I personally believe that aggression is absolutely something you can modify. We've discussed a lot of the tools to do that in this forum in different places.
I think a male may just be "bolder" than a female...not necessarily aggressive. They are quicker to approach while hens may tend more towards "follow the leader". Of course, I'm just speaking of tendencies, not about individual birds because that will vary greatly.
I don't have serious incompatibility issues with my flock....Hens (TAG, CAG, Senegal) Males (Senegals)....however, this is probably more due to my perceptions and how I husband them. Bailey does get chased by all of the other birds....but since he is flighted it is not a huge, big deal. He has learned where to go (top of the get-a-grip) to stay safe. His biggest problem is that every time he finds an object that he is intensely interested in playing with....somebody else invariably decides THEY want it and they will chase him away from his toys. As far as aggression goes, Babylon WILL go after him if he is in his cage so I don't leave him in his cage when she is out unless I am right there to run interference. She does not chase him all of the time. Mostly, she's doing her thing and every once in a while, she gets a wild hair and decides to fly over and act aggressive with Bailey......but she will also do this to me on occassion if she's in a bad mood....so it's just something I work with and work to modify.
Here is how I do the math: In a flock, if one parrot is most aggressive, I would prefer that is the smallest bird. Bigger birds need to be taught that it is okay to defend themselves but they also need to be highly reinforced for gentle behavior. Beak sparring is okay. You don't want a bird that bites to kill. You need to be working with that bird from day one to constantly be reinforcing gentle behavior....but some of that will be dependent on personality of the bird.
Since you will have two birds, you will find that flock dynamics are also somewhat reinforcing so most parrots will at least show initial interest in each other. Greys have a "monkey see, monkey do" tendency. Your grey will probably copy some of what Kili does. This will be very subtle and you may not notice it, but greys study EVERY THING and one day you will see the evidence of it.
My hens are gentler than my boys. The hens do seem more inclined to nips rather than quick, fast bites; however, I am working with Senegals. Also, and this is a big factor, my boys are all rehomes. They came to me as adults with past histories so I did not have the chance to modify behaviors when they were young. Also, I'm not sure that greys are naturally fast, hard biters. I am absolutely sure that greys are really easy to buy into the culture that you set up for them. Especially if you start with a baby. Baby greys are just little learning "sponges". They are different from Senegals because Senegals think quick, pretty much make up their minds and you work with them from there.
I really think that people who have biting problems with greys created those problems. It is really easy to modify that sort of behavior with a grey. I really doubt that you will have a problem with your baby grey no matter what sex you choose. I think you might have some issues with Kili because she may feel a little jealous. You will have to work carefully with her so that she doesn't feel threatened by the attention that you give to the new bird.
If Kili picks on the new bird, then you might have some retaliation issues. This is going to be a problem no matter what sex you choose....(My Kiri lived with a caique that used to sneak up behind her and pull her tail. It was a problem because Kiri would plot to trap the caique in her cage and was pretty intent on doing damage to the smaller bird....Fortunately, my senegals are not that bold and they have the sense not to push Kiri that far.)
You aren't going to cage your birds together. You will also let them each have their own space. You may not have any issues at all....
Just some thoughts!
Mona in Seattle
Phinneous Fowl (aka Phinney) TAG
Doug (spousal unit)
Jack and Bailey (Gremlins)
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