by Mike Dilger
Becoming ever more adept at feeding themselves, the young Peregrines will be continuing to venture further afield in late summer, safe in the knowledge that the ‘comfort blanket’ of their parents’ territory will still be there if necessary. While some may attempt to breed the following spring, the majority of juveniles are not thought to give it serious consideration until at least their second year and so will join a non-breeding population, whose numbers, distribution and movements are still little known. From studies of the movements of young Peregrines compiled by the BTO, the median distance travelled by over 500 ringed birds was just 45km, with only around a fifth travelling more than 100km from their birthplace. Despite ringing records suggesting that juveniles do not travel too far, this post-breeding dispersal could account for the old falconer’s terms of ‘passage hawk’ for any falcon in immature plumage observed in non-breeding areas. The movement of young British Peregrines over relatively short distances contrasts with other populations of Peregrines found, for example, in North America and across northern Europe and Russia, which are highly migratory, giving clarity to the derivation of the Peregrine’s scientific name Falco peregrinus, which translates as ‘wandering falcon’. These young birds will ultimately hope to fill the gaps caused by mortality in the surrounding breeding populations, and if lucky, skilled and tenacious enough, may even go on to establish new breeding sites themselves.
Also leaving behind all they’ve ever known as they attempt to either carve out their own territory, or at the very least stay out of trouble, the young Tawny Owls will finally leave their parents behind. Left alone to finish their moult in peace, it is doubtful that the parents will ever venture far from their established territory, as even when prey is thin on the ground, the pair would rather stick than twist. This incredible site fidelity may be one of the reasons why no ringed Tawny Owl has ever been recovered abroad or even foreign-ringed individuals found here, suggesting that the British population of Tawnies is a particularly isolated one. This may indicate that at some point the British Tawny Owl could even become a candidate for being a separate subspecies – with britannicus surely a suitable epithet!
Chased and harried by their parents, the local Kingfishers should once again briefly turn their waterfront into a blur of blue and orange as the second brood are chased out by their parents in a none too subtle fashion. The evicted juveniles, however, will have a few options – they can either find their own uninhabited stretch of river or lake, move to the coast where there is less competition or stay and fight for a stretch of river already occupied. Attractive territories, while being rich pickings, are often fiercely defended, and very few end up being wrestled away from older and more experienced birds, but it is not unprecedented. Wildlife cameraman Charlie Hamilton James, for example, observed a very strong-willed subadult female, which he thought came from the year’s first brood, that managed the feat of ousting the established resident pair holding territory adjacent to his house in the West Country. Once the young have dispersed, the river may suddenly and temporarily fall very quiet as the adults concentrate on completing their moult in peace, only too aware they will soon have to go back into battle to re-secure their own winter territories.
While fish in the rivers should still be plentiful for any homeless juvenile and moulting adult Kingfishers, this time of year can often present real difficulties for those species which feed principally on soil invertebrates. In a hot, dry summer the soil can quickly turn hard and baked, making soil conditions far more difficult for birds such as Lapwings to forage for prey. Additionally, with many arable fields covered by wheat, barley, oats, rye and rape in summer, the soil also becomes more difficult to access until the crop is harvested. Struggling to find enough food in farmland, feeding flocks during these summer droughts may instead be forced to feed in grassland or wetland habitats, with the result that normally peripheral habitats like reservoirs, gravel pits and sewage farms can often see an influx of hungry Lapwings at this time of year.
Despite the high temperatures in the middle of August, which would theoretically result in an abundance of invertebrate food, summer and autumn can paradoxically be a time of high mortality for inexperienced birds such as juvenile Blue Tits. Deprived of the safety net that their parents provide, many young will run a high risk of either being taken by predators, or dying from starvation or disease brought about by their poor condition. With a staggering 90% of young Blue Tits thought to perish before their first birthday, those managing to survive until November will have already found their odds of reaching the following breeding season to have improved considerably.
Falling silent for just a few short weeks, the Robin’s song can once again be heard from the middle of this month, as the younger birds attempt to nail down a winter territory. Distinctive for producing two different types of song, the Robin’s so-called ‘winter song’ which is generally heard from now until late December, tends to be far softer and more introverted than the male’s full-blooded ‘spring song’. This latter song is a more strident and confident expression of territorial ownership, and is designed to convey the joint message of both intimidating neighbouring males while attracting any nearby females. Despite the ‘winter song’ undoubtedly being more subtle, the message it conveys is no less important, as it will be the key to ensuring both a meal ticket and even a lifeline right the way through the depths of winter to the following spring.
Late August
Exactly why Waxwings spread across Britain and northern Europe in some years but not others is still little more than educated guesswork amongst many ornithologists. In most years the birds will usually winter close to their breeding grounds in the taiga forests or a touch further south, where temperate forests begin to take over as the dominant biome. However, following a number of good breeding seasons, the Waxwing’s population may increase quickly, causing pairs to nest further south than their normal range. The Rowan is believed to be a key species for the Waxwing to feed on during the cold, dark winter months, but it seems that the tree may alternate between good and poor fruiting years. So, when a sustained increase in the Waxwing population combines with a poor fruiting year, such as prior to the mass invasion of 2004/05, then a large number of birds will be forced further south than normal to find sufficient food.
