This past month we have been spending a lot of time at the Curlew National Grasslands for a very special reason: Monarch butterflies.
The Curlew is a grassland managed by the Caribou-Targhee National Forest and is composed primarily of agriculture land that was retired decades ago and now serves as expansive, rich habitat for a whole slew of species. It is a very special place whose location in southeast Idaho gives it the unique ability to serve as part of the highway for western populations of monarch butterflies during their yearly migration to California. Monarchs flock to the Curlew to rest, mate, and start a new generation in the shade of its riparian areas that are chock full of showy milkweed (Asclepias speciosa).
Unfortunately, loss of habitat and food sources have caused monarch populations to plummet. The western population is really struggling and where thousands upon hundred thousands of monarchs used to pass through the western United States now only a few hundred or thousand are seen.But the Curlew hasn’t given up on Monarchs yet! It still welcomes them with the promise of shade, food, and a possible mate in the area. For that reason, monarchs are still flitting through the expansive grassland.
As interns on the Caribou-Targhee we had the privilege of partnering with state agencies and citizen scientists to document the monarchs passing through the Curlew this year. (Here I was, thinking I would never see or experience what it is like to see monarchs migrating when suddenly I am thrown right into the science behind tracking and monitoring them!) Monarch surveys occur all over the United States and are fueled by the research and work of people like Dr. David James and organizations like the Integrated Monarch Monitoring Program-thankfully, there are a lot of people that care about monarchs 😊
Preforming monarch surveys means gearing up with butterfly nets, data sheets, sunscreen…and lots of water…and then getting to work. And let me just say, catching a butterfly is not as easy as it seems…but when you do finally catch one you cannot help the smile that spreads over your face, it’s the best combination of science and feeling like a kid again. Gently reaching in and grasping the little migrant in the proper way and sliding them out of the net is a surprise in and of itself because suddenly the vibrant colors of their wings and sharp white polka dots on their black body are no longer muted by the mesh of the net or the haze in the air. And my goodness are they are exquisite. Some of them are more tattered and torn around the edges letting you know they have come to the Curlew to mate and continue the migration through their offspring while others are almost fluorescent in color and itching to travel.
The butterfly patiently grasps your fingers as you attach a small tag to the proper area of its wing (so that its flying ability isn’t hindered) and reluctantly allows you to open up its wings (with which you get another pleasant shock of wonder as their deep orange wings, rimmed and webbed with velvet black, completely open in front of you) and look for the presence or lack of a small black dot on each wing. If the monarch has these dots it is a male (other butterfly species’ males emit pheromones from these dots of specialized scales, but the jury is still out on what monarch males use them for) and if not, it is a female. After checking that you have written down all the necessary data you slowly detach your fingertips from their wings. At this point, it is a 50/50 chance whether the monarch will leap back into the sky immediately or stay on your finger for a bit, gently flapping its wings and making up its mind (all to your complete delight). Experiencing monarch butterflies in such a hands-on manner was amazing-something I never thought I could have done!
But we don’t just pay attention to the adults; monarch surveys also include searching for instars on the milkweed plants and tiny monarch eggs. This means recognizing monarch instar leaf grazing and peering over and under the soft milkweed leaves in search for the happy culprit. When an instar is found you can tell what stage it is in by the presence or lack of stripes and antennae. Data is recorded and the instar grazes on; you can almost see it growing in front of your eyes as it chops away leaf after leaf! Monarch eggs are a bit harder because spots of dried milkweed latex on the leaf can fool you repeatedly. But when you finally find an egg, you realize that they have an incredible design: small and rounded at the bottom with a slight Hershey’s kiss top and vertical lines traveling up across its entire surface. Perfect looking and so small you must confirm it using a hand lens! We also care a lot about monarch habitat and need to document the characteristics of the areas they frequent in order to better understand how we can remediate the loss in their numbers. This means walking transects and using vegetation frames to collect data on the landscape that the monarchs love. The healthy mix of nectar plants, milkweed, and shade trees on the Curlew is what the monarchs really seem to key into in southeast Idaho!
Thanks to interagency collaboration and the help of citizen scientists the presence of a special section of western monarch’s migration highway at the Curlew was confirmed again this year with notably high monarch counts for the entire western half of the Unites States. I was so happy to be a part of it 😊