Testable method! ♂♂ should exclude♀♀ sibs from helpers granaries!!! (over) Idea. nestlings Selfish ♂♂ are more valuable to other ♂♂ if helpers if Glen's Scrub Jay ideas are correct (♂♂ hang around longer, enlarge territory, etc) Parents should encourage equal treatment (equal investment) Perhaps why juv. plumage ID no sexual behavior characteristics (plumage or behavioral) until later. Weakness: Perhaps birds can sex each other in late juv or fledgling stage. How about ♂♂ at Plaque moving with imm. (1st year) bird of unk. Sex in late August. If it moults to ♀ hmm. (Perhaps nestlings do sexual recognition bit) Nestling "knows" its ♂♂ or ♀, can make choice to move. How testable. Also, most birds juv. can't be sexed. Probably worthless. ♀♀ Nestling should try to convince brothers that she is ♂ Kin Selection would call for equal treatment Walter has good data on why live in groups Now why + how much help Do all have stake in reproduction? certainly 1st year birds do not. How much help do others provide