Cats have excellent hearing and can detect an extremely broad range of frequencies. They can hear higher-pitched sounds than either dogs or humans, detecting frequencies from 55 Hz to 79,000 Hz, a range of 10.5 octaves, while humans and dogs both have ranges of about 9 octaves. Cats can hear ultrasound, which is important in hunting because many species of rodents make ultrasonic calls. However, they do not communicate using ultrasound like rodents do. Cats' hearing is also sensitive and among the best of any mammal, being most acute in the range of 500 Hz to 32 kHz. This sensitivity is further enhanced by the cat's large movable outer ears (their pinnae), which both amplify sounds and help detect the direction of a noise.
Since kitten diets are very high in calories, ingredients must be implemented to ensure adequate digestion and utilization of these calories. Choline chloride is an ingredient that maintains fat metabolism. Biotin and niacin are also active in the metabolism of fats, carbs and protein. Riboflavin is also necessary for the digestion of fats and carbohydrates. These are the main metabolism aids incorporated into kitten diets to ensure nutrient usage is maximized.
The domestic cat is a significant predator of birds. UK assessments indicate they may be accountable for an estimated 64.8 million bird deaths each year. A 2012 study suggests feral cats may kill several billion birds each year in the United States. Certain species appear more susceptible than others; for example, 30% of house sparrow mortality is linked to the domestic cat. In the recovery of ringed robins (Erithacus rubecula) and dunnocks (Prunella modularis), 31% of deaths were a result of cat predation. In parts of North America, the presence of larger carnivores such as coyotes which prey on cats and other small predators reduces the effect of predation by cats and other small predators such as opossums and raccoons on bird numbers and variety. The proposal that cat populations will increase when the numbers of these top predators decline is called the mesopredator release hypothesis.
Stage parodies of the musical have also been mounted in the West End and Off-Broadway. CAT – (THE PLAY!!!), a one-man show written by Jamie Beamish and Richard Hardwick, is a dark comedy about the fictitious life of Dave, a cat who was fired from the original London production of Cats on opening night. Starring Gerard McCarthy as Dave and with choreography by Arlene Phillips, the musical premiered at the 2014 Edinburgh Fringe Festival; it performed at various regional venues before making its West End debut at the Ambassadors Theatre in April 2017. Katdashians! Break the Musical!, a parody mashup of Keeping Up with the Kardashians and Cats by Bob and Tobly McSmith, premiered Off-Broadway at the Elektra Theatre in June 2016. All the song parodies of Cats were later removed after accusations of copyright infringement from Lloyd Webber's representatives, who claimed the songs were being used "to parody another subject matter entirely". Other stage shows that satirise Cats include Six Degrees of Separation, Angels in America, and The Musical of Musicals (The Musical!).
Following its Broadway debut, Cats has been staged extensively across North America. The first US national tour, Cats National I, launched at the Shubert Theatre in Boston in December 1983 and closed in November 1987. The opening night cast included Laurie Beechman playing Grizabella and Charlotte d'Amboise playing Cassandra; later replacements included Victoria Clark and Jessica Molaskey both playing Jellylorum/Griddlebone. This production was a "slow tour" that had lengthy engagements lasting for several months in each of the nine cities it visited. Cats National II, a separate sit-down production at the Los Angeles Shubert Theatre, ran from January 1985 to November 1986, and starred Kim Criswell and George de la Peña in the roles of Grizabella and Mistoffelees respectively. A third US touring company, Cats National III, ran for two years from September 1986 to September 1988. Notable performers in the third tour included Jonathan Cerullo as Skimbleshanks (1986) and Bill Nolte as Old Deuteronomy (1987).
The origin of the English word cat (Old English catt) and its counterparts in other Germanic languages (such as German Katze), descended from Proto-Germanic *kattōn-, is controversial. It was thought traditionally to be a borrowing from Late Latin cattus, 'domestic cat', from catta (used around 75 AD by Martial), compare also Byzantine Greek κάττα, Portuguese and Spanish gato, French chat, Maltese qattus, Lithuanian katė, and Old Church Slavonic kotъ (kot'), among others.