STRATEGIES FOR LAND-BIRD CONSERVATION ON MAURITIUS

The native wildlife of Mauritius is highly threatened by a variety of influences other than habitat destruction. Protection from habitat des truction atone cannot guarantee its conservation and the damage alread y sustained is not fully reversible Therefore, the ideal for conservat ion-maintenance or restoration of self-sustaining populations of all s pecies in native ecosystems-is presently unattainable. We assessed thr ee long-term strategies for maintaining and increasing populations of threatened native birds on the mainland and offshore islets of Mauriti us, with respect to efficacy, sustainability, and side-effects. Rehabi litation of native vegetation on the mainland is likely to improve foo d availability over limited areas, but it can only form the basis of a long-term bird conservation strategy when population density of intro duced animals, especially predators, can he reduced sustainably, at lo w financial cost, and without adversely affecting native wildlife. Mar ooning bird populations on ecologically rehabilitated islets can elimi nate the predator problem, but they would be vulnerable to catastrophe s (especially cyclones) and possibly disease and much habitat manage m ent work is still needed. A third novel strategy-enhancement of mainla nd habitat using exotic plants-allows creation of source habitats, gre atly reducing the predator threat. It also permits larger areas to be managed and at lower cost, than is the case with intensive rehabilitat ion. Habitat management regimes for conservation of threatened species or communities must be designed specifically to alleviate population- limiting factors. Ln altered environments certain exotic plants can be essential to the survival of native animal species. The most effectiv e conservation measure must not be assumed always to be the rehabilita tion of native vegetation.