Nightingales in November

by Mike Dilger

  Certainly for urban Peregrines, midwinter will also be a time for hunkering down in their respective territories as they go about the business of surviving winter. As the days continue to shorten, the birds will stay close to the core of their territory and even visit the nest site itself as they familiarise themselves with any scrapes used in previous seasons. This subtle shift from neutral to first gear will be the very first move towards the breeding season as they prepare to reassert their territorial rights and strengthen the pair bonds with their partner early in the New Year. On a day-to-day basis, however, most of their time will be spent roosting to conserve energy in between bouts either raiding their caches or hunting anything from pigeons to Pied Wagtails and Woodcocks to Water Rails.

  Mid-December

  When compared to deciduous woodlands, which are positively dripping with caterpillars in spring, most gardens are generally considered far poorer quality habitat for Blue Tits during the breeding season. However, as food supplies in wooded areas undoubtedly dwindle with Christmas just around the corner, garden feeding stations will suddenly become a much more attractive proposition to the local bird population. Frequently seen in ones or twos, it’s easy to underestimate the number of Blue Tits visiting a popular feeding station, both during the day and throughout the course of the winter. But just how many different Blue Tits may drop in during a single day was not fully appreciated until intense ringing efforts were carried out in a series of gardens. The sheer number of birds netted was able to show that well-visited gardens are capable of pulling in as many as 200 different Blue Tits in a single day, as a whole series of small flocks move through on a ‘regular beat’. In fact, garden birdwatching supremo Mike Toms from the BTO reckons that during the course of a winter, more than 1,000 different Blue Tits could visit a well-supplied bird table. This astonishing figure can easily be corroborated by BTO ringer Denise Wawman, who since 2008 has ringed 3,902 different individual Blue Tits in her small Minehead garden, with presumably many more individuals having avoided her mist nets altogether! Denise believes that many of the Blue Tits visiting her garden in winter hatched in local woodlands, with ringing recoveries showing that only a tiny percentage come from further than 5km away.

  Unlike the mobile Blue Tits, those Robins holding territory will be keener than ever to stay close to home as they continue to eke out a living in wintry Britain. Any Robin zealously attempting to protect a patch will still be unable to prevent other individuals from trespassing all of the time, particularly in those ‘hard to defend gardens’ with plenty of food on tap. In fact, Denise Wawman has managed to ring a grand total of 362 Robins within the confines of her small, but well supplied Somerset garden since 2008. This fact alone suggests that the individual Robin that many people often mistakenly consider to be ‘their own personal bird’ may instead be a whole series of imposters either residing locally or just passing through. In particularly harsh winters, when survival becomes the order of the day, territoriality may simply break down at popular feeding sites, as the incumbent Robin realises that chasing away all other intruding birds is a waste of energy and a pointless exercise. Without any nesting Robins from year to year, Denise thinks of her garden as a ‘neutral zone’, where the Robins seeming to form a ‘queuing system’ for the bird table in very cold weather. She says ‘they enter the garden from the north side, and fly across to the Lilac tree near the bird table, before moving through it towards the food. After briefly alighting on the bird table to grab a suet pellet, they then leave by flying around the house to the south. These departing Robins will then work their way back around the outside of the garden to rejoin the queue on the north side.’ Denise also adds that during the cold spells no fights were seen and there was only the occasional ruffling of feathers when a Robin went in the wrong direction or tried to queue jump!

  Irrespective of the weather, those female Robins that moved elsewhere in Britain to maintain a different territory way back in the autumn, will from mid-December onwards be considering a move back to where they will intend to breed. Any females returning to a familiar area, upon choosing a mate will then quickly be pressed into service, as the pair work cooperatively to maintain a joint breeding territory right through to spring and beyond.

