Media planning agency Trinity Communications was briefed to plan and implement the campaign to complement WWF's existing direct marketing activity.
The aim of the campaign is to acquire new legacy supporters. The legacy scheme allows people to leave a gift to the WWF in their will as a legacy for the future.
Trinity will test inserts, created by Tangible Response, across national press supplements and magazines to find out the quickest and most effective messaging, targeting and route to market.
One of the inserts features colour images of a range of endangered species with bold text asking "Could you choose a future without one of these?"
Sarah Cunningham, legacy marketing manager at WWF UK, said: "To help us acquire new supporters we're keen to look at a number of new media channels and we believe that the first initiatives from Trinity give us an opportunity to reach a far wider audience of potential new donors."
Phil Nunn, partner at Trinity Communications, said: "Our approach to WWF's acquisition brief went beyond marketing to their existing database and instead used a targeted approach to bring in supporters through cold lead generation methods thus expanding the potential roll out for legacy giving as a growing part of the WWF fundraising portfolio."