You always need to be wary of loafing birds around an airport that a shooed away from one runway only to set down near another. It's pretty damn difficlut to move birds completely off an airfield in a single day. Runway activity is your friend, as the birds don't feel welcome. Inactivity for over 30 minutes when bird shooing is ongoing somewhere else on the airfield is your worst risk. There goes ONA at JFK where they asked to use an inactive runway and nobody cleared it beforehand. Other similar examples