Weekly Reports

June 20 – 26, 2024

Posted | filed under Weekly Reports.

Last week we discussed how to responsibly enjoy wild spaces with our dogs. Yet dogs are not the only pet that harms wildlife. In Canada, the largest direct human-caused killer of birds is domestic cats, whose depredations far exceed the deaths caused by collisions with windows, wind turbines, and cars combined 1. Bird are especially vulnerable to pets this time of year as their babies leave the nest, but still cannot fly well enough to escape a determined predator 2. As with dogs, time spent avoiding cats is time taken from incubating and feeding young.

Above: The top human-linked activities/objects that directly kill Canadian birds alive today 14. Since estimating population declines due to indirect sources (habitat loss, climate change, etc.) are exceedingly difficult to estimate, these threats are not included here.

Free-roaming cats kill between 100 and 350 million birds each year in Canada 1, and those that survive must migrate through the United States, where a further 1.3 to 4.0 billion birds fall prey to cats annually 3. These numbers are derived from many careful scientific studies whose methods are geared towards generating a conservative estimate of bird mortality; the actual number of birds killed by cats is likely even larger 4, and would include birds that are injured by cats and die later, and nestlings who starve to death after their parents are killed.

As awareness of the dangers posed by house cats to wildlife has grown, there has been a growing call for cat owners to keep their pets indoors 5. Slave Lake bylaws even prohibit cats from roaming “at large” 6. But some people find it hard to believe that their cat could be a threat to wildlife 7. After all, house cats are not the only animals that prey on birds, so why should they be singled out?

Above: Hunting birds is in a cat’s natural instincts, but cats are not a part of North America’s natural environment. A simple leash and harness on a cat run keep Robyn Perkins’ cat, Marceline, from reaching the bird feeder or hiding effectively.

It is important to realize that, while hunting is in a cat’s nature, cats themselves are not natural predators for wild birds. House cats are an introduced species in North America, one that would not be present if we had not brought them here 8. Because we feed and care for them, they exist in numbers far higher than could ever be attained by native predators 9. Cats also occupy broad habitat types so that no where is safe from this introduced predator 9.

Being fed and well cared-for does not stop a cat from hunting. A study that placed video cameras on pet cats found that they abandoned fully half of their prey where they had killed it rather than eating it or even bringing it home 10.

Loving birds and loving cats is not a contradiction 11, 12. Many of the staff here at the LSLBO and the Boreal Centre for Bird Conservation share their lives with beloved pet cats, but none of us would ever let them roam outside unsupervised! Instead, our cats enjoy the outdoors at the end of a leash, or from inside a protected outdoor enclosure. In this way, not only are birds and other animals kept safe from our pets, but our pets are kept safe from cars, wild animals, dogs, diseases, and parasites 13. While keeping our cats indoors is not the ‘magic bullet’ that will save wild birds once and for all, it is still a simple step that we can all take towards improving the lives of the birds we love, and the cats who love us.

  • Fiona, a strictly indoor cat, plays with fish toys.
  • Henri enjoys the safety of being high up in a cat tree.
  • Henri also has a special backpack for touring the town.
  • Marceline was fixed after adoption – a service paid for by the local shelter.
Above: There are many ways to own cats without harming our local ecosystems. Cats often want to explore outside simply because they are bored, so having a big play session with your cat to distract them from meowing at the door can help ease them into a new life as an indoor-only cat. Cat trees to climb and hide on make happy indoor kitties, especially when located near windows. At minimum, all pets should be fixed to decrease populations and take pressure off the environment and animal shelters.

Reprint of a 2019 report by Sachi Schott, LSLBO Assistant Bander; a few updates by Robyn Perkins LSLBO Bander-in-Charge

Literature Cited and Additional Reading:

