Thursday, 31 October 2019

Spiders and Bats

October 2019 has been a fine month for watching the diversity of wildlife along the river, conditions changing from day to day. Our temperate climate here allows for frequent changes which other countries don't have. A continental climate means summer is summer and winter is winter, with predictable weather most of the time, although climate change may be affecting this. 
Rivers flowing through a landscape can have a very local effect and provide habitat for more species of wildlife than other regions. 
Insects are a key to this. What have spiders and bats in common? They prey on insects which are very often most numerous in riverine environments. Spiders and bats often go unnoticed until conditions change, and their presence becomes more visible:


A spiders web on a misty morning 22nd October 2019
This web was laden with water-droplets, until they evaporated in the sun.



Another web on the same morning quite close to the ground
and the river bank.

Bats forage when light-levels are low, spending the daylight hours roosting in darkness hidden away unnoticed by creatures which might otherwise prey on them.
Here the huge old oaks along the river provide excellent roosts, with old branches providing cavities in the bark where there is space for bats to squeeze in and hang onto the rough surfaces. 


 An old oak on the edge of the river at the end of an important bat flyway.
As soon as light levels fall, bats fly out of their roosts mostly in old oaks 
some distance from the river and make their way along a hedge
and trees down to the old oak where they immediately start to catch aerial
insects over the river surface and in the trees above. They move on along the river, catching insects as they go, as the vegetation on the banks forms a directional guide for them to follow. When they have finished for the night they usually follow the same route back to their day roosts. They do not fly in strong winds or driving rain, so mature vegetation and trees provide shelter and enable them to continue foraging.






Saturday, 5 October 2019

Fruitful September

September 2019 was warm with summer clinging on but an increase in showers, all good for ripening fruits and berries.
Friday 27th September was a typical day, mild with frequent sudden light showers coming in with the southerly breeze. The ground was scattered with acorns crunching underfoot and oaks still laden with many more, both green and ripening brown shells. The river was running well after a sudden high surge and then dip in the level the previous week - due not to the weather but to the necessity of having to temporarily empty the Mill pond upstream in order to facilitate repairs to piping at the mill and giving a chance to restore the Tern platforms on the pond before the winter. This all happened very quickly and it was soon back to normal with no loss of aquatic wildlife.

Along the river on the day of the survey clouds brought in short-lived showers between warm and sunny spells and it was interesting to note how wildlife reacted. As dark clouds approached, bird activity increased - as they sensed the rain, they made direct flights to the nearest dense trees to shelter with no procrastination such as stopping in mid flight to forage on berries or insects. I did the same, choosing to stand under the shelter of the nearest old oak tree, the ground underneath remaining quite dry. There were good opportunities to observe from across the grass, through the rain, or turn to a hedge with sheltering robins and dunnocks.  


This Comma butterfly was about to open its wings and bask on the Bramble leaf to soak up the sun.
When the wings are closed it's almost invisible when amongst autumn leaves, but its signature - the white marking shaped like a comma, gives it away. The white comma visible here looks as if it's painted on but this is just how we see it, given a good view. This one is an overwintering Comma, a dark form which will very soon find a place where it will hibernate during the winter and wake us up to the Spring when we see it appear on the banks as early as March. During the summer the eggs are laid on fresh Nettle tips which the caterpillars eat when hatched -  like many of our butterflies the caterpillars need Nettles as a food source. If you get rid of the Nettles you destroy most of the butterfly population!

A Red Admiral was seen basking in the sun on some fallen leaves, two Small Copper butterflies were erratically flying along a sunny bank and numerous Speckled Wood butterflies were chasing and basking in the sun, high and low amongst the trees.
 Insects were always the first to emerge as soon as the rain cleared and the sun warmed up the leaves. Over the river banks, bees, flies and wasp species could be seen buzzing around wild flowers and seed heads, butterflies too.


Amongst the grass - a very small Cricket (centre)
This is probably a short-winged Conehead with
long antennae - although foreshortened in this photo.

Strong-flying dragonflies, the Southern Hawkers were still numerous over and away from the river.
Two Common Darters were perching on twigs in a sheltered and sunny area.
Numerous spiders had been at work, spinning webs across brown grass seed heads and thistle tops which had been very successful in trapping many small insects.

House sparrows were seen and heard amongst their traditional hedgerows, dropping down to shelter when it rained, continuing to sing (about 50). Robins (22) were more numerous now, with many singing territorial songs which they will continue to sing throughout the winter months. Blackbirds and thrushes were keeping a low profile with only seven blackbirds and one song thrush seen today.
October should see them appear in new 'winter' plumage.


Elderberries ripenin

Blue tits (45) were out foraging for insects as soon as the rain stopped whilst Great tits (25) continued to forage lower amongst the dry understory and roots with wrens (8) some singing, and dunnocks (3) all sheltered by the still-green leafy tree roots and ivies. Long-tailed tits (5) were seen in the Willow canopies in the sun. As usual, nuthatches were seen and heard amongst the huge strong oak branches (4),  juveniles now seeking out their first nest sites with older nuthatches guarding the nest holes they have traditionally used. They will also be caching nuts. A tap-tapping sound will be heard when Nuthatches are shelling nuts, usually wedged in a branch twig. A single treecreeper flew up and out of an old oak when a nearby nuthatch called. Great-spotted woodpeckers have had a good summer rearing young and several have been seen with adults. Today three were seen, one climbing the trunk of an Ash tree, gleaning insects, another was calling from an oak and another was seen flying across from oak to oak. Three goldcrests were also seen in the oaks, making fine contact calls, their conifers not providing such good shelter as the oaks still in leaf.
Goldfinches (25) were numerous but in scattered groups in thickets sheltering from the rain, not singing as much as usual. Their favoured food being dry seeds from Dock, Thistles and grasses, dry weather suits them better, as with other finches. No greenfinches or chaffinches were seen. 
Only one blackcap was heard but three chiffchaffs were present in willows nearby, moving fast.

 About thirty wood pigeons were present today, most quietly feeding on the ground under the trees. Six jackdaws were seen flying out of the woods and nine magpies in various places, not seeking shelter from the rain. Herring gulls, making the most of the breezy weather were fling across (10 or more), with five starlings and fifteen carrion crows.

A fine finish was the sighting of at least forty house martins flying together with about seven barn swallows over the river, catching insects for some time. Suddenly a sparrowhawk appeared from nowhere and flew amongst the group. They seemed quite fearless approaching it rather than flying away; the sparrowhawk was unlucky and quickly flew off.