Emperors of the Moor.

 I love the big Saturniid moths. Ever since I was a kid and I got to watch an Indian Moon Moth emerge from its cocoon at home, a story of which my parents love to remind me, I have loved the big Saturniids, their big, ornamented, often bright green caterpillars, their silk-spinning and their cocoons, a palace for their pupae, and the big furry faces of the adult moths, with their dark compound eyes, their soft and luxuriant looking fur, and their surprisingly appealing faces.  Huge, patterned wings of eye spots, translucent windows and elegant pastel colours. The Saturniid moths are heavy duty night butterflies of immense beauty.   Although a group of them are called ‘Giant Silk Moths’ they are not closely related to Bombyx mori the domestic species so brutally harvested to make ties and party dresses. They are big, widely distributed, heavy moths, and the family includes the largest moth in the world, the Giant Atlas Moth (Attacus atlas).

Here in Europe, and Britain especially, we have something of a paucity of Saturniid moths. While the beautiful Spanish Moon Moth (Graellsia isabellae), a species I dream of seeing in the wild, lives in Mediterranean Europe, and the Tau Emperor (Aglia tau) sits just across the channel as close as Northern France and Germany, we only have one breeding Saturniid in these islands, and it is far from the biggest of them. However, the Emperor Moth, Saturnia pavonia, is a stunning beast, no less.  Males are finely patterened with rich grey forewings with eye spots, and purple fringing, and just a hint of a snakes’ head pattern on the wingtips, recalling some of its giant relatives. Their hindwings are orange, with dark veins like window lead, and another set of eye spots.  The females are grey, but no less spectacular, slightly larger, broad in the abdomen, and retaining the dark venation, with purple notes like the heather over which they fly. The eye spots are presumably aposematic colouring to threaten potential predators, and do look owl-like. The highly active males patrol the heather and grassland on sunny days in April and May. First impression is of an orange moth, the colour of its hindwings, often part concealed at rest. Having done all their eating as larvae, adult emperors do not feed, representing just a short-lived dispersal stage to mate and produce eggs.  Males spend their lives frantically looking for an opportunity to breed before their stored supply of energy runs out.  Their broad, feathered antennae serve to detect the chemical signals given off by females. Antennae provide a way of distinguishing the sex of Saturniids, under less pressure to detect chemical signals over long distances, the females have relatively thin antennae.  These moths can be attracted using a pheromone lure, designed to imitate the chemical signals of a female Emperor Moth. It works on similar principles to lures used to control pest species like Codling Moth or House Moths, but we were not using it to harm the moths, merely as an opportunity to observe and marvel.  When we, myself and a few colleagues from Butterfly Conservation, hung up the pheromone lure, from a fence in a little birch-and-heather patchwork not far from Aviemore in the Cairngorm Mountains, the male Emperors were with us in minutes.  Confused, they searched for the female, perching up on pines, posts and people, fluffy winged bundles of sexual frustration. The source of their confusion was soon taken away and repackaged, the moths’ energy reserves are valuable, and, the onlookers satisfied with excellent views, the moths melted out over the heather moorland once again.

Emperor Moth, Aviemore, May 2023

Females are relatively sedentary, seldom wandering far from their host plant, retaining their energy to distribute their eggs, and to escape from predators should the need arise.  They need to save their resources. As such, their lifespan tends to exceed that of the males, sometimes spending 10 days on the wing. A proximity to the host plant and a sedentary lifestyle saves them the active hunt for somewhere to lay that is a part of the lives of longer-lived lepidoptera, and like most Saturniidae, they don’t seem interested in finding the correct host plant. Fortunately, the larvae have fairly broad tastes, munching on heathers, birch, bramble and several other plant species, contributing to their surprisingly wide range in the UK, from the Highlands to open country in Essex and Kent, and down to Cornwall.

Upon hatching, the larvae are black and hairy at first, growing quickly, until by high summer the caterpillars are well grown and magnificent. A large Emperor Moth larva is bright green, studded with dayglow yellow, or sometimes other colours, points like gemstones, each surrounded by hairs, or perhaps bristles. It spends its summer eating, before spinning a cocoon, undergoing its final moult, and becoming a pupa. It overwinters in this state, as like all lepidoptera its body is essentially turned to soup and rebuilt into its final form. In Spring the moth emerges again, through a unique one-way valve in its cocoon, in contrast to other Saturniids, which instead produce chemicals to melt a hole through their silken palace. Then they face the world and fly, the cycle beginning anew.

Emperor Moth Larva on Orkney

Keep an eye out from April-early June for the Emperor Moth. They can be seen across the country, I have encountered it on the coastal marshes of Essex, the West Country heaths, up here in the Cairngorm Mountains in Scotland, and even, as a fat green, yellow-studded, heather munching larva, next to the Ring of Brodgar on the Isle of Mull.  Sometimes the larvae are easier to find than the moth, and tend to be active at the times of year we’re taking our summer holiday, so take a look for them too. In heather habitats their bright green colouration and markings make them surprisingly easy to spot.  And be impressed, by our only native Saturniid moth. A truly magnificent beast.

