• Feline predatory behavior and most of the other attendant social behaviors that cats exhibit in human households have been only slightly changed in their structure and behavioral elements since the cat was “domesticated.”

• Because cats have had little direct influence on human economics (e.g., compared with that of hunting or herding dogs), there has been little intervention in their behavior by humans in the past hundred years (Young, 1985).

• Lack of selection for specific suites of behaviors (“behavioral domestication”) also may be reflected in the range of body sizes for present-day cats. In the wild, the range of body sizes of wild cat species greatly exceeds the range of size of wild dog species, and the range of body sizes of domesticated dogs far surpasses that reported for wild canids. In contrast, the size range of domestic cats is relatively small and well within the range of body sizes reported for their wild counterparts. Even large domestic cats are relatively small compared with their wild relatives.

• The lack of human intervention is supported by coat color patterns. One of the most common feline coat colors, the tabby, has radiated worldwide, yet this color is extremely similar to that of the European wildcat and Norwegian forest cat.

• Dogs, with whom we evolutionarily first formed true collaborative partnerships based on work

• Stock, animals such as sheep, goats, cows, chickens, and horses, who work for—not with—and/or serve us in the most utilitarian of contexts (i.e., providing food, fiber, compelled labor, et cetera)

• hardy,

• easy to tend,

• inborn liking of humans,

• comfort-loving,

• useful to people, and

• breed freely.

• Domestic cats reach puberty at about 10 months of age, although females born in the late spring may not cycle until the following year.

• Peaks in sexual activity occur from mid-January through March and from May to June in the Northern Hemisphere.

• Domestic cats are seasonally polyestrous and generally experience two cycles per year if not bred. Domestic cats can cycle every 3 weeks for several months—a fact that may help the most reluctant client to consider neutering the cat. Estrus in cats lasts 9 to 10 days in the absence of copulation but only 4 days if copulation occurs because cats are induced ovulators.

• Gestation in female domestic cats is approximately 63 days. This is longer, by 3 to 7 days, than the gestation period for F. sylvestris libyca (Hemmer, 1979; Schmidt et al., 1983). Litter sizes vary from 1 to 10 kittens with a mean of 4.5 kittens per litter. Most domestic cats allowed to do so have two litters per year (Liberg and Sandell, 1988), so one cat may produce an average of nine kittens a year. It is easy to understand how cities or neighborhoods with feral or semi-feral stray cat populations can be overwhelmed within a few years if the cats are left intact and have some access to shelter and food.

• Cats usually have eight nipples. Only three pairs of these nipples may produce sufficient milk to provide nourishment for a kitten, and the back nipples are preferred by kittens (Rosenblatt, 1976). Teat preference is established by 1 to 3 days, when present, and 80% of all kittens develop a teat preference (Rosenblatt et al., 1961). Kittens identify their mother and their preferred nipple using innate and learned olfactory cues (Raihani et al., 2009). The effects of such patterns on early nutrition and neurodevelopment have not been investigated, but for cats who may be compromised, this pattern may lead to some kittens being under-nourished, a pattern that contributes to increased reactivity and later problematic behaviors (Carola and Gross, 2010; Green et al., 2011).

• Females form stable matriarchal groups and may join in communal nests and engage in shared care and nursing (Macdonald and Apps, 1978; Macdonald et al., 1987). The queen moves the kittens if (1) the nest is fouled by feces, (2) undigested prey remains as the kittens get older, or (3) the site is disturbed by a strange male cat (Leyhausen, 1979).

• Queens stimulate kittens to eliminate by the anogenital reflex until 23 to 39 days, and kittens can usually eliminate voluntarily by 3 weeks. This developmental change may be associated with the queen’s mobile behaviors. Cats move kittens most frequently between 25 and 35 days (Schneirla et al., 1963).

• A familiar male may be such an integral part of the social group that he will guard against disturbances of foreign males (Macdonald et al., 1987). Communal nests may function in part to repel intruder males; however, they may also function to ensure that all kittens receive nourishment, should the number of nipples or the production of the milk be insufficient to support large litters. In a large farm study, males would provide care and succor for the kittens, if these males were residents within the larger social group (Macdonald et al., 1987).

• The presence of several reproductive males may facilitate communal care, including communal care provided by males (Kerby and Macdonald, 1988; Turner and Mertens, 1986). In such cases, no “dominant” male monopolizes all the matings (Natoli and de Vito, 1988). If males can neither monopolize all matings nor guarantee paternity, it might be advantageous for them to contribute to communal care. Many studies have shown that they are close to and will collaborate with females who are sisters and mothers (and possibly grandmothers) (Curtis et al., 2003). Males seldom provide lactating females with food or bring food directly to the kittens (Liberg, 1980), but they may care for the kittens, washing, guarding, and “nursing” them in non-nutritive relationships. It is now established that cats have “preferred associates” (Curtis et al., 2003), but these relationships go beyond the purported genetic ones.

