Alternative Mating Tactics in Socially Monogamous Prairie Voles, Microtus ochrogaster

Alternative mating tactics appear to evolve when sexual selection is strong. Because such conditions are usually observed in species with polygynous or polyandrous mating systems, alternative mating tactics in monogamous mating systems are seldom documented and are poorly understood. In prairie voles, Microtus ochrogaster, a species widely known for forming monogamous pair-bonds, the expression of territoriality within each sex is dimorphic, and includes non-territorial “wanderers” as well as territorial “residents.” To explore the variance in fitness, measured in offspring numbers, among breeding individuals expressing these alternative mating tactics, we compiled parentage data over 3 years for male and female prairie voles from natural populations in Indiana and Kansas, USA. We found that: (1) the average fitnesses of males and females within each population were identical when adjusted by the sex ratio; (2) the variance in fitness in male and female prairie voles was comparable to that of highly polygynous species; (3) The average fitnesses of male tactics, and of female tactics, were equivalent within and among years within each location; (4) consistent with negative frequency-dependent selection acting on mating phenotypes, the between-tactic variance in fitness for male and female mating tactics decreased with increasing study duration; (5) consistent with negative assortative mating, resident males, and wanderer females produced offspring primarily in monogamous partnerships, whereas wanderer males and resident females produced offspring primarily in polygamous partnerships. Our results show that the conditions necessary for the persistence of alternative mating tactics are indistinguishable from those for phenotypically less flexible alternative mating strategies, and that alternative mating tactics can evolve in both sexes in monogamous species when fitness variance within each sex is large

Factors Determining the Effects of Human Interaction on the Cortisol Levels of Shelter Dogs

Dogs admitted to animal shelters experience psychological stressors resulting in elevated plasma cortisol. We previously found 30 min of human interaction reduced this response. The present study further characterized this effect, with the aim of developing a practical means of reducing stress of shelter dogs. We found that a second day of 30 min of petting reduced cortisol levels as effectively as the first. Further, 15 min of this interaction was as effective as 30 min. During petting, signs of excitation (vocalizations) and anxiety (panting) as well as escaped attempts were reduced, and social solicitation (tail-wagging) increased. However, cortisol levels quickly increased when dogs were returned to the home kennel. Cortisol reductions were pronounced in dogs admitted as strays, but human interaction did not reduce cortisol in a subpopulation relinquished by their owners. We also measured hair cortisol levels to assess stress prior to shelter admittance. Strays and dogs released by their owners showed comparable hair cortisol levels that were intermediate to those of pet dogs living in a home and those of dogs diagnosed with Cushing\u27s disease. The findings show that as little as 15 min of human interaction can moderate cortisol levels of shelter dogs, that the effect is relatively temporary, that source of the dog is an important variable, and that hair cortisol accumulation may be useful to estimate the condition of the dog prior to shelter admittance

Enrichment Centered on Human Interaction Moderates Fear-Induced Aggression and Increases Positive Expectancy in Fearful Shelter Dogs

Some otherwise non-aggressive dogs may display fear-induced aggression under stressful conditions. Admittance to an animal shelter is a stressful experience for dogs, and aggression is often used as a criterion by shelters for precluding opportunities for adoption. We, therefore, examined whether a program of enrichment centered around a form of human interaction known to reduce the stress of shelter dogs would also reduce the aggression of fearful dogs and improve their general welfare. Fearful dogs displaying signs of aggression, as well as dogs displaying neither fear nor aggression, either did or did not receive 30 min a day of human interaction in a secluded room for approximately the first 5 days in a shelter. We then determined the number of enriched and non-enriched fearful and non-fearful dogs that passed a standard test of dog aggression as typically implemented in this shelter to determine eligibility for adoption. We also examined the affective state of dogs in a test of cognitive bias. In two separate experiments, we found that most fearful dogs without enrichment failed the aggression test, whereas most fearful dogs undergoing enrichment completed this assessment successfully (P \u3c  0.001 in each experiment). In contrast, nearly all non-fearful dogs passed the aggression test regardless of enrichment experience. In cognitive bias testing, enrichment reduced the latency at which fearful dogs approached two locations at which the likelihood of reinforcement was ambiguous, a measure of increased positive expectancy (P”s \u3c 0.01). Unexpectedly non-fearful dogs receiving enrichment approached one of the ambiguous locations more slowly than non-enriched controls (P \u3c  0.05), a finding that might be an artifact of the testing procedures used here. While the generality of the results needs to be tested in other populations and shelter environments, the findings: 1) document the vulnerability of dogs exhibiting fear-induced aggression in a shelter environment; 2) demonstrate the ability of an enrichment program focusing on human interaction to reduce aggressiveness in these dogs and thereby increase their chances of being offered for adoption; and, 3) indicate a more-general outcome of the enrichment procedure on the affective state of fearful dogs

