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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Orchid on the Hill

The Early Spider-orchids Ophrys sphegodes at Castle Hill NNR have one of the best views of the South Downs as well as Brighton to their south-west. On the northern edge of Woodingdean, a chalk grassland slope supports this nationally scarce species, which has only a scattered distribution along the South Coast from Dorset to Kent.

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This orchid is named after its appearance, with its flowers apparently resembling the abdomen of orb-weaver spiders. However, its flower shape has evolved so that it resembles bees, which come to try and mate with the flower, known as pseudo-copulation. This is also the case in the perhaps more appropriately named Bee Orchid for example. To complement the shape of the flower, these orchids also release the scent of female bees which further entices the male bees to unknowingly pollinate the plants.

However this technique may show to be detrimental towards the success of the species in the face of climate change. Despite the strength and accuracy of the scents wafted by the flower, they cannot compete with actual female bees. Therefore, the plants most likely to pollinate and reproduce successfully are those which blossom after the male bee has emerged although before the females. Although sadly warmer spring temperatures are pushing the phenology (life cycles) of these two species out of sync.

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It is also interesting to observe the variation in the exquisite patterns shown on different individual flowers, such as these:

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Travelling to find these orchids (a new plant for me) was a perfect break from revision. Despite their rarity, there are several reliable sites such as Durlston Country Park and Dancing Ledge in Dorset, Samphire Hoe in Kent and of course where I visited today, Castle Hill NNR in East Sussex. I would definitely recommend looking for them before they stop flowering in early June!

 

The Conservationist’s Battleground

It’s just past midday and in the 35 degree heat, we drive along the National Highway-29 with an expanse of wild floodplain to our north and forested highlands to our south. As we pass a small, one-man roadside fortification, a shooting post, we are told about this area’s ever-present war. This is not just a deterrent where untrained local militia shoot at an intruder’s feet to ward them off. Someone was fatally shot here the previous night, as they are every few weeks.

‘The Pride of Assam’ roams the Kaziranga National Park we had just exited. With an alleged higher potency than the horns of its African counterpart, it is in particularly high demand in Asian countries, especially Vietnam, where it is used as a supposed cure for cancer. Its value is highlighted by the risks the poachers will take to harvest it. Approximately the same number of people are killed by the anti-poaching force each year as their quarry are by poachers: the Greater One-horned Rhinoceros.

The Greater One-horned Rhinoceros, also known as the Indian Rhinoceros, is one of five rhino species worldwide, with three being found in Asia. Every species has experienced declines.

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Adult female Greater One-horned Rhinoceros in Kaziranga National Park

The Javan Rhinoceros is one of the rarest large mammals in the world. It used to be widespread in south-east Asia, with its range stretching from the Sunderbans in east India, east to the Vietnam coast and south to Central Java. Now, only around 120 years  since it first became locally extinct in India, the sole remaining population inhabits the Ujung Kulon National Park. The park has an area of 1200 square kilometres, of which about a third is marine and supports as few as 60 Javan Rhinos.

The Sumatran Rhinoceros is only slightly less rare. It once had a similar range to the Javan Rhinoceros, and although it didn’t inhabit Vietnam, it was found in Borneo, where one of the four or five populations is located. Although there are more individual populations than the Javan Rhinoceros, these are tiny and probably add up to fewer than 100 individuals.

Fortunately, the Greater One-horned Rhinoceros is approaching 4000 individuals having almost doubled over the past couple of decades. Despite this, as with the other two species we have looked at, the distribution has decreased from a wide band ranging from Pakistan to the easternmost point of India to several scattered pockets in south Nepal, West Bengal and along the Brahmaputra River in Assam; and there is a chance there is a population in the Royal Manas National Park in Bhutan.

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One of the first rhinos we saw in Kaziranga National Park

The increase in the population of this species is at least partly due to the work of anti-poachers around the populations of this rhino, particularly around the national parks where many of the rhinos live. Nepal is an excellent example where the holy grail of zero-poaching has actually been achieved, where several very popular species in the markets of Vietnam and other East Asian countries such as Tiger, Asian Elephant and Rhinos live. With almost a quarter of the country assigned as national parks and other protected areas such as Bardiya NP and Chitwan NP, where I was lucky enough to see both Tiger and Rhino several years ago, and a huge commitment from the authorities, it has illustrated that the war against poaching doesn’t have to be an insurmountable battle.

