Monarch Migration Update: Febuary 16, 2012
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The monarch's winter habitat is surprisingly cold. It often drops below freezing. Why do monarchs migrate to such a cold place? This week, explore the temperatures monarchs need to survive. Also, meet the young tour guides Estela met at El Rosario Sanctuary.

This Week's Update Includes:

Image of the Week
Monarch Butterfly Sanctuary Video Clip
News: Cold, Wet Weather Continues
Estela Romero reports from the monarch overwintering region:

"We continue to have terribly rainy, gray, cold days! The sanctuaries are practically without tourists. Last weekend, with a little rain and soft hail falling, I went up to the sanctuary to conduct an interview for you. I hope you enjoy seeing how some local people work with the monarchs!"

Warming Soon?
This graph shows average low temperatures at the overwinering sites. Now that it's mid-February, monarchs have survived what's typically the coldest part of the winter season.

"The really critical time for the monarchs is January and early February," says Dr. Lincoln Brower. "The lethal combination for the butterflies is to be wetted by a winter storm, and then subjected to freezing temperatures caused by intense radiant heat loss when the sky clears."

Counting Cold Fronts
The 34th cold front of the season entered Mexico this week. How can cold fronts affect overwintering monarchs? They can bring cold, polar air masses into central Mexico. Cold air, interacting with moisture from the Pacific, often results in sub-freezing temperatures, wind, hail, snow and ice in the butterfly colonies. Meteorologists predict Mexico will have 50 cold fronts this season. Watch the weather maps. How many more fronts will reach the monarch region?

Risks and Benefits?
This picture reveals clues about ways cold can affect monarchs. Why are so many on the ground? Are they in danger? This week, learn about the risks monarchs face—and the benefits they receive—from their cold winter habitat.

Monarch butterfly sanctuary tour.
Photo: Estela Romero
Meet the Tour Guides
Graph of annual temperature in the monarch region
Adapted from L.P. Brower
Warmer Soon?
Weather Map
Image: SMN

Counting Cold Fronts

Monarch butterflies in sanctuary in Mexico
Image: Dr. Lincoln P. Brower
Risks and Benefits?
Slideshow: Temperature and Survival
Why do monarchs migrate long distances to overwinter in a place that is so cold? This week's slideshow explore's a key question:

Essential Question
What temperatures do overwintering monarchs need to survive?

Journal page

Journal: Monitor Temperatures of Monarch Habitat

How are temperatures affecting monarchs today? You can track real-time weather information at the monarch overwintering region. Keep a journal of temperature conditions in Mexico and compare them to your own:

Weather in Mexico

Data Sheet Journal page for data analysis Sentence starters for data analysis: Gray whale migration data



The Migration: Maps and Journal Page
Before spring migration begins, please help document where monarchs are being found and where milkweed is available.
Monarch Butterfly Winter Sightings Map of milkweed emergence: Spring 2011 Map of monarch wintering sites in Mexico
Monarch Sanctuaries
First Monarch
(map | animation | sightings)
First Milkweed
(map | animation | sightings)
The next monarch migration update will be posted on February 23, 2012.