• Females may further add to the stability of such social systems through their behavior during proestrus. During proestrus, females are attracted to males but are not receptive to their courtship behavior and reject attempts at copulation.

• It has been postulated that this is a device to enhance male-male competition (Bradshaw, 1992).

• This proestrus behavior also provides females with the opportunity to assess the staying power and abilities of males. In colonies that are sufficiently large, a proestrus that allows the females to evaluate males that are attracted to them would be one mechanism by which they could identify resident males and males with skills that may contribute to the best outcomes for the young.

• Finally, if the females are attractive to a number of males and all those males are part of the colony, that behavioral interaction could help facilitate communal care. In such cases, there may be an element of uncertainty of paternity, but copulation could then act to solidify social relationships where individuals “within” the group are treated differently than individuals considered “outside” the group. There are no data on whether animals known to the group are less likely to practice infanticide or more likely to provide communal care; there are even fewer data on whether the extent of a genetic or social relationship makes a difference for either of these factors. It has been postulated that males within colonies could be related. If this were the case, infanticide would not be an appropriate genetic strategy and would likely not enhance any single male cat’s genetic contribution because insemination by a brother would also be genetically advantageous.

• Relatedness has become a fascinating issue because ovulation is induced and estrus for any queen lasts only about 4 to 5 days (Natoli and de Vito, 1988, 1991; Paape et al., 1975; Schmidt et al., 1983).

• The issue of infanticide may be a concern in free-ranging groups and in breeding catteries. In domestic cats, weaning normally starts at approximately day 30 and continues through day 60 of the kitten’s life. If kittens die, regardless of the cause of death, the queen enters estrus approximately 15 days later (Liberg and Sandell, 1988). Under normal circumstances, cats might have two litters a year; if there is a litter death, the inter-birth interval can be only 133 days. Infanticide in domestic cats has been rarely observed directly (for exceptions see Dards [1983] and Liberg [1983]). An evolutionary argument can be made for the occurrence of infanticide in unstable groups or in groups that experience a cataclysmic change in the social structure. Females are induced ovulators, and the basis of social communal relationships may be influenced by the relatedness of the colony (Packer et al., 1991). There are no hard data to support this view of infanticide, and it would be inappropriate to assume that all of the social relationships within feline groups are driven by direct genetic relationships.

• The tactile sense is present early in gestation.

• Kittens are born unable to see but locomote freely.

• Kittens 2 to 4 weeks old exhibit plasticity physiologically and behaviorally. Exposure to low temperature can influence the rate of temperature regulation development at 2 weeks of age, but this effect is lost by 4 weeks (Jensen et al., 1980). This observation reinforces the extent to which early ontogeny is important in cats.

• Eye opening, between 10 and 14 days, is affected both by the environment and by genetics. Kittens of young mothers appear to open their eyes earlier than kittens of older mothers. Female kittens tend to open their eyes slightly earlier than males, but there also appears to be a strong paternal genetic effect on timing of eye opening (Bateson and Turner, 1988; Turner et al., 1986). This is probably not independent of the paternal effect on “boldness” (McCune, 1992).

• Electroencephalogram (EEG) activity in cats has periods of quiescence at 2 weeks, but EEG activity is continuous by 4 weeks. A peak in EEG activity occurs between 6 and 8 weeks, suggesting a neurodevelopmental shift, but amplitude and absolute power of EEGs do not reach approximate adult values until 20 to 24 weeks of age (Lewis et al., 2011).

• Kittens can recognize their mothers by sight and smell by the end of the third week of age (Martin and Bateson, 1988).

• By about 6 weeks of age, kittens demonstrate an adult-like response to visual and olfactory social stimuli, including silhouettes of adult cats and the scent of adult cat urine (Kolb and Nonneman, 1975). At about this time, the gape (flehmen) response to cat urine appears; this becomes fully expressed by 7 weeks of age. It has been postulated that the gape response, in its full adult form, is an indication of the maturation of the vomeronasal organ.

• The classic adult threat posture of tail down, arched back, and erect ears is often seen concomitant with the development of the gape/flehmen response and appears at about the same time (Kolb and Nonneman, 1975).

• Kittens can learn from firsthand, trial-and-error experience and by watching other cats. They are quicker at observational learning if they are watching their mother (Chesler, 1969; John et al., 1968), suggesting that there may be a role for very elegant, complex, and detailed signaling behaviors that have not been studied.

• The role of early social exposure in learning is also suggested by experimental results derived from maze problem-solving tests (Hebb-Williams closed field test). Alley cats achieve much higher scores than housecats, but they also make more errors (Pollard et al., 1971).

• Cats isolated from other cats from birth until 7 months of age are slow to accept introduced cats (Kolb and Nonneman, 1975; Konrad and Bagshaw, 1970).

