Course:CONS200/2023WT1/Impacts of Domestic Cats (Felis Catus) on Urban Biodiversity Conservation

Urban cat waking up from a nap

The domestication of cats began roughly 10,000 years ago with the onset of agriculture. Researchers suggest the main reason cats built a relationship with humans was to acquire food scraps and capture mice for nourishment. The most prominent predator in numerous urban ecosystems are domestic cats (Felis catus). In cities, predation rates of their primary prey, small mammals, birds, reptiles, and fish, are heavily influenced by domestic cats. Feline predation does not necessarily arise from a lack of access to food, rather hunting is inherent. In addition to predation, competition with other species for prey, land, and/or habitat control can reduce biodiversity in urban areas. An example of this may be a cat’s unnecessary consumption of mice taking away meals from a fox. Overconsumption of prey is not the only way cats impede on native species, they can also breed with wild felines, which can eventually lead to a loss of genetic diversity. Furthermore, domestic cats can be responsible for disease transmission, such as toxoplasmosis and rabies, across multiple species of vertebrates.

Managing the impacts of household cats on city ecosystems is being explored through various techniques. Currently, restricting the movement of cats in urban areas and neutering domestic populations are the most effective methods in managing the problem. Implanting microchips in cats to monitor their movement and behaviours within cities will allow owners to keep their pets out of highly biodiverse or sensitive areas of urban environments. A final method of changing a cat’s outdoor action in cities is through behaviour modification and training conducted by the owner. Public backlash is the most prominent obstacle in implementing strict policy to reduce the effects of domestic cats on urban biodiversity. Lack of knowledge about the negative effects fuzzy felines pose to ecosystem stability drives the issue of public collaboration.

How do Domestic Cats Effect Urban Biodiversity

Domestic cat (Felis catus) playing with a lizard

Domestic cats (Felis catus) are affecting urban biodiversity in more ways than one. Domestic cats are responsible for hundreds of native species deaths, specifically birds, as well as disease transmission, effects on competition, and hybridization.

Predation

Domestic cats have adverse consequences on bird populations, predation by domestic cats dramatically reduces population persistence in many native species. Research shows that 50-80% of pet cats that are allowed to be outdoors are actively hunting prey. The amount of prey that domestic cats are catching is astronomical, in the Netherlands alone 141 million animals are killed by cats each year. Domestic cats have become an apex predator in almost all urban and suburban areas around the world.

It is hard to denounce whether or not the prey caught by domestic cats are healthy individuals or are predisposed. However overall, globally predation by domestic cats has resulted in the extinction of at least 63 species and further put 367 species at risk of extinction. Thus proving the above analysis a moot point as cats have resulted in vast changes to species composition around the world.

Effects on Predation

Domestic cat (Felis catus) predation can be affected by a few conditions, including age and time of day. A study found that younger cats under the age of 1 were found to bring almost double the amount of prey home compared to older cats. Furthermore, the height of prey caught is throughout the spring to early fall and drops during the winter months. This is most likely to do with an increase in activity of most bird and rodent species in these months due to breeding. Overall, the predation is not constant throughout the year or a cat's lifetime. There are fluctuations to the amount of prey caught due to the time of the year as well as the individual cats maturity. How the cat is looked after can also affect its likelihood to hunt. Cats that are not fed properly at home will look for this food source elsewhere .

Disease Transmission

Predation is not the only negative consequence that domestic cats have on urban biodiversity. Cats carry many diseases which can be transmitted to other animals such as toxoplasmosis, which causes significant mortality rates for vertebrate species. Toxoplasmosis is a disease caused by a single celled parasite Toxoplasma gondii, that can be linked to cases of nervous system disorders, cancers and other life-threatening conditions. The parasite can be transmitted through cat feces into water ways and reach marine environments. Once in the ocean it has shown to be a major cause of death of southern sea otters, Enhydra lutris nereis, off the coast of California . Recent UBC research found that domestic cats are the ones to blame in transmitting Toxoplasma gondii in dense urban areas . One infected cat can release up to 500 million eggs in just 2 weeks, the eggs can then live in soil and water ways for years .

