Nightingales in November (54 page)

While the Lapwings continue to arrive in their winter quarters, the Bewick's Swans in an average year should by now be leaving any pre-migratory sites in and around the Pechora Delta of Arctic Russia as they head for north-west Europe. The swans are believed to take a relatively narrow migration flyway as they follow the north Russian coastline west to the White Sea, before then heading south-west across Karelia, via Lakes Onega and Ladoga, and on to the Baltic coast. Satellite tracking of the swans' migration by Dutch scientists in 1998 and by the WWT in 2003 has also revealed that the autumn passage occurs much more rapidly than the spring migration, with Bewick's commonly only taking one proper rest. For example, five birds carrying transmitters in 1998 were recorded flying virtually non-stop to the Baltic countries, a distance of anywhere between 1,800 and 2,300km, with only brief stops along the way, probably to drink. Three other swans tracked during the same migration also stopped for just a few days at the White Sea, making it probably a far less important stopover site in autumn than spring, with two of these birds then also briefly recorded resting up in the Gulf of Finland, just west of St Petersburg and off Estonia's northern coast. Three other swans tracked by the WWT in 2003 were also recorded to fly directly from the Pechora Delta to the Baltic region,
with the journey taking just two days. Possible reasons why this migration may occur more rapidly than their return journey include the birds being held up by icy conditions further north in spring. The swans also need more time to feed intensively in preparation for the rigours of the breeding season ahead. While the number of swans seen in Estonia during the autumn passage is much lower than recorded in spring, one site that seems particularly important at this time of year is Lake Peipus, a huge freshwater lake straddling the Estonian and Russian border. Covering over 3,500km, and ranked the fifth largest in Europe, this lake is now considered a remnant of a much larger body of water dating back to at least the last ice age. Averaging a depth of just seven metres ensures the lake quickly warms up but also rapidly cools down, with the result that it can be frozen for over five months of the year. This shallow nature not only produces particularly rich feeding opportunities but also plenty of suitable resting areas for the swans needing somewhere safe to recover from the first and longest leg of their journey. Sightings of ringed birds on the lake suggest that the swans may well spend up to a couple of weeks feeding away on the abundant pondweeds before then finally moving on to either the Netherlands or Britain.

As Waxwing numbers continue to build in northern Europe in an invasion year, resulting in a surge down to southern Sweden, the majority of British-breeding Cuckoos will still be some 5,000km away due south in either Chad or Nigeria. The moult is complex in Cuckoos and still not clearly understood, but while a partial moult of body feathers may occur as early as June and July, most, if not all, of the wing and tail feathers will not be replaced until well after the birds have arrived in Africa. This should mean that at this stage the birds won't just be feeding to recover condition after their
migration across the Sahara but also to power the growth of fresh feathers. The habitat that the Cuckoos have plumped for in Chad and Nigeria may well be very similar to that found in Manda National Park, a reserve close to the border with the Central African Republic, and near to where Chris the Cuckoo has stopped to feed on at least two of his southerly migrations. Consisting of woodland-savanna and grassy floodplain, with patchy stands of dense woodland and fringing vegetation, the Cuckoos here may also be rubbing shoulders with the occasional pack of African Wild Dogs and even wild Ostriches which are also resident in this part of Africa.

It was the pioneering individual ‘OAD' that first revealed that the Western Sahara, in north-west Africa, may well figure prominently as the first landfall for British Nightingales freshly arrived from southern Europe. Bordered by the Atlantic Ocean to the west, the territory of the Western Sahara consists mostly of desert flatlands, making the Cuckoo habitat in southern Chad and Nigeria seem positively lush in comparison. In fact with no permanent streams, Western Sahara encompasses some of the most arid and inhospitable terrain on the planet. The sparse greenery that is present seems to be largely confined to the Atlantic coastal desert habitat, a narrow strip of land fringing most of Western Sahara's 1,110km coastline which continues south all the way into Mauritania. Despite the climate being extremely hot and arid here, with only low amounts of episodic rainfall, the mists blown in from the Atlantic help maintain a range of succulent shrubs and arid-adapted plants along this ‘green corridor', and also permit the growth of lichens both on the bare ground and on the vascular plants themselves. Classified as part of the Sahara Regional Transition Zone, this ecoregion is far more vegetated than most of the Sahara Desert and also forms part of the East Atlantic Flyway migration route, a
corridor enabling a whole range of bird species to travel between Europe and Africa.

