Right off the bat, they realized the birds were all migratory species, which would put them in the airspace over the Gulf twice a year. In the spring, many birds fly north from the Carribean, Central America, and South America to spend warm summers nesting in North America. Come fall, they make the return trip, often with new offspring in tow. To cross-reference the timing of when birds should be flying over the Gulf with when bird remains ended up in shark stomachs, the team used the citizen science database eBird, where users log birds they encounter from day to day. Lo and behold, tiger sharks ate the most birds in early September, right at the start of the fall migratory period.