  1. Blancher P. 2013. Estimated number of birds killed by house cats (Felis catus) in Canada. Avian Conservation and Ecology 8(2): 3. http://dx.doi.org/10.5751/ACE-00557-080203
  2. Timm M, Kime NM. 2020. Effects of cat and dog interactions on urban wildlife admitted to a wildlife center in Wisconsin. Journal of Young Investigators 38(6): 61-66. http://doi.org/10.22186/jyi.38.6.61-66
  3. Loss S, Will T, Marra P. 2013. The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications 4: 1-7. https://dx.doi.org/10.1038/ncomms2380
  4. Loss S, Will T, Longcore T, Marra P. 2018. Responding to misinformation and criticisms regarding United States cat predation estimates. Biological Invasions 20(12): 3385-3396. http://doi.org/10.1007/s10530-018-1796-y
  5. Dauphiné N, Cooper R. 2009. Impacts of free-ranging domestic cats (Felis catus) on birds in the United States: a review of recent research with conservation and management recommendations. Proceedings of the Fourth International Partners in Flight Conference: Tundra to Tropics, 205-219.
  6. Town of Slave Lake. Bylaw # 12- 2015. https://www.slavelake.ca/DocumentCenter/View/240/Bylaw-12-2015-Responsible-Pet-Owners-PDF
  7. McDonald J, Maclean M, Evans M, et al. 2015. Reconciling actual and perceived rates of predation by domestic cats. Ecology and Evolution 5(14): 2745-2753. http://dx.doi.org/10.1002/ece3.1553
  8. Loyd K, Hernandez S, Carroll J, et al. 2013. Quantifying free-roaming domestic cat predation using animal-borne video cameras. Biological conservation 160: 183-189. https://dx.doi.org/10.1016/j.biocon.2013.01.008
  9. Hamer RP, Gardiner RX, Proft KM, Johnson CN, Jones ME. 2020. A triple threat: high population density, high foraging intensity and flexible habitat preferences explain high impact of feral cats on prey. Proceedings of the Royal Society B. 288(1942): https://doi.org/10.1098/rspb.2020.1194
  10. About the Issue. 2021. Cats and Birds. Retrieved September 7, 2021, from https://catsandbirds.ca/about/
  11. Rastogi T. 2017. Uniting for cats and birds. Humane Canada. Retrieved September 7, 2021: https://humanecanada/2017/07/28/uniting-for-cats-and-birds/
  12. Indoor Cats vs. Outdoor Cats. 2016. American Humane. Retrieved September 7, 2021: https://www.americanhumane.org/fact-sheet/indoor-cats-vs-outdoor-cats/
  13. Tan S, Stellato A, Niel L. 2020. Uncontrolled outdoor access for cats: an assessment of risks and benefits. Animals 10: 258-271. https://dx.doi.org/10.3390/ani10020258

14. Sources of mortality estimates used in chart:

HUMAN CAUSELOWAVERAGEHIGHSOURCE
Cats105,000,000/204,000,000/348,000,000Blancher P. 2013. Estimated number of birds killed by house cats (Felis catus) in Canada. Avian Conserv Ecol. 8(2). doi:10.5751/ACE-00557-080203.
Feral cats49,000,000/116,000,000/232,000,000Blancher 2013
Rural pet cats12,000,000/42,000,000/102,000,000Blancher 2013
Urban pet cats7,000,000/35,000,000/108,000,000Blancher 2013
Window strikes16,100,000/24,900,000/42,200,000Machtans CS, Wedeles CHR, Bayne EM. 2013. A First Estimate for Canada of the Number of Birds Killed by Colliding with Building Windows. Avian Conserv Ecol. 8(2). doi:10.5751/ace-00568-080206.
Transmission lines2,500,00016,400,00025,600,000Rioux S, Savard JPL, Gerick AA. 2013. Avian mortalities due to transmission line collisions: a review of current estimates and field methods with an empahsis on applications to the Canadian electric network. Avian Conserv Ecol. 8(2). doi:10.5751/ACE-00614-080207.
Vehicle collisions8,900,00013,800,00018,700,000Bishop CA, Brogan JM. 2013. Estimates of Avian Mortality Attributed to Vehicle Collisions in Canada. Avian Conserv Ecol. 8(2). doi:10.5751/ace-00604-080202.
Agricultural mechanical operations (mowing, tilling, seeding, harvesting) 2,200,000 Tews J, Bert DG, Mineau P. 2013. Estimated Mortality of Selected Migratory Bird Species from Mowing and Other Mechanical Operations in Canadian Agriculture. Avian Conserv Ecol. 8(2). doi:10.5751/ace-00559-080208.
Sport hunting2,000,0002,190,0002,380,000Government of Canada. Average waterfowl harvest by hunters in Canada 2016 to 2018. National Harvest Survey Database. Modified 2019-06-30. https://wildlife-species.canada.ca/harvest-survey/P003/A001/?lang=e
Forestry616,0001,350,0002,090,000Hobson KA, Wilson AG, van Wilgenburg SL, Bayne EM. 2013. An estimate of nest loss in Canada due to industrial forestry operations. Avian Conserv Ecol. 8(2). doi:10.5751/ACE-00583-080205.
Communication towers 220,649 Longcore T, Rich C, Mineau P, MacDonald B, Bert DG, Sullivan LM, Mutrie E, Gauthreaux SA, Avery ML, Crawford RL, et al. 2012. An estimate of avian mortality at communication towers in the United States and Canada. PLoS One. 7(4):e34025. doi:10.1371/journal.pone.0034025.
Mining38,000190,000234,000Williams, Jeremy. 2010. Avian Incidental Take due to Mining Operations in Canada. Report Prepared by ArborVitae Environmental Services Ltd. for Environment Canada, Western Arctic Unit, Yellowknife. 32 pp. Unpublished.
Wind turbines20,00023,30028,300Zimmerling RR, Pomeroy AC, D’Entremont M V., Francis CM. 2013. Canadian estimate of bird morality due to collisions and direct habitat loss associated with wind turbin developments. Avian Conserv Ecol. 8(2). doi:10.5751/ACE-00609-080210.
Oil and gas exploration10,20017,00041,150Van Wilgenburg SL, Hobson KA, Bayne EM, Koper N. 2013. Estimated Avian Nest Loss Associated with Oil and Gas Exploration and Extraction in the Western Canadian Sedimentary Basin. Avian Conserv Ecol. 8(2). doi:10.5751/ace-00585-080209.