Columbia, important ones include bullheads, carp, large-scale suckers, cutthroat trout, smelt, and surfperch (Bierregaard et.al., 2016).

Ospreys have several special adaptations allowing them to have a high success rate fishing. These include zygodactyl feet with a reversible outer toe that allows them to grab fish with 2 toes in front and 2 toes behind (2015, All About), they also have barbed foot pads which help them hang on to slippery fish, and an incredibly keen sense of vision, having been known to dive for a fish from a height of 40 metres! (Sullivan, 2017)

 

Distribution: Ospreys are found world-wide, always near water, both freshwater and marine, just as long as there are fish nearby!

Migration: Ospreys are seasonal migrators in most of their range, and often migrate alone. Ospreys banded in British Columbia usually leave in the fall, as late as early November and travel south to Mexico to the west coast or the Gulf, return in the winter in the spring as late as May. Hatch year ospreys usually leave later than their parents and may not migrate back north their first year (Bierregaard et.al., 2016).

Visit this site to check out research on osprey migration utilizing radio-transmitters: www.ospreytrax.com/OspreyMainPage.html

Nesting: Osprey nests are very cool and often conspicuous. Males can sometimes be seen breaking branches for females to arrange in the nest, and because successful osprey parents maintain nest site fidelity, they are improved upon annually causing them to reach sizes of over 3 metres high! They may be built high in trees near water, but are increasingly built on artificial structures, as natural habitat declines and waterfront developments continue. They are commonly seen on telephone poles, roofs, and even the tops of marine navigation buoys (Bierregaard et.al., 2016).

Ospreys are territorial and can often be seen fighting with other ospreys, bald eagles or gulls. They become sexually mature between 3 – 4 years of age and typically have a clutch size of 1 – 4 eggs per year.  Chicks fledge the nest when they are between 50 – 62 days old, and usually do not begin to successfully catch their own fish until more than a week after fledging. An unfortunate source of chick mortality occurs when plastic twine is used in nest building materials, and it gets wrapped around the chick’s leg, preventing them from fledging or severely injuring them (Bierregaard et.al., 2016).

To check out osprey nest locations or report a nest, visit: http://www.osprey-watch.org/nests

Conservation Status: Ospreys are often a poster child of conservation success. They are currently listed as an ICUN ‘species of least concern.’ This is a significant improvement, after experiencing severe declines in chick survival from the use of the pesticide, DDT. To learn more about how ospreys have made an amazing comeback, please check out my next blog: HOW OSPREYS GOT THEIR GROOVE BACK 

References: 

2015. All About Birds: Osprey. Cornell Lab of Ornithology, Ithaca, New York, USA. Retrieved from: https://www.allaboutbirds.org/guide/Osprey/ .

Bierregaard, R.O., Poole, A.F., Martell, M.S., Pyle, P., Patten, M.A. 2016. Osprey (Pandion haliaetus), version 2.0. In The Birds of North America (P.G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA. Retrieved from: https://doi.org/10.2173/bna.683 .

Sullivan, M. 2017. Facts about the Osprey. Published by Friends of the Osprey. Retrieved from: http://friendsoftheosprey.org/osprey-facts/ .