Quickly and cloudily at Dene Park

I have been neglecting Dene Park quite a bit recently, so I was glad to get back there at about 4 this afternoon, although it was now quite late in the day and cloudy, even threatening a bit of rain I thought! What a contrast to this morning which was sunny and almost too hot to sit outside by 10:30!

No butterflies and very few insects of any sorts at all really. There were some tiny flies on the Creeping Buttercup along the main path heading towards the dip down to The Scambles.

I was very pleased to see my first spike of Common Agrimony (Agrimonia eupatorium) of 2014 out in about 50% flower, alongside the path through Knight's Wood (I am obviously very slow). This is one of the several Rosaceous foodplants of the Grizzled Skipper, although there is little chance of seeing one of these at Dene Park, as it is not a Chalk Downland woodland, but on the Lower Greensand, well South of the North Downs.

Agrimony is a perennial herb, having a long black somewhat woody rhizomatous root. The plant is 30 - 60 cm tall, with a long, thin, tight flower spike. Old names include Church Steeples, Cockeburr, Sticklewort and Stickwort. The leaves are much larger and more sub-divided at the base of the stem than they are higher up. The leaflets are separated by much smaller leaflets, and get bigger as you get closer to the tip of the leaf. The whole plant is softly hairy overall.

There may be larger plants within the species taxon, maybe a subspecies, A. eupatorium var sepium, found in places like Durham, which are said to be more fragrant, but this should not be confused with the separate species, the Fragrant Agrimony, Agrimonia procera. This species has been noted at Bedgebury Pinetum - by the Wild Flower Society no less! There is a BSBI crib, incredibly useful to separate the two species!  http://www.bsbi.org.uk/Agrimonia_Crib.pdf

Agrimony is a traditional medicinal herb, the Greeks commonly using it for eye problems, while the Anglo-Saxons used it to treat wounds and to slow bleeding. The flowers are said to have a scent reminiscent of apricots.

Amongst many other ingredients the agrimony flowers contain the flavenoid quercetin which is anti-oxidant, anti-inflammatory and also gives the flowers their yellow colour. It is also relatively rich in tannins, hence its use sometimes as a gargle.

The whole plant yields a pale yellow dye in September, and a deeper yellow later in the year.

The Bourne Valley to Malt Cottage

Walking down through the Green Lane Shaw, there were a fair number of hoverflies patrolling their territories. Most I thought were the Marmalade Hoverfly, Episyrphus balteatus, but this was a Myathropa florea that was buzzing loudly and had taken control of some leaves in a patch of sunlight.

This is Leucozona lucorum, a rather tatty specimen from the currently declining first generation.

Many of the herbaceous plants were suffering from the dryness of the soil and the heat, and were already flagging this early in the season. The Hawthorn fruit continue to swell into haws - it seems that the season is progressing very quickly indeed! There is one on the left that appears not to have been fertilised. The epidermis of the fruit is slightly hairy, at least at this stage.

Here you can see even more clearly the swelling inferior ovary, with its sparse hairs and the remains of the calyx and the other floral parts above it, apart from the petals which dropped off weeks ago.

Further along the walk the Norway Maple keys were also developing gorgeously:

The elms were starting to show the Elm Leaf Gall,

In the Green Lane, I found a moderate stand of Hedge Woundwort, Stachys sylvatica, at the Bourneside end of the shaw.

As I  moved out into the arable fields along the river, the Honeybees were working the flowering Forage Beans across the fields.

The Vetch I saw most today was in the Common Vetch aggregate, Vicia sativa. This plant looks like ssp. segetalis as in the BSBI plant crib, as it seemed more or less isophyllous, the tendrils are branched, with a clear slightly bi-coloured flower (standard somewhat paler than wings). There is more taxonomic information here http://archive.bsbi.org.uk/Wats12p1.pdf. This includes the suggestion that the calyx teeth should be shorter than the calyx tube, as here. It would be nice to check the pods and the seeds later, perhaps I should mark some typical plants so that I can go back to them in a few weeks.

This a close-up of the flower.





This ant looks yellowish, perhaps because the light is behind it. It had come down from the flower above.

This shows the dark patch generally seen on the stipules, and the hairs covering the plant.

