Birds are VERY posessive of their homes ( their cage ) &
will display aggression to anyone or anything they see as a
threat.
My advise to you ( esp. since this is an older bird & you
apparently don't have much experience/knowledge of birds in
general, as yet ) is to get on your computer & locate all of
the information that you can about this spacific type of
Amazon Parrot. There are books available ( look on
amazon.com ) on caring for Amazon Parrots as well as dealing
with a re-homed bird. You will find that all birds have
different types of personalities & possibably problems, due
to being owned/bonded to a human who just up & disappeared
from their lifes. Birds don't understand the death/loss of
their owner. All they know is that they have been up-rooted
from their safe ( human ) home & moved to a new location &
now have strangers providing their food, water, etc.
So you really need to read, read & read some more & educate
yourself on how to take proper care of this bird, if you plan
on keeping him/her. Because parrots can live for a Very Long
time ( like 50 - 70 years! ) if taken proper care of. You
can't rely on any internet chatboard to give you all of the
information you are going to need to properly care for this
bird. And I speak from 1st hand knowledge, because I adopted
a 7 year old Green Cheek Amazon Parrot 5 years ago & had to
take a crash course ( I was in my late 40's at the time ) in
caring for a bird! I have since bought several books on bird
care & printed so much information off the internet that I
have a notebook full of information. And have tons of links
to bird related information saved in my favorites list. So I
know the stress & trials of taking on a grown/mature bird.
And believe me, it takes a whole lot longer than a few weeks
to bond with an Amazon Parrot! It can take months ( & even
years in the case of a bird who has been abused or moved from
one home to another. )
There is a company in Florida called Avian Biotec ( do a
google search ) that does DNA sexing of birds from blood or
feathers. And by now they may also be doing it via a beck
swab ( I know they where working on that several years ago ).
There is no longer a need to put a bird thru that horriable
surgery to sex them & frankly if a vet told me that was the
only sure way to do it, I'd be finding another vet
posthaste! All of the information you need on that matter
can be found on their website.
And lastly be sure to locate at least one good Avian Vet in
your area. We have several vets where I live, but NONE of
them care for birds ( besides nail & beak trimming ). When
our bird fell ill 3 years ago I had to drive over 100 miles
one way, just to get to an Avian Vet. Which was a lot of fun
during the winter!
Hope this information helps to get you started on your way
to being a good parrot-parent!
Wishing you well with your new family member!
Bird Mom