Nightingales in November

by Mike Dilger

  A whole neighbourhood of Robins in Devon was studied closely by David Lack for his celebrated book The Life of the Robin, and it was David who discovered that Robins commonly form into pairs soon after first light. Pairing up begins with the prospective female flying into the male’s territory, and after belting out a brief burst of song she will then fly right up to the male. The Robin’s red breast is of course its most conspicuous feature and is frequently used for display purposes, to both impress and intimidate. Initially confronted with an intruding Robin at such close quarters, the male will aggressively display at her, which involves extending himself to show her as much of his bright red breast as possible. With wings flicked half-open, his tail cocked and the feathers on his crown standing upright, he will then often turn slowly from side to side, displaying his breast in a peculiar mechanical motion, which looks distinctly at odds with what is normally a busy little bird. Also replying with song of his own, at some point the penny must drop for the male when he realises that the Robin constantly perching uncomfortably close to him, despite his threat display, happens not only to be female, but also (crucially) a single female. Quickly changing his tune, he then invites her to begin feeding alongside him on the ground.

  With most Robin pairs keen to rear at least two broods during the course of the spring and summer, for the single-brooded Blue Tits there is no such hurry. Despite nest-building still being over two months away, it’s thought that pair bonds may well have already formed during the winter months, while the tits were travelling around in their mixed flocks. As the pair waits for the longer and warmer days of spring to cement their bonds, the female will already have a clear idea where she’d like to rear her young, and so at this time may begin spending the long winter nights at the exact location she intends to be her future nest site.

  As January draws to a close, established pairs of Peregrines will use this time to strengthen their pair bonds close to the nest site. Having tolerated the presence of itinerant Peregrines throughout the winter, a change of behaviour will start seeing them adopt a zero tolerance approach to any intruders violating the pair’s airspace. Any Peregrine still unwilling to leave at this stage risks physical violence from the incumbent pair, and trespassing Peregrines have even been killed. Peregrine expert Ed Drewitt reported a dead male found below an active nest in an urban site in Derbyshire in 2013, which was thought to have been killed by the resident pair. Despite most Peregrines not forming clutches until at least mid-March, many pairs will have already begun copulating – behaviour that may well continue right the way through until the female is finally ready to lay.

  Still keeping to their respective territories, our resident Kingfishers will be keeping a low profile along their favoured watercourse in late January, where they’ll divide their time between fishing, roosting and preening. Having begun a complete moult of all their feathers after the rigours of the previous breeding season, most Kingfishers spotted tucked in tight against a river bank should by now be looking in pristine condition. Needing to find enough food just for one, they’ll nevertheless be surviving on minimal rations as so many freshwater fish will be tucked away and moving little during the winter months.

  With any cold weather continuing in the same vein, those British-breeding Lapwings that escaped the worst of the British winter by hopping over to the continent will probably stay away until closer to the breeding season. For those hardier Lapwings that have either stayed in Britain or are cold weather visitors from the continent, late January will still find them crowding together in large, mobile flocks as they take advantage of whatever feeding opportunities present themselves.

  During winter, the Lapwings seem to favour either large areas of mixed and arable farming or improved permanent pasture. Where arable land is more common in central and eastern England, Lapwings are often found in the highest concentrations on winter cereals, but they’re quick to move to pastures further west if temperatures continue to drop. It seems that pasture is better at insulating the ground, so the Lapwings may still be able to dig for earthworms when conditions are freezing elsewhere. Moving to coastal farmland is also an option for any Lapwings really struggling at this time of year, as soil temperatures here tend to be marginally higher than further inland. This is because the sea cools down more slowly than the land in winter, and is the main reason why snow on the coast scarcely settles when compared to inland locations at a similar latitude and altitude.

  Historically Bewick’s Swans coming to Britain for the winter fed on aquatic and marshland plants in wetland habitats such as flooded pasture. But as large tracts of lowland Britain have been drained and turned over for cultivation to arable land, over the last 40 years many of the swans have switched to feed on root and cereal crops. Certainly in Britain, crops such as sugar beet, winter cereals and potatoes have now become prime feeding areas for large numbers of Bewick’s Swans, particularly in eastern England. With the Ouse and Nene Washes thought to hold as many as two-thirds of all overwintering Bewick’s Swans in Britain, numbers will still be very high by the end of January. Feeding in fields by day, their roost sites will constantly change during the season, according to the water levels on the Washes. By contrast, the diet of Bewick’s Swans that have traditionally settled in more westerly areas of Britain will mostly consist of food from the managed grassland, saltmarsh and flood pasture. For the regular swans at WWT Slimbridge, dusk will see them flying in to roost on the protected freshwater pools with bellies full of grass to digest.

