| Please
Report Your Sightings! |
 |
Welcome to Journey North's 17th season! Three months ago, the first monarchs reached their winter home in Mexico after a long, fall migration. How many monarchs made it to Mexico — and how are the butterflies doing? This week, explore the population data scientists have just collected. Find out how scientists measure the size of the monarch population and what the data means for conservation.
This Week's Update Includes:
- News: Scientists Measure Monarch Population
- Slideshow & Guide: How Many Monarchs?
- Journal Page: How Many Millions?
- Seeing Monarchs or Milkweed? Report Now
- Research Question and Links: Explore!
 |
Photo: Dr. Lincoln Brower, Sweet Briar College
Population at an All-Time Low
The twelve major monarch butterfly sanctuaries in Mexico are measured
every winter. These yearly measurements give scientists a chance to estimate
the size of the entire migratory population. Scientists
announced the results in January. This year's population is the smallest
ever measured since monitoring began in 1994. Take a look:
| Area of Forest Covered by Butterflies | |
| Last
year 5.06 hectares* |
This
year 1.92 hectares* |
*One hectare equals 2.47 acres.
Did
You Know?
Although monarch butterflies are not an endangered species, their migration
is considered an endangered phenomenon. Scientists wait with
anticipation for the winter population estimates to be released every
year. Like a yearly check-up, the measurements indicate the overall
health of the migratory population. The number reflects survival and
reproductive success over the past year. Scientists
watch these numbers carefully and try to understand what causes changes
in the size of the monarch population.
What
Affects Survival? Look for Factors!
As you study monarchs with Journey North this winter and spring, focus
on the theme of survival. What threats do you think monarchs face at
the overwintering sites in Mexico? What challenges will they face during
spring migration? Next spring and summer, what will affect the monarch's
ability to survive and reproduce? Taken together, factors throughout
the monarch's annual cycle will affect the size of the next winter's
population. Challenge yourself to identify factors
that affect the monarch population size, just as scientists are doing.
Bar
Graph
Monarch Population in Mexico
1994 - present
Monarch
Butterflies!
One bough can hold 15,000 monarch butterflies
Map
Mexico's Monarch Butterfly Wintering Region
Slideshow
Look at a monarch colony from the air and imagine counting millions of
monarch butterflies. Take a walk into the forest and see how scientists
actually measure the monarch colonies!
- Slideshow: How Many Monarchs This Winter?
Teacher
Guide
This
new Teacher Guide provides a framework for exploring monarch population
data from Mexico. Students use actual data from current research. They
investigate how scientists use the data to reflect on past events, assess
current trends, and make predictions for the future. The activities put
this year's population data into perspective and help students see why
monarch population studies are so important.
- Teacher Guide: How Many Monarchs This Winter?
How many millions of monarch butterflies are in a monarch colony? For almost twenty years scientists used an estimate of 10 million monarchs per hectare. Then something happened.
- Read the Story! Find out what caused scientists to raise their estimate to as high as 50 million monarchs per hectare.
- Write in Your Journal: Estimate how many millions of monarch butterflies are in Mexico this winter.
Journal
Page
How many millions of monarch butterflies?
All monarchs do not go to Mexico! Please help us document where monarchs are located this winter, and whether milkweed is available.
This
Week's Research Question:
Why do scientists often say they don't really know how many monarch butterflies
are at the overwintering sites in Mexico?
Explore these links to do your research:
- Story: How 10 Million Became 50 Million
- Journal Page: How Many Millions of Monarch Butterflies?
Additional links to explore:
- Monarch Math: How many football fields would this year's monarchs cover?
- Pie Chart: Where Are the Butterflies This Winter?
- Pie Chart: Which Sanctuaries Do Monarch Butterflies Select? Compare Two Seasons
- Journal Cover & Pages: Monarch Winter Habitat Journal
- Overview: About Journey North's Monarch Butterfly Overwintering Study
- Get Ready to Track Spring Migration: How to Watch for Monarchs
The Next Monarch Migration Update Will Be Posted on February 11, 2010.
© 1997 – 2019 Journey North. All rights reserved.
