Fig. 3.

Analyses in Fig. 2 were repeated with an analogous, unpublished, null model provided by Beale et al. With the new null distributions, models with real data were better than expected by chance 55% of the time (instead of 32% in Beale et al.). To formally examine the null hypothesis (H₀) that climate does not drive bird distributions in Europe, we combined significance values for all species using Fisher's exact test (7). When P values approach 0, it leads to rejection of the null hypothesis, thus supporting the alternative hypothesis of a statistically significant relationship between species distributions and climate. Here, the combination of P values yielded an overall P < 0.0001. Under H₀, the frequency distribution of P values should also be uniform between 0 and 1, a condition that is not met with these data.