  Even in those years when relatively few Waxwings have ventured across the North Sea, the end of January will still see a smattering of records, mainly along the east coast. In a big invasion year, such as the winter of 2012/13 for example, late January recorded Waxwing flocks as widely dispersed as west Cornwall, Anglesey in North Wales and even the Outer Hebrides off the west coast of Scotland. It seems Rowan, Hawthorn and Cotoneaster may well be favoured by the Waxwings early in the invasion, but they must also compete for these berries with the resident Blackbirds, Song and Mistle Thrushes and other winter visitors such as Fieldfares and Redwings. This means that as their favourite foods become stripped, the Waxwings have to turn to seemingly less favoured food sources, such as Whitebeam, rosehips, Guelder Rose, Crab Apples, domestic apples, Privet and Mistletoe.

  BirdTrack Records of Waxwings reported in Britain and Ireland in January 2013.

  With the location that British Cuckoos spend the winter being only recently revealed, information as to what they might actually be eating in the Western Congolian swamp forests or lowland forests of northern Angola is non-existent. In Britain, Cuckoos eat hairy caterpillars, beetles, flies and ants, as well as the females predating eggs and chicks from any nests that they parasitise, and there is no reason to suggest that their diet will deviate dramatically while in Africa. Certainly the forests of the Congo are incredibly biologically diverse, so there must be plenty of invertebrate food on offer for the Cuckoos.

  Similarly for Nightingales at this time of the year, there are still far more questions than answers. It’s likely that most British-breeding birds are still in the coastal zone between Guinea and Sierra Leone and frequenting savanna woodland, thorny scrub, river gallery forest, humid forest edges and any areas of low secondary growth. Being a ground and perching bird, very fond of keeping to cover and rarely flying out in the open any more than is necessary, it is a safe assumption that they will also be keeping a low profile in West Africa. Before leaving Britain, Nightingales will supplement their insectivorous diet with berries, but it’s more likely that on their wintering grounds they will be feeding on beetles, ants and flies caught on the ground and in the undergrowth.

  From the little information we have about Puffins feeding away from the colony, the fact that large flocks are virtually never seen out to sea in the winter months suggests that they largely shun company, and being so spread out means they will be feeding at very low densities. Those Puffins that haven’t finished their wing moult will still have
only a very limited ability to disperse any distance, and it’s a fair assumption that when not roosting on the sea, the birds will divide their time between diving for food and preening at the surface. During the breeding season the Lesser Sandeel tends to dominate the Puffins’ diet, but during winter, the fish bury themselves into the sand on the sea floor, instantly making themselves more difficult to catch. This in turn means that the Puffins will be forced to turn to a far more varied diet during winter, consisting of other marine fish, marine worms and even squid.

  Because of the far more open nature and visible way in which Swallows go about their feeding business, more is known about their winter diet in southern Africa than for any of our other three summer visitors. It seems that in winter, the Swallows’ main prey is flying ants and beetles, but they also take spiders, caddisflies and grasshoppers. They will also take non-flying prey like bugs and caterpillars, with swarming termites thought to be an important part of their diet following rains. While flies are a very important part of a chick’s diet in Britain, it seems this prey is less frequently caught in South Africa. Being far more mobile, flies are more difficult to catch, and as the Swallows will still be moulting their tail feathers and outermost primaries at this time, they won’t have quite the fine degree of manoeuvrability that they would normally expect, so opt instead for the ‘easy meat’ of slower-moving prey.

  February

  The weather in February could best be described as ‘a curate’s egg’, or ‘good in parts’. On a cloudless sunny day it can feel like spring is bursting forth, only for the following day to bring the harsh reality of winter crashing back down with snow, ice and a brutal northerly wind. With the weather effectively operating like meteorological roulette, the cold, wet and windy days will see our resident birds hunkering down and committing to little more than finding sufficient food to see them through the nights. Better days, however, will kick start the mating game.

  Tradition says that Valentine’s Day on 14 February is supposed to be the date when our resident birds pair up, and indeed this certainly seems to be the case for birds like the Kingfisher and Lapwing. But many of our resident species, such as Robins, Blue Tits, Peregrines and Tawny Owls, will have already found their partner well before this romantic date and are by now looking to take their relationships on to the next level. Irrespective of their state of readiness, any of our year-round residents will still be further along the breeding process compared to our summer and winter visitors, which will only just be ambling up to the starting blocks in the great race to mate.

  Early February

  Having secured their territory for the oncoming breeding season, an established pair of Peregrines will use the first fine days of February to strengthen their pair bonds. For Peregrine watchers this represents the start of an exciting few weeks as the pair undertake spectacular courtship manoeuvres on the wing. Co-operative hunting between the male and female can figure highly in these early courting activities. Joining forces to hunt the same bird, the pair will often coordinate their attacks to counter any evasion attempts by their target. By swooping at a flock, in what may amount to nothing more than a dummy run, the male’s job will be to try and part an individual from the fold, which then acts as a cue for the larger and more powerful female to stoop at the bird using the element of surprise. Any prey caught successfully in this way will then usually be eaten by the female to ensure her body is in as good a condition as possible for the physical rigours of egg laying ahead.

  With the mixed feeding flocks slowly beginning to disintegrate, the first signs of territorial activity amongst Blue Tits will now become apparent on fine days. The winter can prove a savage time for Blue Tits, with only 50% of adults making it through to breed from one year to the next. For the juveniles, of course, it has been an even steeper learning curve since they fledged the previous summer, with a whopping 90% succumbing along the way to starvation, disease or predation. This would suggest that the average pair of Blue Tits may well consist of one experienced bird and another attempting to breed for the first time.

