Woodland wonders
Spring is the perfect time of the year to go in search of songsters of the ‘Celtic rainforest’, as Steve Wiltshire explains…
If I had to choose just one place to go birding in Britain during spring, I’d head west in search of Atlantic Oak woodland. Similar types of woodland occur elsewhere in Europe – Norway, on the Iberian Peninsula, and Brittany in France, for example – but the majority of this special habitat is found in Ireland and along the western seaboard of Great Britain, from Scotland to Cornwall.
Because of this westerly bias some refer to it as the ‘Celtic Rainforest’ – and rain it does! Indeed, the very high precipitation levels, along with the warming maritime influence of the Gulf Stream, are exactly the conditions this woodland requires to thrive.
In Wales, there are 48,000 hectares (118,610 acres) of Atlantic Oak woodland, more than Scotland and England combined; and it’s where I’ll return this spring to soak up the atmosphere of these amazing places.
Atlantic oak woodland contains a mixture of Birch, Rowan, Alder, and Ash; but the majority (as the name suggests) is oak, and in particular, Sessile Oak. The trunks of these weather-blasted, gnarled, old trees are invariably covered in an array of lichens and mosses. Higher up, growing upon the bows and branches, are ferns and other epiphytes, present in such profusion and diversity, because of the moist conditions and the purity of the Atlantic influenced air.
There is very little shrub layer or ground cover present in these woodlands, having been grazed away by the ubiquitous Welsh mountain sheep. This woodland’s botanical diversity and structure is instead found clinging to and hanging from the branches in great mossy hanks. Whatever the time of year, the whole ambience of these woodlands is straight from Lord of the Rings, but it’s spring when they’re most magical.
Spring comes tentatively to the upland woods of Wales. But by early April, the trees will have begun to come into leaf, the oak’s male flowers dangling from the branches like tiny moss-green jellyfish. This definite shift in the season heralds the arrival of the avian embodiments of these woodlands: Pied Flycatcher, Redstart, and Wood Warbler.
This quintessential Atlantic oak woodland trio will have wintered in West Africa, perhaps Nigeria or Cameroon; but all return early in spring having timed their arrivals to coincide with leaf-burst and the bonanza of insects that will shortly follow.
The first Pied Flycatchers and Redstarts of the year will normally have returned to their Welsh breeding grounds by the end of the first week of April, with the Wood Warblers not far behind. Birds will continue to arrive right into May, but early in the season is the optimum time to see these summer visitors. They’re all in immaculate breeding plumage, leaf-cover remains sparse, and they’ll be singing, making them easier to locate.
Wood Warblers are probably the hardest of the trio to get a decent look at, often preferring to sing from high up in the canopy. Also, unlike Restarts and Pied Flycatchers, they shun nestboxes, so can’t be observed at a nestbox stakeout. But when seen well they are fabulous birds. The colour of sunlight through fresh oak leaves, and their shimmering song peeling through the trees, is the essence of a Welsh woodland in springtime. I recently heard a migrant Wood Warbler in an arid, rocky gully in southern Europe, and it seemed incongruous!
I closed my eyes and was instantly transported back to a cool, green, damp Welsh forest with babbling streams and mossy boulders. In Britain, Wood Warblers are scarce on passage; therefore, a trip to a western Oak wood just as newly arrived birds are singing to establish territories is the easiest way to see what, for my money, is our finest looking warbler.
Flash of red
Pied Flycatchers carry less of a sense of place with them, and encountering them as autumn migrants in Norfolk, for example, seems entirely appropriate. During that season, however, they are apparently washed-out, faded, unobtrusive versions of themselves.
But, when they first arrive in spring, the flycatchers, in particular, have a bravado that’s entirely absent for the rest of the year. Male flycatchers appear about a week before the females and, after a short period of intensive feeding, begin singing a simple two or three note refrain from their chosen nesting tree to establish a territory.
Now, they are hyperactive and bold, perching out in the open, and constantly moving to various heights throughout the tree to sing and watch for other flycatchers. Interlopers, in the form of other male flycatchers, are quickly chased off, and females, when they appear, will be displayed to. But it’s a brief window and all too soon, as the breeding season advances, they become more elusive, slipping quickly in and out of nesting holes with beakfuls of food, before eventually taking to the canopy entirely, becoming almost invisible.
In reality, Redstarts are less ecologically dependant on Atlantic oak woodland than Pied Flycatchers – I have seen them nesting in lowland woodland in Norfolk and orchards in the Midlands – but, nevertheless, they are inextricably linked to this habitat.
Their song, distinctive, but rather thin and unremarkable, remains extremely evocative of Welsh Oak woodland in springtime. And, whereas they have to be specifically sought out in other parts of the country, a flash of red across a woodland footpath or even a rural road remains a fairly common sight in Wales.
I can think of few other birds that can be identified so conclusively from even the most fleeting of views. Seen well – perhaps perched on a stone wall or fencepost, tail quivering like a gently twanged ruler – Redstarts are, arguably, Britain’s finest looking summer migrant.
I find this type of woodland aesthetically very pleasing, but what’s in it for the birds? And why are there no Wood Warblers nesting in the woods of Suffolk or Oxfordshire, for example? It’s thought that in these upland oak woodlands, the resident bird population is rather small, therefore, there is less predation pressure on invertebrates than in lowland woodland.
