Nightingales in November (63 page)

Due to the abundant food on tap in towns and cities, many urban Peregrines will attempt to stay on their territories all
year round, but certainly those Peregrines at traditional rural sites in remote Scottish or Cumbrian fells, for example, may well be forced to relocate for the duration of the winter as their prey seeks more clement conditions elsewhere. Often these tough northern birds may opt to station themselves at, or close to estuaries, where bird numbers will have been steadily building up throughout the autumn. Originating from breeding areas as diverse as Siberia, northern Europe, the Russian Federation, Iceland, Greenland and north-east Canada, literally millions of wildfowl and waders are attracted to British estuaries each winter, thanks to a combination of our mild maritime climate and large tidal ranges. Feeding on the extensive areas of mud and saltmarsh around our coasts as the tides ebb and flow, large flocks of Teal, Dunlin and Knot will need to keep their eyes peeled if they are to avoid appearing on the diet of this most ruthless of avian predators.

Mid-November

Having been on the move ever since exchanging Europe for Africa a couple of months earlier, British-bred Nightingales should finally be arriving at the destination that will become their home until at least Christmas. Even before the wintering location of Nightingale OAD was revealed by analysis of the data from its geolocator, it had long been suspected that British Nightingales spend at least part of the winter in the countries of Senegal and The Gambia. Both situated in West Africa, the much larger country of Senegal is externally bounded by the Atlantic Ocean to the west, Mauritania to the north, Mali to the east and Guinea and Guinea-Bissau to the south. Senegal also almost entirely surrounds the Gambia – mainland Africa's smallest country, which apart from a short stretch of coastline bordering the
Atlantic Ocean, is a country consisting of little more than a long strip of land straddling the Gambia River.

Both Senegal and The Gambia are considered to be politically fairly stable, with the former's economy driven by exploiting and refining natural resources, while the latter's is dominated by farming, fishing and tourism. The region is characterised by a tropical climate, with a mostly pleasant to stifling heat throughout the year and well-defined wet and dry seasons. The vegetation close to the coast, in both countries, mostly consists of savanna woodland, thorny scrub, gallery forest and wetland, with The Gambia being particularly well known amongst the British birdwatching community, enticed by an impressively high avian checklist for such a small country. Highlights of a trip to The Gambia in the winter will include many species never likely to be seen in north-west Europe, together with a smattering of visitors only familiar to Britain during the summer months, such as Ospreys, Sandwich Terns, Reed Warblers and of course Nightingales. Just as in their English breeding grounds, when in Senegambia the Nightingales tend to stay true to their naturally skulking behaviour, preferring to keep low down in the tangled, thorny savanna scrub typifying their accommodation at this time of year.

Having completed most of their moult before they left British shores, any Nightingale glimpsed should be looking decidedly fresh as it settles down into a daily routine. The timing of the Nightingales' moult is thought to contrast starkly with that of the Cuckoos, which are only believed to carry out most of their moult when well ensconced on their Congolian wintering grounds. Due to the Cuckoos' effective disappearance from view for over 80% of the year, their moult is little understood, but it is believed that a proportion of adults may well replace at least some of their
body, flight and tail feathers before crossing into Africa. With the on-board satellite tags revealing that the Cuckoos move little at this time of year, it is reasonable to suggest they will be using this settled period to actively moult their remaining flight feathers. Cuckoos possess ten primaries, with ringers identifying the innermost primary (closest to the body) as P1, while the outermost feather is P10. These ten primaries are believed to moult in two series, with feathers P1 to P4 shed in descendant fashion – or away from the body, while P5 to P10 are moulted in an ascendant manner – or towards the body. To further complicate the issue, P5 to P10 moult in alternate fashion, giving a possible replacement sequence of 9-7-5-10-8-6. This regular alternation between growing and non-growing feathers should still presumably give the Cuckoos enough lift to both evade predators and forage effectively for food.

