bluuebunny/crossref_metadata_2025 huggingface dataset:
Brood Division and Parental Care in the Period Between Fledging and Independence in the Dunnock (Prunella Modularis)
Authors: Byle Philip A.F.
Published: April 2008

1. Brood division was observed in 12 out of the 21 broods of dunnocks. It was stable over the whole period of fledging to independence. 2. Undivided broods were significantly more likely to occur earlier in the season than divided broods. 3. Brood size had no significant effect on the age at which chicks reached independence. 4. The weight (on day 6) of chicks in undivided broods influenced the age at which they reached independence, but no significant relationship was found in divided broods. 5. The provision of extra food significantly reduced the age at which fledglings reached independence, indicating that territory quality may affect the timing of independence. The effects of extra food on brood division were unclear. 6. There was no differential splitting of the brood between the dominant male and the female in polyandry and polygynandry or between a monogamous male and his female. Males and females fed the chicks at similar rates. 7. Beta males who had helped to feed the nestlings were more likely to continue to help feed fledglings in larger broods. 8. There was a tendency for male parents to care for male offspring and female parents to care for female offspring.
Reproductive Tactics of Male Savanna Baboons
Authors: NOË Ronald , Sluijter Albertha A.
Published: April 2008

The strongly related parameters rank, age and period-of-residence determine which reproductive tactics a savanna baboon male will use primarily. Baboon males go through the following phases with respect to the use of mating tactics, as they are longer in the group and thus grow older and, as a rule, drop in rank: Phase 1. Peripheral, relatively little social contact, low mating success, building up of a social bond with a few females. Phase 2. High mating success, based on individual fighting ability, social bonds mainly with females that are, or will soon be, sexually attractive. Phase 3, variant a. (Males that were very successful in Phase 2). Considerable time devoted to guarding infants conceived in phase 2 and to the mothers of those infants. Mating activity drops sharply compared to Phase 2. Phase 3, variant b. (Males that did not go through a very successful Phase 2). Low mating success through whatever tactic, relatively peripheral. Phase 4. Relatively high mating success, partly through collaboration with other males. Considerable time is invested in the care for potential offspring and their mothers. Phase 5. Diminishing share in the total mating activity in the group. The support for infants is spread over a relatively large class of infants conceived after immigration. Social contact with a large number of females. The data did not show the relation between agonistic rank and mating success predicted by ALTMANN'S priority-of-access model. A modification of the model is presented, which allows for coalition formation among males that are too low in rank to be successful on their own. This model could not fully explain, however, the exceptional success of some middle ranking males. The theory of Coalition games can give insight in the processes that lead to distributions of mating success that depart from the modified priority-of-acces model. The lack of agreement between the data and the original priority-of-access model cannot be explained by higher selectivity of the high ranking males. The only qualitative parameter of consorts obtained, according to which high ranking males had an advantage, is the time of the day on which mating activity takes place. This is a direct result of the way in which males obtain their consorts. Consorts are often formed in the sleeping trees during the night or in the early morning. In that situation single, strong males have an advantage in conflicts against coalitions of lower ranking males. Lower ranking males have a relative advantage later in the day, when conflicts are fought out on the ground.
Interventions in a Herd of Semi-Captive Plains Zebras
Authors: Schilder Matthijs B.H.
Published: April 2008

In a herd of semi-captive plains zebras interventions, which occurred within the harems, were investigated in order to answer the question why zebras interfered. These interventions are of interest because they regulate the contacts between companions and because, as corrective and preventive measures, they reveal the normative principles underlying the behaviours by which animals structure their social environment. An attempt was made to deduce 1) the internal norms of the interferer; 2) his short term aims; 3) his tactis and 4) his perception of the social environment. The analysis revealed that in the case of an affiliative interaction foals, yearlings and adult mares started to interfere if a friend had an affiliative contact with another zebra. In view of the interferer's behaviours it was concluded that their aim was to break off the ongoing interaction and that zebras tended to protect friendship bonds. Foals and yearlings further interfered if their mother was being threatened, attacked or sexually approached by a stallion. In view of the interferer's behaviours its aim was to prevent iminent interactions or to break off ongoing interactions. This suggests that these interventions were of a protective nature. The interferer's behaviours in both contexts ware very much alike. Mares tended to interfere if their foal/yearling or adult daughter was threathened or aggressed or if a mare friend was being sexually approached by a stallion. This type of intervention was of a protective nature. Stallions in a multi male harem showed a high tendency to interfere in courtship interactions. From the resemblance between interventions in courtship and in aggressive interactions it is concluded that, at leat in a number of cases, the individuals have perceived courtship behaviour by the stallion as a threat towards the mare involved.
Song Variability and the Response To Conspecific Song and To Song Models of Different Frequency Contents in Males of the Bushcricket Requena Verticalis (Orthoptera: Tettigoniidae)
Authors: Schatral Andrea , Bailey Winston J.
Published: April 2008

