Background

Domestic cats (Felis catus) have thrived and multiplied as cherished pets, unwanted strays and semi-wild predators. Although generally overlooked as a conservation problem, domestic cats may have dramatic impacts on native wildlife species by preying on small mammals and birds and competing with native predators for food. Problem cats generally fall into two categories: feral cats and free-ranging cats. Feral cats are the semi-wild offspring of domestic cats, usually several generations removed from human ownership. In contrast, free-ranging cats are kept and fed by humans, but they are free to hunt away from their homes. There are approximately fifty million feral cats in the United States and they have doubled in number during the past twenty years. Nationwide, cats are estimated to kill one to five billion small mammals and hundreds of millions of birds each year. Consequently, they may reduce the number of prey available to native predators such as hawks, owls and bobcats.

Objectives

The ecology of feral and free-ranging cats is poorly understood, therefore my objectives were to:
    1) Investigate the activity patterns of cats,
    2) Quantify habitat use by foraging cats, and
    3) Estimate home-range size and maximum daily movements.

Methods

My study areas were the Hurricane Creek Habitat Area, a state-owned area managed by the Illinois Department of Natural Resources, located southeast of Charleston and the Douglas-Hart Nature Center located near Mattoon. Cats were trapped by using soft cat food as bait. Trapped cats were anesthetized with ketamine and xylazine for handling, sexed, weighed, aged and equipped with radio-collars (Figure 2). Activity patterns were quantified by locating selected cats every fifteen minutes during two-hour periods throughout the day by using a directional antenna and Global Positioning System (GPS) receiver. Locations were recorded as Universal Transverse Mercator (UTM) coordinates on aerial photographs. During this time I recorded the cat’s activity, such as hunting or sleeping. I assumed that cats were hunting if they were continually moving and away from their home. I also recorded  the habitat type that the cat occupied during each fifteen minute interval. Habitat types were categorized as forest, forest edge, farm yard, crop field, crop edge, old field, roadside and grassland. Habitat preference was tested by comparing observed use with expected use based on the proportions of each habitat type on the study areas. I estimated the minimum convex polygon (MCP) home range size using McPAAL software.

Results

Cats were nocturnal with the majority of their activity occurring from 7PM to 7AM. Hunting began at dusk and peaked before 1AM (Figure 4). Cats preferred hunting in forests and along forest edges. In contrast, crop fields, grasslands and roadsides were used less often than expected (Figure 5). Summer home-ranges were smaller than expected, averaging 3.6 ha. Most foraging occurred within

1 km of the cat’s home (Table 1).

Conclusions

    1) Feral and free-ranging cats are primarily nocturnal. Most hunting occurs between dusk and 1AM.
    2) Cats preferred to hunt in forest and forest edge habitats and avoided crop fields, grasslands and roadsides.
    3) Most cats lived near houses, barns and outbuildings. Home ranges were small. Few cats hunted more than 0.5 km from their homes.
    4) Consequently, cats are most likely to impact birds and small mammal populations near farms and human dwellings.