ATLANTIC DEPRESSIONS AND WIND-BLOWN COASTAL BIRDS

Extremadura's last winter from December 2011 to March 2012 recorded an all-time low rainfall since records began. Luckily, April was fairly wet, saving a spring that was shaping up as dire. A succession of depressions swept in from the Atlantic in April 2012, rounded out by an explosive cyclogenesis on the 25th. The associated winds might have been responsible for the appearance in Extremadura of coastal migratory birds in the second half of April and first part of May. The phenomenon of coastal birds swept inland by winds usually occurs in winter, resulting in red-letter species for Extremadura like Great Northern and Black Throated Divers, Great Skua, Storm Petrel and Madeiran Storm Petrel. Spring episodes are pretty rare.

Common Tern (Sterna hirundo). Adult at Valdecañas Reservoir, Cáceres, on 12.07.11 (Ángel Sánchez). 

The standout example this spring has been the Common Tern (Sterna hirundo). Our April summary reports sightings in three different reservoirs, with maximums of ten birds at Guadiloba on 26 April (S. McAvoy/Birdwatch Ireland and G. Schreur), seven at Ahigal (A. Pacheco) and twelve at Portaje on 27 April(S. Mayordomo). On all occasions they were accompanied by Little Terns and Whiskered Terns, which may also have been wind driven but are more normal passage drop-ins inland. Subsequent visits to the same places did not turn up any Common Tern sightings. This brief influx, albeit modest, is the biggest recorded to date in Extremadura. In the eleven-year period running from 1998 to 2008 there were only five sightings of one or two Common Terms in April-May (without counting the breeding birds in Valdecañas Reservoir, the most recent in 2011).

Some coastal waders also turned up in greater-than-usual numbers in spring 2012, though relating these to the April storms is perhaps more a bit more fanciful. These included the Whimbrel (Numenius phaeopus), a very scarce but regular spring migrant in Extremadura. From 1998 to 2008 there were thirty sightings, the biggest being a flock of eight. In April 2012 it was seen in at least five sites, including the biggest flock ever recorded in Extremadura: 27 birds at Arrocampo Reservoir on 22 April (J. Julián). Much the same goes for the Sanderling (Calidris alba), with only 14 records involving 19 birds from 1998 to 2008 but with April 2012 records of six birds in three different places. That said, waders seem to be turning up in bigger numbers than usual in Extremadura this spring, this trend even continuing throughout May.