The flocks are thought to originate from a handful of birds which escaped in 1969Researchers in Kent believe flocks of wild parakeets have been migrating to the West Midlands from London.
Wild, green ring-necked parakeet populations are already well-established in the south east.
Researchers based at the University of Kent have now conducted DNA analysis of feathers found in Sandwell.
They said the parakeets were genetically very close to their southern counterparts, which originate from India.
Chris Edwards, from the RSPB, said eight birds had been seen in the Sandwell Valley nature reserve this year.
The breed is thought to have moved into the area in 2009.
Hazel Jackson, a PhD student at the university, said the parakeets in Sandwell could be supplemented by a few escaped pet birds, but feathers found in the area suggested they shared a common ancestry with the London flock.
She added that about 32,000 green ring-necked parakeets were now thought to live in the UK, mainly around the south East.
The species, not native to Britain, is believed to have been founded from just a few escaped pet birds in 1969.
Ms Jackson said there were also a few common rumours about their origins.
"One of them is that they escaped from the set of The African Queen, which was filmed in London.
"The second theory was that Jimi Hendrix released them into Carnaby Street to inject some psychedelic colour into the UK."
Researchers said the parakeets had been able to adapt to the British climate and had flourished because of their ability to feed on a wide range of foods.
For the same reason the flocks could also pose an increasing problem to farmers.
Analysis
Dr David Gregory Environment correspondent, BBC News
The key to this new research is to be able to DNA test live parakeets living in the wild. In an ideal world you would take a blood or tissue sample and extract the DNA from that. Sadly wild parakeets are not terribly cooperative if you start towards them with a syringe so you need an alternative.
In this case the researchers used feathers from moulting birds that have been gathered from the ground.
Now you can't extract any useful DNA from the feathers themselves. But about halfway along the shaft of the feather you'll find a tiny blood spot. It's just about visible with the naked eye and while not ideal it does yield just enough DNA to allow researchers to do their work.