Golden eagle diet on the Isle of Lewis

(Originally published in SBN 80 06/2006 p18)

The results of the analysis carried out by Dr Mick Marquiss on the Golden Eagle pellets I collected from my designated 12 mile square plot (see SBN 78, December 2005) have shown just how diverse the diet of these raptors is on the Isle of Lewis.

The 27 pellets that were tested were gathered between August and November 2005, but it is worth mentioning that a number of these could have lain for a considerable time before I found them, so some of the items discovered in the pellets could have been consumed earlier than this period. With this in mind it would be wrong to assume that the following list of prey or carrion is eaten only during this time of the year.

The results below are also preliminary, and I offer some thoughts on a few of the species found.

Golden Eagle Pellet Analysis, Isle of Lewis, 2005

Pellet contents	No of pellets
Sheeps Wool (evident in)	16
Vegetation debris	11
Waders(1 Snipe, 1 Snipe/Dunlin, 1 Juvenile, 3 others)	6
Greylag Goose	5
Rabbit	4
Red Grouse	2
Redwing	2
Hare	1
Hedgehog	1
Mink	1
Gull	1
Shag or Cormorant	1

Dr Marquis has pointed out,

Pellets reflect diet but there is a strong bias towards hair, and towards large animals. Thus the high proportion of pellets with wool does not mean that a similar percentage of the diet was sheep or lamb. Eating carrion sheep would leave eagles with a lot of wool in their crop

Greylag geese and Rabbits, both consummate grazers, are high on the list of the Golden Eagle’s preferred prey and are regarded by most crofters as unwanted pests. They devour the grass at an alarming rate that would other wise be eaten by livestock, and multiply just as quickly. Because of their rapidly increasing numbers, geese in particular have been identified as a major threat to sheep and cattle owners. One farmer I spoke to shoots geese on a regular basis in an effort to control their numbers but even he has admitted that he is fighting a losing battle. The news that Canada geese may be breeding here now as well and could possibly join the swelling population of Greylags will be of little comfort.

There are still some crofters, who ritually and traditionally persecute Golden Eagles either directly or indirectly, but by destroying what they perceive as their nemesis, perhaps they are instead getting rid of an important and natural ally. Yes, some Golden Eagles will kill the odd lamb; there is no point in continually denying this fact. However, there is evidence to suggest that when this does happen, the lambs that are taken are weaklings from poorly managed stock. I happened to meet a crofter in the neighbouring village gathering his stock at lambing time and asked him if he had spotted any eagles in the area recently. He quite bluntly replied that if he had, he would not tell me, or anyone else for that matter. When I asked why not, he went on to explain, "There are certain people who interfere with these birds if they find them and it is not the sort of action I approve of". After I assured him I had no such intentions he continued, "Eagles generally tend to avoid people and although I have watched them out on the moor, I have seldom found them hunting close to the village where my lambs were born. When the lambs are eventually allowed onto the moor, they are usually too large and healthy for Golden Eagles to Kill".

Crows and Black-Backed Gulls were I discovered his main foes- two birds that are killed regularly by eagles and it was encouraging to note that this particular crofter was well aware of this fact. Mink and Hedgehog, two alien species that are costing millions of pounds to eradicate, are also eaten, and so in conclusion, it seems that the Golden Eagles on Lewis are more beneficial than some may think.

I have now cleared all the pellets from the Golden Eagle roosts, perches and dumps that I know of in this area. By visiting these places regularly and dating the pellets as they are found, a pattern should gradually emerge, showing not only the diet of these magnificent raptors but just as importantly, the specific diet at any given time of the year.