The Ebbs and Flows of the Breeding Season

RSPB Mersehead Blog 13^th – 19^th April 2024

Throughout the breeding season our reserve team are out and about at all hours of the day and night diligently surveying a variety of species employing a variety of different methods and techniques.  To give you a flavour of the wide variety of survey work we undertake here at Mersehead, in the last week alone we have continued to survey our brilliant Barnacle Geese (Branta leucopsis), undertaken two different types of Natterjack toad (Epidalea calamita) surveys, our Lapwing (Vanellus vanellus) nest monitoring is fully underway and a particular favourite survey of mine, Water Rail (Rallus aquaticus) was undertaken.

But before the excitement of the surveys comes some tidal news from Kirkconnel…

Elevenses on the Merse (Alas No Cake!)

In last week’s blog you read about how nine metre high tides almost completely covered our livestock fencing at RSPB Kirkconnel.  As a result, this week our reserve team prioritised a visit to the reserve, ensuring any tidal destruction could be assessed and repaired as quickly as possible.

In order to gauge the level of potential damage our team walked miles of fence-line, checking each section and removing any flotsam and jetsam marooned by the tide.  In the end we were fortunate that minimal damage and detritus was found – phew!

One positive of a fence-line audit at Kirkconnel is that you are walking across large areas that are not well trodden.  This means that we often stumble across wildlife either at the last minute or unexpectedly and this visit was no exception as one half of our team happened upon a Mallard (Anas platyrhynchos) nest with a clutch of 11 (yes, eleven) eggs!  While it may seem a lot, this actually sits within the average clutch size (10-12) of the UK’s commonest duck species. When unintentionally stumbling across wildlife like this it is important to move on quickly so that the adult can return to the nest.

Mallard Nest with a Clutch of Eleven Eggs at Kirkconnel. Photo Credit F. Sanders.

Did you know? Each individual Mallard egg weighs approximately 54g and is 57x41 mm.

Natterjack Nights

Natterjack toads require very specific conditions to begin breeding but a key factor is the air temperature really needs to be a minimum 5℃, although other factors such as wind and precipitation do play a part.  

Natterjack are nocturnal breeders meaning nighttime surveying is a must if we want to have a real grasp of, in particular the adult male population.  The adult males stand by the edge of shallow ephemeral pools letting out a chorus of croaks to attract the lesser seen females, who only come out of their burrows when ready to mate.  When several males begin calling the sound can be heard up to a mile away!

Beginning at dusk, equipped with range of luminous tools, our survey team spent four hours listening and searching for all the Natterjacks we could find.  Every discovered toad was carefully handled in order to determine and record its sex and size.   Just after midnight a yawning but happy survey team had found over 100 individuals, the majority male, including several toads in amplexus.

Amplexus, shown in the photo below, is the mating position for frogs and toads, whereby the male positions himself on top of the female and grasps on with his front legs.  

Natterjack Toads in Amplexus on the Nighttime Survey at Mersehead. Photo Credit F. Sanders

After the Night Before

As previously mentioned we survey Natterjack toad with two different methods to ensure we get a good grasp on the population we have here at Mersehead.

Our second survey involved our team walking the same areas as the nighttime survey except this time during the day and specifically looking for spawn string laid by the Natterjack females.  Our team very carefully observed the pools and marked the location of any spawn strings we found. 

Female Natterjack only lay one spawn string and so by counting them we ensure we have a really accurate count of the female population, plus the male population from the nighttime surveys.

Our Team Hard at Work Searching for Spawn String.  Photo Credit F. Sanders

The Natterjack Toad is a European Protected Species therefore a licence is required to go looking for the toads. Join our Natterjack Night Guided Walks on Friday 19th & Friday 26th April when you will be able to accompany an experienced member of the Mersehead team to visit the breeding pools and hopefully see these rare amphibians as dusk descends over the reserve.

Reeds, Rail and a Chorus

Participating in, and being able to handle a special species such as Natterjack toad is a real treat, however my highlight of the week came with a dawn survey of Water Rail.

Surveying the often heard, little seen, Water Rail is a special experience.  Setting off at dawn, rather luckily on the calmest morning of the week, our team headed into the reedbed listening for its distinctive call.  Keeping a set distance between observers we traversed the same areas, periodically waiting, straining our ears and listening out for the unmistakable squealing, sharming call of the Water Rail.  Each observer was armed with a map and recorded where they heard a call, allowing us to estimate the breeding population we have at Mersehead; which I am pleased to announce is eleven.  

I have to say that the call and the bird are special in and of themselves however it was the atmosphere during the survey, the calmness of the reeds slipping into the erupting dawn chorus which drew goosebumps.  Swallows (Hirundo rustica) began to dive and swoop overhead, Sedge Warbler (Acrocephalus schoenobaenus) sang for the first time this year on reserve, Reed Warbler (Acrocephalus scirpaceus) was in fine voice, and then silence as we all stood gazing in wonder at the graceful flight of a Marsh Harrier (Circus aeruginosus) alongside us.

Sound of the Reedbed Including Sedge Warbler. Recording Credit, Nick Bone.

Reed Warbler Singing During the Water Rail Survey.  Recording Credit, Nick Bone.

I have a real personal passion for bioacoustics so being able to wander through such a special landscape at that time was a real privilege that will live long in the memory.

Nick Bone, Trainee Warden

At Mersehead you will find the RSPB’s only self-catering holiday cottages - Barnacle and Shelduck. Available summer dates are currently going quickly, follow the links to book your next holiday.

Upcoming events: For more information on individual events and to book a place, please go to our website: https://events.rspb.org.uk/mersehead

 *Flooding - Please note that Mersehead nature reserve is prone to flooding during periods of high rainfall and/or strong winds and tidal surges. To avoid disappointment at these times, please contact the reserve in advance of your visit by email in the first instance at mersehead@rspb.org.uk or check the RSPB Dumfries and Galloway Facebook Page for daily updates.