Monarch butterflies are perhaps one of the most well known butterfly species thanks to the legendary monarch butterfly migration that takes place each year. These tiny insects can travel up to 3,000 miles annually in search of a warm and cozy place to call home for the winter. Their destination? Mexico! Here in Texas we are lucky enough to be in the middle of one of the monarch migration pathways, so each summer and fall we witness these beautiful butterflies all around town. But what happens when our flying friends get caught in an unexpected cold spell?
Generally, butterflies won’t fly if it is below 55 degrees, and if the temperature falls below 40, they lose their ability to crawl. There have been documented occasions where a rare snowfall has taken place in their winter roosting areas in Mexico, but most are able to survive this because they are sheltered by forest cover. Those that do not receive this shelter can survive in the snow for a while due to the natural insulation snow provides, but extremely low temperatures can be life threatening, especially if the butterflies are wet and ice crystals form on their wings. That being said, when the latest cold front hit Houston, everyone on Zoo grounds was on high alert looking for monarchs in need of help. Staff in the Children’s Zoo set up a butterfly tent in the Swap Shop as a refuge, and sure enough, reports of cold-stunned butterflies started coming in. So far, butterflies have been brought to the Swap Shop for shelter and warmth by members of the Horticulture and Children’s Zoo staff, as well as Zoo guests. When the butterflies were first brought to our team of caretakers, they weren’t moving, and one was even thought to be dead. Fortunately, after a little bit of time in the warmth, they began to warm up their bodies by shivering and fluttering their wings. The team will continue to care for these butterflies until warmer weather returns and it is safe for them to be released back into the wild.
For the past two years, Houston Zoo staff and volunteers have been taking part in field work here on Zoo grounds by tagging monarch butterflies. If you have visited recently, you may have seen small groups walking through the Zoo with nets, in search of butterflies. Tagging is an extremely useful tool, as it can provide information about how and where the animal travels. Because all the migrating monarchs are concentrated in just a few locations during the winter, they are especially vulnerable to harsh weather and to human activities that disrupt or destroy their habitat. This can reduce the number of monarchs that leave the overwintering sites in the spring, and a reduction in milkweed and nectar sources can cause a decline in the number of monarchs that make it to Mexico for the winter. By tagging the monarchs and tracking their movements, protection plans can be set up in key areas that will help to ensure their survival. 93 monarch butterflies have been tagged on zoo grounds since 2016 as part of a project run by Monarch Watch.
While we all do our best to stay warm this winter, don’t forget to keep an eye out for monarchs that may need your help! Each time you visit the zoo, a portion of your admission ticket goes towards saving wildlife, which makes it possible for us to help local species like the monarch butterfly! If you are on Zoo grounds and see a cold-stunned butterfly, notify a staff member and they will help you get it safely to the Swap Shop. You can help pollinators like the monarch butterfly in your own backyard by planting native plants. Not sure what to plant? On your next visit to the Houston Zoo stop by the Conservation Stage, located to the right as soon as you enter. The Conservation Stage is lined with native plants and signs letting you know what each plant is! Simply take a picture of the sign and bring it with you when you go to the nursery to buy your plants! For more information on how to raise and protect monarchs and other butterflies, click here.