Nightingales in November (55 page)

October

October is a month of huge change. As the vibrant green hues which dominated much of the countryside all summer rapidly retreat from view, the russets and reds that characterise this most autumnal of months will suddenly catch the eye. For birds, the breeding season will have been reduced to little more than a distant memory, which will differ markedly from some of our best known mammals, as Grey Seals and Red Deer move centre stage in the mating game. This is also a frenetic month for migration, as a huge variety of birds hone in on their winter destinations. Already one step ahead of an array of winter visitors heading to Britain, many of our resident birds, with their moults now completed, will be using this key month to re-establish territories for the colder and shorter days ahead.

Early October

When the seminal
Migration Atlas
was published in 2002, the whereabouts of British Cuckoos in winter was still considered largely a mystery. Up to this date only a single record of a British Cuckoo had ever been recovered south of the Sahara, belonging to a bird ringed as a nestling in Berkshire in 1928 and then subsequently shot in Cameroon in January 1930. It was the ornithological pioneer Reginald Moreau who speculated in 1972 that British-breeding Cuckoos must winter in Africa south of the equator. Recent ground-breaking work by the BTO tracking Cuckoos by satellite has not only confirmed firstly that Moreau was indeed correct, but furthermore transformed our knowledge of the movement of Cuckoos throughout the year. By additionally opening up this information to the public, thousands of interested bird enthusiasts have been able to follow the precise route taken by Chris and his band of brothers both online and in real time.

One of the main revelations when tracking the Cuckoos was the fact that the migrating birds opted for one of two routes, but still with only one final destination. Depending on whether the Cuckoos take the ‘Iberian route' or ‘Italian route' into Africa will then dictate where they rest up after crossing the Sahara. For those birds taking the more westerly route, Nigeria is seemingly most favoured as a staging point, while Chad was the country of choice for Cuckoos flying into Africa from further east. Despite occupying different countries, both populations of Cuckoos will still have been resting up in locations dominated by savanna. With this entire region's marked wet season running between April and October, the Cuckoos must have fed sufficiently well in order to now be fit enough to undertake the next leg of their mission, as they head off for the Congo. In the four years Chris the Cuckoo was
followed by satellite, 2011 could be considered a typical year. After a very settled couple of months in Chad, on 6 October Chris then suddenly upped sticks to fly almost entirely across the Central African Republic, before then pitching down 790km further south, and a distance of just 8km from the border with the country of the Congo. Poised on the edge of the Congo Basin, and just to the north of the main rainforest block, Chris's movements in that year seems to have followed a similar pattern to that of many of the other tracked Cuckoos in most years, whereby on arrival at the portal of Africa's greatest forest, the birds initially seem reluctant to rush in headlong, but instead prefer to proceed at a more leisurely pace.

For those Swallows that managed to successfully tame the Sahara Desert, there will be no resting on their laurels of a job well done, as they continue to push across into the sub-Saharan Sahelian belt, in the full knowledge they still have an awfully long way to go before finally reaching their wintering grounds. Moving through Mauritania and Mali, the precise route the Swallows take is unclear, but with recoveries of 35 British-ringed birds, representing a substantial proportion of all the British Swallows recovered south of the Sahara (but still north of their final destination) it seems that southern Nigeria figures prominently on the route. With most of these records coming from just north of the Gulf of Guinea in southern Nigeria, it would suggest that the Swallows, upon leaving the Sahel behind, will suddenly take a more easterly direction. Travelling quickly through Côte d'Ivoire, Ghana, Togo and Benin, the Swallows will then enter Nigeria as they converge on the region unattractively nicknamed the ‘armpit of Africa'. As per their northward journey in spring, the Swallows are most likely to be migrating in small, loose flocks, consisting of a few tens of birds feeding on the move, and are probably only likely to gather in any large numbers at key roosting sites.

By early October most of the adult Swallows will also have begun their annual moult, which due to the birds' need to fly efficiently throughout the entire journey, will be a long and drawn-out process taking potentially up to half the year. Starting with the body and wings, the first feathers to be replaced will come from the back and rump, as their glossy blue-black upperparts suddenly become far duller and flecked with white. Only when halfway through the protracted wing moult will the tail feathers finally begin to be replaced. The timing of the adults' moult also differs slightly to that of the juveniles, which usually wait until they have arrived in their winter quarters before instigating the change that will ultimately see them transformed into adults.

As both the Swallows and Cuckoos make a beeline for the Congo Basin, the Nightingales will have already taken their foot well off the accelerator pedal following their initial leap across the Mediterranean. Believed to be slowly working their way south along the Atlantic coastal desert of West Africa in early October, the Nightingales will be taking advantage of this gentle rate of progress as an opportunity to feed on the way. The few human inhabitants living in this region are likely to be either nomadic herdsmen or fishermen, so that despite much of this coastal vegetation having been heavily overgrazed, the habitat should still be sufficiently intact for the Nightingales to remain true to their skulking character as they forage for invertebrates on the move.

While Estonia and the Gulf of Finland are likely to hold a high proportion of the European Bewick's Swans at this
time, other individuals will have travelled even further south to take advantage of a variety of inland and coastal sites in Lithuania, with the Nemunas Delta being considered the most important site. Protected under the Ramsar Convention, this globally important wetland on the Baltic coast is considered by BirdLife to be the most critical bird area in the whole of the country - representing a crucial layover for millions of migratory birds each year. Formed as the River Neman reaches the Baltic Sea, the delta consists of a maze of river branches and canals which criss-cross to form polders and wetlands, in turn creating the perfect habitat for the swans to rest and feed after their long journey. Having completed their wing moult well before they left their breeding grounds, the adults should by now also have replaced their tail feathers. The body plumage, however, will continue to be replaced throughout the entire winter, and in all probability will not be completed until the birds are preparing to leave their wintering grounds in February of the following year.

As the Bewick's Swans recover condition before undertaking the last leg to Britain, the sheer number of Waxwings in southern Scandinavia during an invasion year will cause the entire berry crop to be rapidly stripped. The scarcity of food will then give the hungry birds little option other than to either make the short trip across to Denmark through the Strait of Øresund or make the longer sea crossing over the North Sea to take advantage of the plentiful berry supplies on offer in Britain. With autumn now proceeding at a brisk pace, the Waxwings may not be the only continental European breeding birds being pushed towards Britain.

The probable autumnal migration routes of Waxwings between their breeding grounds in northern Europe and their wintering grounds in Britain during an invasion year.