May is the month when the rhododendron, azalea, and yellow flag start to flower; the trees come into leaf; the last of the summer migrants return and when the dawn chorus is at its peak.
Nightjars usually start arriving from their winter quarters in Africa in May. The males arrive first, with the females following in mid-May. These nocturnal birds roost on the ground in heathland areas during the day and feed on moths at night. When glimpsed at dusk the nightjar resembles a large swift and can be heard ‘churring’. Keep an eye out for the real swifts which also return from Africa this month – make the most of them as they are the first migrants to leave in August.
The first blackcap was heard singing on 6th April, four years earlier than last year. Migrants still to appear include garden warbler, wood warbler, sedge warbler, spotted flycatcher, pied flycatcher and hobby. Hobbies are our only full-scale sub-Saharan migrant falcon. They arrive here this month and feed not only on birds, but also on insects, especially dragonflies. Their breeding season begins in early May with their chicks often just fledging in mid-August. This is an excellent time for them to learn to feed as there are plenty of young swallows and martins to chase as well as lots of dragonflies. A peregrine falcon was seen chasing the swallows over the lake on 1st April.
Many birds are now feeding young. Due to the warm Spring some of the first warblers, song thrushes, robins and blackbirds have already fledged. Goldfinch and siskin have been recorded throughout April, with greenfinch visiting the feeder at the aerial walkway.
There are several broods of ducklings on the lake – the first brood hatched out on 14th April, with some mallards still sitting on eggs, along with coots and moorhens. The first coot chick was recorded on 8th April, with the first moorhen chick on the 16th. The new pair of great-crested grebes are sitting on eggs; the dry April has ensured that their nest hasn’t been washed out half way through sitting as in previous Springs. Stover’s solitary grebe left the lake on 10th April, presumably to find another mate. The female swan laid 9 eggs by 28th April , and all being well the eggs should hatch in five weeks’ time. There are three pairs of mandarin duck at Stover – the males are visible on the lake and ponds, with the females presumably sitting on eggs. The pochard, tufted ducks and black-headed gulls have now left the lake, however several herring gulls and lesser black-backed gulls have been present throughout last month. A common sandpiper were recorded on 25th April. This bird is the most likely wader to be seen inland. It is a summer visitor and is easily told by its typical flickering-wing flight low over the water, and habit of bobbing its head up and down when at rest. It is usually seen at Stover in April. The goosanders left the lake on 8th April (two days earlier than last year).
Following the appearance of their aphid prey many species of ladybird have started emerging from their winter shelters. April has seen an increase in butterfly numbers. The first orange-tip, small white and small tortoishell were spotted on 5th April, joining the brimstones, peacocks, red admirals and commas which appeared in March. Speckled wood butterflies were first seen on 9th April. Keep an eye out for holly blues which are on the wing at the moment (first recorded on 5th April) and can be easily mistaken for common blue butterflies. The rare white admiral butterfly should be on the wing this month. White admirals spend a lot of time in the tree canopy but will also come down to ground level where they feed on bramble blossom. Honeysuckle is important to these butterflies as it is the caterpillar’s food plant. Pearl-bordered fritillaries should be on the wing this month but are declining nationally; they favour yellow and purple plants to feed from, with bugle being their favourite.
The first damselfly of the year, the large red damselfly, was recorded at Stover on 5th April, nine days earlier than last year. Other dragonfly species have yet to emerge. In particular look out for the rare downy emerald dragonfly which should be on the wing this month. The downy emerald is a handsome metallic bronze-green dragonfly with a distinct covering of yellow downy hair, which is particularly noticeable on its thorax. The male, who has a clubbed tail, patrols along the tree-lined margins of the lake and ponds.
Cockchafer beetles (also known as maybugs) are usually flying around in May. They are mainly nocturnal and emerge during the middle of the month after spending the previous three years as a white, root-feeding grub. Stag beetles also start to appear in May after feeding in dead wood as larvae for five years. Once an adult they only live for a few weeks using this time to find mates and lay eggs.
With the increase in numbers of flying insects bats should start to become more conspicuous at dusk as they fly over the lake feeding. During an April survey of the bat boxes soprano pipistrelle bats were recorded. Hedgehogs court, and badger, stoat and fox cubs are active above the ground in May. Roe deer hinds will drop their kids from mid-May onwards. The young stay hidden among the bracken and grass, not moving until their mothers return. Many of the freshwater fish in the lake, especially the rudd and roach, can now be seen at the water’s edge as they spawn. The smooth shelled terrapin was seen for the first time after its winter hibernation on 7th April, joining the red-eared terrapin which was recorded on 15th March.
The large Monterey Pines in the car park will soon start to shed huge quantities of pollen, covering the cars in a luminous yellow dust. Other wind pollinated trees, such as oak and beech, flower before their leaves obstruct the drifting pollen. Holly, horse-chestnut and hawthorn also flower this month displaying their more obvious insect-visited flowers. Just before the trees are in full leaf and shade out the woodland floor completely, the spring flowers have their chance to grow, flower and attract pollinating insects. Most are powered by food stored in underground bulbs or stems. These include bluebells, ramsons and violets which are already out in profusion at Stover. Common-spotted orchid leaves are just starting to appear. The ferns are now uncurling and the horsetails are coming up around the lake path and in the marsh. Cuckoo flower (ladies smock) is out in abundance in the marsh also. Along with garlic mustard, this plant is the orange-tip butterfly caterpillars’ favourite food plant, so keep an eye out for the single eggs which turn bright orange shortly after being laid. The marsh marigolds are in flower in the marsh. Yellow archangel and celandine are in flower along with sanicle, ground ivy, yellow pimpernel and herb robert. Lords-and-ladies are also in flower and give off a foul stench attracting the flies which pollinate it.