WHAT KIND OF BIRD CHIRPS AT NIGHT - ONE QUICK CHIRP EVERY 30 SECONDS OR SO?

There are many birds that will call at night. Without knowing even what part of the world a bird is from it's impossible to give you a list of potential species. Depending on the time of year & part of the world, some of the sounds people mistake for birds at night are actually insects or small amphibians.

http://www.allaboutbirds.org/page.aspx?pid=1059

The invasive European starling that migrated here. It's a really small ugly black bird, about the size of a robin. You can put a toy plastic owl out there. Get it at Menards. But you might have crow problems all night.

Gluck.