Ask MDC

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

Q: Do great blue herons migrate?

Yes. By the end of December, most of North America’s great blue herons have migrated south to the Gulf Coast, the Florida Panhandle, and the lower Mississippi River. However, even in the depths of winter, some of these partial migrants stay in Missouri, particularly in areas where ponds and reservoirs remain unfrozen.

These herons have been observed migrating alone, in groups of three to 12, and in flocks of up to 100 birds; however, scientists still have more to learn about this species’ migration patterns.

Once they begin to return in May, they gather in large nesting colonies near water and food. Each pair of great blue herons typically lays three to six eggs, which are incubated for nearly a month. The chicks hatch one at a time, with the first to hatch growing more quickly than the others. It’s a good idea to maintain a distance from breeding colonies, since chicks can suffer fatal accidents in their haste to escape.

More information about Missouri’s great blue herons is available online at short.mdc.mo.gov/4p9.

Q: What caused this pattern in a soft maple?

This phenomenon is called the compartmentalization of decay in trees, sometimes called “CODIT” by foresters.

Over 400 million years, trees have evolved into the tallest, oldest, and largest organisms on the planet. And yet, unlike animals, they lack the ability to move out of harm’s way or heal damaged vascular tissue. And so, instead of healing wounds, trees compartmentalize the decay by forming a series of four “walls” around the injured, infected wood.

When sapwood is injured, the tree initiates processes that isolate the wound from normal tissues. Cells near the site excrete substances that are water-resistant and microorganism-inhibiting. Cells that would normally conduct sap, resins, or oils become plugged above and below the damaged section. The cambium — a thin layer that gives rise to new cells — begins to form a new, protective wall that is both anatomical and chemical. Of the four walls, it’s the strongest and helps separate the wounded portion from the tree’s new growth.

It’s hard to say exactly what might have wounded this maple; knowing more about the tree’s history would help. However, physical injury or fire are both plausible explanations.

More information about this topic is available online at short.mdc.mo.gov/4pj.

Q: In an old lead mine at Lake of the Ozarks, I found this bat, which appeared to be “crystallized.” While other bats were living in the mine, this one was the only one with this appearance. What is occurring?

Tiny water droplets caused by condensation contributed to the crystalline appearance of this tri-colored bat (Perimyotis subflavus). When hanging in a cave or mine with high humidity and little air movement, a bat’s body can become so cool that water condenses on the surface of its fur and skin.

Tri-colored bats hibernate up to eight months per year, relying on fat stored during the fall to survive. Mating occurs in fall, intermittently throughout winter, and again in spring. Relatively small maternity colonies start forming in mid-April.

To avoid disturbance to endangered and imperiled bat species, only enter caves with landowner permission, with experienced individuals, and while following decontamination and safety protocols.

More information can be found at whitenosesyndrome.org.