A butterfly on Hawk Hardware.

 The long awaited gloom of a July evening on the West Country heaths as the extended summer day draws to a close. Though distant cars can still be heard they have faded into the ambience now, and I am alone on the earth. The damp, grey day of drizzle is giving way to still summer evening evening, though the sunset is still obscured by grey cloud. These conditions are not perfect, but they will suffice. I'd already been dazzled by the song of a Woodlark perched in one of the small birches which dot the heath, by scuttling Tiger Beetles among the eager blooms of Bell Heather, the Calluna yet to carpet the heath in purple. But there is one denizen of these South Western heaths that I am still waiting to see, waiting to hear. And now the light is fading and the distinct sound I am waiting for has not yet broken. I prepare to give up. Perhaps the weather is not good enough for this icon of warm scented summer nights. I dare to glance at my phone to check the England football result. It is good news. I sigh, irritated at how easily I am distracted. Where is my bird? I begin the walk back toward the car, noticing again the sound of traffic. 

It is as I stroll back that the sound creeps into my awareness. Distant at first, as if in my imagination. A growing, rising purr, perhaps if you had not heard it before you might think it an insect, a stridulating orthopteran of some description. It sounds a little like the tropical frogs you might have heard on nature documentaries, but far longer, uninterrupted, constant. It continues for minutes, rising and falling in volume, slowly but distinctly. The bird who is making it sits invisibly in a birch or one of the feral Scots Pines on the heath, slowly turning its head to project the sound around and about. Then, suddenly, quite unlike how it began, the sound stops. There is a quiet, single clap, and the bird is airborne before me against the sky. Its shape is almost raptor-like, long, pointed wings, a model of sleek grace, but its flight is nothing like a raptor, light, almost floaty, rapid changes of direction, recalling that of a Swallowtail butterfly over the Norfolk fens. A Nightjar! Anything but a Goatsucker, this long range migrant occupies a special place in the UK's avifauna. It is strictly nocturnal, and, by day, almost invisible, roosting stock still, a master of camouflage and concealment, either lengthways on a branch, or down on the ground among the heather. Folk myths give the bird its scientific name, Caprimulgus europaeus, the European Goatsucker. Pure slander, this insectivore has plainly never sucked a goat and never will. It flies like a butterfly with the body of a hawk, and any interest it has in livestock is strictly in the insects they attract and kick up when they move. Perhaps that is the bird's motivation when it approaches me closely, flying around me, and rising up in front of me to take a closer look, before, perhaps realising I have failed to live up to my purpose of attracting flies, he looses interest and flutters on into the rising darkness.

Nightjars are by no means confined to the West Country, though Aylesbeare Common in Devon, where I encountered them last summer, is a prime site for the species, as is lovely Arne in Dorset. They breed in Derbyshire, where their nest sites are kept somewhat quiet to prevent disturbance, and in Nottinghamshire, where they are a popular attraction at Budby Forest, part of Sherwood, as well as in Suffolk, the Brecks and on the Yorkshire Moors. They are, by the relative remoteness of their heathland habitat and their strictly nocturnal lifestyle, often overlooked and quite possibly under-recorded, though the loss of so much heathland over the passing decades has led to serious declines; and was once UK red listed, though it is now on the amber list, as sympathetic management has helped its fortunes. Go out for an evening stroll on open heath or moorland, or even in recently felled forestry habitats, and listen for the magical sound.

The European Nightjar is found in most of Europe and a swathe of central Eastern Asia during the breeding season, and it winters in sub-Saharan Africa. They are among the last Summer migrants to arrive in Spring, often not here until the second week in May. A stroll on the Early May bank holiday is too early, if you hope to catch sight or sound of one. They stay only a little later than the Swifts, and an evening stroll on the August bank holiday is likely to be a fortnight too late. By then they are on their way, flying by night through Europe, feeding and roosting in suitable habitat on the way. I encountered this bird in hand on my first day with the Hellenic Ornithological Society's ringing project on Antikythera in the Aegean. In hand they seem a different bird to the graceful creature on the wing, they have a huge gape, a massive pink maw with which they scoop up the moths and flies upon which they feed, and fringed with sensory whiskers. They have tiny legs, to closely grasp perches to better conceal their outline, and, while entirely without weapons, they hiss and gape, perhaps in imitation of a snake, when annoyed.

