On pelicans, pests and leaves: Answers to some recently asked questions
From birds to oak trees and beetles, anything goes in the FAQ department here at the nature center.
Finding answers to questions is one of the most fun parts of being a naturalist. Here are some of the questions recently asked.
Planning for pelicans: "When will the pelicans be here?" ask many folks, eagerly awaiting the arrival of these awesome birds.
American white pelicans are the biggest draw to our forest preserves in Kane County, but they're only here once a year. They have appeared in the spring for several years at Nelson Lake Marsh in the Dick Young Forest Preserve in Batavia. People come from miles around to admire the huge white birds. A caller from the city of Chicago anxiously asked when he could come out to see them.
Before you pack your binoculars and hop in the car, hold on. The truth is, we don't have their itinerary. We know generally of their flight path, but the travel plans are up to them.
American white pelicans spend the winter along the Gulf Coast and in southern California and Mexico. They travel north to breed in Manitoba, Canada and the northern plains states, as well as inland in northern California, Nevada and southern Oregon.
"Our" pelicans - the ones we see in Kane County during migration - are generally the Gulf Coast vacationers. Their route takes them northwest through Illinois in the spring as they head to the northern plains. The white pelicans that winter in southern California and Mexico generally head to the California-Nevada-Oregon breeding grounds.
"Years ago there were only a few," said Bob Andrini, president of Kane County Audubon. "Then their numbers increased."
Andrini and other birders have seen flocks of up to 300 have been seen during recent spring migrations. They are spectacular birds in flight, and striking in appearance on the marsh.
Why do they stop here? Habitat. With years of habitat restoration at preserves such as the Dick Young Forest Preserve, the wetlands have become more and more appealing to migrating birds such as the white pelicans. That is, until the drought of 2012 dried up the marsh, and the eternal winter of 2014 kept everything frozen at critical migration time.
Flocks of American White Pelicans were spotted in Lake County last week, but as of this writing, none have been seen in Kane County. They may pass us by.
Leaves that don't fall off: What's up with the trees that kept their leaves all winter? People often wonder why some trees keep their leaves and others don't. This is a common question that has one of those, "It's complicated" answers.
Here's the scoop: Each fall, a separation layer develops between the leaf stalk and the branch of deciduous trees. Sometimes, the separation layer doesn't form completely. The leaves hang on throughout the coldest of winters, but they will be pushed off when the buds of new leaves burst in spring. This is more common in some types of trees, such as oaks, and more common in juvenile trees.
The term for this phenomenon is marcescence. It's not really known why some trees are marcescent and others are not. If anything, holding on to leaves in winter seems to be a disadvantage, because heavy snow can collect on the leaves and cause limbs to break.
I haven't found any material indicating that there's an evolutionary advantage to marcescence. Artistically, it makes for a beautiful sight. There's nothing like a gnarled oak tree with brown leaves rattling in a winter blizzard. But we've had enough of winter blizzards, and it's time for those new leaves to appear.
What about the Emerald Ash Borer? Another question that we hear is whether the cold winter has killed the destructive Emerald Ash Borer beetle.
This insect, also known as EAB, has decimated all species of ash trees in numerous states, and we have been hard hit in Kane County. Rumors have it that the well-below freezing temperatures have reduced the number of EAB larvae. Wishful thinking. The ability to withstand cold is called cold hardiness. Research is underway to measure the cold hardiness of the ash borer, but like many insects, the EAB has a natural antifreeze that protects it throughout the winter.
Another survival strategy is staying well protected under the bark of trees. According to the Emerald Ash Borer website, the cold may not make a significant dent in the ash borer population. The site's links to experts in Michigan and Indiana show that entomologists are doubtful that the larvae have been killed by our cold winter. Bummer.
Songs of spring: Last but not least, we are all asking, "Where is spring?" The cardinal outside my office window, singing in the sleet, assures me that it's coming.
• Valerie Blaine is a naturalist for the Forest Preserve District of Kane County. You may reach her at blainevalerie@kaneforest.com.