Myrmecomorphy in action!

Sunday the 15th October was the date of the Amateur Entomologists’ Society field meeting at Rye Harbour Sussex Wildlife Trust reserve. It’s not often that I do a focused invertebrate hunt at this time of year, so I was looking forward to seeing what we found.

The field meeting was unexpectedly good on the arachnid side of things. I had no idea that the reserve was so rich in numbers and species of spider. We spent most of our time in a compartment of saltmarsh and shingle, where the shingle was really shallow. The layer of shingle was about two stones thick, and the soil beneath it was compact. This meant that the spiders could not escape deeper into the shingle as they would at most shingle sites.

One of the highlights of the field meeting spider-wise was the fantastic Myrmarachne formicaria. As the scientific name suggests, this species of spider is an ant-mimic (the prefix ‘myrm’ means ‘ant’ and a formicarium is an ant farm). The mimicry of ants in the animal kingdom is known as ‘myrmecomorphy’ and is quite common across a number of invertebrate orders. Invertebrates that are known to be ant mimics include young grasshoppers, true bugs (Hemiptera), flies, beetles and of course spiders.

But why do so many invertebrates mimic ants? Ants are known among the predators of invertebrates to be aggressive or distasteful, so they are avoided. And the predators will also avoid any insects that look like them, but lack any means of defence such as the young grasshoppers. This is known as Batesian mimicry, as it was first described by H W Bates. Some ant mimics have even gone as far as to mimic the ants chemically as well, by emitting ant-like pheromones, which is referred to as Wasmannian mimicry.

However, Myrmarachne formicaria may mimic ants for a different reason. It is thought that some spiders mimic ants not only for protection against predators but also so that they can hunt the ants themselves. Ants will overlook the spiders as one of their own colony, giving the spider the perfect opportunity for a meal. This type of mimicry is aggressive mimicry. As you can see from the photo below, the spider has a long abdomen, which helps it to resemble an ant.

Myrmarachne formicaria male by Evan Jones

Myrmarachne formicaria, photo by Evan Jones, one of the field meeting attendees.

Myrmarachne formicaria really was a fantastic sight, and I hadn’t personally seen anything like it before. It was fascinating to learn how and why so many different invertebrates mimic ants. The sheer number of ant mimics must indicate that ants are one of the most successful of all invertebrates.

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Royalty visits Peacehaven

Across the country there are loads of lepidopterists who walk transects across pieces of land to record all the butterflies present at these locations. We have them to thank for a wealth of data on the distribution and statuses of the UK’s butterfly fauna but also for a number of interesting sightings. An example of the latter was an incredible sighting of no less than 3 male Queen of Spain Fritillaries lekking around a bonfire on a farm on the edge of Peacehaven, near Piddinghoe!

These exotic butterflies were first seen on the Saturday (26 August) by Dave Harris on his transect. It’s private land, however I am incredibly grateful to the farmer Colin Appleton for allowing access, as I was able to visit the site yesterday (29th).

Upon arrival at the location we could immediately tell that this was the place! There were quite a few naturalists spread out across the narrow meadow, searching for the fritillaries. It was about 2.15pm and they had not been seen since 12.45 – which was worrying – however there were still many other nice butterflies to look at while we searched.

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Clouded Yellow – also a migrant butterfly however significantly more common!

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Small Copper

Eventually, 30 minutes after arrival (not too bad considering we could have been waiting for a lot longer!), the keen eyes of Amy Robjohns spotted one fly in and land on the ground. It proceeded to sun itself for the next minute or so before moving to a separate patch of dry earth for a little while longer. Just the one – and it appeared to be much more elusive than on previous days. I would be surprised if any are seen again after today’s forecast bad weather.

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The fritillary sunning itself

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The only photo I got that shows the large white spots on the underside of the wings, characteristic of this species.