Variability in the temporal structure of the song has been investigated for the Australian bushcricket Requena verticalis (Listroscelidinae: Tettigoniinae: Orthoptera). Chirp interval and chirp duration of an individual male vary between two days. Males differ in their readiness to call. Sporadic singers sing consistently only in the presence of another calling conspecific or when acoustically stimulated, while steady singers call readily under acoustic isolation. Sporadic as well as steady singers change their chirp interval in the presence of another calling conspecific. Steady and sporadic singers are able to differentiate between 16 and 28 kHz, the two main frequency components of the song. There is evidence that the effect of the natural song on the temporal pattern of the call may be due to the 28 kHz frequency component. Individual variation in the temporal parameters is within 0.1 s, and the changes caused by acoustic stimulation are of similar magnitude. Further studies are necessary to evaluate if males and/or females uses these differences to discriminate between conspecifics.
The Functions of Song in Male House Wrens (Troglodytes Aedon)
Authors: Johnson L. Scott , Kermott L. Henry
Published: April 2008

To assess the functions of song in male house wrens (Troglodytes aedon), we examined the pattern of song output during different stages of the breeding cycle and behaviour patterns of focal males and conspecifics that were associated with song. We recorded 2093.5 bouts of song from 11 different males in 12 breeding cycles during 3 years. Most song sung prior to pairing is sung at a high volume and is given spontaneously (i.e. is apparently not produced in response to the behaviour of any conspecific). Production of high volume spontaneous song ceased immediately for at least 7 days when the male paired, but resumed immediately upon loss of the mate. Paired males sang high volume spontaneous song after mates began incubating, and almost always sang this song within 10 m of an unoccupied nest site. Several males attracted second mates to these nest sites and immediately ceased their output of high volume spontaneous song. These observations strongly suggest that high volume spontaneous song functions in mate attraction. Male house wrens do not appear to use song on a routine basis to communicate with neighbours or other males. However, they do appear to direct song at other males when territories are threatened. Song is sung at intruders in the territory and at neighbours just establishing a territory of their own. Most song sung after pairing appears to be directed towards mates. We suspect than males use song to inform mates that there is no immediate threat of predation, allowing mates to move quickly to and from nest sites. We discuss the role and benefits of descriptive, correlative studies in assessing song function.
Herd Structure, Leadership, Dominance and Site Attachment of the Camel, Camelus Dromedarius
Authors: Schulte Norbert , Klingel Hans
Published: April 2008

Social structure and relationships in a herd of captive camels were studied in Kenya. During day and night the herd split up irrespective of kinship. Partner preferences existed only in those camels who had previously been kept in a small group separated from the herd. Dominance relationships are anonymous with four levels: a) dominant breeding bulls, b) females and bachelors, c) subadults, and d) calves. No stable leadership was observed, but individual preferences in the walking order existed when the camels left and entered the enclosure. During the night most camels showed an amazing attachment to a particular resting site; in a new boma they used corresponding sites. During moon nights activity was greatly increased.
Stabilization of Sexual Preferences By Sexual Experience in Male Zebra Finches Taeniopygia Guttata Castanotis
Authors: Bischof Hans-Joachim , Clayton Nicky
Published: April 2008

