The most frequent GBS Birds

["Philip Veerman" <>]

Hi All,

 

Martin has written a page in the latest Gang gang about the most frequently recorded birds from the GBS. There is no doubt that all information given there is true and reasonable (although not complete in its explanation). I would point out though that the information and these ideas are not new or original, apart from now covering 28 years. Sadly, yet again predictably his paper fails to cite prior sources. Ideas about comparing the R & F values of particular species is given in the GBS Report, in particular on pages 40 to 46. The point that Martin missed though is that there is a hole in the connection he makes. The comparison of R & F values would make a tight bit of analysis if every site was surveyed for every week, but the GBS is far from achieving that. This is why figure 7 of the GBS Report is essential in thinking about this connection. Obviously sites only surveyed for example during the summer are unlikely to record the winter migrants (and vice versa). Sites only surveyed for less than half of the year have a far greater impact on restricting the values of F than R. This makes a huge difference in the connection between these two parameters. Beyond that, of course the survey method is going to generate higher F values than R values, which is the basic point Martin was making. 

 

Philip