For one, sophisticated UAVs that are much more capable than those the WWF is getting are already being used to combat rhino poaching. SANParks, the state agency responsible for South Africa's state-run national parks, has deployed the Seeker II military-spec UAV[0], ground radar, thermal imagers, cameras and dedicated teams of heavily armed rangers in the Kruger National Park, one of Africa's largest wildlife reserves. All anti-poaching resources have been placed under the command of Major General Johan Jooste, a highly-regarded retired military commander and a rewards program giving approximately US$ 10 000 to anybody whose tip-off results in the arrest of a poacher and about US$ 100 000 for a tip-off leading to the arrest of the head of a poaching syndicate has been created. At the same time the South African Army has deployed units in both the border patrol and anti-poaching role in certain parks.
These measures are all helping, but it's important to understand just what an impossible task this is. SANParks's 19 national parks alone cover 37 000 km², that's larger than Belgium, Israel, Lebanon and most US states. Moreover those 19 parks are dispersed across South Africa's 1.2 million km² and many of them are on the border of neighbouring countries from which many of these poachers come. It also doesn't include the hundreds of private wildlife reserves across the country which have been badly hit by rhino poaching. As the US has discovered on its southern border with Mexico, trying to prevent small bands of people from crossing a border this large is impossible even with UAVs, manned aircraft and massive resources.
So technology alone is not going to solve this, though it and other measures are hopefully going to help reduce the rate at which rhinos are being killed. The only long-term solution is to somehow stop the demand for rhino horn from Asia and thus remove the profit motive for poaching rhinos in the first place.
[0] The Seeker II is a 9-12 hour endurance UAV with all the standard surveillance gear such as FLIR cameras that is being provided free of charge by Denel, a South African arms manufacturer. The intention is to supplement that with a longer-ranged model, the Seeker 400, sometime next year. At the same time they're finalising development of a much smaller UAV, the Hungwe, that can be deployed by ranger teams for short-range surveillance.