Ospreys have been around for a long, long time. They have hardly changed in at least 15 million years and the last time when the osprey had a common avian ancestor is a lot further back in time still. It is a remarkable testament to the success of this fish-eating raptor that the very features that give the osprey such an elegant advantage for their specialised way of hunting have changed little over evolutionary time.

So, what adaptations does the osprey possess that no other bird of prey has? Here are just a few:

Legs and Feet: Ospreys have disproportionally long legs to enable them to lunge for their prey and once a fish is caught, it is carried away torpedo style with the head facing the flight direction for maximum aerodynamic efficiency – no fancy wind tunnels required here. Massive sharp talons grip the fish, while backward-facing hard scales on the legs help prevent the live prey from slithering away. On the bottom of the feet themselves are specialised adaptations called ‘spicules’; the skin is formed into multiple barbs which further help the osprey catch, carry and eat its prey.

'Spicules' evolved milions of years ago and give ospreys an advantage when catching and carrying fish

Finally, and if that wasn’t enough for the hapless fish, the osprey can reverse one of its toes on both feet so that it has two digits facing forward and two facing back. The osprey is the only bird of prey out of 300 plus in the world that has this ‘zygodactyl’ toe arrangement – perfect for catching and eating fish.

Beak and Eyes: Like most birds of prey, the osprey has incredible eyesight, at least six times better than humans. It can spot camouflaged, bottom-feeding flat fish, for example, from 100 metres away, and once it starts its dive, the osprey calculates the diffraction angle compensation required because its target is submerged in up to a metre of water. Once an osprey hits the water, it has specialised valves inside the slit-like nostrils that close, preventing water from entering the nasal system.

Nora demonstrates some of her evolutionary adaptions that make ospreys so successful at catching and eating fish

The osprey has many other adaptations, too, that enable it to exclusively feed on fish. The intestine, for example, is longer than usual and it has special enzymes in the stomach and intestinal tract that aid fish digestion.

Isn’t it incredible to think that when our ancestors first thought about leaving behind an arboreal lifestyle in Africa and standing upright around five million years ago, the osprey at that time looked more or less exactly the same as today’s birds? Nature has a way of keeping and maintaining highly successful evolutionary designs – think of insects, the crocodile, the king crab and the Fender Stratocaster.

Monty closes his nasal valves shortly before hitting the water at 30mph

These birds have been part of our evolution. Almost everywhere homo sapiens have reached across the planet, almost everywhere where they came across water, the osprey was there already. How utterly brilliant they are now back breeding in Wales, England and Scotland and many other parts of the world where they had become extinct.

Strange Behaviour?
Yesterday we witnessed some astonishing behaviour. Firstly, it was curious to see Nora bringing a fish that Monty had given her a few minutes prior, back to the nest. Monty was taking his usual turn incubating the eggs when Nora returned with the mullet. She then started eating it. Ospreys rarely eat their prey actually on the nest unless they have chicks to feed.

Then, and most astonishing of all, it appears that Nora was trying to feed the mullet to Monty!! What’s going on?

Have a look at Monty’s face…Priceless

I, nor any of my colleagues, have seen this before. We saw last year that incredible ‘practise’ behaviour where Nora seemed to be feeding non-existent chicks at the edge of the nest as her first attempts had proven unsuccessful. Is this the same kind of displacement behaviour? Nora is around two weeks from seeing her eggs hatch, but clearly some of those innate maternal instincts have kicked in, spilled over and manifested themselves in the behaviour we saw yesterday. Remarkable.

I wonder what other facets of the osprey’s ecology we’ll witness this year through the camera’s lens.