Yesterday, a doctoral thesis written by Luis José Salaverri was completed at the Faculty of Biology of the University of Santiago de Compostela. José Guitián, Mar Sobral and myself were the proud supervisors attending the lecture. The academic board was composed by Eduardo de Juana, Alberto Velando, Paola Laiolo, Pedro Galán and Jesús Domínguez.
The thesis studies the changes occurred in the avian communities of Galicia (NW Spain) related to major environmental drivers such as climate change and land abandonment. Galicia is located in between the Atlantic and the Mediterranean biogeographical regions and in the last decades it has experienced dramatic modifications in its landscape caused principally by rural depopulation and the abandonment of traditional farming practices.
The thesis is divided in four chapters that assess, respectively: (1) The trends in abundance and richness of wintering waterbird communities over a period of 20 years (1990 – 2009) in the main 19 coastal wetlands of Galicia and the Cantabrian; (2) The shift in the distribution range of nesting southern (i.e., Mediterranean) bird species in Galicia over 19 years (1979 – 1998); (3) The effect of agricultural abandonment on the abundance and richness of bird communities across the landscape that surrounds rural settlements; (iv) The effect of use and woodland fragment characteristics on the bird communities of ancient sweet chestnut (Castanea sativa) woodlands.
- The abundance and richness of wintering waterbirds showed a positive trend in the study area, but these trends were not consistent across localities. Particularly, there was a tendency for western localities to show a negative trend and for eastern localities to show a positive one.
- Between 1979 and 1998 southern bird species in Galicia have moved
northwards at an average rate of 0.8 km per year, a result that is in accordance with expectations from climate change. The two species that showed the largest northward shift were the white stork (Ciconia ciconia) and the corn bunting (Emberiza calandra).
- Rural settlements in Galicia act as bird diversity hotspots, as the diversity and abundance of birds decreases with distance from the village. Agricultural abandonment had a negative impact on the abundance and richness of bird communities affecting mainly finches (Fringillidae) and transaharian migrants.
- The intensity of use of chestnut woodlands had no influence on the abundance and the composition of bird communities. The singularity of the avian community of chestnut woodlands, as compared with the landscape matrix, increased with mean tree size.