The Osprey (Pandion haliaetus) is the sole member of the Pandionidae family and is amongst the best-studied birds of prey. A powerful, stocky bird that is flexible regarding habitat, the Osprey is found throughout much of the world and has a highly specialised diet. So, what do Ospreys eat?
Ospreys are expert fishers and have a piscivorous diet of 99% fish. Ospreys have several specific adaptations that help them catch fish, including a reversible toe and barbed pads on the feet. They hunt a vast variety of species of fish - over 80 in North America!
Very rarely, Ospreys catch lizards, amphibians, other birds and small mammals, which make up the remaining 1% of their diet, but they are highly adapted for catching fish. In the UK, there is practically no evidence of Ospreys hunting anything other than fish.
Ospreys are expert fishers
Indeed, the sight of an Osprey hunting its quarry is an impressive sight as they’re highly efficient and rarely make errors. Their specialised diet also helps ensure that they rarely compete with other raptors for food.
Ospreys have captured our imagination for thousands of years and feature in many ancient Roman and Chinese writings and religious scriptures. They’re also the namesake of several sports teams, including a Welsh rugby team, the Ospreys, and the Seattle Seahawks, an American football team.
Read on to learn more about this spectacular bird's diet and hunting behaviours!
An osprey perched, eating a fish
Ospreys eat a wide array of fish, and their diet varies hugely depending on where they are in the world and what sort of water sources are available nearby. Overall, Ospreys preferably target medium-sized fish that are around 15 to 35 cm in length and weigh 100 to 300g on average.
However, Ospreys have been observed carrying massive fish that likely weigh over 1kg!
Ospreys can dive to a depth of around 1m, which means they can only really hunt fish from close to the surface of the water.
In North America, Osprey diets include some 80 species of fish. In freshwater habitats such as Michigan, California and the Pacific Northwest, over 30 species of fish commonly feature in their diet. Major food items include herring, flounder, carp, sunfish, bass, sucker, bullhead, whitefish and salmon. Diets vary by region; in Washington, Ospreys eat primarily salmon, carps and minnows, whereas, in Massachusetts, Ospreys eat mostly herring. In Yellowstone, Wyoming and Montana, Ospreys feed primarily on trout.
In the UK, Ospreys most eat trout, pike, salmon, trout, flounder, mullet and perch. Their diets vary depending on whether they’re hunting at sea or in freshwater. However, Ospreys don’t specialise in one particular aquatic environment - they are generalists and are capable of hunting fish from practically any aquatic environment, including rivers, lakes, off-shore, estuaries, reservoirs, etc.
Ospreys may hunt between 3 and 5 different species at each feeding site. They’re happy to roam between feeding sites if necessary.
Ospreys migrate, so their diets change depending on where they are. As flexible but expert hunters, Ospreys are great at adapting their hunting skills to the climate, environment, and prey.
Wild Osprey (Pandion haliaetus) fishing in Rothiemurchus, Highland, Scotland
Adult Ospreys typically eat around 300g (10 oz) of food a day, typically between 1 to 4 fish.
When only smaller fish are obtainable, the Osprey might eat as many as 10 to 20 fish in one day. Many dives result in the catch of several small fish.
If possible, Ospreys will attempt to land their entire day’s food in one catch and then carry their food with them throughout the day if they cannot eat it all in one go. If they catch a big fish (500g+ is very possible), then they might not even be able to eat the whole fish. Ospreys are known to discard any fish that they can’t eat.
Studies show that Ospreys don’t cache food, meaning they don’t store their food in a safe place and return to it later.
Ospreys are also known as the sea hawk, river hawk, and fish hawk
Ospreys eat a tiny percentage of voles, birds, snakes, squirrels and muskrats (which make up around just 1% of their diet).
In rare cases, Ospreys have been sighted dropping conch shells from height and eating the molluscs inside.
It’s thought that particularly bad weather encourages Ospreys to turn their attention to other food sources besides fish. In the UK, there are practically no sightings of Ospreys eating anything other than fish in the UK. However, in Africa, after migration, Ospreys are sometimes sighted eating small animals and lizards until they settle into their feeding grounds. Rock iguanas are one of the most common non-fish prey of Ospreys.
There have also been isolated observations of Ospreys eating carrion from dead fish and even land mammals such as deer, but again, this is exceptionally rare or anomalous.