• Kittens who are isolated from other kittens until late in their first year of life display exaggerated autonomic responses characterized by galvanic skin responses and disruption of regular sleep rhythms (Wenzel, 1959).

• Neonatal isolation leads to changes in normal pain response in dogs (Melzack and Scott, 1957), but it is correlated with increased aggression in cats and rats (Guyot et al., 1983).

• Kittens artificially separated from their mothers at about 2 weeks of age become fearful and aggressive toward both other cats and people, demonstrate random locomotion, and learn poorly (Bacon, 1973; Seitz, 1959).

• Singleton kittens are quicker to emerge from nest boxes, between 3 and 7 weeks (Mendl, 1988), and appear to show little distress when left alone.

• Two kittens, when left by their mother, appear all right while together, but if the kittens are separated and then left by their mother, they appear more distressed than a singleton kitten that is left alone (Mendl, 1988). Most variation in individual behavior is probably not attributable to litter composition (Deag et al., 1988).

• By the time the kittens are about 4 weeks of age, the queen starts to bring them solid food, representing the beginning of the weaning phase (Ewer, 1961; Kovach and Kling, 1967; Martin and Bateson, 1988). This phase is completed by 7 weeks of age.

• Kittens who are nursed on a breeder nipple nurse normally but will not be permitted to nurse on a lactating queen because they give inappropriate social responses to her (Rosenblatt et al., 1961). These kittens can form social attachments to other kittens, but they do so slowly. The extent to which these slow social attachments and inappropriate social responses to lactating queens may affect their own ability to raise kittens has not been investigated. Such scenarios might be an important factor in the abandoned, feral cat population in which a decreased plane of nutrition and early abandonment may be common.

• Kittens who are weaned early also develop predatory behavior far earlier than do normally weaned kittens and are more likely to be mouse killers (Tan and Counsilman, 1985; Warren and Levy, 1979). Late weaning of kittens appears to delay predatory behavior and decreases the propensity to kill mice. This association may be indicative of nonspecific learning in response to the most common prey (mice), but the implications of this are important for people who are going to hand-rear cats. People who hand-raise early-weaned kittens might experience problems with earlier predatory behavior.

• By about 5 to 6 weeks of age, kittens are totally independent in their ability both to eliminate and to start to find substrates resembling the ancestral substrate for elimination.

• Sex differences in social play appear by weeks 12 to 16 but are not present between weeks 4 and 12 (Barrett and Bateson, 1978).

• Females who play with males become more male-like in their play behavior than females who play with females (Caro, 1981a, 1981b). Whether this factor affects later aggressive play behavior for females raised with male siblings only has not been investigated.

• Normal social play starts at approximately 3 to 4 weeks of age when the kitten can ambulate. It is honed when eye-paw coordination is developed at approximately 7 to 8 weeks of age (Barrett and Bateson, 1978; Martin and Bateson, 1985).

• Complex motor activity is fully functional by 10 to 11 weeks (Villablanca and Olmstead, 1979).

• Social play begins to decline at about 12 to 14 weeks of age (Caro, 1981a; West, 1974, 1979).

• Social play patterns become more associated with predatory behavior and social fighting by the third month, possibly concomitant with a change in systems that control motor behavior (Caro, 1980b, 1981b; Pellis et al., 1988; West, 1979).

• Many motor patterns in play resemble motor patterns for hunting (Caro, 1979, 1980a, 1980c), but there is no definitive link with play as “practice” behavior for predatory skills and the development of those skills later in life except to the extent that we all learn from experience in any social situation in which we are placed (Martin, 1984).

• Cats deprived of play still develop predatory behavior (Baerends-van Roon and Baerends, 1979).

• Cats who did not or could not play with small objects as kittens appear to be no different than other cats when examined with regard to predatory skills at 6 months of age (Caro, 1980b), but cats are still more likely to kill the types of prey that they had known since kittenhood (Caro, 1980a).

• The predisposition to respond defensively toward large and difficult prey develops some time during the second month (Adamec et al., 1983).

• Free-ranging domestic cats start to bring their kittens live prey about 4 weeks of age, coincident with the beginning of the weaning.

• Kittens can start to kill mice on their own at approximately 5 weeks of age (Baerends-van Roon and Baerends, 1979).

• It is not inevitable that cats will hunt, especially if they are not weaned early and if they are not taught to do so by their mothers. The presentation of palatable food starting at kittenhood may inhibit hunting, although the behaviors of killing and eating are separately, centrally controlled (Adamec, 1975b, 1976a, 1976b).

• Although individually controlled, there is some interaction between killing and eating, which is substantiated by interactions between areas of the lateral and ventromedial hypothalamus. The ability to inhibit hunting through the presentation of palatable foods early in life and throughout life may be important for clients who do not wish their cats to hunt.