It may seem odd that 3 were seen at this same site together, for such a rare migrant. However, they are known to travel in groups, like some birds. However, once they had arrived at the farm, they turned hostile against each other, and used the aforementioned bonfire as a lekking site. Here they would fight against each other, and even drive away innocent butterflies of other species such as the Clouded Yellows and the Common Blues. A lek is used to attract the attention of females and for the females to choose a mate. No females have been seen (yet), however they are more elusive, so perhaps we could be seeing another generation of these exotic butterflies sometime soon.

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

 

Christ’s blood covers the Lords-and-Ladies

Being only mid-April it is quite early for a number of wildflower species to be blooming, in particular Orchids. Therefore I was very pleased when I spotted quite a number of individual orchid plants, or ‘spikes’, on Good Friday.

The colour of the flowers of these orchids were purple, and they were flowering quite early in the orchid season. That meant that they were Early Purple Orchids! I was pleased that I managed to see these orchids as although they are not a particularly rare or localised species, they are a species I have never seen before.

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Early Purple Orchid (Orchis mascula) whole spike

 

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Early Purple Orchid (Orchis mascula) flower detail

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Early Purple Orchid (Orchis mascula) whole plant

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Early Purple Orchid (Orchis mascula) leaf detail

As you can see from the last photo above, the leaves of this species are covered in dark black markings. Early Purple Orchids share this characteristic with several other orchid species such as the Common Spotted Orchid and the Heath Spotted Orchid. And, as there so often is, there is folklore that surrounds the spots that are present on the Early Purple Orchid. It has been believed that this flower grew below the Cross on which Christ was crucified, and the leaf spots are the drops of Christ’s blood.

And not only orchids have these dark spots on their leaves. We came across these leaves on the same walk:

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These are the leaves of Lords-and-Ladies, Arum maculatum. When the scientific name is translated into English it becomes ‘Spotted Lily’, after the spots on the leaves. Along with Lords-and-Ladies there is a huge range of other vernacular names including Cuckoo Pint, Jack-in-the-Pulpit, Cows-and-bulls and Naked Boys. The names that are gender-related such as Lords-and-Ladies and Cows-and-bulls refer to how the flowers of this species apparently look like the process of sexual reproduction:

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The flower is very clever in attracting insects for pollination. The spadix, the dark inflorescence rising vertically from the flower, has an odour resembling that of dung which is particularly attractive to a number of fly species. The flower can also produce a temperature significantly warmer, up to 15 degrees or so, than the surrounding air, which also helps to bring in pollinators. Below the spadix there is a ring of robust hairs, which temporarily keep the flies inside. The flies are able to escape but usually only when they have come into contact with the male flowers inside the spathe (the green hood surrounding the spadix) and have therefore been covered in pollen. Once the fly has escaped then it will fly to another Lords-and-ladies flower, again attracted by the faecal scent. Some of the pollen on the fly will find itself inside the female flowers – which are situated below the male flowers – allowing fertilisation to take place.

Both Early Purple Orchids and Lords-and-ladies are common plants in the UK at this time of year, definitely species to look out for. Early Purple Orchids are easy to spot due to their tall and bright flowers, particularly in their favoured habitat of woodland and woodland edge. Lords-and-ladies are less easy to spot due to the green colour of their leaves, however keep an eye out for them and you should be able to find some of the distinctive flowers.

 

 

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!

Tricky Zygodons! Or are they?

Last Sunday I was able to attend a field trip of the South-East branch of the British Bryological Society, to Duddleswell Valley nestled in the expanse of Ashdown Forest. The key site in this valley is a wooded ghyll, which has been a very popular location for bryologists since at least when the brilliant botanist Francis Rose visited in the mid-1950s.

Once we had waded our way through no less than eight different species of Sphagnum mosses we arrived at this famous ghyll and what greeted us was a steep and slippery slope down to the stream below us. Luckily we all made it down safely and we were able to begin!

We worked our way slowly down the ghyll, finding extreme rarities such as Campylostelium saxicola; admiring huge walls of fruiting Pellia epiphylla and finding ourselves knee-deep in shallow-looking mud. I even managed to put my foot in the middle of the largest colony of Nardia compressa in South-East England!

