Week 28: Hemel Hempstead Barn Owls

Southern Hawker dragonfly, Bovingdon Brickworks (perched after hunting by the Buddleja)

Southern Hawker, Brickworks

Bramble blackberries, Brickworks

After fledgling Wagtails and nestling Swallows; riverside damsels and hunting dragonflies; meadows of moths and butterflies, I hadn’t got a clue what wildlife wonder I might encounter this week. In my wildest dreams, I don’t think I could have conjured up what transpired.

After months of not feeling up to going out beyond about 6pm, the sunset on Monday evening, combined with improved health, tipped the balance. Box Moor Trust land set against a fiery sky, seemed like a good plan. Of course, the inevitable happened. By the time I got out of the car, the colours had faded and the moment had passed. Still, it seemed a pity to waste escaping the house and so off I set. I debated whether or not to bother with the tripod but decided that if I left it in the car, I was bound to regret it.

I might have missed the sunset but I came across something far more exciting. Over the past month or so, there have been a number of Barn Owl sightings around Hemel Hempstead. On the Box Moor Trust Moth, Bat and Glow Worm evening (27th June), the group had enjoyed watching a bird quartering over the field between Chaulden Lane and the railway bridge. Dan Forder (of Hemel Birding fame) had seen a bird near the M1 Jun 8 on 7th July. And, on Monday evening, as I walked over Trust land, I chanced upon one of these beautiful creatures perched in a tree. It eventually took flight, soared silently over my head and away. Utterly magical and boy was I glad I had the tripod with me! The light was almost gone but I was able to get some ropey video footage before darkness fell. Special thanks to my talented Sister, her choir and the Robin soloist(!) for the backing track. A couple of years ago, on a sultry summer evening, the choir threw open the hall doors as they sang a cappella. Nature joined in. The resulting piece is candid and unique. A male Robin sings his evening song and the choir swells to accompany him.



Having done a little reading about Barn Owls, it seems to me that the females have the right idea. Grab yourself a monogamous mate and sit around all evening whilst he goes off and finds the food. Once eggs are laid, snuggle up inside the nest site, don't bother to build a nest (who needs twigs when regurgitated pellets will do?!), don’t bother to wash, and lap up meals-on-tap from the doting male. Result!

Ten Barn Owl Facts, shamelessly copied and pasted from the internet (with a few minor additions). More facts here.

1. The barn owl was voted Britain’s favourite farmland bird by the public in an RSPB poll in July 2007. 
2. Historically, the barn owl was Britain’s most common owl species, but today only one farm in about 75 can boast a barn owl nest.
3. Barn owls screech, not hoot (that’s Tawny owls). 
4. The barn owl can fly almost silently. This enables it to hear the slightest sounds made by its rodent prey hidden in deep vegetation while it’s flying up to three metres overhead.
5. The barn owl’s heart-shaped face collects sound in the same way as human ears. Its ears are placed asymmetrically for improved detection of sound position and distance, and it does not require sight to hunt. Its hearing is the most sensitive of any creature tested.
6. Barn owls are non-territorial. Adults live in overlapping home ranges, each one covering approximately 5,000 hectares. That’s a staggering 12,500 acres or 7,100 football pitches!
7. It’s not uncommon for barn owl chicks in the nest to feed each other. This behaviour is incredibly rare in birds.
8. In order to live and breed, a pair of barn owls needs to eat around 5,000 prey items a year. These are mainly field voles, wood mice, and common shrews. One of the most unusual feeding records is of a barn owl catching flying hawk moths.
9. Though barn owls are capable of producing three broods of five to seven young each year, most breed only once and produce, on average, only two and a half young. 29 per cent of nests produce no young at all.
10. 91 per cent of barn owls post-mortemed were found to contain rat poison. Some owls die as a direct result of consuming rodenticides, but most contain sub-lethal doses. The effects of this remain unknown.

Barn Owls are a Schedule 1 protected species. It’s fantastic that there appears to be a number of birds locally.


Finally, this week's oak...

And, Dellfield in Summer...

