Monarchs: time to expand our milkweed patch!!

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One of the key indicators of health for North America are the Monarch butterflies that come back each spring.

2012 was a lousy year for them.Herbicides are probably a major problem, but they face lots of challenges besides Roundup. The Monarch  has large orange and black wings. The Monarch prefers Milkweed as a host plant. For nectar, it feeds on such plants as Milkweed, Aster, Cosmos, Daisy, Red Clover, and Zinnia.

For us in the vineyard, the quantity of Monarchs is an indicator of the quality of the vintage.

Western monarchs reach British Columbia only in summers with extended periods of warm, sunny weather in the Pacific northwest.

The CBC Says:

http://www.cbc.ca/news/technology/story/2013/03/20/f-monarch-butterfly.html

Soulsby Farm shows what they are doing:

http://soulsbyfarm.org/2013/03/24/build-a-monarch-rest-stop-waystation-butterfly-garden/

PATTERNS:

In a monarch butterfly’s life cycle, it goes through a complete metamorphosis involving four stages: egg, larva (or caterpillar), pupa, and adult. In addition, each individual monarch contributes to a larger population life cycle, involving many generations. The fall migrants are usually 3 or more generations removed from the monarchs that overwintered in Mexico during the previous winter. In other words, each fall the last generation of monarchs must navigate to a location, perhaps 2000 miles away, which they’ve never visited.

The majority of monarchs who make the fall journey are in reproductive dormancy. The goal of this initial population is to survive the trip to the overwintering sites in Mexico. After their season in the migratory site, the female monarch reproductive organs become fully developed and mating takes place.

As they migrate north in the spring, they lay eggs on milkweed along the way. These larvae appear in the southern return path in March and early April. This generation will also migrate North following their parents. The reproductive cycle continues and by August to early September, three to four generations will have evolved. So losses which have occured througout themigration cycle will be replenished by this population buildup.

It would be nearly impossible for an individual monarch butterfly to complete this entire migratory cycle. Because of this, their rapid system of reproduction is of great importance to the survival of the species and the completion of the migratory cycle from year to year.

III. Migrational Pattern/ Behavior:

The migration of the monarch butterfly begins in Canada and the northernmost parts of the United States. The fall migration begins in late August ending in the months of November and December. The destination of the butterflies lies in Central Mexico, in the Oyamel forests. Traveling in a southwesterly direction, the monarchs fly east of the Great Lakes and south-southwest in areas west of the Great Lakes. Those that reach the gulf of Mexico follow the coastline in a continuous stream. They continue in a southwest direction eventually reaching the overwintering site in the Transvolcanic Plateau of Mexico. As many as 300 million spend the winter there.

During the migration, monarchs encounter many dangers. These dangers include such things as storms, predators, humans (more accurately, their cars), and simple fatigue. Many butterflies are the casualties of storms and are eaten by birds. Hundreds are crushed by cars crossing the highways, and still many more can be seen limply trying to keep aflight, ready to collapse at any moment. Even after the monarchs arrive at their winter retreats, the danger of storms is still a major factor on the survival. The danger is greater, particularly in Mexico, where temperatures, strong winds, and snow kill thousands.

As mentioned before, this migration takes up to three generations to complete! The exact migratory path is still being plotted today. Scientists are tagging the butterflies, and recording their locations during the months of the fall migration.

During the migration, the monarchs feed extensively on flowers to gain carbohydrates from nectars which fuel daily activities and contribute to the build up of the fat body in the abdomen. This fat supply gives energy to the monarchs on their long journey. Monarchs travel distances as great as 3,100 miles during their migration, traveling roughly 50 miles per day. Monarch flight speeds have been measured at 12 miles per hour. Once they have reached their roosting site, they cluster in large numbers in the branches and trunks of the oyamel trees. While clustering they remain quiescent (they stay relatively sill and maintain low metabolic rates). In mid-February, the monarchs at the roost sites become more active and mating behavior begins. By the end of February, some of the monarchs begin moving northward, by mid-March the roost is usually depleted (Urquhart1987).

This initiates the start of the spring migration. The spring migration starts out with only about half of the original roosting population. Forty to sixty percent of the monarchs die during their stay in Mexico. During the spring migration, the monarch butterflies return to their homes in Canada and the northern most parts of the United States. Along the way, they roost and reproduce, giving rise to new butterflies that will continue the spring flight back.

