Science – Page 10 – David Bradley

Feed the birds…twenty quid a bag…

Food for the garden birds is rather pricey. Certainly not the tuppence-a-bag of the song from Mary Poppins. Admittedly, the bags you buy are a lot more heavily laden with various seeds and grains.

Anyway, discussion is ongoing in my Wild Fen Edge group about when to feed garden birds, so here are some thoughts.

Birds need to eat all year round. So, I put food out all the time – mixed seed peanuts, nyjer seeds, fat balls, flutter butter. Different places in the garden, different heights if possible, near obvious perching points, higher than cat access, some out in the open. Also, not too many feeders close together to avoid disease. Feeders should be emptied and cleaned thoroughly with detergent on a regular basis.

I also have a couple of bird baths of different sizes (one on the ground, one on a stand) and a pond for their drinking and bathing. Birdbath water needs to be changed frequently as the birds commonly add droppings.

I have written about attracting birds to your garden previously, so check out that for more tips and tricks. I’ve seen at least a couple of dozen species in our garden over the years, including the common birds, but also the likes of Grey Heron, Great Spotted Woodpecker, Fieldfare, Redwing, Chiffchaff etc.

An additional point about gardens, native wildflowers are great for insects and so the insectivorous birds. Leave your garden a bit scruffy. Let a few weeds sprout. Create some wild patches, don’t have gravel and lawn throughout and never, ever, ever put down astroturf, you Philistine! Let standing stems go to seed at the end of summer and don’t prune them back until they begin to rot or the birds have emptied them of seed. Stick to #NoMowMay and let it run into June. Also, do #NoPruneJune and basically avoid being overly tidy with your garden. The more scruffy bits, overgrown, weedy, diverse, the more chance of attracting and keeping invertebrates and birds. Let your bushes and ivy produce their berries, these will feed Blackbirds and the like in the winter. They might even attract Fieldfares and Redwings…maybe even Waxwings, if you Rowan (Mountain Ash).

The natural approach is perhaps best and maybe not even putting out food should be the way to go. But, there are two arguments about feeding garden birds one for and one against

The first says we shouldn’t really do it at all, as it brings birds together and can spread disease. Garden feeding can alter behaviour in terms of how birds feed so that some might become reliant on feeders rather than seeking out natural sources of food. There are also issues with the numbers of chicks Blue Tits and some other species are raising and out-competing other local species because they have adopted feeder feeding quite vigorously. Feeders are even thought to have altered migration patterns, viz the over-wintering Blackcaps we now commonly see in English gardens.

The second school of thought suggests that because we have removed the birds’ natural habitats and reduced greatly the numbers of insects on which they would feed through agriculture and development, we need to provide them with alternative habitation and food all year round. Our gardens can offer that.

So, personally, I feed all year round with a few caveats. Such as if I spot an obviously diseased or dead bird in the garden, I’ll remove all feeders, empty them into the bin and give them a good scrub in hot water with detergent. I’ll dry them and put them away for a couple of weeks, to dehabituate the birds to my garden for a while. It’s also a good idea to remove feeders if you see rats. Although rats are perhaps more attracted by bread and meat scraps or cheese. These are not the best choice for bird food anyway, so best not to put those out on bird tables or in feeders.

(Almost) 500 moths in five years

As I approach my fifth anniversary as a mother, my tally shows that I have recorded and photographed almost 500 species. The most recent was new to my garden – The Leopard Moth, Zeuzera pyrina.

Leopard Moth. Its forewings with flapping very rapidly, but flash and a fast shutter froze teh action

There are several things of interest about this moth aside from the fact that it’s fairly large and white with spots of black (almost metallic blue, in some cases). First is that the adults, the flying creatures, as opposed to the larvae (caterpillars) have no working mouth parts and so cannot eat. There are several other species, such as the Emperor, which are in a similar predicament, as it were. They are to all intents and purposes flying sex machines and nothing else, to be frank.

Sideview of the Leopard Moth, not the structure of the antenna

A second point of interest to me, is that with a quick glance you can see that the males have feathered sensory antennae, they resemble those of the Willow Beauty males. But there is an important difference in structure. Where the Willow Beauty antennae resembles a feather along its length, the Leopard’s antennae are feathered half-way along their length and seem to end in a bare spine.