  Fine days in early February represent the first time that the male Blue Tits will endeavour to lay down a territorial marker by cranking up their singing from a series of prominent perches. Although not quite hitting the complexity or beauty of either the Robin or Nightingale’s overtures it is nevertheless a pleasing little song. Sounding like ‘see, see, see-chu chu chu’, with the latter section ending in a short trill, this song will be heard increasingly frequently as the month wears on.

  Those Robins heard singing ardently in early February will mostly consist of as yet unpaired males or birds still sorting out territorial issues. Males that have already managed to bag a female by this stage will now begin to sing in a much more subdued manner. Their first few days as a couple will be spent with the male following his new mate around as she explores their now jointly owned territory. It seems she has to learn the boundaries by trial and error, with any incursions into adjacent territories resulting in her being swiftly rebuffed by her new neighbours.

  By contrast, having held firm all winter, and possibly even for a number of years, any established pair of Tawny Owls will already be very familiar with the size and shape of their territory. From a range of studies carried out across Britain it seems a Tawny Owl pair’s territory can cover anywhere between 12 and 70 hectares, with dimensions depending largely on the quality of the habitat, food availability and density of other Tawnies in the area. The choice of a precise nesting spot within the territory may be a formality if one particular site has been used successfully the previous year. Alternatively, they may attempt to ring the changes following a previous nesting failure. Preparations in the nesting chamber are none too elaborate and amount to little more than the female excavating a shallow scrape that will ultimately hold her clutch, in little more than a month.

  Finally shaking themselves out of their winter torpor, early February will see our Kingfishers turning their attentions for the first time to the busy summer ahead. The minority of Kingfishers which held summer territories in more northerly or upland sites, but spent the winter in more benign lowland or coastal locations, may well now be beginning to return to their breeding grounds. Certainly the majority of males will have been holed up on their breeding territories all winter and so have no need to move, but many females will now have to up sticks in order to track down a mate. Kingfishers are mostly monogamous, but won’t necessarily pair with the same partner from year to year. It does seem, however, that in those cases when a pair does reunite, it tends to be in those locations where their previous joint summer territory had been cleaved into two winter territories.

  While still not quite ready to return to their breeding locations, as the time for departure rapidly approaches, Lapwing flocks will suddenly become far more restless. Bickering between birds can often be seen around this time and sudden erratic flights by birds around the flock can introduce a certain collective skittishness. When birds chase each other on the ground, they will do so with their wings raised to show their striking white wing-linings and use their broad black breast-band to both impress and intimidate. These actions are all dress rehearsals for the territorial and courtship behaviour that will soon be used in earnest on their breeding grounds.

  Before departure, from early February onwards, the Lapwings will also undergo a partial moult. Having already completed a full moult between late May and September of the previous year, to insulate them from the worst of the winter, this pre-breeding replacement of feathers on the head, neck and upper breast has an entirely different function – to look good. The change is most marked in the males, as they now develop their characteristic long, wispy crests, boldly marked black and white faces and striking black breast-bands.

  With summer arriving in Arctic Russia and northern Scandinavia much later than at the temperate latitudes of Britain, our two winter visitors are in no immediate hurry to leave our shores for their still frozen breeding grounds. Numbers of Bewic
k’s Swans are still high in early February, and as winter draws to a close, those populations that have spent most of the winter feeding on arable crops may well be forced over to pastures as their first choice becomes far more depleted. Also faced with the local exhaustion of food supplies, Waxwings at this stage of the winter will have to range far and wide to get their berry fix.

  Where they do manage to locate plentiful supplies of food, the Waxwing’s technique often seems to involve little more than eating large volumes of fruit in one sitting. The record for ‘prodigious Waxwing eating’ must go to a bird seen in Pembrokeshire during the winter of 1949/50. When watched for most of the day observers estimated one individual bird to have eaten between 600 and 1,000 fruits of Cotoneaster horizontalis. Unlike many perching birds, Waxwings don’t possess a crop in which to store these huge meals, but do have a section of the oesophagus that extends under the skin of the hind neck, which during intense feeding bursts fills in a similar way to a hamster’s pouches. Suffice to say that the 90g of fruit estimated to have been eaten by this bird still amounted to twice its own body weight!

  Faced with the cold conditions in the North Sea and North Atlantic it’s a fair assumption that our British-breeding Puffins will currently be preoccupied with finding enough food to eat throughout the daylight hours, particularly with an energetically expensive moult to be completed. From time-depth recorders placed on Puffins by researchers on the Isle of May during the breeding season, it was found that birds feeding chicks averaged over 1,000 dives per day, spending close to eight hours under water! Despite not having to fly to and from the breeding colonies, as the sea temperatures will be lower and food more difficult to find at this time of year it’s a fair assumption that certainly during the short days, the overwintering Puffins will have little time for loafing at the surface.