Domestic cat in the context of "Virginia opossum"

An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. Since the 20th century, invasive species have become serious economic, social, and environmental threats worldwide.

Invasion of long-established ecosystems by organisms is a natural phenomenon, but human-facilitated introductions have greatly increased the rate, scale, and geographic range of invasion. For millennia, humans have served as both accidental and deliberate dispersal agents, beginning with their earliest migrations, accelerating in the Age of Discovery, and accelerating again with the spread of international trade. Notable invasive plant species include the kudzu vine, giant hogweed (Heracleum mantegazzianum), Japanese knotweed (Reynoutria japonica), and yellow starthistle (Centaurea solstitialis). Notable invasive animals include European rabbits (Oryctolagus cuniculus), domestic cats (Felis catus), and carp (family Cyprinidae).

A feral cat or stray cat is an unowned domestic cat (Felis catus) that lives outdoors and avoids human contact; it does not allow itself to be handled or touched, and usually remains hidden from humans. Feral cats may breed over dozens of generations and become a local apex predator in urban, savannah and bushland environments, especially on islands where native animals did not evolve alongside predators. Some feral cats may become more comfortable with people who regularly feed them, but even with long-term attempts at socialization, they usually remain aloof and are most active after dusk. Of the 700 million cats in the world, an estimated 480 million are feral.

Feral cats are devastating to wildlife, and conservation biologists consider them to be one of the worst invasive species on Earth. They are included in the list of the world's 100 worst invasive alien species. Attempts to control feral cat populations are widespread but generally of greatest impact within purpose-fenced reserves.

In zoology, a crepuscular animal is one that is active primarily during the twilight period, being matutinal (active during dawn), vespertine/vespertinal (active during dusk), or both. This is distinguished from diurnal and nocturnal behavior, where an animal is active during the hours of daytime and of night, respectively. Some crepuscular animals may also be active by moonlight or during an overcast day.

A number of factors affect the time of day an animal is active. Predators hunt when their prey is available, and prey try to avoid the times when their principal predators are at large. The temperature may be too high at midday or too low at night. Some creatures may adjust their activities depending on local competition.

F1 hybrid (also known as filial 1 hybrid) is the first filial generation of offspring of distinctly different parental types. F1 hybrids are used in genetics, and in selective breeding, where the term F1 crossbreed may be used. The term is sometimes written with a subscript, as F₁ hybrid. Subsequent generations are called F₂, F₃, etc.

The offspring of distinctly different parental types produce a new, uniform phenotype with a combination of characteristics from the parents. In fish breeding, those parents frequently are two closely related fish species; however, in plant and animal breeding, the parents often are two inbred lines.

A purr or whirr is a tonal fluttering sound made by some species of felids, including both larger, wild cats and the domestic cat (Felis catus), as well as two species of genets and the Caquetá titi monkey (Plecturocebus caquetensis). It varies in loudness and tone among species and in the same animal. In smaller and domestic cats it is known as a purr, while in larger felids, such as the cheetah, it is called a whirr.

Although true purring is exclusive to felids and viverrids, other animals such as raccoons produce vocalizations that sound similar to true purring. Animals that produce purr-like sounds include mongooses, kangaroos, wallabies, wallaroos, badgers, rabbits and guinea pigs.

The domestic cat originated from Near-Eastern and Egyptian populations of the African wildcat, Felis lybica lybica. The family Felidae, to which all living feline species belong, is thought to have arisen about 12 to 13 million years ago and is divided into eight major phylogenetic lineages. The Felis lineage in particular is the lineage to which the domestic cat belongs.

Several investigations have shown that all domestic varieties of cats come from a single species of the Felis lineage, Felis catus. Variations of this lineage are found across the world, and until recently, scientists have found it difficult to identify exactly which region gave rise to the modern domestic cat. It is believed that many separate incidents in different places led to the creation of these breeds. More complications arose from the fact that wildcat populations are very widespread and are very similar to one another. These variations of wildcats interbreed freely with one another when in close contact, further blurring the lines between taxa. Recent DNA studies, advancement in genetic technologies, and a better understanding of DNA and genetics as a whole, have added to the evolutionary history of the domestic cat. Archaeological evidence has provided earlier dates for domestication than were previously suggested.