Biology – Page 25 – David Bradley

Glossy Ibis in Cambridgeshire

I’ve mentioned local sightings of an ostensibly African/Mediterranean bird before, the Glossy Ibis, they have been spotted at various RSPB sites Ouse Fen, Fen Drayton, Ouse Washes, and elsewhere in the last month or so. I saw a couple of them at Ouse Fen not long after one was first sighted by the warden and others there. There is evidence of perhaps five or maybe seven locally. It is worth noting that over the last decade or so, some of these birds which have begun breeding in Southern Spain have opted to spend their winters in The British Isles.

Three have now taken to feeding on the southern end of the Ouse Washes.

Oh, and there’s a bird that’s usually found in Asia in our locale too, a Dusky Warbler, Phylloscopus fuscatus, seen for the first time in Cambridgeshire in December 2020 at “The Boot” in Aldreth. I took a detour on the way home from snapping the three Glossy IbisÂ to see it, there were lots of twitchers, birders, and toggers around, but none had seen it at the time and I didn’t catch sight of it either…

The brand new moths of 2020

I have counted well over 300 species of moth in our garden this year(almost 9000 specimens), mostly at night, although there were one or two dayflyers (excluding butterflies, which are moths but are not usually listed as such). That is a small fraction of the total number of moth species listed in the British Isles which tallies at 2500 or thereabouts, 180,000 species of lepidoptera globally.

Of those 300 or so species about 30 were new to me having not ticked them in the garden before. Here’s a small selection starting with the rarest, the Clifden Nonpareil, a moth that was extinct in The British Isles by the middle of the twentieth century but is making a comeback.

The Wormwood

Siberian White-fronted Geese

Migratory geese in huge numbers arrive on our coasts in the winter heading in from Greenland, Iceland, Scandinavia, and even Russia. Some of them end up further inland as did this small flock of White-fronted Geese, Anser albifrons (Russian sub-species), which I photographed on farmland adjacent to RSPB Ouse Fen in Cambridgeshire. Friend Steve Rutt, author of Wintering, tells me that there has been an influx of the Russian race of this species.

The bird is bigger than a mallard duck but smaller than a mute swan. The head of the adults has a large white patch. They also have bold black belly bars and orange legs. The Siberian sun-species, pictured here, has a pink bill whereas the bill is orange in the Greenland bird. We have something like 13000 of these geese that winter from Greenland in the British Isles, the Siberian race is less common.

I got a couple of snaps of the birds on the ground from several hundred metres away before the farmer’s cropsprayer spooked them and they took to the air and headed west towards the river that divides this reserve.

The RSPB warden who gave me the ID on the geese also said a Brent Goose had been seen on the reserve and a couple of Whooper Swans. He added that there are at least five Glossy Ibis in the area. Regular readers will know I saw a couple of those rare African visitors at Ouse Fen a couple of weeks ago. There are three on Swavesey Lake. See also Cattle Egret and Great White Egret for birds ostensibly of African origin that are increasinly common in The Fens.

Egrets, I’ve seen a few – Cattle Egret

Back in the early 1990s, Mrs Sciencebase and I visited Botswana and Zimbabwe. It was wonderful. The people, the landscapes, the wildlife. There were so many superb species around such as Golden Weaver Birds, Oxpeckers, Superb Starlings, various storks, ibis, vultures, Fish Eagles, Eagle Owl, and Little Egrets (probably Cattle Egrets too).

We were quite confused on our return on a visit to the North Norfolk coast (a place that would become a favourite haunt) that we saw a Little Egret there. Over the next three decades or so little egrets seem to have become increasingly common in East Anglia and although it’s still lovely to see them, they’re almost commonplace. Five years ago the same couldn’t be said of another type of egret. The Great White Egret, but that too is becoming more common. Similarly, Cattle Egret (Bubulcus ibis).

Is it simply an effect of climate change? These ostensibly African birds spreading their wings and thus their range and reaching farther north with each passing year? Well, climate change is definitely playing a role in species distribution when it comes to birds and many other forms of life. But, it’s more subtle than that. Deliberately or inadvertent introduction of the Red Swamp Crayfish (Procambarus clarkii) in freshwater lakes across Europe is providing egrets of all flavours as well as cormorants and other species with a ready, but unaccustomed food source and this is allowing them to expand their numbers and their range. (Barbaresi and Gherardi 2000, RodrÃguez et al. 2005)

The presence of the introduced North American crayfish, often known as the freshwater lobster, in the lakes of Northern France now means those egrets that were so rare this far north have but a short hop across the channel and upwards into East Anglia where they will find food and a foothold in small numbers.

It is perhaps only a matter of time before the red swamp crayfish becomes widespread in the freshwater lakes of The British Isles too and those egret numbers will rise still further.

