Soaring across the sky with a wingspan of 2.5 metres, white-tailed eagles are Britain’s largest birds of prey. Once widespread across England, persecution caused their extinction with the last known pair breeding in 1780.
In 2019, Forestry England and the Roy Dennis Wildlife Foundation began a reintroduction programme based on the Isle of Wight to restore these iconic birds to the English landscape.
We caught up with project officer Steve Egerton-Read to share the progress of the birds and his reflections on some of this year’s stand out moments.
A big surprise
From the outset our goal has been to create a sustainable population of white-tailed eagles, establishing 6 to 8 breeding pairs. When we began five years ago, with knowledge of past projects and the biology of white-tailed eagles, the earliest we expected breeding to begin was 2024. So it was a great surprise that it actually happened this summer.
This was a huge moment for the project, and the first-time eagles have bred in England for over 240 years. It was also somewhat unexpected in terms of which birds were the first to breed.
We closely monitor all the released eagles, with a particular focus on looking for signs of breeding behaviours. We have watched as three pairs became established on the south coast, displaying behaviours including aggression towards other eagles to defend territory, courtship behaviours and nest building.
One pair took these behaviours a lot further by attempting to breed. Given that these birds were only three years old, and white-tailed eagles tend to start breeding at four or five years old, they weren’t the pair we expected to be first!
First time parents
The pair built their huge nest, laid and incubated an egg, and shared the roles of feeding and caring for their chick up to fledging. Truthfully, we would have been happy had they reached any of these stages at this age, but we are absolutely thrilled that they have successfully gone through the lot.
Now, several months on from leaving the nest, the ‘chick’ is still hanging around his parents. Despite the fact that he is fully grown, they will continue to feed him and until they start to prepare for the next breeding season. At that point if he hasn’t left by his own accord, his parents will force him out.
Once he becomes fully independent, he will need to find his own food. In the spring he is likely to start a period of exploring more widely across the country, just like his parents did following their release as young birds in 2020. He is fitted with a satellite tag so that we will be able to follow his progress closely.
There is of course no guarantee that this pair will succeed again next year, but with this early success and other pairs establishing in southern England, we will be closely following all developments as we approach the next breeding season.
What’s on the menu?
Diet is one the key areas we study. We’ve been spending a lot of time closely watching the eagles hunting and feeding, with the help of a team of dedicated volunteers. Over 5,000 hours so far! Where other studies focus solely on collecting prey remains from nests or analysing pellets, our study is somewhat unique by also observing the eagles. This not only helps us understand what the eagles are eating but also how they are acquiring these meals. As all of the birds are fitted with satellite tags, we can also identify the individual eagle observed.
We have discovered that just as their diet changes with age, so do their feeding strategies. For young birds, carrion (scavenging dead animals) is vital and makes up more than 50% of all their food. However, as eagles approach breeding age, they become proficient hunters, but also become adept at stealing food from other predatory birds, such as buzzards, kites, harriers, peregrines, ravens and herons! They exhibit a preference for this fresh source of food and carrion features as only 10% of their diet.
Our study revealed one food item that sets the eagles on the south coast apart: cuttlefish. The resident pair on the Isle of Wight have been regularly seen catching these molluscs during spring and summer. We don’t believe this has been reported in other white-tailed eagle studies.
A key reason for choosing the south coast of England to reintroduce white-tailed eagles was an abundance of suitable prey. Our study makes it clear there is certainly a wide variety of food available for these birds all year round.
New birds released
Each year we release young white-tailed eagles from our base on the Isle of Wight. Chicks are collected from nests in Scotland (under licence from NatureScot), transported south and then looked after in special aviaries that recreate the experience the birds would have in the wild. When the young birds are ready to fledge they are released under licence from Natural England and begin to explore the landscape.
This year we released another cohort of young birds. As we have seen with the eagle born in the wild this year, young birds usually rely on parents for food after fledging. We replicate that process by supplying fresh fish on large platforms close to the release area and continue throughout the winter to give the birds the best chance of survival.
Come spring the released juveniles tend to explore far and wide, learning about the landscape, before returning to the south coast of England. Previously one of the released birds, known as G463, travelled as far as the Netherlands, Germany, Denmark and Sweden before returning south to set up a breeding territory in Poole Harbour. It will be fascinating to see where this year’s cohort travel to, and we will be closely monitoring them. We can't wait to share the next chapter in the story of England's white-tailed eagles.
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