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A large part of the only colony of Nardia compressa in the South-East

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Nardia compressa

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Campylostelium saxicola

Near the end of our excellent and bryophyte-rich walk we came across a good stand of willow trees with many species that we hadn’t yet encountered that day. These species included a small, inconspicuous tuft of moss, a Zygodon species. There are four regularly occurring Zygodon species in the South-East and they are hard to separate in the field. To be certain of an identification to species level you really need to get out the microscope.

Therefore I took a small part of the moss back with me to work on. I was expecting it to be a tricky task that might take me a while to perfect. What surprised me was that it was quite the opposite!

The features to look at are the gemmae. The gemmae of Zygodons are single cells that detach from the moss in order to reproduce asexually, meaning that the fusion of male and female sex-cells (gametes) is not necessary. When mosses and other organisms reproduce asexually like this it is referred to as fragmentation.

Not knowing how to get the gemmae off the moss and onto the microscope slide to examine, I first tried taking a small stem of the moss and seeing if I could spot any gemmae around it. This was unsuccessful and so for my second attempt I simply tapped the clump of moss onto the slide, added a drop of water and a cover slip. I placed this slide under the microscope and I could immediately see several gemmae under 100x and 400x magnification. That was much easier than I had expected!

Next came the actual identification of the Zygodon. The very helpful Brad Scott had narrowed my moss down to two species, Z. conoideus and Z. viridissimus. He also supplied photos of the gemmae of both conoideus and viridissimus, so all I needed to do was compare the gemmae of my moss with Brad’s excellent photos. It was clear: my moss was definitely Zygodon conoideus!

This experience has certainly shown me that not everything that needs microscopic examination is difficult. Certainly some species require very fiddly work to separate but that is not always the case.

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My photo of a gemma of Zygodon conoideus

Purple Sandpipers at Newhaven

With the year coming to an end I though that it would be a good idea to go out on one last excursion in search of wildlife. I chose Tide Mills, a long-abandoned coastal village near Newhaven in East Sussex which has a record of scarce or rare birds like Rose-coloured Starling, Red-backed Shrike, Grey Phalarope and Tawny Pipit.

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The Red-backed Shrike at Tide Mills, 25 September 2016

The reason why I chose to visit Tide Mills was due to a few interesting birds that had been recorded there in the last few days. Firstly, a male Serin had been spotted near the village ruins. These are usually only rare passage migrants in the UK, however as it is December and far from the main autumn or spring migrations I am not sure why it turned up here. Since the 1970s there have been a few breeding attempts in the southern and East Anglian counties however never more than a couple each year.

Also, there is a strong wintering population of a dozen or so Purple Sandpipers that visit the pier at Newhaven. Along with Brighton Marina, this pier is one of the most reliable sites to see Purple Sandpipers in Sussex and as I had not yet seen one in Britain before I was keen to take a look.

Unfortunately the Serin had either moved on or was hiding well within its bush when we visited. Despite many people searching for it we had no luck, which is a shame, however we still had the Purple Sandpipers to look forward to.

Walking along the pier we looked down at the struts below us, which is where the Purple Sandpipers usually spend their time. However we hadn’t seen anything by the time we reached the halfway point which was worrying! We continued to walk along the pier, still looking down. Fortunately I looked up for a brief moment to see how much of the pier we had left to walk and to my surprise I spotted a group of medium-sized dumpy birds sitting on the concrete beams projecting off the top of the pier!

We slowly made our way closer until we were as close as we could get. We could see that most were indeed Purple Sandpipers, 12 in total, along with a few Turnstones. They were barely wary of us at all, most of the time simply eyeing us from just a few metres away. I suspect that the high tide probably pushed the sandpipers off the concrete foundations below, which allowed us to get such good views of them. Not what I was expecting at all! We spent a little while with these very cooperative birds taking many photos, some of which I have attached below.

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