All 1HD humanoids in the monster books are considered to be 1st level warriors, why on earth they gave the kobold only half a HD is beyond me. Also 1HD planetouched are considered being 1st level warriors, as well as 1HD monstrous humanoids.
Some ECL's of 1 HD humanoids/monstrous humanoids:
Aarakocra: +1
Drow: +2
Goblin: +0
Hobgoblin: +0 (some belive it should have an ECL of +1, but I hardly think it's more powerful than the common half-orc or human.)
Kobold: +0
Orc: +0
Later,