Karen L Bales
Biographic Data
| ID | 5788565 |
|---|---|
| NAME | Karen L Bales |
| GIVEN NAMES | Karen L |
| FAMILY NAME | Bales |
| SIGNATURE | BALES K L |
| AFFILIATIONS | University of California, Davis |
| ORCID | 0000-0001-5826-2095 |
| VERIFIED | Yes |
| TOTAL WORKS | 32 |
| TOTAL CITATIONS | 2 |
| WORKS AS AUTHOR | 32 |
| WORKS AS EDITOR | 0 |
| FIRST PUBLICATION YEAR | 2001 |
| LATEST PUBLICATION YEAR | 2026 |
| H-INDEX | 1 |
Inferring the Demographic History of Coppery Titi Monkeys ( Plecturocebus cupreus ) From High‐Quality, Whole‐Genome, Population‐Level Data
Despite being an important biomedical model species for social behavior, the natural population history of the coppery titi monkey ( Plecturocebus cupreus ) remains largely uncharacterized, in part due to the scarcity of genomic resources available for the species. Apart from the inherent interest in the demographic dynamics of this abundant platyrrhine native to the Amazon forest of Brazil and Peru, this quantification will also serve as a centr…
Plants as Enrichment? The Effect of Live Plants on the Behavior and Welfare of Indoor‐Housed Titi Monkeys ( Plecturocebus cupreus )
The biophilia hypothesis states that humans have an innate tendency to enjoy the presence of greenery due to vegetative‐rich areas serving as adaptive environments during our evolutionary history. It is possible that other extant primate species may show a similar response to the presence of plants, but direct experimental interventions on indoor‐housed primates, with plants isolated as a variable, represent a gap in the literature. In this study…
Survival rates and mortality risks of Plecturocebus cupreus at the California National Primate Research Center
This article describes survivorship and explores factors affecting mortality risks in a captive colony of coppery titi monkeys ( Plecturocebus cupreus ) housed at the California National Primate Research Center (CNPRC), at UC Davis, in Davis, CA. We analyzed data collected on individuals since the colony's creation in the 1960s, with a sample of 600 animals with partially complete information (date of birth, age at death, body mass, parental line…
Initial compatibility during a “Speed‐Dating” test predicts postpairing affiliation in titi monkeys ( Plecturocebus cupreus )
Behavioral compatibility plays a critical role in shaping how potential mates interact with and evaluate each other and whether they choose to pursue a relationship. Compatibility is especially important for mate choice and relationship quality in pair‐bonding species that form long‐term attachments between mates. Although this process has been studied in humans and birds, relatively few studies have investigated it in non‐human primates. In this…
Parenting costs time
Relationships support social animals' health, but maintaining relationships is challenging. When transitioning to parenthood, new parents balance pair-bond maintenance with infant care. We studied pair-bond maintenance via affiliation in 22 adult titi monkey pairs (Plecturocebus cupreus) for 16 months centered around their first offspring's birth. Pair affiliation peaked during pregnancy, decreased across the postpartum period, and rose after rea…
Psychobiological development in primates
Relationship tenure differentially influences pair‐bond behavior in male and female socially monogamous titi monkeys ( Callicebus cupreus )
Pair‐bonded primates have uniquely enduring relationships and partners engage in a suite of behaviors to maintain these close bonds. In titi monkeys, pair bond formation has been extensively studied, but changes across relationship tenure remain unstudied. We evaluated differences in behavioral indicators of pair bonding in newly formed (~6 months paired, n = 9) compared to well‐established pairs (average 3 years paired, n = 8) of titi monkeys ( …
Coppery titi monkey ( Plecturocebus cupreus ) pairs display coordinated behaviors in response to a simulated intruder
Mate guarding and coordinated behaviors between partners are important for the maintenance of monogamous pair bonds. To study the effects of a perceived unfamiliar social intruder on females' behavior, we used coppery titi monkeys ( Plecturocebus cupreus ). We examined the effects of male aggressive temperament on females' behavior and the effects of each behavior performed by the male on the same female behavior. Using a mirror, we simulated a s…
