Nightingales in November

by Mike Dilger

  By the time the Swallows cross into Britain, most will have also completed their long, protracted moult, which will have begun as long as six months ago. At this stage the males can easily be picked out by the intense blue plumage covering their crown, mantle, rump and long, elegant tail streamers. The long outer tail-feathers of the males are much more than just a superfluous fashion statement and will soon play an important part in attracting any prospective females at the breeding sites. A higher proportion of the early birds tend to be male, with the females generally entering UK airspace a few days later. Most adult Swallows are also highly faithful to breeding sites, with those males returning ahead of the competition being in pole position to secure the best nesting sites by the time the females arrive.

  As the Swallows begin to zero in on their tried and tested breeding locations, the female Tawny’s patience and devotion should now finally be paying off, as chick number one wins the first of many battles by successfully managing to emerge from its egg. Despite a gap of 56 to 64 hours between when each egg was laid, in reality the chicks hatch pretty close to one another time-wise, with the chick from the final egg the only one to often emerge substantially later than the others. Tawny Owl chicks hatch in a relatively undeveloped state and initially are blind and unable to regulate their own body temperature. Arriving into the world in such a helpless state means that these scantily-clad balls of down will for some considerable time be entirely dependent on the life support system that is their parents.

  The white egg tooth adhered to the top of the chicks’ bill usually drops off within the first week, and during these early stages they will spend most of their time nestled under the brooding female, simply keeping warm. Initially, the chicks are unable to beg for food, but will take small morsels when offered. As their eyes are closed, it’s thought they are only able to sense food when it brushes against the bristles at the base of their bill, giving the signal to ‘open up’. With the female carefully tending to the chicks’ every need in the nest, it will be the male’s responsibility to find enough food to provision his new family. Announcing his arrival with a call, most of the prey is delivered to the nest at night and he will usually alight only long enough to drop off the food. At first their food demands are minimal, but as the chicks begin to grow and their appetites increase exponentially, their father may then also be pressed into catching food during daylight hours too.

  By early April, most female Kingfishers in southern Britain will have begun to lay their first of possibly two or even three clutches deep in their subterranean nest chamber. Laying an egg a day, most clutches will consist of six or seven shiny, white and round eggs, measuring around 23mm across and weighing in at marginally more than a 1p coin. Only once the clutch is complete will incubation begin in earnest, and despite the female putting in longer shifts both parents will take their turn. When not incubating, the other bird in the pair will spend its ‘downtime’ either patrolling the territory or fishing.

  From the moment the birds start incubating, the river tends to instantly become much quieter, but both birds will still defend their patch, and should any intruder be discovered during this period the incumbents will explode into defensive action. Exactly this type of territorial dispute was filmed by wildlife cameraman Charlie Hamilton James for his Natural World film entitled My Halcyon River. Airing on the BBC in 2002, one particular sequence has surely become one of the most memorable moments of wild behaviour ever filmed in Britain. Charlie was busy filming his local Kingfishers and managed to capture the moment that a trespassing female was caught in his resident pair’s territory. Upon spotting the trespassing bird, the resident female immediately went into attack mode and, as neither bird backed down, both quickly ended up locked in mortal combat as they tried to drown each other. While this commotion was carrying on, an American Mink then suddenly dashed out of the waterside vegetation, and into Charlie’s shot, before grabbing one of the Kingfishers, which was immediately dispatched and presumably stashed before the mink returned for Kingfisher number two. In the meantime, the surviving Kingfisher, which fortuitously happened to be the resident female, had managed to scrabble out of the water and to safety above ground. Even if we think it’s a quiet time for the Kingfishers, it may in fact be anything but!

  As Peregrine eggs usually take between 31 and 33 days to hatch, early April should see many urban Peregrine pairs around halfway through the incubation process. As the female carries out most of the incubating duties, the male will also need to hunt for his mate during this period. Flying in with prey, he will then either execute an aerial food pass with her or bring the item to one of her favourite perches away from the nest site. Peregrine supremo Derek Ratcliffe thought that a high proportion of kills at this time, certainly in rural nest sites, were made by the male early in the morning, and while the female fed, he would then take a turn to incubate the eggs. During the whole incubation process the only time that the eggs are believed to be left uncovered is when the female briefly leaves to preen, defecate or even hunt, if the male is either not pulling his weight or weather conditions are making catching prey difficult.