Now, the really interesting thing about the Leopard Moth, as pointed out to me by uber-mother Leonard Cooper, is its lifecycle. Once mated, the female lays clutches of eggs in damaged areas of bark in the larval foodplants (deciduous trees). The larvae hatch from the eggs and begin burrowing deeper into the wood, they tunnel out feeding galleries, eating wood (they’re xyophagous) and leaving frass (poo) in their wake. If the adults are flying sex machines, then the larvae are burrowing food machines.

Bird's eye view of a Leopard Moth, the spots presumably confuse them into imagining the moth is nothing edible — Bird’s eye view of a Leopard Moth, the spots presumably confuse them into imagining the moth is nothing edible

Once they’ve had their fill and by some conditional trigger, the larvae burrow through the wood and then pupate just under the bark. Presumably, they find a damaged patch so that once they have completed their metamorphosis within the pupal form and are ready to emerge as adults, they can spread their wings and fly off to find a mate. To do so they will use up the food reserves built up during the time they were very hungry caterpillars. In the UK, you might see adults in flight from June to July.

Oh, when I said “very hungry caterpillars, they can spend two or three years feeding in the galleries they create within the stems and branches of the tree before pupating. Now, several moths overwinter as larvae or pupa. The Leopard is not quite exceptional in that it lives so long as a larvae, perhaps up to four years rather than just 2-3 years, the Goat Moth, too spends a long period within the trees, I am sure there are others.

As to my mothing for five years, do you seriously think I am looking for a new pastime? Do Leopards ever change their spots?

Of moths and box

This is a female Box-tree Moth. They were inadvertently brought into the UK in 2007 on imported, exotic Box plants. They are spreading rapidly and I see lots in Cottenham. I don’t think they’ve got as far north as Ely yet, but it’s only a matter of time.

Female Box-tree Moths lack the male's hair pencil at the end of the abdomen — Female Box-tree Moths lack the male’s hair pencil at the end of the abdomen

The female lays her eggs on Box plants and her larvae will ravage the plant, you’ll see the damage pretty quickly. In their native environment the moths are kept in check somewhat by the ecosystem itself, but that doesn’t happen here. I have warned people not to plant Box here any more…it will be eaten…even established hedges will succumb. Please don’t spray pesticides around, pesticides are nasty, and I say that as a chemist. If you really want to try and save the hedge pick the caterpillars off by hand and “relocate” them…

You can buy a pheromone trap, a plastic flask, often green and yellow, and you put a little rubber bung in the top. The bung carries a tiny quantity of the female sex pheromone. You hang it near your beloved Box hedge and it attracts the males who are suckered into going into the trap thinking a female awaits…they can be drawn in from up to about ten miles away.

Sounds like a cunning plan, doesn’t it? But, think about it. The females are all over the place, and most likely on your hedge, to which they’re drawn because it’s their larval food plant (hence the name!). There may well not have been males in your street, but you’ve just put out a big chemical communication and invited them to the orgy…even if you catch a handful in the trap before they mate, chances are you won’t catch them all, and it only takes one for your local female to have a clutch of fertilised eggs ready to lay on your hedge. Her very hungry caterpillars will feast on it soon enough…

You can distinguish between the male and female moth, because the males have a tuft at the end of their body known as a hair pencil, it’s basically a diffuser for their own pheromones. There is also a melanic form of this species, which is dark brown-purple where this one is white.

Brampton dragonflies and butterflies

I only occasionally photograph dragonflies and damselflies, the Odonata. My big zoom doesn’t give me the best results with these insects for some reason. However, I was at Brampton Wood yesterday to see the recently emerged Black Hairstreak butterflies. Took a shorter zoom, Canon 75-300mm for that job instead of my Sigma 150-600mm and tried my chances on snapping some dragonflies in between hairstreaks.

First in the frame was this lovely Black-tailed Skimmer, Orthetrum cancellatum. What a great scientific name.

Black-tailed Skimmer dragonfly - Orthetrum cancellatum — Black-tailed Skimmer – Orthetrum cancellatum

And, here’s a male of the relatively common species Broad-bodied Chaser, Libellula depressa, coming into land on a stick protruding from Wayne’s Pond at Brampton Wood.

