bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of the Aromatase Inhibitor R76713 On Sexual Differentiation of Brain and Behavior in Zebra Finches
Authors: Balthazart Jacques , Absil Phillipe , Fiasse Veronique , Ball Gregory F. 
Published: April 2008

Abstract
Neonatal estradiol injections masculinize both the singing behavior and some morphological aspects of the song control nuclei in female zebra finches (Taeniopygia guttata), but there is to date no physiological evidence that estrogens are responsible for the differentiation of song and the song control nuclei in male zebra finches during normal ontogeny. Injections of estrogen into young males demasculinizes their copulatory behavior, so that it is difficult to understand how the same endocrine environment could simultaneously masculinize song and demasculinize copulation. Attempts to block early estrogen action in males have resulted in a paradoxical hypermasculinization of several aspects of the song control nuclei. In the present experiment, we tried to evaluate the role played by estrogens during zebra finch differentiation by blocking their secretion with the non-steroidal aromatase inhibitor, R76713 or racemic vorozole. Zebra finches received at 2-3 days post-hatch one Silastic implant filled with R76713 or left empty as a control. Implants were left in place until about 45 days of age and birds were then gonadectomized. At the age of 105 days, all birds received a Silastic implant filled with T and, starting two weeks later, they were repeatedly tested for singing and copulatory behavior during a period of 3 weeks. They were then perfused and their brains were analyzed by histological methods to measure the volume of the song control nuclei, HVc, RA, area X and MAN. Treatment with R76713 significantly decreased (± 50%) the number of song bouts produced by the birds but did not affect the copulatory behavior of the males. The behavior of females was not changed by the aromatase inhibitor and, in particular, no increase in mounting behavior was seen in the treated females. The presence of a strong sex dimorphism in the size of all 4 song control nuclei was confirmed but no significant effect of R76713 on these measures could be detected. These data are therefore consistent with the idea that estrogens are implicated in the differentiation of singing behavior in the zebra finch but the small amplitude of the behavioral effect observed and the absence of morphological effect suggest that either other factors also play a major role at this level or that higher doses or longer treatments with the aromatase blocker should be tested.
Courtship Food-Calling in Burmese Red Junglefowl: I. the Causation of Female Approach
Authors: VAN KAMPEN Hendrik S. 
Published: April 2008

AbstractThe present study was performed to examine why female Burmese red junglefowl (Gallus gallus spadiceus) approach a food-calling male. Females from three small groups were tested individually with a male under different conditions. Deprivation of food for 24 h did not affect the reaction of females to food-calling, showing that the feeding system is not crucially involved. This result makes it unlikely that courtship food-calling with inedible objects is a case of deception, as was suggested previously. Further it was shown that females willing to perform the sexual crouch and females low in the peck-order were more likely to approach food-calling. These factors were found to be interrelated and fear was suggested to play a crucial role both in inhibiting and modulating approach and in willingness to crouch. The data gathered on the involvement of the sexual system did not allow for any definite conclusions, but as an alternative it was suggested that females might approach courtship food-calling because it arouses curiosity, or, exploration.
A New Experiment To Verify the Spatial Range of Pigeons' Olfactory Map
Authors: Benvenuti S. , IOALÈ P. , Nacci L. 
Published: April 2008

Abstract
A series of tests with homing pigeons was carried out to verify the spatial range of their olfactory map. In each test, a group of experimental birds, which had been prevented from smelling ambient odours during the passive displacement, was compared to a group of controls which always had free access to olfactory information. Our results show that the range of unfamiliar area where pigeons are able to navigate on the basis of local cues is rather limited (less than 120 km from the home loft). Homeward orientation, however, normally occurs beyond the limits of the olfactory map as the birds are able to use odorous cues perceived during the initial part of the outward journey. Our results are in agreement with the "mosaic" hypothesis of pigeons' olfactory navigation.
Vulnerability To Predation in Baboon Populations
Authors: Cowlishaw Guy 
Published: April 2008

AbstractThis study investigates patterns of predation in Papio baboon populations across Africa. Using anecdotal reports collated from the primate and predator literature, the following analyses are conducted. First, the primary predators of baboons are identified. These are shown to be the terrestrial carnivores; in order of importance leopards, lions and hyena. Second, patterns of large felid predation on baboons are investigated in detail. In terms of prey selection, leopards are more likely to take (1) adults than juveniles and (2) males than females. While lion attacks are strictly diurnal, leopards will attack during both the day and night. However, both predators are usually limited to conducting attacks when and/or where visibility is limited. Leopards were about twice as successful as lions at hunting baboons. Nocturnal leopard hunts were more successful than diurnal hunts when twilight cases were excluded; in relation to this, leopard attacks at sleeping sites were more likely to end in prey capture than attacks at waterholes. Finally, patterns of baboon retaliation against predators revealed that males are more likely to retaliate than females and that such behaviour effectively deters predators. Males are particularly aggressive towards leopards, where in 4/11 cases the leopard was killed. These results may help to resolve a number of outstanding controversies regarding the nature of predation risk in baboons, indicating that diurnal predation is a substantial threat, that males are effective at deterring several predator species, particularly leopards, and that predators will successfully attack and capture males.
Self-Structuring in Artificial "Chimps" Offers New Hypotheses for Male Grouping in Chimpanzees
Authors: Te Boekhorst Irenaeus J.A. , Hogeweg Paulien 
Published: April 2008