Male zebra finches, Taeniopygia guttata castanotis, were normally-raised by zebra finches or were cross-fostered to Bengalese finch, Lonchura striata, foster-parents until 40 days of age. Following isolation until day 100, half the birds in each group were housed with a zebra finch female for seven days, isolated for three days and then housed with a Bengalese finch female for seven days. The other birds were exposed to females in the reverse order. Subsequent double-choice tests showed that all the normally-raised birds preferred zebra finch females whereas the preferences of cross-fostered males depended on the order of exposure to the two females: those exposed first to a Bengalese finch female preferred Bengalese finch females whereas of those exposed first to a zebra finch female, some preferred zebra finches, some preferred Bengalese finches and some showed no marked preference for either female. In order to examine the question of why the latter group showed such marked individual variation in their sexual preferences, a further group of males were cross-fostered to Bengalese finches and exposed to a zebra finch female and then to a Bengalese finch female and their behaviours were observed from day 21 until day 40 and for the two, seven-day periods with the females. The results show that, when comparing brothers within clutches, the one that begs and is fed more by by its foster-parents develops a stronger preference for Bengalese finch females and that the more song phrases a male directs to the zebra finch female during the first seven-day period, the stronger the sexual preference for zebra finch females in the double-choice tests. Hence, our results confirm and extend those of IMMELMANN et al. (1991) and KRUIJT & MEEUWISSEN (1991) that sexual imprinting may be a two step process. As a first step, information about the parents is learnt during a sensitive period early in life. In a second step, this information has to be tested for its validity for the selection of a sexual partner during first courtship encounters. It is this second step where the previously stored information is stabilized in memory. Giving conflicting information during the first and the second step, one can show that interactions between the young male and its parents as well as with its first sexual partner influence the final preference it shows in subsequent double choice tests.
Assessment of Patch Profitability and Ideal Free Distribution: the Significance of Sampling
Authors: Gotceitas Vytenis , Colgan Patrick
Published: April 2008

When allowed access to two food patches differing in food availability, groups of six adult, female, threespined sticklebacks (Gasterosteus aculeatus, L.) distributed themselves between patches according to the ratio of patch profitability, as predicted by the ideal free distribution (IFD) model. However, when individual fish were subsequently prevented from physically sampling patches differing in both food availability and the number of conspecifics present, patch choice did not conform to IFD. Instead, individuals preferred the patch with the greatest number of conspecifics present, regardless of potential foraging rewards. Preference for patches with the greatest number of conspecifics was, however, only evident when conspecifics were feeding. An outline of the decision process used by sticklebacks when selecting among food patches is presented.
Mutual Reciprocity of Grooming in Female Japanese Macaques (Macaca Fuscata)
Authors: Muroyama Yasuyuki
Published: April 2008

Grooming interactions among female Japanese macaques (Macaca fuscata) were observed and compared between affiliated and unaffilitated non-related pairs, mother and adult female offspring paris, and mother and immature offspring pairs. Unaffiliated (rarely interacting) members of pairs were likely to approach and then groom the other, in contrast to affiliated (frequently interacting) pairs, who more often approached and then solicited grooming from the other. The return receipt of a benefit just given, in the form of reciprocation of grooming, was immediate in non-related pairs. The brief interval between the occurrence of reciprocation facilitated the estimation of receiving as much benefit as was given in the case of rare grooming. However, such was not the case for related pairs. Adult female offspring solicited grooming from mothers more than immature offspring. The findings are discussed with reference to previous theories about the evolution of altruistic behaviour.
Response of Male Indigo and Lazuli Buntings and Their Hybrids To Song Playback in Allopatric and Sympatric Populations
Authors: Charles Baker Myron
Published: April 2008

The hybridizing semispecies indigo and lazuli buntings (Passerina cyanea, P. amoena) were studied in song playback experiments in allopatric and sympatric populations. In allopatry, males of both species responded strongly to conspecific and weakly to heterospecific songs. In sympatry, indigo, lazuli and hybrid males reacted equally and strongly to both indigo and lazuli songs. Alteration of song structures, by presenting indigo syllables in lazuli temporal pattern and lazuli syllables in indigo temporal pattern, showed that the response of allopatric indigo and lazuli males was determined primarily by syllabic (phonological) cues in the test songs and not by the temporal pattern. The overall pattern of male response in sympatry and allopatry provides some understanding of the observed degree of reproductive isolation between these species.
Mate Choice in Aidablennius Sphynx (Teleostei, Blenniidae); Females Prefer Nests Containing More Eggs
Authors: Kraak Sarah B.M. , Videler John J.
Published: April 2008