This means there is more food for migrants, especially in early spring when they first arrive back. Not only is there an abundance of early food, it’s the structure of the woodland that is more suited to these summer migrants.
In the Pied Flycatchers’ case, the old, rotting trees of this damp woodland provide an abundance of nesting holes, while the Sessile Oak’s gnarly, and crucially, fairly bare branches provide perfect perches. This is important for two reasons: flycatchers want perches from which to both see aerial prey, as well as to be seen by other flycatchers, an obvious sign that an individual holds a particular territory. The open woodland structure
and sheep-grazed floor also helps with the ‘see and be seen’ strategy, and flycatchers will often make sallies to the ground for insect prey.
Differing tactics
All three species choose this type of woodland to nest in for the same reasons: there’s plenty of food throughout the season, there are numerous nest sites, and the structure of the woodland suits their requirements.
But, of course, warbler, flycatcher, and chat each have their own subtly different tactics in order to successfully exploit their requirements from this habitat – what ecologists would call niche partitioning.
Wood Warblers aren’t in competition for nest sites with the other two, choosing
instead to nest on the woodland floor often under Bluebell leaves or tucked into a mossy bank. But Redstart and Pied Flycatcher are both hole-nesting species.
The Redstart, however, is more flexible in its nest site selection, and will utilise larger and less regular nest holes. I have seen them nesting in crevices where bark has pulled away from the main tree trunk, in the cracks of abandoned buildings, and in drystone walls.
The provision of nest boxes can reduce competition further still. That’s the nest site sorted, but all three species certainly forage for the same prey items ( beetle and butterfly larvae, spiders, and aerial insects) including the ‘flycatcher’ which, like the others, seeks out caterpillars to feed its young.
However, while the Wood Warbler spends most of its time foraging in the canopy, the Redstart and Pied Flycatcher both use all of the woodland from floor to canopy. But, again, there are subtle differences: the Redstart sallies for aerial insects less than the flycatcher, and forages on the ground more than the flycatcher.
Changing fortunes
The Atlantic oak woodlands of Wales are home to 40% of Britain’s Wood Warblers, half of Britain’s Redstarts, and almost 70% of the Pied Flycatchers. Young of all three species will hatch during the summer, migrate to Africa, and return the following spring to breed themselves. And that might be it, all of them having a lifespan of just a few fleeting years.
The brevity of their lives illustrates the tentative toe-hold these species have, and their fortunes can change very rapidly as they have done in recent years. In just over a decade, Pied Flycatchers have lost their Green status as “birds of least conservation concern”, moved quickly through Amber, and in 2015 were placed on the Red List as “birds of the highest conservation priority”.
Wood Warbler is also Red- (2009), and Redstart Amber-rated. The decrease for all of them has been rapid and dramatic. The quality of their breeding habitat has remained very similar over the period of decline during the last decade; and changing conditions in their wintering areas might be the root of the problem.
We could look to the Whitethroat’s devastating decline and equally dramatic recovery during the last century as an example of how Sub-Saharan migrants can bounce back.
But recently, studies have begun to point the finger at climate change as a factor for declines in migrant bird numbers, and a
complicated picture is becoming apparent, involving the timing of migrant birds’ arrival on their breeding grounds and the emergence of key prey items. Despite these worrying declines, Atlantic oak woodlands remain spectacular places in springtime. And on a sparkling morning in April, as Wood Warblers sing and Pied Flycatchers inspect nest holes, it would be hard to imagine everything wasn’t alright with the world. Lesser Spotted Woodpeckers can be found in many of these Welsh woodlands.
Spotted Flycatchers, too, are still present among woodland clearings, their declines appearing less dramatic in Wales than in parts of England. Blackcaps and Garden Warblers, although preferring a lusher understorey, sing from bushes at the woodland’s edge augmenting the soundscape with their fluty and fruity songs. Willow Warblers occur in wetter areas where Alder and Willow dominate, and any woodland streams in these parts are sure to have both Grey Wagtail and Dipper.
Overlooked habitat
The hills surrounding the woodlands are likely to be fairly barren upland ‘sheep country’ occupied by the odd Meadow Pipit. But it’s worth climbing up out of the trees, which are typically steep valley sides, to the interface between woodland and upland. This is a very interesting and somewhat overlooked habitat, known as ffridd (pronounced freeth) in Welsh.
It’s often just a thin band of land between the lowlands and uplands, consisting of a mixture of vegetation types, and has great importance for a whole range of wildlife.
Bracken may dominate but there are typically areas of Gorse, Heather, grassland, along with a few stunted Hawthorns and Rowans. This mosaic of vegetation types in close proximity is the key to its value for wildlife.
The ffridd is the best place to find Tree Pipit, Cuckoo, and that other contender for finest looking summer migrant, the Whinchat. On patches of open grass, there is even a slim chance of Ring Ouzel. Butterflies thrive among the ffridd, too, and at this time of the year, the rare Small Pearl-Bordered Fritillary may still be encountered.
In my opinion, Atlantic oak woodlands offer the best springtime birding experience: a wonderful assemblage of birds, producing a mighty dawn chorus, usually combined with great swathes of heady scented Bluebells. The epitome of the British springtime, concentrated into one wonderful woodland landscape.