Better news for Stewart Island's dotterels

Forest and Bird, Issue 268, 1 May 1993, Page 4

Better news for Stewart Island's dotterels

John Dowding

THE CAT-CONTROL programme designed to protect the highly endangered New Zealand dotterel population on Stewart Island (see Forest & Bird November 1992) has just completed its pilot season. Feral cats are the main threat to the birds, the only remaining members of the species breeding south of Hawke Bay. Last October about 200 bait stations were set up enclosing an area of about 2.5 sq km around Table Hill, and the baits and birds were checked each month through the season. By mid-February, all birds from the protected area had left the breeding grounds and moved to their coastal wintering flocks. The results from the full annual census of the population

in April are not yet available but preliminary surveys of the Mason Bay and Awarua Bay flocks in late February suggested that the baiting has been successful and cat predation reduced. Autumn counts at both sites had declined steadily since 1990 but there has now been a rise in the total population for the first time since the study began. A conservative figure for the 1993 population is currently about 70 birds, up from 62 at the same time last year. The programme was sponsored by Software Education Associates with additional funds from the DoC/Forest and Bird Threatened Species Trust. Although the result is very encouraging, there are still problems. There is a serious shortage of male birds in the population — males do most of the nest incubation at night and seem to be more at risk from the nocturnal attentions of feral cats. Two more males were

lost on Table Hill this season, almost certainly because the programme started a month too late. Nests were already present when we arrived in early October and the two males disappeared before bait stations could be installed. Also because of the acute shortage of males, some fe-male-female pairs are forming and laying clutches of infertile egos. On the positive side, our experience this season suggests we can make significant improvements in future baiting strategy. In the wet conditions on Table Hill, most of the catbaits went mouldy within two months; by modifying the way baits are prepared and by changing them more often we can improve protection of the area with little extra effort. Timing can also be improved; the loss of two males early this season was a serious set-back, but something we should be able to avoid in

future. If the programme is carried out next season, we must make sure that baits are installed at least a month earlier. This should help significantly, by removing any resident cats well before the birds begin nesting. Indications from the 199293 season are therefore very positive and it is now important to keep up the momentum. The trial programme needs to continue for three to five years for two reasons. First, there will be natural annual fluctuations in dotterel survival and productivity, depending on weather, cat density and so on. We need to know whether the population can be maintained and increased successfully in the longer term, through these fluctuations. Second, we need to know whether there is significant recruitment in the protected area — will the young birds being produced now return to breed on Table Hill when they are two years old? If not, a few other key breeding sites on the island may need to be protected as well. Stewart Island’s dotterels still have a long way to go, but at least there’s some hope. With a technique available which promises help, it is important now to put the whole pro- gramme on a more secure footing.