Skulker

As many of you will know, I am a trainee bird ringer and have been since 2014. Involved in the complicated process is putting a small, lightweight ring on the leg of a bird, on which is inscribed a unique number. This enables individual birds to be recognised if they are later recaught or found dead, allowing ornithologists to learn more about their migration and biology.

In my four years of being a ringer, I’ve had the chance to ring a wide variety of bird species, ranging from over 100 Blue Tits to some scarcities including Yellow Wagtail, Redstart, Wheatear and Wood Warbler and larger birds such as Stock Dove and Woodpigeon. However, last Sunday’s ringing experience will probably go down as one of my favourites so far.

Fellow Sussex young birder Mya Bambrick and I arrived at Knepp Estate, south-west of Horsham, at 6am. There we met my trainer Tony Davis who had already set up four mist-nets around a field consisting of mainly bramble and willow scrub. This is a fantastic habitat for migrating birds as well as several scarce breeders due to the amount of cover the scrub produces and the blackberries which ripen at exactly the right time to fuel many migratory passerines on their southward journeys. The mist-nests are ideal for catching birds as they are fine enough to be invisible to birds flying between bushes, which fly into the net and fall into a pocket from which they are extracted by licensed ringers.

It was on the first net-round when I noticed that there was something slightly different in the bottom pocket of one of the mist-nets. It didn’t take long for me to realise that it was a Grasshopper Warbler. Grasshopper Warblers, so-called due to their bizarre song which resembles that of a stridulating grasshopper, is a localised breeding species found mainly in fens and coarse grassland and is not often found in high density. However, while researching for this blog post, it was good to learn that they are showing a positive population trend with the UK population experiencing a 23% increase in numbers in the 14 years between 1995 and 2009. This is thought to be as a result of improved survival rates in the wintering grounds of west Africa. Particular preference is shown by British Grasshopper Warblers towards Senegal and The Gambia, which we have learnt from recoveries of ringed birds in those countries. However despite this recent increase, this is in comparison to a proportionally larger decrease which took place in the years prior to that period. Only a few decades ago, this species used to be found in a greater range of habitats than to which it is currently restricted.

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The Grasshopper Warbler

Grasshopper Warblers (often shortened to just Gropper) are renowned for the difficulty involved to see them. They have skulking habits, only really coming out into the open when the males sing their distinctive song. Most of the time they remain hidden in thick vegetation. In fact I’ve only seen this species twice before, and both times the birds were located by the loud song. The first time was a bird claiming its territory in May 2014 in a sand dune in Budle Bay, Northumberland and the second had probably only just arrived in the UK in April last year, when I found one singing in a garden at Selsey Bill in West Sussex from a small clump of ornamental pampas grass. In fact in the past 20 years Tony had only caught two or three, highlighting how lucky we were to catch this reclusive skulker.

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This was my only photo of a Grasshopper Warbler before Sunday, from Northumberland. This photo illustrates how hard-to-see Grasshopper Warblers are usually. And this one was, in relation to most other sightings, ‘showing well’!

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Species no. 3000!

Admittedly Stratiotes aloides, known vernacularly as Water-soldier, is not the most desired plant to have in an ecosystem. It is possible that it is native in East Anglia and Lincolnshire however in Sussex, where this species became number 3000 on my pan-species list, it is more likely to be introduced.

Yesterday I joined the Sussex Botanical Recording Society on a visit to Court Lodge Farm on the Pevensey Levels, which possesses a rich assemblage of aquatic plants in the many ditches. Some special species recorded included Potamogeton obtusifolius (Blunt-leaved Pondweed) and Petroselinum segetum (Corn Parsley), the latter growing on the banks of the ditches rather than within them as was the case with the pondweed.

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An example of one of the ditches where we were recording. The majority of the water plants you can see in the photo would  be Lemna trisulca (Ivy-leaved Duckweed), Elodea nuttallii (Nuttall’s Waterweed) and the aforementioned Potamogeton obtusifolius (Blunt-leaved Pondweed).

