Article

Dog Pups’ Attractiveness to Humans Peaks at Weaning Age

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Abstract

The domestic dog (Canis lupus familiaris) is characterized by greatly reduced parenting investment compared with the wild type wolf (C. l. lupus) from which it is descended. Unlike wolf pups, which are reared by both parents into their second year of life, dog pups are abandoned by their mother at weaning around eight weeks of age. This relatively small parental involvement may contribute to the high pup mortality observed in dogs not living as pets. We hypothesized that people would find dog pups most attractive around weaning age when conspecific parental care is significantly reduced and pup mortality rate is high. Younger and older pups would benefit less from human intervention because in the former case the mother is providing care, and in the latter their survival is already compromised. To test this hypothesis, 51 participants rated the attractiveness of 39 black and white headshot photographs presented on a computer screen of dog pups from three breeds (Jack Russell Terrier, Cane Corso, and White Shepherd), from birth to 7 months old. In line with our hypothesis, attractiveness of Cane Corsos peaked at 6.3 weeks of age; Jack Russell Terriers’ attractiveness peaked at 7.7 weeks; and White Shepherds were most attractive at 8.3 weeks. There were also differences in attractiveness between the breeds, with Cane Corsos rated less attractive than the other two breeds. If this attractiveness motivates humans to care for the dog pups and thereby improves pup survival, this could confer significant advantages to dogs, and may contribute to our understanding of the process of domestication.

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... enlarging the eyes or foreheadcan magnify these effects (e.g. Archer & Monton 2011; Lehmann et al. 2013;Chersini et al. 2018). There is also evidence that similar processes persist in generating both human-and animal-focused 'kindchenschema' effects (Golle et al. 2013). ...
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Article
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... This is important, as many cats that are up for adoption are still kittens. The baby schema, the evolutionary mechanism that draws the attention and compassion of human caretakers to human infants (Glocker, Langleben, Ruparel, Loughead, Gur, & Sachser, 2009) also extends to infant animals (Chersini, Hall, & Wynne, 2018;Golle, Lisibach, Mast, & Lobmaier, 2013). There is some evidence that kittens are adopted more readily than adult cats (Weiss, Miller, Mohan-Gibbons, & Vela, 2012;Workman & Hoffman, 2015). ...
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Physical traits that are characteristic of human infants are referred to as baby‐schema, and the notion that these affect perception of cuteness and elicit care giving from adults has a long history. In this study, infant‐similarity was experimentally manipulated using the difference between adult and infant faces. Human infant, human adult and cat faces were manipulated to look more (human) infant‐like or adult‐like. The results from the current study demonstrate the impact of infant‐similarity on human adults' perception of cuteness across the three different types of face. The type of face had a large impact on perceived cuteness in line with the expected infant‐similarity of the images. Infants and cats were cutest while adults were less cute. The manipulations of infant‐similarity, however, had similar effects on the perception of cuteness across all three types of face. Faces manipulated to have infant‐like traits were rated as cuter than their equivalents manipulated to have adult‐like traits. These data demonstrate that baby‐like traits have a powerful hold over human perceptions and that these effects are not simply limited to infant faces.
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Six bitches and their offspring were observed in the natural environment to study the early ontogeny of certain processes like eye opening, nipple preference, play, sexual activities and locomotion. Thirteen puppies out of 35 survived at the age of 3 months indicating 63% mortality. Eye slits were observed on day 12 (median) of life, and the eyes completely opened on 17 day (median) of life. The rearmost (fourth) nipple pair presumably containing more milk was suckled preferably by the puppies showing no sex bias. Social communication among the littermates was developed through playful interactions. Play behaviour developed in three subsequent stages—social play, agonistic play, and pseudo-sexual activity; at 3, 5 and 6 weeks, respectively. Playful interactions increased with the age of the puppies to establish a stable social hierarchy, and suddenly decreased between 8 and 10 weeks of life. Aggressive play tended to be initiated by males and specific individuals within a litter, suggesting individual variation in aggressiveness. Development of pseudo-sexual behaviour especially in male puppies by week 6 was an interesting feature of this study. The puppies were mobile at the age of week 3 when the eyes completely opened, and they were highly mobile when the suckling bouts disappeared and they traveled independently for food collection (10–11 weeks of life).