Criteria for female mate choice were investigated in a natural population of a Mediterranean blenny, Aidablennius sphynx. Removable test tubes in concrete blocks were offered as nests. Each tube was guarded by a male and females laid eggs in the tubes. Nests with larger broods received significantly more spawning females. The numbers of eggs laid increased with brood size from empty nests to intermediate brood sizes, but this tendency is reversed if nests contain very large broods. Nests with and without broods were exchanged experimentally among males. The number of eggs a male received, after an empty tube was replaced by a tube with eggs, was significantly higher. Conversely, the number of eggs received after a tube with eggs was replaced by an empty tube, was significantly lower. Male display did not increase the probability that females spawned. Male size did not correlate with the numbers of eggs received. It is discussed that female preference for large broods might be adaptive because the number of eggs present in the nest is probably a reliable predictor of the survival chances of the eggs.
Genèse De La Ségrégation Sexuelle Et Différences Comportementales Chez Des Enfants D'Age Préscolaire
Authors: Legault Frédéric , Strayer F.F.
Published: April 2008

La présente étude vise à clarifier le processus de la ségrégation sexuelle chez les jeunes enfants en relation avec l'émergence des différences sexuelles dans l'activité comportementale. Les interactions sociales de neuf groupes d'enfants comprenant 92 filles et garçons répartis en trois niveaux d'âge sont observées pendant plus de 130 heures, lors de périodes d'activités libres en garderie. L'inventaire comportemental comprend, après regroupements, sept catégories comportementales préalablement définies par STRAYER (1980). les analyses font ressortir un contexte de ségrégation initiée par les filles vers l'âge de deux ans. A trois ans, les garçons et les filles participent à ce processus. De plus, à partir d'une mesure du taux d'activité dirigé vers les cibles de chaque sexe, nous n'avons constaté aucun évitement actif de l'autre sexe mais plutôt une recherche qui croît avec l'âge de partenaires de son propre sexe. D'autre part, on remarque une plus grande activité en agonisme chez les garçons à partir de l'âge de deux ans. Ces résultats sont discutés à la lumière des principaux modèles explicatifs actuels des différences sexuelles.
Delayed Breeding in Avian Social Systems: the Role of Territory Quality and "Floater" Tactics
Authors: Zack Steve , Stutchbury Bridget J.
Published: April 2008

In many avian societies, young birds delay breeding beyond the age of sexual maturity. Most previous hypotheses of delayed breeding have emphasized forces that keep young birds from becoming breeders. We develop a model of delayed breeding which includes the future acquisition of a high quality territory as a potential direct benefit of delayed breeding. Strong differences in territory quality, age-correlated asymmetries in resource holding potential, and territory site tenacity set the stage for young birds to either breed immediately on a poor territory, or obtain a high quality territory through reproductive delay on or near the site. A wide variety of species and social organizations reveal common patterns of breeding status acquisition through behaviours as nonbreeders with site tenacity on or immediately near the breeding site. A review of 'floater' strategies reveals that nonbreeders frequently have restricted home ranges that encompass one or more breeding territories, and prior experience at a site improves their chances of acquiring a territory in future years. This pattern of territory acquisition argues for incorporating direct benefits into models of delayed breeding. We discuss the potential applications to understanding delayed breeding in social systems as apparently different as cooperatively-breeding birds, migratory passerines, colonial breeding gulls, and lek-breeding grouse and manakins.
Social Stability and Territory Acquisition in Birds
Authors: Beletsky Les D.
Published: April 2008

This study tested the hypothesis that one strategy birds use to acquire territories is to seek and exploit areas where conspecific social stability is weak. Predictions were that nonterritorial individuals, 'floaters', should be attracted to areas of social instability and that they should obtain territories in unstable areas. An experiment with red-winged blackbirds (Agelaius phoeniceus), designed to test whether floaters are attracted to boundary disputes between territorial neighbors, showed that floaters approached multiple male models in simulated boundary disputes at higher rates than they approached single models. Both drug implants that interfered with testosterone physiology in territory owners and manipulations of breeding habitat rendered certain territory aggregations socially unstable, and floaters obtained territories in those areas. Therefore, evidence generally supported the instability hypothesis of territory acquisition. No evidence was found to support an associated prediction, that a high-density breeding area should attract more floaters and thus suffer a higher territory owner turnover rate than a low-density site. Experiments with models of two species of blackbirds showed that one method floaters may use to establish territories is to settle on boundaries between adjacent owners. The potential generality of the instability hypothesis, and its implications for the expression of avian territorial behavior, are discussed. If floaters are attracted to signs of social instability, then it would be advantageous for territory owners to behave in ways that reduce the appearance of instability.
A Field Test of the Sound Environment Hypothesis of Conspecific Song Recognition in American Tree Sparrows (Spizella Arborea)
Authors: Naugler Christopher , Ratcliffe L.
Published: April 2008

