Background
The author writes that a "population-level change expected under a climate-warming scenario is a poleward shift in the distribution of organisms," and he says it is thus believed that "groups that do not shift their range margin consist of species that are declining, and would therefore be of particular management concern."

What was done
A few years earlier, Brommer (2004) had measured the range sizes and northern range margin locations of 116 bird species with a predominantly southern distribution in Finland; and of those species he notes that "the trend slope describing the change in their abundance for the period 1983-2005 was calculated for 53 species by Vaisanen (2006)," which resulted in "the largest dataset available of the long-term trends in population numbers of Finnish birds that is comparable across species, because it has both been gathered and analyzed using the same procedures." Last of all, and to complete the behavioral picture of the latter 53 species, Brommer (2008) determined the concomitant changes in their northern range margins.

What was learned
The Finnish bird specialist found that "species foraging in wet habitats had experienced strong range margin shifts as compared with other feeding ecologies." However, he said he found "no evidence that those feeding ecological groups that showed a relatively small shift in range margin had experienced low population growth or a population decline."

What it means
In discussing "the lack of correlation between the shift in range margin of the different feeding ecologies and the change in their mean abundance," Brommer states that "this finding is contrary to expected under a climate-change scenario, because, all else being equal, a clear range-margin shift should indicate a good capacity to track climatic change, which should result in a more positive trend in abundance if climate change is indeed the main driver of population-level change." Once again, therefore, another of the doom-and-gloom prognostications of the world's climate alarmists -- i.e., that species that cannot, or will not, move in synchrony with shifting climatic zones must decline in numbers and possibly go extinct -- has encountered another set of real-world data that fails to substantiate it.

References
Brommer, J.E. 2004. The range margins of northern birds shift polewards. Annales Zoologici Fennici 41: 391-397.

Vaisanen, R.A. 2006. Maalinnuston kannanvaihtelut Etela-ja Pohjois-Suomessa 1983-2005. Linnut-vuosikirja 2005: 83-98.