They were "introduced" unintentionally (but entirely forseeable) in the late 70's when they were fore sale at a tenner at large warehouses, brought in from India and central Afrika. Of course they made far too much noise, and what must have seemed a nice present to one of your children, was soon something to get rid off. Being the seventies (you know, hippies and freedom for all and return to nature) quite a few people simply let them out into "the wild". For years, only a few pairs survived, but from halfway into the 90's the newborns made themselves at home and slowly colonies started to form.
They are viewed as a pest now, with the colonies growing steadily in the cities, where they have found a way to survive and breed. But I see it a little different, they did not ask to be brought over here after all, and not being a migratory bird, they had no way to get back to Afrika, let alone India. So I sort of admire their successful effort to make a life for themselves in our cities and parks. There must be around 10.000 now in Holland, 28.000 in Belgium! I have seen their slow but steady ascent, culminating in having one visit a tree nearby recently. They sleep in large groups, and often you can witness their activity of assembling for the night. Their colors obviously are ill matched with our environment and with other birds. They will never be a real pest though, because their breeding success remains limited, but for sure they are here to stay.
B.t.w. these images were about the first from my new combo: Z7+500PF+1.4TC, but today I tried the Z7+500PF (bare) out, and that combo really impresses me. There are a lot of good things to say about it. I really like the clarity of IQ and consistency of auto focus. Nikon must have come some ways from firmware 1.0 to version 3.0, because if the AF is truly hopeless, I am just not seeing it. The Z7 nails it with the 500PF, no hunting and hardly any variation, mostly all spot-on. The only downside really, is that the lens does not always travel straight to the plane of focus, but sometimes travels beyond, turns back one or two times, and then hits focus. That happens very quickly, but it is annoying, and if Nikon can get that out, than it really is starting to impress. Just travel to the plane of focus, land there and fire the shutter, that is how it should be consistently. I would love to see Matthew try one out, just to hear his impressions. I know he did not like the EOS-R, and felt he could not pin point small birds in amongst the braches, but the Z7 sure does in my experience.
Also very nice is the FF coverage with ability to move your focus point around left to right, up and down, and it works with the same spot-on AF right into the corners. The joystick is great, it is so easy to place the AF point anywhere you like.
I also like the EVF a lot. I always hated the Sony A7RII's EVF, which is like a little crappy tv screen (I still use that body with the Loxias!). The EOS-R's EVF was also nice, but the Z7's EVF somehow is so clear and natural, that I can see the subjects better than throught the D500's OVF. What also had me sceptical, was the experience with the A7RII's (efcs) shutter, which is sluggish and just not a high framerate shutter. The Z7's shutter is great, very soft, no slap of any kind, but not at all sluggish, just quick and lean. I tried out Hi+, and was amazed being used to the Hi framerate mode of the Sony A7RII.
I can now finally use the VR "normal" mode, which is hardly useable with the D500, apparently due to the vibration from the shutter/mirror assembly. With the Z7, I can easily go down to 1/200s with VR normal.
The ergonomics and build quality are also so much better and nicer than those of the the Sony A7RII.
I hope Nikon will get a few more firmware updates out before dropping support for the Z7! All in all, I think it is a great body.
Very interesting background on the Parakeets. I've heard a similar story regarding the origin of the Monk Parakeets I mentioned. They are similar in many ways to what you described.
I'm with you on the "no fault of their own" situation.
When I was 1st switching from Canon to Nikon (I had already bought a D500 & 200-500 for my wife & played enough with it to understand the D500 AF capabilities), I had sold all my Canon gear and was at the store making my initial transition purchase I had a D850 on my list. They were out of D850's at the time, but my buddy at the store slid the 1st Z7 "in north Texas" in from of me and assurred me that it was everything the D850 was "and then some". Not knowing anything about the Z bodies and eager to get new gear in my hands, I accepted the Z7. Along with it was a D500 for me, a bunch of lenses, and various accessories.
As I began acclimating to my new gear, when I began testing the Z7 I was shocked to discover that not "everything the D850 was", let alone the "and then some" part. Because I had a particular set of expectations, I returned the Z7 for a D850.
Months later, the Z6 came out & I picked one up with a different set of expectations. I have enjoyed the Z6 since day one, even with v1 firmware. It has gotten progressively better with each release and I expect that to continue. Had I gotten the Z7 w/o having had my expectations set erroneously high, I'm sure I'd love it too.
I'm not sure why, but the Z50 is quicker to focus than the Z6 even with the latest FW. Perhaps its due to the sensor size or logic. One of my regular shooting buddies has both the Z6 & recently added Z50 and he echoed the same experience with the Z50 AF.
As I've said many times, it sure is nice to drop a TC (1.4x, 1.7x, 2x) on with virtually any lens and the Z body just performs - no AF Adjust / AFMA required. 
) putting up with my belly aching over this past winter. 
