Viva! campaigner Justin Kerswell said it would push the Co-op to go beyond adopting the standard.
The supermarket announced it would comply with Freedom Foods on 20 May, following a 'national day of action' on which Viva! organised around 200 demonstrations outside Co-op stores nationwide.
'The Freedom Foods standards are essentially factory farming standards and the Co-op has not said it would go over to selling free-range duck,' said Kerswell.
Viva! is set to hold further protests within the next two months, and intends to distribute leaflets and ask questions at the Co-op's regionally organised AGMs.
The group will write to every Co-op store manager asking them not to sell factory-farmed duck.
It will target wildlife, women's and men's magazines with features on the subject, and offer national newspapers covertly filmed footage of conditions on factory duck farms. Celebrities such as Sir Paul McCartney and Joanna Lumley are endorsing the campaign.
A Co-op spokeswoman said it had 'only received about a dozen' calls from the media about the protests.