AbstractChimpanzees live in societies that are characterised both by disorder and order. On the one hand, party size fluctuates in a randomlike fashion and party membership is unpredictable ; on the other hand, fundamental party structures are apparent; males are often in all-male parties whereas females remain mostly solitary. The customary sociobiological explanation is based on the assumptions that 1) competition for food favors solitariness (especially in females); 2) chimpanzee males share the costs of territorial defense against rivals from neighbouring communities and 3) genetical relatedness among males within a community compensates for fitness losses due to their competition for food and females. We point to some theoretical flaws in the reasoning that forms the basis of the current neo-Darwinistic model and to the lack of empirical data concerning male relatedness. Most importantly, chimpanzee-like party structures emerge by self-organisation in an artificial "world" in which "CHIMPs" do nothing more than searching for food and mates, without requiring any of the assumptions of the sociobiological model.
A Demographic Analysis of Male Life History and Social Structure of Mountain Gorillas
Authors: Robbins Martha M. 
Published: April 2008

AbstractTwenty-five years of demographic data on free-ranging mountain gorillas (Gorilla gorilla beringei) from the Karisoke Research Center, Rwanda were used to assess male life histories and the variation within the age-graded social structure. Group types include lone silver-backs, one-male, multimale, and all-male groups. Although 60% of gorilla groups in the Virunga population are one-male, a multimale structure may increase chances of survival and future reproductive success for males at three stages of their lives. Infants born in one-male groups appear more likely to die from infanticide than those in multimale groups. Immature males in one-male groups may face decreased future reproductive opportunities compared to males in multimale groups. Adult males in one-male groups lack possible partners for coalition formation during intergroup encounters. Demographic constraints, such as length of time to male maturation, coupled with intense male-male competition for mates may limit the number and duration of groups with a multimale structure. Individuals are not restricted to one group type for their entire adult lives and males that attain maturity in each group type may eventually reproduce. Variation in male reproductive success is based both on length of reproductive tenure and on the number of mates.
Olfactory Preferences in Newborn Lambs: Possible Influence of Prenatal Experience
Authors: Schaal Benoist , Orgeur Pierre , Arnould Cécile 
Published: April 2008

Abstract
The present study examined whether prenatal chemosensory experience influenced chemosensory-based orientation behaviour in newly-born lambs. Two experimental strategies were developed in order: (i) to analyse the responsiveness of lambs to odours extracted from the prenatal environment (experiments 1 and 4) and to odours their were never exposed to (experiment 2), and (ii) to analyse the neonatal consequences of a prenatal exposure to a novel odorant (experiment 3). In experiment 1, when simultaneously presented with amniotic fluid (AF) and distilled water in a double-choice test, lambs displayed a clear attraction to AF. In experiment 3, two groups of lambs received differing exposure to citral in utero: group I lambs were born to ewes fed a citral diet and group 2 lambs were born to ewes never exposed to citral (CI). They were assessed in a double-choice test contrasting CI and AF (experiment 2 indicates that CI was neither attractive nor aversive in naive lambs). Although control lambs showed a clear preference for AF over CI, those exposed to CI prenatally did not orient discriminately to either stimulus, suggesting that prenatal experience with CI may alter postnatal responsiveness to it. Experiment 4 tested the ability of lambs to discriminate between the chemosensory qualities of samples of own vs alien AF; lambs oriented preferentially to their own AF. These findings suggest that prenatal chemosensory experience may be stored by lambs for some time after birth and influence their search behaviour.
Play Signals as Punctuation: the Structure of Social Play in Canids
Authors: Bekoff Marc 
Published: April 2008

