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Somerset is a well-wooded county with plenty of livestock farms, suggesting that Rooks should be a relatively common farmland bird in the county. During the Somerset Atlas of breeding and wintering birds 2007 – 2012, confirmed breeding records of Rooks were received from 53% of tetrads in the County. However, since then records of rookeries reported in Somerset Birds are very few and far between. Are we failing to record most of our Rookeries, or have they simply vanished from the County? We need to check, so here is the BTO Somerset & SOS Rookery Survey!

This survey runs from 1st March to the end of April. Many Rook nests persist over the winter, depending on the wind conditions, so it is possible that some nests seen in early March are the remnants of the previous year’s nests. Some of these nests will be renovated and re-occupied; although this is not always the case and old nests can be used as nesting material for new nests. March is the most active time for nest building, so early in the month is a good time to locate active rookeries to survey. Peak nesting activity is between late March and mid-April, so any nests that appear to be active then should be counted. An active nest (known as an Apparently Occupied Nest: AON) will contain a sitting bird, or have adults visiting to feed juveniles. Rooks only have one brood per year, so their breeding season should be over before the trees come into leaf (unless they’re nesting in evergreen trees).

For the purposes of this survey a rookery is defined as any group of nests 100m or more from the next nearest group. This definition should be relatively easy to apply in the field, but do be aware that some larger rookeries may be somewhat fragmented in distribution.

You can still help even if you don't know of any rookeries, since negative data is also very useful.

To make running such a survey easier an online system for allocating sites and collating data has been produced by the BTO, with thanks to sponsorship from Somerset Ornithological Society. This online system will enable you to register squares in a similar way to other BTO surveys; it’s now up and running so you can start surveying our Rookeries in 2022.

Here’s the link for booking your squares:   As at 23rd February, there were a number of tetrads in which Rookeries were located in 2021 but had not yet been allocated in the new survey - for details click here.

For information, below there is a map showing breeding records for Rook during the Somerset Atlas period. It might be helpful to anyone wishing to compare tetrads on this map with those in the link above.

For full details, please click here for the Guidance for Surveyors and here for the Recording Form, or contact Eve Tigwell on

Eve Tigwell
BTO Regional Representative for Somerset
WeBS Local Organiser -  Somerset, including The Levels 
Heronries Census Organiser - Avon & Somerset
Full details of all surveys on, or please contact me


Nightjar Pilot Survey 2019

We now have the data for the above survey, conducted jointly by the Society, BTO, Forestry England and the Blackdown Hills AONB. It was very successful and produced good results. A full survey is intended for 2020. For the results and methodology, click here.

Become a Member of Somerset Ornithological Society.