Enrichment Centered on Human Interaction Moderates Fear-Induced Aggression and Increases Positive Expectancy in Fearful Shelter Dogs

Some otherwise non-aggressive dogs may display fear-induced aggression under stressful conditions. Admittance to an animal shelter is a stressful experience for dogs, and aggression is often used as a criterion by shelters for precluding opportunities for adoption. We, therefore, examined whether a program of enrichment centered around a form of human interaction known to reduce the stress of shelter dogs would also reduce the aggression of fearful dogs and improve their general welfare. Fearful dogs displaying signs of aggression, as well as dogs displaying neither fear nor aggression, either did or did not receive 30 min a day of human interaction in a secluded room for approximately the first 5 days in a shelter. We then determined the number of enriched and non-enriched fearful and non-fearful dogs that passed a standard test of dog aggression as typically implemented in this shelter to determine eligibility for adoption. We also examined the affective state of dogs in a test of cognitive bias. In two separate experiments, we found that most fearful dogs without enrichment failed the aggression test, whereas most fearful dogs undergoing enrichment completed this assessment successfully (P \u3c  0.001 in each experiment). In contrast, nearly all non-fearful dogs passed the aggression test regardless of enrichment experience. In cognitive bias testing, enrichment reduced the latency at which fearful dogs approached two locations at which the likelihood of reinforcement was ambiguous, a measure of increased positive expectancy (P”s \u3c 0.01). Unexpectedly non-fearful dogs receiving enrichment approached one of the ambiguous locations more slowly than non-enriched controls (P \u3c  0.05), a finding that might be an artifact of the testing procedures used here. While the generality of the results needs to be tested in other populations and shelter environments, the findings: 1) document the vulnerability of dogs exhibiting fear-induced aggression in a shelter environment; 2) demonstrate the ability of an enrichment program focusing on human interaction to reduce aggressiveness in these dogs and thereby increase their chances of being offered for adoption; and, 3) indicate a more-general outcome of the enrichment procedure on the affective state of fearful dogs

Enrichment Centered on Human Interaction Moderates Fear-Induced Aggression and Increases Positive Expectancy in Fearful Shelter Dogs

Some otherwise non-aggressive dogs may display fear-induced aggression under stressful conditions. Admittance to an animal shelter is a stressful experience for dogs, and aggression is often used as a criterion by shelters for precluding opportunities for adoption. We, therefore, examined whether a program of enrichment centered around a form of human interaction known to reduce the stress of shelter dogs would also reduce the aggression of fearful dogs and improve their general welfare. Fearful dogs displaying signs of aggression, as well as dogs displaying neither fear nor aggression, either did or did not receive 30 min a day of human interaction in a secluded room for approximately the first 5 days in a shelter. We then determined the number of enriched and non-enriched fearful and non-fearful dogs that passed a standard test of dog aggression as typically implemented in this shelter to determine eligibility for adoption. We also examined the affective state of dogs in a test of cognitive bias. In two separate experiments, we found that most fearful dogs without enrichment failed the aggression test, whereas most fearful dogs undergoing enrichment completed this assessment successfully (P \u3c  0.001 in each experiment). In contrast, nearly all non-fearful dogs passed the aggression test regardless of enrichment experience. In cognitive bias testing, enrichment reduced the latency at which fearful dogs approached two locations at which the likelihood of reinforcement was ambiguous, a measure of increased positive expectancy (P”s \u3c 0.01). Unexpectedly non-fearful dogs receiving enrichment approached one of the ambiguous locations more slowly than non-enriched controls (P \u3c  0.05), a finding that might be an artifact of the testing procedures used here. While the generality of the results needs to be tested in other populations and shelter environments, the findings: 1) document the vulnerability of dogs exhibiting fear-induced aggression in a shelter environment; 2) demonstrate the ability of an enrichment program focusing on human interaction to reduce aggressiveness in these dogs and thereby increase their chances of being offered for adoption; and, 3) indicate a more-general outcome of the enrichment procedure on the affective state of fearful dogs