Introduction to special section on Covid‐19 in primatology
The entire world is currently grappling with the implications of COVID-19 on our health, economies, personal lives, and futures. As primatologists, we are also experiencing the effects on our research and our careers. Many of us are considering how we and our students can return to doing our research, while acting responsibly toward our nonhuman primate research subjects, as well as the human communities that live in the same geographical regions…
Individuality in the vocalizations of infant and adult coppery titi monkeys ( Plecturocebus cupreus )
As social animals, many primates use acoustic communication to maintain relationships. Vocal individuality has been documented in a diverse range of primate species and call types, many of which have presumably different functions. Auditory recognition of one's neighbors may confer a selective advantage if identifying conspecifics decreases the need to participate in costly territorial behaviors. Alternatively, vocal individuality may be nonadapt…
Effect of reward type on object discrimination learning in socially monogamous coppery titi monkeys ( Callicebus cupreus )
Highly valued food items are often used as rewards to reinforce an animal's behavior. For social species, social interaction is rewarding and can drive an individual's behavior as well. In the currently study, we wanted to compare the efficacy of a food reward and a social reward on object discrimination learning in socially monogamous titi monkeys. We hypothesized that titi monkeys would perform more accurately for a social reward (their pair ma…
Effects of aggressive temperament on endogenous oxytocin levels in adult titi monkeys
Coordination of oxytocin (OT) activity and partner interactions is important for the facilitation and maintenance of monogamous pair bonds. We used coppery titi monkeys (Callicebus cupreus) to identify the effects of male aggressive temperament on OT activity, affiliative partner-directed behaviors, aggressive partner-directed behaviors, anxiety-related behaviors, and hormone-behavior interactions. We used a mirror technique, simulating an intrud…
Oxytocin, vasopressin, and primate behavior
It has become increasingly clear that the nonapeptide hormones oxytocin and vasopressin have more diverse behavioral and physiological effects across species and across individuals than was initially recognized. To reflect this variation, we would like to introduce our Special Issue, entitled Oxytocin and Vasopressin in Primate Behavior, by celebrating the diversity that is found across the articles within it. While every article directly address…
American Journal of Primatology
Effects of pair bonding on dopamine D1 receptors in monogamous male titi monkeys ( Callicebus cupreus )
Pair bonding leads to increases in dopamine D1 receptor (D1R) binding in the nucleus accumbens of monogamous prairie voles. In the current study, we hypothesized that there is similar up‐regulation of D1R in a monogamous primate, the titi monkey ( Callicebus cupreus ). Receptor binding of the D1R antagonist [ 11 C]‐SCH23390 was measured in male titi monkeys using PET scans before and after pairing with a female. We found that within‐subject analy…
Infant titi monkey behavior in the open field test and the effect of early adversity
The open field test is commonly used to measure anxiety-related behavior and exploration in rodents. Here, we used it as a standardized novel environment in which to evaluate the behavioral response of infant titi monkeys (Callicebus cupreus), to determine the effect of presence of individual family members, and to assess how adverse early experience alters infant behavior. Infants were tested in the open field for 5 days at ages 4 and 6 months i…
Pair-Bonding in Other Mammals
Pair-bonding is a behavioral construct central to adult human relationships and is also displayed in some other mammalian species (primarily ones which display monogamy as a social system). These other mammal species have given us the opportunity both to refine our definition of pair-bonding and to investigate its neurobiological substrates.
