Feline Predatory Behaviour

Key Points

Felis silvestris is species native to Europe, and would exist here without human intervention. The impact of this species on wild bird and mammal species must be recognised. However, the relative size of the wild and feral cat populations, the impact of climate and public policy responsibilities for Trap-neuter-return (TNR) programmes should be taken into account when making recommendations to control the activities of pet cats. The impact on birds and mammals should not be generalised from countries where Felis silvestris is native to those where it is not (such as the USA), and vice versa. Increasing bird numbers by feeding birds and providing an insect and bird friendly garden does not appear to increase predation risk.

Prey Selection

Cats usually catch prey that is around 1% of their own bodyweight ; in one study 80% of reported prey caught was <50g in weight. In an observational study of feline predatory behaviour in a suburban nature preserve in New York (USA), small mammals and birds made up 52% and 23% of kills respectively, with an overall success rate for killing of 13% . Cats therefore show preferences in terms of their predatory targets, and are tolerant of a high failure rate in their predatory attacks.

The selection of prey target is also influenced by hunger; although hunger does not appear to affect the rate of hunting behaviour, cats will target larger and potentially more dangerous prey when they are hungry . The same study indicated that hunger increases the speed of killing behaviour, with satiated cats toying with prey for longer.

Apart from small mammals, birds and rodents, cats will also hunt and consume insects. Evidence for the specific nutritional contribution of insects to the diet of the cat is limited. However, insects (particularly spiders) are rich in taurine , which is an essential amino acid in cats.

Motivation to Hunt

The motivation to hunt, or at least engage with potential prey, is separate from hunger. A study by Adamec (1976) showed that cats will stop feeding from a food bowl in order to catch and kill a live rat that was introduced to the environment . In this study cats would then move the prey carcass close to the feeding area and return to eating the meal. Despite having killed the rat, cats showed almost no interest in eating it. The indication is that predatory behaviour is activated by stimuli, such as odour, prey size and movement, that are unrelated to stimuli connected with feeding or hunger.

The amount of time spent searching for food and hunting varies between pet and feral cats, with feral cats spending twice as much time per day (12 vs. 6 hours) on foraging

Hunting Strategies

Cats employ a variety of strategies when hunting, which are refined through experience. The two predominant strategies, "stalking" and "sit-and-wait", share the common feature of stealth; the cat attempts to get close enough to its prey so that it can make a final brief lunging attack at close range.

Cats appear to regularly use specific hunting locations where they have experienced a higher probability of encountering vulnerable prey. They move speedily between these locations, rarely deviating to take up unanticipated hunting opportunities. This implies that during an active period of hunting, cats prioritise their already established strategies for catching prey, rather than the discovery of new hunting sites or opportunistic exploitation of unexpected hunting opportunities. Hunting opportunities are time sensitive, due to the activity patterns of prey, but information about potential future hunting sites is available all the time.

At a hunting location the cat will systematically survey the area in search of evidence for the presence of prey. The cat’s hearing extends into the ultrasound, not only enabling the cat to detect scratching sounds and vocalisations of rodents but also to precisely locate prey using hearing alone. When such sounds are heard, active prey seeking is activated. Hunting is also activated by the movement of anything within the cat's field of vision that is around the correct prey size.

Sit-and-wait is the primary strategy for hunting rodents; once a cat finds an area where there are signs of prey, such as the scent of rodent urine close to a hole, it will then withdraw to a distance and wait. An attack occurs when prey moves into an open space away from a position of safety, and the cat judges that it will be able to mount a successful attack. During the last phase of a waiting period before an attack, the cat may perform paddling behaviour with its rear feet, which may prepare hind leg muscles to deliver maximum output during a dash and pounce.

If the attack is unsuccessful, then the cat will return to cover or explore the hunting area for another opportunity. If unsuccessful on several occasions, or no further opportunities are detected, then the cat will move on to another hunting area.