IV. Migration Mysteries:

Now that the details about the actual migration process of the monarch butterfly has been covered, a common question that most people wonder about is why the monarch butterflies migrate in the first place? Unfortunately, there is no one simple answer to this question. Researchers in this field are collecting field data related to the monarch’s biological migratory behavior to try to uncover this mystery. Although there are no definite answers to the question of why monarchs migrate, several hypotheses have been formulated.

The first and most simple explanation is that like migratory birds, monarch butterflies migrate to warmer climates to escape from the upcoming cold weather and the food shortage that will result from the temperature fall. But how do the butterflies “know ” that the winters are cold? They don’t. What the monarch butterflies sense is the changing amount of light present and the variability of day and nighttime temperatures. With the change of seasons from fall to winter comes the inevitable shortening of the days, longer nights, and also colder nighttime temperatures. Once these characteristics show up, the monarchs leave for their overwintering sites.

The question now is: Why do the monarchs follow such a particular flight pattern and destination? In his book the Monarch Butterfly: International Traveler, entomologist Fred A. Urquhart addresses this issue, and developed a hypothesis based on his studies of monarch butterflies. Mr. Urquhart states that migration is related to three principle factors: (1) monarch larvae feed exclusively on species of milkweed; (2) the migratory pattern is from northeast to southwest; and (3) there is a long history, extending over eons of time, of the distribution of the milkweed species of the genus Asclepias (p.119).

The conclusion is that, ” the northwesterly-southwesterly migrations are correlated with the changing distribution of the species Asclepias resulting from changes in the North American land mass over millions of years.” (Urquhart 1987) In plain terms, the migrational pattern presently observed originated in the distant past when the monarchs were following the milkweed species which were spreading westward. This east-west movement was eventually incorporated into the monarch’s genetic code to produce a cyclical migration related to some as yet unknown response to seasonal changes on the planet.

PACIFIC COAST

There is a distinct population for the pacific coast, west of the Rockies.

The western population includes all monarchs found west of the Rocky Mountains in the United States and Canada. The current annual breeding range of western monarchs extends from Arizona and New Mexico to southern British Columbia and from the Rocky Mountains westward to the Pacific coast. Western monarchs reach British Columbia only in summers with extended periods of warm, sunny weather in the Pacific northwest. During such favourable years, breeding occurs in scattered locations across the province, particularly in the Okanagan Valley and along the Fraser River.

Monarchs of the western population undertake an annual migration much like that of the eastern population. They overwinter at numerous sites along the nearly 1 000 kilometres of the California coast to the Mexican border. More than 200 overwintering sites have been recorded in California, and individual colonies may support dozens to tens of thousands of individuals. The vast majority of these overwintering sites are associated with stands of non-native Australian eucalyptus trees.

The annual southward migration of the eastern and western monarch populations begins in Canada in early August and continues through to mid-October. When monarchs are migrating, they do not reproduce. They avidly seek nectar from flowers to fuel their migration and to build up a critical fat reserve to sustain them through the winter. This stored fat is also essential for their northward migration in the spring, when nectar sources are not available.

The Central American monarch population occurs in Guatemala, El Salvador, Honduras, Belize, Nicaragua, Costa Rica, Panama, and southern Mexico. Unlike the eastern and western populations, the Central American population migrates only 10 to 100 km between highland and lowland areas, according to dry and wet seasonal conditions. This monarch population reproduces throughout the year.

 

FOODS

Butterfly season generally starts in April and goes through October. When planning your butterfly garden, choose a variety of plants that will bloom at different times throughout these months. If everything blooms in the spring, your butterflies will pack up and move on by summer.

A standard butterfly garden includes a mix of annuals, perennials, herbs and shrubs. Plants that are considered butterfly friendly include: Alyssum, Anise, Aster, Bee Balm, Butterfly Bush, Butterfly Weed, Catnip, Chives, Clover, Columbine, Coreopsis, Cornflower, Cosmos, Day Lily, Delphinium, Dianthus, Digitalis (Foxglove), Dill, Echinacea (Purple Coneflower), Fennel, Honeysuckle, Hollyhock, Impatiens, Lavender, Lilac, Lobelia, Lupine, Marigold, Milkweed, Mint, Nasturtium, Parsley, Petunia, Phlox, Queen Anne’s Lace, Salvia, Sage, Shasta Daisy, Snapdragon, Sunflower, Sweet Peas, Sweet William, Thistle, Trumpet Vine, Verbena, Veronica, Yarrow, Zinnia.

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