Florida Panther (Puma concolor coryi)

Toxoplasmosis is not the only disease transmitted by cats. An outbreak of feline leukaemia virus in the early 2000s is known to kill 5 members of the endangered Florida panther, Puma concolor coryi . The Florida panther is one of the most endangered mammals on Earth with only 70-100 members recorded when the outbreak took place . Thus, domestic cats are not only killing small prey species but have the ability to cause mortality in all levels of the food chain.

Competition

Furthermore, free roaming Domestic Cats also create competition for resources with native predators as cats themselves are not a native species to North America. When in large numbers such as in dense urban environments cats reduce the prey available for predators such as hawks and weasels. Every free roaming cat is taking necessary food, shelter, and space from important native species.

Hybridization

Wildcat (Felis silvestris)

Hybridization is when domestic cats mate with other wild cat species. The effects of hybridization can be detrimental for native species as it can result in extinction. For instance, hybridization can lead to a process called 'genetic swamping'. This is when breeding with wild cats leads to too many hybrids to a point when there are no more remaining native individuals. In Europe, the anthropogenic spread of domestic cats and their contact with wildcat species is listed as one of the greatest threats to survival for wildcat populations.

Indirect Consequences of Hybridization

Hybridization has many indirect effects. Many breeders will purposely breed domestic cats with wildcats because of the aesthetic they percieve. However, in ecosystems that would not normally have a wildcat population this can be detrimental. Due to their wild instincts, hybrid cats are much better at hunting resulting in even more predation of native bird, reptile and mammal species. Furthermore, no rabies vaccines work on hybrid species. This will again further the issues of disease spread that was discussed above. Hybrids are able to spread rabies to native animals and this will have destructive effects on ecosystem health and populations.

Current Remedial Actions

There have been many remedial actions being proposed and implemented throughout the world in attempts to reduce the impacts of domestic cats on urban biodiversity. These attempts, however, have been difficult to enforce and move forward with due to biases skewed in favour of the cats as they are a beloved, household pet.

Restricting Cat Movement

Indoor cat in the city

A majority of the actions against cats have been focused on curtailing cat movement throughout the cities. Implementations of cat fencing have proved to be beneficial but are quite costly and can be destroyed easily during extreme weather conditions . As well, enforcing of cat-free zones and curfews have worked well to decrease predation rates in Australia but there has been backlash from cat owners and institutions, such as the Texas A&M employees, about this as they do not believe in the threat that cats pose to biodiversity . A few simple practices that cat owners could use would be putting on cat bells or cat bibs to decrease success rates of cat predation .

Neutering as Population Control

With the rising of cats' population all over the world, harmful effects of cats on their potential to affect populations through predation by intimidation, fear, disease transmission, moreover reduced abundance of prey population may have pushed policies to reduce and hinder the increase of cat populations. Neutering has been a worldwide solution for reducing cat populations' that work and even encouraged by veterinarians, claiming that it also offers health and behaviour benefits including reducing aggression between cats and increasing cats' affection towards people and enhancing their suitability as pets. In addition, neutered cats have a lower risk of contracting some infectious diseases.

Veterinarian doing a check up on a cat

TNVR (Trap-Neuter-Vaccinate-Return)

TNVR (Trap-Neuter-Vaccinate-Return) Program is thought to be one of the most effective ways to help with the abundance of cat overpopulations. This program is proven to have the potential to reduce, and even eliminate, free-roaming cats at the colony or neighborhood level if done with sufficient intensity and targeted geography. TNVR programs have also been shown to produce significant reductions in a shelter's feline intake and number of cats killed. It evolved in the U.S. after the city of Jacksonville, Florida, became the first city to introduce it in a shelter setting in 2008. This program is usually done by animal rescue communities and organizations (e.g VOKRA in Canada or Peggy Adams Animal Rescue League in the US).