Stalking behaviour uses the cover of plants and bushes to move closer to prey, such as birds, that are more mobile and not tied to a burrow or shelter location. Cats will also predate young birds in the nest, dig moles out of their burrows and ambush young rabbits as they leave their burrows. However, the rate of predation of larger species, such as rabbits and squirrels, is low in domesticated pet cats compared with the rate of predation of rodents and birds.

Feeding preferences

Cats are obligate carnivores, and exhibit novelty preference; they are attracted to prey that is different from what they have eaten in the recent past. It is speculated that this “monotony effect” helps to ensure a balanced diet . Since cats hunt independently and catch only small prey that provide a single meal for an individual, they do not share food. Feeding is a solitary activity that carries no social meaning for cats. Cats eat 10-20 small meals each day, according to the availability of prey.

Latrine use During Hunting

Feral and wild cats use latrine sites that are located in their home range, but not their core territory. Latrine locations are chosen on the basis of location and substrate preference, both of which are learned during development. Latrine locations are away from hunting and feeding areas, but close enough to those places for the cat to be able to use them without a significant interruption of their other hunting and territory marking routines.

The Impact of Predation

Impact in the UK

In a study of domestic cat predation in the UK, the estimated mean predation rate was estimated at 18.3 per cat per year, with 65% of households reporting no prey brought back in a given year (falling to 22% when averaged over several seasons . The same study found that only 20% of cats returned 4 or more dead prey annually, and that the numbers of five bird species was not correlated with level of their predation. The predation of robins was only just significantly correlated with observed numbers (p=0.046). This may relate to some aspect of the vulnerability of this species when feeding and nesting, but the result would also become insignificant when measures are applied to counteract the problem of multiple comparisons in the study. There was also a significant inverse correlation between mean annual predation rate, cat population and housing density; the number of prey returned was lower in highly residential areas with a high cat population density.

Impact in Other Countries

Felis silvestris is a native species in most of Africa, Europe, central Asia, India, China and Mongolia. In these regions it forms a natural part of local ecology. Due to mutual tolerance between cats and humans, the density of cat populations can be much higher within and around human communities than in rural areas.

Felis silvestris is not a native species in the Americas or Australia, so the impact it might have on wildlife in these regions may be considered much more serious and intrusive to local ecology. For example, it is estimated that in the USA free-ranging domestic cats kill 1.4-3.7 billion birds and 6.9-20.7 billion small mammals each year .

This raises the issue of the impact of pet vs. feral populations. No accurate current estimate of the UK feral cat population is available, but the total cat population was estimated at 6 million in 1980, with 1.2 million feral cats. The current estimate of the UK pet cat population is 8 million, according to the Pet Food Manufacturers Association, and the population of feral cats is likely to be lower in 2014 than in 1980 due to active TNR and rehoming programmes over the last 30 years. The situation in the UK is quite different from Australia and the USA:

• Australia: 3 million pet cats, 10-20 million feral cats
• USA: 86.4 million pet cats, 60-100 million feral cats

Based on the most recent estimate, the UK feral cat population is perhaps 15% the size of the pet cat population, whereas in the USA these populations are similarly sized and in Australia feral cats outnumber pet cats by a factor of 10-20 to one.

Programmes to Control Cat Numbers

TNR programmes have been shown to be effective in a number of studies. Levy, et al showed a 66% reduction in population size over an eleven-year period in one free-roaming population. In the UK, nationwide trap and neuter programmes of this type have been in operation for more than a decade. In the UK and Germany, levels of neutering of pet cats are also high, which helps to limit population growth. Similar programmes are now also being run elsewhere by organisations such as International Cat Care in Portugal and Sudan.

However, the most significant factors in the maintenance of a large feral population are climate and the availability of prey. The temperate climate of Northern Europe limits kitten survival, compared to the warmer climate of Australia and parts of the USA. Australia also has a diverse population of prey species that have evolved in the absence of a predator equivalent to Felis silvestris.