This is the leaflets close up - its fascinating how the genes can apparently code for such a variety of leaf shapes! I wonder how long it would take a computer programmer to code for growth to produce the same results? Are the slightly spiky tips of the leaflets defensive or for some other purpose? The spikes are a bit longer in the currently cultivated form Vicia sativa ssp sativa.

Most of the Buttercups I saw today were Creeping Buttercup, Ranunculus repens. However there were patches of Meadow Buttercup, Ranunculus acris around, including at the edge of the crop in the field to the North of the bridge over the Bourne leading towards Barnes Place.

I think the beetles are flea beetles:

Many of this plant's flowers are already setting achenes, very similar to those of the Creeping Buttercup. Interesting pattern of light in these!

and this one shows the same pattern as well - air spaces around the seeds compared to double thickness wall edges perhaps? Or is it just that the seeds inside the fruit are themselves white? Anyway it's very pretty.

Here is Hedge Mustard, Sisymbium officinale, this one's buds just opening.

It was  nice to see some birds flitting around the hedgerows. The nicest I thought was this male Yellowhammer on the Eastern side of the reservoir b y Malt Cottage.

Even more heavily cropped, this Linnet:

The Bourne Valley

I walked down from the Access Trail along the Bourne Valley looking for birds, butterflies and planning issues!

It was very nice to see some Small Tortoiseshell Butterflies, Aglais urticae, sunning themselves along the path. I recorded 6 for the Kent BBCS website. This year I seem to be seeing more of these than I have in the last three years, which is very good news as their numbers sank like a stone a few years ago. I cannot tell whether these are the last of the overwintering individuals, or the first of the mid-summer ones.

There are starting to be more damselflies around and I saw a good male Common Blue on the nettles by the river.

After Monty had had a good runabout, I put him on the lead and allowed him to cool down while I tried to work out the ghostly birds flitting in and out of the shadows. There were a family of Great Tits with newly fledged young, which were seen in deep in the canopy but very difficult to photograph. The light face patch looks more yellow and the features in general are only poorly defined, although the wing stripe is a good clue for identification.

There were two magpies in the general area of Hayes Farm, apparently one smaller than another, so I suppose that the smaller one might have been a recent fledgeling.

The Hucking Estate - different buttercups

Bulbous buttercup to come when I get back from the bat survey.

Bod Petrual - Cheilosia and Buttercups

A really great Forestry Commission site in deepest Denbighshire, even if I didn't hear the hoped for wood warblers and Redstarts on my late morning visit today! This is one of the fine parts of the huge Glocaenog Forest.

This Cheilosia on Creeping Buttercup, Ranunculus repens, really ought to be the albitarsis/ranunculi group. The first thing to note is that this insect is a male with a blue-black thorax and slightly darkened wings, and generally dark legs:

This picture shows what appears to be a fairly dense covering of pale hairs on the eyes

Moving on to the more botanical side of things, the Cheilosia above is feeding on a Creeping Buttercup flower, Ranunculus repens (L.).

The Creeping Buttercup is a herbaceous, stoloniferous perennial growing to 50 cm tall. There are many named subspecies. It has both prostrate running stems, which produce roots and new plants at the nodes, and more or less erect flowering stems  arising from a short stout "caudex" with a rosette of leaves. The basal leaves are divided into three broad normally stalked leaflets 1.5–8 cm long, shallowly to deeply lobed, borne on a 4–20 cm long petiole; leaves higher on the stems are smaller, with narrower leaflets. The leaves may be white-spotted. Both the stems and the leaves are finely hairy. The flowers are bright golden yellow, 2–3 cm diameter, usually with five petals. The nectaries are easily seen as tiny pockets at the base of the petals. The fruit is a cluster of achenes 2.5–4 mm long. It grows in fields, pastures, woods, gardens, parks, roadsides and wasteland and prefers wet soil.

Useful ID points are the spreading (not reflexed) sepals, the grooved stems and the stalked (petiolulate) terminal lobe of the trifoliate leaves. Interestingly there have been no reports of a mycorrhizal association.

Like most buttercups, Ranunculus repens is poisonous, although when dried with hay these poisons are lost. The toxin protoanemonin (apparently a break-down product of ranunculin) is not very stable and loses its potency when dry, so buttercup is not generally toxic in hay. The taste of buttercups is acrid, so cattle generally avoid eating them. The plants then take advantage of the cropped ground around it to spread their stolons.

