In like a Lion, out like a Lamb

In March, the surveying season starts. And when it starts, it starts with a bang.

After weeks of inaction due to Covid restrictions, the second week of March has been filled with the resumption of surveys of all types.

First off was Sunday morning, 14th March, surveying Maer Lake for the BTO’s Wetland Birds Survey. There were a limited number of bird species, although there was an unprecedented mixed flock of over 300 gulls, as most of the winter waders had left although a pair of Shelduck remained giving hopes of another breeding year. Black-tailed Godwits were also noted; they seem to be residents now.

This was quickly followed the next day by a visit to Tamar Lakes, again WeBS at Lower and Upper Lakes. This was similar to Maer with few winter visitors although the annual Goosander visitation had not come to an end with four remaining on the Lower and two on the Upper Lake.

Mixed flock of Gulls at Maer Lake

The temperature was around 13℃ so high enough to commence the Bee walk in Coombe woods. Although not many were seen, we did find that where Willows were in flower, they had attracted quite a few Buff-tailed Bumblebee queens high up in the canopy.

Thursday 18th was the day we planned the quarterly bird transect around Bude Marshes. Normally this is a group effort, but to conform with Covid regulations, Duncan and I have been the only two participants for a year now. Numbers of species are definitely down; from 31 last March to only 24 this year although it did include Shelduck, Curlew and two Cattle Egret.

Cattle Egret - Bude Marshes

During the month, the invertebrates had begun to appear from their winter absence. Gorse Shieldbugs, 7-spot Ladybirds and Buff-tailed Bumble bees were appearing at the beginning of the month in that short warm spell.

We had the very cold and windy middle of the month, typical of March until the last week when we had the mini heatwave. Butterflies - Small Tortoiseshell and Brimstone, and those harbingers of spring, Skylarks and House Martins.

During this cold spell, I completed my three Riverfly surveys adding another beetle to my growing species list - Oreodytes sanmarkii, a tiny 2-3mm water beetle that zooms about in the water column of stony streams.

2-3mm Water Beetle - Oreodytes sanmarkii

The 30th was a very warm day, hitting 18℃ when I recommenced my Butterfly Transect along the Tidna. Although there were only four butterflies of three species - Speckled Wood, Peacock and Small Tortoiseshell, other invertebrates were recorded. Common Carder and Red-tailed joined the Buff-tailed Bumblebees along with more Gorse Shieldbugs and 7-spot Ladybirds.

Of great interest were the Oil Beetles. I recorded both Violet Meloe violaceus and Black M. proscarabaeus in the Tidna Valley as well as the triungulins of the Violet species. These are bee parasites. The adults lay eggs in sandy soil near a bee nest . These in turn hatch into triungulins (so called because they have three claws on each leg)which emerge and crawl onto flower heads and lie in wait for a passing bee. They hitch a ride into the bee’s nest where they eat the bee’s eggs before changing into grubs where they remain until emerging as adults the following year. The cycle then repeats.

Clockwise - Violet Oil beetle, triungulins, Black Oil beetle

On the last day of the month another butterfly, a Red Admiral was recorded along with the first Green Shieldbug of the year.

To top it all off, life has continued to develop in my Lockdown Pond. I built it during Lockdown1 from 8th April and filled it with water on the 16th. At the begining of March, I found a Palmate Newt under a log and transfered her into the pond where she vanished into the bottom mud.

Palmate Newt

 In the last few days of the month I have seen, a Backswimmer (Notonecta), Pond skaters (Gerridae), a Whirligig beetle (Gyrinus) and three Dragonfly nymphs. As I noted ovipositing Broad-Bodied Chasers last May, these would appear to be its progeny.

Broad-bodied Chaser nymph

Those last few days of March were gentle, warm and windless - almost as gentle as the large numbers of new-born lambs in the fields.

Blogs I follow

https://downgatebatman.blogspot.com/

https://maryatkinsonwildonline.blogspot.com/

Spring has sprung.

February thought it was March - we had a very cold snap when temperatures hovered around freezing here in North Cornwall.  Then there was a very cold easterly wind when eventually backed southerly and became warm, but just as strong, eye-wateringly strong.

My pond was frozen for almost a week but Water Boatman and Diving beetles survived the ice and could be seen foraging in the warm weather.

Then, Spring arrived.  In the last few days of February temperatures rose to double figures.

Wild and garden daffodils began to flower.  A large queen Buff-tailed Bumblebee disappeared into one of their trumpets.  Honey bees massed on my neighbours flowering Heather.

The first invertebrates had awakened from their winter sleep.

Gorse Shieldbug

After a couple of months of checking on local Gorse bushes, we saw our first Gorse Shieldbug on the 25th and every day since.  7-spot Ladybirds are about too whilst overhead, a Buzzard mewled and a Great-spotted Woodpecker drummed in a nearby copse.

7-spot Ladybird

Along the hedgerows, it seemed that every tall twig held, alternately, a Robin or a Dunnock each spaced about 100 metres apart and proclaiming his territory.

And on the 25th the first butterfly roused from hibernation; a Peacock and a Small Tortoiseshell on the 28th.

Spring has most definitely sprung.

Blogs I follow

https://downgatebatman.blogspot.com/

https://maryatkinsonwildonline.blogspot.com/

Grisly nature

Folklore had these parasitoid worms forming from the dropped hairs of horses when they were frequently found in horse troughs.

