Searched and only found a listing of ingredients. From what animal/where can pine thrush eggs be harvested? Are they harvestable(sp) at all? I have been crashing around in pine trees looking for pine thrush nests for a bit now...

Whoops, sorry, didn't realize this should be in the spoiler side. Must be more to it than just finding nests, I suppose.

Found on the ground. Nests are built from needles under pines.

1. Find pines.
2. Search the ground. They're quite easy to spot, akin to a chicken nest seen near homes and farms.
3. I usually find 3-4 in one area.

I initially found some WSW of Riverwood whilst trekking toward Falkreath.
Hope that helps.

Aha! I have been searching the trees at ~ eye level. Didn't think to look on the ground. Thank you!

Glad to help.
However, don't stop looking up!
If you see one pass, or see its shadow pass by on the ground around you, follow that hawk!
Easy source for two useful ingredients. Don't waste arrows; just plunk them when they land.

Spoiler within a spoiler thread:
_{Hawk Feather + Mudcrab Chitin = Cure Disease potion.}

Thanks! I have seen the shadows moving across the landscape but I'm apparently looking too slowly or in the wrong direction to spot them. I'll manage!

There's only one I remember finding randomly,despite having two in my inventory,it was just sitting on a ledge in some random dungeon. So inspect everything,even if they look like slightly too round rocks...