AbstractActions called play signals have evolved in many species in which social play has been observed. Despite there being only few empirical demonstrations, it generally is accepted that play signals are important in the initiation ("I want to play") and maintenance ("I still want to play") of ongoing social play. In this study I consider whether a specific and highly stereotyped signal, the bow, is used to maintain social play in adult and infant domestic dogs, infant wolves, and infant coyotes. To answer this question the temporal placement of bows relative to actions that are also used in other contexts (dominance or predatory encounters) such as biting accompanied by rapid side-to-side shaking of the head was analyzed to determine if bows performed during ongoing social play are used to communicate the message "I want to play despite what I am going to do or just did - I still want to play". The non-random occurrence of bows supports the hypothesis that bows are used to maintain social play in these canids when actions borrowed from other contexts, especially biting accompanied by rapid side-to-side shaking of the head, are likely to be misinterpreted.
Pod Characteristics of Migrating Humpback Whales (Megaptera Novaeangliae) Off the East Australian Coast
Authors: Brown Miranda , Corkeron Peter 
Published: April 2008

Abstract
The size and sex composition of migrating humpback whale pods were investigated off the east Australian coast. Two hundred and thirty one singletons, 257 pairs, 63 trios, 7 quads and 4 pods containing more than 5 individuals were observed during two land-based surveys carried out throughout the northward migration in 1991 and 1993. Generally humpback whales migrated northward towards the breeding area in pods of I or 2 individuals. In 1992, a biopsy study was carried out throughout the northward and southward migrations. Pods migrating southward (mean = 2.59, SE = 0.19) towards the feeding areas were significantly larger than those travelling north (mean = 1.75, SE = 0.03). The sex of 134 individuals in 63 complete pods was determined by molecular analysis of skin biopsies. Male humpback whales were found in larger pods than females. The most common pod type observed was the male-female pair, which is suggestive of either mating on migration and/or mate-guarding. Males were found associated together frequently. Competitive behaviour was observed during both the northward and southward migrations. The sexing of all individuals within 8 competitive pods indicated that not all contained a female. Although competitive behaviour was observed during the migration, most male-male associations were charactcrised by non-agonistic and occasionally cooperative interactions. We suggest there is a behavioural continuum on migration between the feeding and breeding grounds which is not governed solely by spatial proximity to the terminus. The pod characteristics of humpback whales on their return migration to the feeding grounds showed greatest similarity to those observed on breeding grounds elsewhere. In conclusion, our study showed that the migration of humpback whales is more
Patterns of Female Attractiveness in Indian Ocean Bottlenose Dolphins
Authors: Connor Richard C. , Richards Andrew F. , Smolker Rachel A. , Mann Janet 
Published: April 2008

Abstract
Hormonal profiles of captive individuals show that bottlenose dolphins (Tursiops spp.) are seasonally polyoestrous, but little is known of reproductive behaviour among free-ranging bottlenose dolphins. In Shark Bay, Western Australia, we have documented for the first time patterns of female attractiveness that may correspond to multiple oestrous cycles. Male bottlenose dolphins in stable alliances of 2-3 individuals form temporary consortships with individual females. Consortships often are established and maintained by aggressive herding. Consortships are associated with reproduction and are a useful measure of a female's attractiveness. Following reproduction, females may become attractive to males when their surviving calf is about 2-2.5 years old or within 1-2 weeks of losing an infant. Individual females are attractive to males for variable periods extending over a number of months, both within and outside of the main breeding season. The duration of attractive periods is greater during breeding season months than during the preceding months. Males sometimes are attracted to females for periods exceeding the reported duration of rising estrogen levels during the follicular stage of the oestrous cycle. Males occasionally have consorted or otherwise been attracted to females in several unusual contexts, including late pregnancy, the first two weeks after parturition, and the day after the loss of a nursing infant. Individual females were consorted by up to 13 males during the season they conceived, supporting predictions of a promiscuous mating system in bottlenose dolphins. Thus, consorting is a strategy by males to monopolize females, but not a completely successful one. Multiple cycling by female bottlenose dolphins may be a strategy to avoid being monopolized by particular males. Given the duration and agonistic nature of many consortships, the benefits to females of such a costly strategy are not obvious. Multiple cycling may reduce the risk of infanticide by males or allow females to mate with preferred males after being monopolized by less desirable males.
Impact of Embryonic Vocalizations On the Incubation Behaviour of Eared Grebes
Authors: Brua Robert B. 
Published: April 2008

