Sussex Rarities – Hairstreaks & Clubtails

This morning, having heard some exciting news on the website of the Sussex branch of Butterfly Conservation, I found myself in Ditchling Common Country Park, scanning bracken after bracken with my binoculars. I was looking for a Black Hairstreak or two. The windy and overcast conditions were not conducive to my hopes of sightings along the lines of the day-count of 98 that was made earlier in the month!

These numbers are quite extraordinary considering the fact that this species was only confirmed to be found in Sussex just over a week ago. Following a few battered individuals found at the same site last year, a survey has been undertaken to determine the presence of this colony. Its appearance here is particularly notable as this site is far from the existing distribution of this species in the UK. It is thought to be confined to a band of clay soil in the Midlands, mainly Cambs, Northants and Oxon.

The closest Black Hairstreaks have previously come to Sussex is Surrey, where they were introduced in the middle of the 20th century. However, the habitat at the introduction site was destroyed and the species disappeared there. The species is not known for their long distance movements or dispersal at all, in fact patches of identical habitat to where they are found elsewhere on the same site often go uninhabited due to the reluctance of the butterfly to travel long distances. Therefore it is thought that this colony is also an introduction similar to the Surrey one, although despite it only being discovered very recently it is likely that the species first appeared in the 1990s – this is because the expanse of the population at Ditchling Common suggests that it has been expanding for quite a while. It’s so slow that the rate of expansion, even of a healthy population, is estimated to be only about a kilometre per decade!

Now, back to this morning. The foodplant of the Black Hairstreak is Blackthorn, and it was in abundance at the country park. This was especially true at a corridor that extends from the fish pond south-west to the Folders Lane East. This was where we focused our searching, which turned out eventually to be the right idea. At 10.30 the sunshine finally made a prolonged appearance and the wind died down slightly. This appeared to trigger the daily emergence of the hairstreaks to warm up on the bracken. The first one we found was perched at quite a gradient on one of the fronds, perfectly angled towards the sun. After a few minutes of sitting very still, it switched sides rather in the fashion of a sunbather aiming for an even tan. As it had not yet gained enough thermal energy it was being quite ‘co-operative’, allowing for great views. This sighting was repeated with up to three other Black Hairstreaks, a very satisfying way to see a new butterfly species for me: not a common occurrence!

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Although the sexes are hard to differentiate on physical appearance, it is likely that those we found were females. The males will emerge earlier, in order to have established a territory prior to the emergence of the females. They will fiercely defend their territory, which is usually centred around an oak known as the ‘master oak’, and approaching the end of the flight period this activity will render them quite battered and damaged. It is likely that this species is past its peak already this year. The species’ very short flight period is one reason why this colony may have remained undiscovered for such a long period of time. Years where the population is dramatically increased compared to previous and following years are also characteristic of this species. It is likely that this year is one of these ‘boom years’ which is what may have lead to this year being the one in which this colony was finally discovered. So if you haven’t yet had a chance to visit this true Sussex rarity, I would recommend that you do so sooner rather than later. Their short adult stage will be over before the end of June, and in future years there probably won’t be as many as there have been this year.

Black Hairstreaks are not the only entomological rarity I’ve had the good luck to see in Sussex this month. At the beginning of the month I took a walk along a small stretch of the River Rother, near Fittleworth in West Sussex. Having been advised about their presence there by Amy Robjohns and Olly Frampton, I was on the lookout for Common Clubtails, a species that isn’t actually as common in the UK as its name suggests. On the British Dragonfly Society website it is described as “extremely local”, only being found on a few rivers in Wales and southern and central England.

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However, its scarcity on a national basis was certainly not evident along this tranquil, luscious river in the mid-morning sun. Along only a few hundred metres of the river we managed to find at least 10 either hunting along the river or perched on bankside vegetation and overhanging willows. The vast majority were males which were patrolling their recently acquired territories while many females would be seeking protection in the nearby woodlands away from the water. They will soon return to mate and lay a new batch of eggs, which will complete their immature stages in the silty riverbed within 3-5 years.

