Derek Crawley reports on a search for harvest mouse at Richmond Park in South London.

I am used to being asked to go on field excursions to establish the presence of harvest mice via nest searches, but was recently visited Richmond Park in London with the purpose of not finding them. The reason of this search for absence of signs or sightings was that Battersea Park Zoo are looking to do a harvest mouse re-introduction scheme into the London park but did not know if there was suitable habitat or an existing population. They had been in touch with the Mammal Society to ask for advice and I offered to survey the deer park for suitable habitat and to see if there was a pre-existing population.
First, we checked the-biological records locally and on the National Biodiversity Network, with no results. The ranger service in the park had no records from the historical records of the park.

Arriving at the park I was greeted by the sight of the tired looking fallow bucks who had just finished rutting (later in the day we also spotted red deer groups). I met with Jamie Baker from the zoo and explained that although there was lots of areas of tall grasses, the tussocks needed had not developed due to grazing pressure. Some areas of developed tussocks were found initially but these were isolated in a sea of short grass but it allowed for a training session on how to search for harvest mouse nests and signs of field vole.
We drove around the park carrying out a quick survey for the correct vegetation. This we found in abundance by Pens Pond café and the Spankers Hill woodland car park, as well as by the edge of the lake/ pond. Here we carried out a nest search. With no signs being found it did have the potential to sustain a population of mice.
It was decided that Jamie should organise a bigger survey with volunteers to double check for presence of harvest mice and that he would undertake assignations nest search training and actually find and recognise actual harvest mouse nests before organising his volunteer force.
If you would like to get involved in this project then do contact either the Mammal Society or Battersea Park Zoo as they will need lots of help surveying and then monitoring the relaxed population.
Derek Crawley is the founder and Chair of the Staffordshire Mammal Group, which was established in 2000. He has spent 37 years watching otters at Leighton Moss and elsewhere. He is co-ordinating the Mammal Society’s UK Atlas project atlas@themammalsociety.org.