Parish Nature Notes for May 2013 - John Wright

May 1st was warm and sunny and cuckoo-flower (also known as lady's smock or milkmaids) was visible as splashes of pale pink in damp grassland south of the Sherford River. However, this year it was flowering around two weeks later than is usual. The name cuckoo-flower came about because in a normal season the first flowering tends to coincide with the arrival of the cuckoo in mid-April.

Cuckoo-flower

Cuckoo-flower

Photograph: Ken Dolbear

The first few days of the month also saw the rather late appearance of the distinctive males of the orange-tip butterfly patrolling in gardens and the wider countryside after emerging from the chrysalis. Birds rapidly learn that these brightly-coloured males are best left alone because they are distasteful. In contrast, the females have grey rather than orange tips to the forewings and spend much of their time hiding amongst vegetation. This is particularly effective as the underside of the rear wing has a delicate pattern of mottled green. Cuckoo-flower, honesty and particularly garlic mustard are favoured by female orange-tip butterflies when laying their eggs.

Female Orange-tip

Female Orange-tip

Photograph: Ken Dolbear

On my first walk around Wareham Forest/Morden Bog on the 3rd May it was warm and sunny. There were plenty of brimstone and peacock butterflies on the wing plus green-veined whites, small tortoiseshell and my first speckled wood. This last species was on the wing in late March in 2102. Many summer migrant birds were singing including a sedge warbler offering its frenzied song from a hedge, clearly just moving through. On the heathland, loose colonies of linnets had established themselves on areas of flowering gorse and males with their red forehead and breast were giving their varied twittering song.

Male Linnet

Male Linnet

Photograph: Ken Dolbear

On the 6th there were several large red damselflies emerging from the vegetated pond on Great Ovens Heath. After the larvae have crawled from the water onto emergent vegetation and the adults have emerged from the larval case and expanded their wings, their maiden flight takes them well away from the pond. This enables them to harden their bodies, become fully mature and develop their full adult colours. Only then will they return to the pond to breed.

Mature male Large Red Damselfly

Mature male Large Red Damselfly

Photograph: Ken Dolbear

The next day I came across some wild arum in flower on a shaded roadside verge. The central purple structure (spadix) is surrounded by a large bract (the spathe) the lower part of which forms a cup enclosing the lower part of the spadix. Hidden within the cup around the base of the spadix are the female and male flowers and the top of the cup is sealed with a ring of sterile bristle-like flowers. In pollination, small flies are attracted to a meaty smell, push past the sterile flowers into the cup and and are trapped. If they are carrying pollen from another flower they pollinate the female flowers and collect pollen from the male flowers. They are only allowed to escape from the cup when the upper sterile flowers begin to wither. Much later in the season a column of red berries can be seen on the remains of the spadix.

Wild Arum

Wild Arum

Photograph: John Wright

Over the next few days the variety of spring flowers on roadside verges increased and in deciduous woodland east of Sherford Bridge, native bluebells were coming into flower. Popularly regarded as our national flower, the fragrant flowers mainly hang from one side of the stem. A potential threat to this plant is the garden bluebell, which is a hybrid between the Spanish bluebell and the native bluebell. Garden bluebells have broader leaves and broader flowers that spiral round the stem. Unfortunately, the garden bluebell is usually fertile and becoming widely naturalised and it would be unfortunate if it were to invade our native bluebell woods.

Native Bluebells

Native bluebells

Photograph: John Wright

On 16th May the Great Crested Grebes on Morden Park Lake were attending their nest, a pair of grey wagtails were at the spillway and summer migrants included a spotted flycatcher, a male redstart singing near Decoy Cottage, a pair of hobbies over the Old Decoy Pond and swifts flying high overhead on long curved wings. The swift is an aerial specialist and returning birds may have been on the wing continuously since they left us last August for central Africa. They feed on small insects during the day and then sleep at night by circling at high altitude.

Male Redstart

Male Redstart

Photograph: Aidan Brown

In the second half of the month I had few opportunities to get out, but nevertheless a short walk on Great Ovens Heath on the 17th unexpectedly yielded over 20 crossbills flying back and forth over the sand quarry. These fascinating birds which use their crossed mandibles to extract seeds from pine cones breed in Wareham Forest very early in the year and have often disappeared by May. Along one or two paths on the heath I was pleased to find heath dog violets again - a species which is now rare in Dorset. This year, additional plants were noticed in an area where the ground had been disturbed and vegetation had been removed from the path, so maybe this exposed a new seed bank. The accompanying photo also includes a very characteristic heathland plant, heath milkwort, with rather curious flowers in which the bright blue colouration is actually produced by two sepals and the true petals are joined together into a small white fringed tube.

Heath Dog Violets & Heath Milkwort

Heath Dog Violets and Heath Milkwort

Photograph: John Wright

The 23rd was distinctly cool and in walking west from Sherford Bridge to Morden Park Lake, there was no sign of the adult Great Crested Grebes and the nest itself was exposed to a cold wind. Either the nesting attempt has failed or the adults and any newly-hatched grebes, which would be sitting protected on the back of an adult, were not visible from my vantage point. Only time will tell! Near Decoy Cottage in Morden Bog, the adjacent 'lawn' of short-cropped grass included large patches of a miniscule member of the pea family called birdsfoot, which is very common in dry sandy heathland. The individual flowers, which are only around 4mm in length are nevertheless worth a close look. The name birdsfoot comes from the fact that once seed has set, the groupings of 3 pods resemble a birds foot.

Birdsfoot

Birdsfoot

Photograph: John Wright

By the 26th the weather had improved and I spotted a holly blue butterfly flying in the garden near a fence covered in ivy. The holly blue is the first of the blue butterflies to emerge in spring, in a normal year first appearing in April. It has two generations each year and whereas the spring generation adults usually lay their eggs on the flowerheads of holly, the summer generation chooses ivy. It is this generation which hatches from the chrysalis in spring and is often seen flying high through gardens, parks and along hedgerows. To confirm the identification, wait for the butterfly to settle and notice the characteristic silvery-blue underwing plus a series of small black spots.

Holly Blue

Holly Blue Butterfly

Photograph: Ken Dolbear

And finally, when Sir David Attenborough says in a radio interview that he hasn't heard a cuckoo for a couple of years, then you realise just how lucky we are to hear cuckoos within our parish as they as they pass through on migration or stay to breed. On most outings this month to Wareham Forest, Morden Bog, Great Ovens or Sandford Heath the cuckoo has been heard and occasionally I've had a sighting of a cuckoo in flight. The long tail, forward-pointing bill and characteristic flight with wings beating mostly below the body of the bird itself help to confirm the identification.

Cuckoo in flight

Cuckoo in flight

Photograph: Aidan Brown