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The invasion continues

This winter Europe has been host to an avian phenomenon I wasn’t even aware was possible. Hawfinches in the UK are very rare and elusive birds, mainly confined to large areas of forest such as the Forest of Dean and the New Forest. Indeed, in February 2017 I hitched a lift with Josie Hewitt for a two hour journey to the New Forest especially to see these birds, and it’s funny to think how oblivious I was to the fact that it would become clear by the end of the year that it was an unnecessary trip.

I don’t think anyone is quite sure why, but this winter Hawfinches have truly irrupted from their core European breeding grounds. The areas where these usually strictly forest-dwelling birds have been recorded over the past few months is incredible, including the Moroccan Sahara, Kuwait and Alaska! In Sussex, where hardly any are seen outside of West Dean Woods, flocks have surpassed 100 individuals at locations scattered across the county. I am not aware of any previous such invasions of this species, so it definitely feels like a once-in-a-lifetime experience.

Last weekend, I was ringing at fellow trainees Dave and Penny Green’s garden near Wisborough Green. I had heard that there were one or two Hawfinches visiting their large Yew tree, so I was fairly hopeful that some brief sightings would enliven our ringing session a little more. However, it soon became clear that my expectations were far too low! We were treated to an almost constant presence of Hawfinches throughout the day, at least 6 I think and possibly up to 10 were visiting the Yew at one point. This allowed for some absolutely brilliant views of this normally tricky-to-see species.

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Beautiful male Hawfinch

As you can see from the photo, Hawfinches have a massive bill. These have evolved to crack really hard nuts and seeds, such as cherry stones which they can easily crack. They certainly are attractive, chunky finches and I do hope that the invasion continues, and perhaps there’ll be a bumper breeding season for them here in the UK!

Pectoral Sandpiper

Last Sunday afternoon I sat in the West Mead hide at Pulborough Brooks, with my binoculars focused on the far right corner of the pool directly in front of me. Among the Lapwings and the Teal was the silhouette of a Pectoral Sandpiper in terrible back-lighting.

There was no mistaking that this was a bird I was very pleased to see. One challenge of mine for this year is to get to 200 bird species for BBC Wildlife Magazine’s #my200birdyear, and this was my 193rd. Furthermore, Pulborough Brooks is exactly where I saw my first and only previous Pectoral Sandpiper, over 3 years ago. On that day in 2014 the Pectoral Sandpiper was so distant I didn’t even attempt a photograph, however this time this one was unusually close.

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The lighting was really poor, but at least I attempted a photo unlike my previous sighting three years ago!

Pectoral Sandpipers breed in North America and Eastern Siberia, yet despite the great distance from their breeding grounds they are still the most common Nearctic wader to reach our shores each year, mainly during autumn. Sussex definitely seems to attract its fair share, and in my experience Pulborough Brooks seems to be the best site in Sussex for them at the moment. There may have been at least three at this wetland site this autumn, which is an amazing total for a bird that would have had to cross the Atlantic or the whole of Siberia and Europe to reach here.

I have about a month and a half to find seven more species to make 200 for the year. It is possible, although it will be difficult. There are quite a number of species I’m yet to see, but it will all rely on how lucky I am!

Slime Moulds: Fascinating and Complicated

It is without a doubt that the vernacular name ‘slime mould’ is not the most appealing, although the slime moulds themselves are often not the most appealing organisms to look at either. However, what they may lack in aesthetics they do make up for in pure ‘bizarreness’.

Taxonomy is the science of classifying living things into groups such as phyla, families and genera. And slime moulds, scientifically known as Myxomycetes (or ‘myxos’ for short), are a taxonomist’s worst nightmare. Their taxonomy is so poorly understood that even which kingdom they should be classified under is unclear. Some still class them as fungi, however others think they’re protists.