• The tendency to kill when hunting or to exhibit hunting behavior increases with hunger (Biben, 1979) and decreases when prey is more difficult to capture.

• Population control at the community level plays a role in hunting behaviors. Females with kittens to feed tend to be far more adept hunters than females who do not have kittens (Turner and Meister, 1988). It has been postulated that this facilitation is a dopaminergic/prolactin response.

• Weanling kittens eat food preferred by their mother even though that food may not be a common food in cat diets (Wyrwicka, 1978).

• Kittens appear to be able to learn to kill a rat by watching another cat do so (Kuo, 1930). They also learn a preference at this stage and restrict their preference to the strain of rat with which they are familiar.

• Competition within litters may also hone some predatory skills (Caro, 1980a, 1980b, 1980c), and some cats appear to be able to “catch up” to more skilled littermates during ontogeny (Caro, 1980b).

• Cats can learn about a variety of tasks through observation and may learn more quickly if it is their mother they are observing. This finding has profound and helpful applications for clients adopting kittens who may also be able to adopt the mother.

• The tendency for cats to retrieve their young in response to high-pitched vocalization peaks at 1 week after parturition (Schneirla et al., 1963). Early in life (during the first 3 weeks), kittens use ultrasonic calls as they explore their nest (cited in Deag et al., 1988). These calls may function in helping their caretakers locate them and keep them together.

• Eight kitten play postures have been identified (West, 1974):

• Behaviors, some of which are associated with later predatory behavior, that are most successful in eliciting play from another kitten are the pounce (39% of all play-eliciting behaviors), the belly-up display (14% of all play-eliciting behaviors), and the stand-up (16% of all play-eliciting behaviors). These behaviors are 90% effective in obtaining a response from another kitten between 6 and 12 weeks of age.

• As the cat matures, other behaviors become important in the play elicitation communication repertoire. The vertical stance elicits play behavior only 8% of the time at 6 weeks of age, but by 12 weeks of age it elicits play response from another littermate 24% of the time. In contrast, the side-step posture elicits play 20% of the time at 6 weeks of age but only 3% of the time at 12 weeks of age (West, 1979). It is important to emphasize these normal changes in communicatory and play behavior to clients because potential problems in communication could arise when people play too roughly with their kittens. Clients need to know appropriate, age-specific play behaviors.

• In his study of singleton litters, Mendl (1988) found that singleton kittens did not engage more frequently in self-play or object play than kittens in litters of two. This finding suggests that social and object play should be separately driven.

• Between 2 and 4 weeks of age, the particular closeness experienced by kittens to other kittens has a calming effect (Rosenblatt et al., 1962).

• Physical contact with the queen, particularly nuzzling of the face, has a calming effect on kittens (Beaver, 1992). These observations have implications for early weaning.

• Kittens are weaned early if the queen cannot provide enough food; this results in stimulation of the early development of both object and social play (Bateson et al., 1990).

• In the case of early weaning, the siblings and the mother are still present; their presence could have a significant effect on the extent to which rough play might be modulated. In the usual, non-experimental situation involving early weaning, the mother is no longer present. No studies have been done on whether these two types of early weaning have different effects on inappropriate play behavior or the early development of predatory aggression in cats. It is likely that early weaning that also precludes the social interaction of an older, experienced cat could foster more inappropriate play behavior and play aggression.

• Feral cats often abandon kittens by about 4 months of age. At this time, the kittens increase their environmental exploration.

• Barrett and Bateson (1978) noted that males engage in twice the object play as females by 7 weeks of age, and by 19 weeks of age these free-ranging males are demonstrating sexual behavior.

• Female kittens usually do not demonstrate sexual behavior until 23 weeks of age. Litters composed solely of females appear to be less aggressive in their play than all-male litters; this difference is recognizable by weeks 12 to 16.

• West (1979) postulated that the function of play, rather than teaching cats to be better predators later in life, might be to keep litters together when the litter is vulnerable; this would enhance their ability to develop good social relationships that might serve to redress vulnerability later in life. No studies have directly addressed this issue, but the work of Macdonald et al. (1987) suggests that this might be so.

• Kittens that were handled by people for only 15 minutes a day from birth through 12 to 14 weeks of age spent more time exploring the person and giving head rubs and would leave and return several times.

• Kittens in home-reared litters that were held 1 to 2 hours a day, if brought to the laboratory, would go directly to people and climb onto their lap, purr, and go to sleep. These behaviors were not seen in the laboratory kittens, although laboratory kittens were not fearful of people. The home-reared kittens were handled four to eight times longer than the laboratory kittens, but they were also exposed to a more varied and unpredictable environment than the laboratory kittens.

• It would be inappropriate to over-interpret these results, but it is probably fair to say that the earlier the kittens are handled and the more they are handled, the more friendly they are likely to be.