David Bradley – Page 2 – David Bradley Science Writer

Getting my Goat Moth

A rather rare animal turned up in the garden a few nights ago. A Goat Moth, Cossus cossus.

Now, you might look at this chonky insect, which looks like a chunk of broken-off twig, and think why on earth did the early entomologists call it a Goat Moth?

Well, as is often the case, moths are named for characteristics of their larvae (caterpillars) rather than the winged sex-machine adults. For example, the Elephant Hawk-moth is so-called because its larva is grey and wrinkly looking, with a couple of dark markings at one end that look like nostrils at the end of an elephant’s trunk. Looking like a miniature elephant’s trunk would seem to be no protection against predators, but when this caterpillar moves it bears more than a passing resemblance to a snake.

Meanwhile, the Goat Moth larva, which is shades of brown and orange looks more like a tiny scorched baguette rather than a goat. So, what’s the origin of the name? Well, it’s all about molecules. The larvae feed on the wood of deciduous trees and produce a delightful chemical cocktail containing various volatile acids, butyric, valeric, caproic, and caprylic acid.

You would probably recognise the vile smell of butyric acid immediately, it smells of vomit, valeric acid, on the other hand, has an unpleasant sweaty smell but is also an olfactory note in the stench of porcine ordure. Caproic acid and caprylic acid, as their names might suggest, alluding to caprine, meaning goaty, both have a rancid, goaty smell and are present in the urine of male goats.

If you’re a bird checking out the local larval buffet and there are some sweet-smelling caterpillars around alongside ones that smell of BO, puke, pig poo, and goat wee, which one are you choosing to take back to your chicks for their breakfast.

Given all that, sadly the Goat Moth is on the decline with only a few pockets around the UK where they might still be seen, including Cambridgeshire. For now. Loss of woodland habitat to developers and farming will inevitably see the decline of a moth that eats wood and takes 4 or 5 years to reach the pupation stage before metamorphosing into an adult.

Eying up the Eyed Hawk-moth

Instead of camouflaging themselves to hide from predators, lots of animals exploit a phenomenon known as paraedolia*. Pareidolia is the perception of seeing familiar shapes or patterns, such as faces or objects, in something without or a face or where the pattern or object does not really exist. Humans experience it a lot, it’s why we see animal shapes in the clouds or a gnarly face in the branches and bark of a tree. And why some people think there are Martians, because a mountainous feature on the Red Planet looks like head with eyes staring up at the planet’s rarified atmosphere.

Eyed Hawk-moth showing the oculi on its hindwings

One of the common features of pareidolia in animal defence is to display fake eyes in some way. I’ve mentioned the four false eyes, oculi**, on the wings of the Emperor moth a feature it shares with the European Peacock butterfly. But, other moths keep their eyes hidden from view until they need to make an impression.

The rather obviously named hawk-moth known as the Eyed Hawk-moth, is well camouflaged when it keeps its hindwings covered by its forewings. If startled or pecked at by a bird despite its leafy camouflage, it will flash its hindwings each of which has a rather realistic circular pattern of scales. This, along with the colouration adjacent to the oculi and their sudden display gives the impression of a face looking back at the predator. It’s presumably enough to scare off a hesitant bird.

Intriguingly, the moth puts on a good show of looking like a face staring back from the angle shown in the photo above, but I’ve flipped the shot below and in many ways this gives even more of an impression of an actual animal, I’d say.

Inverted view of the Eyed Hawk-moth looks even more like an animal staring back at you when the hindwings are revealed

There are countless examples of paraedolia in action among the moths and their larvae. Interestingly, this species as with several others, such as the famous Death’s Head Hawk-moth has another feature that uses the effects of paraedolia. While, the wings look like leaves, the back of the moth’s head also has markings that give the impression of a face perhaps belonging to a smaller animal that might nevertheless bite back if a bold bird tries to make a meal of the moth.

Meanwhile, is there such a thing as olfactory pareidolia? The larvae of the Goat Moth have a very strong, unpleasant smell as they exude various volatile compounds – butyric (vomit smell), valeric (pig poo smell), caproic and caprylic acids, the latter two are in male goat urine and smell very unpleasantly caprine. So, these smells presumably are recognised as offensive by predators, which are deterred from eating something so malodorous.