It seems incredible that just 3 months ago, this meadow was carpeted in Cowslips…

Week 24: A Novel Use of Nettles & Family Wagtail

The first week of July and yet, applying my mind is like trying to rouse a tiny dormouse, snuggled up in a downy nest, seeing out the winter. That is to say, the creative juices have run dry. I’m adopting the less is more approach when it comes to words and will perhaps rethink things from week 26 onwards. By that point, the project will have been going for 6 months and might be worth tweaking/reworking/abandoning. Who knows.

Ok, first up, it’s a female Banded Demoiselle.

This one was fluttering around the common nettles by the river, east of Station Road on Harding's Moor. At one point it looked as though it was ovipositing some 15 metres from the river (pardon?!). That had me scratching my head until someone suggested that perhaps the Demoiselle was using the bristles on the nettle leaf to clean itself. That made perfect sense, especially when I noticed that apart from the mating claspers (cerci) and ovipositing appendages (stylus), the damselfly had a foreign object hanging from its rear end (nice!)!

After the Broad-bodied Chasers, I’ve seen an additional 3 species of dragonfly this week on Trust land. A few Emperors (river Bulbourne, Gadespring cress beds and Preston Hill pond), a Southern Hawker around Fishery Moor and a Common Darter (photographed, left) at the Preston Hill pond.

Most noticeable this week, though, has been the number and variety of butterflies out and about. Marbled Whites, Commas, Small Tortoiseshell, Meadow Browns, Ringlets, Red Admiral and Small Whites to name but a few. Add to that, Small and Large Skippers out in good numbers now. I have attempted a Skipper ID comparison (below) from photographs taken at the Brickworks this week.

Small Skipper (Thymelicus sylvestris) (left); Large Skipper (Ochlodes sylvanus) (right)

3 Key Differences

1. Size (wingspan): Small Skipper 27-34mm; Large Skipper (male) 29-34mm, (female) 31-36mm. Their wingspans overlap but the Small Skipper is noticeably smaller in the field.
2. Shading on the wing: Large Skipper - dark shading/patterning on forewing
3. Antennae: Small Skipper - orange/brown rounded tips; Large Skipper - hooked tips. I’ve not found an Essex Skipper (yet) so don’t have to worry about that!

Up on Further Roughdown, I came across a pair of mating Ringlets (Aphantopus hyperantus). Their larval foodplants are grasses [Cock's-foot (Dactylis glomerata), Common Couch (Elytrigia repens), False Brome (Brachypodium sylvaticum), Meadow-grasses (various) (Poa spp.) and Tufted Hair-grass (Deschampsia cespitosa)].

And, near Old Fishery Lane, a Gatekeeper butterfly (Pyronia tithonus) was warming itself, perched on nettles. This is another species that relies on grasses as larval foodplants [Bents (various) (Agrostis spp.), Fescues (various) (Festuca spp.) and Meadow-grasses (various) (Poa spp.). Common Couch (Elytrigia repens)].

Early on in the week, Monday, I think it was, I was walking across Station Moor when I suddenly heard the distressed calls of a Grey Wagtail. I looked up to see a Sparrowhawk lazily flying south, carrying something in its talons. The diminutive Grey Wagtail was in hot pursuit as if its yellow go-faster-stripes were sufficient protection against such a predator. I did wonder if the Sparrowhawk had made off with a young Grey Wagtail. Anyway, on Thursday, I was able to get back to the area and was pleased to discover that, whatever had been going on with the Sparrowhawk, it had not prevented the Grey Wagtail pair from successfully fledging at least 2 youngsters this week by the Fishery Road canal bridge. I’ve put together some video footage of the parents and one of the fledglings. It was a task and a half to capture significant moments when the wind wasn’t gusting and making the footage unusable. Some clips are a little ropey (to put it mildly!) but hopefully that doesn’t detract too much from enjoying the events.



Finally, this week's Oak photograph.

Week 20, Surprises: The Skipper & The Tortoise

It really doesn’t have the same ring to it as “The Hare and the Tortoise” does it, but I didn’t want to get you here under false pretences. A few nice surprises yesterday, which deserve a mention, mean a hurried Sunday evening post is in order.