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Inhabitants of the many river sandbanks along the Brahmaputra River. In some places such as near Chitwan National Park, children are being educated about conservation with projects such as Eco Clubs in schools.

In my opinion Kaziranga National Park and other areas in India which support the Greater One-horned Rhino may soon realise the abolition of poaching. If the anti-poaching rangers continue risking their lives to save this magnificent animal, and other approaches such as monitoring and education continue to be implemented, then this rhino may just survive and perhaps even prosper.

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Mother and calf on the misty plains of elephant-grass.

 

 

Thick-headed

At the end of March I had the good fortune to be able to visit North-east India for a few weeks. For the first part of our trip, we stayed at the Sunderban Jungle Camp on the edge of the Indian Sunderban Tiger Reserve. Each day we would take a boat and explore the unique habitat of the mangroves and hope to find some of the special species that inhabit it.

Luckily we had several great sightings of restricted-range birds in particular, such as Brown-winged Kingfisher. This species is restricted to the mangroves on the coast of the Bay of Bengal and the Andaman Sea from Odisha to the southern tip of Myanmar. It was one of six Kingfisher species encountered in the Sunderbans, surely the Kingfisher capital of the Indian subcontinent.

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Brown-winged Kingfisher

Although my personal highlight was not the intricate beauty and variety of the many kingfishers seen, but the drab Grey Thickhead. Unsurprisingly this is not the modern accepted vernacular name for this species, although it is the literal translation of the Mangrove Whistler’s scientific name, Pachycephala cinerea. Although is is unclear to me what warranted their scientific name, the genus appears to me to be just like typical flycatchers albeit with a slightly broader bill and perhaps chunkier. However it is not the appearance that drew me to this species, but the melodic song.

The voice of the Mangrove Whistler rises high and proud above the accompanying chorus of the mangroves. It consists of a series of tuneful notes which crescendo to a concluding flourish which is audible even above the din of the motorboat as it chugs along down the wide mangrove channels.

Having heard the distinctive tune, our guide Sujan ordered our boat to be stopped at the edge of the mangroves near where the whistler was whistling. To him it sounded abnormally close, the species usually prefers to remain deep within the mangrove forest without access by boat. This is why they are very tricky to see in the Sunderbans: walking is forbidden due to the danger of tigers. So when I caught a movement out of the corner of my eye, I knew that I was very privileged.

The small nondescript bird flew up to a convenient perch on one of the higher mangrove bushes along the river. From there it began to sing, occasionally switching position but almost constantly in view for several minutes. So hard to find, so unexpected that this species wasn’t even on our trip checklist – a cumulative list from around 9 years of running this trip with 2 or 3 trips a year. Our guide has the honour of having seen over 1100 species of birds in India, yet the elusive thickhead only 5 or 6 times before.

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The Mangrove Whistler sitting dignified on its mangrove perch

Mid-March Moth Madness

After a snowy delay, last weekend it seemed like spring had finally sprung and temperatures rose into double figures. Looking at the forecast for this weekend and into next week however, it looks like the wintry weather will return once again which is very odd for this time of year. I’m usually a fan of a bit of snow, but only at the appropriate times of year. So I decided to write this blog post to try and keep my spring feeling going for as long as possible, before the snow showers begin to move in from the east again.

Saturday night was the first time I have put my moth trap out this year. In previous years I have been a little more keen, with very little reward and sometimes even null counts at this early stage in spring, so I decided to hold it off until now. And with the Beast from the East only about a week gone, my hopes were not particularly high. Although I was in for a surprise.

Most of the time, I just leave my trap out for the whole night and check it in the morning. However, on the off-chance of something notable (or anything at all!) being in there, I decided to look down from my bedroom window just an hour or so after switching on the light. To my surprise I saw what seemed to be an Oak Beauty already within the trap, so I rushed down to check if there was much else about.

To my immense surprise, there were at least 20 moths flying around the trap and on the nearby house wall. Most were March Moths as well as several more Oak Beauties, along with a couple of Tortricodes alternella and a Common Quaker. Already we had recorded around twice as many moths as I usually get in an early-spring night!

