After emerging from hibernation in early spring common toads (Bufo bufo) migrate back to their breeding ponds at night. Sometimes this involves crossing busy roads and many toads are sadly hit and killed by passing cars.
Each year volunteers working with charities such as Froglife and local Amphibian and Reptile Groups attempt to ferry migrating toads, frogs and newts to safety at known crossing points.
Male toads grasp females in a position known as ‘amplexus’ as they attempt to fertilise her eggs. Often a mating pair can be found together before they reach the nearest pond. When this happens males hitch a free ride!
Advancing conservation science through public engagement on digital platforms
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.
Initially butterfly spotters are directed to a web form which collects personal info, location details including grid reference, and species observed.
This information is then inserted into the Dorset Branch web sightings database.
Local experts 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.
Questionable records can be studied in more detail and recorders contacted to clarify information as necessary.
Verified records are instantly published to the branch website, using a number of graphical representations for easy interpretation.
Butterfly sightings received via the website are archived online for the public to explore in greater depth.
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. National 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 an interactive ‘White Holes’ map is published on the branch website. This combines data from the national database with more up-to-date regional web sightings.
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 presented.
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.
Experiment in environmental monitoring using a small consumer 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.
In late 2017 Surrey County Council, in collaboration with Surrey Wildlife Trust, decided that this Site of Special Scientific Interest (SSSI) would be a suitable venue to pilot their commercial felling operations in the county.
A felling licence issued by the Forestry Commission permitted 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.
Concerned that contractors may have exceeded their remit and damaged the Scheduled Ancient Monument in the process I mapped an area to the north of the site, 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.
With the help of DroneDeploy’s internet cloud software I then stitched the resulting 139 overlapping images together to create an orthomosaic map layer.
Tracks left by the contractor’s heavy machinery can be seen running across the circular ‘henge-like’ earth bank feature.
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.
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.
The little drone done good on this occasion, and with minimal disturbance to this historically and environmentally sensitive site ironically.
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.
Group of toads in amplexus
Spawning might look fun but can also be life-threatening!
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.
This toad was late to the party, but managed to avoid oncoming traffic
Harvest mouse (Micromys minutus) captured on survey after dark
Last week I joined Surrey Wildlife Trust on a harvest mouse survey in wetland habitat beside the River Wey.
Harvest mice are tiny rodents 5cm in length. Their remarkable prehensile tails add an extra 6cm. They live in long tussocky grassland, reedbeds, hedgerows and around woodland edges, building a spherical nest of tightly woven grass, high up amongst the stems. We found several examples at this site:
Harvest mouse nests are woven from a mixture of living and cut grasses which provides excellent camouflage
Nests are the most obvious sign of harvest mouse activity since the animals are especially active around dawn and dusk and rarely spotted in the thick vegetation.
Dozens of rodent-friendly traps of different designs were set in the thick wetland reeds and grasses. Surrey Wildlife Trust staff and volunteers returned three times each day over the course of a week – at dawn, midday and dusk – to ensure that no trapped animals were left for any longer than necessary.
Rodent trap baited with peanut butter, bird seed and dried blowfly larvae
After retrieval from the trap harvest mice are transferred to a transparent bag for weighing and sexing:
Harvest mouse recovered from trap
Harvest mice weigh only 5g on average
Once the details of each rodent have been recorded a small patch of fur is trimmed to identify any animals which are subsequently re-captured.
Marking harvest mouse – a delicate operation!
The highest number of individuals captured was 12 one morning, making this the most abundant site for harvest mice in the county at present.
Harvest mice require very careful handling by trained experts
With thanks to Surrey Wildlife Trust staff and volunteers.
The Crouch Oak once marked the perimeter of Windsor Great Park and is thought to date from the 11th Century, making it in excess of 900 years old.
This ancient tree now looks a little incongruous as a modern residential estate has grown up around it.
The Crouch Oak at night with passing traffic
It’s interesting to compare depictions of this tree from the 19th Century and in 1904 as wooden fences are replaced with metal railings and a dusty track becomes a surfaced road. The oak also enjoyed an additional limb in those days.
In more recent times the Crouch Oak survived an arson attempt in 2007 and is now fitted with metal grilles across its hollow openings to prevent a repeat.
Metal grille stops burning objects being thrown inside
To see the Crouch Oak for yourself follow the map below to the bend in Crouch Oak Lane: