About Dom

Digital producer and wildlife photographer

Fly orchid pollinator

The fly orchid (Ophrys insectifera) is usually found on chalk and limestone soils in open deciduous woodland and scrub, but is also recorded from grassland and chalk-pits. It is rare in the UK and even at known locations can be difficult to spot.

Fly orchids

Fly orchids in woodland clearing. Surrey, UK.

Fly orchids are in flower between May and June. At this time they attract male digger wasps (Argogorytes mystaceus) with a scent which closely resembles the female wasp’s pheromone.

Males attempt to copulate with the orchid and during this process pollinia become attached, which may be carried to the stigma of another flower, completing pollination.

Digger wasp pseudo-copulating with fly orchid

Digger wasp attracted to fly orchid flower.

Male digger wasp pseudo-copulating with fly orchid

Male digger wasp pseudo-copulating with fly orchid.

Digger wasp with fly orchid pollinia

Fly orchid pollinia attached to the head of male digger wasp.

I was finally lucky enough to observe and document this behaviour in the Surrey Hills earlier this year.

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Case study: Butterfly Conservation

Working for the local branch of Butterfly Conservation I developed an online system to document sightings of butterflies submitted by members of the public in Dorset.

This ‘citizen science’ project encourages engagement in nature conservation and adds to our knowledge of these vital environmental indicator species.

In 2018 more than 44,000 butterflies were successfully recorded using this method.

Capture

Initially butterfly spotters are directed to a web form which collects personal info, location details including grid reference, and species observed.

Butterfly recording form

Butterfly recording form

Butterfly recording form

Butterfly recording form

This information is then inserted into the Dorset Branch web sightings database.

Verify

Expert verifiers are given password-protected access to a record management interface on the branch website. Recently submitted butterfly sightings can be reviewed and verified with a single click.

Butterfly records management system

Butterfly record verification

Questionable records can be studied in more detail and recorders contacted to clarify information as necessary.

Butterfly records management system

Butterfly record management view

Interpret

Verified records are instantly published to the branch website, using a number of graphical representations for easy interpretation.

Butterfly data: map

Butterfly data: map

Butterfly data: tree chart

Butterfly data: tree chart

Butterfly data: calendar

Butterfly data: calendar

Butterfly data: bar chart

Butterfly data: bar chart

Butterfly data: pie chart

Butterfly data: pie chart

Butterfly data: Gantt chart

Butterfly data: Gantt chart

Archive

Butterfly sightings received via the website are archived online for the public to explore in greater depth.

Butterfly data: archive

Butterfly data: archive

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Casual sightings received via the branch website provide a useful snapshot of butterfly activity in Dorset. But for research purposes it’s necessary to combine them with data from formally structured butterfly transects and other recording schemes within the region and nationally.

Website data is exported to the national society’s database annually.

Nationally butterfly recording cycles run for 5 years, at the end of which an Atlas is produced showing the updated distribution of species and population trends.

To encourage recording in under-represented areas we publish an interactive ‘White Holes’ map on the branch website, which combines data from the national database with more up-to-date web sightings.

Butterfly data: White Holes map

Butterfly data: White Holes map

Butterfly data: White Holes map detail

Butterfly data: White Holes map detail

It’s possible to use this map on a GPS-enabled mobile device to locate the nearest White Hole for observation. A list of previously recorded species for each 1km square is also made available.

Over the past 4 years this recording system has gathered more than 180,000 individual butterfly records, contributing to our understanding of these beautiful creatures and the changing environment they inhabit.

Drone mapping

Drone mapping

Drone mapping using a 5 inch DJI Spark drone.

For a few months now I’ve been experimenting with the (non-commercial) use of a small camera drone for environmental monitoring. The quality of the resulting images and the unique perspective it offers have been pleasantly surprising. Its potential applications at relatively low cost are impressive I think.

Red Hill Henge

The site of this scheduled Ancient Monument lies east of the A3 in Surrey and just north of Junction 10 on the M25 motorway.

Map of Red Hill Henge

Red Hill Henge scheduled Ancient Monument (1007905). © Crown Copyright and database right 2018.

‘Making the countryside pay’

In late 2017 Surrey County Council, in collaboration with Surrey Wildlife Trust and their contractors, decided that this Site of Special Scientific Interest (SSSI) would be a suitable venue to pilot their commercial felling operations in the county.