Article
Seventeen litters of German Shepherd dogs were observed for 5–7 days per week between 3 and 8 weeks post-partum. Social behaviour patterns, aggressive signals towards the puppies and nursing were quantified. Mothers were found to differ in the frequency of both social and aggressive behaviour. Nursing declined during the period, while both agonistic and grooming behaviour towards puppies increased until the 7th week. During Week 7, agonistic behaviour patterns were found to be significantly correlated to grooming behaviour patterns. Some of these behaviour traits were significantly correlated to the puppies performance on a puppy test given at the age of 8 weeks. It is suggested that the interaction between mother and offspring may facilitate the appearance of submission, and the effects on later trainability are discussed.
Article
A variety of approaches have been used to understand the evolution of male parental care. General frameworks are provided by Trivers’ theory of sexual selection (1972), the theory of life history strategies (see Horn, 1978; Stearns, 1976) and game theory (Grafen and Sibly, 1978; Maynard Smith, 1977). The factors invoked to explain male parental investment have varied with the level of analysis; intrinsic biological factors such as internal versus external fertilization (Dawkins and Carlisle, 1976; Ridley, 1978) or the capacity to invest (Orians, 1969) have been used to illuminate differences between large taxonomic units such as the vertebrate classes; ecological factors such as harshness (Wilson, 1975), richness (Jenni, 1974), and unpredictability (Pitelka et al., 1974) have all been invoked to explain the presence of unusual levels of male investment in smaller taxonomic units.
Article
In the current resurgence of interest in the biological basis of animal behavior and social organization, the ideas and questions pursued by Charles Darwin remain fresh and insightful. This is especially true of The Descent of Man and Selection in Relation to Sex, Darwin's second most important work. This edition is a facsimile reprint of the first printing of the first edition (1871), not previously available in paperback. The work is divided into two parts. Part One marshals behavioral and morphological evidence to argue that humans evolved from other animals. Darwin shoes that human mental and emotional capacities, far from making human beings unique, are evidence of an animal origin and evolutionary development. Part Two is an extended discussion of the differences between the sexes of many species and how they arose as a result of selection. Here Darwin lays the foundation for much contemporary research by arguing that many characteristics of animals have evolved not in response to the selective pressures exerted by their physical and biological environment, but rather to confer an advantage in sexual competition. These two themes are drawn together in two final chapters on the role of sexual selection in humans. In their Introduction, Professors Bonner and May discuss the place of The Descent in its own time and relation to current work in biology and other disciplines.
Article
Hinde & Barden (1985, Anim. Behav., 33, 1371–1373) suggested that the teddy bear has evolved to match sign stimuli that release nurturant behaviour. Bears are usually bought for infants and young children. From an evolutionary perspective it seems paradoxical that young children who themselves require intensive nurture should exhibit a preference for objects that afford nurturing. The purpose of this study was to investigate the origin of the preference for nurturant sign stimuli. The preference for baby-featured bears was examined in three age groups: 4, 6 and 8 year olds. The 6 and 8 year olds significantly preferred baby-featured bears: however, the 4 year olds did not. The evolution of the teddy bear is thus apparently not driven by the ostensible consumer, the young child; the preference for baby features may be part of a wider, relatively late development of nurturant feelings towards young.
Article
Parental care in free-ranging dogs was investigated in Katwa town, India. Six lactating bitches, 4 were monogamous. The gestation period varied from 62 to 65 days. Mean (±S.D.) litter size of 5.83 (±1.57) with a sex ratio of 1.69:1 in favour of male was recorded in this study. High mortality (63%) of pups occurred by the age of 3 months. Mothers were in contact with the litters for 13 weeks of the litters’ life. There was a negative correlation between the duration of mother–litter contact in any observation session and the age of the pups. Milk feeding by the mothers was continued for 10–11 weeks of the litters’ life. The duration of milk feeding in any 30-min observation session reached a maximum of 27.54min during the 1st week and a minimum of 2.22min during the 11th week of the litters’ life. All the mothers in this study were observed to feed the pups by regurgitation. For the first 2 weeks immediately after parturition, the lactating females were observed to be more aggressive to protect the pups. The four males (male parents) were in contact with the litters as ‘guard’ dogs for the first 6–8 weeks of litters’ life. In absence of the mothers, they were observed to prevent the approach of strangers by vocalizations or even by physical attacks. Moreover, one male fed the litter by regurgitation showing the existence of paternal care in free-roaming domestic dogs.
