The breeding success of remaining
birds in Southeast Asia appears
to be low ( Timmins & Ou Ratanak
2001). Uncontrolled hunting has led
to wholesale population collapses of
wild ungulates in this region (Srikosamatara
& Suteethorn 1995; Duckworth
et al
.
1999; Hilton-Taylor 2000)
that, together with changes in husbandry
of domestic stock (Cambodian
Wetland Team 2001), have resulted
in a huge reduction in the
carrion available for vultures. It
seems likely that food supplies are
no longer predictable enough to allow
regular breeding. Persecution of
vultures when they are gorged on
carcasses and at nests may also have
played a role ( Thewlis et al
.
1998).
Persecution may be at a level that
makes birds shy enough to be affected
by incidental disturbance (authors’
unpublished data), and, given
the high human density across much
of the region, this factor should not
be underestimated. Habitat loss, except
insofar as it has contributed to
ungulate declines, can be discounted
as anything other than a local threat
( Thewlis et al
.
1998 ). The role of
agrochemicals remains unclear;
there is no persuasive indication that
they can explain region-wide losses
in Southeast Asia, although they
may have caused local declines (Cheke
1972).