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Message: <blockquote data-quote="KnockerNorton" data-source="post: 1684763" data-attributes="member: 66452">I'm afraid that you're mistaken. These 'studies' I mention are from some of the longest-running, detailed studies of bird demographics in the World, and are published in the top peer-reviewed ornithological journals:<a href="http://www3.interscience.wiley.com/journal/119107299/abstract?CRETRY=1&SRETRY=0" target="_blank">http://www3.interscience.wiley.com/journal/119107299/abstract?CRETRY=1&SRETRY=0</a><a href="http://www.springerlink.com/content/kj6cfjvvekt5htvy/" target="_blank">http://www.springerlink.com/content/kj6cfjvvekt5htvy/</a><a href="http://www.ingentaconnect.com/content/bsc/janim/2009/00000078/00000005/art00022" target="_blank">http://www.ingentaconnect.com/content/bsc/janim/2009/00000078/00000005/art00022</a>Also see Perrins, C.M. & Geer, T.A. (1980) The effect of. Sparrowhawks on tit populations. Ardea, 68,. 133–142.Page 29 of the report you linked mentions one of these studies, and acknowledges the high predation rate. But it was selective in what studies it actually mentioned. It only quotes two studies when there are many more that show conflicting results. The report quotes peer-reviewed studies, but is not peer-reviewed itself. Therefore, it is an opinion piece and not an objective review. Personally, I think it is far too conservative, and the obvious reason is that the RSPB does not want to give any ammunition to e.g. Songbird Survival. It is probably aimed at lobbying against the lobbying for raptor control. I wouldn't rely on either organisation for an objective assessment of the evidence!The Denmark studies shshow the type of interaction that can occur with predators and prey - it's often complicated. In a current long-running study of a red-listed species (not yet published), the main cause of 'territory failure' (failure to produce young) is from predation of adults in spring - with all evidence pointing to Sparrowhawk predation. So there is a distinction between predation effects on abundant, high-density species (like Blue Tit or Blackbird) and rarer species in the same area (like Willow Tit or Song Thrush). So the effect of Sparrowhawks is not the same for all of their prey species, as these species have different ecologies. Sparrowhawks can also affect behaviour in more subtle ways: Jablonski, P.G. & Lee, S.D. (2000) Foraging sites of Marsh Tits (Parus palustris) in presence and absence of hawks in mixed-species flocks in Korea. Ornis Fennica 77: 39 - 42.</blockquote>

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