The sound environment hypothesis predicts that the features of song that are important for conspecific recognition should be those that overlap least with the songs of other species in the same location. We tested this hypothesis with song playbacks to free-living male American tree sparrows (Spizella arborea). We first used a discriminant function analysis to determine which song features best separated American tree sparrow songs from the songs of heterospecific avian species at two locations representing different sound environments. Based on this analysis we predicted which song features should be most important for conspecific recognition at each location. We then produced synthetic songs containing alterations in these features. Males, however, did not respond to playbacks of altered features as predicted. Thus, our results do not support the sound environment hypothesis of conspecific song recognition.
The Pace of Life - Reanalysed: Why Does Walking Speed of Pedestrians Correlate With City Size?
Authors: Wirtz Peter , Ries Gregor
Published: April 2008

In a much quoted study, BORNSTEIN & BORNSTEIN (1976) showed that the walking speed of pedestrians is positively correlated with the size of the city. They interpreted the higher walking speed of people in larger cities as a psychological response to stimulatory overload. We also found a positive correlation between walking speed and city size. In addition, we showed that - at least in our sample - larger cities had higher proportions of young males and lower proportions of people older than 60 years. Walking speed and momentary density did not correlate positively. Because walking speed is age- and sex-dependent (Fig. 2), differences in population structure are likely to cause differences in average walking speed. The average walking speed predicted for each city according to its age- and sex-composition correlated positively with city size. The regressions of observed walking speed on population size and of walking speed predicted from age structure on population size did no differ significantly in their slopes (p > 0.95). It therefore seems unnecessary to invoke other factors in addition to age composition to explain differences in average walking speeds of pedestrians.
Behavioral Information Provided By Two Song Forms of the Eastern Kingbird, T. Tyrannus
Authors: Smith W. John , Smith Anne Marie
Published: April 2008

Eastern kingbirds facilitate prediction of their social behavior through the proportional use of two different song forms, zeer and chatter-zeer, in daytime singing performances. The chatter-zeer song form predicts approach to closer quarters, whereas zeer predicts a high probability of staying put. The correlations of each song form with behavior were determined by observing natural encounters singers had with their mates, conspecific intruders and birds of other species. Playback simulations of territorial intrusions were then used to test whether singers would approach with a high proportion of chatter-zeer and little or no zeer. This was strongly confirmed. Kingbirds who approach are taking a major interactional initiative, even though their next move is usually to await the other individual's response. In effect, singers dare or encourage those individuals to interact. The chatter-zeer with which they precede or announce approach does not specify the kind of interaction for which singers are prepared: the information it provides is as relevant in events in which the singer associates with its mate as in events in which the singer confronts an opponent. A zeer singer is less actively provocative, deferring initiative more while nonetheless being ready to respond to the actions of others. By providing information about the relative probabilities of these actions, singing should help kingbirds to negotiate or even arrange social issues while spatially separated, often obviating closer encounters. Since many kinds of animals sing, and since the characteristic continuity and cadencing of singing performances are specializations well suited to communicating at a distance, it is worth asking if other species also use singing patterns and songs to distinguish between the actions of holding back and approaching.
Individual Variation and Alternative Patterns of Foraging Movements in Recently-Emerged Brook Charr (Salvelinus Fontinalis)
Authors: Mclaughlin Robert L. , Grant James W.A. , Kramer Donald L.
Published: April 2008

Recently-emerged juvenile brook charr foraging in relatively homogeneous, clear, still-water pools displayed significant interindividual variation in the proportion of search time spent moving, the average speed during search, the average speed during periods of moving search, and the distance moved during pursuit of prey. The frequency distribution for interindividual variation in the proportion of time spent moving was bimodal, but distributions for the other movement parameters were not. Thus, in the field, young charr tended to specialize at one of two alternative movement patterns differing primarily in the proportion of time spent moving. The movement parameters were all positively correlated, but correlations between the proportion of time spent moving, the speed while moving, and pursuit distance were small enough (r2's < 0.30) to suggest that different aspects of search mode may vary relatively independently. Our findings have three implications for studies of search mode. First, intraspecific variation in search mode need not be only a response to environmental change, but can occur in the same environment at the same time. Second, frequency distributions of movement parameters offer a more objective base than do arbitrary classifications for determining how many types of foragers are present. Third, studies using different movement parameters to distinguish between alternative search modes (e.g. sitting-and-waiting and actively searching) may not be directly comparable.
Female Attraction Behaviour of Radio Tagged Polyterritorial Pied Flycatcher Males
Authors: Rätti Osmo , Siikamäki Pirkko
Published: April 2008

