by Mike Dilger
By now in full laying mode, female Swallows will be aiming to produce an egg each morning until their clutch is complete. The number of eggs can vary between two and eight, but a clutch of four or five is by far the most common. As the eggs are formed directly from the female’s current intake of food rather than her fat reserves, the prevailing environmental conditions are thought to impact on clutch size. Each weighing in at around 2g, the eggs are usually white with varying amounts of reddish- or purplish-brown speckles and blotches. Only starting her incubation with the penultimate egg, as the female alone has a brood patch, on the few occasions where she disappears off to feed the male won’t normally sit on the eggs. Angela Turner reported that an incubating female will generally spend 60 to 80% of the day incubating her clutch, and as the male doesn’t feed her at the nest, she will need to intersperse these sitting duties with short feeding bouts lasting anywhere between two and nine minutes. Her incubation is of course carefully timed to coincide with the first large proliferation of insects in spring, meaning she shouldn’t need to be away from the eggs for any longer than is absolutely necessary. On particularly cold days, however, the female will need to spend more time hunkered down with the eggs, and when eventually forced off by hunger, she will just have to hope that the nest’s feather lining will help ensure the clutch doesn’t cool down too much before her return.
Having laid their single precious egg in early May, come the end of the month the Puffins will still have some way to go before their chick or ‘puffling’ will be finally ready to make its entrance into the underground world. Despite needing around six weeks for incubation, which is a remarkable length of time for such a small bird, the relatively constant temperature underground should give the pair enough time for short socialising breaks. When the pair are both present at the puffinry early or late in the day, they will rarely miss the opportunity to indulge in a spot of ritualised behaviour, such as ‘billing’, the ‘pelican walk’ or ‘spot-stomp’. Practised by generations of Puffins, these actions all reinforce the same message to any neighbouring birds looking on: ‘This is my mate for life, we have a strong bond and this is our burrow, so please keep your distance!’
June
The middle of the year brings a wonderful blend of the luxuriance of spring and the warmth of summer to the British Isles. As the sunshine warms the soil this is the time for huge floral diversity and is without doubt the best month to look for the most enigmatic and beautiful of all the plant groups – orchids. With flowers resembling monkeys, ladies and lizards, it’s not just the orchids that will be the centre of attention for insects, as most colourful blooms may well have a whole swarm of pollinators in attendance, keen to take advantage of the nectar and pollen on offer. With the summer solstice also happening this month, the long days will provide ample opportunities for the many birds now fledging to find sufficient food while learning the ropes away from the confines of the nest. For some youngsters, the extended parental care can last all summer, but for others it will be a steep learning curve as they are given the cold shoulder by mum and dad, keen to turn their attentions to brood number two.
Early June
After around 20 days cramped up in the nest, in quite possibly stifling conditions while competing for every caterpillar that arrives, many juvenile Blue Tits will decide they can stand the conditions no longer and begin to fledge. With most Scottish Blue Tits only just beginning to hatch at this point, it will definitely be the southerners leading the way, as the first chick jumps up to the nest entrance and grabs the rim of the hole with its feet before squeezing through into a world full of infinite possibility and danger. Fledging usually takes place early in the morning to give the birds all day to become accustomed to their new surroundings, and as the first bird leaves, this often gives impetus to the other chicks to seize the moment and cross the line from nestlings to fledglings.
Their parents will invariably be close by during this defining moment of the breeding season, and play their part with encouraging calls as the chicks are enticed out and hopefully up into the relative safety of the trees. With their distinctive bluish-green caps, yellow faces and still a hint of a yellow gape, juvenile Blue Tits immediately stand out even to the novice birdwatcher. Unsurprisingly, given the restricted room in the nest, their wings are still not fully grown, so upon fledging their flights are initially short, feeble and clumsy. Despite the best efforts of the parents to keep their young fed during this period, the harsh reality is that as many as 90% will not even see their first birthday, with the first few days out of the nest exacting the heaviest toll. Any young Tit grounded will immediately be at great risk from predators such as Weasels, Stoats and of course domestic cats. The youngsters will also have to remain alert above ground too, as Sparrowhawks will make short work of a defenceless Blue Tit with their own chicks hungrily waiting back at the nest. The other big factor affecting the survival of young and inexperienced birds like Blue Tit chicks will be the weather, and any prolonged cold and wet periods immediately after fledging can have a dramatic effect on the number of juveniles able to see the summer out.
