AG210 was tagged on Monday morning, September 22 at 9:22 a.m. at the Canelo Forest Service Administration Area in southeast Arizona. She was a freshly eclosed female spotted in the field feeding deeply on thistle. This is the farthest north in California any of our Arizona monarchs have been ever recovered so far. We estimate AG210 flew 680 miles in 34 days or approximately 20 miles per day. We don't know the migration route of this monarch. We do know that Dr. Fred Urquhart and the Monarch Program both noted that monarchs tend to fly north once they reach the California coast. There is more to learn.
The monarch migration is guided by an internal sun-compensated compass. As they fly, they adjust their flight to the angle of the noon day sun. In the eastern migration, Dr. Chip Taylor of Monarch Watch (pers. comm.) observed that the leading edge of the monarch migration begins in Winnipeg, Ottawa (45.42°N latitude) in Canada when the sun angle is 57° to 56°. Through monitoring monarchs that are tagged when freshly eclosed from milkweed fields in southeastern Arizona and later recovered along the California coast in early September, the Southwest Monarch Study is finding that the migration from southeast Arizona appears to begin earlier. Here is a chart of our recoveries to date from September 7 to November 19. The red Xs are monarchs tagged in southeast Arizona that were later seen along the California coast. The bold red X is AG210 that was just recovered by Jessica with a sun angle at the time of tagging of 58.49°. The blue Xs represent tagged monarchs that flew to Mexico. Sun angle at the time of tagging for all Southwest Monarch Study recoveries range from 66.16° to 39.22°.
So what determines migration destination from Arizona? Is it sun angle or something more? Once again wind direction during the week after tagging may play a role. We will continue to review all these factors.