I closed my server to double check the length of my seasons; when I opened the server again (less than a minute or two later) the smallish tallbird I had hatched immediately aggroed onto me upon spawning in, and wouldn't stop trying to attack me. I originally thought it was because they had grown into a normal tallbird, but they were still a smallish tallbird, and I was still able to offer seeds for food (although they wouldn't take it and immediately attacked the second I got close enough). They had not been aggressive immediately before I disconnected.
Active Server Mods: Global Positions; Mineable Gems; Multi Rocks; No Thermal Stone Durability; Show Me (Origin); Simple Health Bar DST; Recipe Randomizer
Active Client Mods: ActionQueue RB2; Combined Status; Geometric Placement; Minimap HUD
I rolled the server back and grabbed this clip from respawning in https://va.media.tumblr.com/tumblr_qsb8p3YJNC1z1f0gq_720.mp4
Sorry if I'm missing any details, my brain is so scattered tonight
1. Set Spawn Area to "Plus"
2. Character Wortox, Have mods active (not sure if either are required/the reason??)
3. Hatch Tallbird Egg provided in chests at spawn
4. Day 24 (should have smallish tallbird by now), disconnect from server.
5. Launch server again.
6. Smallish tallbird should aggro towards player.