White-tailed Eagle killed in fight over mate
A rare instance of a White-tailed Eagle being being killed another has been documented in Kerry in southwest Ireland.
The Golden Eagle Trust, a charity based in Ireland dedicated to the conservation and restoration of Ireland’s native birds, detailed the findings on the Facebook page, here is their update and the story of Red Dot.
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It’s been another good but mixed year overall for our breeding pairs of White-tailed Sea Eagles…but more of that shortly.
The last recorded loss of an adult WTSE was back in June 2015. So, it was a real blow to receive news on 21 April this year that a WTSE had been found dead in west Kerry the day before. Photos of the bird revealed it to be a breeding female, 2008 red dot, now in the second year of nesting with her mate, 2010 blue 15. Later that day, with help from local boatman Mike O’Shea, we were able to find her carcass on the lake shore. She was in great condition and weighted a whopping 6.4kg. While poisoning was uppermost in my mind at this time of year, toxicological analyses were negative for all the usual suspects. So, what could have killed such an apparently healthy big female right in the middle of nesting?
Apart from recovering the dead female the priority was to monitor the breeding effort at the nest. Would the nest be empty when checked? Estimates of when the pair laid suggested that they had about a week to go to hatching. Surely without the female to take over nest duties, even if the male was still there, there was little or no chance of success? The hike up to the nest observation spot couldn’t go fast enough. But there was the male sitting tight! The initial high of finding him still sitting was tempered pretty quickly by the realisation that he would have to get off to feed at some stage and the eggs would be at risk from chilling or nest predators.
While we don’t usually intervene in nesting efforts, it was felt there was nothing to lose by attempting to give the sitting male a helping hand by providing food within sight of the nest. Maybe he would sit and hatch the eggs if he had a food source nearby and only needed to leave the nest for a few minutes? Thanks to a local farmer we were able to get some food out quickly. Days passed and the male kept sitting. Then on 25 April blue 15 pulled it off, he hatched a chick solo! Likely the chick had hatched late the previous day, but a check revealed that he had not taken any of the food put out for him. Unfortunately that day was a typical ‘spring’ day, sunshine mixed with icy winds and hail showers. By the next day the nest was empty and blue 15 was gone, his valiant effort had come to nothing.
Results of the dead female’s post mortem were even more startling. She was in superb condition but it was clear that she been in a fight. Puncture wounds could be seen in her pectoral muscles that penetrated a few centimetres. The wounds were curved and could only have been made by another eagle’s talons! There was also a wound on the head. Tests for poisons or other potential causes of death were also all negative. So, our breeding female had been taken out by another eagle. Eagles can and do kill other eagles but this is usually the case in populations where most or all the available territories and mates are already taken by other established pairs. In these cases, non-breeders may have to wait many years for a vacancy to arise. Or they can risk a potential fight to the death to oust or kill one of the established pair.
This case led us to enquire whether this intra-specific conflict is seen much in other countries with larger Sea Eagle populations. Dave Sexton, RSPB Officer on the Isle of Mull, confirmed two cases this year, one in which a fight resulted in the death of a breeding male and his replacement by the new male, and another fight where one of the adults was later found washed up on the Scottish mainland.
Norwegian Sea Eagle expert Dr. Torgeir Nygård commented as follows:
“Territorial fights between adult WTEs with fatal outcome is not unusual here in Norway. I have experienced a few, in two a female was found killed, with the upper part of the bill removed. In one case, two females were found entangled In each other, not able to come loose, and both were found dead. Alv Ottar Folkestad has seen numerous examples of the same, and the impression I get from him is that females are more often involved than males. I suppose this happens when the population is becoming saturated, and when adult floaters are trying to acquire a mate and a territory for themselves.”
So, who could the usurper be? Days after the death of Red Dot another eagle was seen circling above the nest tree and even landed nearby. Thanks to the dedication (and no little skill!) of one of our nest volunteers Patrick McDaid, who had his camera at the ready, we were able to identify the intruder….2011 female black Dot 1!! Could she have been killed the resident female in a fight to gain a mate and his breeding territory? Would we ever know for sure?
Then on 7 August last came the news that male Blue 15 was back at one of his favourite fishing haunts some 10km from the best with a new female, black dot 1! Since then the ‘pair’ have been seen together a number of times. So, it seems like she got her man. Sad that it took the death of Red Dot but it looks like male Blue 15 will have a new breeding partner in 2018!
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19 September 2017
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