Nightingales in November (21 page)

The movements of Chris the Cuckoo, showing four complete migration cycles between the autumn of 2011 and the spring of 2015.

Chris's migration in 2013, for example, seemed a typical year. Thought to have left on the evening of 1 April, Chris was next picked up on a juniper-covered slope, on a high plateau in the Atlas Mountains of Batna Province in northern Algeria. Having travelled a distance of 3,200km over both the semi-arid Sahel and then the Sahara Desert in around 60 hours, Chris was calculated to have flown at an average straight-line ground speed of 55km per hour! After a brief rest he was then thought to have moved on the night of 4 April, only to be picked up two days later, and 937km further north along the Italian and French border and close to the Mediterranean coast.

Amazingly, when Chris's route is compared with the other tracked Cuckoos emerging from the Sahara there seems a split, with some choosing their route into Europe via Italy, while others work their way towards Britain via the Iberian Peninsula. BTO researcher Chris Hewson has neatly summarised this split migration as ‘two routes, one destination'. To further complicate the picture, in 2012 and 2013 Chris returned via Italy, only to then try his
hand through Spain in 2014. Furthermore, when all the southbound routes leaving Britain in the summer are analysed alongside the northbound routes from Africa, it seems some Cuckoos will travel both ways through Italy, while others complete the northern and southern journeys though Spain. The most popular route of all, however, seems to be southward through Italy after breeding, only to then fly northward through Spain the following spring in a clockwise migration. And as a final variation, there seem to be Cuckoos like Chris, which appear to ‘pick and mix' their routes!

Those Cuckoos choosing the western route through the Iberian Peninsula at this stage may well be close to rubbing shoulders with the British-bound Nightingales, currently still feeding away in southern Spain and Portugal. Of the five Nightingales that had geolocators attached at Orlestone Forest in Kent in 2012 and which were then subsequently recovered, all of the birds were found to have arrived back during a tiny window between 12 April and 15 April 2013. So with the final leg of their journey from southern Europe estimated to take less than 24 hours, it's a safe assumption that the birds will still be busily tucking into a Mediterranean diet right up until the middle of the month.

The Blue Tit is the last of our chosen resident birds to begin nest building, and despite the construction being carried out solely by the female, the male will often accompany her on flights to collect the material. The foundations of the nest can be just of moss, but more commonly she will start by making a basic framework of dead grass, dry twigs or rootlets. Loose moss then tends to form the bulk of the nest,
which after two or three days of hard graft will have become 3 or 4cm deep. The female will then shape the cup, often in the corner of the nest, by constantly rotating her body. The final touches will include a lining of finer grasses, occasionally hair and a good number of feathers, but this last stage is only usually completed once she has begun laying her brood, which due to the large size of the clutch could take a week and a half to complete.

Early April will see the number of Bewick's Swans steadily rising across a few key estuaries and inland locations across Estonia and Latvia, as they begin to converge from other sites dotted along the Baltic coast. It seems the swans use these sites to feed on the large expanses of pondweed (
Potamogeton
species) and stoneworts, the latter being a peculiar algal group that to the untrained eye look more like underwater plants. This is obviously quite a departure from the diet of arable crops and grass pasture that many of the swans would have been consuming in Britain during winter. In fact, this choice of aquatic and marshland plants may well historically have been the swans' more traditional fare, before profound changes in agriculture here led to mass land drainage and an increase in arable land cultivation.

In a good Waxwing year, early April will still see a healthy number of birds feeding away in Britain and seemingly in no hurry to follow their colleagues back across the North Sea to their breeding grounds at more northerly latitudes. Those that have already left, however, should by now be moving on a broad front through FennoScandia, possibly following the retreating snow-melt, as they steadily work their way north to the huge taiga forests so characteristic of
Europe's northern reaches. Of course the ultimate breeding destination for these birds is anyone's guess, but of the 35 British-ringed Waxwings recovered abroad, seven came from each of Sweden, Norway, and Finland, and two from the Russian Federation. With the remaining 12 birds relocated on the near continent, and obviously actively still on migration, these recoveries give some idea of the potentially vast breeding range of this mercurial bird.

Mid-April

Making the last of their migratory hops, the Nightingale's song should be heard back in England by mid-April. Unlike many of our other summer visitors, which are usually first recorded making landfall at migration watchpoints, the first spring records of Nightingales are usually of birds pitching up straight back at their traditional nesting sites. The Nightingale is essentially a bird of dense thickets, within scrub and coppiced woodland of lowland England, and even when taking into account the worrying drop to around 4,500 singing males as recorded in the last census, the Nightingale has never been a common breeding British bird. They have never been known to breed in Ireland, Scotland or Yorkshire, for example, and despite these locations seemingly having plenty of suitable habitat, the slightly lower temperatures found further north might not be suitable for a bird that breeds at far higher densities in France and Spain.

Despite being a notoriously skulking bird throughout its entire stay in southern England, the dates of their arrival over the years have generally been easy to record as the males' first piece of business is to proclaim a territory with their beautiful, strident and ultimately ephemeral song. Singing mostly from low, dense undergrowth – although some individuals will occasionally sing out in the open – the
song is instantly arresting for its immense range and power. In one study where an individual male's song was analysed, it was shown to possess as many as 250 different musical phrases, compiled from a repertoire of 600 different basic sound units. When singing, these phrases were musically arranged in an infinite variety of sequences so that each performance could be considered a unique composition – once heard, never to be repeated. Many of the phrases are rich, liquid and bubbling, but are often interspersed with guttural croaks, unmusical chuckles and dramatic pauses, the latter at least giving the human listener a chance to catch their breath.

The fact that
we
derive enjoyment from listening to the bird's song is entirely incidental, as like all bird song, it is only ever produced for the ears of its own species, having evolved as a tool to both repel competing males while simultaneously drawing in the females. Commonly, male Nightingales will arrive back a touch earlier than the females, and as they jockey for position at sites they'll be familiar with from previous seasons, it will be the ‘repel' element of their song that is initially deployed. The main concentration of breeding Nightingales in Britain runs in a broad band through the counties of Suffolk, Essex, Kent and Sussex and each male holding a territory will be desperately keen to ensure that his trip all the way back from West Africa won't have been a wasted one.

While not a patch on the vocal ability of the Nightingale, with its undoubted talents lying principally in its migratory feats, the Swallow's song nevertheless also plays an important part in securing a mate for the breeding season. Like male Nightingales, the first Swallows to arrive at their traditional breeding sites will usually be the older males, who will then quickly proceed to lay claim to a breeding site of little more
than a few square metres, but which crucially contains either a nest or a potential nest site. Once this miniature territory has been secured, the male will then chase away any other males showing any interest in his location and back up this ownership with song and display. His song is a not unpleasant and rapid twittering, which often ends in a harsh rattle and the subtle variations within are thought to convey important information about the bird's age (or his experience) and his health (or attractiveness). The male's tail also plays an important part in securing a site and attracting a partner, and so during these early stages of the breeding season will frequently be spread wide to reveal the striking pattern of white spots.