This local survey is ongoing.
The Herts Bird Club leads the action Tree Sparrows to protect their breeding sites in the county.
The last remaining Tree Sparrow breeding colony in Hertfordshire nests in boxes in the Tyttenhanger area. The main breeding site is on private land and the nest boxes are monitored closely by Herts Bird Club members (see photo below).
Herts Bird Club provides supplementary feeding for the birds all year round at two sites. There is public access to the feeder at Tyttenhanger Farm, it is located in an enclosure to the east of Lawson's builders merchants yard. You can get good views of the Tree Sparrows in the hedge and on the feeder from the public footpath and field margin.
After several difficult years this strategy seems to be paying off and the numbers of birds has stabilised.
All the Tree Sparrow pulli are ringed every year and some have been fitted with electronic monitoring tags. You can see the PIT tag fitted to the sparrow's leg in the photo. So we are starting to understand more about these lovely birds and their needs.
Reports from the Tree Sparrow Project Team are available for 2010 and 2009 and a paper was published in July 2014 the Hertfordshire Bird Report 2012.