Animal Ethics funded a newly published study about causes of death, illness, and injury to wild animals in Canada

20 Jul 2023

A paper examining causes of morbidity and mortality in wild animals across Canada was recently published in the Journal of Wildlife Diseases, an important journal in its field internationally. This work was funded by Animal Ethics and conducted by researchers at the University of Guelph. There has been very little academic research on the situation of wild animals, which can inform actions aimed at helping them and reducing the harms they suffer. For this reason, promoting this kind of work has been one of Animal Ethics’s top priorities in recent years. We are happy to announce the publication of this work.

The findings reveal important information about anthropogenic harms and the prevalence of starvation and disease among wild animals near urban areas. Of particular note is the high number of admissions for starvation and emaciation in birds, even though birds generally have more access to human food waste in areas where humans live.

The results are not meant to provide insight into the total or relative numbers of various harms to wild animals who live far from humans, as the data is about animals living near human areas. However, its methods and approach can inspire further research focusing on animals living in distant areas. The paper was authored by Meagan King and funded by a postdoc grant from Animal Ethics, together with animal scholars Jolene Giacinti, Sara Dubois, Stéphane Lair, Jane Parmley and Claire Jardine.

Studies of this kind are uncommon, and this ground-breaking work brings much-needed attention to threats to wild animals living in and near areas occupied by humans. In a previous study, we looked at factors affecting the wellbeing of animals in urban areas, with a more detailed look at life chances for animals of five different species.

This broad study analyzes 163,000 medical records for wild animals admitted to rehabilitation centers and pathology labs across Canada between 2009 and 2019. It integrates data from diverse regions and sources, providing a multi-faceted look at risks to Canadian wild animals. The results show high rates of injury, disease, and mortality among wild animals near human-occupied areas.

Ranking highest among causes of harm was trauma, accounting for 44% of animal deaths and 48% of rehabilitation admissions. Much of this trauma stemmed from collisions with vehicles and windows, together responsible for 12-18% of recorded cases. Predation by companion animals, especially by cats among fledgling songbirds, hummingbirds, and bats, was also a major contributor to trauma admissions. Other sources included shootings, entanglement, and attacks by off-leash dogs. While trauma affected all taxa, infectious diseases predominantly impacted mammals, causing 27% of mammal deaths. Meanwhile, emaciation and starvation especially affected birds (23% of bird deaths).

28% of all wild animal rehabilitation admissions consisted of orphaned juveniles, particularly young mammals and water birds. Other common reasons for admission were animals found in unsuitable locations, nest or habitat destruction, and capture of wild animals as pets. Many admissions were due to uncertain circumstances. Disturbance of bat hibernation habitats led to many admissions of bats active in winter. Additionally, researchers found high rates of intentional killing of wild animals perceived as threats, including 22% of admitted mammals. However, 19% of those killed had no detected health or behavioral issues.

While the data provides insights into which types of wild animals near urban areas are most vulnerable, researchers acknowledged limitations, including under-detection of natural mortality. Speculative and incomplete diagnoses are another limitation. At rehabilitation centers, animals are sometimes admitted for one reason, but the underlying cause may be different. For example, an animal might be confused or too weak to cross a road and, as a result, they are hit by a car. Such cases would likely be admitted as trauma without revealing more about the condition of the animal at the time of the accident.

Despite these limitations, the study clearly demonstrates the substantial impacts of trauma, disease, starvation, and orphaning. It also highlights the high rates of humans killing wild animals in terrible ways, even when there is no apparent reason for conflict. Targeted mitigation strategies could help reduce these impacts through measures like wild animal crossings over roads, bird-safe architecture, and public education. Additional integrated data could build a more comprehensive picture of threats to animal health to inform policy decisions.

You can read the full text of the paper online here:

Using wildlife rehabilitation and postmortem data to identify key causes of morbidity and mortality impacting the health and welfare of free-living wild animals in Canada

This is the abstract of the paper:

The health and welfare of wild animals are of increasing concern, yet there are very few large-scale data syntheses examining how causes of wildlife morbidity and mortality vary across time, space, and taxa. Records for 18,540 animals submitted to the Canadian Wildlife Health Cooperative (CWHC) (2009-19) and 144,846 animals admitted to 19 wildlife rehabilitation centers (WRCs) (2015-19) were evaluated to 1) identify the main causes of morbidity and mortality for Canadian wildlife and 2) assess the utility and complementarity of these two data sources to further our understanding of wildlife health. The CWHC cases (mortality) were examined by pathologists and grouped by the presence or absence of five diagnostic categories: trauma, emaciation, infection or inflammation, toxicity, and other. These CWHC animals were also classified as “killed due to real or perceived human-wildlife conflict” based on finder history. The WRC admissions were categorized by health issue (according to intake records) and based on reported or observed situational reasons for admission: parental loss, unsafe or unsuitable location, nest or habitat disturbance, illegal possession, and abnormal behavior. For both datasets, the main reason for submission or admission was trauma (44 and 48%, respectively), especially vehicle collisions (7 and 11%) and window or building strikes (5 and 7%). Many other WRC admissions were due to parental loss (28%), cat attacks (6%), and immature animals being found in unsafe or unsuitable locations (6%). Most other CWHC mortalities were caused by infections (27%) and emaciation (23%). Relatively few birds, amphibians, and reptiles submitted to CWHC were killed due to human-wildlife conflict, but 22% of mammals were killed for this reason, highlighting the taxonomic differences in the perceived threat of wildlife to finders, and therefore their response. Together, these data sources highlight key issues impacting the health and welfare of wild animals in Canada.

The paper full citation reference is this: King, M.; Giacinti, J.; Dubois, S.; Lair, S.; Parmley, E. J. & Jardine, C. M. (2023) “Using wildlife rehabilitation and postmortem data to identify key causes of morbidity and mortality impacting the health and welfare of free-living wild animals in Canada”, Journal of Wildlife Diseases, 59(1), 93-108.

For more general information about this topic, see our related work that takes a detailed look at what life is like for wild animals and what we can do to help them.

You can also read our ebook about wild animal suffering here.