Credit: Aron Hejdström, CAnMove Swifts aren't called "swifts" for nothing. They're known for being among the fastest migrating small birds around. When they aren't breeding, common swifts stay in the air most of the time--up to 10 months of the year. Scientists had thought they travel about 500 kilometers per day on average. Now, new evidence reported in the journal iScience on May 20 shows that's a conservative estimate. According to new tracking data, common swifts travel 570 kilometers (more than 350 miles) on an average day--but they are capable of going much farther and faster. The maximum recorded distance in the study was more than 830 kilometers (more than 500 miles) per day over nine days.