The Isle of Wight's White-tailed eagles love to go a-wandering - but not (for some reason) to Wales or Ireland

                                               

Tim Mackrill - expert on fish-eating raptors 

WHEN White-tailed Eagles returned to England almost five years ago, no one expected Lapwings to be a beneficiary species.

But early evidence is indicating that their presence can displace Buzzards which prey on Lapwing chicks.

By contrast, though White-tailed Eagles do feed on birds, their targets tend not to be Lapwings but Coot or unfit specimens of larger species such as Grey Lage and Canada Geese.

This information and much more featured in  a fascinating weekend talk by Dr Tim Mackrill. It was entitled The Return of The White-tailed Eagle to England.

In his illustrated presentation on Saturday to the annual meeting of the Lincolnshire  Bird Club, he noted that this majestic raptor, the fourth largest eagle in the world, used to be widespread in England until it was persecuted to extinction.

Why the persecution? Tim did not go into detail but noted  a religious link. Fish-eating is associated with Good Friday which is why, through centuries, substantial bounties were placed on the killing of both this fish-eating species and another, the Osprey.

What initiated the return to England? It dates back to June 2019 when the  highly-respected Roy Dennis Foundation introduced birds from  Scottish nests to the Isle of Wight where the bird had been extinct since 1780.

As Tim described it, this was born of the Foundation's conviction that the time had come to start "undoing a past wrong". 

The initiative has not been without controversy, especially among a minority of farmers.  

                                             

High in the sky! Such a magnificent raptor!

The species, especially young birds, feed extensively on carrion but, contrary to scare stories, there is no reliable evidence that they attack lambs or any other livestock.

Those animal carcasses on which they are seen feeding have invariably already died beforehand of other causes.

In his talk, attended by an audience of about 40, at the education centre at Whisby Nature Park, near Lincoln, Tim described how, in order to forestall any risk of imprinting, young birds were gradually introduced to their new Isle of Wight environment in such a way that the human involvement was imperceptible to the birds.

Although some of the 29 releasees since 2019 have died - for instance from avian influenza, ingesting poisoned rats, pylon cable collision or even, in one instance,  impact from a train while feeding on a dead deer on a  railway line.

Early indications are that survival rates seem to be greater among females, The reasons for this are not clear, and, according to Tim, it may just be happenstance.

One remarkable bird has managed to thrive despite somehow losing its right foot - thought to be the result of electrocution, entanglement with a fishing line or having been caught in a spring-trap.

Thanks to the attachment to the released birds of satellite tags (costing about £1,000 apiece). a huge amount is known about the nomadic behaviour of the species.

Tim and his raptor-studying colleagues are now able not just to track tagged birds but also to predict their movements up down the whole length of Britain, thence sometimes across the English Channel though western Europe to Scandinavia and back to the Isle of Wight.

It seems that the birds have favourite perching sites trees - such as willow, Scots pine and birch -  where, almost hidden from human view, they may spend as much of 90 per cent of their time doing absolutely nothing.

"They seem to favour the sit-and-wait method of foraging," said Tim who noted that, as birds grow older, they became increasingly adept at stealing food from other birds, even snatching prey from Herons, Peregrines, Buzzards and Marsh Harriers.

Basing his talk mostly on scientific data, peppered with the occasional anecdote, Tim also touched on  plumage moult, breeding behaviour, historical context, Scottish introductions and how the diets (including cuttlefish and grey mullet) of individual birds change during the four or five ears or so while they grow from juveniles to adults. 

He also noted the significance of White-tailed eagles in generating tourism - thought conservatively to  be in excess of £5-millon per annum on Mull and more than £2.4-million the Isle of Skye. 

Contrary to widespread belief that White-tailed Eagles are solely birds of wild coasts, they breed extensively at inland sites in Germany and Poland, and they regularly nests on the outskirts of cities as large as Rotterdam, Helsinki and Hamburg.

Yet, despite the accumulation of knowledge about the species, it still  retains sufficient secrets to be classified as a bird of mystery.

Why, for instance, given the abundance of estuary and other suitable feeding habitat, do the nomadic flights of released birds exclude almost the whole of Wales and Northern Ireland? 

"Maybe it has something to do with prevailing winds, but we don't really know," said Tim.

Also unknown is the extent of its eyesight, though, according to the speaker, its detection ability could, incredibly, be as far as 10 miles! 

Tim has recently published a highly acclaimed book, The Osprey. He is pictured below with  some of those who attended his talk near Lincoln - from left, Mike Harrison, Chris Grimshaw, John Watt, Jon Cooper, Phil Espin and David Cohen.