Ask MDC

Q: We have noticed several of these being built in the overflow from a lake. Can you tell me what type of creature builds these?

These are crayfish chimneys. Although aquatic critters, some crayfish species can be found far from surface waters. These burrowing species dig down to the water table, sometimes up to 20 feet! So, you'll sometimes find them in unexpected places, such as prairies. A tell-tale sign of crayfish nearby are the "chimneys" they create from excavated soil. Find more information about this phenomenon .

Q: If I catch crayfish in a local lake infested with zebra mussels and use them for bait in another local lake, will I still be transferring zebra mussels? Can the crayfish themselves carry zebra mussels?

Regrettably, yes, crayfish can carry adult zebra mussels. These invasive, nonnative mussels have "byssal threads", or threadlike structures made of protein, which adults use to attach to hard surfaces. Even if a crayfish looks "clean", some very small mussels may still be attached. Numerous instances of crayfish with zebra mussels attached have been reported. So, if a zebra mussel has already attached to a crayfish you are using as bait, the chance exists it could be transferred to the new lake or pond.

Because of this risk and others, it's always a great idea to dump the complete contents of a bait bucket several hundred feet away from any lake, pond, stream, or other body of water.

Q: Two cardinals with patchy, sparse feathers are exhibiting strange behavior at my feeder. With tail feathers and wings outspread, they pose crookedly with their beaks held open. They take a seed now and then, but mostly perch on the feeder's edge. What's going on?

This behavior is typical when birds are hot and working to thermoregulate. As they open their mouths, they are panting in a way. Scientists call this "gular fluttering" because they are fluttering their upper throat muscles to promote heat loss. Birds can't perspire, so to cool off they attempt to circulate hot air away from their bodies instead. Lighter-colored birds may open their wings and spread their tail feathers to reflect light and heat away. All birds may do the same to take advantage of a cooling breeze. When they laze around at your feeder or in the shade, they're trying to stay cool by not expending much energy.

As for these cardinals' bedraggled appearance, this happens to many cardinals this time of year as they molt their feathers. Some cardinals molt many of their head feathers at once, making them appear bald.

You can help birds keep cool by providing a shallow basin of water with a few rocks to serve as perches, perfect for a cooling oasis to splash and drink. Keep an eye on water levels and clean out your bird bath daily.

Find more information on how birds stay cool.