Bird Surveying Techniques 007 would be proud of!

To catch a corncrake… without actually catching one!

There are many ways to capture a corncrake that do not involve nets or tags or physically holding one. The following blog is an example of RSPB's more 007-esque survey techniques.

We can learn a lot more about these elusive but very vocal birds without intervening in their natural behaviours, just some equipment from 'Q' is needed!  Corncrakes specialise in staying hidden in tall vegetation but the male corncrake call (https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/corncrake/) show that they are not at all shy of broadcasting where they are at all … you just have to be out in the wee small hours to hear it. Look up John Bowler's blog, describing what it like going out in the middle of the night to survey corncrakes. https://community.rspb.org.uk/getinvolved/corncrake-calling/b/corncrake-calling/posts/by-the-dead-of-night 

Going nocturnal is not a lifestyle that all would choose and the development of some very clever hardware have given some of us a few more hours sleep over the summer survey months.  Audiomoth is a sound recorder, it can listen at audible frequencies as well as  into ultrasonic frequencies. These devices can be pre-set to record either continuously or over set periods over many weeks. It can pick up calls from over 50m away but beware - raindrops, wind, cars, owls, wind in vegetation and many other noises may mask the calling corncrakes. The Hebrides are often a surprisingly noisy place at night!

Although we may gain a few more hours sleep, for every hour of recording, you have an hour of listening when you retrieve the device. Software is currently being developed to  recognize different noises and calls. The BTO has software which will allow you to upload recordings and help ID bat species and bird call identification is coming soon.

Weatherproofing is needed and remembering where you left it is another issue…

With Audiomoth we can find out whether or not a corncrake is present without waiting up all night to do so, and it is excellent at confirming calling male locations when we have had a dubious report. But unfortunately to cover large areas you’d need a lot of recorders, the human ear wins out at this scale. We also use it to check if there are any calling males about before carrying out any mid-season habitat work (eg bracken eradication) as avoiding disturbing the birds is paramount. It also can pick up the lesser known ‘soft call’ (communication between males) and the very rare 'bark bark' of a female corncrake. 

These types of surveying techniques are fairly new but our fellow conservationists with Corncrake Life in Ireland (https://www.corncrakelife.ie/) are conducting exciting new research with bio-acoustic equipment. Identifying females calls and even chicks begging for food can help build a better picture of the breeding success of these secretive birds.

Technology is also available which allows us to identify individual corncrakes! To our ear the calls all sound the same, but from a recording, a sonogram can be produced. For a number of years, Robert Arnold and Shelagh Parlane have been looking at the call patterns of corncrakes on Skye to see individual males can be recognised - the short answer is most likely yes! Please contact RSPB on Skye if you would like to know more!

Our initial results suggest that we still have a lot to learn about corncrakes and their behaviours and we are hopeful that those on the Corncrake Life Project with cutting edge technology and experts in the field will find out more, so keep an ear out - secret agents welcome!