In contrast to migratory species like the Bewick's Swan, Nightingale and Cuckoo, which tend to travel along a prescribed migration route, the movement of Puffins after the breeding season is considered more of a dispersal, as they radiate out to sea. Until recently it was thought that the Puffin populations from east and west Britain were spatially segregated, both during and after the breeding season. However, thanks to the work of Mike Harris's team with geolocators on Puffins from the Isle of May, off Scotland's east coast, this is now thought not to be the case. Three-quarters of the birds followed from this colony were seen to carry out a major excursion from the North Sea into the Atlantic at the end of the breeding season, leading to the conclusion that there must after all be some mixing of Puffins from eastern and western breeding colonies during the winter. Recent research also indicates that the rich fishing waters around the Faroe Islands may well be an important overwintering location for many British-breeding Puffins. Consisting of 18 major islands and situated approximately halfway between Norway and Iceland, this remote archipelago lies some 320km north-northwest of Great Britain. Despite its diminutive size, the rugged rocky islands and the rich surrounding seas are able to hold over half a million pairs of breeding Puffins each summer. Mixing with their Faroese cousins, British-breeding Puffins will probably be spread out, possibly in small, scattered groups as they divide their time between fishing and roosting.

In contrast to a possibly large number of our breeding Puffins feeding just south of the Arctic Circle, the Swallows which
summered in Britain will be streaming towards the equator by late September. Wanting to avoid a long sea crossing, many Swallows will opt for entering Africa from southern Europe via the Strait of Gibraltar. At just 14km in width, this narrow crossing, which also connects the Atlantic Ocean to the Mediterranean Sea, is not just an incredibly important shipping lane with huge historical significance, but is also arguably the most important bird migration route between Africa and Europe. Used by hundreds of thousands of kites, storks and buzzards each spring and autumn, the narrow strait minimises the distance that these large soaring birds need to spend above the sea. Unlike land, water is incapable of producing thermals, so large birds will need to wait for sufficient lift to get them high enough before resorting to the far more energetic technique of actively flapping across the strait until they can once again access the thermals over dry land. While Swallows will have more than enough energy to keep them flapping the whole way, even across the wider sections, the lack of food available for them to forage over the sea may mean that crossing at the narrowest point will dip least into their limited reserves.

Upon reaching North Africa there may then be a brief opportunity for the Swallows to feed in the fertile crescent of land bathed by the Mediterranean Sea before pushing on inland, over the Atlas Mountains and into the Sahara Desert. Taking on 1,500km of the world's greatest desert on a broad front, mostly west of the Greenwich meridian, will once again provide very few opportunities to feed, as they cross the desert interiors of Morocco and Algeria, before then taking on the equally arid countries of Mauritania and Mali further south. Most small migrants are thought to use an intermittent migration strategy which involves resting in the desert during the daytime, migrating at night and then refuelling at any oases encountered along the way. Swallows are, however, thought to continue their day-flying strategy, while taking advantage of any feeding opportunities that may prevail along the way. One such oasis that a number of
trans-Saharan migrants will pass through can be found at Ouadâne, situated on the southern edge of the Adrar Plateau. A World Heritage Site, the old town is situated close to an oasis surrounded by Date Palms and Sorghum, which will undoubtedly provide very welcome feeding opportunities for any desperately hungry and thirsty Swallows which may not have fed since leaving North Africa.