Bird Feeders and Bird-Window Collisions

I write multiple blog posts each week for various websites and just last week wrote a paragraph in my thesis on the importance of communicating your science BUT amongst all that, I have failed to communicate my own science.

A few months ago I wrapped up my experiment looking at bird feeders and their effects on bird-window collisions. The data is now analyzed and the results all written up. Here’s what we learned:

In recent years many people have turned to bird feeding as a simple way to interact with nature. More and more people are living in cities than ever before and here interactions with wildlife are limited. Feeding wild birds has created this opportunity.This increase in bird feeders has created a new problem: collisions with buildings. The general public enjoys feeding the birds in their yard but they want to know how to do so safely.

This led to the development of the Birds and Windows Project: Bird Feeder Experiment. The project relied entirely on citizen science and the dedication of the 43 homeowners that were recruited within Edmonton, Alberta and the surrounding area.

The design of this experiment was quite simple. A bird feeder was present at 1 m, 5 m or absent from a study window for one month and then removed or added for the second month. The study was conducted over an entire year and the homeowner searched the study window for evidence of a bird-window collision every day of each trial. A total of 284 trials were completed at 55 windows.

Bird Feeders 1

Throughout the study there were 145 bird-window collisions. There were 51 collisions when there was no bird feeder present and this increased to 94 when a feeder was added in front of the window. The mean number of collisions was 0.64 per trial when the feeder was 1 m from the window and 0.72 when the feeder was 5 m from the window.

Comparing each window in its back-to-back trials (feeder vs. no feeder), we found 11 windows had a greater number of collisions when there was no feeder present while 16 windows had more collisions when there was a bird feeder present. 26 windows did not report any collisions at all, but the top 5 windows reported 24, 19, 15, 11 and 9 collisions while participating in the project.

Surprisingly, there was a lot of variation in the number of collisions when looking at the season the trial was conducted in. There was a mean of 0.11 collisions in the winter and this increased to 0.79 during spring migration, 0.54 in the summer breeding months, and 1.08 through fall migration.

Bird Feeders 3This study does support the results of previous studies. The highest mean number of collisions was seen when the bird feeder was the greatest distance from the window. However, there was a lot of variation between houses. This shows that the effect of a bird feeder is largely dependent on the individual home and window being evaluated.

Seasonality was seen to cause a lot of the observed variation in window collision rates. This wasn’t entirely surprising as more than 80% of the birds in Alberta are migratory. They’re just simply not as many birds present in the winter months to collide with windows.

Our results suggest that homeowners can reduce some window collision risk by altering feeder placement. However, this will likely not reduce collisions to zero, particularly at houses where collisions are common. Feeders are only one of many factors, including vegetation and house characteristics that influence whether a residence is likely to have a large number of collisions.

In conducting this study a number of participants provided updates on the activity at their bird feeder and at the end of the project a handful kept their feeder. Homeowners enjoy having birds in their yards and being able to feed them. Feeding wild birds creates an important link between the general public and nature and improving this relationship will continue to promote biodiversity and conservation. Finding successful ways for them to do so could be beneficial to both birds and the millions who feed them.

Bird Feeders 2

Post by Justine Kummer

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.

Klem, D., D. C. Keck, K. L. Marty, A. J. M. Ball, E. E. Niciu, and C. T. Platt. 2004. Effects of window angling, feeder placement, and scavengers on avian mortality at plate glass. Wilson Bulletin 116: 69-73.

Kummer, J. and Bayne, E. 2015. Bird feeders and their effect on bird-window collisions at residential houses. (submitted to Avian Conservation and Ecology)

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 building windows. Avian Conservation and Ecology 8:90-104.



Scavenger Removal Experiment Catches a Furry Friend

This fall the University of Alberta Birds and Windows Project launched a new Scavenger Removal Experiment at houses in the Edmonton area. This study was designed to determine the number of bird window collisions being missed by homeowners because bird carcasses are being removed by scavengers before they can be found.

As part of her undergraduate thesis, Colina Collins has been heading this project with the help of myself, Justine Kummer, and undergraduate student Elita Grinde.

In participating in this study, each house is being equipped with a small webcam and raspberry pi computer that has been programmed for motion capture photography. A bird carcass is then placed in front of the window of choice and in direct view of the camera. The Royal Alberta Museum has graciously donated a number of bird carcasses to this project. After a week we return to each home and analyze the photos.

We were very excited to find a squirrel in our pictures one afternoon. This little fellow found himself a delicious afternoon snack on November 7th.

22-20141107134742-01If you are interested in participating in the Scavenger Removal Experiment please contact us at


Wild Weather

Photo: Janet Ng.

Photo: Janet Ng.

Spring snow storms, tornado warnings, hail storms, and thunder storms are all part of field work. While we can take cover in our houses and trucks, Ferruginous Hawks are left out in the storm to fend for themselves.

It can get pretty rough out there. In fact, Ferruginous Hawk nests can actually blow right out of the tree, usually killing the eggs or young. Our nest monitoring program has found that 20% of nest failures are due to nests blow-outs and climate change scientists are worried that this will happen more often when storms become more frequent and more severe.


World’s Biggest Ferruginous Hawk Nest

FEHA nest sculpture in Leader, SK.  Photo: Janet Ng

FEHA nest sculpture in Leader, SK. Photo: Janet Ng

Some of our field work takes up to far flung places in Alberta and Saskatchewan.  Leader, Saskatchewan has several claims-to-fame including nine Larger Than Life sculptures that are scattered through town.

Our favourite, of course, is the 15 foot Ferruginous Hawk nest that resides on main street.

FYI, they frown upon climbing into the nest.

Burrowing Owl family in Leader, SK.  Photo: Janet Ng

Burrowing Owl family in Leader, SK. Photo: Janet Ng

Birds and Windows Project

Birds face many threats when they come into contact with urban populations. One of the leading causes of avian mortality in cities is window collisions. In Canada it is estimated 25 million birds are killed each year as a result of bird window collisions.

The Birds and Windows Project was developed to use citizen science and active participation to continue to identify the factors that affect collision risk at residential homes.

Bird window collision evidence on the University of Alberta campus

Last fall Environment Canada released a report on the leading causes of human related bird deaths, with collisions with houses or buildings tied for second spot with power lines, collisions and electrocutions, behind  domestic and feral cats. Most studies on window collisions have focus on tall skyscrapers but based on the sheer number of houses compared to tall skyscrapers, houses represent 90 % of the mortality.  More work is needed; only four studies in the past have focused on bird window collision mortality at houses.

To better understand what can be done to reduce bird window collisions at your home, the University of Alberta has developed this project to actively involve YOU in data collection. We are asking you to think about bird window collisions you have observed in the past and would like you to regularly search around your residence for evidence of bird window collisions in the future.

This project is Canada wide and will be running at least until the end of 2014.

To get involved in the Birds and Windows Project, visit: