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Osprey egg raid attempts by pine marten discovered

New footage has revealed this year’s osprey chicks survived two close shaves with a tenacious pine marten. The Loch Arkaig youngsters were named Mallie and Rannoch after a vote among nestcam viewers worldwide. But it could have been a different story. It seems the clutch of eggs were almost a late night snack for the hungry predator.

Repeat invaders

We launched our live internet camera stream supported by players of People’s Postcode Lottery in 2017. Despite a marten checking out the Loch Arkaig nest early on, novice parents Louis and Aila successfully raised their first chick, Lachlan.

But in 2018, the season came to an abrupt end when a pine marten managed to steal all three eggs from the nest.

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We have since discovered a marten attempted another egg raid this year. Fortunately this one was repelled by our first line of defence.

Marten-proofing measures

In a bid to protect the osprey nest, we have put several measures in place:

  • a slippery sleeve around the base of the trunk, covered in grease so martens can't grip to climb
  • a band of electrified wire further up the trunk to gently jolt any raiders
  • removal of all low hanging branches so martens have no jump-on points
  • a layer of chicken wire running through the nest platform. Martens have been known to tunnel through the bottom of nests to remove eggs from under a sitting osprey!

All these measures except the electrified wire were in place in 2018. The marten’s entry route appears to have been a large branch, blown down from a neighbouring tree, which ended up leaning against the ospreys’ tree.

Caught on camera

To monitor how the marten-proofing was performing this year, our osprey adviser Lewis Pate left a trail camera at the foot of the tree. This motion-triggered camera captured shots of every visitor who came to call.

When Lewis ringed the osprey chicks on 4 July, he retrieved the memory card, revealing shots of the would-be egg thief! The marten had tried and failed to scramble up the slippery covering at the base of the tree.

The pine marten's attempts were foiled by the protection measures (Image: Lewis Pate)
The pine marten's attempts were foiled by the protection measures (Image: Lewis Pate)

Less of a threat to the nest, a young badger was also snapped having a look around.

Our osprey audience around the world has been fearful of another marten raid, so it’s good to see that the defences have been effective.

However, we don’t think the species need to be protected from each other in a wider sense. We have intervened because we want people to be able to follow this osprey family raising chicks. A lot of time and effort has been put in to offer the livestream so we feel it is reasonable to fit some marten-proofing.  

An inquisitive badger investigates the osprey tree (Image: Lewis Pate)
An inquisitive badger investigates the osprey tree (Image: Lewis Pate)

It is entirely natural for pine martens to take osprey eggs and the mammal is not a threat to the ongoing survival of the bird.

Their biggest problem has been people.

A shared history of human persecution

Ospreys and pine martens were both wiped out from vast areas of the country by the actions of people.

Ospreys were shot for taxidermy, or because they were seen as a threat to game. Collectors also took their eggs. Appallingly, they became extinct in the UK in 1916. The last pair nested on an island in Loch Arkaig.

The comeback began in 1954 when a pair settled to breed at Loch Garten in the Cairngorms. Now thanks to decades of work to reintroduce this magnificent bird and protect its habitat, we have more than 300 breeding pairs in Britain. 

Although the pine marten was one of the most common carnivores in Britain, it is now one of the rarest. Their dramatic decline was caused by loss of habitat, the fur industry and predator control associated with game shooting. By the early 20th century, the species was close to extinction, surviving in just a few scattered pockets.

We're working hard to protect pine martens as well as ospreys (Photo: David Sewell/Alamy Stock Photo)
We're working hard to protect pine martens as well as ospreys (Photo: David Sewell/Alamy Stock Photo)

Fortunately, pine martens are now protected and numbers are growing as conservationists work to save the species. We have joined the Pine Marten Recovery Project with the Vincent Wildlife Trust and others to help boost pine marten populations. In fact, 51 pine martens from healthy populations in Scotland have been carefully moved to Wales. After a good deal of research and survey work, they are now well established in the Welsh forests.

At Loch Arkaig we have taken our marten-proofing precautions at our nest as far as we think it is reasonable to go. Both now back from the brink of extinction, these two species are likely to remain at the heart of the drama for years to come.

Don’t miss the ospreys’ summer in Scotland

Oblivious to all this activity from the heights of their nest, Louis and Aila have successfully raised Mallie and Rannoch.

Rannoch (left) and Mallie (Photo: Lewis Pate)
Rannoch (left) and Mallie (Photo: Lewis Pate)

There are a few more weeks to enjoy the family yet before the youngsters fledge and all migrate south. Follow all the action on our live streaming nest camera supported by players of People’s Postcode Lottery.

Tune in to the action live from Loch Arkaig

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