Fall is the critical food-gathering time for monarchs for three important reasons--the three seasons of fall, winter and spring:
Gaining Weight for Winters' Five-month Fast:
This graph shows how much energy monarchs have, as stored fat, each month of the year. Notice how little is stored in the summer and how much this changes during the fall! At the overwintering sites in Mexico, very little nectar is eaten by the butterflies, if any. The overwintering period is like a 5-month weight-loss diet. Monarchs must survive all winter on the fat they accumulate during the fall. And, they must have enough energy left to fly back north in the spring.
So Busy Eating You Can Sneak Up and Grab One
Butterfly behavior changes noticeably in the fall as the importance of feeding increases, notes Dr. Lincoln Brower:
"If you try to catch a butterfly between your thumb and forefinger in the summertime you'll have a very, very hard time catching it. But they are so intently nectaring [during fall migration] that you can actually, if you're really careful, sneak up with your thumb and forefinger and just grab one. If they've had a good feed their stomachs will actually be fat. (See photo.) They feed on that [nectar], and the nectar has sugar in it. They convert that sugar into fat and that fat is the energy store that they use to fly down to Texas and then on into Mexico."
Monarch Morphology: The Proboscis
Each plant or animal has different structures that serve different functions in growth, survival, reproduction. (K-4)
Living systems at all levels of organization demonstrate the complementary nature of structure and function. (5-8)
The behavior of individual organisms is influenced by internal cues (such as hunger) and by external cues (such as a change in the environment). (K-4)
Behavior is one kind of response an organism can make to an internal or environmental stimulus. (5-8)
National Math Standards