Ask MDC

Got a question for Ask MDC? Send it to AskMDC@mdc.mo.gov or call 573-522-4115, ext. 3848.

Q: How can I keep snakes out of my purple martin birdhouse?

Your best bet may be to install a stove-pipe baffle. These predator guards are helpful in preventing pole-climbing predators — such as snakes, raccoons, or squirrels — from eating purple martins’ eggs and young. You can read more about predator guards and how to make one at short.mdc.mo.gov/4w5 and short.mdc.mo.gov/4wS.

Q: In the May/June 2021 edition of Xplor, a paragraph about fireflies noted, “ … biologists believe their flashing backsides have another purpose: The blinking may serve as a signal to hungry bats that the firefly is toxic and shouldn’t be eaten.” I was taught bats are blind and use sonar to navigate. Do they have some limited vision available to see a firefly?

Bats do indeed have sight! While hearing is their primary sensory system, they can see about as well as humans can, so how much they utilize vision can depend on the amount of moonlight on a given night. Some bats also can detect ultraviolet light that may be reflected off insects or flowers.

The saying “blind as a bat” is a bit of a misconception; bats are sensitive to their environment whether they are using sight or not.

Q: We have many cardinal pairs at our feeder, but this year we noticed a behavior not previously seen. The male was picking up seeds from the ground and putting them into the female’s mouth. What was happening here?

This is a courtship behavior between the male and female. Courtship feeding may be more than merely ceremonial or help with pair-bonding. Scientists think it provides the female with significant nutritional benefits at a time in her life when the number of eggs she’s able to produce, and the total weight of the clutch, is related to her health status. Courtship feeding is also a way to induce copulation and reduce aggression between the sexes. And, by keeping a female mate healthy, it’s a way for the male cardinal to increase his own reproductive success.

Q: Is this an eastern tiger swallowtail caterpillar? Aren’t they bright green, though?

Yes, it is an eastern tiger swallowtail caterpillar (Papilio glaucus). Like most other caterpillars, it has changed to a darker color because it is finished feeding and is seeking a location to pupate. Some scientists think caterpillars change color during this time to avoid predation. When these caterpillars are feeding on green leaves, bright green is better camouflage; when they are walking on tree limbs or the ground in search of a place to pupate, a duller earth-tone provides a higher degree of safety.