Although despite these Levels specialities being present, for the ditches it is hard to escape the colonisation of several non-native invasive plants. Fortunately we didn’t come across any ditches which were dominated by these unwanted waterweeds however both Azolla filiculoides (Water Fern) and Hydrocotyle ranunculoides (Floating Pennywort) were found along with the robust growth of Water-soldier.

Water-soldier can be quite problematic for native flora. Small populations can, if left undisturbed by boats or large numbers of waterfowl, develop into armies. These can completely annex stretches of canals or ditches, out-competing ‘friendlier’ water plants for resources. The following quote is from the Water-soldier’s species account in the recently published Flora of Sussex: “On Pevensey Levels it has spread considerably, and in 2010 was found to be completely covering a ditch for several hundred metres”.

Despite this, I find its biology quite interesting. In the autumn it will begin to stop photosynthesising, and gradually lose the gas in its leaves that keeps it afloat. It will sink to the bottom of the ditch or canal where the water is unlikely to freeze. In the spring the increased strength of the sun’s rays will penetrate deep enough to allow the sharp, serrated, sword-shaped leaves to photosynthesise again, producing oxygen which gives the rosettes their buoyancy.

I was not originally planning to write a blog post on the Water-soldier until I realised today while inputting yesterday’s finds into my list that it fits into the 3000th slot. I am quite relieved that I have managed to reach this milestone, as the target I set myself in a blog post I wrote when I reached 2000 was to record my 3000th species before my 15th birthday. As of today I’m 14 years, 11 months and 1 day old. So I reached my target, but only just. It is hard for me to imagine stopping pan-species listing, however with upcoming GCSEs and A Levels I imagine I might have to slow down a little. But to keep it ticking, I have decided to set myself another target: 4000 by the end of 2019. Wish me luck!

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Two plants surrounded by Frogbit (Hydrocharis morsus-ranae) resembling miniature water-lilies.

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The snow-white flower of Water-soldier. The flowers are not seen too often, with the main method of reproduction being vegetative: the lowest leaves of the plant have axillary buds which will detach when the leaves decay and can disperse long distances before resprouting. This species is what’s known as dioecious – this means that male and female flowers are found on different plants. For some reason, there are very few if any male plants in England, so all reproduction in this country is vegetative as described above.

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The four or five plants in the photo here represent about half of the largest population of them I saw, luckily it hasn’t reached the levels of dominance seen at other parts of the Levels.

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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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.

 

The Wild Wolves of Sussex

Last weekend, 1-2 July, I was fortunate enough to be attending a two-day bee workshop led by pollinator expert Steven Falk at the Rye Harbour Nature Reserve near Rye in East Sussex. Throughout the weekend we were blessed by an incredible diversity of solitary and social bee species alike, with around 50 species of the Apoidea being found during the weekend.

However, one species that caught my eye wasn’t in fact a bee. Covering the sandy paths at some points were a multitude of wolves, excavating burrows and looking for their next meal. They prowled along the tracks and up the sandy slopes, concentrating their efforts on the path-side bramble bushes. This is where their prey is most often found feeding, unaware of the wolves sneaking up behind them until they latch on with a relentless bear-hug.

Of course, the wolves I’m talking about aren’t the canids that roam remote areas of Eurasia and North America. Just as fierce, however slightly smaller, are Bee Wolves, Philanthus triangulum. Bee Wolves are the largest solitary wasp in Britain and they need to be in order to tackle their favoured prey: honey bees.

Bee Wolves used to be not only the largest but also the rarest solitary wasp in Britain. However, since a couple of decades ago, their population has been on the increase and they’ve spread to a number of new sites. Their numbers are not as large now as they were a few years ago, however there are still more about than there were 25 years ago. It’s great that these fascinating insects are more widespread now as they’re incredible to watch.

They weren’t too scared of humans at all, in fact we were able to watch with such proximity that on a couple of occasions one actually landed on Chris Glanfield’s phone while he was trying to take a photo!

Being solitary wasps, they each dig their own long burrow. These burrows contain many small chambers, as many as 30, each containing several bees. In each chamber an egg is laid, and when it hatches the larva feeds upon the bees inside the chamber before emerging as an adult Bee Wolf. The bees are not dead but paralyzed as it helps them to keep fresh and juicy for the developing larva.