AbstractTwo experiments were performed during the summers of 1991 and 1992 to determine whether embryonic vocalizations cause changes in the behaviour of adult eared grebes (Podiceps nigricollis) during late incubation. In Experiment 1, a vocalizing egg was substituted in 14 nests, two days before the first egg in that nest was to begin vocalizing. Parents reduced the amount of rising and resettling and the time spent off the nest while incubating and increased the frequency of egg turning, nest building, and percent of time the 'off-duty' parent spent near the nest. Only nest builds per h in the pre-peep period differed between the sexes in Experiment 1. For Experiment 2, the incubation period was extended by two days. At that time a vocalizing egg was substituted in 15 nests. Males reduced the amount of rising and resettling, whereas there was no difference between periods for females. Males and females reduced the amount of time spent off the nest while incubating. Egg turns per h, nest builds per h, and the percent time the off-duty parent spent near the nest increased for both sexes. No differences between males and females were detected except for egg turns per h during the peeping egg stage of Experiment 2. Parents also brought food to the nest in response to embryonic vocalizations. The behavioural changes by eared grebes during late incubation appear to be due to embryonic vocalizations. Several changes in behaviour are consistent with the care-soliciting hypothesis, such as reduction in exposure time of the embryo and possibly shortening of the incubation time of the embryo by an increased egg turning rate. Presenting food at the nest and possible acceptance of the young are further adaptive features of embryonic vocalizations.
Differences in Individual Learning Between Group-Foraging and Territorial Zenaida Doves
Authors: Carlier Pascal , Lefebvre Louis 
Published: April 2008

Abstract
Adaptive views of learning predict that natural selection should lead to differences in specialized learning abilities between animals that face different ecological pressures. Group-living is thought to favour social learning, but previous comparative work suggests that differences between gregarious feral pigeons (Columba livia) and territorial Zenaida doves (Zenaida aurita) exceed the specialized effect on social tasks predicted by the adaptive hypothesis. In this paper, we show that group-foraging Zenaida doves from Barbados learn an individual shaping task more quickly than territorial Zenaida doves from a site 9 km away. These results suggest that the scramble competition associated with group-foraging favours several types of leaming, both social and non-social, and that its effects are more wide-ranging than previously thought. Since genetic isolation between Zenaida dove populations is highly unlikely, the results also suggest that differences in foraging ecology may lead to different learned responses to local reward contingencies as well as natural selection for different genotypes affecting learning. In some cases, the standard comparative prediction of ecologically-correlated learning differences may therefore not distinguish between adaptive specialization and general process theories.
Models of Affiliative Relationships Among Free-Ranging Rhesus Monkeys (Macaca Mulatta)
Authors: Kapsalis Ellen , Berman Carol M. 
Published: April 2008

Abstract
Several organizing principles based on maternal kinship and/or dominance relationships, have been proposed to explain the structure of female-female macaque affiliative relationships. Social interactions among adult rhesus females of one free-ranging social group on Cayo Santiago, Puerto Rico were observed for four consecutive years to determine the extent to which patterns of affiliative interaction met several predictions of three such hypothesized organizing principles: kin-based attractiveness, attraction-to-high-rank and the similarity principle. We employed a multiple regression extension of the Mantel test (Smouse et al., 1986) to test the independent effects of kinship and rank distance on measures of affiliation and reciprocity. Close kin not only engaged in more affiliative behaviour than distant kin (see our companion paper, Kapsalis & Berman, this volume), they were more likely to support one another in agonistic encounters and to exchange grooming for alliance support and access to drinking water. We found evidence that low-ranking females were attracted to high-ranking females in some years of study, and that grooming by low-ranking females was exchanged with tolerance at a monopolizable resource by high-ranking grooming partners. However, we were unable to test conclusively for the effects of competitive exclusion. Little evidence was found to support the predictions of the similarity principle. We concluded that kin-based attractiveness was probably the primary organizing principle operating in the study group but that elements of attraction-to-high-rank may operate in concert to some extent.
The Effect of Substrate-Enriched and Substrate-Impoverished Housing Environments On the Diversity of Behaviour in Pigs
Authors: Haskell Marie , Wemelsfelder Françoise , Mendl Michael T. , Calvert Sheena , Lawrence Alistair B. 
Published: April 2008

Abstract
In intensive farming situations, growing animals are housed in relatively barren environments. The lack of opportunity to perform substrate-interactive and manipulative behaviour patterns may affect the expression and organization of these behaviours. However, making direct comparisons of the behaviour expressed in environments of differing physical complexity is difficult. In this experiment a relative diversity index was used to compare the behavioural repertoires of pigs housed in two different environments for a period of five months. One group of pigs (substrate-enriched) had straw, forest bark and branches added to the standard pens and the other group (substrate-impoverished) did not. The pigs were individually housed, and their behaviour was focal sampled in these pens on one day each month. It was shown that the relative diversity of manipulative behaviour shown by the pigs in the substrate-impoverished environment was lower than in the pigs in the substrate-enriched environment (p < 0.05). The relative diversity of the whole behavioural repertoire shown by the pigs in the substrate-impoverished environment also tended to be lower than that in the substrate-enriched environment (p = 0.06). It is concluded that this may be due to a difference between the two groups in motivation to interact with and manipulate objects, or a function of the manipulable quality of the substrates available to them. Alternatively, exposure to substrate-impoverished environments may interfere with the ability to express manipulative behaviour. Both situations pose a threat to the welfare of growing pigs resident in barren environments.