  As the cold weather begins to bite, those territory-holding Peregrines which cached items earlier in the year when food was more abundant may well be forced into resorting to ‘something they prepared earlier’ to supplement their diet during times of hardship. With temperatures falling, the Peregrines can be assured that any Woodcock, Water Rail, Moorhen or Teal harvested during the autumn migration will suddenly see the shelf-life of their carcasses extended as the caching spots become turned into outdoor refrigerators. Sometimes these caches can run into tens of prey items and need to be stored with a degree of care to prevent them being discovered by other predators. Additionally, any items that become dislodged by wind or rain will not be retrieved if they tumble down to the ground below.

  Unable to create their own food store for the lean times, any Kingfisher opting to stay within its own territory for the duration of the winter will have little choice other than to find enough food or suffer the consequences. Faced with freezing conditions, it’s not unprecedented for Kingfishers to turn up at garden ponds hoping for an easy meal, and occasional observations have even recorded Kingfishers stealing food from Dippers and Water Shrews. In October 2007, one opportunistic or desperate Kingfisher in Essex was seen with a Pygmy Shrew in its bill, before the unfortunate mammal was presumably eaten. Such a highly unusual meal must be considered very much the exception to the rule for a bird that most consider to be almost entirely piscivorous, and usually when confronted with such untenable conditions on their own doorstep, many will simply move elsewhere.

  After initially having turned up the volume in late October, presumably to prevent young Tawny Owls from attempting to settle within established territories, there will be a renewed urgency of calling by the adults as December proceeds. This ‘second wind’ will often continue right the way though into January and beyond as they gear up for the breeding season early in the New Year. For those pairs holding a rural territory, Wood Mice and Bank Voles are believed to form the most important component of their diet during winter, with a study between 1949 and 1952 in Wytham Woods, Oxfordshire revealing that these two species alone accounted for over 60% of all items caught during November and December. However, amongst those owls holding an urban dominion, birds appear to be the predominant prey items of choice all year, with a study in Holland Park, London revealing that birds formed 93% of the total live weight of all food caught by the owls. The main targets for these urban Tawnies seem to be House Sparrows, Feral Pigeons, thrushes, Starlings and Greenfinches. Despite the proportion of birds to mammals caught staying pretty constant throughout the year, the same study revealed that larger birds, such as Feral Pigeons and Jays, tended to be more commonly taken later in the year.

  The type of invertebrates taken by overwintering Lapwings during the course of the seasons will of course be largely dictated by both the annual cycles of their prey organisms and the prevailing feeding conditions. The Lapwings’ keen eyesight also means they need not just be restricted to feeding during daylight hours, as any nights brightened by moonlight will present excellent foraging opportunities, providing the ground isn’t frozen of course. When not actively feeding or moving between sites, much of the rest of the time will be taken up by roosting. Preferring larger, more tightly packed flocks for roosting than when feeding, the sites Lapwings will pick for rest and recuperation tend to be primarily chosen with safety in mind. Roosting either during the day or night, many Lapwings will prefer either to use ploughed fields or tussocky grassland, which offer the dual benefits of shelter from the worst of the elements and concealment from predators. Overwintering flocks will also use flooded fields as roosts, which will be able to offer protection from any terrestrial predators not too keen on taking a dip, such as Foxes.

 
A recent phenomenon has seen Lapwings roosting – particularly during autumn and winter – on the roofs of industrial buildings in northern towns and cities. This was first noticed in Greater Manchester in 1984 and then subsequently recorded in and around Bolton, Bury, Oldham, Stockport and Wigan. In 1993 this behaviour also began to be reported from across the Pennines in cities such as Leeds and Bradford. Often comprising groups of up to 600 birds, most of these roosting flocks seem to gather on the roofs mostly after sunrise, presumably after a night’s foraging, and then break up again just after sunset for feeding grounds at least 4km away. Remarkably, the roosting birds are surprisingly tolerant of all the activity that comes from residing in such close proximity to humans. Presumably once the birds have become accustomed to all the noise, then these industrial locations are in a position to offer some surprising advantages. From their lofty position these urban-roosting Lapwings will not just be out of reach of ground predators, but will also be afforded a level of protection from inclement weather – with the sloping roofs offering a variety of aspects for shelter and additionally the bonus of some free warmth transmitted through the roof from the building below. So, disturbance-free roosting right in the middle of our industrial heartlands might not be as daft as it sounds!

