Pair Bond Formation Research Articles

The Relationship of Pair-Bond Formation and Duration to Reproductive Success in Short-Tailed Shearwaters Puffinus tenuirostris

A substantial correlation exists between the breeding ages of short-tailed shear-waters in pair-bonds. Much of this correlation can be explained by prolonged pair-bonds between the same mates, and the predominant availability of unpaired, inexperienced birds. Using Monte Carlo simulation, a comparison of the differences in age observed between pair members with those produced assuming random pairing of available birds, indicated some weak assortative mating on the basis of breeding age. The probability of breeding success depended both upon the breeding ages of the partners and upon the length of time they had bred together; the latter appeared the stronger effect. In the first year of a pair-bond, the breeding age of the female had a much stronger effect than that of the male in determining the probability of reproductive success.

Sexual differences in posture-related human behavior on subway trains, and their biological function

Posture-related behaviors of subway passengers, especially ones standing near the door, were examined. Observations of individuals standing alone revealed that: 1) Males tend to lift their arms higher (MAH), and females tend to hold their arms lower (FAL). 2) Females tend to stand facing the door. Males often take a converse orientation, and face other passengers. 3) The MAH·FAL tendency is the most conspicious in people in their 20s. Observation of a couple (a male and a female) standing together indicated that: 1) the MAH·FAL tendencies become more pronounced in a ‘couple’ situation than in a “solitary” situation. 2) The male tends to stand with the partner-female positioned between him and the door. The MAH·FAL becomes the most pronounced in this couple position. These results suggest that MAH·FAL is related to maintenance and formation of a sexual pair bond between a male and a female by functioning as sexual messages.

Waterfowl ecology and management

This new book represents a major revision of the first edition and addresses all aspects of waterfowl ecology and management under one cover. The second edition is expanded to 2,800 references arrayed across 11 chapters, such as classification, courtship behavior and pair-bond formation, reproduction, feeding ecology, breeding and winter periods, mortality and harvest management, wetlands and wetland management, major waterfowl habitats, and policy and administration. The new edition also includes 16 infoboxes, which are stand-alone inserts in the various chapters. The infoboxes present information on important waterfowl people, places, and issues. Coverage also has been expanded to address important waterfowl habitats around the globe and address a broad array of issues and examples of waterfowl ecology from the international literature.

Oxytocin administered centrally facilitates formation of a partner preference in female prairie voles (Microtus ochrogaster).

Prairie voles (Microtus ochrogaster) are monogamous mammals that form male-female pair bonds. Partner preference formation, one component of the pair bond in prairie voles, occurs following male-female cohabitation and is facilitated by mating. The peptide hormone oxytocin is released during physical contact and particularly following vaginal stimulation. Oxytocin has been implicated in mother-infant bond formation. The present study tested the hypothesis that oxytocin participates in the partner preference component of pair bond formation in adult prairie voles. Ovariectomized female prairie voles were implanted with osmotic mini-pumps releasing oxytocin (1-100 ng/h) or artificial cerebrospinal fluid (CSF). Pumps were implanted intracerebroventricularly or subcutaneously and females then were housed for 6 h with a male partner, followed by a preference test in which females could elect to spend time with either the partner or an unfamiliar male. Females in groups that received centrally-administered oxytocin (10 or 100 ng/h), but not CSF, exhibited a significant preference for the partner present during infusion. The induction of a partner preference after oxytocin administration appeared specific for central oxytocin pathways as peripheral oxytocin administration was ineffective. Moreover, central administration of a selective oxytocin receptor antagonist inhibited the behavioral effect of exogenous oxytocin. These results suggest that oxytocin may be one factor contributing to the development of partner preferences in this monogamous rodent.

Is sexual-aggressive vocal communication related to asymmetric mechanisms in the brain?

