Where the cranes go (3)
After a more or less extended stopover at Lac du Der, the cranes continue their journey across France in stages, continuously or in large waves, depending on the weather, heading south-west to Les Landes in Aquitaine. There, centred on the Arjuzanx nature reserve, they make another stopover before crossing the Pyrenees. If the weather conditions are favourable, they can also cross them directly and fly to their destinations in the southwest and south of the Iberian Peninsula. Typically, however, they cross the Pyrenees through the valleys of Navarre and the westernmost valleys of Aragon to reach the Gallocanta lagoon, which has become a favourite resting place for the main stream of cranes flying in and out of Spain. The lagoon and its agricultural surroundings offer the animals the opportunity to rest undisturbed and feed up before continuing their migration south of the Iberian Central System (Sistema Central).
More than 30,000 cranes are counted during the peak migration periods at the end of October and mid-February, although concentrations of over 100,000 birds can also be seen on the faster homeward move to the breeding grounds (see table for the 2022/2023 season). The spectacle in spring is also one of the major ornithological - and acoustic - sights in Europe, attracting many visitors when the screaming flocks darken the sky as they fly in and out. Around 5,000-10,000 birds now use the lagoon as a wintering ground, meaning that cranes can also be seen regularly outside the main migration periods.
The Laguna de Gallocanta is something special: located on a plateau with a steppe-like character approx. 100 kilometres southwest of Zaragoza in the Spanish province of Aragon, it is the largest natural lake in Spain with an area of around 1900 hectares, about 7.5 km long and 2.5 km wide. The outflow-free basin is fed by rainwater and three small tributaries, meaning that the inflowing water is only lost through evaporation and causes the water to salinise. This in turn favours the presence of extensive banks and muddy areas, making the lagoon the largest saline wetland on the Iberian Peninsula and the best preserved in Western Europe. The freshwater springs ensure that there are reeds and bulrushes in some places. A paradise for wading birds and, of course, for cranes. Over 220 bird species have been counted in the area, whether nesting, wintering or migrating. However, the unpredictable amounts of rainwater lead to large fluctuations in the water level from year to year. In wet years, the lake can be huge. In drought years, it dries out completely in the hot summer months, and it has also been largely dry in some recent winters with little precipitation. Another extreme is that the lake is located at an altitude of 1,000 metres in one of the coldest regions of Spain - temperatures can drop to -15° C or even lower during frosty winter nights. On 12 January 2021, -25.4° C was measured in Bello.
For bird and nature lovers, there is a well-developed observation infrastructure with several observation towers offering views of the lagoon and the roosting places of the cranes in the salt lake (albeit at a very great distance). In addition, a number of rentable hides for nature photographers are maintained on the freshwater tributaries. As everywhere else, they are subject to strict regulations to protect the animals. The huts must be entered one hour before sunrise and may not be left during the day under any circumstances; this is only possible in the evening, one hour after sunset, when all the cranes have left. Quasi solitary confinement for 12, 13 or more hours. The intimate proximity and the special insights into the behaviour of the animals come at a price. The central information centre on the road connecting the villages of Tornos and Bello is open daily during the main crane season, otherwise at weekends, and is the starting point for information, documentation and guided tours of the reserve. A new "interpretation centre" in the village of Gallocanta is solely a bird museum.
The use of groundwater for agriculture and the increasingly low rainfall are leading to increased salinisation of the lake. This allows small brine shrimps to spread, which form the food base for a small population of pink flamingos. In 2021, there were breeding pairs in the lagoon for the first time. According to the ringing, some specimens come from the Camargue.