The reason why I find them so interesting is their behaviour when food is not plentiful. When there is a decent availability of nutrients, they will live single-celled lives; yet whenever food becomes hard to come by they will congregate together. Once they are in this state they will become able to detect food sources. When they congregate, they become noticeable, as they produce fruit bodies which release spores much like fungi. This helps these fascinating moulds to colonise new areas.

Yesterday, the last day of September, I was at a Sussex Fungus Group foray at Tilgate Park in Crawley. The diversity of fungi found was incredible, and we also came across this slime mould. It was identified as Stemonitopsis typhina, and what you can see in the photo are the immature fruit bodies. Given a short while, these fruit bodies will mature and release spores.

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However, not all slime moulds produce fruit bodies like this. Slime moulds can reproduce using gametes, asexually or a mixture of both. Far too complicated for me to understand at the moment! Perhaps as complicated as the fern reproduction I explained in a previous blog post. I think that there’s a lot still to learn about slime moulds.

 

Flower of the Illyrians

Yesterday, 2nd September, was the final field meeting of the year for the Sussex Botanical Recording Society at Chailey Common. Chailey Common is a good example of where conservation grazing has been put into place, in order to keep dominant vegetation to a level that won’t swamp more precious flora. Sheep, ponies and cattle are rotated around the commons in order to control plants such as birch, gorse and bramble that will degrade the quality of the heathland habitat if they get out of control.

It was great to see how this conservation grazing was working. It allows smaller and more fragile wildflowers to grow as well as others that may have been at risk from habitat loss. We recorded a good number of scarce and interesting plants, including Heath Milkwort, Scented Agrimony and Lesser Skullcap.

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Scented Agrimony, with subtly notched petals distinctive of this species.

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A flower of Heath Milkwort, so-called as farmers thought that allowing their cattle to feed on this plant would increase milk yields.

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The minuscule flower of Lesser Skullcap.

However there was one stand-out highlight, and that was a small patch of Marsh Gentians. Gentians are often a favourite of photographers as they have a photogenic beauty. I am not a photographer, but I did try my best with the following shots.

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The Marsh Gentian is quite a locally distributed plant, growing on wet heathlands rather than marshes. It does benefit from grazing, which is perhaps why some of its main strongholds are places like the New Forest and Ashdown Forest.

It is one of a number of Gentian species in the UK, in the genus Gentiana, including Autumn Gentian and Field Gentian. On a global scale it is cosmopolitan, with around 400 species; and some species are known to have been used in herbal medicines for quite a variety of ailments. These range from cancer to malaria to parasitic worms, however studies have been conducted that don’t prove that it has any benefits beyond a placebo effect! Despite this, the genus name Gentiana is in honour of the Illyrian king Gentius, who supposedly discovered the plant’s tonic qualities. What it is definitely known to be good for however, is as a dye, especially the Marsh Gentian.

 

Marsh Gentian is my 500th British plant and although summer is now over and most flowering plants are past their peak, there are still late summer and autumn species in bloom. Some of these I hope to see over the next few weeks!

 

 

 

Amphibian lifer!

As many of you will know, I’ve been working hard on my pan-species list recently. It’s a list of all the species I’ve seen in the UK and I’ve just broken the 2200 species mark. With an ambition to get to 3000 by mid-August 2018, 13.5 months away, I need to use every opportunity I can get to boost my total! Mostly these days my lifers are invertebrates with some plants, mainly beetles and bugs. Very rarely do I get a vertebrate lifer and I certainly wasn’t expecting to get an amphibian lifer any time soon! However, last weekend I visited Warnham LNR, a fantastic little wildlife site right on the edge of the large town of Crawley.

I have visited this beautiful local reserve only once before, yet then I had no idea about the population of a rare British vertebrate that inhabits the small ponds and the main lake of the reserve. Of course the reserve always holds plenty of wildlife and therefore my first visit was excellent, yet my recent visit was made all the more special by this exciting creature.

