1. Project Description

Evaluating the drivers of bird-window collisions in North America / EREN Bird-window Collisions Project
Stephen B. Hager, Department of Biology, Augustana College, Rock Island, Illinois stevehager@augustana.edu, 309.794.3439
Bradley J. Cosentino, Department of Biology, Hobart and William Smith Colleges, Geneva, New York (cosentino@hws.edu)

Birds that reside in urban settings face numerous human-related threats to survival, including mortality from bird-window collisions (BWCs) (Klem 1989, Machtans et al. 2013, Loss et al. 2014). Recent work has demonstrated that the primary drivers of BWCs are the amount of windows in a building and proportion of development (Fig. 1; Hager et al. 2013). For example, BWCs were highest at commercial buildings in green space (50+ fatalities) and non-existent at small houses in highly developed areas. These results suggest that patchily distributed environmental resources and levels of window area in buildings create spatial variation in BWCs within and among urban areas.

Figure 1. Factors driving bird-window collisions: (A) total window area in each building and (B) development (% impervious surfaces).
Land use legacies and the nature of urban growth appear to affect variation in the numbers of individuals and species impacted by window collisions (Bayne et al. 2012, Machtans et al. 2013, Loss et al. 2014). However, the factors driving this variation within and among landscapes remain unexplored. Moreover, we currently have a biased understanding of the spatial aspects of BWCs since the bulk of previous research has been confined to large commercial and high-rise buildings. At a broader scale, study sites have generally been located in areas important for bird migration, such as along major migratory pathways and at urban sites at the edges of large bodies of water where staging areas (migration stopover locations) concentrate migrants. Indeed, the cities in which these studies have been conducted include not just skyscrapers, but rather locally unique and diverse configurations of urban development.

We are testing the hypothesis that the magnitude of BWCs within and among urban areas reflects landscape structure and functional connectivity. Collaboration among numerous sites in North America will allow us to examine the factors believed to influence window collisions, such as structural features of buildings and land use at local and landscape scales. This information is crucial for predicting local and regional mortality, which would focus future conservation efforts aimed at reducing collision-related impacts.

Selecting Study Buildings
In 2014, each site (N = 40 sites; click HERE for map) was required to select a minimum of six study buildings that were (a) separated by at least 100 m (wall-to-wall distance) from each other, and (b) stratified by both building size (as a proxy for window area) and surrounding green space (see table below as an example).

Measuring Structural and Environmental Variables
Collaborators were required to measure the following variables for each of their study buildings: (1) window area and (2) number of stories or floors above ground level, and (3) and floor space (which may be obtained from campus facilities or tax records). Local and regional development is being measured in a GIS by Steve Hager.

Fall Carcass Surveys
Each site completed one carcass survey each day for 21 consecutive days was completed at each study building between 15 September and 31 October 2014. We chose the fall season because the incidence of mortality is higher in the fall compared to other seasons (e.g., Klem 1989), and, thus, lends itself well to evaluating spatial variation in mortality.

Carcass surveys were completed in the afternoon hours since collision mortality predominantly occurs between sunrise and early afternoon hours, and scavengers are most likely to remove a carcass between sunset and sunrise (Klem 1989, Hager et al. 2012, Hager and Craig 2014). This sampling protocol minimizes bias that may result from imperfect detection of bird carcasses (Hager et al. 2012, 2013, Hager and Cosentino 2014).

Collaborator Training
All collaborators were provided with detailed protocols that explain how to select study buildings, digitize study building polygons, measure window area, and conduct carcass surveys. Thus, protocols were standardized enabling data to be comparable among sites.

**NOTE: Only basic and inexpensive supplies (e.g., ziplock sandwich bags for bird carcasses) and equipment (e.g., tape measure) were needed.

Authorship Guidelines (also found below as stand alone Word document for download)
We are following the authorship guidelines set forth by the Ecological Research as Education Network (EREN).
(1) Collaborators will be considered contributing authors on all publications and presentations that result from this work. Specifically, Collaborators:
  • Contribute data to the project by a specified deadline.
  • Review all drafts of presentation abstracts and manuscripts.
  • Remain in regular communication with the project PI's throughout the project.
Order of authorship will be alphabetized by last name after the names of the project PI's. Students will be considered for authorship if they meet the guidelines for a Collaborator and if their contribution was part of an independent project (rather than a lab exercise, for example).

(2) General Participants will be listed in acknowledgments section in all publications and presentations that result from this work if they contribute data according to the project’s protocols and guidelines and submit data in time for analysis by the project PI's.

Models for student involvement
Undergraduate and graduate students participated in a variety of venues: (1) a class on bird-window collisions, (2) an independent study, (3) a research experience/internship, or (4) a course module in an existing class, e.g., Ecology, Ornithology, Conservation Biology, etc. We provided education materials for a structured and collaborative investigation of BWCs using a case study and journal club workshop. In class work is then augmented by field data collection by students for further analysis and interpretation.

We developed education materials for academics that wish to run this project within the framework of a formal class (e.g., Introduction to Biology, General Ecology, Ornithology, Conservation Biology, etc.) and as part of internships/independent research experiences.

Status of the project as of Fall 2014
Results were published in 2017 in a paper “Continent-wide analysis of how urbanization affects bird-window collision mortality in North America” (Biological Conservation). A summary of this paper may be found HERE.

Literature Cited

Bayne, E. M., C. A. Scobie, and M. Rawson-Clark. 2012. Factors influencing the annual risk of bird–window collisions at residential structures in Alberta, Canada. Wildlife Research 39: 583–592.

Hager SB, Cosentino BJ. (2014) Surveying for bird carcasses resulting from window collisions: a standardized protocol. PeerJ PrePrints 2:e406v1 http://dx.doi.org/10.7287/peerj.preprints.406v1.

Hager SB, Craig ME. (2014) Bird-window collisions in the summer breeding season. PeerJ 2:e460 http://dx.doi.org/10.7717/peerj.460.

Hager S.B., Cosentino B.J., McKay K.J. 2012. Scavenging affects persistence of avian carcasses resulting from window collisions in an urban landscape. J Field Ornith 83: 203–211.

Hager, S.B., B.J. Cosentino, et al. 2013. Window area and development drive spatial variation in bird-window collisions in an urban landscape. PLoS ONE 8(1): e53371. doi:10.1371/journal.pone.0053371.

Klem Jr., D. 1989. Bird-window collisions. Wilson Bulletin. 101:606–620.

Loss S.R., Will T., Loss S.S., and Marra P.P. 2014. Bird–building collisions in the United States: Estimates of annual mortality and species vulnerability. Ornithological Applications 116: 8-23.

Machtans, C. S., C. H. R. Wedeles, and E. M. Bayne. 2013. A first estimate for Canada of the number of birds killed by colliding with buildings. Avian Conservation and Ecology 8(2):6.

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