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February Nature Notes

The secret life of mosses

When the larger organisms are active they hide the shy and secretive ones, but if you look carefully at a clod of bare soil, which has lain undisturbed through the winter you may be able to see a slight green sheen across its surface. This is caused by a growth of branched and interlacing threads called a moss protonema. This little mat is so fine that you will find it difficult to see any of the single threads (unless you can use a strong hand lens or a microscope) since they are only one cell thick. 

              moss protonema   protonema on soil

As the protonema grows small multicelled buds are produced and from them the short upright leafy shoots of the moss develop, making a tight little clump we all know. Keeping the clump under observation, you may be able to see what look like small green flowers at the tip of the branches. These little cups contain the sexual parts, some ‘flowers’ contain antheridia which make sperms while some (usually more tightly folded – and therefore more difficult to spot) hold oogonia which contain eggs. The moisture of spring allows the sperm to swim and fertilise the egg, to produce the new generation.
                                           anthridial cups  
The surprise is that the fertilised eggs do not form a new protonema but something altogether different. The egg grows in place, getting nutrition from the parent plant, and develops into an elaborate structure consisting of a foot (embedded in the parent plant), a stalk (seta) and a head (the capsule).

      capsules closeup peristome


The capsule has a complicated internal structure and an elaborate cap (surrounded by an orange ring in this case). If the cap is removed or when it falls off once the capsule is mature, the peristome teeth underneath it are exposed. These are sensitive to humidity changes, opening to release the spores when conditions are suitable. Some capsules seem to have a ‘beak’; this is the remains of the female structure that has been carried up on top of the capsule as the seta elongated. The spores germinate to produce a new protonema.

                                                      spores germinating

Mosses are most active when there is still plenty of moisture around, so early spring is a good time to look for them. Different mosses can be found in different habitats; before the vegetation grows up we can find the different species, on the base of tree trunks, on the verges, around the burn sites of old bonfires. Careful comparisons of the leaf shapes will soon show you different varieties. Have a look to see how many species you can find and see if any are producing their sexual stage or their capsules.

If you go to the British Bryological Society website at www.bbsfieldguide.org.uk you can find a key for the identification of mosses. It says' log in' but that isn't necessary and under 'Keys' you can click 'General Field Key' which gives access to a botanical indentification key. At the moment it can even be printed off for use.

Grey Squirrels

It is a sobering thought that the people who built the Nickey Line would have known what a squirrel was, but they would be thinking of what we now call the red squirrel. The grey squirrel as its Latin name (Sciurus carolinensis) suggests was introduced from America. A debate has been going on as to whether the decline of our red squirrel population is simply down to competition from the grey. Certainly the grey has played some part in the elimination of the native red squirrel over most of England and Wales, if only because they carry a virus which is more lethal to the red. It is ironic that the wild mammal easiest to see is one that does not belong here. There are of course other mammals along the line, rabbits, hares, foxes and hedgehogs can be seen. There are badger setts and although you will be lucky to see them, muntjac deer can be found moving through the area. They too are an introduction. Smaller mammals like stoats, mice, voles and shrews are also there but rarely spotted.


Bird song

Saint Valentine's Day falls in mid-February and was thought to be the day when birds chose their mates. Many birds begin to sing much earlier. Male chaffinches sing now to claim a territory. Their chests are a rich pink and their caps a strong blue. The song, which begins slowly, increases in speed and ends in a final flourish, will need practice before it is perfected. Later in the month rehearsal will have paid off and they will be note perfect. Blackbirds are beginning to sing and wrens, generally silent during the winter, start to call for a mate. They have an incredibly strong song for such a small bird.


One of the delights open to us is a short diversion from the Nickey line into the fields between Harpenden and Rothamsted Farm. A public footpath passes through the open fields and even in February if you walk out on a sunny day the skylarks will be climbing up into the blue full of song. If you go to the website www.rsbp.org.uk/skylark , and then take the audio button you can play the song for yourself and why not learn the song of the male chaffinch while you are at it!

                                                       skylark

It is worth putting the effort in now to familiarise oneself with the songs of some of our local summer visitors prior to their arrival. It may surprise you to know bird recorders will identify more of our song birds by their calls and songs than by sight. The British Trust for Ornithology (the BTO) has an excellent library of images, videos, calls and songs which can be found by going to their website www.bto.org , selecting ‘About Birds’, and then entering the bird of interest in the search the box ‘Search for a Species on BirdFacts’ This provides a lot of scientific detail on the bird you have entered, and under a section titled ‘Identification Tips’ images, videos and sounds of the bird. The BTO ‘About Birds’ webpage also has a collection of over 50 videos to help one distinguish between birds which might be confused, which can be accessed from ‘bird ID workshops‘.

 

 

August Nature Notes

September Nature Notes

October Nature Notes

November Nature Notes

December Nature Notes

Wildlife Interpretation Board
Progress on our new Wildlife Interpretation Board

Fungal Foray Wednesday 22 October 2008

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