Last year we delved deeper into the world of bioacoustics at the Great Fen. We began gathering data on bird calls; 24 hours a day, seven days a week. Wilder Sensing is a company that offers us the benefits of artificial intelligence, to identify, compile, and analyse bird sounds.

Following liaison with the Somerset Wildlife Trust, at their new site at Honeygar, we  started trials with our first audio sensor at Speechly’s Farm. As some of you may have seen on the ‘Fens’ edition of Countryfile last July, we also set one up on land under restoration since 2011.

These sensors can record for weeks on end, and so be left to themselves to listen in on the natural world around them. They passively monitor the wildlife, disturbance free, which is a of great benefit during the breeding bird season for example. At the moment, I collect the data from each sensor, and then upload it to a website, ready for processing.

Once loaded, the files generated by the sensors are sampled every three seconds for three seconds (so no overlap or gaps); so a two-minute song, assuming each segment is recognised as the species calling (e.g. a wren), will generate 40 records (i.e. 20 records per minute). This does, of course, mean the birds with a long continuous call or song will generate a lot of records.

In December last year, I calculated that the sensor at Speechly’s Farm has been recording for nearly 6,490 hours, generating over 28,000 files. Between July and December, we had been recording on the restoration land for over 3,860 hours.

The data is processed and generates tagged files, in this case 15 minutes long. Each one can provide an amazing insight into the natural world.

A variety of species have been recorded, and initial work has been done to develop several indices using the data generated, such as for raptors. As it turns out, 10 species have been detected at Speechly’s Farm, including barn owl, hobby, osprey, and short-eared owl.

The graphs below show the number of records per species each week (bar graph), and the number of species recorded each week (line graph).

Long-term, Wilder Sensing hopes to expand the types of wildlife being identified, to add grasshoppers and crickets, and mammals, and use hydrophones to listen in on the underwater world. They are also developing the use of triangulation, to be able to pinpoint the location of the sounds being identified. Once equipment is developed to use 4G, we won’t even need to collect the data ourselves, but just wait for it to appear on the website!

Even so, this will not replace the wealth of information provided by the Great Fen volunteers and staff, out in the field. It does not tell us that we had 81 snipe in one field at Speechly’s Farm last November, recorded by volunteer Andy Frost. It does confirm the record of a pink-footed goose, heard flying over Rymes Reedbed that same month by Reserves Officer, Jasmin Atkinson. It adds another tool to our suite of monitoring methods, one which also allows us to sample the soundscape of the Fens and allow us to promote ourselves in the digital world, and allow those unable to engage closely with wildlife to enjoy the results of our efforts to conserve it.

Henry Stanier (Great Fen Monitoring & Research Officer)