Flags at the U.S./ Mexican border

Chasing monarchs in anticipation of catching the migration’s leading edge, Carol Cullar, director of the Rio Bravo Nature Center, traveled about Maverick County near Eagle Pass, Texas.

“These winds this year are acting like a spigot turned off and on. Past years have consisted of long, continuous streamers of monarchs persisting for days from the same direction, down the same corridor. Rather than a daily flow, we're getting dribs and drabs. This could be the briefest monarch passage we've had in years.”

• Carol Cullar's Observations in Texas: Fall 2007