The Cumbria Bat Group kindly let me come along on a hibernation survey at Easegill Caves in January 2017. We hiked up to Upper and Lower Kirk Caves to see what we could find, then descended using ropes and caving ladders into Link Pot to explore an underground cave network some 15m down.
We found good numbers of myotis species including Daubenton’s, Natterer’s and whiskered/Brandt’s/Alcathoe – these last three are grouped as it’s very difficult to distinguish these three without disturbing the bats. We also found a small number of brown long-eared bats hibernating too.
It’s important to note that disturbing hibernating bats is illegal without a licence from Natural England – this survey was led and supervised by licenced bat workers who ensured that disturbance was kept to a minimum whilst allowing the bats to be identified and counted. If you find a bat in roosting you should take great care not to disturb it especially during the winter as they may rouse from torpor at an inappropriate time and be unable to then survive the winter. If you do find a roosting bat – let your local Bat Group know! More details at the bottom…
The video below shows a summary of the seven hours we spent out in the hills, in just under three minutes!
The following photographs show a few of the hibernating bats we identified on the surveys.
It’s not only bats we found in the caves – plenty of cave spiders and hibernating moths too including herald and tissue moths.
If you would like to get more involved with your local bat group and help out on hibernation surveys such as these, you can find your nearest here. Many thanks to the South Cumbria Bat Group, and Rich Flight in particular, for a great opportunity to explore the caves and see plenty of roosting bats!
Each winter for the last few years, there have been starling murmurations over Grantham and this year is no exception! I saw them gathering on a pylon in the fields beside Harlaxton as I drove along the A607 in this evening, and as I drove past they all rose en mass and began to flock over the western tip of Grantham. I parked up for a few moments to watch this incredible spectacle of aerial gymnastics.
There are several theories as to why starlings flock together like this and treat us to such a display. They gather just before roosting, which they do communally, and so you see smaller flocks gradually join the largest flock so that the numbers grow and grow before they drop down to the trees and shrubs where they spend the night communally. This grouping together may allow them to exchange information on good feeding spots, or just help them to gather with the rest of the local starlings to maximise the warmth which multiple bodies brings on cold winter nights.
The birds move in unison, twisting and turning in shapes a little like those you’d see in a lava lamp, and this behaviour increases in speed and complexity if there is a predator about. This is believed to be another of the reasons for the murmuration behaviour. Safety in numbers is an instinctive behaviour for many species – including birds, fish and mammals – and it works on the basis that if you are in a large crowd, there are many targets beside yourself which makes it unlikely that a predator will get you individually. The dynamic flight patterns of the murmuration adds a further element of safety by confusing the predator as the flock bends, twists and turns as one.
Starlings are a common sight, but they are actually a red list species. Each bird in the UK is given a colour-coded assessment based on the current status of the species. This works on the traffic light system – green indicates least conservation concern whilst red indicates the highest conservation priority. Starlings are on the red list because, despite these large winter flocks appearing impressive, long-term monitoring by the British Trust for Ornithology shows that starling numbers have fallen to just 1/3 of their population in the mid-1970’s. If this decline were to continue along the current trend, then it would be only a short time before starlings were all but extinct.
The flocks will begin to disperse as starlings pair up and establish nests, so take the opportunity to watch this natural phenomena whilst you have the chance! The hour before sunset is the best time to get out and look for them, and they are currently focused on the western tip of Grantham, sometimes moving over the centre earlier in the evening.