31 October 2012

Summary for Five Years of Omaha Bird Strikes

Since May 1st, 2008 there have been 1421 known window-strikes by birds in the Omaha area. On that first spring-day in downtown, five instances were discovered on the sidewalks of the area. Since then, strikes have been documented on 419 additional dates.

The majority of the details have been personally gathered, with twenty of these records from May-October 2012 as denoted by staff of the National Park Service, at their riverfront headquarters building.

There are 102 species that have been recorded. There are actual records for 101, plus another — American Woodcock — as denoted during a personal conversation with someone who personally knew of this bird hitting glass at a private area, not accessible for any survey attempts, the Conagra Campus at the riverfront.

During this period, strikes have been denoted on 181 different days of the year, from Julian Date 96 (April 5, 2012) to Julian Date 332 (November 27, 2008). Window-strikes may have occurred during other dates, but would have less likely been denoted due to weather conditions not suitable for what has primarily been a bicycle-based survey.

Window-strike Details

The following is a summary of details, which are especially pertinent, and poignant after so many mornings where dead or disabled birds were personally observed.

Number of Records for a Specific Species

Bird Species: Number of Instances

Lincoln's Sparrow: 155
Common Yellowthroat: 151
Purple Martin: 98
Common Grackle: 85
Nashville Warbler: 85
Clay-colored Sparrow: 47
Indigo Bunting: 42
Wilson's Warbler: 42
Tennessee Warbler: 41
White-throated Sparrow: 41
Mourning Dove: 32
Mourning Warbler: 30
Ovenbird: 28
Orange-crowned Warbler: 28
Dark-eyed Junco: 24

Gray Catbird: 24
Rose-breasted Grosbeak: 23
Grasshopper Sparrow: 21
Marsh Wren: 20
Northern Waterthrush: 20
House Wren: 20
Yellow Warbler: 17
Sora: 16
Brown Thrasher: 15
Swainson's Thrush: 15
Yellow-billed Cuckoo: 14
Baltimore Oriole: 14
Swamp Sparrow: 14
American Robin: 13
Ruby-throated Hummingbird: 12

A total for the species given does not equal the overall tally, because in some instances a specific identity could not be determined since, perhaps, the carcass was too mangled, the little bird flew away, or some other reason obvious during at the time during the years.

Greatest Tally at Particular Buildings

There are 89 different buildings where bird strikes are known to occur. Several have just a single record. The following have numerous and repeated instances.

