Reflections on Butterfly Tagging

Reflections on Butterfly tagging

MLT Land Trust Tagged Monarch

The Center for Biological Diversity states that 80 – 85 percent of monarchs have declined over the past twenty years. The IUCN estimates that the native populations of Monarch butterflies has shrunk by between 22 percent and 72 percent over the past decade, and the western population has declined by 99.9 percent between the 1989’s and 2021, putting these butterflies at the greatest risk of extinction. Yet the monarch has only been put on the endangered species list this year. Why such a discrepancy?

Meanwhile scientists (and now just about anyone including children) have been tagging monarchs for many years so that folks could find out more about migration.

Nowhere do I see mention about the possibly destructive relationship between tagging and monarch survival. The loss of milkweed, the continued destructive use of pesticides, weather changes etc are all attributed to the decline of this iconic butterfly.

One salient point is made by some scientists: While touching a butterfly’s wings may not kill it immediately, it could potentially speed up the fading of the colors on the butterfly’s wings, wiping out patterns that are used to protect the butterfly from predators.  Thus handling a butterfly could potentially result in a shorter life expectancy.

Do we really need studies to tell us that monarchs that are captured in nets and then tagged undergo trauma and stress that might interfere with the insect’s ability to make a perilous 2000 mile trip to the mountains of Mexico for the winter? Some studies are in and more are being done, but common sense tells me that stress weakens immune systems leaving the insect more vulnerable.

Just imagine for a moment that you are a butterfly. You are caught fluttering in fright in a net and then held firmly by the wings by a human who places a tag on your lower wing removing precious scales in the process (I have also read that in some cases the scales have been scraped away before attaching the tags). This tag is supposed to be close enough to the butterfly’s center of gravity so that it won’t upset the insect’s balance. But do we know this for fact? Any weight that is not at the butterfly’s center is going to create some imbalance. Again, common sense.

Yesterday I had a conversation with a couple of scientist friends of mine who confirmed my hypothesis – namely that tagging obviously creates an imbalance. 

 MonarchWatch, an organization based at the University of Kansas has tagged approximately two million monarchs over the past 30 years. Out of those two million 19,000 monarchs have been documented to have made a ‘successful’ flight to Mexico meaning that when the tagged monarch was found the monarch was DEAD and would not be returning north in the spring. Death means that the butterfly’s natural cycle was interrupted. We don’t know what happened to the others but new research is indicating that there is an increasing mortality occurring during monarch fall migration. Are we going to attribute those missing in action to the use of pesticides etc without including tagging as one of the reasons these monarchs haven’t been seen again?

Why are we tagging monarchs in the first place? Historically scientists and now citizen scientists are “trying to help the monarchs” and learn more by documenting migration of the species. Obviously the intent is laudable but no one mentions how the monarch might be actually be faring.

Is this practice helping the monarchs survive? Is it beneficial to these insects in any way, or is it occurring because humans routinely sacrifice animals to acquire new information for themselves? Science prides itself on being ‘value free’ meaning that emotion and feeling are not part of the process, so who is left to care about how a butterfly might feel? Or ultimately whether an individual lives or dies.

I leave it to the reader to answer this very important question. 

Please see: for an informed discussion on this topic.

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