We saw five Cattle Egrets in Fen Drayton this morning, feeding in between the hooves of a herd of cattle. Last winter we saw a flock of some 60 or so Little Egrets in the reserve that abuts the village and I have seen half a dozen Great White Egrets there (alongside lots of Little Egrets and lots of Grey Herons).

It’s possibly the same phenomenon leading to more frequent sightings of Glossy Ibis in East Anglia lately too.

Local birds for local people

Sunday morning was bright, cold, a few streaky clouds in the sky, but sun shining through. We were not quite up with the lark, but we got booted up and headed out for a brisk walk at one of our local patches where we often see Kingfishers and various other bird species. River Great Ouse running through farmland and along the bank top of one of the lodes that drain the fens, once around a fishing pond. Was expecting to see maybe a dozen bird species, but we counted all of these and maybe a couple more for which we didn’t get a positive identification, little brown jobs (LBJs), in other words.

Blackbird
Blackheaded Gull
Blue Tit
Bullfinch
Buzzard
Chaffinch
Collared Dove
Coot
Cormorant
Dunnock
Fieldfare
Goldfinch
Great Spotted Woodpecker
Great Tit
Grey Heron
Grey Wagtail
Kestrel
Kingfisher
Linnet
Little Grebe
Mallard
Mute Swan
Pied Wagtail
Redwing
Reed Bunting
Robin
Rook
Song Thrush
Whooper Swan
Wood Pigeon
Wren

2020-11-23 UPDATE: Today’s outing was to the village of Fen Drayton to see the five Cattle Egrets that have settled there temporarily. We saw those birds and quite a few more besides, venturing only a little way into the RSPB bird reserve that is adjacent to the village. Today’s list:

Cattle Egret, Blackbird, Blackheaded Gull, Blue Tit, Chaffinch, Collared Dove, Coot Cormorant, Dunnock, Gadwall, Goldfinch Green Woodpecker, Kestrel, Mallard, Mute Swan, Pied Wagtail, Pochard, Red Kite, Redwing, Robin, Rook, Tufted Duck, Wigeon, Wood Pigeon

Local starling murmurations

Back in September, the number of starlings on farmland around the village seemed to build. It seemed early for the European winter influx, maybe it was just wishful thinking. I was hoping for large numbers that would begin to murmurate over the Broad Lane balancing pond before diving into their nocturnal roost in the reed bed there. (This particular video of mine was from November 2018)

Other concerns took over my thought processes, as they are, in October and early November, and I’d all but forgotten about the starlings by the time the local birders started pinging me about rising numbers 30 to 20 minutes before sunset over the pond. When I finally got the opportunity to check out the swooping and swirling of these maestros of social distancing, the murmurations were occurring most evenings and the numbers, I and birding friend Neil (watching at two-metres distance) estimated there were about 6000 there. Quite an amazing sight and the whooshing as they soar close overhead before diving into the reeds is astonishing. The next evening, the numbers had grown, perhaps to around 7000.

That was the peak for Cottenham’s murmuration. Over subsequent nights and having shared video on social media and mentioned to a few friends, the numbers began to decline as the number of observers rose. At the human peak, I think there were about 20 people, adults and children and a few pet dogs, waiting patiently for Dave’s Spectacular. It hadn’t happened in Cottenham again as far as I know. Another friend, Liz, reported that their daughter suggested 12 starlings wasn’t quite what you’d expect from Sir David…

Meanwhile, the Cottenham birder list alerted me to a large number at RSPB Fen Drayton, some 7000 birds were murmurating there over Elney Lake. It could easily be the same flock that apparently had departed Cottenham. There was also a peregrine falcon there hunting through the flock. Indeed, murmurating is flocking behaviour to reduce the risk to the individual bird being predated by such raptors ahead of bedding down for the night. I got a little distant video footage of those birds.

Also to be seen at Fen Drayton, four cattle egrets, birds that until recently were rarely seen in the British Isles, but whose numbers like those of the Little Egret and Great White Egret, ostensibly “foreign” birds have been growing over the last couple of decades. Climate change may well be playing a part in how such species are extending their range.

The story doesn’t end there. We visited RSPB Ouse Fen (Reedbed Trail side, accesses from the car park at the Over edge) one morning in mid-November. The RSPB warden – Hannah Bernie – was still there with her team hacking back reeds with a view to increasing plant, and thence animal, diversity on the reserve. She told us that they had spotted another rare visitor, a glossy ibis. The bird had been spotted at Fen Drayton a couple of nights before, but had flown, and this was presumably the same bed making Ouse Fen its temporary home. One birder I spoke to on the day I saw the GI told me he’d seen five or six on the reserve during the last decade or so.

The warden also mentioned in passing that they had a large starling murmuration of about 10000 birds. I felt obliged to return that evening to witness the spectacle. That night I would estimate that there were at least twice as many birds as there had been at Cottenham’s peak, so perhaps 14000.