Alternative Models for Small Samples in Psychological Research
Unavoidable sample size issues beset psychological research that involves scarce populations or costly laboratory procedures. When incorporating longitudinal designs these samples are further reduced by traditional modeling techniques, which perform listwise deletion for any instance of missing data. Moreover, these techniques are limited in their capacity to accommodate alternative correlation structures that are common in repeated measures stud…
Laboratory simulations of mate‐guarding as a component of the pair‐bond in male titi monkeys, Callicebus cupreus
Mate-guarding and territorial aggression (both intra- and inter-sexual) are behavioral components of social monogamy seen in male coppery titi monkeys (Callicebus cupreus) both in the field and in the laboratory. Methodology for studying these behaviors in captivity facilitates the translation of questions between field and laboratory. In this study, we tested whether exposure to a mirror would stimulate mate-guarding behavior in male titi monkey…
Development of a partner preference test that differentiates between established pair bonds and other relationships in socially monogamous titi monkeys ( Callicebus cupreus )
Partner preference, or the selective social preference for a pair mate, is a key behavioral indicator of social monogamy. Standardized partner preference testing has been used extensively in rodents but a single test has not been standardized for primates. The goal of this study was to develop a partner preference test with socially monogamous titi monkeys (Callicebus cupreus) adapted from the widely used rodent test. In Experiment 1, we evaluate…
“Monogamy” in Primates
This paper is the introduction to a special issue on "'Monogamy' in Primates: Variability, Trends, and Synthesis." The term "monogamy" has undergone redefinition over the years, and is now generally understood to refer to certain social characteristics rather than to genetic monogamy. However, even the term "social monogamy" is used loosely to refer to species which exhibit a spectrum of social structures, mating patterns, and breeding systems. P…
Population genetics of the California National Primate Research Center’s (CNPRC) captive Callicebus cupreus colony
Why primate models matter
Research involving nonhuman primates (NHPs) has played a vital role in many of the medical and scientific advances of the past century. NHPs are used because of their similarity to humans in physiology, neuroanatomy, reproduction, development, cognition, and social complexity-yet it is these very similarities that make the use of NHPs in biomedical research a considered decision. As primate researchers, we feel an obligation and responsibility to…
Differences in Titi Monkey ( Callicebus cupreus ) Social Bonds Affect Arousal, Affiliation, and Response to Reward
Titi monkeys ( Callicebus cupreus ) are a monogamous, New World primate. Adult pair‐mates form a bidirectional social bond and offspring form a selective unidirectional bond to their father. Some of the neurobiology involved in social bonds and maternal behavior is similar to the neural circuitry involved in nonsocial reward. Due to these overlapping mechanisms, social states may affect responses to external rewarding stimuli. We sought to determ…
Hormonal and Experiential Predictors of Infant Survivorship and Maternal Behavior in a Monogamous Primate ( C allicebus cupreus )
To better understand the roles that hormones and experience play in infant survival and maternal behavior in a biparental primate species, we analyzed urinary estrone ( E 1 C ) and pregnanediol glucuronide ( PdG ) from 24 socially housed titi monkey ( C allicebus cupreus) females over 54 pregnancies ( N = 1,430 samples). Pregnancies were categorized according to whether the infant survived ( N = 35) or not ( N = 19), and by maternal parity (primi…
Sources of variability in numbers of live births in wild golden lion tamarins ( Leontopithecus rosalia )
We examined the effects of several variables on the number of live births in multiparous females in a wild population of golden lion tamarins ( Leontopithecus rosalia ). Independent variables included the number of infants born to a female the previous breeding season, the number of infants weaned the previous breeding season, the female’s age and body mass, the number of adult males and helpers in the group, and the inbreeding coefficient of the…
Endocrine Monitoring of Wild Dominant and Subordinate Female Leontopithecus rosalia
Program and Conference Schedule
Relations among birth condition, maternal condition, and postnatal growth in captive common marmoset monkeys ( Callithrix jacchus )
The present study characterizes the relations among maternal condition, litter size, birth condition, and growth in body weight for a population of common marmosets. The subjects of the study were marmosets born into a single colony between 1994 and 2001. Three sets of analyses were conducted to answer the following questions: 1) Is there a relationship between litter size, maternal condition, and birth condition? In the study population, materna…