With a distinctive call that has earned this species its alternative name of laughing frog, the Marsh Frog Pelophylax ridibundus has been a main attraction at the reserve this spring/early summer although I only found out about it not long ago. With my amphibian & reptile total relatively low on my pan-species list, a new addition in either group was greatly needed and wanted and therefore I was eager to visit and hopefully catch a glimpse of this generally shy species if I was lucky.

My expectations were that I would possibly hear the plop of a frog jumping into the water unseen, or catch a swift movement of a frog fleeing out of the corner of my eye. However, these expectations were soon proven very wrong. It is a non-native species only introduced into the UK in 1935 in Walland Marsh, Kent and has since spread to areas in East Sussex and London. The population at Warnham LNR must be one of the only places where this species is found in West Sussex. The purpose of its introduction was to occupy an ecological niche as it is more aquatic in nature than the native Common Frog and more frequently breeds in ditches and dykes. Many of the places Marsh Frogs inhabit aren’t busy, such as the East Sussex levels, which I suppose has lead to its tendency to leap into the water at the slightest human disturbance. But the Warnham Marsh Frogs behaved in a way completely opposite and, probably due to the large numbers of visitors, were not too afraid of humans at all! Throughout the visit I must have seen at least 10 of varying colours, patterns and sizes. Not a bad looking species whatsoever!

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There’s a fungus on the Town Hall Clock!

If you’ve read my latest post you would know that I am a regular participant of #wildflowerhour. During last week’s Wildflower Hour there were predictably more photos due to the increase in flowering plants as spring progresses. Among these flowering plants was the easy-to-overlook Moschatel (Adoxa moschatellina), which I had never recorded before.

So last week I set out with a picture of Moschatel in my mind so that if I did come across the species I would recognise it. Yesterday I visited Pulborough Brooks RSPB reserve in West Sussex and I did both of those things: I came across a couple of large patches and I recognised it!

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The flower head. You can see that it is cube-shaped, which is what lead to the alternative vernacular name of ‘Town Hall Clock’.

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The whole plant

As you can see from the above photographs, Moschatel is not a hard plant to miss. Its flower heads are only slightly lighter than the leaves and therefore not easy to spot when they are lined up against the foliage of a woodland floor. To be honest, I was quite pleased with myself for managing to spot this indistinctive plant!

However once I had a closer look, there was more to see. One particular patch was very heavily infected with what appeared to be the fungus Puccinia albescens, which covered the leaves, stem and flowers of several plants. This species is a rust fungus, which is a type of fungus that usually parasitises wildflowers and other small plants. There is an incredible diversity of host plants within the 7000 species of rust fungi as most plants are only infected by a single species.

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The close-up photograph above shows the pustules of the rust fungus, which is just one part of the complex life-cycle of rust fungi. These pustules erupt at this time of year and produce uredospores which are carried on the wind to new plants of the same species to infect.

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Telia

Also present alongside these pustules are what I believe to be the telia of the same species. These telia – the dark, round spots – are produced in the autumn in most species and would have overwintered. The telia produce teliospores, which are another method the fungus uses to spread as they disperse to find more plants of the same species to infect, just as the uredospores do.

The life-cycle of rust fungi is very complex and here I have explained it only briefly – different species of rust fungi can have different life-cycles and some infect two completely unrelated species during their life-cycle. These multi-host fungi are known as heteroecious fungi and one host plant is infected by the uredospores and the other is infected by teliospores. As Puccinia albescens is not heteroecious (and is autoecious), its life-cycle can be completed on just a single host species – Moschatel – and the single host species is infected by both the uredospores and the teliospores. Some good websites to visit for more information on the life-cycle of rust fungi are:

http://www.biologydiscussion.com/fungi/life-cycle-and-the-spore-stage-of-rust-fungi-fungi/64083

http://website.nbm-mnb.ca/mycologywebpages/NaturalHistoryOfFungi/Pucciniales.html – this one includes a lot of information, however it also contains a lot of scientific jargon and complicated vocabulary.