  As the food becomes stripped out of the Waxwings’ ‘arrivals lounges’ in the Scottish Highlands and Islands, which would have been thronging with Waxwings just a month ago, the distinct lack of berries by now will have initiated a mass desertion of birds. These flocks on the move will then effectively form a rolling wave trundling steadily in a south-westerly direction, so as the winter progresses, a Waxwing sighting will probably be more likely in Axminster than Aberdeen. However, with Rowan, Hawthorn, Pyracantha and Cotoneaster widespread either as native or cultivated plants right across urban, suburban and rural Britain, the only safe assumption when trying to catch up with a flock of Waxwings during an invasion year is that they could be found virtually anywhere.

  Typically far more restricted to a number of long-established overwintering sites across the British Isles, a hardy bird like the Bewick’s Swan will be positively revelling in the average temperature of around 4°C that typifies the month of December across Britain. Research work on the swans at WWT Slimbridge, Gloucestershire has shown that many of them are very site-faithful, and being relatively long-lived birds, many individuals are recorded returning to the same location year after year. By identifying the individual Bewick’s Swans from their unique bill markings the researchers at Slimbridge have been able to calculate that 87% of the adults survive from one winter to the next, and even for the younger, more inexperienced birds, the figure is around 66%. Of all the adults identified at the reserve each winter around two-thirds are paired, and with monogamy being the norm amongst these birds, the vast majority of pairings will only be broken by the death or disappearance of a partner. In fact ‘divorce’ is so rare amongst Bewick’s Swans that at Slimbridge mate-switching has only been recorded once while each partner was still alive. In this one exceptional case the birds ‘Piotr’ and ‘Patch’ were very much an item during the winters of 2001/02 and 2002/03, however in 2003/04 and 2004/05 ‘Patch’ was suddenly found to have paired with ‘Peploe’, leaving poor old ‘Piotr’ to return alone. So deep-rooted is this monogamy that if one of the swans loses its mate, the researchers have calculated it could then take the surviving bird around five years to recover from becoming widowed, before breeding successfully with a new partner.

  In stark contrast, the Cuckoo is highly polygynous on its breeding grounds, and so it is unlikely sexual congress will be at the forefront of their minds as they continue to see out the rest of the year in either the Congolese forests or northern Angola. In both December 2013 and December 2014, when Chris the Cuckoo headed to Angola, he initially arrived in the northern province of Uíge. This region was historically covered with forest, wooded grassland and swamps, but has since largely been converted into a rich pastoral terrain reserved primarily for farming. After initially pitching down, on both occasions Chris then quickly moved further south, to near the coastal (and capital) city of Luanda. The coastal habitat surrounding Luanda is more arid than further inland, with large areas clothed in thick scrub. Quite why Chris and a select few of the other Cuckoos would leave the sanctuary of the Congo for the drier and more broken habitat of northern Angola is anyone’s guess; however, in 2013 the rainfall in the Congo was considered higher than normal. This wetter than average winter in Africa’s greatest forest may simply have made feeding conditions more unfavourable for the Cuckoos, which in turn forced a few adventurous individuals to seek better foraging opportunities further south.

