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Bonelli's Eagles losing nests to Griffon Vultures and Golden Eagles

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Offline Steve West

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« on: January 26, 2008, 11:50 AM »
I went to els Ports (Beseit/Tortosa) yesterday to do a common bird census which I have been doing for the last 5 years or so for the Institut Català d'Ornitologia. It's a wonderfully scenic 3 km transect following the course of a river gorge. Birds are not that abundant in the gorge itself although the surrounding olive groves and pine woods make up for that. Usual species include Firecrest (also Goldcrest in the winter), COal Tit, Bonelli's Warbler (summer), Sardinian Warbler, Blue Rock Thrush and more. FOr the last two transects I've seen a Peregrine sitting in exactly the same place (no not stuffed because it was preening), the ever-radiant Kingfisher and a dozen or so Griffon Vultures.

What I haven't seen for the last couple of years is the Bonelli's Eagle. Now that's a surprise and a shame because a territorial pair has one of its known nests in view of my transect, and 2 years ago they used to offer wonderful views of synchronised flying in the breeding season. Last year I searched around their nest but only saw two Griffon Vultures. The same happened yesterday.

It's a known fact that the recent recovery of Griffon Vultures has been to the detriment of Bonelli's Eagles in some places where the two species coincide. The Griffon Vultures oust the Bonelli's Eagles and take over their nests. Apparently the same has happened, for example in Extremadura, with Golden Eagles ousting the Bonelli's Eagles too.

This is not meant as a harangue against Griffon Vultures. Bonelli's Eagles (less than 750 pairs in Spain of 1,000 in all of Europe) are under threat from other sources which have a greater impact on their populations than competition from other birds of prey: electrocution, habitat fragmentation and loss, shooting and disturbance.

But it does annoy me that I can no longer enjoy the double treat of the scenery of els Ports and the spectacle of Bonelli's Eagles. 
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Offline Clive

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« Reply #1 on: January 26, 2008, 12:28 PM »
Interesting Steve,

Down here in Grazalema the Bonellis that reside in the garganta verde area moved sites from one side of the cliffs to another more wooded area (or so we think). We saw them in the new area a few times. They are around a corner from the viewing area...

The garganta verde holds over 400 pairs of griffons and just one pair of bonnelis. I was under the impression that the single pair would be Ok in the defence of their nest as we often saw them dive bombing and removing feathers from the griffons...
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Offline tonyninfas

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« Reply #2 on: January 26, 2008, 18:01 PM »
Hi Steve
What a pity you did not let us know that you were in the Els Ports.  Would have loved to have met up.
Which gorge were you in ?
Tony

Offline Steve West

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« Reply #3 on: January 26, 2008, 18:51 PM »
Hi Steve
What a pity you did not let us know that you were in the Els Ports.  Would have loved to have met up.
Which gorge were you in ?
Tony

Hi Tony

I shouldn't really reveal that information over the internet. Although it's fairly common knowledge in the local area revealing the location of rare birds of prey's nests on the internet is not recommendable. I was on the northern side of Els Ports. I will be down there again sometime between mid April and Mid May at least, so maybe that would be a good time to meet up.

Regards
Steve 
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Offline nick

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« Reply #4 on: January 26, 2008, 23:11 PM »
Didn't we have a post last year about griffons taking the nesting spaces of peregrine falcons?

I heard their rise has also affected Egyptian vultures negatively as these migrate and by the time they're back in Spain, many of the nesting sites are taken up.
Nick
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Offline tonyninfas

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« Reply #5 on: January 26, 2008, 23:17 PM »
Hi Steve
Yes, wasn't thinking and fully understand.
Hope to meet up when you're next this way.
Tony

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Offline ebromarg

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« Reply #6 on: February 05, 2008, 19:08 PM »
Hi Steve and Tony
We were regularly sighting a pair of bonelli's and then later their offspring on the southern side of Els Ports in a couple of our local valleys last spring/summer.  If you wanted to email me I could give you the location. Not sure exactly the position of the nest but  they were definitely doing their best on occasions to chase off any griffons coming near. 
Margaret
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