Of course, such numbers are minuscule compared to other murmurations such as the knot (a wader, or shorebird) that one sees at this time of year, hopping the tide at RSPB Snettisham in North Norfolk. We saw 68000 of those birds there in September and the numbers had doubled by late October. And those numbers are dwarfed by the multi-million strong murmurations one might see in the original sub-Saharan homes of some of those “foreign” birds I mentioned. Where vast, entrancing murmurations swoop and swirl above the cattle egrets pecking at the feet of herds of majestic wildebeest. Still, we must enjoy the nature to which we have relatively easy access, especially in times of covid.

Sir David Attenbradley

Glossy Ibis – Plegadis falcinellus

UPDATE: As of 2020-12-08 there have been sightings of about seven Glossy Ibis around the area at RSPB Fen Drayton, Ouse Fen, Ouse Washes, at Earith Sluice, and elsewhere. This is almost an irruption!

You don’t expect to turn up at a Cambridgeshire wildlife reserve to be told by the warden (Hannah Bernie) that there’s an African bird species hanging around. But, in early November, that’s what we heard at RSPB Ouse Fen. Actually, I’d heard that this species was at RSPB Fen Drayton, but I’m not a real twitcher so hadn’t gone out of my way to see it there. We were actually there on a fairly calm day to see if we could sight the Bearded Reedlings.

Warden Hannah told us there was a Glossy Ibis, Plegadis falcinellus, present and it had been seen but it was lurking behind the reeds at the time. She also mentioned a 10000-starling murmuration the night before. I visited the same sight later that day and reckon there are 14000 starlings murmurating there.

Anyway, back to the GI, we didn’t see it and we only heard Beardies. So I headed back again today, I usually visit once a week. Parked up and within 200m of the car, there it was, on the edge of the reeds. Apparently, a birder had predicted one might turn up, the RSPB having cleared a lot of old reeds from these former gravel pits. I got a few record shots, nothing clear nor sharp.

Fellow walker – name of Richard – with a birding ‘scope, stopped 2-3 metres away from me as I was snapping the bird on my return pass. He mentioned that they are not as rare as one might imagine in the British Isles these days. He said he’d seen them five or six times over a decade of visiting this reserve. Given that other African birds – Little, Great White, and Cattle Egret are also rising in numbers here we mused on how even the most casual birders are no longer as impressed as they once were at the sight of such species. Indeed, the presence of a Whinchat or a Pied Flycatcher might be more exciting than any Egret or even the GI, amazingly.

Climate change will definitely be driving the northwards flights of these birds which originate in sub-Saharan Africa but are spreading their range. But, Richard also mentioned that the accidental introduction of Red Swamp Crayfish (Procambarus clarkii) to lakes in northern France had provided a lot of food for such species and they are thus much further north partly because of that. It is only a matter of time, perhaps, before that invasive crustacean finds a niche in the former gravel pits of East Anglia and we begin to see even greater numbers of these African birds settling in this part of the world.

First time I saw a wild Glossy Ibis was in Botswana in the early 1990s, if memory serves. Most recent sighting was on the edge of a former gravel pit in a windswept patch of South Cambridgeshire.

Noc Mig Redux

Months ago, at the beginning of lockdown 1.0 I think I mentioned nocmigging. It’s the nocturnal audio recording and analysis of overnight sounds that might include the calls of migrant birds flying overhead. In April, I set up a microphone and recording software and poked it out of my office window and left it running overnight. In the morning I checked to see what had recorded and sadly it seemed at the time that the software had failed and all I had was the first 20 minutes from when I set things running.

NocMig recording in Audacity Spectrogram view showing the rise of the dawn chorus, 2020-04-07

I had tried a few more times and had managed to record the dawn chorus once or twice, but I didn’t think I had captured a long period of nocturnal noises until I was scanning my hard drive with the aim of deleting unwanted large files to clear some space. I found a 6h45m 4.5 gigabyte audio file. Exciting stuff.

So, now processing with Audacity in spectrogram view with the aim of feeding the output into the nocmig software. Here’s how to configure audacity for a nocmig recording.

Turns out there’s very little to hear other than occasional motorbikes and cars, at least until the first Blackbird of the dawn chorus, followed by Robins, Dunnocks, Wrens, and Wood Pigeons. Nothing was apparent and high-pitched in the spectrogram during the preceding hours. And, an audio scan didn’t even give me muntjac, foxes, nor even cats in the night, possibly one very distant dog barking. It was all very quiet, sadly. Still, there’s always next year.

Catocala Underwings

UPDATE: Greece, June 2024 – Added Catocala nymphaea to my list of photographed Erebid “underwings”.