A Four-spotted Chaser, Libellula quadrimaculata, favoured the perching sticks in the pond too.

Four-spotted chaser, Libellula quadrimaculata, with its eight spots! — Four-spotted chaser with its eight spots!

Another interesting dragon at Brampton Wood is the relatively rare Green-eyed Hawker, Aeshna isoceles. The isoceles is a reference to the yellow triangle on its second abdominal segment. It has an alternative vernacular name, Norfolk Hawker, this common name in the UK refers to its lasting presence in the county of Norfolk, although it was common in the Cambridgeshire Fens until the 1980s. It is now known to exist in Suffolk and Kent, but is localised and scarce.

However, old Green Eyes is back…in Cambridgeshire. Although it remains fairly elusive; it always was a rarity. Perhaps the species is benefiting partly from the creation of numerous wetlands on the sites of old gravelworks in the county, such as RSPB Fen Drayton. It favours ponds, ditches, and marshes with dense vegetation and seems to rely on the aquatic plant Water-Soldier, Stratiotes aloides. There’s plenty of that in my garden pond, so fingers crossed and there is obviously something about Brampton Wood they like too.

In non-dragonfly news, also spotted a Bumblebee Plumehorn, a type of hoverfly, Volucella bombylans.

There were Brimstone and Garden Grass-veneer moths to be seen and Spindle Ermine and Pale Eggar moth nests, a few scattered Large Skipper butterflies on the site as well as several Speckled Wood butterfly. Also at play numerous Longhorn Beetle, a few European Hornet, and a lot of Green Oak Tortrix moths, Tortrix viridana. They’ve been coming to traps in large numbers during the last few days around Cambridgeshire, so it was no surprise to see them on the oaks in Brampton Wood.

Green Oak Tortrix moth on green oak leaf

However, my target species for the day was the Black Hairstreak butterfly, Satyrium pruni. I estimate I saw 40-50 over the course of the visit. Although the butterfly is nationally very rare, it is present on this site and other ancient woodlands with well-established Blackthorn (Prunus spinosa) to the west and southwest in huge numbers. There were several within yards of the site entrance, one or two along the main ride, several on blackthorn near the aforementioned pond, and several on the two sites marked for visitors to observe them. I got photos of perching and puddling butterflies, some ovipositing females, and caught sight of a mating pair, but didn’t get the money shot of that coupling!

The Black Hairstreak was not known as a species until 1828 when a professional entomological dealer, Mr Seaman, charged with gathering up specimens of the rather similar White-letter Hairstreak delivered these to his patron only to discover a novel species among the White-letters. Edward Newman, a Victorian entomologist of note, declared the novel species to be the Black Hairstreak. Monk’s Wood, like Brampton, is an ancient woodland with a lot of old Blackthorn growing on heavy clay soil, just what the Black Hairstreak needs for its life cycle.

Another Black Hairstreak with a wing problem allows us to see the dark-brown upperside of the forewings with their orange-spotted fringe. Usually, it is very difficult to see the upperside of the wings as the insects invariably close their wings together when they land. It is worth noting that non-native Muntjac deer can be a voracious nuisance in this kind of ancient woodland. If it is allowed to graze freely in such habitat, there is the potential for rare, native species that rely on the habitat to be lost. As I understand it, at least one of our nature conservation organisations is involved in culling Muntjac where it is roaming freely in such habitat for the sake of conservation of the sensitive native species.

Black Hairstreak revealing a little of the upperside of its wings

Not to be confused with a butterfly of the Americas, Ocaria ocrisia, with the same vernacular name, that also goes by the monicker Hewitson’s blackstreak.

One final thing – Common Spotted Orchid, Dactylorhiza fuchsii.

Mothing addiction and the meaning of mothing

I acquired another moth trap to go alongside my old second-hand, home-made Robinson with the 40W actinic UV fluorescent U-tube, the portable 20W UV fluorescent Heath, the LepiLED, and, of course, the pheromone trap for the Emperor moth and the clearwings.

The day-flying Yellow-legged Clearwing moth has evolved to resemble a wasp in order to avoid predation

I crammed it with the usual stock of roosting options for the moths, a load of empty cardboard egg cartons, and lit up.

