Stone the crows
We were recently posed a very interesting question by Ian Bailey in Gloucestershire: why might a Jackdaw deposit over several days a handful of various sized stones, up to quail's egg in size, on the crossbeams of our 2.5metre high garden pergola? It was not the first year that Ian had found stones on the pergola but previously the culprit had not been seen in action.
Our feeling was that this bird was probably a first-year bird that was exploring its way in the world. Jackdaws don't breed until they are two years old and so juvenile birds will spend much of the next few months developing their life skills. There is a resemblance to this picking up of stones and dropping them to the picking up sticks and dropping them into cavities such as chimneys, as is sometimes the case when nest building.
However, Jackdaws are also inquisitive birds and are known to pick up unusual objects, sometimes seemingly for no apparent reason. Indeed, it has been documented before that they will pick up stones.
Making the most of BirdTrack data
We have been working to produce useful summaries for bird reports using data from the millions of annual BirdTrack records.