Article
Several studies indicate that the weaning process is affected by costs and benefits linked with getting milk or solid food for the young. It has even been proposed that optimal weaning time would vary within litters and that it may be possible to identify different weaning strategies for the young. In the present study the within-litter and between-litter variations in milk and solid food intake in domestic dog pups were described, and possible existence of different weaning strategies of pups was examined. Four litters of the breed Swedish Dachsbracken and their mothers were observed during Weeks 2–7 post partum, by manual observations. All pups were weighed regularly in connection with suckling and eating solid food and measurements of amount of milk ingested per pup and suckling and of solid food intake per pup and meal were made. The variations in milk intake and solid food intake were high throughout the period. In general, the correlations between milk intake and solid food intake were small but negative. Pups with a higher intake of solids tended to weigh more at Day 49 and had a significantly larger weight gain between Days 21 and 49. In total, there seemed to exist a certain compensation between milk and solid food intake, but it was not obvious within litters. No direct support was found for the theory of weaning strategies, but there was a trend that pups getting more milk were also more active towards the mother. Furthermore, there was a highly significant consistency between solid food intake and weight of the pups and in solid food intake between weeks throughout the period. This could be an indication that weaning strategies exist, even though the importance of the psychological satisfaction of suckling itself in such a complicated process as weaning should not be underestimated in social animals like the dog.
Article
The aim of the present study was to increase adoption rates of dogs housed in shelters. Previous research suggests that the public perceives friendly and sociable dogs as more adoptable. The present study hypothesized that dogs trained to gaze into potential adopters’ eyes would be perceived as more attractive and would therefore have a greater likelihood of being adopted. In addition, we investigated other individual factors that may predict adoption success. For each dog in the study, we tracked outcome (adoption or euthanasia), physical characteristics, and how they were acquired by the shelter. Dogs in a group trained to gaze at people were not significantly more likely to be adopted than untrained dogs in a control group (70.7% in the training group vs. 67.8% in the control group, P>0.10). However, breed type, mode of intake (how dogs were taken into the shelter), and kennel location were predictive of adoption (P<0.001, P<0.05. and P<0.05 respectively) and size, breed type, and mode of intake were predictive of length of stay (P<0.05, P=0.05, and P<0.01 respectively). In a second experiment, participants unaware of the dogs’ outcomes (adoption or euthanasia) rated photographs of the dogs, according to attractiveness, on a scale ranging from 0 to 1. The average rating of attractiveness for the adopted and euthanized group were significantly different: 0.50 (SD=0.08) for adopted dogs and 0.46 (SD=0.09) for the euthanized dogs (P<0.05). These findings suggest that other factors besides gazing may be more important to adopters when considering adoption of a dog.
Article
Approaches by human passers-by to a Golden Retriever puppy with a human companion were tallied as the puppy aged from ten weeks to 33 weeks. Over this period, approaches were most numerous when the puppy was youngest, with females approaching more than males during the first half of sampling, but equaling male approaches during the second half. Both the number of human approaches and the proportions of males and females were independent of the sex of the puppy's human companion. The results suggest a human, and especially a female, preference for canine juvenescence.