The Gordian knot is an illustration of a problem without a solution. An ox-cart which delivered a peasant named Gordias into Phrygia who became its king, was tied up with a knot so intricate that is was not possible to undo it, but whoever did would rule the whole of Asia  Alexander the Great tried and failed so sliced it in half with a stroke of his sword hence the Gordian knot/

A phylum of parasitoid invertebrates comprising the marine Nectonema and freshwater Gordioida. There are 350 different known species throughout the world.

Adults can reach a length of between  50 and 100mm and in extreme cases 2m but only up to 1mm in diameter.

They have an external dark brown cuticle, which is almost all muscle which gives them a hard and wiry feel. This muscle arrangement results in them  twisting into intricate knots - hence the genus name Gordius resembling the classical Gordian Knot. 

Nematomorpha showing the eponymous knotting behaviou

They lack any excretory, respiratory or circulatory system.  The eyeless head may have a darker band below the paler tip.

The tail end of females is rounded but males of most genera genital papillae showing as a cleft tail.  Males of Gordius genus have a crescent-shaped fold above the two lobes.

Male nematomorpha with bifuricated anterior.

They exist in their external adult form purely to reproduce.

The life cycle is complex and almost wholly parasitic.

Long strings of gelatinous eggs are laid in freshwater.

From these develop planktonic larvae which have a boring apparatus with which to enter its first host, aquatic invertebrates typically diptera or trichoptera larvae.  Once inside this host, they encyst in the gut of the invertebrate.

In turn, these invertebrates are predated upon by freshwater or terrestrial invertebrates, typically Coleoptera or Orthoptera with Carabidae being a common host.

Once inside this host, the larvae develop into the adult worm-like form.  They grow to fill the internal cavity of the host but also influence it to seek out and enter water where the host drowns.  Once this is achieved, the adult Nematomorpha will abandon the host and seek a mate to reproduce in freshwater where the next season’s eggs are laid and the adults die.

 The National Biodiversity Network shows 251 records, the majority of which were recorded in Wales and a few in Scotland.  The South West has no records at present.  However over the last three years specimens have been increasingly recorded in Cornwall and on Lundy. 

Although reportedly adults emerge from their host in late summer or early autumn, on Lundy adults are typically found in shallow temporary puddles on the island road in November and December.  In Cornwall, they have been recorded during Riverfly surveys in small streams in April, August, September and November.

I always search shallow puddles of the picture that eludes me, that of an adult emerging from its host.

Blogs I follow

https://downgatebatman.blogspot.com/

https://maryatkinsonwildonline.blogspot.com/

Lockdown Pond

During lockdown, I fulfilled a long-standing ambition and built a pond.  I'd been promising myself that I would do this for years, but never got around to it. During April I bit the bullet and made a start.  

The result is a modest affair, 3m x 2m with a maximum depth of 0.4m in a very flat grassy garden bordered by fields.  

Lockdown Pond

I added water on 16th April and within a matter of hours, it had attracted three different species of water beetle.  Within this short space of time, there were around 50 tiny 2-3mm Helophorus, four medium-sized Hydroporinae and a couple of larger Dysticidae.  On the 19th a Pond-skater (Gerridae) visited briefly, but did not stay.  The Helophorus mass-attacked anything organic that fell into the water and the Helophorus could be heard hitting the plastic liner where they immediately started mating furiously.

Left Dytiscidae and a mass of voracious Helophorus demolishing a slug

Hydroporinae

The birds like it. All species seen in the garden have used the pond to drink or bathe with a blackbird seen gathering damp mud to line her nest and once a couple of swallows skimmed low but did not stop to drink.  Birds seem to gather near it, frequently settling comfortably in the grass.

I wanted the pond to colonise naturally, which it is doing for the fauna, but I admit to helping the flora.  I have replanted a couple of  Common Rush Juncus effusus and Water mint Mentha aquatica at the bog end of the pond and acquired three Common Spike Rush Eleocharis palustris plants which I planted in the shallow water's edge, and I've also added a small piece of Common Water Moss Fontinalis antipyretica.

The last couple of weeks have been challenging through lack of rainfall.  I could almost watch the water level falling as the contents of the pond evaporated.  Last week, I emptied the last 75 litres out of my water butt but still the level continued to fall.  I have joined the Wildlife Ponds UK  Facebook group 

https://www.facebook.com/groups/2122154031407805/ and looked there for advice.  The recommended strategy was to use tap water but fill the pond through a spray nozzle to help remove the Chlorine from the tap water.

This morning (28th May) I sprayed the pond and raised the level by a couple of inches, a much more acceptable depth.  Once done, I contemplated my satisfyingly deeper pond and spotted another new arrival.

Lesser Diving Beetle - Acilius sulcatus

This was a much larger and very busy water beetle.  It was about the size of a thumb-nail with yellow horizontal markings across its head and broad grey stripes along the elytra - a Lessser Diving beetle, Acilius sulcatus!

As if this was not enough, an hour or so later, two female Broad-bodied Chasers Libellula depressa had found the pond and were ovipositing in it.

Broad-bodied Chaser - Libellula depressa

Never mind the South West Water bill, I'll have to keep topping up the water level to ensure the survival of their nymphs.