Literature Review

Our first study comes from the Journal of Nature Communications. Nature is a British scientific journal known for its prestige and high barrier to entry for its scientific papers.

So how exactly was this study carried out?

This study is what is known as a “meta-analysis”, which means that it is a quantitative attempt to look at the results of other studies on this same subject and draw larger conclusions based on what the previous literature says. This study does a lot of the heavy lifting in terms of analysis of existing data that we likely would have had to surmise for ourselves if this meta-analysis had not been conducted.

In summary, this study took the results of other experiments done in the past that looked into both feral and owned cats’ kill rates and gave us an estimate of the annual mortality rate of small mammals and birds as caused by cats.

This study finds that the rate at which cats kill birds and small mammals is likely much higher than was previously thought. This is because the statisticians, in this case, were accounting for the number of animals killed by unowned cats as well as the number of kills made by owned cats that are not brought back to the cat owner, as compared to previous studies where only the prey returned to the owner by the cat was counted. It was found that 1.3-4.0 billion birds and 6.3-22.3 small mammals are killed by cats each year.

This study was written in 2013, and it was a landmark piece of writing on this topic. Previously it was not known to this extent what sort of damage free-roaming felines do to the environment- though, since 2013, little has been done legally or conservationally to address this issue.

Study Two

Our second study looks at the legal side of addressing the problem of free-roaming cats. This study is from the British Ecological Society, the oldest ecological society in the world with an accompanying journal for members to host their findings in.

This study takes stock of the current legal literature on invasive species, a category under which domestic free-roaming cats fall. Lots of work has been done in many countries to protect native species from the negative effects that invasive species can have (over-hunting, flexible competition, habitat degradation, etc.) but these treatises have seldom been applied to domestic cats - likely as a result of human bias in favor of our favorite furry friends.

This writing identifies several international and national treaties that technically require the management and possible euthanization of feral domestic cats:

1979 Convention on the Conservation of Migratory Species of Wild Animals (CMS), Articles III(4)(c) and V(5)(e) (Parties: Africa, South America, European Union, Central Asia, and Australia)

1992 Convention for the Conservation of the Biodiversity and the Protection of Wilderness Areas in Central America, Article 24

1985 Protocol concerning Protected Areas and Wild Flora and Fauna in the Eastern African Region (East Africa Protocol), Article 7

1995 Protocol concerning Specially Protected Areas and Biological Diversity in the Mediterranean (Mediterranean Protocol), Article 13

1979 Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention), Article 11(2)(b)

This journal also addresses the issue of land protection treatises and specific animal protections, wherein the idea of managing feral cats may be necessary to protect the biodiversity of the identified land or animal but the literature does not specifically call for the management of invasive species within the text:

1972 UNESCO Convention concerning the Protection of the World Cultural and Natural Heritage

1971 Convention on Wetlands of International Importance especially as Waterfowl Habitat (Ramsar Convention)

1991 Agreement on the Conservation of Bats in Europe (EUROBATS)

Despite the fact that it seems that domestic cats fall under the category of a “threat to native biodiversity” within the purview of many of these treaties, little has been done to curb these cats' influence on the environment.

This is due to a combination of factors: practical feasibility, high management costs, legal questions regarding the management of owned cats, scientific uncertainty, and moral objections (on the part of cat owners).

For more information on the health concerns of free-roaming cats, click on the link at the top of the page labeled “Health”.