We were lucky to be able to watch several wasps excavating and entering their burrows as well as carrying their prey around. This was the first time I had ever seen a bee wolf and I’m hoping I get another opportunity to watch them before too long!

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An adult Bee Wolf on the path

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a Bee Wolf outside a burrow it has only just started to excavate

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A Bee Wolf proudly outside an unfinished burrow I watched her excavate in only about 10 minutes!

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Adult Bee Wolf

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Bee Wolf

 

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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Summer migrant at last!

The weather last weekend certainly suggested that spring had sprung and the many signs of the changing seasons about such as flowering Wood-Sorrel and active Bee-Flies supported that fact. However despite the beautiful sunny weather, by yesterday morning I was still yet to see a summer migrant this year!

Early yesterday morning I spent over an hour at the beautifully serene and calm Hedgecourt Lake waiting for a particular species I was hoping to see arrive. Ospreys are apparently seen here every spring and autumn when they travel through on their way to their more northerly breeding grounds. However I have never seen a single one here.

The previous evening (Saturday) not one but two Ospreys were reported nearby at Weir Wood Reservoir just as the sun was setting at 18:30. I was hoping that they would carry on their migration northwards earlier this morning and arrive at Hedgecourt, which is the nearest large waterbody to the reservoir. That is the main reason why I was up nearly at dawn getting ready to wait for one to appear.

Unfortunately I didn’t have any luck with the Ospreys at Hedgecourt although there were some other nice birds about around the lake, with many singing Chiffchaffs, a displaying Sparrowhawk and a male Mandarin which flew in.

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Upon arrival back home I heard news that a couple of nice summer migrants had been seen at Weir Wood Reservoir while I had been at Hedgecourt. These were an Osprey, possibly one of the two there yesterday, and a Little Ringed Plover. Encouraged by this news we decided to head to Weir Wood Reservoir to see if we could see either of these birds ourselves.

Weir Wood Reservoir is quite a large reservoir and the whole reservoir cannot be seen from just one viewpoint. Therefore most people visit both ends of the reservoir, the West end and the Dam end. The West end was where we visited first and where the Ospreys were seen yesterday evening and this morning.

Despite the large number of birders at the car park there were few interesting birds to be seen and certainly no Ospreys. According to one of the birders there, Alastair Gray, they can remain well-hidden during a lot of the day simply perched in the trees beside the reservoir and only become noticeable when they set out to fish most commonly in the early morning and late afternoon. They don’t like to fly a lot unnecessarily as it really upsets the local crows which harass the Ospreys until they land! However there was an immature male Goldeneye amongst a group of Great Crested Grebes which was my first of the year.

After searching for hidden Ospreys unsuccessfully we then moved on to the dam end to look for the Little Ringed Plover. The walk up to the dam wall was alive with the song of many Chiffchaffs and the blossoming Blackthorns were full of life. There were a pair of Pied Wagtails on the grassy bank of the dam and a Grey Heron flew overhead.

After walking along the dam wall for a little while to my relief the Little Ringed Plover came into view. It was small and slender, moreso than its relative the Ringed Plover, and was feeding right on the water’s edge. I was able to get quite close, up to a distance of about 10 feet, and from there I was easily able to observe its distinguishing features. To separate Little Ringed from Ringed Plover, the easiest feature to see is the colour of the bill. Little Ringed Plovers have an entirely dark bill whereas Ringed Plovers have a bill with an orange base and a dark tip. Also,  if you are close enough, you might be able to see the yellow eye ring of a Little Ringed Plover which is a feature absent in Ringed Plovers.

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The Little Ringed Plover

Although Little Ringed Plovers are regular breeders in England and Wales in the modern day, they first bred as recently as 1938. Their expansion across southern Britain is partly due to the creation of man-made habitats perfect for breeding such as water-filled gravel pits. Now over a thousand pairs of these small waders arrive here each spring to leave again in late June/July.

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I am pleased that I have now managed to find my first ‘proper’ summer migrant of 2017. Over the coming weeks, migration is set to pick up as winds become favourable and it becomes warmer. Hopefully I will soon be waking up to the song of Blackcaps and Willow Warblers!