Monday, 26 November 2012

HERONS IN SPAIN AND EXTREMADURA. SURVEYS 2011.

SEO/BirdLife has published a monograph of the census results of breeding and wintering herons carried out in Spain in 2011 (Garrido et al. 2012). Although Extremadura is not renowned for its wetlands, rather the opposite, it ranks second after Andalusia, in terms of importance for wintering birds (32 900, 14% of Spain) and third in terms of breeding pairs (9,900 pairs, 15% of Spain, in 84 locations).

As a family, the herons are increasing and most of the studied species show increases in Spain. The night heron (Nycticorax Nycticorax) has risen from 1,300 in 1986 to 5,400 pairs in 2011. The squacco heron (Ardeolla ralloides) from 200 in 1980 to 2100 pairs in 2011. Grey heron (Ardea cinerea) from 168 in 1950 to 7,000 pairs in 2011. The purple heron (Ardea purpurea) from 2,000 in 1997-2003 to 5,400 pairs in 2011. The bittern (Botaurus stellaris) from 26 pairs in 1980 to 41 in 2011. And the great white egret (Egretta alba), which began breeding in 1997 in the Ebro Delta has gone to 53 pairs in 2011. By contrast decreases were detected in the little egret (Egretta garzetta), with a small drop in the last ten years, resulting in 2011 (9350 pairs) against 1990 figures (7,600 pairs) but lower than 2002 (10,400). The most abundant species is the only one who has suffered a significant decrease. We talked about the cattle egret (Bubulcus ibis), down from 70,000 pairs in 1989 to 40,000 in 2011. This is a species that has incresed during the twentieth century and whose population can fluctuate greatly depending on local conditions. Experts say that some species show strong expansions, then suffer a decline after which the population is consolidated and stabilized.

 
 
 

Garrido, J. R., Molina, B. y del Moral, J. C. (Eds). 2012. Las garzas en España. Población reproductora e invernante en 2010-2011 y método de censo. SEO/BirdLife. Madrid.