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.
Butterfly
Nets
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.
Sexing
Monarchs
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.