The felling licence issued by the Forestry Commission allowed them to extract 30% on 2 occasions over a 10 year period. Upon visiting the site however the impact at ground level looked far more extensive than I would have expected.

Stacks of felled timber

Felling operations on Wisley & Ockham Commons SSSI

Concerned that the contractors may have exceeded their remit and damaged the Ancient Monument in the process I mapped this area to the north of the site by flying the drone in parallel lines at a height of 60 metres, with the downward facing camera set to take pictures at intervals every few seconds.

Cloud view

With the help of DroneDeploy’s internet cloud software I then stitched the resulting 139 overlapping images together to create an orthomosaic map layer.

Drone map

Area mapped by drone at Red Hill Henge in Surrey.

Orthomosaic map imagery

Orthomosaic detail from drone imagery at Red Hill Henge.

Tracks left by the contractor’s heavy machinery can be seen running across the circular ‘henge-like’ earth bank feature.

Switching to the Normalised Difference Vegetation Index (NDVI) imagery analysis clearly shows the difference between live green vegetation and felled woodland.

NDVI map

Normalised Difference Vegetation Index (NDVI) analysis of felled woodland.

NDVI map

Normalised Density Vegetation Index analysis of felled woodland.

Extra dimension

To help peopIe unfamiliar with the site to visualise the monument in context I then generated a 3D model from the visual point data using DroneDeploy’s online competitor, Pix4D.

3D model of ancient monument

3D model of Red Hill Henge generated from drone imagery.

For terrain features and dense canopy this technique works well, but it struggles to accurately represent isolated trees and finer features. Without resorting to an expensive aerial LiDAR platform it would be difficult to achieve better results however.

Bright Spark

The little drone done good on this occasion, and with minimal disturbance to a historically and environmentally sensitive site… ironically.

DJI Spark drone

DJI Spark drone. Photo: Ralph Clark.

 

Oak Galls: Wasp vs. Plant

Oak trees are home to more than 30 species of gall wasp. The larval stage of these insects induce the plant to produce abnormal growths, known as galls, which enclose and protect them as they develop.

Oak gall wasp larva IV

Galls come in a variety of fantastical shapes, each unique to particular species.

Oak marble gall

Marble galls

Hard woody spherical galls up to 25mm in diameter on the oak stems. Initially green but later become brown.

Created by: Andricus kollari

Oak apple gall

Oak Apple Gall II

These galls have a spongy texture and are brownish white, tinged with pink.

Created by: Biorhiza pallida

Common spangle gall

Common Spangle Galls II

Yellowish gingery brown disc-shaped galls on the underside of oak leaves in late summer and early autumn.

Created by: Neuroterus quercusbaccarum

Silk button spangle gall

Silk Button Surfeit

Golden brown discs with a depressed centre on the underside of oak leaves in late summer through to early autumn.

Created by: Neuroterus numismalis

Knopper gall

Knopper gall

The acorn becomes a ridged woody structure. The gall is initially yellowish green and sticky but later greyish brown.

Created by: Andricus quercuscalicis

Cherry gall

Oak Cherry Galls

Yellowish green or red spherical galls up to 20mm in diameter on the underside of oak leaves in late summer and autumn.

Created by: Cynips quercusfolii

It gets complicated…

Oak gall wasps have complex life cycles, with alternating generations that are either sexual with males and females, or asexual with females only.

The two generations of wasp often produce different types of gall on different parts of the tree, and in some species the two generations alternate between native and non-native species of oak.

Oak Gall Wasps VI

There are also wasps which specialise in injecting their eggs into oak galls. Their larvae then eat the resident eggs or larvae before they emerge.

Chalcid Wasp

The example above shows a type of Chalcid wasp investigating a fresh oak marble gall.

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Puss Moth Metamorphosis

I’ve photographed puss moth caterpillars (Cerura vinula) before, but this summer I wanted to follow them through all 5 stages, or ‘instars’, of their larval development.

Luckily I discovered a batch of recently laid puss moth eggs by searching the exact same aspen sapling chosen by another adult female the previous year.

