Part of St Mary's Land in Warwick has been cordoned off this week.
The area has been taped off and signs have been put up ahead of pest control work.
A spokesperson from Warwick District Council said: "On Wednesday April 28 active rodent burrows in the middle of the racecourse, will be treated by pest control, in addition to the stables and yard on the Racecourse site.
"The area of land where the wild bird crop is located has become an active feeding ground for rats as well as the stables.
"Therefore, under the request of Warwick District Council’s green space manager, the Racecourse has contracted Conquer Pest Control to carry out the required works in conjunction with their own control .
"The area in question on St Mary’s Lands has been taped off with hazard tape and signs have been erected.
"The active burrows will be filled so the control methods used will not pose any threat to any nesting birds which are all outside of the area being treated.
"Visitors are being told to ensure that they or their pets do not enter the taped off area for 48 hours from Wednesday April 28 to Friday April 30.
"Warwick District Council and Warwick Racecourse thank the public for their co-operation."
The Friends of St Mary's Lands group has criticised the work being done on the site.
A spokesperson from the management committee of the Friends of St Mary's Lands said: "Warwick District Council applaud themselves on their ecological scruples in erecting fencing to protect nesting birds on St Mary’s Lands.
"Yet, on the other hand, they are allowing an extremely toxic substance to be placed very near the nesting site with a notice marked by a skull and crossbones which states 'Very toxic gases. Danger to life'.
"It would appear that Warwick District Council have contracted this work on behalf of the Racecourse who are experiencing problems with rats but this is a public open space currently being enjoyed by hundreds of people on a daily basis."