Valencia Waste Management, previously Viridor, which is responsible for restoring the Beddington Farmlands, claimed the killing of foxes is necessary to protect birds on the nature reserve.
However, locals were concerned about the time of year the cull was taking place meaning cubs would be left starving without their parents.
Animal rights activist Saffron Gloyne claims the company could have got better fences before resorting to shooting the animals,
She said: “Obviously I don’t agree with it from a moral point of view. But this has all come about from mismanagement, they did not make the investment in fox-proof fences and now they have gone for the cheapest option.
“This is what happens when a waste management company manages a nature reserve.”
Valencia said it could consider “lethal management interventions” if there is further “predator access”.
The company said it would consult with panels tasked with the management of the farmlands.
A spokesperson for Valencia said: “Valencia has undertaken management of the fox population within the wet grassland habitats over recent weeks, which is now complete.
“In line with the procedures, the site team will continue to monitor fox access to the wet grassland habitats, in order to protect the target bird species.
“Should monitoring reveal further predator access through the anti-predator fencing, the management team will consult with the Conservation Science Group and Conservation and Access Management Committee before considering whether lethal management interventions are in the best interests of the site objectives.”
The company has been asked how many foxes were killed in the cull.
The 400-acre Beddington Farmlands is a former sewage and landfill site that is now rich in biodiversity with more than 250 species of bird recorded.
It is currently being restored by Valencia, this was due to be completed by the end of this year but the project has been hit with delays.