Close to six weeks after hatching, and some 78 days since the first egg was laid, early June should see Peregrine chicks lifting off, as all their practice flapping enables them finally to defy gravity for the first time. Due to the elevated temperatures in towns and cities caused by the heat island effect, urban-nesting Peregrines may fledge a week or so earlier than their countryside cousins. As some of the chicks’ feathers are still in pin, they will often be a touch overweight on leaving the nest, meaning that their first flights can be clumsy and haphazard. Certainly any ecclesiastically-bred birds that don’t manage to flutter to a nearby spire or gargoyle on their maiden flight could easily become grounded in the graveyard below or even further afield. Often the smaller and lighter males tend to fledge marginally before the bulkier females, and those lucky enough to have grasped a suitable perch close to the nest will then be content to stay there for a few hours while noisily haranguing their parents into rewarding their efforts with something edible. Within the space of just a few days the young should have both strengthened their flight muscles sufficiently and lost enough weight to make flying much more straightforward, but it will be far longer before they will manage to master the dark arts of catching moving prey!
Also taking to the air for the first time, any surviving Lapwing chicks able to simply airlift themselves away from danger will have suddenly and massively boosted their chances of making it to adulthood. It has been calculated that Lapwings only need to rear between 0.8 and 1 chick each season to sustain their numbers, and the very fact that the British breeding population has fallen by over 50% in the last 25 years shows how a combination of agricultural intensification and increased predation levels are severely impacting the survival levels of this wonderful wader. Even after the young have begun flying they will remain dependent on their parents for at least another week, and can still be clearly picked out by their shorter crest, less well-marked face, scaly backs and incomplete breast-band. By the time their youngsters have begun to fledge, the adults will have already started their annual moult. But needing to remain airborne, in order to track down widely dispersed feeding opportunities throughout in the summer, it is likely the moulting process will not be completed until later in the autumn.
In the nest for a grand total of no more than 13 days, the Nightingale chicks will need to grow quickly on their non-stop diet of invertebrate food. As fledging approaches the feathered youngsters will suddenly become much more aware of their surroundings and crouch down if danger threatens. As a last line of defence they will have also developed the ability to gape in a threatening manner if any predator stumbles across the nest. The parents will be only too aware that the success of their entire breeding season will be riding on this one precious brood of chicks and so will give excited alarm calls and mob any potential predator zeroing in on the location of the nest. As a last resort the adults will also atte
mpt a distraction lure, where they will try to distract the predator by feigning injury, such as a broken wing, while fluttering around on the ground in a seemingly hopeless fashion. The predator – thinking an easy meal has presented itself – will be drawn towards the adult and away from the chicks, only then to see the adult Nightingale make a miraculous recovery at the last second.
Leaving the nest, the spotty and brown young Nightingales look superficially similar to fledgling Robins, and being still unable to fly for a further three or four days, will need to be quickly led away by their parents into the comparative safety of the surrounding undergrowth. Unlike the majority of their continental cousins, British Nightingales are only thought to have one brood, so with both the adults freed from any further breeding constraints they’re able to devote themselves to looking after their young for at least the next fortnight. Still reliant on their parents to find them food for at least the first week out of the nest, it’s thought that the brood may often be separated between parents, giving each youngster a better level of attention and more personal tuition in the ways of finding food. Dividing the chicks will also split the risk, thereby maximising the chance that at least some fledglings will make it through to autumn migration.
His duties suitably discharged when his first brood disperses into the surrounding countryside, the male Robin will waste little time in turning his attention back to his mate, who should by now already be sitting on clutch number two. As the male doesn’t generally feed the female while she incubates, this will give him a little time to catch his breath before the second brood begins demanding food. He will of course not abandon his responsibilities entirely during this down-time, and be on hand to safely whistle her off the eggs if and when she needs to feed. If his mate is tucked away on a nest with minimal visibility of her surroundings and a mammalian predator (such as a human) is observed too close, the male will often make a ‘tic-tic’ alarm to warn her, which once learnt is easily recognised. Birds such as Sparrowhawks are treated differently, as these represent not just a very real threat to the female herself, but also to the entire clutch if she were to be predated. If a Sparrowhawk is spotted close by then the male will make a ‘see-eep’ call, warning her to keep her head down and stay still. If all goes according to plan, and after only two weeks hunkered down on the nest and a mere seven weeks since her first brood hatched, the Robin’s second batch of chicks should then begin to emerge into the nest. Upon hatching they won’t immediately need feeding while they use up the last of their yolk reserves, but the removal of the broken eggshells from the nest will surely serve as a clear statement to the male that his relaxing break has just come to a shuddering halt.