Article
Every year sees an increase in the number of dogs admitted to rescue shelters. However well these dogs are cared for in the shelter it cannot be ignored that being in such a situation is stressful and the time spent in the shelter may change the dogs' behaviour which may in turn influence their chances of being bought from the shelter. This research examined the behaviour of stray and unwanted dogs on their first, third and fifth days in an Ulster Society for the Prevention of Cruelty to Animals (USPCA) shelter. A questionnaire was also distributed to members of the public to determine how popular the USPCA was as a place from where to purchase a dog, and what factors about a dog's physical characteristics, behaviour and environment influenced potential buyers. Results revealed no significant difference between the behaviour of stray and unwanted dogs although the public viewed stray dogs as much less desirable than unwanted dogs. Time in the shelter had no adverse effects on the dogs' behaviour. Indeed those changes which did occur during captivity, dogs being more relaxed in the presence of people and eating food more quickly, may be considered as positive changes. The USPCA was viewed as a popular place from which to buy a dog. Off actors influencing the public's choice, the dog's environment and behaviour appeared more important than its physical characteristics. The presence of a toy in the dog's cage greatly increased the public's preference for the dog, although the toy was ignored by the dog. The welfare implications of sheltering dogs are discussed
Article
We compare differences in the reproductive strategies of "free-living" dogs with their wild relatives in the genus Canis, of which the dog is a very recently evolved member. The members of this genus display a greater range of parental motor patterns than generally seen in other species of Carnivora, including pair-bonding and extended parental care; parents regurgitate to offspring and provision them with food for months to as long as a year. But the domestic dog does not routinely display these genus-typical behaviors. While this has generally been assumed to be a result of direct human intervention, humans have little reproductive control over the vast majority of domestic dogs. We analyze the low frequency of display of genus-typical behaviors and postulate that the dog's reproductive behaviors are an adaptation to permanent human settlement and the waste resources associated with it. Adaptation to this environment has decreased seasonality, increased the fecundity of unrestrained dogs and reduced the need for prolonged parental care. The consequences of greater fecundity and reduced parental care are compared to the reproductive behavior of other species of the genus.
Article
Discusses the role of selection based on particular human propensities in the evolution of artifacts. Changes in teddy bear appearance since 1903 are related to K. Lorenz's (1950) suggestion that certain key features elicit nurturance and affection and that dolls and cartoon characters are influenced by this dynamic. (5 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The writer first discusses the innate and endogenous factors in instinctive responses of animals, pointing out that the various external signals which release the responses summate in their effect in a non-Gestalt manner. In both domesticated animals and civilized man, the complex of stimuli capable of releasing instinctive behavior expands, decreasing the precision of the instinct and diminishing the ability to survive in the natural environment. And so the development of reason (contrasted with instinct) is both an advance and a decadence, an advantage and a danger. Only by purposeful exercise of this reason itself, and by voluntarily limiting his liberty, can man make up for his loss of guiding instincts and become master of his destiny. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Article
A set of infant features (large forehead, large and low-lying eyes, and bulging cheeks), were described in classical ethology as social releasers, simple stimuli that evoke a stereotyped response, in this case nurturing. We assessed the attractiveness of such features in the faces of dogs or cats (adults and young) or teddy bears or human infants, and also related these preferences to the degree of attachment to a pet. Overall, faces with the infant features were rated as more attractive than those without. Human infant faces were no more attractive than those of kittens or puppies. Pet faces were rated as more attractive by pet owners than non-pet owners, regardless of whether the faces had infant features. A preference was also found for infant features in teddy bear faces. Women showed higher ratings than men for pets with infant features, but not for human infants or pets without infant features. Parents found human infants’ faces more attractive than did non-parents, but there were no differences for other faces with infant features. Preferences were to some extent specific to the participant’s preferred pet species. Owners who were more strongly attached to their pets showed stronger preferences for photographs with infant features. The findings are discussed in terms of the concept of social releaser, and its part in the development of attachment to a pet species.
Article
Weaning and signs of a parent-offspring conflict were studied in four females of the Swedish Dachsbracken breed of domestic dog and their pups. The animals were observed from the second to the seventh week of age of the pups. In addition to regular weighing, measurements of milk and solid food intake per pup and meal were also made, and samples of milk from the mothers were collected and analysed. The most important mechanism for weaning seemed to be on the behavioural level. The time that the mother spent with her pups decreased continuously from week 2 to week 7, as did the number of sucklings per hour. Furthermore, both duration of suckling and the number of sucklings initiated by the mother decreased during the period, while the proportion of sucklings where the mother was standing increased steadily. The weights of mothers stayed rather constant during the period and there was no difference in the amount of milk given per suckling or in the composition of milk between the early and late weeks of lactation. Consequently, costs for the mother, in terms of loss of weight, were negligible as she was able to compensate for the increased energy demand of lactation with an increased food intake. There was a tendency for care-giving behaviour to decrease and aggression from the mother to increase at the same time as there was a tendency for care-seeking and contact-seeking behaviour from the pups to increase. These changes, together with the less frequent initiation of suckling by the mother, could perhaps be seen as signs of conflict. Conflict was defined according to TRIVERS' theory (1974) and referred to the disagreement between the female and her pups about the amount of care given. However, although the animals were kept in a way that allowed them to perform as much as possible of their natural behaviour, the good nutritional conditions, one of the characteristics of captive life, may have reduced overt parent-offspring conflict.