The French ornithologists Jules Fouarge and Philippe Vandevondele carried out a study of the exceptional invasion of Waxwings across Europe during the 2004/05 winter and found that the first tell-tale signs of movement had already been noticed by the end of August. Indications of a ground swell in movement were first observed at sites like Luleå, on the shores of the Gulf of Bothnia in northern Sweden, and at Lake Ladoga, north of St Petersburg in the Russian Federation. The fact that these two watchpoints normally observe Waxwings is not exceptional, but reports of such high numbers passing through even before September seem to provide clear evidence that Britain should prepare for a deluge of these benign invaders.
The immigration of Bewick’s Swans into Britain is a far more consistent phenomenon when compared to the irregular arrival of Waxwings, but with cygnets still not yet ready to fledge, any adults with young will still be tied to the Arctic tundra for a few weeks yet. By the end of August the days of perpetual daylight in June will also have disappeared, and as the nights start closing in once more, the current darkness of around nine hours a night will quickly increase with each passing day right up to the winter solstice. As temperatues, and the hours available for foraging, begin falling quickly, it is imperative that the young fledge before the ice returns to the maritime waters of the Barents Sea.
Even for those Blue Tits summering up in the north of Scotland, the breeding season will have long since wound down, giving both adults and young plenty of time to complete their moult before the nights draw in substantially. Having started their slow annual moult possibly even before their young had left the nest, the adults, certainly in southern Britain, should by now be close to sporting a fresh new look. Having not themselve
s begun their partial moult until late July, it will be at least another six weeks before any southern youngsters begin to resemble their parents in the plumage stakes. Still trying to remain as inconspicuous as possible while they learn the life skills necessary, their dull plumage should not just help them avoid detection from predators keen to take advantage of their inexperience, but also ensure they don’t elicit aggressive responses from adults of their own kind. As the new body feathers slowly start to appear, this grubby intermediate phase will give the juveniles a decidedly dishevelled appearance as they’re glimpsed dashing to and from garden bird feeders or skulking in the shrubbery.
Having already acquired the all-important badge of adulthood that is the red breast, those juvenile Robins hatching from early broods should by the end of the month already be actively singing and chasing other youngsters in an attempt to secure a territory. They won’t have it all their own way for long though, because as soon as the adult Robins complete their own moult in September, the younger birds will suddenly be finding their mettle tested against battle-hardened veterans with previous campaign experience.
Like the Robins, Kingfishers will be desperately keen to procure and maintain a territory throughout the winter months. For those adults that have already chased their young away, giving them free reign once again over their domain, now will be the time to quietly concentrate on their moult, which should have started back in July. Taking over three months to slowly and painstakingly replace their feathers, while crucially remaining both able to fly and dive for dinner, those adults moulting later because of delayed broods may even be forced to suspend their moult for the duration of the winter. In these cases any old feathers that were retained throughout the winter are the first ones to be replaced during their annual moult the following year.
Due to the physically demanding nature of moulting, adult Tawny Owls will not want to be wasting any unnecessary energy re-establishing territories while actively growing and replacing their most important feathers, meaning that most woodlands should be ‘hoot-free’ zones until at least late September. While the moult of the body plumage might drag on as late as December, the feathers responsible for flight should by now have largely been exchanged for pristine versions, leading to the owls now turning their attention to the replacement of their tail feathers. Also in the middle of their own respective moult, those Lapwing flocks foraging amongst arable crops should begin to see easier feeding opportunities arise as crops begin to be harvested from the fields. The resultant ploughing of the stubble, in preparation for planting, should also, quite literally, unearth a multitude of invertebrates which these keen-eyed birds will be able to exploit as and when opportunities arise.
Having suspended feather replacement until their young were fully fledged, the juveniles’ increasing independence should finally allow the adult Peregrines the peace and time to quietly finish their moult by the autumn. In many cases it will also be in the adults’ interest to remain on their breeding territory all year round where possible, as any falcons ‘deserting’ a claim could find it occupied upon their return. Their attachment to sites will of course depend on the availability of food throughout the winter, and certainly for those pairs nesting in towns and cities, the presence of feral pigeons all year round may mean there is no need to leave at all.
With many urban sites also able to offer an abundance of roosting sites, it is not difficult to see why available Peregrine territories in some British towns and cities may be in short supply, if not already at saturation. The fact that fledging Peregrines may be finding it more difficult to find suitable territories was recently revealed by one of the first confirmed cases of co-operative breeding in Britain. As shown on the BBC wildlife programme Springwatch, a young male raised in 2011 from a well-known site in the city of Bath was then filmed helping to raise his parents’ 2012 brood. While a touch clumsy and haphazard due to his inexperience, he was nevertheless able to beg a share of the food from his parents while also enjoying their protective custody. Helping to rear his own kin might also mean that he could be in a prime position to inherit a top piece of Peregrine real estate should any tragedy befall his parents in the future.
