Saturday, February 25, 2017

Feeding frenzy

When we were walking along Whitburn beach in Sunderland this afternoon I noticed a dense flock of about 150 black-headed gulls on the tide line and as we got closer I could see ....

... that they were all picking something off the sand, in a real feeding frenzy.

A closer look revealed many thousands of these tiny white maggots washed in by the incoming tide.

Here they are - the larvae of the seaweed fly Coelopa frigida.

About a week ago we had a spell of warm weather that must have been perfect for these flies to breed in the big piles of kelps and wracks that form natural compost heaps on the beach.

Then two days ago Storm Doris arrived, creating mountainous waves that would have washed the rotting kelps and the fly larvae into the sea.

Today the tide brought them back in again in enormous numbers on this short stretch of beach, providing a fantastic feeding opportunity for the gulls and also for waders like turnstones, sanderlings and redshanks.

As the old saying goes, 'it's an ill wind that blows nobody any good'.

Tuesday, February 14, 2017

Picture-winged fly Urophora jaceana

In late summer little insects called picture-winged flies lay their eggs in the inflorescences of knapweed  and ...

... when they hatch the larvae crawl down into the  seed head, feeding on the seeds and producing a woody gall that persists through the winter. You can tell they are there just by squeezing the seed head, when you can feel the hard gall within.

Here is a seed head carefully cut open, to reveal the larvae in their woody chamber within...

.... including this one that looks well fed and ready to pupate. 

I harvested some galled seed heads back in November and today the adult insects began to emerge.

The tiny flies have rather beautiful eyes but....

 ... their most striking feature is their wing patterns that give them their common name.

I think this species is Urophora jaceana - thanks to @SK53onOSM for correct ID

Update: Geoffrey Wilkinson (see comment below) informs me that this species is Chaetostomella cylindrica

Thursday, February 9, 2017

Book Review: Built on an Ancient Sea

I don't often review books on this blog but this one is rather special, because it tells the 300 million year-old story underlying the landscape and natural history that I often write about.

Built on an Ancient Sea: The Magnesian Limestone Landscapes of North East England by John Durkin, Niall Hammond, Elizabeth Pickett and Paul Williams. Published by Groundwork NE & Cumbria. ISBN 978-0-9935039-0-0. £10.

The landscapes of East Durham’s Magnesian limestone hold a special place in the affections of anyone with a passion for the natural history of our region. Sites of Special Scientific Interest, National Nature Reserves and several of Durham Wildlife Trust’s finest nature reserves owe their existence to this distinctive underlying sedimentary rock. The summer display of wild flowers in its species-rich grassland can stop a walker in their tracks, whilst its cliffs of warm, honey-coloured rock provide some of our most spectacular coastal scenery.

Built on an Ancient Sea is a book that will help readers look on this much-loved landscape through fresh eyes. In eight chapters it takes us on a 300 million year journey from the warm, equatorial seas where our limestone was laid down, through the great Ice Ages that sculpted our landscape, then on past the first human colonisation to the present day, where we have transformed the natural landscape for our own purposes.

All too often the geological processes that create landscapes are overlooked by naturalists, perhaps because so much lies out of sight, perhaps because of the unimaginable timescales involved. One of the great achievements of the authors is that they vividly portray just how much the scenic beauty, history and natural history of our region owe to what lies deep beneath our feet.

Ever since the glaciers retreated and we humans first settled here, the underlying rock strata have played a major role in where we settled and how we lived. Geology ultimately determined the natural resources that were locally available and the location of ports that became lifelines for trade once the land bridge with the continent sank below the North Sea. Limestone supplied the raw material for buildings, agricultural lime for soil improvement and, from within adjacent strata, coal and minerals that have dominated our recent industrial history.

The authors have done a wonderful job in drawing together all the threads of geology, human occupation and natural history in this lavishly illustrated book. In a forward-looking, thought provoking final chapter they highlight the way in which the Magnesian limestone landscape is still evolving under human influence.

Built on an Ancient Sea is part of the Limestone Landscapes Project, supported by the Heritage Lottery Fund, which has done so much to raise awareness of the special importance of the Magnesian Limestone landscape in the North East. Read the book then visit the twenty two key locations it recommends; even if they are already familiar, you will see them in a new light.

Tuesday, February 7, 2017

Rambling brambles

There is something very stealthy about the way that brambles move around. The shoot in the photo above has used its prickles to grip the far side of the mossy wall, then extended its growth until it reached the top of the six foot barrier and is now undulating along this side of the wall. 

Eventually that long shoot will bend under its own weight, towards the ground....

..... and when it touches the soil this will happen - adventitious roots will form.

Now, securely anchored and with an additional supply of mineral nutrients and water, a new, long, arching shoot is beginning to form and soon the whole process will begin again. Constantly conquering new territories, bounding across the landscape.