A collapsible Skinner moth trap with 20W Wemlite, UV bulb, and rain guard — Skinner moth trap

It was 11 Celsius last night, a degree cooler than a recent lighting-up session, but the new trap brought a fairly good haul, 28 moths of 18 species, with several new for the year (NFY), although no new for me or new for the garden (NFM or NFG). These are the highest numbers of the year so far, although the good numbers on nights of a similar temperature recently have not been far short.

The Shears moth, so-called because a detail in the pattern on its forewings resembles a pair of sheep shears

The Skinner trap is basically a box with slots in which two Perspex sheets are slid to form a groove with a narrow gap. A UV light is held above. Moths (and a few other nocturnal insects) are attracted by the light and with luck fall through the slot and on to the pile of egg cartons where they settle for the night. In the morning, preferably before dawn when insectivorous birds awaken, the diligent mother-er will check the contents of the trap. Not species and number, perhaps take photos, and then later in the day release the moths safely, off-site into the new dusk. Records are shared with one’s County Moth Recorder (CMR) for scientific purposes.

Toadflax Brocade moth, the name comes from the larval foodplant, toadflax, and the resemblance of the wing patterns to richly decorative woven cloth, brocade

The Heath and the Robinson traps are similar, but have a funnel instead of a slot, which purportedly leads to fewer escapees. The Heath is usually small collapsible, and so more portable than a Robinson.

This is the quite diverse list from last night’s haul, one each of each moth unless otherwise stated: Bee Moth, Brimstone, Celypha striana NFY, Common Pug, Garden Rose Tortrix NFY, Heart & Dart 4, Large Nutmeg, Light Brown Apple Moth, Light Arches NFY, Light Brocade 2, Light Emerald 1, Minor agg 2, Shuttle-shaped Dart 2(M), The Shears NFY, Toadflax Brocade NFY, Vine’s Rustic 3, White Point 3, Willow Beauty 1.

Various moths in an egg carton from the moth trap

There are some who argue that this hobby, albeit a scientific one, is somehow cruel. That we are depriving creatures that live only a short life of one night of their season. And, that we should leave them to themselves. Well, far more cruel is the wanton destruction of the habitats in which these creatures live and the often shameless use of pesticides.

Male Emperor moths can be drawn to a pheromone lure for scientific purposes — Male Emperor moths can be drawn to a pheromone lure

However, without people monitoring species, keeping records, collating them, and studying the trends, we would not have a clue as to what we need to protect from the destruction, and how we might do that. We know from these mothing records that many species have declined considerably over the last half century or more. But, we also know that some species once thought extinct have thankfully risen from the scorched fields to grace our gardens and other habitats again. We also now know more about how some moths migrate and where from. In addition, we also know, often from the pheromone trapping, that some moths, the clearwings and various micro moths, once thought absent in particular areas are present there after all and perhaps more widespread than we ever imagined.

The surprising sight of a bat flying at midday

Oh, and one more thing. A bat will consume 300 or so flying insects every night, so the impact of even the most efficient and effective moth trap in the garden is negligible in comparison. Indeed, one might say, they are saved from predation if they find those egg cartons before the bats find them!

The White-point moth

TL:DR – The first White-point of my mothing year in the garden 4th June 2023.

The White-point (Mythimna albipuncta) is one of the moth species we refer to as the Noctuidae, the owlets. It has perhaps the most obvious of names given its appearance.

The White-point is an immigrant species to the British Isles, primarily found in the southern and southeastern regions of England, although it is seen in Norfolk. I’ve had it numerous times in my Cambridgeshire garden over my five years of serious mothing.

In some years, hundreds are reported and there is some evidence that it might even breed here in good years, although whether that has led to established colonies is not yet known. One might posit that its presence increases overall diversity, but that would only really have a significant long-term impact if it were to establish itself as a breeding species in the UK. That said, it, and its larvae, might already be providing food for other species, such as omnivorous birds, mammals, and amphibians and as such affecting eco-systems in a small way. Its larvae feed on various species of grass.

The species usually flies from August to September, but can be seen on the wing at any time from June into October. It is common across Europe.

Black Terns on a camping trip

TL:DR – Record shots of the three Black Terns at a local RSPB reserve.

