Monarch Facts

Even with over 50 years of tagging data, monarch mysteries remain. How do the Monarchs find the overwintering sites each year when they are several generations descended from last winter’s overwintering insects? Exactly how does their homing system work, especially when they are blown off course? Their journey to Mexico is like a 6 foot tall human circling the globe 11 times in a row!

How long do the butterflies live? – Monarchs live from 2-4 weeks depending on environmental conditions. Overwintering Monarchs can live up to 8 or 9 months!

What happens to them after the butterflies are tagged and released? – Monarchs have the ability to travel thousands of miles. They can find small patches of milkweed (the caterpillar food plant) hundreds of miles away, stopping to nectar on plants in the wild and in people’s back yards! Monarchs released in the fall will migrate to various over-wintering sites, returning the following year. After their release, monarch butterflies will continue on with their lifecycle, helping to pollinate our Island flora before traveling about 1,600 miles to the overwintering site in Mexico.

Do they stay around after the release? – Yes! Monarchs are very “friendly” butterflies. They aren’t preyed upon by most butterfly predators because their bodies contain toxins that are distasteful. They are fearless when they interact with people and will allow you to move in close to get a photograph and sometimes even let you pick them up.

How is the Data collected – The majority of the tags recovered are obtained in Mexico. Early each year Monarch Watch personnel visit the overwintering sites, particularly El Rosario and Sierra Chincua, where they purchase tags from the guides and Mexican people. The ratio of untagged to tagged Monarchs is quite high and it takes most residents several hours to find each tag among the butterflies visiting sites along streams or dead butterflies on the trails and under the Monarch-covered trees. They pay 50 pesos (about $7-8) for each tag – reasonable compensation for the time and energy spent locating each tag.

What do they do with the data? – The recovery data is posted on Monarch Watch’s website and is analysed to test hypotheses concerning Monarch orientation and navigation. The data are also used to determine mortality during the migration and estimate the number of Monarchs in the overwintering population.  Once they have the tag code for a recovery they search the tag database for that particular tag.  When they locate the datasheet for the recovered Monarch, they record the participant’s name, along with the tagging location, date, Monarch gender, etc., in the recovery database. They calculate distance according to latitude and longitude to obtain information for the straight-line course (a minimal estimate for the distance the Monarch traveled). The recovery is available as soon as it is entered and both the tagger and the person who recovered the tag can view the records online.