Daily Archives: March 3, 2012

Local Histon Lichens

A closer look at the trees and branches, live and otherwise, in my local meadow which I posted about recently, revealed large quantities of lichen. I’d seen it there before but never really paid it sufficient attention so a couple of weekends ago I decided to rectify this shabby state of affairs.

To my highly untrained eye there didn’t seem to be more than 4-5 species but the ones that were there were present in abundance. There are four basic  morphologies of lichens: they are crustose – the flat ones which form very thin layers, foliose – form leaf like structures but where the leaves lie flat and don’t protrude far from the surface of the substrate, fruticose – have longer branched structures and can look like small shrubs and lastly squamulose –  have horizontal, scaly, overlapping lobes and look rather like some fungi I’ve seen growing on dead wood.


A grey/green crustose species and a fruticose species, the yellow one.

Lichens can be extremely sensitive to pollutants, and as a rule of thumb the foliose species are generally more sensitive and are only found in places where the environment is clean and free of fumes and other chemical pollutants. Consequently the species I find in my local patch, being close to a big town, are of the crustose and fruticose varieties. Sensitivity to pollutants can cut both ways though, those susceptible to acid pollution will obviously suffer in a low pH environment, but others which have a high demand for nitrogen can really benefit from pollution by agricultural fertilisers.

The ones I found were all growing on the surface of live deciduous trees and dead branches and the trees in the meadow are predominantly ash and oak. I’m not going to try to identify the different species here because I don’t have the requisite expert knowledge to unambiguously name lichens, but I plan to do some reading and observing and I’ll post again if I find out what they are. Even though I don’t know the species I think their colours and structures render them particularly photogenic.

The ‘thallus‘ (main body) of the yellow lichen above has the leafy structures of a fruticose species surrounding round saucer shaped structures which are called ‘apothecia‘ and are the reproductive machinery of this lichen. Within the apothecia are tiny structures called ‘paraphyses‘ and these surround the ‘asci‘ from which the fungal spores are generated. Masses of this yellow species covered many trees and fallen branches in the meadow.


Another fruticose lichen which has the leafy structures but no reproductive apothecia – I’m assuming it’s another species and not a different stage in the life cycle of the yellow one


The grey/green species here is definitely a different one. It has some erect leafy and spiky parts and it appears to have apothecia which are more cup shaped

The fungal spores produced from the asci are microspcopic and dispersed on the wind and it is a matter of conjecture how they manage to settle on the requisite species of alga to form a new lichen.

Some species can reproduce both the fungal and the algal part simultaneously by growing structures called ‘lobules‘ or ‘isidia‘ which basically consist of outgrowths of the thallus of crustose or foliose lichens which break off and are dispersed by wind and water. Or there are structures calles ‘soredia‘ which are algal cells enmeshed in a bundle of fungal ‘hyphae‘ (threadlike structures of fungal cells) which are similar to the middle part of the body, the ‘medulla‘.

If anyone out there knows the names of these lichens or has any other snippets of lichen related information please leave a comment as I’d be very interested to hear them.

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A stroll through the Meadow

Last Sunday I spent a glorious couple of hours in the piece of scrub near my house where me and the dog while away significant chunks of our time. He chases rabbits, cats, pheasants and generally enjoys doing what dogs do, and I marvel at all the wildlife to be found in my local bit of wilderness. It’s probably about 300m x 150m and it’s called ‘Rowleys Meadow’ even though it’s not a meadow, and it lies on the northern edge of the village with houses lining it’s southern periphery. On the east, west and north side are old hedgerows and some wonderful old trees and in the middle are stands of young ash trees, grassy areas and large clumps of brambles.

It plays host to an astonishing variety of wildlife which in the winter and early spring is mainly birds, although a peacock butterfly fluttered by last Sunday and on several warmer days since Christmas I’ve seen bumble bees flying around there . But on this particular day it was the birds that stole the show (click here for a full list of all my sightings on this outing on February 26th).

There are very healthy numbers of green woodpecker here due to the trees and the grassland where they can find there favourite food of ant and termites. They’re tricky to photograph in the Meadow because they’re hidden in the grass and they’re very skittish, so it’s difficult to get close enough when they’re on the ground or in the trees.

Green woodpecker with his black eyepatch and scarlet military policemans cap. This one did let me get close enough… just

There are regularly 5-10 green woodpeckers (Picus viridis, Dansk: grønspætte) to be found as I circumnavigate the Meadow. It’s easy to spot them, both the colours and the low bouncing flight, often no more than 15 feet from the ground, are very distinctive. And of course it’s call is like no other creature, if you’ve never heard it listen here. Scroll down to the entry from Lars Krogh from Lindet Skov in Denmark dated 19/04/2011 where there is a very good recording of a male greenie yaffling and drumming.

Another bird which I almost always see in the Meadow is the long tailed tit (Aegithalos caudatus, Dansk: halemajse). But for the tail, they’re tiny: the adults weigh 7-8g with a wingspan of 18cm. The long tailed tit is one of those creatures that make we wonder how such tiny ones can survive a long freezing winter. They can also be very difficult to photograph as they never stay still for more than a few seconds.


On final approach…

But when you are lucky enough to capture them they make delightful pictures!


Touchdown!

You may have noticed the lichens on the branches, I’ll share some photographs of those in the next post. In another tree adjacent to the one with the long tailed tits was a pair of great tits (Parus major, Dansk: sortemejse), among others. I like great tits, they’re handsome birds and they’re entertaining to watch feeding in my garden, especially when there is a family of them. The pair here are a male and a female:

Male great tit, his black stripe stretches all the way across his chest from toe to toe, making him very desirable indeed. I think the ‘A’ indicates he is the alpha male

The stripe of the female is much narrower:


Great tit female

And very shortly after I took the pictures of the great tits, a female sparrowhawk circled slowly overhead. The trees and hedges suddenly went very quiet as all the small birds concealed themselves from this fearsome predator. I’m not sure if she was hunting as I spotted a second, possibly a male, sparrowhawk circling much higher up. She was probably not more than a hundred feet up, but the male was several hundred feet up. I watched a pair of sparrowhawks do this over my garden once before, where the male was much higher, and I think it may be part of the courtship routine. (If anyone can confirm or refute that please drop me a line and let me know).


A female sparrowhawk circling over the hedges at the north end of the Meadow

All in all it was a very enjoyable and rewarding trip in bright warm sunshine and the  birdlife was there in spades.

All quiet on the Histon Front

Last weekend I posted about the blackbird war that was taking place in my garden on Saturday morning. By Sunday things appeared to be quiet first thing until two female blackbirds appeared and commenced battling for breeding rights.


One of the feisty females scanning her territory for possible competition

The females chased each other round for about half an hour when who should show up…


Blacktip

Hard on the heels of Blacktip came The Arch Rival, and as soon as the females established their pecking order, battle commenced. At the close of hostilities on Saturday the apparent winner was Blacktip but on Sunday the female appeared to have switched her allegiance and teamed up with The Arch Rival and both of them now joined forces to chase off Blacktip:


The Arch Rival gaining the upper hand


And Blacktip making a tactical withdrawal after some protracted aerial exchanges and succumbing to numerical advantage

Things cooled off considerably after Sunday but minor skirmishes took place until Tuesday with The Arch Rival and his moll the seeming victors. But ever since then the garden has been frequented by various blackbirds including Blacktip. So even if he lost the insemination rights he has still retained access to his feeding territory.

Fascinating stuff!