  It was not until the data from the geolocator attached to Nightingale OAD were analysed that researchers at the BTO finally had the first definitive evidence that British-breeding birds spent at least part of their winter in the coastal scrub of West Africa. Up to that point the only record of any British Nightingale recovered in Africa was that of a bird originally ringed near Shrewton in Wiltshire in June 1974, which was subsequently found freshly dead in Morocco in April of the following year. Since the pioneering work with OAD, two British-breeding birds have been netted by British ringer Jez Blackburn and his team at Kartong Bird Observatory in The Gambia in the middle of December in 2011 and 2012. Situated on the coast and just south of the capital Banjul, the ringing location is centred around the Kartong Wetlands, a diverse site which comprises reed and rush beds, sand dunes, mudflats, mangroves, rice fields, savanna scrub and a remnant of what would have been the original forest cover. Both Nightingales were caught in exactly the same patch of dense thorny scrub, with the 2011 bird originally ringed as a juvenile near Ipswich, Suffolk in June of the same year, while the other Nightingale had previously been caught at Foulness, Essex in July 2011, only then to find itself being extracted from a second mist net, some 17 months later and 4,568km away. This remarkable connection between the counties of Suffolk and Essex, and a seemingly small and inconsequential site on the coast of west Africa, is all the more poignant given the fact that this apparently crucial scrub habitat continues to be cut down for firewood by the locals – one more reason why, with just 6,700 singing males recorded in the last survey, the Nightingale is continuing its alarming decline as a breeding bird in Britain.

  Occupying around 760,000 breeding territories in Britain, the Swallow is still thankfully one of our commonest summer migrants. Those British Swallows which successfully negotiated the epic journey down to their South African wintering grounds should by now be finding the weather becoming ever more agreeable with each passing week. With conditions becoming steadily warmer and drier, resulting in an exponential increase of flying invertebrates, the Swallows will need to be wary to ensure they themselves don’t also become targeted. The large winter roosts must be the equivalent of large honey pots to the likes of Eurasian Hobbies, Peregrines and Lanner Falcons as they attempt to snatch a meal during the brief time-slots when the Swallows are either descending to the roost at dusk or leaving at dawn. Having reached the sanctuary of the roost, the Swallows will still not be able to fully switch off, as Marsh Mongooses are capable of snaffling the occasional unwary Swallow. Generally though, these low levels of predation should not even scratch the surface of the large populations safely managing to roost at many sites.

  Whether Puffins are subject to predation during the winter months is currently unknown, but it’s a fair assumption that a combination of poor weather and starvation will surely be the biggest factors preventing these tough little seabirds from seeing the winter through. At most British colonies the Puffins will first start to be seen in the offshore waters from early March onwards, but thanks to the deployment of geolocators attached to a number of Puffins breeding on the Isle of May, it now seems that the first moves in the direction of the breeding grounds are made much earlier. In pioneering work following 13 Puffins out at sea following their dispersal from breeding grounds on the Isle of May, researcher Mike Harris a
nd his team were amazed to discover that ten of these birds quickly left the North Sea for presumably better feeding areas in the Atlantic Ocean. However, by mid-December, all eight of the birds whose devices were still functioning, had returned to the North Sea. This suggests that their wing moult, which will have resulted in a four or five week period of flightlessness, must have finished by then, leaving just the moult into breeding plumage to be carried out. The reason for moving ever closer to the breeding colonies with a full three months yet to go can only be speculated upon, but being a species that is not only site-faithful, but also frequently burrow-faithful, might suggest that ‘the early Puffin will get the burrow’!

  Late December

  As the nation sits down to enjoy a Christmas dinner with all the trimmings, Robins up and down the land will also be using the season of goodwill as a time to change their tune. Being the only British species to sing persistently throughout the Christmas and New Year period, the Robin’s melancholic winter song, which commenced after their annual moult in midsummer, will suddenly become replaced by a much more strident version. This clear signal that spring has just come under starter’s orders, will see those males holding territories suddenly declaring their occupancy from much more prominent positions amongst the bare branches. Singing at potentially any time through the day, and even at night, when some urban Robins are tricked by streetlights into thinking dawn is imminent, their characteristic song is capable of considerable variation. A number of the notes even appear to be well above our audible range, making the song sound different and possibly even more impressive to those birds within earshot.