Amongst Britain's summer visitors there seems a distinct pattern, with those species migrating the furthest south generally delaying the majority of their moult until reaching their wintering grounds. Like the Cuckoo, this delayed moult will also occur with the Swallows currently entrenching their positions in and around South Africa's Western Cape. Despite the Swallows' moult having started around the beginning of October, or even earlier in a few cases, the entire process of replacing around 1,500 feathers may well take as long as five or six months. This protracted process could mean that the large outer primaries and tail feathers in many Swallows might still be actively growing upon their arrival back in Britain. For the Bewick's Swans currently bedding in to their wintering grounds, the moult of the adults' main flight feathers will already have been completed before they migrated south, leaving the exchange of the best
part of 25,000 body feathers to occur at a more leisurely rate right the way through to February.

During their marathon flight to Britain the Bewick's Swans will have lost considerable condition, with newly-arrived males weighing in at little more than 5kg and the females around a kilo lighter. In addition to sorting out their hierarchy within the flock, piling the lost weight back on will also be undertaken as a matter of some urgency. Certainly around the WWT Slimbridge reserve in Gloucestershire the swans are thought to initially prefer feeding on the rich improved pastures around the Severn Estuary. However, for those birds returning to the Ouse Washes in Cambridgeshire, or WWT Martin Mere up in Lancashire, the habitat of choice for putting the pounds back on will be a whole variety of arable fields. In those areas where feeding amongst arable crops is favoured, the numbers of Bewick's Swans tend to be initially highest on the stubble fields where the birds are presumably mopping up any spilt grain. But as soon as this resource starts to run out they will then move on to polishing off any waste from the remains of root crops left in the fields after harvesting. So nutritious are these varied foodstuffs, that scarcely a month after having returned back the males should have been able to quickly increase their weight back to a fighting fit 7kg, while the females will end up a touch lighter, at around a kilo less.

Tipping the scales at a mere 55g, or just under 1% of the weight of an average Bewick's Swan, the Waxwing's appetite could be considered even more prodigious in proportion to its size, which will primarily be due to the relatively poor nutritional value of many berries. Even in invasion years, such as the last one experienced in 2010, there still seem to
be surprisingly few birds reported south or west of a line drawn between the Isle of Man and London by the middle of November. This means that birdwatchers in cities such as Brighton and Bristol may just have to show a touch more patience yet before the first of these delightful invaders finally begin turning up on their doorsteps. Following the movement of close to 500 Waxwings that were individually colour-ringed by the Grampian and Orkney Ringing Groups in 2010, it appeared that many of the birds quickly relocated in southern England were individuals that had patently leap-frogged those colour-ringed Waxwings which had already moved down into northern England from their original ringing locations. Presumably, as the best food sources become steadily cleared out in a rolling wave across the country, ‘getting ahead' is the smart way to ensure access to fresh, untapped supplies.

While the Waxwings' winter diet is laid out for all to see, trying to elucidate exactly what food Puffins eat when dispersed out to sea is decidedly more difficult. What little information there is on their North Sea diet comes from 68 dead birds found washed up on beaches. In two-thirds of these, remains of gadoid fish (the fish family containing Cod, Herring and Pollack), Sprat, Goby, Three-spined and Fifteen-spined Sticklebacks and Snake Pipefish were all found. In just under half, the jaws of polychaete marine worms were found, and from one dead Puffin a squid beak was recovered. These remains could have been a slightly misleading representation of their true diet, however, as bones of fish, plates of pipefish, spines of sticklebacks and jaws of marine worms will undoubtedly persist in the stomachs of the birds longer than small, soft-bodied prey items. More accurate information on the Puffin's winter diet may have come from birds which were unfortunately snared by fishing long-lines between
Norway and Iceland. On analysing the stomach contents of 11 accidentally hooked birds, researchers found that they had been feeding on Glacier Lanternfish, squid and polychaete worms. While it is striking that marine invertebrates undoubtedly form at least part of many Puffins' winter diet, in addition to a whole variety of fish species, educated guesswork would suggest that when the birds are foraging below the surface, there may well be more of an opportunistic element to what they are catching rather than the precise targeting of any one species.