In Mongolian gerbil males, a reliable asymmetric relationship has been discovered between a stereotyped ultrasonic vocalizattion and the volume of a discrete nucleus within the preoptic-anterior hypothalamic area, the sexually dimorphic area, pars compacta (SDApc). The steroid-sensitive ultrasonic, emitted at high levels during courtship interactions, is associated with the absence of aggressive encounters and appears to be necessary for the formation and maintenance of pair-bonds with females. Interactions between unfamilliar, non-pair-bonded adult male and estrous female gerbils result in male aggression, reduction of male ultrasonic calling, and disruption of normal female dartmale follow sociosexual sequences. Castration further reduces ultrasonic calling, inhibits normal sociosexual sequences, and increses aggression in interaction between unfamiliar compared to pair-bonded individuals. Bothg brain structure and lateralization of vocal function in males depend on the action of sex steroids during sexual differentiation and in adulthood. Thus, the gerbil provides a new model to study steroid-dependent lateralization of brain mechanisms of vocal behavior mediating aggressive-sexual relationships. © 1994 Wiley-Liss, Inc.

Development of partner preferences in female prairie voles ( Microtus ochrogaster): The role of social and sexual experience

Prairie voles ( Microtus ochrogaster) exhibit a monogamous mating system characterized by long-term pair bonds between mates. The purpose of this study was to examine the effect of cohabitation time and sexual experience on the development of pair bond formation in female prairie voles. Females that were allowed to cohabit for 24 hr or more, with or without mating, exhibited a strong social preference for a familiar partner versus a strange male. Females that cohabited and mated for 6 hr showed strong preferences for a familiar partner, while cohabitation for less than 24 hr, without mating, did not result in preferences for the familiar male. These results indicate that mating was not essential for partner preference formation; however, preferences developed more rapidly when mating occurred.

Annual Variation in Return Rate, Mate and Nest-Site Fidelity in Breeding Gentoo and Macaroni Penguins

Annual variation in return rate of breeding birds, mate and nest-site fidelity was studied in the resident Gentoo (Pygoscelis papua) and migratory Macaroni (Eudyptes chrysolophus) Penguin from 1986 to 1990 at Bird Island, South Georgia (54S, 38?W). Return rates (proportion of birds breeding in year x which returned to breed in year x + 1) varied significantly between years: 20-79% and 35-73% in Gentoo and Macaroni Penguins, respectively. Lowest values in both species (in 1987) followed a severe, prolonged winter and were associated with delayed onset of breeding and decreased breeding population size. Decreased return rate was caused by (a) extensive non-breeding in adult birds: 25% of Gentoo and 14% of Macaroni Penguins which bred in 1986 were alive but failed to breed in 1987, and (b) increased adult mortality. Mate fidelity also varied between years in Gentoo Penguins (0-89%) with no birds retaining the same mate in 1987. In contrast, in Macaroni Penguins mate fidelity was high (71-79%) in all three years. This difference may be due to the shorter pre-breeding period, greater synchrony of arrival and pattern of continuous nest attendance in Macaroni Penguins. Failed breeders were more likely to change mate in Macaroni, but not Gentoo, Penguins but there was no difference in subsequent breeding success or mean laying date between new and established pairs in either species. Both species showed a high degree of nest-site fidelity in all years (Gentoo, 89-100%; Macaroni 69-87%). Females were more likely than males to change nest-site following mate change. Intra-season pair fidelity was high in Macaroni Penguins (74-78%) between breeding and the post-nuptial molt. However, the post-nuptial molt was also an important period for formation of new pairbonds in this species. Despite marked differences in breeding chronology and life-history patterns in these two species, return rates, mate and site fidelity were only markedly dissimilar in one of the three years studied.

Oxytocin and social bonding.

The prairie vole is an excellent model for examining the neurobiology of social attachment, and in particular of pair-bond formation. In female prairie voles either sexual interactions or oxytocin infusions can hasten the formation of a partner preference. These results implicate oxytocin in the formation of adult heterosexual social bonds. In conjunction with work on other social systems described in this volume, these findings also support the suggestions of Klopfer and Newton that oxytocin may be important in coordinating mammalian social interactions with other critical reproductive events such as birth, lactation, and sexual behavior.

Frequency of Female Copulations with Multiple Males and Sexual Selection

Female animals often copulate with more than a single male during one fertile period. I suggest that female propensity to engage in such multimale copulations is caused by constraints on female mate choice set by the availability of males. A simple graphic model of mate choice after formation of pair bonds suggests that the probability of female engagement in copulations with multiple males should be inversely proportional to the availability of preferred mates at the time of mate choice. This problem will be present whenever males and females establish pair bonds, and the male availability constraint on female mate choice will be more important for mating systems in which males attract only a single or few females. Monogamy thus particularly often sets the stage for sexual selection via multiple matings. Male availability to females during mate choice differs between mating systems, and the relative frequency of female copulations with multiple males should be inversely related to male availability. If f...

