I always thought there were a slew of different osprey species, just like there are many different types of eagles or hawks. It turns out this is very wrong — in fact there is only one species of osprey, and it is just so adaptable that it lives all over the place.
In fact, ospreys can be found on every continent except Antarctica. They are only seasonal visitors to South America and Indo-Malaysia, and are especially abundant in Scandinavia and Chesapeake Bay in the United States. Habitat requirements for ospreys are fairly simple: they need safe nesting sites and fish-rich water. They can use almost any source of water, including salt marshes, mangrove swamps, lakes, rivers, and reservoirs.
Ospreys reach lengths of 55-58 cm, and have a wingspan of up to 170 cm. They have dark brown feathers covering their backs, with white underbellies. Ospreys have light grey feet, and black beaks. They are notable for the black stripes that go through both eyes, giving them the appearance of wearing a mask.
As I said earlier, ospreys need to be near some kind of fish-infested water to survive. This is because, unusually for a bird of prey, ospreys are almost exclusively piscivores (fish eaters). They aren’t picky about what type of fish they eat, with North American birds eating more that 80 different species of fish.
Ospreys have a number of helpful tools to aid them in catching slippery, slimy fish. They have long legs, each with curved claws and a reversible toe that makes gripping fish much easier. Their feet are also equipped with spicules, which are roughened footpads that also improve ospreys’ grips. Since catching their prey means ospreys will inevitably get wet, these birds have thick oily feathers, and nostrils that can close to prevent water form entering their noses.
Ospreys mate for life, with both males and females working to build the nest. Nest sites are used year after year, with the birds spending some time repairing and maintaining the nest before eggs are laid. Females lay between two and four eggs, which hatch after 40 days. The eggs are laid one to two days apart, which means the first laid egg hatches earlier than the last. This results in chicks of various sizes, and often smaller chicks are outcompeted by their older siblings. During incubation and after the chicks are born, male ospreys are kind enough to bring the females and chicks fish. The chicks fledge between 48 and 76 days of age, and become sexually mature at three years.
The nearly exclusive fish-eating habits of ospreys have made it a very unique bird of prey. So unique, in fact, that these birds have been placed in their own family, Pandionidae. And thanks to their ability to eat a plethora of different fish species, these guys have been able to flourish all over the world.