Future Management

Public Controversy

One of the barriers preventing effective, logical solutions to the issues cats pose would be pushback from the public. Many cat owners and general civilians are unaware of how much cats threaten the wildlife in the urban areas that they are allowed to roam . Oftentimes this is due to the lack of education and awareness because the amount of prey caught is not always obvious to the owners . Though cats catch few to no prey, the few times that prey is caught can add up to big portions of populations that are already struggling to survive . This is not obvious to the average cat owner and so education seems to be necessary in order to garner the population's cooperation with preventing cat predation in urban environments. However, many UK studies concluded that even when cat-owners were faced with factual evidence of cats being harmful, many of their views remained the same .

Community Education and Collaboration

To understand the effects of cat predation on the urban environment, community engagement, and education programs to raise awareness might be effective for the larger population. At the very least, information should be easily accessible to pet owners, especially in adoption centers where soon-to-be pet owners might be present. Explanations of cats' behavior before adoption or previous research requirements before adopting cats should be mandatory. As cats are one of the most common domestic pets, collaborative efforts between local governments, environmental organizations, and pet owners could promote responsible cat ownership and wildlife conservation in the future.

Compulsory Microchipping

A microchip is a small radio-frequency identification device (RFID) enclosed in an inert capsule and implanted into the subcutaneous tissue of an animal (usually a dog, cat, or horse) to provide permanent electronic identification of the animal. Since microchips can be read by specialized scanners with a very high degree of accuracy, originally, it is used to know the locations of pets in real life to avoid lost animals. But this could also be used to mitigate cat predation in urban settings. By monitoring pet cats' location in real-time, owners can be more assured to let them roam outside and be able to redirect them to avoid high biodiversity locations, discouraging predation on those locations. However, this action will need active participation by owners since they will be the ones responsible for monitoring cats' actions. It would be best to have notifications for owners to know whenever cats are nearing certain locations. Compulsory microchipping will be beneficial for other uses too, through the use of specialized databases, the number read from the microchip can be linked to owner details and to animal health records, such as vaccination and neuter status, which will be convenient for pet owners to be frequently updated about their pet's living condition.

Well-behaved cat

Cat Behavior Modification with Training

The quality and quantity of human-animal interactions experienced by cats are both relevant to their welfare outcomes in various settings. A human-animal relationship can be said to exist if a number of repeated interactions between the animal and human occur, eventually allowing each to make predictions about the other’s behavior. In human-animal relationships, the human generally dictates the number and nature of interactions and hence the relationship, while the animal more often simply reacts to the human’s actions. Although we can't possibly predict cat's behavior, it would be best to assume that all cats, whether trained before or not, will have their natural predatory instinct, which includes predatory instinct on a niche group of prey species regularly if not handled properly. To effectively solve this problem, training behaviors could start from their own home, with their closest human companion. We could use the concept of classical conditioning, where pet owners use a specific stimulus to elicit a response to reduce aggressive response, avoiding active predatory behavior. Although more positive reinforcement training or interactive toys that simulate hunting experiences without living prey could also be explored, feeding behavior seems to also be positively correlated with predatory instinct, so the ability to feed cats regularly should be a requisite for every domestic cat's owner.

Conclusion

Ever since cats became domesticated about thousands of years ago, they have been predating small mammals. Over the course of their relationship with humans, cats have not lost their primal instinct to kill. Even when urban cats are adequately fed in their homes, sometimes, they bring home carcases of small mammals and/or birds to their owners. In doing this it becomes clear that nowadays, domestic cats do not solely predate for survival. Domestic cats have numerous effects on urban biodiversity. Their predation of mice, birds, fish, and reptiles has reduced the population sizes of these species for other predators to consume. The species these domestic cats are predating on are some of the other predator’s primary prey, therefore, competition arises for what nourishment is available. In addition to competition, domestic cats continue to be responsible for the transmission of numerous diseases amongst various vertebrate species.

In efforts to manage the negative effects of household cats on urban biodiversity, their movement within cities is being restricted and they are being neutered. Furthermore, microchipping cats to observe their movement and training them to avoid biodiverse areas have also offered reliable solutions. Lack of awareness surrounding how domestic feline friends harm biodiversity has created public backlash against putting these practices into effect.