*Paraedolia – from the Greek para meaning alongside, beyond or else irregular, abnormal and the Greek eidolon meaning appearance or reflection.

**Oculus, plural oculi – from the Latin for eye.

What gets my goat?

You know what really gets my Goat Moth? A UV lamp in the garden on a balmy, but wet, late spring night.

This chunky creature, the UK’s heaviest moth, is a Goat Moth, Cossus cossus. It’s called the Goat because its enormous larvae smell characteristically caprine.

It’s a proper bucket-list moth for a lot of mothers because it is increasingly scarce and not commonly seen in England even in areas that might be referred to as its strongholds. Cambridgeshire is one of those. I potted it photographed it, and then shared it far and wide to envious acclaim. It has now been rewilded some way away from the garden and is unlikely to return.

Goat Moth overhead view, with the moth on a piece of bark that gives a clue as to how good its camouflage is

Its larvae are very big and burrow into deciduous trees to feed on wood. This species and its relatives are known collectively as carpenter moths because of their wood work. Digesting wood takes a long time, so the larvae (caterpillars) might live for five years before pupating. The decline of the species is sadly most likely due to property developers and farmers grubbing out woodland to make way for housing and crops.

Back of the moth's head, has a scary looking "face" #pareidolia — Back of the moth’s head, has a scary looking “face” #pareidolia

So, that thing about the larvae smelling like goats? Basically, they produce various chemicals that have strong odours as a deterrent, several of these chemicals are also exuded by male goats and present in their urine, for instance. – butyric acid (which is generally thought to smell rather unpleasantly of human vomit or body odour), valeric acid (also an unpleasant sweaty-smelling compound found in porcine ordure), caproic acid (given the name, a goaty, caprine, smell), and caprylic acid (also has a rancid, goaty smell).

Closeup of the scales on the Goat Moth, the beige scales resemble farfalle pasta, the little bows

Light pollution is morphing moths

Artificial light at night, a ubiquitous byproduct of urban life, is have a negative effect on the natural world. A study in the journal Biology Letters has looked at the impact on moths, and specifically the Spindle Ermine moth, Yponomeuta cagnagella. The research shows that light pollution is not only disrupting insect behaviour, but could be driving evolutionary change that is changing the wing shape and morphology of this moth, and perhaps others.

Ermine micro moth of the Yponomeuta genus of which Spindle Ermine is one

Spindle Ermine is a night-flying moth and like many others is drawn to sources of light, a phenomenon known as positive phototaxis. In modern urban environments, moths drawn to streetlights or lit buildings often fail to find mates, suffer from disorientation, or fall prey to predators. These factors reduce their ability to reproduce and survive.

Earlier research has shown that urban moths display weaker phototaxis than their rural counterparts. This divergence raised questions about whether the shift was environmental, perhaps due to repeated exposure, or whether it indicated a deeper, evolutionary adaptation to urban conditions.

The new research found wing morphology is different between moths of this species with strong phototaxis compared to a weak response. Moths from urban areas tend to have smaller wings compared to those from rural populations (laboratory-reared populations). This change is genetic and inheritable, not just a generational response to the local conditions. Given that wing size correlates with flight capacity, smaller wings typically suggests reduced mobility.

The study showed that moths with smaller wings were less likely to be attracted to artificial light sources, supporting a hypothesis known as the “reduced mobility hypothesis.” This theory suggests that urban environments, with their almost constant illumination, may exert selective pressure favouring individuals that are less prone to wander or fly extensively.

Nature’s playlist – RSPB Ouse Fen, Over

A couple of hours circular walk around the Over side of RSPB Ouse Fen in Cambridgeshire today; almost 6km, about 9000 steps (for what that’s worth), according to the fitness app on my phone.

First sighting was a Hare dashing away as I got out of the car. Then, there were countless Reed Warblers to be heard jazzily kvetching among the reeds along with the less chaotic calls of the Reed Buntings, which sound like Yellowhammers that have been given the wrong musical score. An occasional Bittern boom interrupted the dialogue and one of those swooped very close flying across the river at Brownshill Staunch just I’d reached that point on the walk. A Pied Wagtail hopped and wagged its way along the railings there as I was heading back. No butterflies sighted at this point.

