occasional
Well-known member
Your hypothesis seems to be that sparrows respond with such alacrity to the appearance of sparrowhawks that negligible mortality occurs, but their local ranges are then restricted, resulting in density dependent reduction in breeding success, which then causes a population decline which relieves the density dependent breeding depression. This is not impossible, but then you would have to explain why there has been a decline in adult and first year survival over the period of the decline (also in the withdrawn BTO report). In short we have a sparrowhawk-related population decline in tandem with a decline in adult/first year survival, and no evidence of decline in breeding success temporary or otherwise.
As far as I am concerned it is not my hypothesis, but rather your hypothesis, modified to take into account information which can be gleaned from contributions to this board.
You have then exagerrated the hypothesis by adding such expressions as "negligible mortality". If adult survival has declined, I, at least, am quite happy with that being part of "the sparrowhawk effect" and indeed it is what I would expect to find.
To put it simply, if one can find a hypothesis which appears to be consistent with all the evidence, both scientific and anecdotal, then that is the hypothesis which I would prefer to defend.
As far as I am concerned it is not my hypothesis, but rather your hypothesis, modified to take into account information which can be gleaned from contributions to this board.
You have then exagerrated the hypothesis by adding such expressions as "negligible mortality". If adult survival has declined, I, at least, am quite happy with that being part of "the sparrowhawk effect" and indeed it is what I would expect to find.
To put it simply, if one can find a hypothesis which appears to be consistent with all the evidence, both scientific and anecdotal, then that is the hypothesis which I would prefer to defend.
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