Interesanti... no LK:
Owlie
Re: Estonian Osprey Nests Ilmar & Irma ~ DISCUSSION~ 2014
September 7th, 2014, 9:40 pm
Urmas wrote:
--- Installing of artificial nest for our pair may be a disturbance of natural selection, though. Nature is very diverse and good things can turn bad in other background.
I will remember that Ilmar's previous nest fell down by a storm and this new one was installed by humans nearby the old one.
In what way artificial building of the nest can "disturb" the bird family development? I mean we have seen these two years that the osprey family in this nest works - fine (as we spectators can experience it)? With exception of Kaari's fate last year. And the middle egg's nonhatching this year. Can these exceptions have a connection to the artificiality of the nest? Rather than for example climate conditions?
andi7
September 7th, 2014, 9:52 pm
@Owlie: Evolution could not work, when humans interfere with nature. If an osprey has "bad" genes (e.g. too dumb to build an own strong nest) and humans help him building, his offspring and thereby his genes will survive. So mutation and selection won't work. Maybe his offspring is also not able to build good nests without human help. Even if his chicks have no own offspring, they will compete for resources with other ospreys, affecting the population of ospreys with "good" genes.
Kukelke
September 7th, 2014, 10:38 pm
andi7 already explained the mechanics, but to answer you specific question about these exceptions: No, I don't think that the death of Kaari last year and the non-hatching of the 2nd egg this year have something to do with an artificial nest.
Kaari could have been ill, or suffered from a genetic defect (also that is evolution at work), and it's fairly common that not always all eggs will hatch. Sometimes the egg is not fertile, or it never developed beyond the initial stage, sometimes the chick dies in the eggshell because the shell is too hard or the chick too weak to get out (again, evolution at work), a bit like spontaneous abortions and stillborns in the human species.
Kukelke
September 7th, 2014, 11:27 pm
andi7, I agree completely with the mechanics you describe, but perhaps the specific use of the example of nestbuilding is a bit unfortunate here. Things are a bit more complex than that:
Nests can be occupied for 50 years or more in a row, but by different ospreys. Ospreys do take over existing nests by just chasing off the resident birds (like what happened this year at the Alcoa nest where the resident pair, breeding there for years, was chased off by another pair of first time breeders), or a bird of an existing nest is replaced by an other when the resident bird fails to return. An example of this is the Manton Bay nest at Rutland Water where there was a pair originally, and first the resident female didn't return from migration and was replaced by current female Maya, and this year the original male failed to return and was first replaced by a male called 28, and a few weeks later this 28 was in turn chased off by another male called 33. So now there's a complete new pair on this particular nest, and none had to build it.
Having said that, I also want to point out that ospreys have some 30 million years of evolution in their genes, and that includes nestbuilding.
So, if an osprey would be too dumb to build a nest, there are other natural opportunities and possibilities to get a nest of his/her own, and successfully breed there and give the 'too dumb to build a nest'-genes further to next generation(s). It's rather the whole package of qualities which determines if a bird is successful or not, and, in an individual a less developed skill (nestbuilding for example) can be compensated for with a very high developed skill (like fishing).
Perkons is a good example of that: he has superb fishing skills; his chicks and female have never been without food for more than 6 hours, and he brought almost exclusively big fish, but his nestbuilding skills are rather lousy. He hardly ever brought a decent stick to the nest, almost only twigs and bundles of grass and moss. Perkons is also very eager to incubate the eggs and Lauma has a hard time to get him off the eggs after a break, and he's eager to feed the chicks (directly or via feeding Lauma feeding the chicks).
Ilmar on the other hand, is a keen nestbuilder and he comes dragging with one stick after the other. His fishing skills are good, but not exceptional compared to other osprey males, and although his chicks always get enough to eat, Irma and himself not always do. Ilmar hardly ever feeds his chicks directly, and he only incubates the eggs when he has to, when Irma makes very clear she wants a break (but then he performs his task well), but as soon as Irma returns, Ilmar flies off again.
Different individual behaviour and skills, and yet both Ilmar and Perkons are very successful ospreys in terms of breeding.
Kathy1229
September 8th, 2014, 6:07 am
Love learning from these discussions....if we could take all the strong points of Ilmar, Perkons, Madis , Stan, Steve and Monty we could have a nest- building, fish- catching, incubating, osprey-let feeding super Osprey....perhaps one of the osprey-lets from the nests of this year could be just that, the super Osprey that will do all of these things and do them better than their parents...but, if not, they will still be super birds....migrating, surviving and returning to pass on their genes is a super feat in itself...and they will do just fine not being a super bird...they will just be the best that they can be. Wasn't this the most spectacular season this year? I hope everyone enjoyed watching as much as I did.....
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