Back on the main part of the reserve, at least a couple of dozen Hobbies were making a flap about hunting and eating insects on the wing, some high, some low-flying. A couple of Great White Egrets lazily took to the air and different points and times and both settled back down not a few dozen metres from where they started, they must have had a reason.

In the shrubby tree area along the edge of the new footpath/bridleway there was even more birdsong – numerous Garden Warblers, Common Whitethroat, Lesser Whitethroat, Blackcap, Robin, Sedge Warbler, Wren, Great Tit, Chiffchaff, and distant corvids and Coots, and every, invisible Cetti’s Warblers (I heard half a dozen, but only saw the one as it darted from tree to tree). What’s a warbler, anyway?

Sitting up on the bench on the mound overlooking the southern part of the reserve, I could hear a Cuckoo and caught sight of it perched in a short tree a couple of hundred metres away. Far too far for a decent photo with all the heat haze on a sunny day like today. A second was calling from further along the canal towards the car park. Not far off, a Grey Heron shed its grey load as I stood up to head back to the car park and a Small Tortoiseshell butterfly hove into view ahead of me, took quick for a snapshot. Once back at the car park, I dictated this article into my phone to save on typing and as I was doing that watched a Cattle Egret come up from the cows and calves I’d circled when I first got here. The bird itself circled and landed in almost exactly the same spot that a scavenging Marsh Harrier had come down, having hovered briefly above the spot.

Among the other songs and calls, the incessant groans of Wood Pigeon and a Green Woodpecker laughing, or yaffling, at me as it undulates out of sight and out of reach of the camera. A couple of Yellowhammer, dashed from the tree near the car to another a few feet away as I clicked the key and unlocked the car, and a Whitethroat made the same panicky dash.

The wind through the trees, the babbling of fish and diving birds in the water, the constant songs and calls of all the other aves, seems curious to pass a young fellow wearing all-enclosing, noise-cancelling headphones as he walked past me with a curt nod. What could possibly be on his playlist that’s more worthy than a dozen warblers and a yaffle?

My playlist for the morning had 38 birds…there were probably others I didn’t quite notice or note.

Bittern
Blackcap
Black-headed Gull
Blackbird
Buzzard
Carrion Crow
Cattle Egret
Cetti’s Warbler
Chiffchaff
Collared Dove
Coot
Cuckoo
Garden Warbler
Goldfinch
Great Crested Grebe
Great White Egret
Green Woodpecker
Greylag Goose
Grey Heron
Hobby
Kestrel
Lapwing
Lesser Whitethroat
Linnet
Little Egret
Mallard
Marsh Harrier
Magpie
Mute Swan
Pied Wagtail
Reed Bunting
Reed Warbler
Robin
Rook
Sedge Warbler
Whitethroat
Wren
Yellowhammer

Dartford warbler – Curruca undata

The Dartford Warbler doesn’t warble and has little to do with Dartford. It’s ostensibly a bird native to the warmer parts of Europe and North Africa, but there are pockets living and breeding in Southern England and East Anglia. They are, however, very vulnerable to cold winters and don’t tend to thrive or even survive proper winters like those of the early 1960s. The Suffolk coast at NT Dunwich and RSPB Minsmere is probably about as far north as you will see them in the UK, but that will inevitably change with global warming and given suitable heathland habitat these birds will likely extend their range further north, unless stymied by a particularly bleak winter.

Dartford Warbler perched high on a shrub

The term warbler is a generic term for this sort of bird, but there are dozens of different types of warbler and lots of genus and most of them don’t warble at all. The Dartford of its name comes from the place where the first record specimen was shot and stuffed for posterity (it’s what the early naturalists did, see also netting and pinning insects).

The Dartford Warbler, Curruca undata, is in the same genus as the Lesser Whitethroat (also a warbler) and they both sit in the bird family known as the Sylviidae, which includes the Blackcap, the Whitethroat, and the Garden Warbler, all of which we see in the UK.

We were on Westleton Heath, Suffolk, because the usual patch Dunwich Heath was inaccessible. We counted ten Dartfords on a short walk around the heath. Saw none later in the day at Dunwich.