They say that one good tern deserves another, if you’re talking comic terns. So, when you go looking for one and three come along all at once it’s quite amusing.

As I mentioned in a previous post about processing low-light photos, we were camping, locally…so local in fact that when three Black Terns were mentioned as being present on Ferry Lagoon at RSPB Fen Drayton it was only a short hop from RSPB Ouse Fen where we were camping to get a view of them.

Of course the birds were fishing in the waters there at a distance from the closest viewpoint of between 250 and 300 metres. Quite a distance to look through even a 600mm zoom lens or binoculars, especially on a dull grey day. But, we saw them. regular readers might recall the American Black Tern we chased around Northumberland to see in 2022. The American is Chlidonias niger surinamensis and as far as I know there have not been any sightings of the sub-species in the UK this year. The Black Terns we were watching on Ferry Lagoon are the parent species Chlidonias niger.

As is the wont of vernacular names, there is often only an element of truth in them. Indeed, the Black Tern has a grey, if not blue appearance about its wings, a white rump and a sooty head and almost black bill, at least in its breeding plumage, it is perhaps blacker out of season.

Diving Black Tern — Black Tern diving, although the books say they don’t dive for fish!

The bird generally fishes on inland water in Europe, Western Asia, and North America. It has a couple of old names, “Blue Darr” (Blue Tern) and “Carr Swallow” (Lake Swallow). The genus name comes from the Ancient Greek, khelidonios, for swallow-like, while the species name, niger means shining black.

I had seen one once before, but briefly, perhaps summer of 2018, flying over the Reedbed Trail area of RSPB Ouse Fen. As I check Birdguides for sightings there are others present in ones twos, and threes all over England. The bird was once common in the Fens, but drainage led to its local extinction by about 1840. It’s wonderful to see it flying here where gravel pits have been morphed into nature reserves as with Ouse Fen and Fen Drayton.

Processing photos at dawn

TL:DR – Photos taken in very light with an old camera are never going to come up to snuff unless you use a denoise app like DxO’s PureRaw 3.

We were up early from our camp bed near Ouse Fen on Bank Holiday Monday. The aim was to get on to the RSPB reserve and observe at dawn. The Bitterns had boomed through the night and one or two were still calling when we timorously made our way through the chill (just after) dawn air, it was 5am.

Mrs Sciencebase spotted a solitary Bittern crossing from reedbed to reedbed, the wont of females I believe, homing in on the blown-bottle sound of the males cryptically tucked away among the reeds. So, here she is, the unprocessed shot on the left saved from RAW format from the camera and untouched.

To get the image on the right, I applied the denoising abilities of DxO PureRaw 3, which I think cuts about three “stops” of ISO. I exported it from that app as the portable RAW format known as DNG. This allowed me to open it as if it were a file straight from the camera in PaintShopPro and so start afresh with the denoised file.

PSP has a RAW importer that does what the likes of Lightroom do so you can rescue blownout areas in photos with that issue or correct overall exposure. In the case of the Bittern shot taken with very low light levels, it needed a maximum lift from the dark and dingy DNG file. Once in PSP, I did my usually tweaks, raising brightness a tad, adjusting shadows a little, a spot of highlight boost, a tiny bit of a vibrancy bump, a little application of an unsharp mask, and then a crop.

It’s not too bad a record shot. I have better images of Bitterns in flight taken on sunny day on this and other reserves.

I got the Small Blues at Magog Down

TL:DR – Late May and there are lots of tiny butterflies known as Small Blue at a local nature site, Magog Down, south of Cambridge.

It could have almost been a serenade to lepidopteral melancholy if I’d chosen to seek out butterflies at Trumpington Meadows* this morning, it’s not been a good season for butterflying there so far it seems, but instead it’s a celebration as I ended up counting dozens of Small Blue (Cupido minimus) at the equally serene but far more undulating Magog Down.

Magog Down in full bloom — Magog Down in almost full bloom

The site is almost opposite Wandlebury where Mrs Sciencebase reckons we may have seen one of the rare blue butterflies many years ago (perhaps a Chalk Hill or a Small).