6 June: Unhatched Ova

Puss moth eggs (Cerura vinula) on aspen

Cluster of puss moth eggs (Cerura vinula) on underside of aspen leaf

12 June: Hatched Ova

Hatched eggs of puss moth larvae (Cerura vinula)

Hatched eggs of puss moth larvae (Cerura vinula), showing signs of early feeding activity nearby.

12 June: 1st Instar

The ‘puss’ moths look a lot more cat-like at this early stage in their development I reckon.

First instar puss moth larva (Cerura vinula) on aspen leaf

1st instar puss moth larva (Cerura vinula) on aspen leaf. The distinctive tail-like appendages are already present.

1st instar puss moth siblings (Cerura vinula) feeding on aspen

1st instar puss moth siblings (Cerura vinula) feeding on aspen

15 June: 2nd Instar

I’d received a shock on my visit the previous day when I found the caterpillars frozen rigid in position, with their backs arched and tails in the air. They looked decidedly dead and I thought they must have been parasitised. Today, however, they were re-animated once more.

Puss moth siblings sharing the same aspen leaf

Puss moth siblings sharing the same aspen leaf

Puss moth siblings on shared aspen leaf

The puss moth siblings were running out of space on their steadily consumed leaf and occasionally paused to whip their tails furiously at each other.

Second instar puss moth larva on aspen leaf

Close-up of 2nd instar puss moth. The jagged tentacles above the head are very prominent at this stage, unlike in the fully mature larva.

24 June: 3rd Instar

9 days later, after vanishing for several days, the two siblings had relocated further up the branch they originally hatched on. Neither was particularly active in the midday heat.

Third instar puss moth larva resting on silk pad

3rd instar puss moth larva resting on silk pad

Third instar puss moth larva resting on silk pad on aspen leaf

The distinctive saddle patterning of the puss moth caterpillar is much more visible by this stage.

28 June: 4th Instar

It lashed with rain on my next visit and the only visible puss moth was trying its hardest not to get pummeled off the leaf. Its silk pad lashed to the surface provides a firm anchor for feet to grasp.

4th instar puss moth on aspen leaf

4th instar puss moth clinging to wet aspen leaf. The hump on its back is now filling out.

4th instar puss moth larva

At this stage in its development the puss moth’s body has begun to envelop its head and the tentacles appear to have retracted.

9 July: 5th Instar

A further 11 days later I returned to find only one of the original 4 puss moth siblings remaining, now in its magnificent mature larval form.

Fifth instar puss moth larva

5th instar puss moth larva. All the outlandish features of the mature larvae are now present, including the lurid pink face, flagellae and false eye spots.

Fifth instar puss moth larva detail showing extended pink flagellae

Detail showing extended pink flagellae. When threatened the puss moth extends these whip-like appendages from its tail end and waves them around crazily.

To be continued…

Soon after reaching this mature larval stage the puss moth stops eating and leaves in search of a safe place to pupate. Its transformation into the furry white adult moth can then begin. Despite much searching I couldn’t locate any pupae. Next time maybe!

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WPOTY 2014: Shortlisted

Another year, another shortlisted image! This time in the ‘Invertebrates’ category:

Pond skaters

River sprites

Canon 600D + 100-400mm f/4.5-5.6L IS USM lens; 2 sec @ f/40; ISO 100

This is a long exposure image of pond skaters (Gerris sp.) in motion, taken in the shady bend of a local river one summer afternoon. Shortly after this frame was captured my tripod toppled over and the camera went for an expensive swim!

Unfortunately this year’s entry again failed to make the final cut. Congratulations to The Winners.

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Amphibian Kama Sutra

Common toads in amplexus

Common toads (Bufo bufo) spawning

After emerging from hibernation in early spring, toads migrate back to their breeding ponds.

Males fight to secure mates and often outnumber the females at some sites. When this happens the female may be grasped by several males in a position known as ‘amplexus’, as they compete to be in the best position to fertilise her eggs.

Common toads in amplexus

Group of toads in amplexus

Common toads in amplexus

Spawning might look fun but can also be life-threatening!

Common toads in amplexus

Toad sex is apparently a moveable feast!

The common toad is widespread in Surrey, however populations appear to be declining. Where toad migration routes cross busy roads there can be many fatalities, and local conservation groups police ‘Toad Crossings’ at dusk to help them safely across.

Common toad crossing track

This toad was late to the party, but managed to avoid oncoming traffic

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