Migration

The Booth School's Harper Center viewed from the southwest; my office is among those atop
the large horizontal limestone elements in the foreground, with the atrium tower rising behind.

The interior of the atrium viewed from the third floor mezzanine.

A casualty-to-be-collected on the mezzanine roof viewed from the inside.

It’s bird migration season again, this time from northern summer nesting regions southward to warmer wintering grounds with good food supplies. The glass tower of the otherwise brilliantly designed Harper Center, Hyde Park home and global headquarters of the University of Chicago’s Booth School of Business, has been from the beginning a wall of treachery to migrating and resident bird life. The floor on which I work has a mezzanine lidded with a glass ceiling collaring the atrium’s tall tower. This is where the birds, flying full speed into what to all appearances is air and sky, smack down when they bounce off the glass. Some are merely stunned, and squat on top of the nearly horizontal glass, trembling, panting, and blinking until they catch their breath and fly away. But most hit with fatal force; from below, passersby see their colorful, stiff bodies, impossibly skinny legs in the air. Some, like the pair of monk parakeets that died there last week, are big and impossible to miss; at a glance, the hummingbirds, exquisitely tiny, could be beetles.

The Booth School has been doing whatever is reasonably possible to remediate the carnage. The window-walls have retractable blinds that are lowered to cut reflections in the day and the illusion of transparency when the interior is lit at night, thus much better creating the look of a solid surface. When the blinds are down, the collision rate drops. But there are still a few casualties, spring, fall, and in between.

Mary Hennen with a handful of
frozen birds at the Harper Center's freezer.

To make the best of the situation, the bodies are collected, bagged, dated, and frozen for study by the Field Museum of Natural History, a scientifically very active place behind the exhibits. My friend, Bird Collections Assistant Mary Hennen, retrieved a several months-worth of birds a couple of weeks ago. Here’s what the Harper Center tower sampled:

Tennessee Warbler (3)
American Redstart ( 2)
Magnolia Warbler (2)
Ruby-throated Hummingbird (2)
Willow/Alder Flycatcher (1)
Chimney Swift (1)
House Sparrow (1)
Starling (1)
Indigo Bunting (1)

The Harper Center is by no means the only structure in Chicago that provides birds for study. The problem is severe enough in our forest of skyscrapers that the City itself has provided an explanatory Web site with suggestions for remediation, and the well-organized volunteer Chicago Bird Collision Monitors (CBCM) valiantly aim to increase the survival chances of the injured.

The Field Museum uses these specimens in several ways, including to learn what species and which sexes are traveling through the Chicago area at what times; how weather affects migration and the number of “kills” (certain wind directions make some storms significantly more deadly than others), and body fat and condition at different time-points throughout the years.

One of the great surprises for me has been the vast variety of birds we have around us unnoticed. In the city we all know there are robins, sparrows, and, in the Colorful Department, cardinals. I would bet most people never appreciated the animated indigo buntings and bright yellow-and-black magnolia warblers when they were in the air and trees around them.

A magnolia warbler