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Thursday, 26 February 2009 22:29

GE Update 2008

Eagle chick in flight Eagle chick in flight (c) Laurie Campbell

Breeding Season 2008

Site: D01 breeding pair
1 egg laid in 2008. Two eggs laid in 2007 but did not hatch.
Male Yellow 2 Spots from: Glen Affric, Invernesshire 2001
Female Blue O from: Lude Estate, Tayside 2002
This pair bred again in 2008, but again for the fourth year in a row this territory failed to produce a chick or even hatch an egg. The birds were on site throughout the late winter and early spring. They laid an egg and their incubation seemed consistent. But yet again the egg failed to hatch. Unfortunately, after the due hatch date had passed and we went in to retrieve the egg for analysis, it had gone, probably taken by a nearby pair of Ravens. So we cannot say if the egg was fertile or failed during incubation. Only one egg was laid, which would suggest some constraint on the condition of the female. Some experts say that the egg volume to adult female body mass ratio is so small in this species, that the condition of the female prior to egg-laying is not as important as it is in other species. However, falconers often talk of the importance of calcium in egg production. We are aware that this territory has an apparently low level of live prey and the availability of local carrion, especially sheep, may limit the amount of small bones and calcium consumed.

Site: D02 single male
Male roosting on site in 2008. Single Male on site in 2007.
Male Yellow 3 Spots from: Glenfinnan, Lochaber 2001
Single male seen on site throughout the 2008 season. The male was seen occasionally in the company of other eagles, in late December and early February 2007/2008, but failed to form a pair. In its seventh year, this bird still retained some white on its under tail and under wing.

Site: D03 unoccupied
Unoccupied in 2008. Last used in 2006, vacant in 2007.

Site: D04 single male
Male roosting on site in 2008. Male on site in 2007.
Male Green O from: Skye 2004
Noted on site repeatedly from early spring ? always seen on its own, throughout the season.

Site: D05 pair
Pair present added some material to 2007 nest. Fledged 1 Chick in 2007.
Male Blue 3 from: Skye 2002
Female Yellow Diagonal Bar from: Assyant, Sutherland 2001
The pair was again on site during the pre breeding season but failed to breed this year. The early part of the 2008 spring contained very good weather and it is disappointing that this pair did not breed at all in 2008. The pair had been roosting a short distant from the 2007 nest, throughout the autumn and winter of 2007. The male was seen in the vicinity of the 2007 nest a few times in 2008, but only a few bits of heather and a few clumps of Molinia (grass) were added to the old nest.

It was difficult trying to locate the female during February and March 2008. It began to dawn on us over the Easter weekend (22-24 Mar 2008) that this pair was not going to breed. They were seen flying together, just prior to dusk, on two separate evenings at a time when one of the adults should have been incubating. A lot of effort was invested trying to follow these birds thereafter to ensure they did not nest later in the season or elsewhere. So it was disappointing, but we hope to see more chicks in future years. The late Dr Jeff Watson, put it very neatly, ?Spring in Scotland?s eagle country is a season full of extravagant expectation and unreasonable optimism?

Site: D06 pair
Pair on site, new nest fully built (lined but not cupped) in 2008. Pair on site in 2007.
Male Orange 1 from: Uists 2005
Female White 7 from: Near the Great Glen, Loch Ness 2006
This pair had been on site the previous season wandering over a wide home range, even though the female only reached her second birthday and became a three year old bird in May 2008. In early February, this pair (2nd yr female and 3rd year male) was seen soaring together, over a wide area, with the female repeatedly dropping and snatching the same sprig of heather.

By early April they had built a big eyrie, of sticks and heather ? one of the bigger nests in Donegal. Nearby there were plenty of moulted feathers and splashes and prey remains from Fulmars and rabbits. They have been seen hunting rabbits near the coast during the last two years. The nearest farmer, who had expressed concerns regarding the arrival of the eagles in spring 2007, said his 2008 lambing season has been excellent. He normally expected to lose or put down 6-8 lambs due to damage from Hooded Crows, but in 2008 the Crows caused no damage and the farmer put their almost complete absence from his lambing fields down to the nearby eagles.

Site: D07 pair
Pair on site during the 2008 season. This male was often seen in this area in 2007.
Male Orange 2 from: Badenoch 2005
Female Unknown from: Unknown
This pair was seen together on 5-6 occasions wandering over some very suitable upland habitat in Donegal. Hopefully this young male (3 year old) will stay on site and attempt to breed in the coming years.


To date, including 2008, 53 Golden Eagles have been released in Glenveagh National Park. Overall we have not been able to release as many birds as we initially planned. Due to the widespread dispersal of the released birds in recent years, we are unable to estimate how many birds are still alive. We recognise that the lack of detailed data regarding the survival and movements of the immature and sub adult eagles is one of the primary problems facing this release programme. In Scotland, with their much greater level of eagle monitoring, both professional and voluntary, a similar paucity of sub adult data is a problem and monitoring is largely based on the monitoring of breeding pair at fixed locations.

There has been a considerable increase in the amount of Golden Eagle dispersal in recent years, due to the presence of up to 6 occupied home ranges now in formerly available habitat in Donegal. For example, in the spring and summer of 2008 confirmed Golden Eagle sightings with varying degrees of wing tag details, showed that 1`st year birds from 2007, had visited Counties Down, Antrim, Derry, Fermanagh, Tyrone (5 of the 6 Counties in Northern Ireland) and Monaghan, Leitrim, Sligo, Mayo, Galway and Clare. So these young birds are now wandering around the majority of the North and West Coastal Counties in Ireland.

For example, Blue Yellow 5 was last seen in Glenveagh National Park on 24 January 2008 and was next seen in the Slieve Aughtie Mountains, County Clare on the 2 May. The Wild bred Chick from 2007 was last identified in Glenveagh on 26 December 2007 and appeared to have dispersed shortly afterward.

There were also records of White tagged (5 birds released in 2006) Golden Eagles from Lough Swilley, Donegal, Glenveagh National Park and Achill Island Mayo during the spring also. In addition to these white tagged sightings there was the territorial White 1 in Territory D06.

Release Programme

In 2008, 5 chicks were imported from Scotland. Unfortunately it was a difficult year and a chick from the Uists died shortly after arriving in Scotland, though it was noticed to be unsteady even whilst in Scotland. The post mortem, showed it had a number of underlying ailments in several organs suggesting some form of coli septicaemia, which appeared to have developed shortly after hatching. Similar mortality during the late chick stage has been noted in recent years in several broods in the Uists and may warrant some detailed analysis.

In addition, another bird from the Western Isles was collected from Skye and despite our best efforts was not released as it never developed any flying ability. Though the bird was considerably smaller that it male sibling it the nest, I decided to collect this female as the 3 other birds collected prior to this were male and we needed females. Unfortunately, in hindsight this was the wrong decision. Veterinary analysis identified a low level of calcium in this chick, which may have been one of the causes for its inability to fly. Previous blood sampling from other released birds showed that calcium levels were normal and chopped up rabbits, including bones, are routinely provided for the chicks during the captive phase. But again the levels of calcium and general physiological status of this top level predator may be an under recorded constraint factor and reflect a paucity of small prey species in some locations.

Period Minimum known 1st Year Survival No Released
2001-2003 72% 25
2004-2006 57% 21
Total 65% 46

The minimum known 1st year survival rates for females (61%) and males (68%) are quite similar.

Last modified on Friday, 09 March 2012 10:38