Saturday, I braced myself for torrential rain, thunder, lightening, and the apocalypse. However, by midday, all the drama had passed and it was warm, dry and sunny. I headed to Dellfield early evening as there is a particular scene I want to photograph. More on that another time, though. Anyway, as I climbed the path through Dellfield, a bug flew in front of me and landed in the grass to my right. Taking a closer look, it was a Common Green Shieldbug (Palomena prasina) (of week 16 fame) but what was more exciting was the Tortoise Beetle on leaves just behind it. This is another invertebrate group (or genus, the Cassida genus, to be precise) that Martin Parr introduced to me. There doesn’t seem to be a great deal of specific information about them on the internet but, as far as I can make out, they feed on the surface of leaves (specific plants for specific species) and, like tortoises, when threatened, they can pull in there antennae and legs and drop their dome-like carapace so that it is flush with the leaf. Great camouflage and good protection. 

From what I’ve read, determining species can be quite difficult, even with a photograph. However, it’s likely that the Tortoise Beetle I found yesterday was Cassida vibex, which feeds mainly on Thistles and Knapweeds. It seems to have a south-easterly UK distribution (rare or scarce beyond this region). And, it’s another tiny little creature, just 7mm long. (….Oh, ignore the Large Skipper for the moment)

Tortoise Beetle (Cassida vibex)

Large Skipper (Ochlodes sylvanus)

My first encounter with a Tortoise Beetle was last month at the Brickworks. I had joined Martin for an afternoon of surveying and he came across what we later identified as a Thistle Tortoise Beetle (Cassida rubiginosa) (not to be confused with the thistle eating Cassida vibex!). The rusty brown “triangle” at the front of the wing cases distinguishes it from the Green Tortoise Beetle (Cassida viridis).

     Thistle Tortoise Beetle (Cassida rubiginosa) [16 May 2014]

The “rubiginosa” of its name “refers to the beetle's ability to produce a red liquid from [its] head”! I’m not sure I fancy seeing that but good to know if it happens in the field and you’re after an ID! This species feeds on Creeping Thistle (Cirsium arvense) and, according to NatureSpot, “has the most interesting larvae and pupae. The larvae have twin tail-spikes and these are sometimes used to carry dead skins and droppings in a kind of parasol [nice!]. The spikes are retained by the pupa and these are flicked forward if it is disturbed.” Weird eh! So, there were are. A whirl-wind introduction to the genus Cassida, the Tortoise Beetles. Hopefully, I’ll come across a few more over the coming months.

Obviously, the other colourful find yesterday was a Large Skipper butterfly (Ochlodes sylvanus) (actually there were two) on Bovingdon Reach. And, on the pond on Preston Hill, I watched 3 male Broad-bodied Chasers achieving olympic standard “chasing” around the water. One, with a broken wing, eventually perched on a twig close by, giving me a chance for photographs (below). Finally, as I was walking from the pond towards Hay Wood, I heard the most peculiar sound. A friend had recently described to me the “call” of a female Cuckoo and, I can only conclude that that is what I heard. It was a kind of subdued, hallow, rich random burbling, coming from the tree tops. Unfortunately, it was too distant for the mic on my camera to register otherwise I would have recorded it. Ultimately, the source will remain a mystery but it would be nice to think that a female Cuckoo is around and the species has bred this year in Hay Wood.

Week 18: The Butterfly Effect

There has been an awful lot to catch my eye, spark my interest and tickle my fancy this week! I’m quite glad of the forecast rain today. It gives me the opportunity to put together a post.

The butterfly effect. Going to sleep last night, the lasting vision, burned into my retinas, was that of a tiny butterfly, on the top of a flower, blowing gently in the breeze. Unfortunately, in the field, that vision is all too often accompanied by mild impatience and the taste of helplessness (please let this little creature stay put), with anticipation that said flower might finally come to rest, allowing the chance to take a shot. It may not be chaos theory but, capturing the moment is downright tricky, especially if a butterfly decides to flap its wings.

