Wildlife of Lao PDR: 1999 Status Report - IUCN

Wildlife of Lao PDR: 1999 Status Report
Under “Other countries recorded”, where a species has been recorded widely across a country, no specific area is given in parentheses.
The areas (e.g. Vietnam: W Tonkin) follow those defined in King et al. (1975) and Robson (in prep.). Cambodia has not been regionally
subdivided by these authors.
*Chiang Saen lies on the Mekong in NW Thailand directly opposite Lao PDR and there records quoted here were of birds by or on the
Mekong River, which forms the Lao-Thai border. Not all species with such records are known to the authors.
the status of some species listed here as ‘Seasonal status unclear’.
The assessment given relates to any or all of Lao PDR.
It does not imply that the species is of uniform seasonal occurrence
throughout the country. Where seasonality is suspected
to vary across the country, this is indicated. Further
work will undoubtedly reveal many more species with complex
patterns of seasonal occurrence.
Some species, most or all of which breed, visit Lao PDR
only during the wet season (approximately May - October).
Early arrivals of most of these species turn up in March, in
the last few weeks of the dry season.
Passage migrants are individual birds which neither breed
nor winter in Lao PDR. With resident species and those which
visit Lao PDR to breed or to winter, it is often unclear if
substantial numbers of passage migrants also occur. Birds
which appear during migration in areas where they do not
winter may not be passage migrants in the national sense, as
they may have wintered or bred elsewhere in Lao PDR. However,
the Annamites are a major migration route for many
Palaearctic species wintering in Indochina and south-east
Thailand, and so many species are probably numerous as true
passage migrants. In the following list, bird species are specifically
noted as passage migrants only when numbers are
markedly greater during migration (for most northern visitors,
September - November and March - May) than during
winter (roughly November - March). Stopover migrants frequently
occur in habitats and at altitudes outside the species’s
usual wintering grounds.
The term ‘vagrant’ implies that the species is outside its
usual range. It is applied only to few species, where records
from neighbouring countries suggest that the Lao records truly
were unusual events. Many of the other species known in
Lao PDR by only a single or a few records may in fact be
regular visitors (e.g. the pulse of waders recorded on the southern
Mekong during the only spring it has been surveyed;
Evans et al. in prep. a) and many others are clearly likely to
be resident (e.g. various woodpeckers). Observation has not
yet been sufficient to allow clear understanding of their status,
but to categorise species as vagrants simply on the basis
of the small number of records to date would be misleading.
Breeding status across Lao PDR is often unclear. Small
birds that occur throughout the year are likely to breed. Wideranging
large birds (e.g. storks and vultures) may be present
in Lao PDR in all months merely as non-breeders.
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Habitats and Altitudes
Habitats used in Lao PDR by each species are assigned
to simple categories (see Introduction). King et al. (1975)
listed habitats used by each species across its South-east Asian
range, and in the absence of information specific to Lao PDR,
these were used in the first edition of the present work (Salter
1993b). They are left unchanged here only when adjudged to
reflect accurately the species’s actual habitat use in Lao PDR.
As habitat use often varies across a species’s range, every
attempt is made to present information specific to Lao PDR.
If there is no information from Lao PDR, this is stated, and
in some cases a predictive habitat is given, usually derived
from adjacent parts of Thailand, Cambodia and Vietnam.
Altitudes are sometimes given descriptively (e.g. ‘lowlands’),
but for many species a quantified range is given, based
on recent survey information. This is not intended to be a
predictive range outside of which the species should be considered
unusual, but merely to lay a baseline to stimulate
more attention to altitudinal zonation in Lao PDR. Most species
for which no altitudinal information is given are largely
passage migrants, many of which may occur at almost any
altitude. For others, e.g. some large owls, there are simply
not enough records for anything meaningful to be said. Many
species occur at lower altitudes in Lao PDR, especially in
evergreen habitats, than in the more westerly parts of their
range. This trend continues east into Vietnam (C. R. Robson
verbally 1998). Even within Lao PDR, many bird species
use lower altitudes in the east than in the west. Also within
Lao PDR, there is a tendency for hill species to occur at lower
altitudes in areas of limestone karst than they do in noncalcareous
forests.
Key Species of Special Conservation Significance
Key species (those of special conservation significance)
are bulletted (•). Global status information is from Birds to
watch 2: the world list of threatened birds (Collar et al. 1994).
Globally Threatened species are listed (in increasing order
of threat) as Vulnerable, Endangered and Critical (see Conventions).
Globally Near-Threatened species are not yet believed
to be Globally Threatened. A Red Data Book specifically
for Asian birds is currently in preparation by BirdLife
International and some of the status assessments of Collar et
al. (1994) are expected to change. However, proposed new
assessments are not incorporated here as their citation prior
to finalisation by BirdLife might lead to later confusion.