The monarch's winter habitat in Mexico is surprisingly cold. Temperatures can fall to freezing! This week, explore how the cool winter habitat meets the monarchs' needs for survival. Also, Estela Romero reports from Angangueo on the anniversary of last year's deadly landslides.

This Week's Update Includes:

• News: A Critical Time is Passing
• Slideshow: Temperature and Survival
• Journal: Monitor Temperatures of Monarch Habitat
• Life in the Monarch Region: Estela Romero Reports
• Seeing Monarchs or Milkweed? Please Report Now

News: A Critical Time is Passing

It's almost mid-February. This mean the monarchs have now survived what's typically the coldest part of the overwintering season. "The really critical time for the monarchs is January and early February," says Dr. Lincoln Brower. Temperatures can fall so low the butterflies can freeze to death.

Dr. Brower has studied the monarch's overwintering biology in Mexico since the 1970s. "Right now we are waiting to hear how many monarch butterflies are overwintering in Mexico," says Brower. "World Wildlife Fund-Mexico usually releases their annual report in early January, after they have measured all the areas in December. These data are crucial to understanding the annual size of the eastern monarch population."

How large will this year's population be? Dr. Chip Taylor of Monarch Watch estimates 5-6 hectares. This graph shows measurements made over 16 years. Notice: Last year's population was the smallest ever recorded. This year's results are expected any day and will be provided here. What do you predict? Will the population be above or below average?

Average Low Temperatures

How many monarchs in Mexico this winter?

It can be warm during the day at the monarch's winter home in Mexico, but at night it's as cold as the inside of your refrigerator. This is surprising! Why do monarchs migrate long distances to overwinter in a place that is so cold? Explore this week's slideshow and resources:

• Slideshow: Temperature and Survival
  Includes Photo Gallery, Booklet, Text-only Version, and Teacher's Guide with:
  • Pre-reading Anticipation Guide
  • Risks and Benefits Chart
  • Blank Book for Student Writing

Slideshow
Temperature and Survival

Last Friday was the first anniversary of the deadly landslides that struck Angangueo on February 4, 2010. Estela Romero shares her town's experience as they mourned loss and celebrated survival.

"One year ago we suffered the worst tragedy in the history of our town ever imagined by any of us living here. We had a long religious ceremony and totally crowded procession remembering the children and adults who died one year ago and visiting the points in town most affected by the disaster. I hope the images give you at least an impression of what we lived today." 

• Noticias de México por Estela Romero
• News from Mexico by Estela Romero

Monarchs were also part of this procession. Our Monarch was wearing a black and white ribbon on his upper right wing, in signal of grief, like the rest of the people.