The wind rustles through a reed bed in Hout Bay, the bass line to the warbling of birds. Standing very still, Garret Skead looks around and identifies more than a dozen bird species by sight or by their calls.“The habitat is a clue,” he says, reeling off names. “Then you evaluate the major features to make an identification. It’s like a diagnosis.”

Skead is a pathologist who spends his free time searching for rare birds and recording these sightings on the app BirdLasser. He is among a legion of “citizen scientists” in SA who observe flora and fauna and enter the information into biodiversity apps, helping to paint a picture of the country’s species and where they are at risk...