Social and reproductive factors affecting cortisol levels in wild female golden lion tamarins ( Leontopithecus rosalia )
The steroid hormone cortisol has been associated with different levels of “stress” as well as different reproductive conditions in many primates. In callitrichids, cortisol has more often been reflective of female reproductive status than of chronic stress. In this study, we addressed the hypothesis that wild golden lion tamarin ( Leontopithecus rosalia ) females, whose social structure is characterized by low aggression and high social support, …
Energy intake, energy expenditure, and reproductive costs of female wild golden lion tamarins (Leontopithecus rosalia)
Callitrichid females are often described as energetically constrained. We examined the energy budgets of 10 female wild golden lion tamarins (GLTs, Leontopithecus rosalia) in an effort to understand how energy intake and expenditure might influence physical condition and therefore reproductive performance. We used focal animal sampling to record behavioral data and conducted energy analyses of foods consumed by GLTs to estimate intake and expendi…
Are Behavioral Effects of Early Experience Mediated by Oxytocin
Early experiences can alter adaptive emotional responses necessary for social behavior as well as physiological reactivity in the face of challenge. In the highly social prairie vole (Microtus ochrogaster), manipulations in early life or hormonal treatments specifically targeted at the neuropeptides oxytocin (OT) and arginine vasopressin (AVP), have long-lasting, often sexually dimorphic, consequences for social behavior. Here we examine the hypo…
Differences in Titi Monkey ( Callicebus cupreus ) Social Bonds Affect Arousal, Affiliation, and Response to Reward
Titi monkeys ( Callicebus cupreus ) are a monogamous, New World primate. Adult pair‐mates form a bidirectional social bond and offspring form a selective unidirectional bond to their father. Some of the neurobiology involved in social bonds and maternal behavior is similar to the neural circuitry involved in nonsocial reward. Due to these overlapping mechanisms, social states may affect responses to external rewarding stimuli. We sought to determ…
Hormonal and Experiential Predictors of Infant Survivorship and Maternal Behavior in a Monogamous Primate ( C allicebus cupreus )
To better understand the roles that hormones and experience play in infant survival and maternal behavior in a biparental primate species, we analyzed urinary estrone ( E 1 C ) and pregnanediol glucuronide ( PdG ) from 24 socially housed titi monkey ( C allicebus cupreus) females over 54 pregnancies ( N = 1,430 samples). Pregnancies were categorized according to whether the infant survived ( N = 35) or not ( N = 19), and by maternal parity (primi…
Why primate models matter
Research involving nonhuman primates (NHPs) has played a vital role in many of the medical and scientific advances of the past century. NHPs are used because of their similarity to humans in physiology, neuroanatomy, reproduction, development, cognition, and social complexity-yet it is these very similarities that make the use of NHPs in biomedical research a considered decision. As primate researchers, we feel an obligation and responsibility to…
Population genetics of the California National Primate Research Center’s (CNPRC) captive Callicebus cupreus colony
Pair-Bonding in Other Mammals
Pair-bonding is a behavioral construct central to adult human relationships and is also displayed in some other mammalian species (primarily ones which display monogamy as a social system). These other mammal species have given us the opportunity both to refine our definition of pair-bonding and to investigate its neurobiological substrates.
Alternative Models for Small Samples in Psychological Research
Unavoidable sample size issues beset psychological research that involves scarce populations or costly laboratory procedures. When incorporating longitudinal designs these samples are further reduced by traditional modeling techniques, which perform listwise deletion for any instance of missing data. Moreover, these techniques are limited in their capacity to accommodate alternative correlation structures that are common in repeated measures stud…
Laboratory simulations of mate‐guarding as a component of the pair‐bond in male titi monkeys, Callicebus cupreus
Mate-guarding and territorial aggression (both intra- and inter-sexual) are behavioral components of social monogamy seen in male coppery titi monkeys (Callicebus cupreus) both in the field and in the laboratory. Methodology for studying these behaviors in captivity facilitates the translation of questions between field and laboratory. In this study, we tested whether exposure to a mirror would stimulate mate-guarding behavior in male titi monkey…
Development of a partner preference test that differentiates between established pair bonds and other relationships in socially monogamous titi monkeys ( Callicebus cupreus )
