Golden Eagle Pellets

(Originally published in Scottish Bird News 78 12/2005 p18)

After watching the young Golden Eagle practising its hunting technique on a lamb, featured in S.B.N No 77, I decided to try and locate some pellets, the regurgitated indigestible remains of a raptors meal, in an effort to determine exactly what the golden eagles in this area were eating.

To achieve this, I first of all studied Ordnance Survey maps covering a habitat of hill and moorland where I had regularly observed these birds and measuring approximately 12 square miles.

Routes were planned to cover prominent hills but after a number of weeks in the field, it soon became apparent that the eagles I had been observing preferred to perch and dine either on top or on the ledge of a rocky cliff face. Some of these were as little as 12 foot high and many faced onto a loch.

At one elevated site overlooking a deep dark loch, I discovered the remains of various birds and mammals including heron, raven, greylag, rabbit and the skull of a hedgehog.

The pellets collected were split almost equally, half comprising of fur and feather while the remainder were formed entirely of sheep’s wool.

The large size of these castings coupled with the fact that I had watched golden eagles perched there in the past left me in little doubt what had produced them although for a moment I did consider the possibility that a white tailed sea eagle could have been the culprit.

The pellets of golden eagles and white tailed eagles are indistinguishable but as I had never spotted any of these larger birds in that particular area, I felt confident it was golden eagle pellets I had discovered, although I must confess I could not be absolutely certain.

Remnants of two lamb’s legs did confirm what I already knew but proved to be a small part of what had been eaten.

However, it wasn’t just the golden eagles diet that interested me but how they went about catching their prey.

The remaining primary feathers of the heron and raven I mentioned earlier had intrigued me. They were short and the shaft ends were still showing signs of growth, an indication that they were most likely youngsters probably not long out of the nest.

My theory, and I stress the word theory for I have not witnessed what I am about to suggest, is that the eagle, particularly during the summer months, would sit on a lofty perch above the loch, beneath the skyline, camouflaged by a backdrop of rocks and heather.

Families of birds and mammals attracted to the water to drink or bathe would then become easy targets, especially the naive youngsters, and the eagle, with the advantage of surprise and height would swoop down at the precise moment, crushing its unsuspecting prey in its powerful talons.

At home I teased and prodded at the pellets thinking that, with many years of roving the countryside under my belt, I would surely be able to identify some of the bits and pieces that emerged.

After all, it is well documented what golden eagles eat, it was just a matter of finding these things or to be more precise, the fractured remains of these things that were now part of the tightly compressed balls of fur and wool I had in my possession.

Strange and weird items started to appear and it soon became clear that I needed the assistance of a specialist to analyse the golden eagle pellets properly.

Fortunately, Dr Mick Marquiss at the centre of Ecology and Hydrology in Banchory has agreed to do this and I will submit his findings once he has reached his conclusions.

(a follow up article is available online)