The Spoonbill (Platalea leucorodia) has been well studied in Extremadura. Witness this blog itself, with regular reports on the monitoring of wintering and breeding birds. A particular feature of this species is the high proportion of colour-ringed birds seen in the field. It is also easy to obtain the complete back-stories of these tagged birds. The local birdwatching group SEO-Cáceres has therefore been systematically recording reports of ringed birds in Extremadura since 2008. Quite a lot of information has been built up by now, so the time seems due to take stock.
The culled information corresponds to 200 sightings of 102 different birds, the bulk dating from 2008 to 2011, together with a few from earlier years, the oldest from 2000. A special mention in dispatches must go to Sergio Mayordomo, responsible for 115 readings, and to a lesser extent Javier Prieta, with 51. A total of 21 collaborators have contributed in all (see final list).
The commonest case is a one-off sighting of a juvenile Spoonbill on autumn passage. Some birds, however, have been seen several times, with a maximum of 25 sightings of a French bird and 18 of a Dutch bird nesting in Cáceres. The Extremadura sightings were made in 23 different wetlands, with the following share-out: Alagón catchment area(102 records), Tiétar catchment area (68), south Cáceres (22) and Badajoz province(8). The sites with most sightings are Laguna de Galisteo (75) and Charco Salado, Casatejada (64). This reflects a clear bias towards the sites most visited by the most active members of SEO-Cáceres, since the Spoonbill's main locality in Extremadura, Los Canchales Reservoir, weighs in with only three records.
Origin of the ringed Spoonbills. Ringed birds seen in Extremadura come from five different countries. Two thirds of them were born in Holland; some way behind come birds from France, Spain (Andalucía) and Germany; with one Danish bird. The observed birds were born in 23 different colonies, 17 in northwest Europe (11 Holland, 3 France, 3 Germany and 1 Denmark), four in Spain and one in the Mediterranean (Camargue, France). The colonies accounting for most birds are Schiermonnikoog (Holland, 34 birds), Lago Grand Lieu (France, 12), Terschelling (Holland, 7) and Onderdijk (Holland, 7). The Andalusian birds were ringed in the saltmarshes of Odiel, Doñana (Pajarera and Casa Neves) and Cádiz Bay.
Age of the ringed Spoonbills. This is expressed in calendar years: i.e., the year of birth is the first calendar year, then clocking up an additional year each 1 January. Thus a bird born in 2008 would be in its fifth calendar year by 2012. For birds seen in more than one year their age counts again for each new sighting. In 93 cases the birds were only seen in one season, seven birds in two and two in three. The age-group accounting for most sightings was juveniles in their year of birth; 2nd and 3rd year sightings drop in number (most remain in the African wintering areas) with a slight upturn for 4th-year sightings (returning as adults), records tailing off thereafter. This tallies with this bird's mortality stats, 55% dying in their first year, 75% up to the age of 4 and 1.5% for adults (Luengo, 2011). The oldest bird in our trawl was in its 19th calendar year (18 years old); only 13% of the birds seen were older than 10.
Phenology of the ringed Spoonbills. The dates tend to vary from one colony to another so they have been broken down separately. The most numerous ringed birds are migrants from northern Europe. These birds turn up all year round (with a gap for December), with the heaviest passage from August to October, peaking in September and another smaller peak from February to April. Ringed breeding birds, for their part (six Andalusian and one Dutch), occupy their colonies from March to August, with peak sightings in May. Lastly, other birds born in Andalucía are seen only in summer, from June to August, as occurs in Los Canchales Reservoir, Badajoz (Emilio Costillo, pers. comm.).
Collaborators: Sergio Mayordomo, Javier Prieta, Eva Palacios, Florencio Carrero, Juan Manuel Brías, Rafael Parra, Manuel García del Rey, Dave Langlois, Raúl Guzmán, César Clemente, Javier Mahíllo, Vicente Risco, Javier Briz, Ángel Sánchez, Javier Gayo, Juan Carlos Paniagua, Marc Gálvez, José Guerra, Pedro Holgado, Manuel Iglesias, Mario Arcas and Luis Sanabria. Heartfelt thanks to the unsung Spoonbill ringers and other organisations that helped us fill in the back stories: Estación Biológica de Doñana, Otto Overdijk (Holland) and Loïc Marion (France).
- Luengo, A. 2011. La espátula común (Platalea leucorodia) en las marismas de Txingudi. Gobierno Vasco. Vitoria.