purpose of lengthy immature plumages

[Gary Wright <>]

I was watching doco on Patagonia and it was mentioned that Condors take five
years to get adult plumage and I wondered why.  I thought of an Australian
species like Pacific Gull which also takes five years? to get adult plumage
and checked in HANZAB but couldn't find anything relevant to why.  Reasons I
could think of why any bird would take so long to get adult plumage were:
1.  long learning process to be independent
2. shortage of territories
3.social organisation being subordinate to dominant adults/cooperative
breeding

I don't think any of these apply to Pacific Gulls.(don't know anything about
Condors)  Can anyone shed some light on the reasons for such a lengthy
period of immature plumage and I assume lengthy period before breeding?

Gary
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