 Our Nightjar, Caprimulgus europeaeus, is one of a number of Nightjar species around the world, among the most spectacular is the Standard Winged Nightjar (Caprimulgus longipennis) in which the male trails long, modified feather  flag-tipped streamers behind his wings when he flies. He is resident in the savannahs of Sudan and Ethiopia. In Spain, the Red Necked Nightjar (C. ruficolis) can be found, looking remarkably similar to our, more Northerly species.  The scientific name Caprimulgus derives from the oft-repeated folk myth, that the Nightjar suckles from a goat, but the common name is appropriate, 'jar' being derived from 'churr' a description of the bird's haunting song.

Nightjar in hand in Antikythera, ringed, annoyed and shortly to be released to continue its journey. 

On my walk I enjoy the sound of the Nightjar multiple times, with several churring birds on several perches, and I almost miss a second close approach, within ten feet of my face, fumbling for my phone in the hope of capturing it on video for posterity, though I did record the bird cresting the heather, and its distinctive, buoyant flight.  I did get recordings of the sound and the floaty, butterfly-like flight over the gloomy heath, which I hope are available above if I understand Blogger's video uploading system. I had a truly extraordinary encounter, with a truly remarkable and very special bird. 

Dartford Warblers at Arne

Dartford Warblers

Dartford Warblers (Sylvia undata) are among the scarcest and most enigmatic passerines to grace these islands, and surely among the most charming. When vast tracts of heathland covered much of Southern England, the species was not uncommon, and it is named for Dartford Heath in North Kent, from which it has been absent for decades.  Perhaps more at home in Mediterranean Europe, it is on the edge of its range in Great Britain. With the increasing development and fragmentation of this habitat, sitting as it does in desirable Surrey and Dorset, it underwent decades of decline.  It is also said to be particularly vulnerable to predation by domestic cats, which can exclude it from small scraps of habitat saved from housing developments. An exclusive insectivore, and largely sedentary species, its greatest enemy is the British winter, persistent snow can wipe a colony out, and a cold winter in the early 1960s nearly did for the British population entirely, just a few pairs appearing after the snow finally melted.  However, amid great conservation effort and with possibly a small helping hand from climate change, the species is beginning to recover. 

Dartford Warbler at Arne.

There are a few places where these birds can reliably be found. Arne, and surrounding fragments of heath, and Chobham Common in Surrey, where I first met the species, host good numbers year round. They are vulnerable to disturbance, and responsible birders do not go tramping through the heather at any time of year. Occasionally individuals turn up on the coast in Southern England, undertaking short movements to avoid the very worst of the weather.

A view from Arne.

It was at the RSPB’s magnificent pristine heathland reserve at Arne, near Wareham in Dorset, that I had my most recent, and most magical encounter with these gorgeous little passerines. A solo expedition to one of my favourite corners of the country in the hope of catching up with Nightjar (I did, but not enough to blog about), I camped near this magnificent spot, a large tract of Dorset coastal heath on Poole Harbour overlooking Brownsea Island, managed impeccably for conservation, and took a long stroll among its heathland rides.  Arne was abuzz with dragonflies and butterflies and hoverflies, and 90 common spotted orchids grew along the bank of one small pond which must have hosted half a dozen different Odonata, including an iridescent Downy Emerald and a striking pair of Emperors including an Ovipositing female. It was becoming a good day.

Emperor Dragonfly (Anax imperator) ovipositing at Arne. 

 It was the song of the Dartford Warbler that first caught my attention. Imagine the song of a Whitethroat (Sylvia communis), and consider the qualities and notes which ensure the song is often described as “scratchy.”   Now distil those scratchy qualities, concentrate that Sylvia scratchiness,  andyou will begin to imagine the song of the male Dartford Warbler.  The male caught my eye first too, a small, dark coloured bird, with a longish tail, proportions somewhere between a Cetti’s Warbler and a Long Tailed Tit. He alighted briefly at the top of the heather, sang a few notes, and dropped back into the thick tangle of waist high vegetation.  He reappeared and my eyes strained to see his features in the sun glare, his dark blue-grey back and wings contrasting little with his dark pink-red underparts, and he had an air of cultivated scruffiness.  Rooting in the gorse he popped up briefly with a beak full of spiders, before dropping down to stuff his spiders into the expectant mouth of a scruffy fledgling, brown and distinctly smaller than the adult, which had emerged from the vegetation.   The fledglings and the female never left the thick heather and gorse, appearing to my eye only briefly before returning to the shelter of the thick heather canopy, but the male returned to his commanding lookout and sang, re-stating his claim to this his fragment of the coastal heath, the precious resource upon which his family depend.  Perhaps by remaining in this prominent position he also provided a distraction display focussing the attention of birders, and any would-be predators, on him, allowing the more vulnerable youngsters to slip away.

It was a magical moment with these scruffy, charismatic little survivors, and conservation icons of the lowland heath.  It was heartening to know that, with many small birds finding their breeding cycles disrupted by the late snow this spring, at least some of this most cold-sensitive warblers had successfully fledged broods. This family appeared to be doing well.