Still with their first brood, the river can be a noisy place as the Kingfisher parents mercilessly force their young out of the family’s territory. Armed with little more than just a few days spent watching their parents catch fish with unerring accuracy and effortless skill, the evicted youngsters will have little choice other than to quickly spread out along the artery of waterways surrounding what was temporarily their home. With no knowledge as to where each watercourse leads, or which territories are already occupied, these can be incredibly testing times for the young naive birds. Usually within the first day of being chased away the young birds could be at least 300 metres away, and may have moved as far as a few kilometres from their parents’ territory in the space of just a few days. Those sites with plenty of fish and many potential nesting locations may see territories very close to one another, and so any youngster fishing on another pair’s patch will need to keep very quiet if it’s to avoid being spotted and subsequently driven out. However, if the young bird’s presence goes unchallenged, it may have landed in a vacant lot, and so proceed to staking an ownership claim. Any territories secured early by young Kingfishers will enhance their survival prospects no end, as catching sufficient food will only become more difficult as summer fades into autumn. The stark reality is that as few as 20% of all fledging Kingfishers will survive long enough to see their first birthday. But if they do survive this first tough year then the odds will start to improve, although not by much, as the BTO estimates that the typical lifespan of a Kingfisher is little more than a paltry two years. In fact the oldest Kingfisher recorded in Britain was four years, six months and 13 days when re-trapped, and while older birds undoubtedly exist, the Kingfisher is certainly in the ‘live fast, die young’ category.
Being such short-lived birds means it certainly pays to try and rear as many young each season as possible, which in the case of the Kingfishers can be achieved by attempting a second, and even very occasionally, a third brood. Those pairs successfully managing to fledge their first brood according to plan will be keen to nest again with all possible haste. Faced with this scenario, their first decision will then be whether to reuse the previous tunnel or attempt the time-costly, but more sanitary option of digging a fresh tunnel and chamber. If the pair decides the first tunnel is still fit for purpose, then the female will obviously need to wait until the first brood has fledged before giving the nest a spring clean. But if the adults do decide a fresh start might be better after the fledging of their first brood, then some time can be saved if the first brood’s diving lessons are delegated to her mate. Additionally, the second nest invariably seems to be excavated more quickly, possibly as the pair will by now have gained a good understanding of how to work with the particular soil type, which should enable them to dig more effectively.
Unlike Robins and Kingfishers, the long incubation period and extended adolescence of the Tawny Owl youngsters mean that their parents will never be able to rear more than a single brood each year. Despite a month having passed since the young first ventured out of the nest and into the trees, they will still be haranguing their parents to bring them food each night, behaviour that will in all likelihood continue right the way through the summer. With their breeding season now over, and in spite of the extra demands placed on them by their needy offspring, the adult Tawny Owls will by now have begun their annual moult. Keen to keep flying and yet not compromise their hunting ability throughout this energetically costly process, the shedding and replacement of particularly the flight feathers will be carried out in a slow and methodical fashion, possibly not being completed until early autumn.
Having commandeered the nest for itself, the Cuckoo chick’s next job will need to combine persuasion and trickery if it is to dupe the often much smaller hosts into the demanding business of keeping it sufficiently well fed. Naked and blind initially, the Cuckoo nestling develops a very rapid call, which is thought to fool the foster parents into believing their nest is full of hungry host chicks all calling at once. However, when they both arrive with food, there will only ever be one huge gape waiting to be filled. The hosts will of course bring in the same type of food they would normally feed their own chicks, so in the case of Reed Warbler hosts, for example, the diet will consist of either beakfuls of small flies or larger single items such as caterpillars, moths, butterflies, damselflies and hoverflies. As the Cuckoo chick has such catholic preferences, all offers will be gratefully received!
Eating the amount of food that would have kept an entire brood of either four Reed Warbler or five Meadow Pipit chicks more than happy, the single Cuckoo chick will grow quickly as both host parents run themselves ragged trying to keep up with the incessant demand. Although pink when hatching, by the time the youngster is three days old it will have turned black all over and developed a vivid orange-red gape to spur its foster parents on with their misguided mission. On the fourth and fifth days the feather quills begin to emerge, giving the youngster a dark and prickly appearance, and by the time its eyes open after around a week, the chick looks nothing whatsoever like the host chicks would have looked were their lives not cut so brutally short. By the time the feathers begin to emerge, the chick will have grown so quickly that the foster parents will be unable to brood their charge. In addition to being quite bulky, the chick will also be able to loo
k after itself and can adopt an amazing defence if threatened. Erecting its feathers and opening its bill to reveal a huge bright red gape, it will then suddenly stretch and snap its neck back in a surprising, intimidating and aggressive manner. Any potential threat promptly dealt with, the Cuckoo chick will then divert its attention straight back to the matter in hand – cajoling its foster parents to hurry up with more food!
As the Cuckoo chick continues to throw its weight around, many Swallows will be busily preparing for the moment their first broods start hatching. Emerging at around 18 days, all the chicks will hatch within a 24 to 36 hour period, and the first act of the female will be to make some more room for the youngsters by tossing the empty eggshells just a few metres away. At hatching, the Swallow chicks will generally weigh less than 2g and apart from a few wisps of grey down on the head, back and wings, emerge naked and blind. In common with many other chicks, for the first few days they’re unable to regulate their own temperature and so must be brooded by the female almost continually. During these early days the chicks’ food requirement will also be minimal, so the male should be more than able to cope as he brings in the first supplies.