As only a tiny minority of ringed Puffins have ever been recovered away from their traditional nesting sites, until recently very little was known about the travels of these mercurial seabirds after the breeding season. When not tied to their colonies Puffins are rarely seen from land, and so were assumed to disperse widely offshore. Additionally, as no large flocks ever seem to be spotted, it is believed they must also spread out at a low density, possibly in small, scattered groups. In recent years there has been a major advance in our knowledge of their movements through the use of geolocators. While having limitations as a technique, due to any birds with the logging devices attached needing to be re-caught and an inherent geolocation error of ±185km, the work of Mike Harris et al. studying the Puffins on the Isle of May has revealed they are indeed very mobile. The data-loggers recovered for this breeding site off Scotland’s east coast have revealed that after initially remaining in the north-west North Sea, and reasonably close to where they bred, a movement then takes place. The research work revealed that three-quarters of the birds successfully followed then moved around north Scotland, to spend most of the rest of the year well out into the Atlantic. By comparison, recoveries of ringed birds from populations in western Britain seem to suggest that they may disperse even more widely than those Puffins from the North Sea, with west coast birds moving through the Irish Sea and recorded anywhere from Greenland and Newfoundland to France and the Western Sahara. It has also been suggested that the movement of Puffins from eastern colonies to the Atlantic may be a relatively recent phenomenon, brought about by worsening conditions in their traditional North Sea wintering grounds. With sea temperatures rising in the North Sea, this may have lead to the Puffins’ food being driven further north, which in turn will have lead to the birds themselves being forced to follow.
For those Cuckoos, such as Chris, that entered Africa via Italy, the end of August should find the majority of these birds fattening up in and around the Eastern Sudanian savanna in southern Chad. The location of this sub-Saharan stopover appears to differ, however, from those Cuckoos that took the Spanish/Portuguese route into Africa. According to the satellite telemetry data these Iberian birds seem to prefer feeding and resting up at this stage of their journey in northern Nigeria, at least 1,000km further west of their Italian cousins. The feeding area for the more westerly Cuckoos seems to fall into the Western Sudanian savanna, a habitat that, while heavily fragmented due to the large human population in Nigeria, is considered broadly similar to the savanna habitat currently being used by the British-Italian Cuckoos.
Over 4,500km away, back in Britain, the adult Cuckoos’ progeny should still be gorging themselves on a variety of caterpillars and other invertebrates as they too prepare to depart. A few weeks after gaining independence from their weary host parents, there does appear to be an element of dispersal from where they hatched, as the young Cuckoos spread out in all directions. With a couple of records of British-reared juveniles observed as far away as Denmark and Germany during this period, this movement is believed to be different from the proper migration, which observations seem to confirm does not occur until early September.
If the movement of Nightingale OAD is representative of the migration of many British Nightingales currently on their way to Africa, then the end of the month should find them in transit towards the Iberian Peninsula. The data from the geolocator of Nightingale OAD certainly indicate that the slow progress of this bird seems to be because it will have been feeding en route, and with little of the haste that proved such a prominent feature of other tagged Nightingales followed to the breeding grounds in spring. Having taken a detour around Paris in the middle of the month, the fourth week of August saw OAD skirt past the western end of the Pyrenees, heading down to Madrid before then taking a right-hand turn towards its third Europe
an capital city in the space of just a couple of weeks – that of Lisbon in Portugal.
The believed migration route of Nightingale OAD between England and north Africa in the autumn of 2009.
In most years the fledging of their second brood will mark the end of the breeding season for many British Swallows. Finally freed from the constraints of chick-rearing means the adults may keep this second family together for a longer period than would have been the case for their first brood, with some kin possibly remaining together until at least the point when migration gets under way. Still not terribly competent flyers, initially the newly fledged young will need any help they can get as they come to terms with the very real dangers posed by domestic cats, Sparrowhawks and moving traffic. However, after a few days of flying lessons the young should have become sufficiently proficient to spread their wings further afield as they begin a process of familiarising themselves with both the general area and the local Swallow population. Gaining a knowledge of their immediate neighbourhood is not only believed to aid with successfully navigating their return the following spring, but also to help pinpoint any potential breeding sites or roosting spots in future seasons. Certainly for Scottish Swallows, however, these ‘fact-finding’ trips will not last long, as the deteriorating weather and shorter days combine to push the birds further south. Travelling initially short distances, as they migrate by day and roost by night, it won’t be long before the Scottish Swallows begin joining forces with their English and Welsh cousins as the entire summer population prepares for a mass autumn exodus.
