The plum-headed and blossom-headed parakeets can be confusing at first. There are quite a few photos and videos marked incorrectly which I guess is due to that fact that plum-headed(Psittacula cyanocephala) was sometimes known by the name of blossom-headed parakeet. But blossom-headed is now used to refer only to Psittacula roseata. Lets us look at the main points that can clear up the confusion.
Head&Neck Color: The plum-headed parakeet’s head is deep read nearing maroon. The hind parts of the head is a deep purple-blue i.e. just like a plum. The neck below the black neck band is a different color from the rest of the body – it is a greenish-blue. The blossom-headed parakeet on the hand has a very pale pink head, Its hind head is marked by a very pale ,almost whitish blue. The neck below the black neck ring is same green as the rest of the body.
Dear friend, I hope these roses placed side by side will help you remember how differently their heads are colored. The first for the male plum-headed parakeet’s head color and the second for the male blossom-headed parakeets head color.
Range: The blossom-headed parakeet is a bird of the North-East India, beyond into other countries east of India like Myanmar,Laos,Cambodia,Thailand etc.So if you see a pale pinkish headed parakeet, in North-Eastern India,well, it is the blossom head. The plum-headed parakeets are present in other parts of India but absent in North-East.
Tail Tip Color: Both the male and female plum-headed parakeets have a very long, very noticeable white tip to their blue tails. The blossom-heads have a small yellow tip to their tails.
Shoulder patch for females: The plum-headed parakeet female has no shoulder patch. The blossom-headed female parakeet looks very similar to the counterpart but it has a shoulder patch present just like the male’s shoulder patch.
The diagrams below helps you visualize some of the tips listed above, with reference to the birds.
Photo Courtesy of michaelandhelencox
Photo Courtesy of Vijay Anand Ismavel
These are two excellent videos which will clarify once and for all what the blossom-headed parakeets look like.
Blossom-headed parakeet at Nehru Zoological Park Hyderabad
Blossom-headed parakeet Vietnam
Checkout great images at this link from oriental bird images
Plum-headed parakeet page @ Wikipedia
Blossom-headed parakeet page @ Wikipedia
Plum-headed parakeet page @ World Parrot Trust
Blossom-headed parakeet page @ World Parrot Trust