Seagulls, at night?

What was up with the birds last night? It was almost scary the number of seagulls flying over our house after 10pm. And they were loud, we could hear them even while we were safely tucked in bed (out of the way of seagull droppings). Before falling asleep we asked ourselves: why are they flying at night? Where are they going?

Using Google this morning I came across mostly irrelevant pages on a Spanish horror film called "Night of the Seagulls" (which got poor reviews in case you were interested and doesn't seem to have anything to do with seagulls but instead involves zombie knights of some sort).

After trying a few better search terms (not involving "seagulls" and "night") I came across several pages explaining the migration habits of birds. The USGS has this publication here about when birds migrate which explains why they are flying at night.

So at least I know what they were up to now, althought I'm still not clear on where they were all headed.