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The Monarch Butterfly Annual Migration

Decent Essays

Introduction
The monarch butterfly annual migration is a visually spectacular feat, in terms of the number of butterflies flying to their overwintering sites and as well as the masses that congregates at the overwintering sites in Mexico. The idea that monarch butterflies exhibited migratory behavior was once controversial, it was not until Fred Urquhart and his colleagues pioneered a tagging work with the eastern North American population for decades that revealed the long distance of the monarch migration. The tagging efforts that began in 1937 lead to the discovery of their overwintering sites in Mexico in 1975. With its long distance traveled and the nature of the predictable and the repetitive nature of its annual migration. The …show more content…

Environmental factors such as the decrease in day length, cooler temperature and aging milkweed trigger the monarch to begin its migration, although the precise environmental trigger that initiates migration is not well understood. When spring arrives, they become reproductively active, mate and leave Mexico to re-migrate north. During the remigration northward the females lay fertilized eggs on newly emerged milkweeds in the southern parts of the United States (Reppert and others 2010). Their offspring’s will also continue the migration up northward to repopulate the northern section of the monarch habitat range. Even though the monarch migration is repetitive and cyclic in nature, their migration cycle is multigenerational. It takes about two generations of spring and summer butterflies that are following the progressive northward emergence of milkweeds to repopulate the entire range and therefore completing the migration cycle (Reppert and others 2010).

Time-Compensated Sun Compass (The Navigational process)
The Monarch butterfly uses a map and a compass like other long distance migrants. The map sense is needed to determine which direction they are to fly and to stop. The compass sense is utilized so that the migrants can orient in the southern direction throughout the course of their migration. It has been shown that the monarch may not have a true map sense, although the monarch

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