Once noted for its abundance of mammals,
there is now a notable lack of large mammals in the park. The decline of
widlife in the area is due, in large part, to the construction of roads,
which allowed easy access to once-remote areas.
Nevertheless, there are still a large
number of small mammals living in the forests of Doi Inthanon, and
it is quite possible that larger animals, such as bears, occasionally
pass through the park.
In the winter of 1994, a leopard
cat (Felis bangalensis) took up residence in the swamp at the summit,
and many visitors walking along the nature trail there were able to enjoy
watching it hunt bards and roddents.
Fishing cats (Felis vivenina)
inhabit the areas along the many streams and rivers in the park.
Barking deer (Muntiacus muntjak)
and sainber deer (Cervus unicolor) are common, and a keen eye can
see marks on tree trunks where they have rubbed their horns.
Wild pig (Sus scrofa) and feral
buffalo (Bubalus) also haunt the forests, leaving their marks in the
soil.
Serrow still inhabit the more
remote areas of the park, and gibbons occasionally visit Vachiratarn
waterfall at dusk, filling the air with their calls.
Macaques are known to inhabit
the forests behind Mae Ya Waterfall.
Flying squirrels glide about
the trees behind the fire station at dusk. There are also about 30 species
of bats flying at night.

Far more impressive than the mammalian
life, however, is the avian diversity of Doi Inthanon. About 400
species of bird can be found on the mountain in the winter season,
almost half of all the species found in Thailand! Doi Inthanon is an extremely
important wintering spot for many migratory bird species that come from
Mongolia, Siberia, India, Nepal, and many other places. Two species
- the Ashy-throated warbler and the Chestnut-headed minla - are
found nowhere else in the world, and a beautiful race of Green tailed
Sunbird is also unique to the mountain top.
