THE PIED FLYCATCHER
In the western oakwoods of Wales, the pied flycatcher is a familiar breeding species, and often it is the commonest bird there during the summer. But it is slowly expanding its range, especially with the help of extensive nestboxing schemes.
Over most of Britain, pied flycatchers are not nearly as common as their near relatives, the spotted flycatchers. Only in the western oakwoods of Wales are they a really common breeding species. They are small birds, about the size of great tits; the breeding males, in full plumage, are absolutely unmistakable with their striking black and white markings.
During their summer visits to Britain, pied flycatchers prefer woodland with a good tree cover at the canopy level, but without much of a shrub layer. Such open woodland is typical of the grazed sessile oakwoods of the southwest, much of Wales and some other parts of upland Britain. The males arrive on the breeding grounds in mid-April, often while the weather is still cold, and immediately start to defend territories and advertise nest sites. These are always holes-generally in trees-and the pied flycatchers sometimes try to displace resident tits. Although they are often able to defeat blue tits, great tits are generally more than a match for them. The females start to arrive four or five days after the first males. And pairs are quickly formed.
The birds build their nests of the soft outer bark stripped from honeysuckle stems, and can complete them in less than 48 hours. The female does most of the incubation, which takes about 12 days starting with the penultimate egg. The young remain in the nest for 14-16 days and fledge as spotty young birds looking like young robins or spotted flycatchers. Although they seem to stay within a few miles of the breeding site for several weeks, while the adults complete their total moult. Both young and old birds are almost impossible to see, and probably spend their time high in the tree canopy.
For most of the time, pied flycatchers feed on flying insects, which they take on the wing. They use convenient perches in the woodland, from which they make athletic, darting forays to catch moths and flies, returning quickly to the perch to watch for more prey. The early arrivals may find the weather so cold that hardly any insects are flying and have to feed on the ground, catching such creatures as spiders and ground-dwelling insects such as beetles, bugs and many larvae.
The young, in the nest, are fed almost exclusively on insect larvae. These may be moth caterpillars feeding on the oaks, or they may be sawfly larvae. In many years there seems to be a super-abundance of these creatures, so that the oak trees may even be partly defoliated: in such circumstances, the youngsters invariably fledge successfully. In other years, when there are few caterpillars or larvae, or if there has been heavy rain washing them off the trees, fledging success may not be very great.
It is easy to study breeding pied flycatchers in great detail, for they very readily breed in conventional nest boxes, and many studies have been undertaken in Britain and abroad. In addition, they can safely be handled by ringers and marked to make the different individuals recognisable. Recaptures of adult birds in later years have shown that the males are very faithful to their breeding areas, and may come back to nest in exactly the same nest box or one very close by. Many females do the same, but they are much more likely to nest in a completely different place: in a few well-documented cases more than a hundred miles distant from the previous year’s nest. Recaptures of birds ringed as nestlings show that the young often disperse very great distances: one Yorkshire-reared youngster was found in a Dutch nest box in a later year!
Ringing has also made it possible to chart the birds’ migration routes in some detail. Birds from Britain, Scandinavia and even Russia are found in the autumn in northern Iberia, mostly in northern Portugal. Obviously this is the important stop-over point on the migration southwards. Here they set up defended feeding territories for a few weeks as they put on weight for their further flight south to tropical West Africa.
Many eastern European pied flycatchers fly westwards at the start of their autumn migration, and some of these wander off course into Britain. Light south-easterly winds over the North Sea can cause large numbers of them, with other small migrants such as redstarts, garden warblers and whinchats to occur in eastern Britain, together with such exciting birds as wrynecks, barred warblers and Icterine warblers. Almost always these erratic arrivals are associated with cloudy weather which obscures the stars, for these provide the most important navigational information for the migrants. It has been proved that there are hardly any adult birds among the autumn arrivals, so that it is young and inexperienced birds that are involved. Ringing has shown that they are not doomed to die, for a number of them have been seen in later years in their normal range.
Even such a small bird as the pied flycatcher has, in the past, been hunted by man. In parts of Spain and Portugal, specially constructed spring traps were (and possibly still are) used to catch them for people to eat. Each bird weighs about 15g (4-oz) and they are fried, whole, after the feathers have been singed off them. International conventions on bird protection have had considerable effect over the last few decades, and this distressing practice is dying out. Now that Spain and Portugal have joined the European Community and the various EEC bird directives are being enforced in the two new member countries, these attractive little birds can undertake at least the European part of their long annual journey without fear of hunters. This gives rise to the prospect of further expansion of the range.