Psychological Stress, Its Reduction, and Long-Term Consequences: What Studies with Laboratory Animals Might Teach Us about Life in the Dog Shelter

There is a long history of laboratory studies of the physiological and behavioral effects of stress, its reduction, and the later psychological and behavioral consequences of unmitigated stress responses. Many of the stressors employed in these studies approximate the experience of dogs confined in an animal shelter. We review how the laboratory literature has guided our own work in describing the reactions of dogs to shelter housing and in helping formulate means of reducing their stress responses. Consistent with the social buffering literature in other species, human interaction has emerged as a key ingredient in moderating glucocorticoid stress responses of shelter dogs. We discuss variables that appear critical for effective use of human interaction procedures in the shelter as well as potential neural mechanisms underlying the glucocorticoid-reducing effect. We also describe recent studies in which enrichment centered on human interaction has been found to reduce aggressive responses in a temperament test used to determine suitability for adoption. Finally, we suggest that a critical aspect of the laboratory stress literature that has been underappreciated in studying shelter dogs is evidence for long-term behavioral consequences—often mediated by glucocorticoids—that may not become apparent until well after initial stress exposure

Factors Determining the Effect of Human Interaction on the Cortisol Levels of Shelter Dogs

The stress experienced by dogs admitted to animal shelters not only impacts welfare, but may lead to behavior that threatens successful adoptions. This stress is reflected in an elevation in the plasma cortisol levels of newly admitted dogs. We previously found 30 min of human interaction reduced the plasma cortisol response dogs showed to shelter housing. The goal of the present study was to assess the practicality and effectiveness of the human interaction procedure as a means that volunteers and staff might use to reduce the stress of shelter dogs. We, therefore, investigated several parameters of the effect of human interaction on plasma cortisol concentrations and behavior that were chosen for their relevance to this goal. The current study found that a second day of 30 min of petting reduced cortisol levels as effectively as the first (P \u3c 0.05) and that 15 min of this interaction was as effective as 30 min. However, the reduction in cortisol concentrations did not persist when dogs were returned to the home kennel. During petting, signs of excitation (vocalizations) and anxiety (panting) as well as escape attempts were reduced, and social solicitation (tail-wagging) increased (P \u3c 0.05 for all behavioral effects). Cortisol reductions were pronounced in dogs admitted as strays (P \u3c 0.01), but human interaction did not reduce cortisol levels in a subpopulation relinquished by their owners. We also measured hair cortisol levels to assess stress prior to shelter admittance. Strays and dogs released by their owners showed comparable hair cortisol concentrations that were intermediate to those of pet dogs living in a home and those of dogs diagnosed with Cushing’s disease. These findings show that as little as 15 min of human interaction can moderate cortisol levels of shelter dogs. The cortisol reduction is repeatable and associated with positive behavioral change. However the effect is of short duration and appears to vary with the source of the dog. Finally the accumulation of cortisol in hair may be a useful method to estimate the condition of the dog prior to shelter admittance

Factors Determining the Effect of Human Interaction on the Cortisol Levels of Shelter Dogs