Creeping buttercup spreads by seed and by long branching stolons that root at the nodes, forming new plants (ramets). The stolons may also regrow from cut portions to some extent. In more established woodland and grassland communities, this plant increases mostly through stolons unless the soil is disturbed. In dry conditions, flowering and seeding is more prevalent and in wet conditions, stolons are more plentiful. Seeds can germinate and seedlings can grow even under water-logged conditions. The plant is also said to be spread through the transportation of hay, implying that the seed may be present, I would imagine!

The plant is a serious invasive weed in places like North America and New Zealand. Here is a link to a useful Canadian paper on the biology of this minor threat to their ecosystems and agriculture.  http://pubs.aic.ca/doi/pdf/10.4141/cjps90-135

One of the reasons creeping buttercup is so competitive is that its stolons respond to the environment. Under favourable conditions, plants form more stolons through branching. However, when nitrogen or water is limiting, stolons tend to be longer and un-branched allowing longer distance “sampling” of a number of potential sites until more suitable locations are found. When favourable conditions are discovered, stolon branching resumes, allowing rapid local colonization to take advantage of the available resources. In general, short stolons are produced in dense turf and much longer ones appear in open fields or woodlands.

Depending on the temperature, creeping buttercup either overwinters as a rosette or dies back to ground level. In either case, the nutrients stored in the short swollen stem produce rapid growth in spring, between April and June. Stolons grow from the leaf axils in spring and summer and growth peaks in late summer. Stolons connecting parent and daughter plants usually die off in autumn, leaving the plantlets separate.

Flowers can appear from March to August with seeds soon after. Each plant produces from about 20 to 150 (this may be an over estimate) seeds. Seeds can remain viable in the soil for at least 20 years, and up to 80 years, especially under acid or water-logged conditions. Seeds are dispersed by wind, water, birds, farm animals, rodents, and other animals by adhering to them with the hooked seeds. They exhibit dormancy and also sustained viability in the seedbank.

Excessive contact with the sap of the plant can cause skin blistering in humans, and various toxic effects in cattle if they eat it in excess because they there is little else and they are hungry. Unfortunately, livestock occasionally develop a taste for buttercup and consume fatal quantities.

The age of meadows up to 200 years old can be roughly estimated by the number of plants in 100 that have extra petals in their flowers - you get about 1 plant with flowers with extra petals for every 7 years old it is claimed.  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2729631/ Mentioned in notes of nature. However the correlation coefficient is only moderate, in my view. This flower, photographed by chance a little further along the woodland path at Bod Petrual, turned out on closer examination to have 8 petals as far as I can see! I can just see 1 of the 3 sepals below I think.

and this one has 6 petals.

This on the other hand is another toxic plant, the Meadow Buttercup, Ranunculus acris, with a more finely dissected basal leaf. In this species there tend to be 5 (3 - 7) leaflets and in addition, unlike in the Creeping Buttercup, the middle (or each?) leaflet is un-stalked, giving a typical palmate rather than trifoliate appearance. The BSBI plant crib is very useful here: http://www.bsbi.org.uk/Ranunculus_Ranunculus_Crib.pdf

There is a photo below that of the characteristically even more dissected stem leaf. There were several scattered plants, in amongst or separated from the  Creeping Buttercup, apparently it appears at random. There were very many fewer of this species, and I didn't happen to see any Cheilosia on them.

The very different, almost linear, un-stalked stem leaves of Ranunculus acris (L.) acris, the only subspecies found in the UK - although there are three different races!

The fairly common confusion species to Ranunculus repens is the Bulbous Buttercup, Ranunculus bulbosus, of drier grasslands, which has sepals that are reflexed in full flower. I saw this behind the dunes at Warkworth last week I believe.

In the Meadow Buttercup, the flower is similar to the flower of the Creeping Buttercup, with un-reflexed (spreading) sepals, but the flower stalk is, by contrast to the Creeping Buttercup, ungrooved. Another feature is the chromosomal number. Ranculus repens is generally a tetraploid plant (N = 32) based on N = 8, while Rancunulus acris is also a tetraploid (N = 28) based on N = 7.

There were plenty of other plants growing in profusion, and a few were even in flower. It was particularly nice to see the Cuckoo Flower, Cardamine pratense, so long after all the ones in Kent are long over.

