The spring migration continues apace with the first showing of hobby and swift also continuous movements of swallow. Birds that are passing through on passage include wheatear and small groups of whimbrel (11). The whimbrel is a large wading bird - similar to a curlew, but smaller in size. It's long bill that curves near the tip is used to probe soft mud for invertebrates, it also has three distinctive stripes on the head. In the UK, this species only breeds in north Scotland, mainly Shetland and Orkney, where the breeding population has been slowly increasing, although it is on the red list of species, which is of conservation concern. It will probably be the call that first attracts you to this bird - usually a seven note whistle as it flies overhead. The whimbrel's distinctive call is often associated with a Celtic superstition of the 'seven-whistlers', supposedly a group of six birds looking for a seventh - hearing the call augured death or other disaster. Common sandpiper and redshank are two other waders that have stopped over to feed and take a rest. Also observed this week have been common terns. A few years ago this species bred near Ham Wall reserve. With our four 'tern rafts' refurbished over the winter, it is hoped to attract breeding birds to the reserve.
The reeling song of the grasshopper warbler has been heard this week, very rarely seen, so the distinctive song is usually the only indication that the bird is present. The 'reeling' is usually heard from low growing scrub or bramble bushes. If heard, it can appear to have moved it's location, as when it sings it turns it's head giving the impression that it's position has changed. Other bird song to experience whilst walking through Ham Wall reserve include: willow warbler, chiffchaff, whitethroat, blackcap, song thrush and Cetti's warbler. From the reedbed the song of reed warbler and sedge warbler form part of the spring birdsong on Ham Wall.
The male bittern's are 'booming' well, so standing on the first viewing platform will give you the experience of this most unusual of bird sound. With a little patience there is always the chance of seeing a bittern flying over the reedbeds. More birds of the heron family to lookout for are; grey heron, little egret and the occasional sighting of the great white egret.
On the open water great crested grebe have young, and near the viewing screens on Waltons Heath there is a sitting great crested grebe - it shouldn't be long before the young hatch. Little grebe are also present on the open water. Ducks species to see include: tufted duck, mallard, pochard, teal, shoveler and gadwall.
Birds of prey which frequent the reserve are; buzzard, maybe soaring on thermals, the sparrowhawk, flying fast amongst the reeds and the marsh harrier slowly quartering over the reedbed in search of any unsuspecting prey which can include small birds and small mammals. (The scientific name for the marsh harrier Circus aeruginosus is derived from the Greek kirkos meaning circle, referring to the harriers' habit of flying in circles. aeruginosus is Latin for "rusty coloured).
Butterflies are always a delight, and add further colour to the natural landscape. At the moment the most likely species are: orange tip, brimstone, small tortoiseshell, speckled wood and peacock.
Of the mammals that frequent the reserve it is the otter that most people are hopeful of seeing. An otter was seen this week and through our monthly otter survey's there is good evidence that this mammal is a frequent visitor to the Ham Wall reserve.
The picture below taken by John Crispin is of one of Ham Wall's bitterns flying low over the reedbed in 2009