Perhaps - The feds already have confirmed biological, chemical and/or nuclear insurgency risks.

IE, they believe that there is a high likelihood of high casualty events, and of course the region around NYC is the prime target because it has Atlantic access and is highest population in the US.

So these things are super duper flying labs equipped with the broadest possible spectrum of instruments and testing devices. They may be sampling the air, taking infrared and LIDAR readings, etc. A very broad range of tests may account for the size of these things.

For example, spectroscopy of the air would probably require heavy equipment. A biological screening may require air sample gathering and cultures and then analyzing any growth.

And it would have to be a broad spectrum of tests like I say in order for such a drone to return usable results.

And of course there is no info because of public panic reaction.