RSPB Mersehead Recent Sightings 16th – 22nd January 2021
Although a varied week weather wise, and with its fair share of rain, the sun came out to greet us these past couple of days. The setting sun cast a rosy hue over the reserve on Thursday evening.
Sunset looking South West. Photo Credit: B. Taylor
The week started with the Wetland Birds Survey across the Mersehead reserve with an exciting total of 11,608 birds. With some areas of the wetlands still icy, this prompted me to read up on the adaptations that wetland birds have in order to survive these harsh conditions. Through the winter, birds’ feet are exposed to frozen ground and water, and yet their movement is fully retained. This is achieved through a counter-current blood flow system where the blood vessels going toward and away from the feet are very close together, allowing heat exchange. Warm blood in the arteries supplying the duck’s feet heats the blood coming away from the feet. This lowers the temperature of the feet whilst maintaining a high body temperature. Therefore, the difference in temperature between the feet and the ice is reduced, minimising heat loss.
Barnacle Geese. Photo credit: B. Taylor
Keeping dry is clearly essential for keeping warm – not a problem for water birds which have a highly developed ‘preen’ or ‘oil’ gland. This gland, located at the base of the tail, secretes an oil which helps to keep their feathers waterproof and in good condition. You might notice ducks rubbing their head and bill over this gland and then onto their feathers whilst preening. All these adaptions are energetically expensive, and birds must maximise feeding while minimising unnecessary movements which explains why fewer ducks than usual were seen across the wetlands. Despite this, 188 Pintail, 73 Wigeon, 17 Shoveler, 25 Mallard and 201 Teal were counted across the reserve.
Waders showed up in impressive numbers, with 2,840 Dunlin, 3,500 Knot, 1,322 Oystercatcher, 28 Ringed Plover, 319 Golden Plover and 22 Grey Plover recorded. Although Ringed Plover are often found within groups of other waders, they stay put when these flocks take off, giving the chance for a quick count.
Counted for the first time this season were 4 Little Grebe. These dumpy water birds have the genus name Tachybaptus which comes from the Ancient Greek takhus "fast" and bapto "to sink under". This name is quickly explained if you watch them hunting for food. As strong divers and swimmers, Little Grebe will dive under water and pop up somewhere far away, having searched for little fish and underwater invertebrates to feed upon.
Little Grebe. Photo Credit: Ben Andrew (rspb-images.com)
As you walk through the woodland, you may notice red tags hanging from some of the trees. These identify possible bat roosts. If you look up into the canopy, (the lack of leaves makes winter a good opportunity for scouting out roosts) you might be able to spot grooves, fissures, or broken branches, all of which could hide hibernating bats. There are 10 species in Scotland, all of which are found around Galloway.
During Winter, bats seek out humid and protected sites for hibernation. These sites mostly fall into three categories: trees, built structures (barns and bridges), and underground sites. Bats will start to emerge around March and April and then become fully active in May, feeding, and looking for maternity roosts. Once they emerge, it is possible to hazard a guess at the species based on flight patterns, but listening to their echolocation calls through a bat detector makes identification much easier to the trained ear.
Red tag indicating a possible bat roost. Photo credit: B. Taylor
This week saw the continuation of key habitat work preparing the reserve for Natterjack Toad breeding. Breeding occurs between April and July and toads must move from their winter burrows in the sand dunes to shallow ephemeral pools. Natterjacks are able to run very fast over short distances, hiding in short undergrowth before darting forwards to dine on a range of insects and marine invertebrates. To provide the best habitat for what are Scotland’s rarest amphibians, the vegetation bordering the pools and ditches is cut short so the toads are able to hunt and breed effectively.
Cutting the sward to prepare for Natterjack Toads. Photo Credit: B. Taylor
Whilst working we noticed flattened grass at the edge of the field and set up a trail camera to record the animal responsible. Sure enough, when I checked the footage, an Otter can be seen using the space as a cut-through.
Otter captured on a trail camera
Wednesday brought a low fog over the reserve, giving the Saltmarsh an eerie quality where the yapping of Barnacle Geese seemed to come from all directions. Walking over the Merse I watched 2 Little Egret take to the air whilst I listened to the distinctive cry of the Curlew. I was then startled by the 13 Snipe which rocketed out from the undergrowth nearby.
Eerie scenes over the Saltmarsh. Photo Credit: B. Taylor
Walking back to the farm buildings, I was puzzled by a gelatinous, transparent substance I didn’t recognise. A quick google showed there to be some discussion of what this substance (named Star Jelly) might be. It’s name is derived from the bizarre myth that it is fallout from meteor action. It is understood to be frog spawn jelly; either exposed or regurgitated when birds are eating amphibians.
Star jelly (Frog Spawn Jelly). Photo Credit: B. Taylor
A reminder that the Big Garden Birdwatch 2021 is happening the weekend 29-31 January and is open to everyone. It's not too late to sign up!
Beth Taylor, Residential Volunteer