Domestic and feral cats

 

Impact of predation by domestic cats Felis catus in an urban area.

This study investigated the impact of cat predation in urban areas, where most cats are likely to be present. It quantified the minimum number of animals killed annually by cats in a 4.2km2 area of Bristol, UK, by asking owners to record prey animals returned home by their pets. The potential impact of cat predation on prey species was estimated by comparing the number of animals killed with published estimates of prey density and annual productivity. Predator density was 229 cats/km. Five mammal, 10 bird and one amphibian prey species were recorded. Mean predation rate was 21 prey/cat/annum. The most commonly recorded prey species was the wood mouse Apodemus sylvaticus. Predation on birds was greatest in spring and summer, and probably reflected the killing of juvenile individuals. For three prey species (house sparrow Passer domesticus, dunnock Prunella modularis, robin Erithacus rubecula), estimated predation rates were high relative to annual productivity, such that predation by cats may have created a dispersal sink for juveniles from more productive neighbouring areas. The impact of cats on these species therefore warrants further investigation.

Urban bird declines and the fear of cats

This study investigated the lesser researched sub-lethal effects of domestic cats (Felis catus) on their prey. The study used a simple model combining cat predation on birds with a sub-lethal (fear) effect of cat density on bird reproduction. Results showed that these sub-lethal effects may be substantial for urban songbirds. When cat densities are as high as has been recorded in the UK, and even when predation mortality is low (e.g. o1%), a small reduction in fecundity (ability to produce offspring) due to sub-lethal effects (e.g. o1 offspring year-1 cat-1) can result in marked decreases in bird abundances (up to 95%). Thus, low predation rates in urban areas do not necessarily equate with a correspondingly low impact of cats on birds. Sub-lethal effects may depress bird populations to such an extent that low predation rates.

Fearing the feline: domestic cats reduce avian fecundity through trait‐mediated indirect effects that increase nest predation by other species

This study investigated the lesser researched sub-lethal effects of predation by non-native species. In the UK these include the domestic cat (Felis catus) and the grey squirrel (Sciurus carolinensis).

The study involved placing models of domestic cats, grey squirrels and control rabbits at active urban blackbird (Turdus merula) nests in Sheffield.

The domestic cat model consistently elicited high alarm calling rates. Exposure to domestic cats also reduced parental provisioning rates of blackbirds by over one-third relative to the rabbit control. There was no compensatory increase in food load size. The grey squirrel model induced similar but weaker effects.

The results therefore provided empirical evidence that quantifies the potential sublethal and indirect effects of predators (domestic cat and grey squirrel) on avian reproductive success.

Predation by domestic cats in an English village

This study investigated cat predation in the village of Felmersham, Bedforshire, UK. The prey items brought home by approximately 70 domestic cats (Felis cutus L) over the course of a year were recorded and, where possible, identified. A total of 1090 prey items (535 mammals, 297 birds and 258 unidentified animals) were taken, an average of about 14 per cat per year. Twenty two species of birds and 15 species of mammals were identified. The most important items were woodmice (1779, house sparrows (16%) and bank voles (14%).

Old cats of both sexes caught fewer prey over the year than young cats. Female cats on the edge of the village also caught more prey than female cats in intermediate or central areas of the village; male cats showed no such effect. The type of prey caught also varied with position in the village; ‘core’ cats caught proportionately more birds than ‘edge’ cats. There was some indication in the data that cats caught fewer prey in areas where cat density was highest, but this effect was impossible to disentangle from position in the village. Weather apparently influenced hunting success. Temperature had no direct influence, but fewer prey were caught in winter; cats also caught less on wet days and windy days.

Estimates of the number of house sparrows in the village at the start of the breeding season, and the number of sparrows known to have been caught by the cats, suggest that at least 30% of the sparrow deaths in the village were due to cats showing that domestic cats are major predators in this typical English village.

Reconciling actual and perceived rates of predation by domestic cats

This study investigated whether cat owners are aware of the predatory behaviour of their cats. Data was collected from 86 cats in two UK villages. The attitudes of 45 cat owners toward the issue of domestic cat predation was then evaluated in relation to the amount of prey their cat returns. The study also contributed to the wider understanding of physiological, spatial, and behavioural drivers of prey returns among cats.

Results showed an association between actual prey returns and owner predictions at the coarse scale of predatory/non predatory behaviour, but no correlation between the observed and predicted prey-return rates among predatory cats. Cat owners generally disagreed with the statement that cats are harmful to wildlife, and disfavoured all mitigation options apart from neutering. These attitudes were uncorrelated with the predatory behaviour of their cats. Cat owners failed to perceive the magnitude of their cats’ impacts on wildlife and were not influenced by ecological information. Management options for the mitigation of cat predation appear unlikely to work if they focus on “predation awareness” campaigns or restrictions of cat freedom.

Spatio-temporal variation in predation by urban domestic cats (Felis catus) and the acceptability of possible management actions in the UK

This study investigated the spatio-temporal variation in predation of domestic cats (Felis catus) in the town of Reading, UK. It enlisted cat-owners to record prey returned home to estimate patterns of predation by free-roaming pets in different localities within the town, and questionnaire surveys were used to quantify attitudes to different possible management strategies. Results showed that prey return rates were highly variable: only 20% of cats returned less than 4 dead prey annually. Consequently, approximately 65% of owners received no prey in a given season, but this declined to 22% after eight seasons. The estimated mean predation rate was 18.3 prey per cat per year but this varied markedly both spatially and temporally: per capita predation rates declined with increasing cat density. Comparisons with estimates of the density of six common bird prey species indicated that cats killed numbers equivalent to adult density on c. 39% of occasions. Whilst population modelling suggests that such predation rates could significantly reduce the side of local bird populations, most urban residents did not consider cat predation to be a significant problem. Collar-mounted anti-predation devices were the only management action acceptable to the majority of urban residents (65%), but were less acceptable to cat-owners because of perceived risks to their pets; therefore only 24% of cats were fitted with such devices. Overall, cat predation appeared to affect some prey populations, although further investigation of various key aspects of cat predation is warranted. Management of the predation behaviour of urban cat populations in the UK is likely to be challenging and achieving this would require considerable engagement with cat owners.

Predation of wildlife by domestic cats Felis catus in Great Britain

This study investigated the predation of wildlife by domestic cats (Felis catus) in Great Britain between 1 April and 31 August 1997.

A total of 14 370 prey items were brought home by 986 cats living in 618 households. Mammals made up 69% of the items, birds 24%, amphibians 4%, reptiles 1%, fish <1%, invertebrates 1% and unidentified items 1%. A minimum of 44 species of wild bird, 20 species of wild mammal, four species of reptile and three species of amphibian were recorded.

The number of birds and herpetofauna brought home per cat was significantly lower in households that provided food for birds. The number of bird species brought home was greater in households providing bird food. The number of birds and herpetofauna brought home per cat was negatively related to the age and condition of the cat. The number of mammals brought home per cat was significantly lower when cats were equipped with bells and when they were kept indoors at night. The number of herpetofauna brought home was significantly greater when cats were kept in at night.

Based on the proportion of cats bringing home at least one prey item, a British population of approximately 9 million cats was estimated to have brought home in the order of 92 million prey items in the period of this survey, including 57 million mammals, 27 million birds and 5 million reptiles and amphibians.

An experimental approach should be taken to investigate the factors found by this descriptive survey to influence the numbers of prey brought home by cats. In particular, investigation of potential management practices that could reduce the numbers of wild animals killed and brought home by cats will be useful for wildlife conservation, particularly in suburban areas.

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