Naturalist’s Notebook

AVIAN WINDOW-COLLISION MORTALITY

An interview with

Tim O‘Connell, Wildlife Ecologist and OSU Associate Professor, Department of Natural Resource Ecology & Management

AG HALL— A dead hawk was found outside on a ledge right below our window mid-October. Dr. Tim O‘Connell, Associate Professor in the Department of Resource Ecology and Management identified the bird as a Sharp-shinned Hawk, from its bluish-gray wings and white belly covering its 13-inch frame. Its cause of death was deter-mined to be an in-flight window collision. Wanting to keep the hawk for his research, O‘Connell introduced us to some fascinating information about the growing problem concerning bird mortality rates. He noted that windows are a newly developed source of mortality for birds. “Everyone, whether into birds or not, can relate to the experience of find-ing a dead bird by a window”, O‘Connell said in a Q&A performed after the discovery, via email. As someone who is currently observing the correlation between bird migration and in-flight collisions on a daily basis, O‘Connell has collected various types of bird casualties on OSU‘s campus. He became interested in the issue 15 years ago during his residence in Richmond, Virginia. While jogging, he noticed several dead birds in the vicinity of various

“Everyone, whether into birds or not, can relate to the experience of finding a dead bird by a window.”

Buildings shielded with mirrored-glass. O‘Connell took notice of two things. One, the species were migrants, which probably died while passing through the area. Two, he thought the birds would be valuable additions to the collections at Virginia Commonwealth University where he knew its museum‘s bird curator. It was then that O‘Connell decided to find some way of quantifying the bird mortalities. So, he spent a year searching for birds around the same location, and keeping records of all his findings. He has been keeping track of relevant information ever since, and has developed his own methods that has led to his current conclusions about avian window-collision mortalities. The following information will contain summaries further looking into this topic, mostly incorporating O‘Connell‘s input about his own studies concern-ing this newfound phenomenon.

How Big of a Problem is This? Biologist Daniel Klem from Muhlenberg College in Pennsylvania was one of the first people to conduct experiments that explored the topic of birds striking windows. O‘Connell often uses Dr. Klem‘s findings to illustrate the severity of the issue. According to a fact sheet on Muhlenberg College‘s Acopian Center for Ornithology Web site, an estimate for the annual window-collision mortality in the United states ranges from 97 million to 975 million. O‘Connell shares that there are about 20 billion birds total in North America each autumn when annual populations peak. ―If the number killed by windows actually approaches a billion birds, then this one source of mortality is far greater than the number killed by cats, hunters, auto collisions, and pollution, and other factors,‖ he said. About 75% of bird-window collisions end up fatal for birds, Klem estimated. Even if a bird is merely stunned from the collision and attempting to recuperate, they could become an easy prey for predators, such as cats.

Examining the Problem O‘Connell‘s search for birds mostly revolves around the Noble Research Center roughly every morning. He tries to find birds that have died while migrating the night before. Getting to NRC as early as he can reduces the chances for any predator, or he adds, “some other well-meaning ornithologist on campus”, to remove the bird before O‘Connell ever gets the chance to record it. O‘Connell guesses he records about 90% of the total mortality at the building, despite the fact that there are some animals that do end up scavenging for the dead birds, such as cats, raccoons, opossums, skunks, or foxes. ―But the rate seems to be low, he said. After a bird has been collected, it is placed in a freezer with a card indicating the date and location the bird was found, as well as the bird‘s species, age, sex, and manner of death. O‘Connell also lists the fat scores of the birds. The fat score is an estimate of the bird‘s health and readiness for migration at the time of its death. Although window collision mortality is a minor component of O‘Connell‘s research program, he frequently reviews studies and proposals from other people doing similar work.

