katrin ludynia and her colleague collect data about the health of the birds.atrin ludynia: we tag the birds to get basically an id for each bird to see how long they survive. so we calculate survival of the species, because the species is decreasing dramatically, so the number are going down, and by seeing how often we're going to see the birds through the years, we can calculate what their survival rate is and what their chances are to survive in the wild. reporter: indirectly, tourism helps the penguins. visitors can take boat rides to dyer island. it used to be the biggest breeding ground for african penguins. in the 1970s, there were 25,000 breeding pairs here. but the population has shrunk dramatically. a long-term problem has been the harvesting of guano, the penguins used to make burrows in it. income from the boat trips helps fund a penguin and sea bird sanctuary at gansbaai on the mainland, with a rehabilitation centre for the injured and sick. xulani lawo: he's got a seal bite wound. and then now we've just cleaned , the wound. so he's going to be wi