Rosy starlings are a species of migratory bird, which comes into Gujarat in the late winter early part of summers. I think they are a native of the temperate regions of Asia, but come down south for a few months.
I noticed rosy starlings from among the different birds which abound near my house because they have a distinctive behavior. Every evening, they settle down near some shedding tree and keep making a huge noise. The din is positively deafening but it serves to attract many more of their species to join them on the trees. Finally, when they seem to attain a quorum (I dont really know, I am just interpreting their behavior), they become silent for a second and then fly away en masse. The birds flying away in a group is truly a sight to savor. The increasing noise as they gather, the momentary calm, and then the sudden scary sight of a huge number of birds flying together in formation. If you watch them from my terrace, which is quite close to the tree they congregate in, you will almost jump back in fear, since it is almost like they are attacking you. And then they will go and find another tree nearby and create a ruckus for some more time and then repeat the pattern.
I dont really know why they do it. If I try to interpret their behavior anthropomorphically, it seems like a roll call for the day or perhaps signing out of work or something. But I doubt if birds have those concepts. I dont know enough about them to understand whether they choose specific groups to get together in or just get into the nearest available gathering. I dont know who initiates the group. I just like to watch them everyday because they are a delight to watch. They mark time for me in the evenings. And they make me realize that the exotic is within my reach. I dont need to go on trips to new places to enjoy stuff all the time (although that is also useful). I can still be at home and have loads of stuff to enjoy as well.
Here is a video of the rosy starlings from our terrace. Watch for the mark at 1 min 25 seconds, that is when they begin to fly away. It is quite scary!!