Dartford Warbler on gorse bush with bill full of spider

Great Reed Warbler – Acrocephalus arundinaceus

We are lucky enough to have an unusual return visitor to RSPB Ouse Fen (Earith) – a male Great Reed Warbler, Acrocephalus arundinaceus. UPDATE: Not seen nor heard since 3rd June 2025.

Great Reed Warbler peeking out from the reeds

This largest of the European warblers has turned up after over-wintering in sub-Saharan Africa, we assume, and landed in basically the same reedbed as he spent his time last summer. The species breeds across mainland Europe. I think there are a couple of dozen that end up in the UK each summer, but they’re spread far and wide, with almost no chance of meeting despite the males’ loud insistent song. I’ve added my recording of the bird’s song to Xeno-Canto.

There were a lot of birders trying to get photos of the GRW and one image I saw had him side-by-side with the much, much smaller Sedge Warbler. He is big! Some of the birders were suggesting this species is the size of a Common Starling…well…it might seem like that, but the measurements don’t quite stack up.

The biggest recorded GRW is a little bit smaller than the smallest Starling at least by wingspan. There’s some overlap between species in terms of length from the tip of its bill to the tip of its tail, but look at the difference in what they weigh! Here are the numbers:

Great Reed Warbler – 16–21 cm long, 25-30 cm wingspan, weighs 22 to 38 g

Common Starling – 19–23 cm long, 31–44 cm wingspan, weighs 58 to 101 g.

PIE Day – a book review of Proto by Laura Spinney

I have always been fascinated by words, perhaps not as much as I am fascinated by music, but as a youngster I persuaded teachers to let me study Spanish in addition to the usual French at school and then to add in German as an extracurricular activity. Wot a geek!

I wish I’d had the opportunity to learn Latin and Greek and to get a better handle earlier on of the origins of our language…but…the true origins of the most-spoken languages around the world come from a slice of PIE – the true mother tongue – Proto-Indo European.

In Proto, the latest tome from fellow science writer Laura Spinney, she takes us on an international journey to trace the origins and understand the future of language as it emerged from the linguistic Big Bang of PIE. She recounts the life of PIE, you might say. It’s a gripping read and for word geeks like me an instant joy to pick up subtle connections that may not have been obvious. Barbarians, Barbaras, Babel, babble, and rhubarb…all connected…there are many more.

The history, the journey, the migrations, the movements, the evolution. It’s all here. It’s not often one can say a non-fiction book is a pageturner, but this one had me hanging on every slice of the PIE.

Swift times

It’s almost four years since Swift expert Dick Newell built some large-scale nestboxes for our parish amenities, namely Village Hall and Sports Pavilion. You will recall we had our local retained firefighters to hand to install them. The swifts have not yet taken to these nesting sites, although 2025 may well be the year they do. Lots of locals with boxes on their houses have seen swifts investigating over the last few days.

On the evening of the 29th April, I spotted the first two Swifts over our house. Always wonderful to know some have arrived safely from their winter homes in sub-Saharan Africa. This species needs our help though, too many natural nesting sites are being grubbed out for housing development and rarely a thought given to installing nest bricks in the houses at minimal inconvenience or cost. Without swift action, these beautiful migrant visitors to our shores may disappear from the summerscape altogether. Numbers have halved in the last thirty years!

Meanwhile, I was thinking about their arrival dates. These have usually been late April, we have good records going back to 1907 that corroborate this. Local birder Ian E shared his first sighting dates for the village for the last few years: 26/4/25, 27/4/24, 28/4/23, 30/4/22, 25/4/21. Their arrival times are remarkably consistent over this period and for several decades before. So, is climate change having no effect? However, the very first swift seen in Cambridgeshire this year was 16th April at RSPB Fen Drayton.

Well, of course in their wintering grounds temperatures may be a little higher on average than in previous years, but that shouldn’t really make much difference to when they set off to their summer, breeding grounds in the north. Presumably, they’re driven more by changes in the day length and their internal body-clock. Obviously, they don’t know anything in advance of arriving about how things might have changed in the temperate north.

They arrive at almost exactly the same time each year from Africa and if it’s a little warmer than they expect, then they presumably get a nice warm start to the breeding season. It has been almost 27 Celsius in our Cambridgeshire village today, which is ten degrees hotter than it was this time last year and the year before. It is climate change, although not generally the rising temperature trend, but perhaps one of the increasingly frequent anomalous weather burps.