When it comes to photographing these lovely insects, I am a novice. It seems to involve a heck of a lot of patience and luck. I have been pursuing Orange-tips all spring, without success. This week, it was the Small Coppers that led me on a merry dance (quite literally) around Dellfield and Bovingdon Brickworks. I dread to think what I looked like to passing dog-walkers, as I ran around in circles, weaving this way and that, following tiny (invisible?!) flying objects! However, when you do come across a butterfly, or group of butterflies, which are inclined to settle in one spot, it is pure heaven. Such was my good fortune on Tuesday afternoon.

The main meadow at Bovingdon Brickworks (the one with the mound of earth in the centre) held at least 7 Common Blue butterflies, all in one small area. This meadow, and the one to the north-west of it, are covered in Bird’s-foot Trefoil, the favoured nectar plant of the adults and the primary foodplant for the larvae. Through the afternoon, the sun was hidden behind clouds, which meant the butterflies were less energetic. In what felt like the blink of an eye, I had whiled away an hour in the company of predominantly settled Common Blues. I had the opportunity to photograph both male and female and to gain upper and underwing shots.

Common Blues (almost a mating pair, female, left; male, right) on Ragged Robin (Lychnis flos-cuculi)

Male upperwing

Female upperwing

Male underwing

Female underwing

[If you’d like to see higher resolution images of the Common Blues, they are in a set on Flickr, here]

The good weather carried on into Wednesday so I decided to return to the Brickworks. I’d seen a Small Copper the previous day and hoped to relocate it. However, before I even arrived at the meadow’s entrance gate, in an area of dappled shade, I came upon a duelling pair of male Speckled Woods. I watched them tussling in flight until the interloper eventually capitulated and flew off. The victor quickly took up his favoured, sunlit spot in the nettles to wait for passing females. As for the Small Copper, I did eventually find one at the Brickworks but only managed a record shot. In the afternoon, I thought I’d try my luck at Dellfield and when I’d finally given up and was heading home, I stumbled upon a settled Small Copper. It absolutely made my day.

Speckled Wood (Pararge aegeria)

Small Copper (Lycaena phlaeas)

Butterflies weren’t the only insects on the wing this week. Whilst trying and failing with the Small Copper at Dellfield, I came across my first migrant moth, a Silver Y (Autographa gamma). The “Y” refers to the prominent creamy/white marking on each wing resembling a “Y” or the greek letter “gamma”. There were also a couple of Grass Rivulet moths (Perizoma albulata) and numerous Burnet Companions out around Dellfield (where there’s plenty of Red Clover (larval food plant)). There was also a Cinnabar moth and 2 or 3 Burnet Companions out at the Brickworks (the Bird’s-foot Trefoil being another preferred larval food plant for the Companion).

[Dellfield] Silver Y moth (Autographa gamma)  [For a higher resolution, see Flickr image]

[Brickworks] Cinnabar moth (Tyria jacobaeae)

[Brickworks] Burnet Companion moth (Euclidia glyphica)

A couple of other fun finds at the Brickworks were a Broad-bodied Chaser dragonfly and the aptly named Swollen-thighed Beetle. The Chaser took me completely by surprise (I was nowhere near a pond!) and I only managed 2 photographs, from a distance, with the wrong lens, before I lost it again. The Beetle was feasting on the buttercup pollen and it's the massive thighs which indicate gender.

Broad-bodied Chaser (Libellula depressa) (female)

Swollen-thighed Beetle (Oedemera nobilis) (male)

Birds of note at the Brickworks on Wednesday morning were a singing male Cuckoo, a couple of Bullfinches (a male flew over my head) and a Nuthatch in the woods by Shantock Hall Lane. I also came across a ragged looking female Whitethroat, perhaps busy raising a brood. The Common Frog spawn seems to have disappeared from the flooded gully so I shall stop reporting on that.

Ben and the team ran the moth traps this week at the Brickworks and Gadespring. They attracted more than 100 species, staying up into the early hours of the morning! That’s what I call dedication! You can read the full report on Ben’s blog here.

If you’ve not had a chance yet to vote in the readership poll, in the previous post, there's still time. It would be much appreciated. Thank you.

Finally, this week’s Oak photograph. What a difference a few leaves makes!

Left, 23 January 2014; Right, 19 May 2014