you can't know that!
these sites are only created to get some traffic and earn money from that. so whenever they can't find anything they just create stories about supposed "whales" moving bitcoins around where in reality they are just looking at the blockchain and listing the biggest transactions and attaching a story to that so that they can keep their traffic up!

there is no such thing as "whale alert". most whales don't even store all their coins in one place anyways. and they definitely don't use a single exchange for huge amounts such as 1 million bitcoin!!!