Environmental and hormonal factors in seasonal breeding in free-living male Indian rose-ringed parakeets ( Psittacula krameri)

Seasonal changes in testicular activity, plasma luteinizing hormone (LH), estradiol (E 2), testosterone (T), and 5 α-dihydrotestosterone (5 α-DHT) were related to pair bond formation, nest building, nest defense, and parental behavior in freeliving Indian rose-ringed parakeets ( Psittacula krameri) in northwest India. Spermatozoa production occurred between January and March when daylengths were short (10–12 hr) and ambient temperature was seasonally low (8–20 °C). At other times of the year the testes were regressed. Plasma LH levels increased during the prebreeding period (September–December) when the birds were forming pairs and selecting or defending nest sites. Plasma LH levels increased further between January and March and decreased to seasonal low values during the post breeding period between April and June when the birds were caring for young. Concentrations of plasma androgens and estrogens were similar during the prebreeding and postbreeding phases of the breeding cycle. During the breeding period, the ratios between plasma 5 α-DHT and testosterone and between plasma estradiol and testosterone increased. It is proposed that the absence of marked seasonal changes in plasma steroid levels is related to nest defense behavior which occurs during the prebreeding, breeding, and postbreeding phases of the breeding cycle. Winter breeding makes it possible for the parakeets to avoid competition with other birds for nesting sites, to avoid fledging young during the monsoon period, and to take advantage of the winter pea crop which provides the female with extra nutrients for egg production.

Environmental, dietary, and hormonal factors in the regulation of seasonal breeding in free-living female Indian rose-ringed parakeets ( Psittacula krameri)

The roles of environmental, dietary, and hormonal factors in the timing of seasonal breeding were assessed in free-living female Indian rose-ringed parakeets, Psittacula krameri, in northwest India (22 ° 2′N, 73 °E). The ovaries and oviducts began to enlarge in January, were fully developed in February, and began to regress in March. During this time there was no significant change in the concentration of plasma luteinizing hormone (LH) or estradiol. The concentration of plasma LH decreased ( P < 0.01) at the end of the breeding season. Pair bond formation occurred between September and December and was associated with an increase in levels of plasma LH but no change in plasma estradiol. Concentrations of plasma testosterone (T) and 5α-dihydrotestosterone (5α-DHT) did not vary significantly during the year and were similar to those in males except for higher values of 5α-DHT and lower values of T during the pre- and postbreeding periods, respectively. The similar levels of plasma androgens in both sexes may be related to the equal roles that both sexes play in the defence of their nest holes. An analysis of crop sac contents showed that the birds fed chiefly on pigeon peas ( Cajanus cajan) during the breeding season and on cereal grains at other times of the year. It is suggested that pigeon peas provide the extra nutrients, including calcium, required for egg production. Since pigeon peas ripen between November and March, the production of the crop may play a role in the timing of seasonal breeding. A further factor appears to be competition for nest sites. By breeding in winter, the parakeet avoids competing with other species which nest in holes.

Sociosexual development, pair bond formation, and mechanisms of fertility suppression in female cotton-top tamarins (Saguinus oedipus oedipus).

The effect of various social environments on sociosexual behavior was examined in six young female cotton-top tamarins (Saguinus oedipus oedipus) and in three established breeding females. Behavioral observations and hormonal samples were collected on young females while they were living with their families, when they were isolated from conspecifics, and after they were paired with an unrelated male. While living with the family, all females showed a suppression of fertility and low frequencies of sociosexual behavior. Following removal from the family, isolated females displayed an increase in rate of scent marking and an increase in hormonal levels. When young females were paired with males, they were exposed to scent secretions from their natal families, from an unfamilar family, and from a control for a total of 24 weeks. After pairing, hormonal levels increased dramatically, and ovarian cyclicity began. An increase in sociosexual behavior and elevated levels of scent marking accompanied this physiological change. Newly paired females had higher rates of affiliative behavior and scent marking than did established breeding females. However, both newly paired and established breeding males were more likely to initiate contact, grooming bouts, and social sniffing than were females. Time to first ovulation was later in females who were exposed to scent secretions from their natal families than it was in those females given a control for the first 8 weeks following pairing. No female conceived during exposure to scent secretions. However, once normal ovarian cycling had begun or a pregnancy was established, exposure to scent secretions had no effect. Thus, the social environment influences the fertility, sociosexual behavior, and pair bond formation of cotton-top tamarins. In addition, chemical stimuli found in the scent secretions produced by the natal family are most likely involved in reproductive suppression.

