Meadow yellow

Meadow yellow
Bulbous Buttercup (Ranunculus bulbosus) in a Devon meadow

Monday, 22 February 2010

Nuclear fallout

During last week's half-term I spent a few days with friends in Wivenhoe, Essex. Between the rain and snow showers we got out to the coast near Bradwell, infamous for the nuclear power station (currently disused). However nearby is the Bradwell Cockle Spit nature reserve characterised by its shell banks and established to protect shore nesting birds such as the Little Tern (Sterna albifrons).

On a cold February afternoon we were treated to the spectacle of wintering waders amassing during the high tide and performing their frequent sky shows. Triggered by passing raptors or perhaps just for practice, up they would go with synchronised twisting and flashing; dark then light they whirled over the waves like a mobile mexican wave. The most spectacular display however was as they flew close to the water surface like giant glitter catching the winter sun. These flocks were mainly Knot (Calidris canutus), mixed with Dunlin (Calidris alpina), Grey Plover (Pluvialis squatarola) and Ringed Plover (Charadrius hiaticula). The theory is that this community behaviour confuses predators such as peregrine, that patrol shorelines hunting such prey. Whilst we were there we witnessed a kestrel causing such a reaction.

On the shore itself we found a dead wader (see picture) which with the slightly downturned and longish beak was identified as a Dunlin. This species can be easily confused with less common species due to great variability in size and plumage colouration. It was clearly a fairly recent death, but the cause not. Interestingly further up the beach we found a dead fox and rat. Quite a death toll for one walk.

Thursday, 11 February 2010

Are Snowdrops whiter than white?

In recent winters, Snowdrops (Galanthus nivalis) have been as close as we have come to snow in the lowland gardens of Britain. In the wood at the Pinfold at this time of year, they carpet the banks with their white hanging lanterns, bringing a lightness back from the brown sludge of leaf decay. Look closer though at this early flowering plant and you will see what look like two sets of petals of differing size. These are in fact 'tepals' and the Snowdrop has three larger outer ones and three smaller inner ones. Tepal is a term used where the sepals (usually the green and leaf like outer part of flowers providing protection) resemble petals (usually the colourful part of flower). Look closer still and you will notice what look like green brush strokes on the tepals. It has been assumed that these markings act as nectar guides for insects which then incidently act as pollinators. However more recent research by Aschan and Pfanz (*) have shown that they also provide a potentially important additional area for photosynthesis. With relativeley small and late emergent leaves, these photosynthetic 'patches' assist in local production of nectar to attract insects and later with seed production. This would seem to offset some of the high energy costs of the plant devoted to reproductive structures; a bit like solar panels on a house contributing to the homes energy balance.
So next time you see a Snowdrop, bend down and have a closer look!
* Aschan, G. and Pfanz, H (2006) Why Snowdrop (Galanthus nivalis L.) tepals have green marks? Flora, 201 (8): 623-632.

Monday, 1 February 2010

Garden Birdwatch 2010

Did you take part in this years RSPB 'Garden Birdwatch'? If so, you joined tens of thousands of others in probably the worlds biggest mass exercise in nature observation; quite a testimony to the success of the RSPB. With its humble beginnings as a campaign organisation to stop the killing of ostriches for the trophy of rich women adding feathers to their hats, the RSPB now has over a million members giving it quite a voice in determining conservation action and increasingly the ear of politicians eager to tap into such a large vote.

The garden birdwatch is not really 'citizen science', but more an opportunity to engage the general public more actively in observing what goes on outside their windows and beyond the comfort of a heated home in winter. The RSPB will of course publish some headlines from the data submitted by the public announcing any change in rankings of our top 10 garden birds. Recent big risers have been Long-tailed Tits (Aegithalos caudatus), who have successfully mastered the peanut hanger. I can endorse this from my observations on Sunday, being the second most abundant species. As I child this bird was quite a sighting. In contrast the Song Thrush (Turdus philomelos) has slipped on the proverbial snake in terms of its rank, out of the top 10. Common in the past in gardens full of snails without the current proliferation of slug pellets protecting gaudy flowers. As a boy I loved finding the little 'anvils', an object used by the song thrush to smash the shells of snails. I'm glad to say that our resident thrush made an appearance in the allotted one hour. Out top bird however this year was the Great Tit (Parus major) with six seen at one time. Their aggression gives them prime access to the fat balls, their favourite food in our garden. The birds that made a no-show that I had hoped to count were the Jay (Garralus glandarius), Nuthatch (Sitta europaea) , Treecreeper (Certhia familiaris) and Great-spotted Woodpecker (Dendrocopus major). So I was rather amused by the appearance of the woodpecker today, as if to say, "stuff these surveys!" Maybe we'll get him for Garden Birdwatch 2011.