Osprey perched on the branch of a tree
Ospreys very rarely eat other birds. While there is observational evidence of this happening, it’s so rare that there’s no real account of what specific birds Ospreys target.
Ospreys may look to diversify their diet if they’re really struggling to find fish (e.g. their feeding grounds are still frozen when they return from migration).
Ospreys hunt by swooping across the water at high speeds, hooking and gripping fish with their talons.
While hunting, Ospreys typically hover and flap at the height of around 10 to 40m over open, in-land water, but at sea, they can ascend to heights of over 200m to catch sight of schools of fish. They also hunt from tree-top perches, particularly if they’re feeding from the edge of a lake or the lower course of a river.
Osprey vision is well-adapted for sighting fish that lie just under the top of the water - their eyesight is around 5 to 6 times more acute than a human’s.
After an Osprey sights a valid target, it will align itself into an attack position and rapidly descend towards the water at speeds of up to 80 miles per hour (128 km/h). Ospreys plunge into water foot-first and can dive to depths of around 1m if necessary. They will adjust their angle of attack depending on the conditions and the size and speed of the fish.
An osprey hunting for fish
Ospreys have several specific adaptations that help them hunt fish:
By pointing two toes to the front and two to the rear, Ospreys can easily grasp the barrel-shaped form of a fish. This is a rare and unusual adaptation called zygodactyly.
Amongst flighted birds (so excluding penguins), Ospreys are probably the most well-adapted raptors for hunting fish. While other raptors also hunt fish, such as sea eagles, they don’t possess the same level of diet-specific adaptations as Ospreys do.
Osprey diving for fish
Ospreys are carnivores, but they’re best described as piscivorous. Piscivores are carnivorous animals that feed solely on fish.
While Ospreys do eat other animals, fish makes up at least 99% of their diet. In fact, it’s likely that many Ospreys will never taste the meat of any other animal apart from fish!
Ospreys attempt to conserve energy where possible and only make as many dives as they need to ensure they’re well-fed, while also accounting for feeding any chicks where applicable.
Ospreys can quite easily catch their whole day’s feed in one go. Dives are successful up to 75% of the time, so Ospreys don’t need to dive many times a day to catch enough food.
An osprey flying off with a Kokanee Salmon, Hayden Lake, North Idaho
Baby Ospreys eat food delivered to them by their parents. Like their parents, their diet almost wholly includes fish.
Typically, the male brings food to the nest for the female to prepare, tear up and distribute amongst the chicks. Sometimes, the female will also hunt. Parental feeding continues from the breeding season until winter migration and may continue for 10 to 20 days into migration.
An Osprey feeding chicks fish in the nest
Ospreys are great users of artificial nesting platforms, which is a great way to attract Ospreys (and other birds of prey too). You’ll also need to be within around 1km of a fairly large, open water source; ideally a lake or a river estuary.
Nesting platforms are enclosed platforms positioned 10 to 30ft above the ground and are often designed with forks to somewhat resemble the forks of a tree. You can actually find plans for building Osprey nest platforms online.
The only way to feed Ospreys is by offering them a valid feeding ground in the form of a lake or a large pond. Ospreys are expert hunters and won’t eat food provided to them by humans (unless in captivity).
Osprey eating a fish, whilst perched in a tree
Ospreys are almost guaranteed to get all their water requirements from eating fish.
As raptors, Ospreys don’t use bird feeders. Instead, they’re expert fishers who almost solely dine on fresh, juicy fishes. No seeds, fruits or nuts here!
Osprey hunting trout
Ospreys have been known to hunt ground squirrels, but this is rare. Ospreys’ diets consist of 99% fish, but they have been known to hunt land mammals when their lake feeding grounds are frozen over.
Similarly to squirrels, Ospreys have been observed hunting land mammals. However, this is a rare occurrence.
There is no real evidence that Ospreys eat ducks, though they have been known to eat some small birds in isolated cases. But, by and large, it’s safe to say that Ospreys don’t eat ducks.
A successful hunt for a fish
Ospreys have been sighted eating lizards and snakes in Africa. However, this is rare and only happens when Ospreys are first arriving during migration and have not yet located a reliable fishing ground.
Ospreys have been observed eating iguanas after they migrate to Africa. Rock iguanas are often found near water, hence why Ospreys likely hunt them from time to time.
There’s no evidence that Ospreys eat otters.
There’s no evidence that Ospreys eat cats.
There’s no evidence that Ospreys eat dogs.
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