Effects of Body Weight and Age on the Time of Pairing of American Black Ducks

Abstract I used captive young and adult American Black Ducks (Anas rubripes) during October-February 1984-1985 to test whether body weight and age affected time of pair-bond formation. Eighty ducks were marked individually, and 10 ducks (6 males and 4 females, half of each age class) were assigned to each of 8 experimental pens. Ducks in 4 pens received an ad libitum diet of commercial duck food, and ducks in the other 4 pens received a restricted ration of the same food. During early winter ducks in both groups gained weight, but ducks on the restricted diet gained less than birds on the ad libitum diet; peak winter weight of ducks on the ad libitum diet averaged 22% greater than initial body weight compared with 6.5% for ducks on the restricted diet. In late winter ducks on the restricted diet lost 28.7% of peak winter weight, and ducks on the ad libitum diet lost 19.3%. Weight loss of ducks on the ad libitum diet began before weather conditions became severe and coincided with a reduction in food consumption. This result supports the idea that weight loss of waterfowl in late winter is controlled endogenously. Individuals on the ad libitum diet paired earlier than those on the restricted diet, and pair bonds were stronger. Adults of both sexes paired earlier than young ducks, but differences for females were not significant statistically. Age and energy constraints are factors that can affect intraspecific variation in pairing chronology.

Effects of PCBs on mourning dove courtship behavior.

The effects of PCBs on the Mourning sove courtship behavior and subsequent reproductive effects were studied. The behavior has been divided into the courtship phase (pair bond formation and courting) and the nesting phase (nestbuilding, egglaying, and incubation). Twenty four pairs of doves were fed 0, 10, or 40 ppm Aroclor 1254 for 42 days. The courtship phases were significantly prolonged at the higher dose. Both doses had effects on the nesting phase; at 10 ppm the initial nest building was about 7 days longer than that of controls. Clutch size and eggshell thickness did not significantly differ from controls. (JMT)

Factors affecting the formation and maintenance of pair bonds in the zebra finch, Taeniopygia guttata

There is evidence that the process of pair formation starts within minutes of the introduction of unfamiliar zebra finches. Males courted their eventual mates in preference to other females, and some females solicited their mates, during the first recording session of this study. The full establishment of the pair bond probably takes longer than this, because clumping and allopreening between mates were not usually recorded until the second or third bay of introduction. Tactile contact, between partners, or at least the opportunity for them to come close together, is important in bond formation, but established bonds can be maintained by auditory contact alone. Birds re-pair almost immediately in the total absence of the mate, but the formation of this new bond does not destroy the original one.

Behaviors Associated with Seasonal Reproduction and Long-Term Monogamy in Canada Geese