Aerial lifestyle – Common Swifts spend up to 10 months a year in flight without landing. They eat, sleep, and even mate on the wing.

Flight speed – They can fly at over 100 kmh (about 60 mph) during level flight, making them among the fastest birds in level, flapping flight.

Flying sleep – Swifts can shut down one hemisphere of their brain at a time to get 40 winks…well 20 winks.

Migration – They breed in Europe and migrate to sub-Saharan Africa for the winter, covering tens of thousands of km annually.

Ground contact – Once they fledge, young swifts may not touch the ground again for 2–3 years until they nest for the first time.

Screech parties – During summer evenings, swifts gather in groups and fly at high speeds through city streets and over the countryside, emitting loud, piercing screams.

Lifespan – Despite their small size, swifts can live an unusually long life, over 20 years.

Sticky nests – They build nests in crevices using saliva as glue, often in old buildings, under tiles, or in cliffs, and of course in nest bricks and nest boxes.

Wing efficiency – Their long, crescent-shaped wings and short tails give them an efficient body design for gliding and manoeuvring.

Identity confusion – Though they resemble swallows and martins, with their forked tails and aerial antics, swifts are more closely related to the hummingbirds with whome they share a common ancestor. Features they share with the swallows and martins (the hirundines) is an example of convergent evolution.

Welcome to Planet Earith

One of our local nature reserves has been created from retired gravel pits. It’s known as RSPB Ouse Fen and it’s split across three patches with some active gravel and sand excavations still underway in between*. One patch, the Needingworth side, I mentioned several years ago. The second patch, which is across the river via Brownshill Staunch, can be referred to as the Over end the more recently opened patch is at the village of Earith.

According to the RSPB website on the subject:

“…when the project is fully complete, Ouse Fen along with its neighbouring RSPB nature reserves; Fen Drayton Lakes and the Ouse Washes, will form a near continuous 3000 hectare wetland habitat, around half the area of the nearby city of Ely.”

We visit these places a lot. I’ve mentioned theem here a lot too, not least with reference to Short-eared Owls, vast Starling murmurations (half a million birds in March 2024), Clouded Yellow butterfly irruptions, and Chinese Water Deer (non-native, invasive species). The Earith section is a lovely spot, but often it’s quite quiet in terms of birds.

Today was different.

Black-headed Gull activity was high, first Common Tern of our year spotted, nine Hobbies catching insects on the wing, three or four Marsh Harriers courting on the wing, Water Rail squealing out of sight, numerous Little Grebe wabbling in the water. There were Grey Heron, Little Egret, Great White Egret, Coot, Moorhen, Kestrel, Rooks and Carrion Crow, dozens of Sand Martin, Pheasant, Blackbird, Whitethroat, Wigeon and numerous other ducks, Great Black-backed Gull, Leser Black-backed Gull, Linnet, Snipe, Redshank, Starling, Mute Swan (and according to the Merlin app, Bewick and Whooper, and Pectoral Sandpiper! Yeah, right!), Wood Sandpiper, Cormorant, Blue Tit, Lapwing, Oystercatcher, Canada Geese and Greylag Geese overhead, a few overheard Bearded Reedling and Sedge Warbler, Reed Buntings, lots of Cetti’s Warbler, lots of Reed Warbler, and we missed it, but last year’s Great Reed Warbler seems to have turned up again.

There were lots of Bittern booming and on our second fruitless pass of the GRW spot, we saw six Bittern ducking in and out of one patch of reeds. Most I’ve ever seen together in one sitting was two lots of two on the wing. It’s an amazing comeback for a once almost-extinct (in the UK) species. Its resurgence is largely down to conservation efforts and the creation of new wetland habitat from these ex-gravel pits.

Four of the six Bitterns that were in and out of this patch at RSPB Ouse Fen Earith

*The works have been running for a decade and have another twenty years to go. They take out something like 2 million tonnes of sand and gravel annually. I think they’re reporting that they’ve removed about 16 million tonnes in total so far. Other smaller gravel quarries in the area, such as the one even more local to us here in Cottenham, down Long Drove, have been back-filled and restored to arable farmland.