I think you mean a hide. It's to allow good views of birds without disturbing them.
BirdWatchers was created in 2008.
The duration of BirdWatchers is 1.73 hours.
Newsletter for Birdwatchers was created in 1960.
Birds go tweet. And twitters is shorter and catchier than birdwatcher.
The cast of Birdwatchers - 2011 includes: Humberto Castello as Conquistador 2
They are called lairs, dens, burrows or earths.
A "Twitcher" or more properly an "Ornithologist".
An otter's den is called a holt or a couch.
So that they have somewhere to live and to raise their kits.
den
It is called a lair, a den, a burrow or an earth.
A bird-watcher's den is called a HIDE.