Durian flesh isn't toxic and some parrots enjoy it, but it's very high in fat and sugar (and famously pungent), so it's a small, occasional treat at most. Remove the large seeds.
Keeper's noteA small piece of ripe durian flesh occasionally is fine for birds that like it. Remove seeds, and don't make it a staple given how rich it is.
What to watch out for with durian
Durian's creamy flesh is non-toxic and brings some vitamins, but it's unusually rich — high in both fat and sugar compared with most fruit — so it's easy to overdo. The big seeds should be removed, and the smell, while harmless, is divisive. This is a flagged entry given limited avian data.
How to serve it
Ripe flesh in small amounts; remove the seeds.
An occasional treat, not a regular food — it's very rich.