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Message: <blockquote data-quote="KnockerNorton" data-source="post: 1684995" data-attributes="member: 66452">Not in Britain - Goshawks and Peregrines habitually hunt Sparrowhawks. On the Continent, Eagle Owls are the top avian predator (and here, where they're introduced).Indeed, but the implication is that if they have been predated, then they're not going to be there again. There were lots of Water Voles until Mink ate them.Nobody is discounting 'human factors'. Indeed, they're at the root of it through habitat fragmentation, removal of top predators, and countless other interventions. But it's not really much use to say "I feel that x,y,z is more important", as Chriskten says. There is plenty of evidence out there that suggests that predation is quite important too. Another thing is that different factors change in importance at different times. So food is not an issue in spring, whereas predation can be (by taking breeding adults). Predation is probably not an issue in summer (lots of surplus juvs), whereas food can be (it soon runs out).As some of the previous posts point out, this is true only to a point. In the Danish study, Sparrowhawks were dependent on Blackbirds but not Song Thrushes. Whereas Song Thrushes may have been very heavily dependent on Sparrowhawks (or a lack of them). The key thing to bear in mind is that predation pressure is not equal for all species, as not all species occur in the same numbers. Predation rates of 25% a year doesn't matter if your population is large, as there are still plenty left to breed and make good the losses. But if your population is small, and is under pressure from other areas too, then predation can be very important indeed. There are plenty of cases where this is obvious (predation at tern and wader colonies etc).</blockquote>

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