What is the main reason Tule geese took longer to migrate in 2020?

• A. Airborne pollutants
• B. Strong tailwinds
• C. Lack of food
• D. Increased daylight

Answer: (A)

Air quality and visibility can shape how quickly birds migrate. In 2020, widespread wildfire smoke and other pollutants created poor air conditions, making flight more energetically costly and harder to navigate. The smoke can force birds to fly at different altitudes, rest more, or take detours to avoid dense plumes, all of which lengthen the journey. By contrast, strong tailwinds would typically speed travel, increased daylight can provide more flying time, and a lack of food would slow foraging and energy but wouldn’t inherently explain the widespread delay caused by polluted air. So the primary factor behind the longer migration is airborne pollutants.