The stress experienced by dogs admitted to animal shelters not only impacts welfare, but may lead to behavior that threatens successful adoptions. This stress is reflected in an elevation in the plasma cortisol levels of newly admitted dogs. We previously found 30 min of human interaction reduced the plasma cortisol response dogs showed to shelter housing. The goal of the present study was to assess the practicality and effectiveness of the human interaction procedure as a means that volunteers and staff might use to reduce the stress of shelter dogs. We, therefore, investigated several parameters of the effect of human interaction on plasma cortisol concentrations and behavior that were chosen for their relevance to this goal. The current study found that a second day of 30 min of petting reduced cortisol levels as effectively as the first (P \u3c 0.05) and that 15 min of this interaction was as effective as 30 min. However, the reduction in cortisol concentrations did not persist when dogs were returned to the home kennel. During petting, signs of excitation (vocalizations) and anxiety (panting) as well as escape attempts were reduced, and social solicitation (tail-wagging) increased (P \u3c 0.05 for all behavioral effects). Cortisol reductions were pronounced in dogs admitted as strays (P \u3c 0.01), but human interaction did not reduce cortisol levels in a subpopulation relinquished by their owners. We also measured hair cortisol levels to assess stress prior to shelter admittance. Strays and dogs released by their owners showed comparable hair cortisol concentrations that were intermediate to those of pet dogs living in a home and those of dogs diagnosed with Cushing’s disease. These findings show that as little as 15 min of human interaction can moderate cortisol levels of shelter dogs. The cortisol reduction is repeatable and associated with positive behavioral change. However the effect is of short duration and appears to vary with the source of the dog. Finally the accumulation of cortisol in hair may be a useful method to estimate the condition of the dog prior to shelter admittance

Selective Social Buffering of Behavioral and Endocrine Responses and Fos Induction in the Prelimbic Cortex of Infants Exposed to a Novel Environment

In mammals, the presence of the mother can reduce or “buffer” stress responses of her young in threatening conditions. We compared the effect of the mother, a familiar littermate, and an unfamiliar adult male on three classes of response shown by guinea pig pups in a novel environment: short latency active behaviors, particularly vocalizing; slower developing passive behaviors that appear mediated by inflammatory mechanisms; and hypothalamic‐pituitary‐adrenal activity. We also examined Fos induction in the prelimbic cortex, a region hypothesized to mediate buffering effects. Only the mother significantly suppressed all classes of behavior. The greatest selectivity was observed for passive behavioral responses. Contrary to expectations, the adult male reduced plasma cortisol levels of pups as effectively as did the mother. The presence of the male also resulted in increased Fos induction in the prelimbic cortex and high levels of social interaction. Maternal buffering was not associated with prelimbic activity. These results confirm the ability of the mother to reduce active behavioral and HPA responses and suggest a specific maternal buffering effect on the later developing passive behavioral responses. The findings also demonstrate an unexpected ability of adult males to reduce HPA responses and raise the possibility that different social partners buffer HPA activity through different underlying processes

Selective Social Buffering of Behavioral and Endocrine Responses and Fos Induction in the Prelimbic Cortex of Infants Exposed to a Novel Environment

In mammals, the presence of the mother can reduce or “buffer” stress responses of her young in threatening conditions. We compared the effect of the mother, a familiar littermate, and an unfamiliar adult male on three classes of response shown by guinea pig pups in a novel environment: short latency active behaviors, particularly vocalizing; slower developing passive behaviors that appear mediated by inflammatory mechanisms; and hypothalamic‐pituitary‐adrenal activity. We also examined Fos induction in the prelimbic cortex, a region hypothesized to mediate buffering effects. Only the mother significantly suppressed all classes of behavior. The greatest selectivity was observed for passive behavioral responses. Contrary to expectations, the adult male reduced plasma cortisol levels of pups as effectively as did the mother. The presence of the male also resulted in increased Fos induction in the prelimbic cortex and high levels of social interaction. Maternal buffering was not associated with prelimbic activity. These results confirm the ability of the mother to reduce active behavioral and HPA responses and suggest a specific maternal buffering effect on the later developing passive behavioral responses. The findings also demonstrate an unexpected ability of adult males to reduce HPA responses and raise the possibility that different social partners buffer HPA activity through different underlying processes