  After the essential prerequisites of courtship, scrape adornment and copulation, the female Lapwing will be free to begin laying, with four eggs being the most common clutch size. Taking anywhere from four to eight days to produce her clutch, the distinctive eggs are ‘pyriform’ or pear-shaped, and invariably arranged so that the distinctly pointed ends face inwards. Unlike the eggs of Tawny Owls and Robins, which due to their pale, unspotted nature would stand out like a sore thumb in open country, the Lapwing’s clutch has evolved to blend in with the immediate surroundings. This effort to actively camouflage the clutch is helped by the eggs’ background pigment of pale brown or clay, which is then furnished with numerous black blotches, streaks and spots to break up their outline. Weighing in at around 25g each, the eggs are proportionately large for the size of the bird, meaning a clutch of four could potentially weigh close to 40% of the female’s entire body weight – a huge physical investment on her part.

  For Lapwings, incubation will only begin when the last egg is laid, and in common with birds as diverse as Peregrines and Kingfishers, even though both sexes are able to incubate, it’s the female that takes both the larger share during the day, and the entire night session. For those females that plumped for a polygynous male, their incubating share may be even greater due to his attentions being pulled in at least one other direction.

  With the nest complete, and mating largely dispensed with, the female Robin should also now be laying her clutch. Only visiting the nest for short periods at this stage, an egg will be deposited each day, with the time slot between 6am and 8am most favoured. Robin eggs are mostly white and speckled with small reddish-brown spots, although the background colour can occasionally be a pale blue or yellow. Each female Robin does seem to have inherited just one egg colour, however, with the result that all eggs in the same clutch should look similar. Like the Tawny Owl, and in fact most cavity-nesting species, the Robin’s eggs do not of course need to be coloured for camouflage. Amongst British Robins, five appears to be the most common clutch size, although four, six, seven and very occasionally even more have been reported. Interestingly, clutches of six seem to be more common amongst Scottish Robins in May and June, and may be due to the longer daylight hours, giving the parents more time to forage for that extra beak. As soon as the final egg is laid, the female will then be intent on keeping a very low profile for the following 14 to 16 days of incubation, in order to avoid any unwanted attention from a whole variety of hungry predators.

  Having only just built up the confidence to land at their nesting colonies, the first Puffin eggs will probably not appear for at least another three weeks yet. Initially very nervous on land, the vanguard often form ‘clubs’ on exposed rocks, which the birds will use as staging posts while keeping a collective eye out for predators. Spending the breeding season in a packed nesting colony means that Puffins have ha
d to evolve a whole array of ritualised behaviours to convey messages to both their mate and immediate neighbours, one of which is the ‘post-landing gesture’. This behaviour involves placing their body in a more horizontal position with their legs slightly bent and wings held aloft and above their back; this is thought to be deployed by any bird that has just flown in to appease all the other surrounding Puffins.

  Unlike other colonial auks like Guillemots and Razorbills, which are primarily ledge nesters, the Puffins prefer the sanctuary of nesting underground in burrows. Upon arrival at the colony, and with their confidence boosted by their membership of the ‘club’, they will then start briefly peeling away in order to conduct mini inspections of any nearby burrows. This ‘branching out’ is conducted in the full knowledge that if any danger is sensed, they will still be able to either quickly take to the air or run back to the club. Those Puffins that have previously bred within the colony will typically first check out the very same burrow they will have used in previous years. At thriving puffinries the competition for nesting locations can be intense, with experienced birds fiercely defending what they perceive to be their own property. Any returning owner coming back to a previously occupied burrow, only to find a prospector sniffing around, will swiftly switch into full eviction mode. Puffing itself up and half spreading its wings, the aggressor will open its beak in a menacing gape, and if this doesn’t have the desired effect, it will quickly pick a fight. Using its bill and feet as the main weapons, any ensuing scrap is often short and sharp, leading to the possession of the contested burrow being quickly resolved once and for all. Victory complete, the conquering Puffin will then declare his site ownership to all onlookers with a ‘pelican walk’, which involves standing upright, with his bill pressed to his breast feathers, while conducting a slow, exaggerated walk.

  As the Puffins reacquaint themselves with their burrows, it will also be crunch time for the Cuckoos, which after feeding well in the Ivory Coast will be able to delay their crossing of the Sahara Desert no longer. Until his unfortunate demise in the summer of 2015 Chris the Cuckoo was successfully followed on his northward journey by satellite on three occasions. During those three migrations his departure point for the Sahara, and all points further north, has varied, being twice from Ivory Coast and once from adjacent Ghana. However, he always left within a small time-window of ten days – with the first of his ‘desert days’ falling each year between 1 April and 10 April. Chris’s departure dates also seem to tally with the movements of many of the other Cuckoos tracked as part of the BTO’s research programme.

  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 o
f 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.