A Small Blue butterfly, Cupido minimus. Not to be confused with any small, blue butterfly

I must confess, on arriving I was expecting to have to seek out tiny patches of Kidney Vetch among the Oxeye Daisy, Sainfoin (Onobrychis viciifolia) and other species across the acres. But, within a couple of yards of the gate, I spotted a couple of Small Blue on the ground and got a couple of record shots.

Walking on, it soon became obvious there were lots of Small Blue here, far more than I’d seen in 2022 on the Kidney Vetch patches at Trumpington Meadows. There was one cluster of the butterflies flitting about within a square foot patch and were not at all disturbed by my presence nor the endless clicking of the camera. Indeed, several landed on the camera, on the camera bag, on my legs, on my hands, and were happy to take part in a video shoot for my Instagram.

A Small Blue butterfly puddling on my finger, probing with its proboscis to find moisture and nutrients. They usually do this on animal poo!

I spoke to Andrew Knights, one of the Magog Down butterfly recorders, who had just finished a transect count. He’d ticked 94 Small Blues on a small patch of the area over the course of an hour, which suggests that there are probably hundreds if not thousands overall. This was, he told me, well up on last year’s transect numbers (50-ish). It was an entirely happy coincidence that I was there at peak Small Blue! County Butterfly Recorder Ed Pollard, had messaged in to say numbers at Trumpington Meadows were still shockingly low this week.

Squaring up or just trying to puddle together on a grass stem

I also saw lots of Holly Blue, Brimstone, Whites, several Small Heath, Brown Argus, possibly a Common Blue, and a Mother Shipton moth (pointed out by path-mower Nick Beale). Didn’t see any of the reported Green Hairstreak here. The site is well worth the visit and nice to get these kinds of blues when you’re on the down!

*At the height of summer, Trumpington Meadows is also wonderful for moths and butterflies: Marbled White, Common Blue, Brown Argus, Six-spot Burnet, Brassy Longhorn, Burnet Companion, Mother Shipton etc.

Searching for Dingy Skipper, Erynnis tages, at Devil’s Dyke, Cambridgeshire

TL:DR – I ticked a new-to-me butterfly, Dingy Skipper, at Devil’s Dyke near Newmarket this month.

The weather picked up mid-morning here in South Cambridgeshire, so I pinged my photo buddy Andy to see if he fancied taxiing me to Devil’s Dyke to seek out the cluster of Dingy Skipper butterflies not by others at this chalky embankment adjacent to Newmarket Racecourse. He did and within seconds of stepping on to the Dyke, we’d seen our first Adonis Blue (a presumed introduction dating to some time during the first lockdown). There were several Brimstone and a few Whites within the first few steps too.

Adonis Blue butterfly at Devil's Dyke — Adonis Blue butterfly at Devil’s Dyke

We had to walk a bit further to pick up more Adonis Blue of which we probably saw several dozen over the course of 2-3 hours. Also Common Heath and Yellow Shell moth and one or two micros. Numerous Brown Argus and Small Copper butterflies along the banks. There is no Field Scabious in bloom yet and no sign of Marbled White nor the more common here, Chalk Hill Blue butterflies.

Male Brown Argus, not to be confused with females of various “blue” species, the diagnostic is: if it’s looks a bit like this and has a long thin abdomen, then it’s a male and can only be a Brown Argus

But, we had success with the Dingy Skipper, Erynnis tages, which is new to my butterfly list, the first “NFM” for me in 2023.

Dingy Skipper, Erynnis tages, butterfly on chalk footpath, Devil's Dyke, Cambridgeshire — Dingy Skipper, Erynnis tages, butterfly on chalk footpath

Different angle on Dingy Skipper, Erynnis tages

Now, you might be wondering where we draw the line between moths and butterflies, the Dingy Skipper certainly has a moth-like appearance, especially when compared with something like the Adonis Blue. Indeed it looks rather similar to the Common Heath moth. But, there is no line between butterflies and moths. Butterflies, as I’ve said here many times before, are simply one branch on the moths’ family tree, with equal footing to other Lepidoptera groupings such as the Pyralids, Erebids, Geometrids (inchworms), or the Noctuids (owlets). Butterflies are moths. Asking what’s the difference between a butterfly and a moth is like asking what is the difference between a ladybird (ladybug) and a beetle…