¶ Qwest/CenturyLink Center Omaha: 440 known occurrences (ca. 31% of the overall number) where birds have hit the glass of the building exterior, primarily on the west side. Deterrent decals placed upon the upper portion of the west wall glass a couple of years have been ineffective, as more strikes occurred in 2012 than previously determined. Overall, there are 231 dates represented during the five years: 2008: 60 dates and 123 records; 2009: 60 dates with 104 records; 2010: 22, 37; 2011: 20, 34; 2012: 69 dates, with 143 records.
¶ 1200 Landmark Center: 112 records as follows starting in 2008: 19 dates, 28 instances; 2009: 27, 37; 2010: 16, 17; 2011: 6, 7; and, 2012: 20 dates, 23 instances.
¶ Holland Performing Arts Center: 99 known occurrences occurring in 2008: 22 dates, 27 instances; 2009: 18, 26; 2010: 16, 22; 2011: 9, 9; and, 2012: 9 dates, 15 instances. There is undoubtedly a greater extent of occurrence as building staff do their best to remove carcasses and drive away disabled birds, as personally noted during the autumn of 2012; their latest remodeling effort will increase the hazard as it is has transparent glass on the south side and north side, and there is a situation of glass walls and light in an interior courtyard from which birds have trouble escaping.
¶ Kiewit-Clarkson Skywalk, on the Nebraska Medical Center campus: 97; predominantly Purple Martins which strike the building walkways despite efforts of using banners to provide a visual banner. The largest number of strikes occurred in 2008 (38) and in 2010 (17) and 2011 (10), which represents a decline as coverage was consistent.
¶ Union Pacific Center: 89, with an obvious decline, primarily because of the removal of interior vegetation on the north side. The company also has placed informational signs in the atrium areas, urging staff to close blinds and turn off lights. The change is reflected in the numbers, thus 2008: 27, 36; 2009: 23, 28; 2010: 7, 8; 2011: 9, 9; and, 2012: 7, 8, mostly on the south side of the building.
¶ Central Park Plaza: 75 overall, thus 2008: 19 dates and 29 instances; 2009: 21, 21; 2010: 5, 6; 2011: 6, 7; and 2012: 9 dates, 12 instances. There have been no measures taken here to reduce the hazards associated mostly with the lower glass areas on the east side of the two towers.
¶ Zorinsky Federal Building: 53; a U.S. building where the building manager has been informed several times about the bird deaths
¶ First National Tower: 49, where there has been an ongoing occurrence of strikes, and where officials made numerous comments and have made no effort to reduce obvious building hazards.
¶ Omaha Public Power District Energy Plaza: 45, where strikes continue to occur despite pioneering attempts to reduce the hazard by placing screen material on the glass.
¶ Gottschalk Freedom Center: 44, thus, 2008: 19 dates, 22 instances; 2009: 3, 3; 2010: 2, 2; 2011: 5, 6; and, 2012: 7 dates, 11 instances. The expanse of glass where these strikes occur is on the west side. As the park-space to the west develops further, the tree-canopy is increasing, and there will likely be an increase in bird-strikes due to the reflective character of the wall. No measures have been taken to address the situation of the building, operated by the Omaha World-Herald company.
¶ Omaha-Douglas Civic Center: 38, with non visits in 2008, thus 2009: 12 dates, 14 instances; 2010: 7, 7; 2011: 3, 3; and, 2012: 12 dates, 4 instances. A majority of these are at the glass wall on the north side of the atrium. No efforts have been made to reduce the tally.
¶ Harper Center, Creighton University: 26, with no recent records, which was probably mostly due to the closure of blinds on the buildings south side.. The recent completion of the Rasmussen Sports and Fitness Center and the landscaping placed on the south side, has added a new hazard to the area, however.
¶ Law Building: 26; at a vacant building
¶ Curtis Park Service Building: 23 at the regional headquarters for the National Park Service. There are a couple of small decals on the exterior glass, but the 20 occurrences indicates an obvious danger exists here along the river.
¶ Woodmen Tower Skywalk: 21
¶ Redfield and Company Building: 16
¶ Omaha World-Herald Building: 14

Areas managed as a campus where strikes occur at different buildings include:

  • the Nebraska Medical Center campus, including buildings operated by the University of Nebraska Medical Center.
  • the University of Nebraska at Omaha city campus, including the UNO Criss Library - Tritsch Garden and UNO Health, Physical Education and Recreation Building; the new community center to be built soon also will have features known to cause bird strikes at other places. This structure will also "block" the only near-ground open-space from the tree-laden yards of the neighborhood on the north side of Dodge Street, and Elmwood Park to the south.
  • the Conagra Campus, based upon second-hand comments, and because of the proximity of large windows near the pond at Heartland of America Park and birds moving along the bank of the Missouri River.

Greatest Number of Instances on a Particular Date

The dates when the larger number of strikes occur are predominantly during the autumn, when birds raised during the breeding season are migrating, and experiencing new hazards in urban landscapes.

Date: Number of Instances

10/24/2009: 31
09/25/2008: 23
10/20/2009: 20
09/13/2008: 17
09/28/2008: 16
05/24/2012: 15
09/09/2012: 15

08/28/2009: 14
09/24/2009: 13
09/26/2008: 13
10/07/2010: 13
09/13/2009: 12
09/26/2010: 11
05/29/2008: 11

05/10/2008: 10
05/26/2008: 10
09/18/2012: 10
10/22/2012: 10

More details can be derived from the available window-strike records, especially temporal details for bird groups, extent of records at particular places, and calendar distribution of records at particular buildings.

There are also the general perspectives from the federal agency responsible for bird protection, efforts to reduce window-strikes and considerations regarding their efficacy, newly constructed buildings which are another threat to migratory birds, the disposition of bird carcasses, and perhaps, how building owners respond to their discovery that their structure is a bird hazard.

This summary has been prepared in particular to convey details to the U.S. Fish and Wildlife Service, Ecological Services Office, Grand Island, Nebraska which — based upon several phone conversations thus autumn — has seemingly agreed to initiate an education and outreach program for the Omaha area. Details are not known.

There were ten more strike occurrences on Thursday, November 1st, represented the American Tree Sparrow, Harris's Sparrow, Lincoln's Sparrow and Dark-eyed Junco. Seven of them were at the CenturyLink Center Omaha.