Well, "also as per normal demons" would seem to hint at tanar'ri traits, if not the subtype.
Okay, so we're doing an Evil Outsider bird-man chemosit/geteit first, and then do the Nandi bear/hyena version, which could be treated as a particularly nasty Magical Beast?
Going by the write-up it's a very minor demon, no nastier than a Dretch. It doesn't even have any resistance to mundane weapons!
I don't think it's a Tanar'ri, just one of the innumerable other CE creatures that go bump in the night.
Some of its stats seem pretty obvious:
Medium sized Outsider (Evil, Chaotic), but is it Extraplanar or Natural. Presumably Extraplanar if it really is a demon.
For 'demon defences" I suppose a Dretch's are a good start - Special Qualities: Damage reduction 5/cold iron or good, darkvision 60 ft., immunity to electricity and poison, resistance to acid 10, cold 10 and fire 10, plus throw in spell resistance of 12 or so for the original's 10% MR. Might toss out the immunity to electricity.
I'm tempted to give it at-will
flare as a Spell-Like Ability, so it can use its "shining mouth" to dazzle its victims, plus maybe some other light-power.
Its 2-7 damage claw and 1-6 damage bite suggests the claw is its primary attack.
Do we give it a full attack of bite or claw like the original, or bite
and claw? I'd prefer bite and claw, it's got little enough going for it as it is.
Now, what ability scores to give it? I'm thinking something around a gargoyle's stats and mental stats, except with a good Dex and average-ish Con and a Dretch's 11 Charisma rather than a gargoyle's 7. I imagine it as an agile but not exceptionally tough flier. That works out about:
Str 14, Dex 16, Con 14, Int 7, Wis 11, Cha 11
Not spectacular, it's definitely near the bottom of the demonic pecking order.