Cliffe

As I arrived, over-encumbered with gear, a car drew up beside me and asked me the best path to the Black-winged Stilts! I denied any knowledge but was tempted enough to head towards Flamingo rather than the usual lookout over Radar pool. Having admired the Avocet chicks I finally came across the Black-winged Stilts elsewhere, guarded 24/7 by a very mice but very tough looking chap with a dog partner, a large Alsatian.

He doesn't generally train the dog to bite (too much paperwork if there is an incident) but simply to leap up and knock the perpetrator over, - this usually knocks the wind out of the baddy, possibly breaking a rib or two in the process, and the absence of biting reduces the risk of the dog being separated from his handler by the police after the incident, which even if only temporary, would be unthinkable and intolerable to both.

This is the male Black-winged Stilt (very henavily cropped) standing guard

and this is the female (even more heavily cropped) incubating the eggs on the nest, just to the right of the standing male.

The scrub was fairly full of birds, Whitethroats, Linnets, Goldfinches, Nightingales, Blackbirds and here is a nice Long-tailed Tit.

and here is a male Cuckoo, that was calling for a long time from this area of scrub by the Flamingo Pool::

There were a lot of Black-headed Gull chicks around, and here is one that had got into the water.

Whetsted Gravel Pits

There was a single Common Tern, Sterna hirundo, fishing the gravel pits stylishly and successfully! In the first picture, where the bird is dark against the lightness of the sky, I think I can see the light (sometimes called translucent) panel in the middle of the wing that is said to help to distinguish this bird from the Arctic Tern, Sterna paradisaea, where much more of the wing is said to be translucent.  That I don't find this convincing says rather more about my very poor skills as a birdwatcher than it does about Tern field characteristics!

Rather clearer here are the black tip to the otherwise comparitively light red bill, and the not excessively long tail streamers. It is also easier to see the black outer webs on primaries P10 - P5.

Above I think I would only just agree that the dark trailing edge to the wings in the outer primary section bleeds well forward into the rest of the wing but on the lower side there is a limited and sharper dark trailing edge. This does not taper off inwards. A limited dark trailing edge not bleeding forwards to form a dusky wedge on the upper side is said to be more characteristic of the Arctic Tern, and the dark trailing edge on the underside should taper off inwards in that species.

The bird seemed reasonably successful and the one time I followed a dive a small fish was apparently fairly easily taken, as shown below. Common Terns are said to be more likely to dive directly rather than hover briefly before diving as Arctic Terns are generally said to do (Bird Forum), and this bird seemed to halt, twist (bank sharply) and dive almost back on itself but nearly vertically into the water, perhaps flattening out a bit as it hit the water surface. However BWP claims that they do hover but less rapidly than the Arctic. It would be interesting to follow the sequence more exactly with high speed shooting, or even video.

Common Terns are flexible feeders but generally are dive-plunge feeders, often but not always submerging 20 - 30 cm. They also surface feed or even plunge from perches. The main prey is fish, but the diet also includes shrimps and other crustacea as well as insects perhaps taken from the surface. This particular bird just seemed to be plunge-diving for fish!

A more important point though is why hasn't it eaten the fish instantly, as BWP claims it should have done.. Where is it taking it? To a partner or a nest? Or is this bird just passing through, and just being slow to eat its catch?

Perhaps its not too surprising to see an individual inland, but its difficult to know if this is just migrating through the area, or perhaps specifically looking for an inland site to breed upon. This could be a late migrating bird, just arrived following the long journey North from the wintering grounds of West Africa. What a pity there are no nesting rafts on these pits. Once a pair has chosen a nest site they may return to the same site year after year (17 years is apparently the current record until one of the pair failed to return).

After fledging and learning to fish on their own, juveniles may start to move South either in family groups or small flocks of juveniles only. They may trek backwards and forwards for anything up to 3-4 years before first breeding, but sometimes breeding can start at 2 years old. When they are old enough to breed, they may breed in the colony they were born in, or nearby.

Mates do not seem to associate closely in the winter quarters, but arrive at the nest site paired up, having found each other perhaps in the winter quarters prior to departure, on passage, or in and around the colony. They arrive initially at a roost close to the colony and already paired birds can be recognised by roosting closer to each other than the average.

Once the next territory is established it is used for courtship, copulation, pair-bonding, nesting and initially (up to 23 days) concealing and feeding the young.

Population is about 15,000 in UK, fairly stable and the smaller inland population appears to be growing. This pattern not repeated consistently across Europe.