untitled

The changes in the macropod fauna included the extinction of six species and the

decline of 23 species, of which two died out completely on the mainland but still

occur in Tasmania. The rates of decline are often difficult to estimate because the

year in which the decline began is seldom known and indices of population size are

seldom available. Land clearing and extensive sheep farming were in full swing in

Australia by 1840 and declines in macropods were evident by the late 1800s. Many

of the declines followed sweeping changes to habitat as land was cleared for agri-

culture or grazing by sheep modified the vegetation. The smaller macropods (<5 kg)

were the most affected, only one species (Macropus greyi) of the larger macropods

going extinct. Calaby and Grigg (1989) emphasized the difficulty of determining the

cause of declines retrospectively but considered that the evidence strongly suggested

that the declines of nine species could be referred to the effects of land clearing, nine

to modification of vegetation by sheep, five to introduced predators (foxes and cats),

and seven to unknown causes.

The sheep grazing and woodland clearing that led to the decline or extinction of

at least 17 species concomitantly benefited five species of the larger macropods, which

increased in numbers. A further four large macropods and four of the 11 species of

the smaller rock-wallaby (Petrogale) have changed little in numbers from the time

of the European settlement to the present day.

The Mundanthurai sanctuary in southern India was classified as a tiger reserve in

1988. Tigers (Panthera tigris) live in dense vegetation with access to water, but are
      restricted to core areas of protected reserves and avoid areas frequented by humans.
      Since 1988 cattle have been removed and fires controlled so that a dense vegetation
      of exotic Lantana camaraand other species unpalatable to wild ungulates has grown
      up. Consequently the large ungulate species that comprise the food of tiger, and that
      require grassland, have declined. Both tigers and leopards (P.pardus) have declined
      with their food supply in the reserve (Ramakrishnan et al. 1999).

The Lord Howe woodhen

The Lord Howe woodhen (Tricholimnas sylvestris) is a rail about the size of a

chicken. It lives on the 25 km^2 Lord Howe Island in the southwest Pacific, 700 km

off the coast of Australia. Lord Howe was one of the few Pacific islands, and the only

high one, that was not discovered by Polynesians, Melanesians, or Micronesians before

European contact, and which therefore suffered none of the man-induced extinctions

common on Pacific islands over the first millennium AD. Humans set foot on it for

the first time in 1788, at which time it hosted 13 species of land birds of which nine

became extinct over the next 70 years or so.

The story of the Lord Howe woodhen is related by Hutton (1991, 1998). The island

was visited regularly for food (which no doubt included woodhen) and water by

sailing ships in the late eighteenth and early nineteenth centuries, and finally settled

permanently in 1834. Pigs were introduced before 1839, dogs and cats before 1845,

domestic goats before 1851, and the black rat (Rattus rattus) in 1918 from a ship-

wreck. By 1853 the woodhen’s range was restricted to the mountainous parts of the

island, and by 1920 its range had apparently contracted to the summit plateau

(25 ha) of Mt Gower, a 825 m (2700 ft) mountain almost surrounded by near ver-

tical cliffs rising out of the sea. The summit plateau is a dreary place: dripping moss

forest and perpetual cloud, a rather different place from the coastal flats that used to

CONSERVATION IN PRACTICE 315

18.2.2The effect of
loss of food

18.2.3The effect of
introduced predators