We measured seasonal changes in the incidence of various social behaviors performed by members of a captive flock of Canada Geese (Branta canadensis moffitti) in order to determine (a) which of these behaviors were associated with reproduction in a species with long-term monogamy, (b) sexual differences in their expression, and (c) their temporal relationship with nesting events. Breeding and nonbreeding geese were compared. Aggression, Triumph Ceremony, and Calling by breeding male geese reinforced pair bonds and were performed most frequently in the context of territorial display. The Triumph Ceremonies of breeding females also strengthened pair bonds and were probably essential for establishing a territory and reproductive success. Breeding males behaved aggressively most frequently before the initiation of nesting through the incubation period. During incubation, females became increasingly unresponsive to their mate's Triumph Ceremony and by the time their goslings were two weeks old the frequency of their aggressive behaviors was closer to that of their mates than at any other time of the year. These changes coincided with an increase in social gregariousness during brood rearing and molt. Retreat was more common in nonbreeding than breeding geese. Nonbreeding males were not aggressive and performed few Triumph Ceremonies. Their behavior did not elicit supportive responses from nonbreeding females and probably inhibited pair formation. The timing of reproduction of many avian species in seasonal habitats is confined by the periodic availability of resources (Lack 1968). Canada Geese (Branta canadensis) nest predominantly in northern latitudes (Delacour 1954, Palmer 1976) and reproductive events occur within a relatively short period of time. Nesting generally begins as soon as secure nest sites become available, and growth of goslings coincides with the growth of sedges and grasses during the summer (Maclnnes 1962, Vermeer 1970, Maclnnes et al. 1974, Raveling and Lumsden 1977, Raveling 1978). The timing of nesting is also influenced by intra-pair activities (Lofts and Murton 1973:81, Silver 1978) and social conditions (Lott et al. 1967). Formation of life-long pair bonds and intensification of mutual behaviors by pairs of Canada Geese before arrival on their breeding grounds permit nesting to begin without the delay of pair formation. The social behavior of Canada Geese is well documented (e.g., Hanson 1953, Collias and Jahn 1959, Klopman 1962, 1968, Brakhage 1965, Raveling 1970), but few investigators have quantified such behavior using individuals with known histories in a well defined social environment. In this paper, we report the frequency with which previously described behaviors were performed by breeding and nonbre ding Canada Geese (B. c. moffitti). Our objective was to identify behaviors that were important to intra-pair synchrony and nesting success in order to increase our understanding of the behavioral role of the sexes in a species that has long-term pair bonds and nests within a restricted period of time.

Time Budget, Niche Overlap, Inter- and Intraspecific Aggression in Anolis humlis and A. limifrons from Costa Rica

Observations of Anolis humilis and A. limifrons in wooded habitats at La Selva, Costa Rica, indicated that these similar-sized anoles occupied two largely separate vertical zones (A. limifrons above A. humilis). A time-budget analysis assessed the nature and frequency of intraspecific and interspecific interactions in natural, undisturbed anole populations and established field foraging sites in terms of perch height and diameter components of the structural habitat. Spatial coexistence must be considered the end result of combinations of complex variables, including species-specific foraging sites, heterogeneity of the habitat, low population densities, differences in the nature and frequency of intraspecies and interspecies interactions, and perhaps relatively abundant food. Conspecifics demonstrated aggressive interactions and ritualized display behavior corresponding to territorial defense and, in A. limifrons, pair-bond formation. Congeners interacted infrequently and failed to evidence conspicuous aggression between species populations at natural densities.

Structural aspects of the metal-insulator transitions in (Ti 0.9975V 0.0025) 4O 7

The structure of (Ti 0.9975V 0.0025) 4O 7 has been refined at 298, 135, and 100°K from single-crystal X-ray diffraction data. This sample belongs to the region of the Ti 4O 7 V 4O 7 phase diagram where still two electrical transitions are observed. The three structures of the V-doped sample are almost identical to the corresponding structures of pure Ti 4O 7. The charges are disordered in the metallic phase, they order very slightly in the intermediate phase, and they are almost completely ordered along the 3113 and the 4224 chains in the low-temperature phase. There is no evidence of cation pair-bond formation in the intermediate phase, whereas the Ti 3+ cations are all paired in the low-temperature phase. The cationic Debye-Waller factors in the intermediate phase are anomalously large, which is indicative of a disorder. Thus, in order to explain the physical properties of the intermediate phase, as in the case of the pure sample, all the Ti 3+ cations are thought to form pair bonds with no long-range order. The TiTi distances along the pseudorutile c-axis are shorter in the V-doped sample than in the pure one. This indicates that the relative bond strengths increase with the incorporation of vanadium. The main difference between pure Ti 4O 7 and (Ti 0.9975V 0.0025) 4O 7 is in the lattice parameters and unit-cell volume variations with temperature. In the latter sample two discontinuities are observed, each corresponding to one transition, whereas in the former only one transition is observed, which corresponds to the higher transition. In the low-temperature phase the V cations are either 3+ or 4+ and are either on the 3113 chains or on the 4224 chains. The V doping gives rise to four different patterns. Each one is discussed in order to explain the differences between V-doped sample and pure Ti 4O 7.

