The British Trust for Ornithology (BTO) recently launched a new Bird Atlas project for the UK and Ireland. The new atlas will map different bird species and will rely largely on volunteers to carry out survey work. One of the main ways in which the surveying for the atlas is done is through Timed Tetrad Visits (TTVs). Each volunteer is assigned various ‘tetrads’, which are 2×2 km squares. They then make four timed one or two hour visits to the tetrad in winter and summer and count the birds they see and hear.
Last weekend I did my first TTVs in two tetrads along the lower reaches of the River Don in Aberdeen. Doing the survey involves using ears as much as eyes, and I became very conscious that my hearing skills were being tested to a much great degree than during ‘normal’ birding. Most times when I go birding, I’m looking and listening for birds that are out of the ordinary in some way or another. An effect of this is that I tend to filter out the commoner birds, wonderful though they are. It’s not so much that I don’t hear these commoner birds, it’s that I sometimes don’t register hearing them; I don’t consciously tell myself what I can hear. This is a kind of ‘unconscious identification’ that is probably important in all sorts of areas of perception. We perhaps only realise we’re doing it when we suddenly find what we were unconsciously listening out for - by hearing something different, we realise we were listening all the time.
But surveying for the atlas requires that every bird, heard or seen, is registered not just consciously but in pen and ink on the pages of a notepad. Last weekend I found it surprisingly hard work to spend four hours registering and attempting to identify every bird I found. There aren’t too many birds singing at the moment here in Aberdeen, aside from lots of Robins and a few Wrens, but there were lots of subtle calls that tested my skill at identifying common vocalisations to the full. I realised how hard it can be to distinguish between the calls of various tits, most of which give some rather similar high pitched twittering calls, as well as a few more distinctive sounds. Knowing whether a call was a great tit or blue tit could sometimes be a challenge. Likewise song thrush and robin both give some rather soft contact calls that can sound rather similar. Could I tell the difference? Sometimes the answer was no.
So if you’re doing atlas work in the UK and Ireland at the moment, or if you’re doing some other kind of bird surveying, I’d be interested in hearing about the role that listening plays in the survey work and about how you think surveying influences your listening skills.