Sunday, 19 May 2013

Temperamental Mole

Ecological consultant Rebecca, taking water samples under the netted section of the River Mole

A tributary of the River Thames, the River Mole rises just south of Rusper village in West Sussex, flowing north-west for 50 miles (80km) before reaching the Thames at the north Surrey border.

At Gatwick our section of the River Mole is rather open and slow-flowing, passing under the airfield through a tunnel and exiting on the north side. At the southern point where it enters, a Kingfisher is regularly spotted zipping in and out.
   The course of the Mole has been altered several times since the airport began operating commercially in 1945. During a massive flood alleviation project in 1999 it was diverted once more from its course north of the airfield; now it travels west for 400m parallel to the taxiway before meandering in a north-easterly direction. With a good diversity of riffle formations, pool sequences, backwaters, lush wet grassland and reedbeds, it is in my opinion quite a lovely and natural-looking section of river.

The River Mole on Gatwick's Landholdings, north of the airfield

Vantage point from the grassy mound, overlooking the airfield - NWZ

Reedbeds in winter

The water level at Povey Cross has reached level 2 (my cunning theory is that the numbers represent 10cm, putting the water level at 1.2m.) In the past I have seen the water close to over-topping the stick.

Much of the catchment area of the Mole lies on impermeable rock, meaning that the water level responds extremely rapidly to heavy rainfall. My first week of surveying at Gatwick taught me a punitive lesson… a few of my reptile mats have probably washed up somewhere in Surrey.

Rebecca kicking the silt and netting the river-dwelling invertebrates

The water quality of the river can also fluctuate greatly depending on the season. The ecologists Rebecca and Victoria from Penny Anderson Associates regularly carry out aquatic invertebrate 'kick surveys', taking samples back to the lab for species identification under the microscope. Identifying the flora and fauna occurring in the waterways is particularly useful, as certain species are very sensitive to pollution and could act as indicators of any negative impacts of the airport's operations. On Monday they visited Gatwick and I was able to join in to see how it is done.

Damselfly nymph covered in silt - possibly a Banded Demoiselle?

Common Backswimmer (Notonecta glauca)

Diving beetle species

A small leech

Freshwater Shrimp (Gammarus pulex) is a type of amphipod crustacean

An Orb Mussel, a type of freshwater mollusc

I particularly enjoy this time of year when the Reed Warblers set up their territories all along the Mole. If you happen to wander west along the public right of way from Povey Cross you can hear their repetitive, mechanical sounding song...

I took this photo of a Reed Warbler along the Mole last summer -
 possibly my best birding photo so far!

And finally, one of the mystery coconuts which wash up regularly along the River Mole... No explanations have sufficed so far, but it gives me a hankering for lime and a tiny little umbrella.

Monday, 13 May 2013

Roving Records - Land East of the Railway Line: 10/05/13

On Friday I carried out a check of our dormouse boxes in the LERL; sadly no further evidence of their nesting activity. However the boxes are certainly being put to good use by the Blue Tits and Great Tits...

At the moment over 1/3 of the boxes contain either Blue Tit or Great Tit nests

I was crouched down while making some notes and when I looked up I don't know who was more surprised, me or this male Roe Deer...

Hazel coppice understory, a dense Bluebell carpet and a curious Roe Deer in Horleyland Wood

It wandered in a large circle around me and casually sauntered off, another male not far behind it. I must have blended in pretty well; my clothing has definitely become more 'grungy' since I first started here (whether that's a good thing or not.) I'd like to think I'm becoming a better naturalist; most recently I have acquired some collecting pots, bought a utility-belt (i.e. a bumbag) and I've mostly stopped caring about getting my feet wet.

Common Frog tadpoles in the shallows of Pond 3 (I like our exciting pond names)

I was checking the final Dormouse box when I spied this well-hidden nest between the boles (thick stems) of an old coppiced hazel, proving it to be rather useful habitat. They are likely Blackbird chicks and might have a harsh appearance just now, but their eyes are beginning to open and in a few more days their feathers will be pushing through...