Social interactions between peromyscus leucopus and P. gossypinus in captivity

In evaluating the role of behavioral interactions in the maintenance of ecological and ethological isolation in sympatric populations of P. leucopus and P. gossypinus, the interspecific behavior of 94 animals in all possible sex pair combinations was observed in 84 staged dyadic trials of 15-minutes duration. Qualitatively the patterns of behavior differed little between sexes or species. Despite a high inter-individual variability and the high proportion of amicable interactions, the mean frequency of occurrence of aggressive behavior as well as the number of trials in which aggressive behavior occurred was greater in trials of animals from areas of range sympatry in comparison with those of the control animals from areas of range allopatry. Although the dominance relationships in many trials were unclear, gossypinus nonetheless consistently dominated leucopus. These data combined with examination of the habitats of these mice where their ranges do not overlap suggest that agonistic interactions may implement species integrity either primarily by Limiting or preventing the occupancy by leucopus of areas in which gossypinus occurs or secondarily by reducing the chances of pair bond formation.

The Mortality, Behavior, and Homing of Transplanted Juvenile Canada Geese

During the summers of 1967 and 1968, 273 flightless 7-and 8-week-old Canada geese (Branta canadensis maxima) were transplanted about 100 miles from their natal lakes near Brooks, to release sites northeast of Hanna, Alberta. All transplants received leg bands and colored neck collars for field identification. A preflight mortality of 4 percent was calculated. Postflight locations, identity, and behavior of transplants were recorded. Feeding was the major daily preflight activity of transplants, and occurred most intensively at sunrise and sunset. Resident geese were dominant over transplants. Non-breeding resident geese were more tolerant of transplants than were breeding pairs. The postflight movements of transplants were localized and as a unit under the leadership of resident birds. Transplants on release sites unoccupied by resident geese dispersed from these lakes in small groups immediately after attaining flight. From 68 birds of each sex (136) transplanted in 1967, 13 homing female yearlings were recorded in the spring of 1968. In the spring of l969, 22 females and 22 males vere observed cyn the area from a potential of 64 males and 73 females transplanted the previous summer. Homing of yearling females was significantly (P < 0.05) higher than for yearling males. Eighty-five and 86 percent of the initial sightings of yearling females in 1968 and 1969 respectively, were on or within 1 mile of their release sites. In 1969, 32 percent of the initial sightings of yearling males were on or within 1 mile of their release sites. Eighty percent of the homing yearlirlg females formed pair relationships during 1968 and 196g, with 68 percent occurring on the study area. Females appeared attracted to their release sites whether they were paired or unpaired. Sixty-eight percent of the yearling males showed pairing tendencies in 1969. Twenty-seven percent of these pair associations occurred on the study area. Of the yearling males returning, only those forming pair associations remained on the study area for 30 days or longer. Apparently the males were more attracted to the females in the pair associations than to their release sites. The pair bonds of some of the yearling females appeared to become unstable just prior to the summer molt migration C'o 2-year-old males were known to home to the area. Five 2-year-old females homed to and paired on their release sites. One 2-year-old female nested and successfully raised a brood of 5 goslings. The natural dispersion of large Canada geese throughout their original breeding range, as delineated by Hanson ( 1965 ), can best be described as slow, even under optimum habitat conditions. This lack of pioneering may be due to certain physiological and behavioral characteristics. Mayr ( 1942 ) stated that strong intrafamily bonds played an important role in the subspeciation of Canada geese over areas where geographic barriers were lacking. With reference to geese in general, Johns1 A joint contribution from the Alberta Fish and Wildlife Division and the Zoology and Entomology Department, Montana State University, Bozeman. Published as Journal Series 156. Montana Agricultural Experiment Station. 2 Present Address: 411 28 Avenue, N. W., Calgary 43, Alberta, Canada. gard ( 1965 ) attributed slow increase in numbers and lack of gene mixing to delayed maturation and permanency of pair bonds respectively. Sherwood ( 1967) confirmed the formation of both pair and intrafamily bonds. He also found a lack of dispersion from the natal area, particularly by females. Because Canada geese are important for their aesthetic and sporting qualities, biologists have attempted to artificially establish lo-cal breeding populations by using captive flocks or by transporting and releasing juveniles. These attempts have produced variable results. Pirnie ( 1938 ) concluded that the restocking of Canada geese by captive flocks was successful in southern Michigan. Williams and Kalm-