Ask the Expert - Questions and Answers

"Ask the Expert" Questions & Answers

Here are the questions that have previously been submitted and their answers from our experts. The most recent questions are listed first. You can also view the Questions by Category. Don't see the information you're looking for? Ask your own question.

1 2 3 4 5 6 7 8 9 10 ...

I've read that the monarch butterfly is not an endangered species, but that the monarch migration is an "endangered phenomenon." My question is if this phenomenon does become extinct, what will happen to the migrating Eastern population? Will it simply become a resident population in Mexico? Will it cease to have a "Methuselah generation"?

You are correct, the Eastern North American monarch migration is an endangered phenomenon, but this is not the only population of monarchs, and thus the monarch species is not endangered. Monarchs exist in other locations around the world. These populations do not undergo a migration as phenomenal as the Eastern North American population, if at all. It is not easy to predict how the E. North American population will adapt to habitat loss throughout the breeding range, and overwintering site degradation in Mexico. If the overwintering sites in Mexico become unsuitable for monarchs, they will be forced to either adapt to new overwintering locations, or they may not survive. With a changing climate, the distribution and abundance of milkweed throughout the breeding range may change, which in turn would shift the distribution of the monarchs that use those milkweed plants. Questions about these "What if?"s are yet to be answered, so it is unclear exactly what is in store for the future of the North American monarch migration.

The monarch butterfly uses sequestered toxin and aposematism to thwart predators. Research shows that butterflies or larvae with higher toxin concentrations are less likely to be predated. Aposematism is an all or none proposition, coloration doesn't change with toxin concentrations. How do the predators sense that one monarch has more toxin as compared to another?

Hello and thanks for the interesting question!

Of the studies that I am aware of, predators (usually birds) have been initially exposed to monarchs of either high or low toxicity. After experience with these prey items, the predators tend to learn that monarchs are good (low toxicity) or bad to eat (high toxicity) and adjust their future behavior accordingly. Predators that have consumed distasteful butterflies will likely avoid similar looking butterflies in the future, while predators that have consumed palatable butterflies will continue to recognize similar looking butterflies as prey, at least until they meet a distasteful one. The original studies on this were done using blue jays, but since then, similar studies have been done using other birds, as well as spiders and mantids.

Because most butterflies in one geographic area are liekly from the same milkweed species and of similar toxicity, this same dynamic could play out in nature. Areas of low toxicity milkweed could have higher rates of monarch predation, and vice versa in regions with more toxic milkweeds.

I'm not aware of any predators that distinguish between prey items on a case-by-case basis, but if you have a specific study in mind, I would love to hear about it!

On a related note, I am interested in how parasitic wasps and flies might choose between monarch hosts based on their toxicity. Many of these insects are able to sense and taste hosts before placing their eggs on that host, unlike predators that often consume butterflies in one big bite.

Is it possible to tour monarch overwintering colonies in the oyamel fir forests of Mexico?

Yes! There are between 5-14 overwintering colonies that occupy the oyamel firs in Mexico each winter. Some of the colonies are not open to the public, but there are a few that tourists can visit. Butterfly reserves at El Rosario and Sierra Chincua are just a few that are open to public visitors. The monarchs usually reach the overwintering colonies beginning in early November and start to disburse in March.

What makes Monarchs superior to other butterflies?

Although it might be said that all butterflies have intrinsic value, monarchs are unique in many ways. Monarchs are not an endangered species, though their annual migration is considered a threatened phenomenon. The monarch is an important species in conservation because it is a showy and charismatic species, is culturally significant, geographically widespread, and has a biology friendly to educational purposes. These characteristics make the monarch a good representative for progressing public awareness about pollution, habitat destruction, and other environmental threats.

I live in Pennsylvania, have recently collected a few milkweed seed pods and collected the seeds and planted indoors in a greenhouse. 2 weeks later... nothing! Since the seedpods I collected have been outside on stems all winter wouldn't that be cold stratification? Should I collect some more seeds and try again or should I try some cutting from established plants in the spring? Any insight would be appreciated

Have patience - sometimes it takes quite awhile for seeds to break dormancy, which will delay the emergent growth. While this is likely your case, you can also try collecting seeds again and bring them indoors to stratify in your refrigerator. Cold stratifying in your refrigerator allows for a more controlled environment, and can easily be done with a moist substrate (peat produces the best results, though paper towel, clay, or sand are other options). Store the seeds in a dark container of moistened substrate at 5 degrees Celsius (41 degrees Fahrenheit) for 1 to 3 months.

1 2 3 4 5 6 7 8 9 10 ...