Article
Reproductive behaviour of free-ranging dogsCanis familiaris Linnaeus, 1758 was studied in a village in the state of West Bengal, India. Increased synchronized breeding was the most striking feature of this study. October (late monsoon) represented the peak period of mating for the feral dogs. Of all courting males, only 41% were observed to mount and copulate. On average, each male mounted 5.47 ± 2.49 (mean ± SD) times per hour. Of all mountings, only 10% were successful matings, ie copulatory ties. There was a negative correlation between the number of courting males and the number of successful copulations. The average duration of copulatory tie was 15.73 ± 7.75 min. Several factors interrupting the duration of copulatory ties were identified. December was the peak period of pup rearing. Mean litter size was 5.70 ± 2.03 with a male-biased sex ratio 1.41:1. Only a single annual breeding cycle recorded here differed from the previous studies on European and American dogs. Mothers spent most of the time with their pups at the dens during the early stage of rearing. The duration of time spent at dens by mothers was minimum when the pups were highly mobile at the age of 10 weeks. The lactating mothers were observed to be more aggressive immediately following litter production. Typically, an old adult male remained near the den as a ‘guard’. Key words Canis familiaris -sexual behaviour-copulatory tie-breeding
Article
The widely accepted viewpoint that feralization is the reverse of domestication requires that the feralization process be restricted to populations of animals and, therefore, cannot occur in individuals. An alternative, ontogenetic approach is presented in which feralization is defined as the process by which individual domestic animals either become desocialized from humans, or never become socialized, and thus behave as untamed, non-domestic animals. Feralization will vary among species and, intraspecifically, will depend upon an individual's age and history of socialization to humans. Because feralization is not equated with morphological change resulting from evolutionary processes, species formation is not an accurate indicator of feral condition.
Article
Ethologist Konrad Lorenz proposed that baby schema ('Kindchenschema') is a set of infantile physical features such as the large head, round face and big eyes that is perceived as cute and motivates caretaking behavior in other individuals, with the evolutionary function of enhancing offspring survival. Previous work on this fundamental concept was restricted to schematic baby representations or correlative approaches. Here, we experimentally tested the effects of baby schema on the perception of cuteness and the motivation for caretaking using photographs of infant faces. Employing quantitative techniques, we parametrically manipulated the baby schema content to produce infant faces with high (e.g. round face and high forehead), and low (e. g. narrow face and low forehead) baby schema features that retained all the characteristics of a photographic portrait. Undergraduate students (n = 122) rated these infants' cuteness and their motivation to take care of them. The high baby schema infants were rated as more cute and elicited stronger motivation for caretaking than the unmanipulated and the low baby schema infants. This is the first experimental proof of the baby schema effects in actual infant faces. Our findings indicate that the baby schema response is a critical function of human social cognition that may be the basis of caregiving and have implications for infant-caretaker interactions.
Article
This study examined adults' evaluations of likeability and attractiveness of children's faces from infancy to early childhood. We tested whether Lorenz's baby schema hypothesis (Zeitschrift für Tierpsychologie (1943), Vol. 5, pp. 235-409) is applicable not only to infant faces but also to faces of children at older ages. Adult participants were asked to evaluate children's faces from early infancy to 6 years of age in terms of their likeability and attractiveness, and these judgments were compared with those of adult faces. It was revealed that adults judged faces of younger children as more likeable and attractive than faces of older children, which were in turn judged as more likeable and attractive than adult faces. However, after approximately 4.5 years of age, the baby schema no longer affected adults' judgments of children's facial likeability and attractiveness. These findings suggest that the baby schema affects adults' judgments of not only infant faces but also young children's faces. This influence beyond infancy is likely due to the fact that facial cranial growth is gradual during early childhood and certain crucial infantile facial cues remain readily available during this period. Future studies need to identify these specific cues to better understand why adults generally show positive responses to infantile faces and how such positive responses influence the establishment and maintenance of social relationships between young children and adults.