I was more than keen to check the trap the following morning. Unsurprisingly, there were moths everywhere, with the final tally being 55! I would be happy with that in May or September, let alone the first half of March! I will run through a few of the stand out highlights:

Small Brindled Beauty

This was the rarest moth that I caught last night, and the second time I’ve caught this species, the previous occasion being early March last year. It is most common in southern England, becoming rarer further north although classified as ‘local’ – found in less than 300 sites nationally. The females of this species are one of many winter and spring species that are apterous – lacking wings. The females of many of these apterous species seem completely unlike most moths to me, although I’m yet to find one myself.

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Small Brindled Beauty

Dotted Border

This species is unique among the early spring moths as it is one of the few Geometrid moths out at this time of year. In my experience it is usually the Noctuids (such as the Clouded Drabs, Hebrew Characters and the Quaker species) that are the most commonly trapped, although the most abundant species caught during this night were the 18 Oak Beauties which is a slightly unusual Geometrid species. The Geometrids can be distinguished by the way they hold their wings; most Geometrids hold their wings out to the side whereas most Noctuids fold their wings over their abdomen.

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Dotted Border

This species can usually be identified by the row of dots running along the bottom of the wing which you can see in the photo above. However, it is a variable species throughout its distribution and there are forms which are very dark making the row of dots (the dotted border) very hard to see.

Clouded Drab

This species is quite common especially where its foodplant Oak is plentiful although, despite its name, it is can be really nicely patterned. It is another species that is really variable, with many colour forms. We caught three, one of them in particularly was particularly good-looking, with its pattern enhanced by the flash on my camera.

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Clouded Drab

Hopefully the upcoming cold snap will be the last of the winter, and spring will be allowed to continue unabated. I look forward to moth trapping further once it warms up again, hopefully we’ll continue with some good numbers!

Final Tally

  • Common Quaker 3
  • March Moth 9
  • Oak Beauty 18
  • Hebrew Character 4
  • Tortricodes alternella 2
  • Small Brindled Beauty 1
  • Dotted Border 5
  • Clouded Drab 3
  • Small Quaker 8
  • Chestnut 1
  • Brindled Pug 1

 

Eastbourne Strikes Twice

This morning, after struggling through incredibly thick mud, I reached a huddle of birders all looking at a small Robin-sized bird with a faint blue crescent on its breast feeding on the edge of a large reedbed. It was a male Bluethroat, a fantastic record for the time of year and for Sussex.

The bird was first seen last Sunday at West Rise Marsh in Eastbourne and identified from photos on Tuesday. Luckily it stayed around and has since allowed many Sussex and national birders to see it although it has been elusive. Unusually for me, it was not as elusive when I went to see it as I immediately had it in my binocular view after arriving. Much better than standing around for hours in the biting wind which some birders have had to do over the past week!

It appears to be a White-spotted Bluethroat, one of two subspecies of Bluethroat that have been recorded in the UK. It seems to be the less frequent subspecies, with the Red-spotted Bluethroat being the other that sometimes reaches our shores. Due to the difference in latitude of the two subspecies’ breeding ground, they typically arrive at different times of year. The White-spotted is most commonly found in late March and April whereas the Red-spotted is more likely to be found in May. Although White-spotted is the earlier arriver, it is more likely that this bird has been wintering in the UK, rather than having overshot its breeding grounds on its spring migration.

Occasions of Bluethroats wintering in the UK are occasionally recorded, for example last year a bird was found in February in Lincolnshire which remained until the end of March. Presumably it then attempted to migrate to where it thinks its breeding grounds are. It will be interesting to see if this Eastbourne bird stays much longer and whether it tries to set up a territory here or flies elsewhere to breed.

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Fantastically, this is not the first Sussex rarity that Eastbourne has had to offer this winter. Black Guillemots, although they breed on remote islands in the north of England, are even rarer in Sussex than Bluethroats, so for one to turn up in Eastbourne’s Sovereign Harbour was quite special. It has been present since late November, although I waited until the New Year before going along to see it. It’s a wonderfully confiding bird in a great setting!

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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!