Blackbird chicks in a nest

 Comma Butterfly (Polygonia c-album) in Horleyland Wood. These guys are territorial; it flew laps around me and always landed back at this spot

  (The butterfly formally known as Cabbage White) a Large White Butterfly (Pieris brassicae), over in Goat Meadow

It was a good week for butterflies as well as other invertebrates; the first Large Red Damselflies have been taking to the wing over in the North West Zone, Orange Tip and Peacock Butterflies have been busy along the River Mole, Gatwick Stream and our woodland margins. I was chuffed to get a photograph today of one of these beasties out on the move, they rarely keep still long enough to snap...

A rather conspicuous stalker...

A few days previously Scotty Dodd, Surrey Wildlife Trust's expert entomologist, visited this site with me in preparation for summer invertebrate surveys. I netted one of these and took a picture before releasing it back out. Scotty identified it as a type of Cuckoo Bee, most likely the species Nomada leucophthalma.

Potted for a close-up of this cool little wasp-like bee

No pollen-collecting bags on her back legs... this tiny sneak travels light!

Although very wasp-like in appearance with its shiny hairless abdomen, this is actually a type of bee and a 'cleptoparasite' of other solitary bees... Basically Nomada has a rather sinister lifestyle which involves following other foraging bees back to their burrow, then sneaking in to lay their own eggs on the hard-earned food supply. There were a plenty of these tiny little lurkers about, which also indicates a good size host population...
I spotted many of these tiny burrows along the edge of the path in the woodland strip - likely to be Nomada's target host

The host solitary bee in question - Andrena clarkella, eyeing me suspiciously

This little lady is what the Nomada are busy hounding - an early ground-nesting bee with the lovely name of Andrena clarkella. They are an early season solitary bee and mainly collect the pollen of willow flowers. It was great to take a moment and watch the bustling activity of all these different invertebrates, deeply engrossed in their individual missions while the good weather held out.

Brown Tree Ants (Lasius brunneus). They nest in the old deadwood of trees, probably in one of our large veteran oaks of the woodland strip

Then a bonus end to the day is finding your only pencil where you carefully left it on the footpath.

Tuesday, 7 May 2013

Great but crest-less

I've been bothering wildlife in ponds for most of my childhood but I've never come across one of these before... actually, I only saw my first Great Crested Newt early last year when another Ecologist was surveying for them at Gatwick. Last Tuesday we carried out our first G.C.N. survey of the year, the result of which was seven thumping great big females like this one.

A female Great Crested Newt (Triturus cristatus), about 14cm in length

It is slightly odd that the individuals we caught were all female as the males are generally the first to arrive at breeding ponds. Only the males have the impressive crest which runs along their backs, which I am yet to see! It may be that the relatively cold spring has confused breeding cycles somewhat, so it will be interesting to see what turns up in the next few weeks.

 Emptying the bottle traps with James Webster of EHM and ecology volunteers Katie and Kwame

The overall population trend shows these impressive fire-bellied amphibians have suffered a decline in numbers in the UK, probably due to agricultural intensification and loss of suitable habitat. That’s not to say they're not around: in fact, people have reported G.C.N. turning up in some rather interesting places including water-treatment ponds and concrete pools! However for breeding sites they tend to favour medium-sized bodies of deep water with good vegetation cover.

By taking photographs of the undersides of GCN we can identify individuals and estimate the population

 Underbelly of the beast: the plastic box and sponge doesn’t hurt them, think of it as like a damp foam-hug...

We gently hold them in place while photographing the exotically-patterned underside, creating a database of individuals. These ladies were all rather cold and sluggish so cooperated well to being handled before we released them back into the pond. We also caught some of our other two native newt species...

A female Smooth Newt (Lissotriton vulgaris) which has distinguishable spotted throat, and is around 9cm in length

A male Palmate Newt (Lissotriton helveticus), which has the indicative tail filament and webbed back feet

Female Palmate Newts, distinguishable from the female Smooth Newt by their pale pink, unspotted throats. The aquatic plant also occurring in pictures is Fat Duckweed (Lemna gibba)

We are continuing our surveys for G.C.N. over the next few weeks at the Land East of the Railway Line. All amphibians are protected by UK law and Great Crested Newts receive full protection, which means it is not permitted to capture or disturb them without a licence. You can read more about these and other UK amphibians at