Friday 11 February 2011

HOW MANY CRANES WERE WINTERING IN SPAIN AND EXTREMADURA IN JANUARY 2011?

Quite honestly, we can't really answer this question because we have no formal counts to go on. We can, however, draw on figures from elsewhere to gain some sort of an idea. First of all we should remember that that the last Spanish Crane count (Grus grus) was held in December 2007, thanks to the effort of hundreds of collaborators. The results showed a significant increase in Spain's wintering population, with about 150,000 birds in the whole country and 80,000 in Extremadura. It also showed a tendency for the species to winter further north: Extremadura's share of the national total thus fell from 87% in 1980 to 53% in 2007. Nonetheless, due to the huge overall growth, Extremadura's population grew tenfold in this period (Prieta and Del Moral, 2008).

Coming back to today's situation, we have three main sources of information to gauge the current trend of the western European population. First of all there are the many counts of autumn migration carried out in the region of Central Hesse, Germany. In autumn 2010 no fewer than 210,000 cranes were counted up to 13 December (Kraft, 2010). Yet another all-time high, showing that the population has not yet peaked. Four autumns ago, in 2006, the figure for Hesse was 190,000 birds, with an estimate of 230,000 for the total European population. Simple extrapolation gives a current estimate of about 250,000 birds, one quarter of a million, which is not to be sniffed at. The second source of information comes from the equally numerous winter counts conducted in France (Deschartes, 2011). In January 2011 France clocked up another record figure: 108,000 cranes, topping the 103,000 figure for January 2010 and the 81,600 for January 2009. In 2011 the region of Aquitaine in southwest France accounted for the lion's share, with 66,000 cranes, followed by Champagne-Ardenne (20,200) and central France (15,000). The third source of information comes from Gallocanta Lake in Aragón, Spain, where regular counts are conducted. This year's January count of 18,500 cranes was slightly down on the mean figure of previous years (Heraldo.es).

These three sources of information are pretty much all we have to go on. Bearing in mind, however, that cranes also winter in Portugal, Morocco and Germany, about 130,000 cranes are likely to have wintered in Spain in 2010-2011, somewhat below the figure for 2007-2008 (the French estimate a figure of 124,000 cranes in Spain during the previous winter, January 2010). The dearth of information from Spain, except for Gallocanta and a roost or two elsewhere, rules out any estimate of the population in Extremadura. Nonetheless, everything seems to suggest that it was also down on the 80,000 figure for 2007. Who knows if for the first time in many centuries Extremadura has lost its status as Europe's biggest crane wintering area, losing out to Aquitaine in France? Food for thought: how much have we changed Europe in only two decades for a bird to change its winter range so radically?

Figures apart, another small reflection as the cranes begin to wing north again for spring. The crane spawns all sorts of conferences, festivals and presentations, mainly with a tourism bent. Curiously enough, however, we know very little about the resource we are selling because we don't know exactly how many cranes come here each winter. We can't hope to complete with the industrious French and German and the instant data they are capable of coming up with at the drop of a hat. But it still wouldn't be amiss to conduct at least some sort of joint count in Spain every few years.... Some there are, even on specialist forums, who have asked if cranes still winter in Extremadura (no comment).

Graph. Wintering Common Crane (Grus grus) Trend in France (taken from Dechartes & Le Roy, 2010).

Sources:
- Deschatres, Aurelien. 2011 (Francia). Message in the Forum grus-grus.
- Deschartes, A. & Le Roy, E. 2010. La grue cendrée en France. Migrations et hivernage - Saison 2009-2010 (Migration and Wintering of the Common Crane in France, 2009-2010) [
download].
- Kraft, Martin. 2010 (Germany). Message in the Forum grus-grus.
- Heraldo.es (Aragón). 4 Febuary 2011. [
read]
- Prieta, J. and Del Moral, J. C. 2008. La grulla común invernante en España. Población en 2007 y método de censo. SEO/BirdLife. Madrid. [
download]