The Interest in Avian Window-Collision Mortalities

O‘Connell suspects that some species are more susceptible to this kind of mortality than others, reflecting the amount of urban development that has occurred along certain migratory routes. Although windows might be one of the primary dangers for migrating birds, it is difficult to determine what sort of broad impact this mortality might have on any one species‘ population. To estimate the relative influence of window-collision mortal-ity for a species would require reliable estimates of the total population of the species, a coordinated effort among multiple sites to estimate all sources of mortality, and some complex statistical modeling. For now, O’Connell is just trying to test the feasibility of regular monitoring to see if it would make a good research project for his undergraduate students. Discussing window-collision mortality on bird-related listservs is one of O‘Connell‘s ways of spreading the word about conservation issues that affect wild birds. Another way he expresses his findings is through his new blog, started last August, titled, “Avian Window Kills.” The blog serves as a regular online record of the window collisions that have occurred at the NRC. “Blogs are an exceedingly simple and uncluttered place online where people can go to obtain information on this phenomenon, and track the regular progress‘ of my findings”, O‘Connell said.

Conclusion One compelling fact that prompts O‘Connell to say that this issue is a “big deal”: birds have always had to deal with predators, rough weather, and food shortages during migration. However, it has barely been 200 years that they have had to deal with windows during their trek. “There probably hasn‘t been time for birds to evolve in their behavior for complete avoidance of human structures while on migration—especially considering they‘ve had eons of evolution shaping their behavior to follow those exact routes where we‘ve put up a bunch of buildings”, O‘Connell said. His original plan was to survey the NRC for window-killed birds from August to October, but an increase in casual-ties has him extending his searches, perhaps for a full year. A possible alternative based off of his findings recorded on his blog would be building a database to share his analyses. He said while it is important to analyze these data for publication in scientific literature, information in journal articles is not nearly as accessible or timely as in a free, daily blog.

To visit Dr. O’Connell’s blog, go to http://birdsmack.wordpress.com

FALL BIRDING

Fall is the time to clean and stock feeders and to stock up on birdseed. Here’s what they’ll need.

At the Feeder

  • Repair any feeders that need a makeover. You may need to pound in a loose nail or replace a cracked bottom piece.
  • Put out several suet feeders so all your resident birds get a turn. A single woodpecker can monopolize a suet feeder for most of the day.
  • Stock a very low tray feeder (1 foot or less above the ground) with cracked corn for mourning doves, who gather in flocks to feed in fall.
  • Keep the hummingbird and other nectar feeders up as long as you dare; until freezing temperatures threaten; more that one late migrant has been saved by a forgotten feeder.
  • Keep the birdbath brimming. Fresh water is vital year-round.
  • In the Garden There are plenty of ways to provide bird treats in your garden in the fall. Try some of these ideas.
  • Keep an eye on any berries or fruits in your yard. They’re prime foods for birds that may alight during migration. The Virginia creeper that sprawls through my garden as a groundcover offers its midnight blue berries in early fall, right when vireos and orioles are passing through. The vines of fox grapes winding among the treetops attract later migrants like rose-breasted grosbeaks and tanagers.
  • Listen for the quiet twitters and sharp chip! notes that betray the presence of song sparrows, white-throats, and other hard-to-see native sparrows around your yard. In the fall, a bounty of ripening seeds on garden plants, grasses, and weeds brings flocks of these LBBs (that’s “little brown bird” in birder talk) to backyards. They may stop at abundant seed patches for a morning or a whole week, but they’re small, quick moving, and wary of people, so you’ll hear them more often than you?ll see them.
  • Check garden centers and nurseries for viburnums, bayberries, and other shrubs that are already full of berries. Cart them home carefully so as not to dislodge the fruit, pop them into the garden, and the birds will reap the benefits immediately. One September I brought home three deciduous hollies; while I was planting the first one, cedar waxwings descended on the shrubs that were still in the pickup truck.
  • If you love a bargain, check the end-of-season sales at nurseries and garden centers. Trees and shrubs—usually the biggest investment you’ll make when creating a bird-friendly yard—are often available at half price. Although the selection may not be as big as it is during the spring, the savings are hard to beat!

    • Contributed by Donna Mackiewicz

If you would like to post a picture of an event of project please email them to Kristy at kristy_wicker@yahoo.com.