The wide, flat landscape in which the lagoon is embedded is framed by distant mountain ranges and is used intensively for agriculture. A few large pig farms are scattered in the surrounding area. The smell of manure is in the air. Large areas are mainly used to grow cereals. It is striking that the area, which has historically been sparsely populated, suffers from a pronounced rural exodus: There are many empty houses in the small villages, sometimes reminiscent of ghost towns in the USA with undergrowth blowing through the streets. Young people are drawn to the larger cities to earn a living. To counteract this and create jobs, the local authorities are trying to persuade companies to settle here, sometimes using dubious methods. According to Spanish media reports, Germany's largest pork producer Tönnies (cheap meat scandal 2020) is planning to build a huge, fully automated slaughterhouse and meat factory in the small town of Calamocha, perhaps 20 kilometres from the lagoon. From 2024, 10,000 pigs a day (!) are to be slaughtered on a former airfield site (the main operating base of the "Condor Legion" in 1937/38) and the Tönnies products produced will be sold throughout Spain and other EU countries. The mayor is delighted about 1,000 jobs and the economic benefits for Calamocha. The associated problems are less seen (groundwater pollution and over-fertilisation through liquid manure, antibiotic resistance, veterinary medicines in the environment, destruction of the cultural landscape and farmers' livelihoods). Local protest movements are unlikely in this sparsely populated area. Incidentally, the Spanish province of Teruel in the Aragón region is famous for its Jamón de Teruel with its own protected seal of origin.
The sparse population on the lagoon plateau ensures little light pollution. On clear nights, the sky offers a spectacle worth seeing and is ideal for astronomical observations and astrophotography. The previously described comet C2022E3(ZTF) was captured here in two wide-angle images in its celestial neighbourhood.
In the winter half-year, a look at an object that has been given the trivial name Christmas tree star cluster is a must. The associated star-forming region is catalogued as NGC 2264 (Cone Nebula) and describes a huge molecular complex in the constellation Unicorn (Monoceros) with dark clouds in the foreground. And there's something else that fits in with Christmas: A light comes into the world. At the tip of a column of gas and dust (yellow arrow), newly formed stars can be recognised. The second image shows a wide-angle section of the region with the well-known Rosette Nebula.
The complete album for the Laguna de Gallocanta is available here.
Back to the cranes: When they reach the Pyrenees from the north, the main migration crosses the mountains to Navarre, heading for Gallocanta. However, a small number fly to Spain via Irún on the Bay of Biscay and the Basque Country. These follow an old traditional route across Castile, which was the usual route until the first half of the 20th century: via Palencia (La Nava lagoon) to the dehesas and wetlands of Salamanca and Zamora. The drying up of most of the wetlands on this route (La Nava and others) led to a change of strategy, and in the 1970s the cranes began to migrate from Gallocanta through the centre of the peninsula.
We have also visited a small area of Zamora's wetlands, the Reserva Natural de Lagunas de Villafáfila nature reserve. Villafáfila is located in the Castilian-Leonese plateau at an altitude of around 625 metres, around 35 kilometres southwest of the provincial capital of Zamora. The surrounding area is similar to an open steppe landscape and is mainly farmed (cereals, it is on the edge of the "Tierra del Pan"). The narrower nature reserve consists of three large lakes and other smaller wetlands, which are located in a geological basin with no outlet. The gently undulating relief is interrupted by isolated groups of trees.
In addition to a comparatively modest number of resting and wintering cranes, however, the attraction is something else: The steppe-like scenery around these wetlands is home to around 2,000 great bustards, one of the world's largest colonies of this highly endangered species. With a body weight of up to 16 kg, the males are the heaviest birds that can fly. As Brandenburg has always been the stronghold of the Great Bustard in Germany, the majestic bird is also known as the Brandenburg Ostrich.
Villafáfila is aware of the conservation value of this rarity and has been running programmes to protect the animals and their habitat for decades. The reserve is a protected area for great bustards and lesser kestrels as part of the EU's LIFE environmental and climate protection programme.
Here, too, we have a very dark sky: the planets Venus and Mercury are reflected in a lagoon near Villafáfila in the early evening of 12 April 2023. For Mercury, the planet closest to the sun, the days in the first half of April were the only visibility slot in the evening sky of the year. The bright Venus is close to M45, an open star cluster also known as the Pleiades or "Seven Sisters".
More pictures of Great Bustards from Villafáfila and the Extremadura can be found here.
PHENOLOGY AND DISTRIBUTION OF THE COMMON CRANES (Grus grus) IN SPAIN 2022/2023 von José Antonio Román Álvarez (Coordinator)
Gobierno de Aragón, Centro de Interpretación de la Laguna de Gallocanta