Catocala nymphaea moth with its orange and black marked hindwings

UPDATE: New Forest, 25 Aug 2022 – I finally trapped the Light Crimson Underwing (Catocala promissa) at our holiday house in North Poulner, Hampshire, which completes the British set for me, I believe. There’s a short video clip of the LCUW on the Sciencebase Instagram, with Going to the Chapel as the background music for good reason.* In the summer of 2023, Adrian Matthews caught an LCUW in Chesterton, a first for Cambs.

The Catocala moths are a group of relatively large moths in the family Erebidae. They are often known as “underwing moths” because of the intriguing colours and patterns of their hindwings, which are usually hidden from view under the forewings while the moths are at rest and only revealed either in flight or when the insect is startled.

Not to be confused with dozens of others species in the Noctuidae that have the word underwing as part of their common name (e.g. Yellow Underwing, Straw Underwing, etc) and Geometridae (Orange Underwing).

Clifden Nonpareil, Catocala fraxini, the Blue Underwing

These large Catocala underwings are not common in The British Isles and where they are known are often localised to particular niches. In my time mothing since late July 2018, I have trapped, photographed and released three of the group: Red Underwing, Dark Crimson Underwing, and the (once extinct here) Clifden Nonpareil (the Blue Underwing). Actually, I had the Red in the garden in 2019 and then saw it a few days later on a camping trip to the eastern coast of Norfolk.

I am yet to see the Oak Yellow Underwing, the Rosy Underwing, the Minsmere Red Underwing, or the French Red Underwing. There are 30 Catocala species in Europe and 250 globally.

*Interesting to note that they all have scientific names alluding to nuptials and wedding nights. The naturalists who named them, whimsically imagining that the brightly coloured hindwings were like a bride’s brightly coloured bloomers! So we have C. sponsa, C. nuptia, and C. promissa. The Clifden Nonpareil is the exception, its scientific name, C. fraxini, alluding to the ash tree, wholly inappropriately as its food plant is the aspen.

More moths, birds, and other nature shots via the Sciencebase Instagram, please join me there.

Clifden Nonpareil, Catocala fraxini (Linnaeus, 1758)

Clifden Nonpareil – For the incomparable moth from Clivedon House, blue is the colour!

Blue is not a common colour in British moths

The UK Moths website described Catocala fraxini as the Victorian collector’s classic all-time favourite”. It also goes by the name of the Blue Underwing because of the shock of blue on the hindwings, which are usually covered by the forewings when the moth is at rest and are exposed when it reacts to a threat.

C fraxini feeds on aspen rather than ash (the frax of its name)

The moth was well known in the British Isles in Kent and Norfolk until the middle part of the the 20th century, the site explains, but it ultimately became extinct in terms of being a breeding resident on these shores and was seen only occasionally by lepidopterists as a vagrant immigrant from the continental mainland.

Thankfully, the species has been gaining new traction in the South of England and in East Anglia. It is now thoughtto be recolonising and is almost certainly breeding in the south. As an amateur moth-er, I hoped to draw this species beyond compare to the actinic lure I light up some nights in our Cambridgeshire garden. I didn’t hold out much hope until I heard on the mothing grapevine that there had been one or two sighted in neighbouring counties.

Blue Underwing with my secondhand copy of Manley behind

Then, in the middle of August, a fellow moth-er at the other end of our village here, reported a sighting of a Clifden in his garden. At the time, the closest I came to the fabled Blue, was another Catocala species, the Dark Crimson Underwing, that came to the actinic lure (it’s just a UV lamp, by the way). The Dark Crimson is usually confined to the New Forest, I was happy to see it.

A couple of weeks later my village friend reported a second Blue and his own NFG (new for the garden) Dark Crimson. I had my fingers crossed as tightly as they can be, but no luck. The autumn kicked, in then a mini-heatwave or two. There were endless Large Yellow Underwings (which are unrelated to the Catocala species, being Noctuidae rather than Eribidae. There were also lots of Lunar Underwings, yet another noctuid with veiny forewings and a moon-like crescent on each hindwing. Lots of Square-spot Rustics too and the Black Rustics of autumn. But no Blue.

Finally, on the night of 28th September at about 22h50, I let the dog into the garden for her late-night ablutions and checked the actinic lure, immediately spotting lots of craneflies on the adjacent wall, a Lunar Underwing on the box itself and…oh…there…an enormous speckled, patterned, grey moth with its shimmering band of blue on each hindwing exposed when the moth is disturbed. It truly is beyond compare, nonpareil.

This specimen was a little battered by the time it reached my lure. It is about 48 mm from palps to the tip of its folded forewings. The books describe it by wingspan which can be 80 to 90 mm. For a British species, it is truly enormous and impressive, not quite as big as our largest resident the Privet Hawk-moth which can be up to 120mm when its wings are fully expressed.