Article
Biologists, breeders and trainers, and champion sled dog racers, Raymond and Lorna Coppinger have more than four decades of experience with literally thousands of dogs. Offering a scientifically informed perspective on canines and their relations with humans, the Coppingers take a close look at eight different types of dogs—household, village, livestock guarding, herding, sled-pulling, pointing, retrieving, and hound. They argue that dogs did not evolve directly from wolves, nor were they trained by early humans; instead they domesticated themselves to exploit a new ecological niche: Mesolithic village dumps. Tracing the evolution of today's breeds from these village dogs, the Coppingers show how characteristic shapes and behaviors—from pointing and baying to the sleek shapes of running dogs—arise from both genetic heritage and the environments in which pups are raised. For both dogs and humans to get the most out of each other, we need to understand and adapt to the biological needs and dispositions of our canine companions, just as they have to ours.
An adaptationist programme has dominated evolutionary thought in England and the United States during the past 40 years. It is based on faith in the power of natural selection as an optimizing agent. It proceeds by breaking an oragnism into unitary 'traits' and proposing an adaptive story for each considered separately. Trade-offs among competing selective demands exert the only brake upon perfection; non-optimality is thereby rendered as a result of adaptation as well. We criticize this approach and attempt to reassert a competing notion (long popular in continental Europe) that organisms must be analysed as integrated wholes, with Baupläne so constrained by phyletic heritage, pathways of development and general architecture that the constraints themselves become more interesting and more important in delimiting pathways of change than the selective force that may mediate change when it occurs. We fault the adaptationist programme for its failure to distinguish current utility from reasons for origin (male tyrannosaurs may have used their diminutive front legs to titillate female partners, but this will not explain why they got so small); for its unwillingness to consider alternatives to adaptive stories; for its reliance upon plausibility alone as a criterion for accepting speculative tales; and for its failure to consider adequately such competing themes as random fixation of alleles, production of non-adaptive structures by developmental correlation with selected features (allometry, pleiotropy, material compensation, mechanically forced correlation), the separability of adaptation and selection, multiple adaptive peaks, and current utility as an epiphenomenon of non-adaptive structures. We support Darwin's own pluralistic approach to identifying the agents of evolutionary change.
Article
To determine whether certain characteristics of dogs offered for adoption are associated with successful adoption. Retrospective cohort study. 1,468 relinquished dogs offered for adoption at a local humane society. Data regarding dogs offered for adoption were obtained from surveys completed by previous owners. Data were analyzed by use of bivariate statistics and multivariable logistic regression. Of dogs offered for adoption, 1,073 were successfully adopted, 239 were not adopted, and 157 were returned to the shelter after adoption. Terrier, hound, toy, and nonsporting breeds were found to be significantly associated with successful adoption (P < 0.05, chi 2 analysis). Certain coat colors (gold, gray, and white), small size, and history of an indoor environment were also significant predictors of successful adoption. The correlation coefficient (0.048) indicated that only a small percentage of variance in adoption success could be explained by the multiple logistic regression model. Animal shelter managers with limited kennel capacity may wish to periodically use surveys to determine whether the type of dog being offered to the public reflects the type of dog the public will adopt.
Article
This study reports the findings from street interviews on owned dogs (N = 442) in New Providence, The Bahamas. Many households kept dogs outside, and roughly 43% of households allowed at least 1 dog to roam. Dogs kept inside most likely were considered a companion, whereas dogs used for security were kept outside. With 36.1% of the dog population neutered and 4.4 puppies per litter surviving to breeding age (6 months), the population continues to produce more dogs than are required just to maintain its numbers. Potcakes, the local mongrel, followed by pit bulls, were the most commonly kept dogs. Comparison with a study conducted in the Yucatan, Mexico (A. Ortega-Pacheco et al., 2005), suggests that the hostile subtropical environment of New Providence well may be responsible for checking the growth of the dog population. The study also suggests that until less than 20% of the females breed, there will continue to be a dog problem on the island.
boot: Bootstrap R (S-Plus) Functions. R package version 1.3-11
  • A Canty
  • B Ripley
Canty, A., & Ripley, B. (2014). boot: Bootstrap R (S-Plus) Functions. R package version 1.3-11. https://CRAN.Rproject.org/package=boot.
  • Zeitschrift Für Tierpsychologie
Zeitschrift für Tierpsychologie, 5, 235-409. doi:10.1111/j.1439-0310.1943.tb00655.x.