Parrotlet aggression

Question
I have two parrotlets (both female around 1 year old).  One is very passive (green) the other assertive (blue).  The assertive one has become very aggressive in the past 2 weeks.  She lunges and bites me and is now starting to bite the passive parrotlet.  Nothing has changed in our routine.  They have a large cage and are let out in a large room for the day (up at 8am to bed at 7pm).  They willingly go in and out of the cage.  The aggressive one is chewing on the door frame, lunges at me, lands on me and bites, and goes after the other parrotlet if she comes near her or me.

I am not sure what has gotten into the blue parrotlet?  Not sure what to do?

Answer
--  Separate them immediately.  

--  Sometimes these things happen and we never really find out why.  I've recently seen two gorgeous, big Hyacinth's resort to ill will toward each other after more than 15 years of harmony.

-- In some cases you've got an influx of hormones in one bird and they have no idea what to do with it themselves.  It's sort of like what humans call "roid rage" - when a male has an overabundence of steroids in his system leading to easy temper outbursts and anger.

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It could also be that the cage is too small for two.   It can all seem great for years sometimes and then suddenly the pressure and stress is too much and one (or both) birds begin acting out violently, aggressively.

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 A proper sized cage would mean that BOTH birds, at the same time, can full open their wings AND completely turn around, while on the same perch .... and not have any part of their body touch each other or any part of the cage.

When I explain this to people their first reaction is usually "Ohhh... heck, even ONE bird can't do that in the cage I have"

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Find out more here and steps you can start implementing right away

       http://www.4animalcare.org/birds