Partner preference, or the selective social preference for a pair mate, is a key behavioral indicator of social monogamy. Standardized partner preference testing has been used extensively in rodents but a single test has not been standardized for primates. The goal of this study was to develop a partner preference test with socially monogamous titi monkeys (Callicebus cupreus) adapted from the widely used rodent test. In Experiment 1, we evaluate…
“Monogamy” in Primates
This paper is the introduction to a special issue on "'Monogamy' in Primates: Variability, Trends, and Synthesis." The term "monogamy" has undergone redefinition over the years, and is now generally understood to refer to certain social characteristics rather than to genetic monogamy. However, even the term "social monogamy" is used loosely to refer to species which exhibit a spectrum of social structures, mating patterns, and breeding systems. P…
Effects of pair bonding on dopamine D1 receptors in monogamous male titi monkeys ( Callicebus cupreus )
Pair bonding leads to increases in dopamine D1 receptor (D1R) binding in the nucleus accumbens of monogamous prairie voles. In the current study, we hypothesized that there is similar up‐regulation of D1R in a monogamous primate, the titi monkey ( Callicebus cupreus ). Receptor binding of the D1R antagonist [ 11 C]‐SCH23390 was measured in male titi monkeys using PET scans before and after pairing with a female. We found that within‐subject analy…
Infant titi monkey behavior in the open field test and the effect of early adversity
The open field test is commonly used to measure anxiety-related behavior and exploration in rodents. Here, we used it as a standardized novel environment in which to evaluate the behavioral response of infant titi monkeys (Callicebus cupreus), to determine the effect of presence of individual family members, and to assess how adverse early experience alters infant behavior. Infants were tested in the open field for 5 days at ages 4 and 6 months i…
Effect of reward type on object discrimination learning in socially monogamous coppery titi monkeys ( Callicebus cupreus )
Highly valued food items are often used as rewards to reinforce an animal's behavior. For social species, social interaction is rewarding and can drive an individual's behavior as well. In the currently study, we wanted to compare the efficacy of a food reward and a social reward on object discrimination learning in socially monogamous titi monkeys. We hypothesized that titi monkeys would perform more accurately for a social reward (their pair ma…
Effects of aggressive temperament on endogenous oxytocin levels in adult titi monkeys
Coordination of oxytocin (OT) activity and partner interactions is important for the facilitation and maintenance of monogamous pair bonds. We used coppery titi monkeys (Callicebus cupreus) to identify the effects of male aggressive temperament on OT activity, affiliative partner-directed behaviors, aggressive partner-directed behaviors, anxiety-related behaviors, and hormone-behavior interactions. We used a mirror technique, simulating an intrud…
Oxytocin, vasopressin, and primate behavior
It has become increasingly clear that the nonapeptide hormones oxytocin and vasopressin have more diverse behavioral and physiological effects across species and across individuals than was initially recognized. To reflect this variation, we would like to introduce our Special Issue, entitled Oxytocin and Vasopressin in Primate Behavior, by celebrating the diversity that is found across the articles within it. While every article directly address…
American Journal of Primatology
Psychobiological development in primates
Relationship tenure differentially influences pair‐bond behavior in male and female socially monogamous titi monkeys ( Callicebus cupreus )
Pair‐bonded primates have uniquely enduring relationships and partners engage in a suite of behaviors to maintain these close bonds. In titi monkeys, pair bond formation has been extensively studied, but changes across relationship tenure remain unstudied. We evaluated differences in behavioral indicators of pair bonding in newly formed (~6 months paired, n = 9) compared to well‐established pairs (average 3 years paired, n = 8) of titi monkeys ( …
Coppery titi monkey ( Plecturocebus cupreus ) pairs display coordinated behaviors in response to a simulated intruder
Mate guarding and coordinated behaviors between partners are important for the maintenance of monogamous pair bonds. To study the effects of a perceived unfamiliar social intruder on females' behavior, we used coppery titi monkeys ( Plecturocebus cupreus ). We examined the effects of male aggressive temperament on females' behavior and the effects of each behavior performed by the male on the same female behavior. Using a mirror, we simulated a s…
Biology (22 works) · Psychology (21 works) · Primate Behavior and Ecology (20 works) · Neuroendocrine regulation and behavior (17 works) · Primate (15 works) · Developmental psychology (13 works) · Zoology (13 works) · Evolutionary Psychology and Human Behavior (11 works) · Ecology (10 works) · Medicine (9 works)