Alabama Butterfly Atlas

Monarchs are the most celebrated and well-known butterflies in North America.  They are familiar residents of Alabama and occur in every county.  Yet, because of their migratory patterns, most Alabamians encounter them only in spring and fall when they pass through the state on the way to and from their wintering grounds.

Monarchs are reliant on poisonous food plants called milkweeds.  These plants contain chemicals (cardenolides and cardiac glycosides) that taste bitter and cause congestive heart failure in vertebrates. Monarch caterpillars can ingest these chemicals, retain them in their bodies throughout metamorphosis, and use them for their own defense.  Birds find them very distasteful and learn to avoid black, yellow, and white striped caterpillars as well as orange and black butterflies. 

Monarchs are not cold tolerant but eastern populations solve that problem by migrating to a warmer climate—a feat that involves flying thousands of miles and circumnavigating a continent.  Monarchs that originate as far north as Canada and New England follow the Appalachian Mountain range south, and some eventually stream through Alabama.  Many make it to south Alabama where they roost communally in trees and shrubs in places like Fort Morgan and the grounds of the Grand Hotel in Fairhope. Most travel on to Mexico, but new research indicates that there may be an additional migration route that moves some east through coastal Alabama and then south to south Florida and the Caribbean.  In 2008/2009, Duane Miller discovered that hundreds stay in Alabama, clustered in pine trees at Fort Morgan, flying only when days are warm.  

Monarchs are well-known and widespread, but the species has been plagued with problems.  In central Mexico, primary wintering grounds have been threatened by logging.  In this country, crucial milkweed-rich habitat has been lost due to changes in agricultural practices and general loss of habitat.

Another big threat to long-term abundance is microscopically small: a protozoan parasite called OE (Ophryocystis elektroscirrha) infects butterflies that host on milkweed.  The parasite weakens caterpillars and cripples adult butterflies. OE must live within a host to grow and multiply. However, when it is not inside a host, OE survives in the environment as spores, which are resistant to extreme conditions. These tiny spores are sandwiched in between the scales that cover the butterfly’s body. Spores are much smaller than wing scales; a monarch scale is about 100 times larger than an OE spore. Infected females pass on the parasite to their offspring when they lay eggs by inadvertently scattering spores on their eggs and the surrounding milkweed. When a caterpillar hatches, it not only eats its eggshell and the milkweed, but also the OE spores. Once eaten, the dormant spores move into the caterpillar's midgut. During digestion, the spores break open and release the parasites. Most of the damage done to the butterfly happens during the chrysalis stage, where the parasites multiply exponentially. About three days before the adult emerges from the pupa, spores will begin to form, which allow OE to survive outside of the monarch’s body. The spores can be seen as dark patches that appear through the outside layer of the chrysalis. Infected adults emerge covered with spores. Once butterflies are infected, they do not recover. By the time adults emerge with parasite spores, all physical damage by the OE parasites has been done – the parasites do not grow or reproduce on the adults. The spores are inactive or dormant until they are eaten by another caterpillar. According to researchers at the University of Georgia, Monarchs that do not migrate are more likely to be infected.  It remains to be seen how changes in climate as well as widespread availability of non-native milkweeds in the landscape will impact long term Monarch health.

VOLUNTEER OPPORTUNITIES

• Test for OE Project Monarch Health (University of Georgia) needs volunteers to test Monarchs that fly through Alabama for OE, a protozoan parasite that weakens caterpillars and cripples adult butterflies (see above). Some sampling has been done in Alabama, but more is needed to gain an accurate picture of our infection rate. Alabama data will be posted on this website. To participate, email Project Monarch Health(monarchhealth@gmail.com) to get a sampling kit; then net a Monarch, press a clear tape sticker to its abdomen, place the sticker on an index card, and mail the card to the lab when it is full. Stickers and index cards are provided in the kit. You will need to provide an insect net and thin disposable gloves. Small children’s insect nets are often available for a few dollars at stores like Walmart and Target but, if possible, we recommend using a larger, sturdier net such as those sold for less than $20 by RestCloud on Amazon.com.  Even better arer the professional nets sold at Moth and Beetle (https://mothandbeetle.com).

• Discover and Report Wintering Monarch Sites More information is needed to understand where and how Monarchs are spending the winter in Alabama. Report the Monarchs that you see from Dec 1--March 1 to Journey North. To participate, create a free account at journeynorth.org/reg. Then, learn how to report sightings at jouneynorth.org/monarchs. Finally, from December 1 through March 1, submit Monarch observations at journeynorth.org/sightings.

Please submit questions and comments to al.butterflyatlas@gmail.com