Monarch Watch PreMigration Newsletter - July 2014
by Chip Taylor, Director, Monarch Watch
Those of you who follow monarchs closely are aware that the monarch population has been declining for the last 10 years with significant drops in the population each of the last three years. The number of trees and total area occupied by monarchs in the oyamel fir forests in Mexico was at an all time low last winter - a mere 0.67 hectares. This decline has given rise to a great deal of concern about the future of the monarch migration. These concerns have resulted in many meetings and plans, and even a Presidential Memorandum directing federal agencies to devote resources to offset the decline in monarchs and pollinators. We have addressed this issue through our Monarch Waystation, Bring Back the Monarchs and Milkweed Market programs. These programs are growing but they need to become much, much larger to sustain the monarch migration. Large-scale habitat restoration, particularly in the upper Midwest, also needs to become a priority. In the meantime, we need to keep tagging monarchs as a way of monitoring their numbers and tracking any shifts in the origins of monarchs that reach
Mexico. If you are a long-term tagger, you know it has been increasingly difficult to find enough monarchs to tag, especially during the last two years. The totals tagged each year roughly parallel the numbers recorded in Mexico each winter, giving us an independent assessment of the numbers in the migration. Regional tagging success also helps in that it demonstrates how monarchs respond to the physical conditions and quality of the habitats in these areas. Thus, tagging is an important tool to help us understand the overall dynamics of the monarch population.
So what should we expect this year? I usually like to wait until August to make predictions about the numbers in the migration and avoid bold assertions about the size of the overwintering population until well into the migration. However, this year I’m on record as early as the 3rd of May on our discussion list Dplex-L as predicting that there will be a modest increase in the number of monarchs in the migration and at the overwintering sites this winter. "Modest increase" is a vague term and I can’t put a number to it; however, all of the factors I’ve researched indicate that there will be more monarchs migrating this fall and at the overwintering locations by mid December when the colonies are measured. All in all things are looking up for monarchs this year.
Good luck with your tagging and thanks to all of you for participating in our program.
Please visit our website for a more detailed account of the current monarch population and updates as the season progresses:
Recording Tagging Data
• It is very important that participants record their complete name and contact information on each an every sheet . If you anticipate tagging more than 25 monarchs, fill in your name and address on the datasheet first and then make photocopies.
• When you record your data, use the complete six-symbol tag code. Without the complete code, tracking is virtually impossible. DO NOT USE the page number tags ; these are only on the sheet as a printing reference. Pages numbers are repeated each year and are meaningless.
• Use the datasheet example as a guide for the information to include on your tagging records. Be sure to record the tag code, date, and location (city, state, zip) for each tag you use.
Returning Your Datasheets Please, please, return your datasheets as soon as you are finished tagging for the season . Believe it or not, many people receive tags, tag monarchs, record data and then never return their datasheets. Every year the Monarch Watch staff spends countless hours (and a lot of money) contacting people who have recoveries but did not return their data. The data for a recovery is useless if we are unable to verify when, where, and by whom the butterfly was tagged.
Monarch Tag Recoveries
Most of the tagged monarchs recovered within the United States and Canada are found by people who know nothing about Monarch Watch or our tagging program. Email or voice communications about recovered tags usually include information on the location, date and circumstance of the recovery. If this information does not arrive with the tag report, we do our best to collect it. Once we have the tag code for a recovery, we search the tag database for that particular tag. If a record has not been returned, we must contact the person who received the tag. When we locate the datasheet for the recovered monarch, we record the participant’s name, along with the tagging location, date, monarch gender, etc., in the recovery database. We calculate distance according to latitude and longitude to obtain information for the straight-line course (a minimal estimate for the distance the monarch traveled).
Email us your data!
You now have the option of downloading a Monarch Watch Tagging Datasheet in spreadsheet format - to be filled out using Excel, Numbers, or another spreadsheet application. Once you have typed in your tagging data and saved the file, you can send it to us as an email attachment. Datasheets and complete instructions are available online at www.monarchwatch.org/tagging The majority of the recovered tags are obtained in Mexico. Early each year we visit the overwintering sites, particularly El Rosario and Sierra Chincua, where we purchase tags from the guides and ejido members. 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. We pay 50 pesos (about $5US) for each tag - reasonable compensation for the time and energy spent locating each tag. Part of the cost of the tagging kits covers these recoveries. However, in years in which there is high mortality at the overwintering sites the number of recoveries is high and exceeds the funds available to purchase tags. The Monarch Watch Tag Recovery Fund has been established to address the costs associated with tag recovery incurred by us each year. Contributions to this fund and to Monarch Watch in general are always welcome and appreciated: www.MonarchWatch.org/donate
What do we do with the data?
The recovery data is posted on our website and is analyzed to test hypotheses concerning monarch orientationand navigation. The data are also used to determine mortality during the migration and estimate the number of monarchs in the overwintering population. These analyses will be summarized on our website after the publication of articles.
When Does Tagging Begin?
As the length of daylight shortens in mid-August, monarchs in northern latitudes (i.e., near the Canadian border) begin to migrate. Monarchs farther south will begin their journey a few weeks later. Tagging and monitoring should begin in early to mid August north of 45N (Minneapolis) and late August at other locations north of 35N (Oklahoma City, Fort Smith, Memphis, Charlotte) and in September and early October in areas south of this latitude. For estimated peak monarch migration dates in your area please visit: www.monarchwatch.org/tagging
Capturing a Monarch
When in flight, monarchs are wary, elusive and difficult to catch. To maximize the number of monarchs collected for tagging, it's best to locate monarchs feeding on flowers or in roosts late in the day or early in the morning. With a butterfly net in hand, approach each butterfly slowly (from behind if possible), as sudden movement will startle it into flight. Sweep the net forward quickly and flip the end of the net bag over the net handle. You want the butterfly in the deep end of the net. With one hand holding the handle, use the other hand to collapse the end of the net bag. Flatten the net bag so the wings of the butterfly are closed over its back (thorax) and place thumb and forefinger over the leading edge of the wings (from outside of the net). Next, with the thumb and forefinger of your other hand, reach into the net and firmly grasp the thorax. Remove the butterfly for tagging.
You can purchase a good butterfly net directly from the Monarch Watch Shop (item# 120003; 1-800-780-9986 or Shop.MonarchWatch.org) or make one. The opening of the net should be 12” or more in diameter and the net bag should be at least 24” deep, allowing you to trap the butterflies in the end of the net without harming them. Net bags can be made from a variety of materials but it is advisable to choose see-through materials that won't rip easily as the net is swept over vegetation. The mesh should also be small enough thatthe monarchs aren’t able to wiggle free. Landing nets used by fisherman (available at most discount stores) can usually be converted to butterfly nets.
Storing Live Monarchs
If you collect more monarchs than you can tag immediately, you canstore them in paper triangles or glassine (#3 stamp) envelopes overnight or for a few days (no more than three). Simply place the envelopes in a plastic box or zip-lock bag in a refrigerator. A moist paper towel should be included to keep the butterflies from becoming dehydrated.
Once you become familiar with monarch adults, sexing is relatively easy. Males have an enlarged pouch midway along a vein that is directly below the discal cell on the hindwing see below). In species closely related to the monarch, this is a source of pheromones used in courtship. The pouches do not appear to be functional on the monarch. Females lack these pouches and appear to have thicker veins than males - this is actually only a difference in pigmentation. Upon close examination, you will also notice that males and females differ significantly in the anatomy at the tip of their abdomen.