BTO: Rooks reveal their resourcefulness

Rook. 'Picture: John Harding/BTO ANL-140407-112359001
Rook. 'Picture: John Harding/BTO ANL-140407-112359001

Rookeries have been a feature of Suffolk’s rural landscape for many generations.

Although most obvious during the first weeks of spring – before the leaf buds have burst – activity at colonies continues through into mid-summer, which is when the last of the young leave the nest.

Rooks are social birds, both during the breeding season and at other times of the year, and this has led to the evolution of a number of different display and signalling behaviours. Many of these are used to communicate the status of a particular individual or to advertise the ownership of a nest. Some, such as the bowing and tailing fanning display, serve to resolve potential conflicts and avoid the fights that may wound an individual or, ultimately, lead to its death. Alongside these are more tender displays, used to reinforce the bond between a bird and its mate. These bonds can last over many seasons, underlining that this is a relatively long-lived bird. In the wild a rook can live for 20 years or more, a fact that has been revealed through the efforts of volunteer bird ringers.

Like other members of the crow family, rooks show a degree of resourcefulness and intelligence. This allows them to recognise new feeding opportunities and to take advantage of them. Such resourcefulness can sometimes be seen in the individuals attracted to garden feeding stations, where the food available on bird tables and in hanging feeders is seen as fair game. Rooks have even been observed to haul up bird feeders hanging from a branch on a bit of string. By pulling on the string with its bill, lifting the feeder a few inches, and then standing on it before repeating the process, a rook may gain access to food that was otherwise out of reach.

These clever birds have been observed exhibiting other behaviours too and laboratory studies have even revealed that rooks may use tools to get at food. There has been little work on these behaviours in the wild, however, and this is where a new study by the British Trust for Ornithology’s (BTO) Garden BirdWatch Team is hoping to provide some answers. They are asking for garden birdwatchers to report on what their garden-visiting rooks get up to. There is also the opportunity to try some simple experiments in your own garden to establish just how resourceful these birds can be. One experiment tests whether rooks will drop stones into a narrow jar, half-full with water, in order to raise the water level and, by doing so, gain access to the mealworm floating on the waters’ surface.

Rooks are not always welcome at garden feeding stations because they can arrive in numbers and make short work of food put out for other species but they remain interesting birds and well worth further study. See www.bto.org/rooksurvey for more information.