Pedant alert!

Squirrels live in a dray - it's what their nests are called. I think I can see where you got dray from, but that particular list is from people's submissions (just google collective nouns or check Wikipediment) - there's no such thing as a 'dropping of pigeons' - that's just bad grammar for pigeon poop. And never in all my life connected with dairy farming have I ever come across a 'flink of cows'....

People have heard about the dray in connection with squirrels and just put the two together. A family of squirrels may live in a dray, but it's not called a dray of squirrels.

Neither is it a lounge of lizards but that one is rather funny.

LTS