Polygynous mating is costly for pied flycatcher (Ficedula hypoleuca) females. Thus, females have a good reason to attempt to avoid mating with already mated polyterritorial males. One cue to disclose a male's mating status is his behaviour. The behaviour of polyterritorial and unmated males was studied by radio tagging that allows accurate recording of male movements. While attracting a secondary female polyterritorial males spent significantly less time on the secondary territory than did unmated males on their single territory. Polyterritorial males also tended to have lower song rates. When a female appeared on the secondary territory of polyterritorial males, they increased the proportion of time spent there, and as a result the difference between polyterritorial and unmated males was not significant. A female might potentially be able to estimate a male's mating status on basis of male presence at the territory, but only if she does not reveal herself. Still, the variation and overlap in male behaviour between mating categories may make it difficult for her to obtain reliable information about the mating status of a male.
Function of the Song and Song Repertoire in the European Starling (Sturnus Vulgaris) : an Aviary Experiment
Authors: Eens Marcel , Pinxten Rianne , Verheyen Rudolf Frans
Published: April 2008

We confronted individually-caged male European starlings, Sturnus vulgaris, with conspecifics of both sexes in order to study singing behaviour during intrasexual and intersexual encounters. Males spent more time at the nestbox, sang more songs and more song types during female presentations than during control periods (observation periods with no conspecifics). Males also sang more songs in the nestbox and flew more to the nestbox with green nest material. During male presentations, only the time spent at the nestbox and the carrying of nest material increased significantly. Males spent more time at the nestbox, sang more songs and more song types in response to a female stimulus than to a male stimulus. Males also sang more songs in the nestbox and flew more to the nestbox with nest material during female than during male presentations. These results suggest that the song and song repertoire of male starlings serve primarily an intersexual rather than an intrasexual function. However, in contrast to a previous study, our results suggest that singing also serves as an intrasexual signal to deter rivals at close encounter. We also tested the hypothesis that the 'whistles' and the 'warbling song' have separate intrasexual and intersexual functions, as has been suggested in the literature. We found no evidence for a specialized intrasexual function of the whistles nor for a specialized intersexual function of the warbling song. From this study it also appears that variations in the size of the aviary can modify the behavioural responses of starling males. New information with regard to the use of green nest material by male starlings is given.
The Breeding System of the Three-Spined Stickleback, Gasterosteus Aculeatus (Forma Leiura) With Reference To Spatial and Temporal Patterns of Nesting Activity
Authors: Mori Sechi
Published: April 2008

1) The breeding succes of three-spined stickleback (Gasterosteus aculeatus L., forma leiura) males in a small stream of the Tsuya River, Gifu Prefecture, Central Japan, was studied with reference to timing of nesting initiation, use of space for nesting and social interactions. The observations were made almost daily during March to early July 1988 along the shore at a distance of 1-2 m from the fish and nests. 2) All the males in an enclosed study pool were individually marked (99 males). Furthermore, a total of 67 females were marked and observed weekly. The males were individually observed and their agonistic, courtship and parental behaviour as well as their reproductive success were quantified. Reproductive success of individual male was measured as the number of nests built, the number of successful nests, the number of hatched fry per nest. Nest sites were categorized in six types (A-F) on the basis of the proportion of vegetation cover around the nest and distance from the shore. 3) Body size and environmental factors (water temperature, water depth, changes in water level) were not correlated with reproductive success. Flooding was not a major cause of unsuccessful nesting. The brightness of nuptial colouration at the onset of breeding correlated significantly with individual success. Individual variation in the development of secondary sexual characteristics such as a nuptial colouration may have an important consequence for the lifetime reproductive success of the individuals. There was no relationship between fish density and reproductive success. 4) All males that nested more than once had begun breeding early in the season. The sooner a male started nest-building, the more opportunities he had to complete breeding cycles. 5) After an unsuccessful nest, males were significantly more likely to move their nest sites than after a successful nest. The subsequent nesting cycle was not always successful. 6) There was variation in nest-sitc location. The spatial pattern of nest distribution was strongly related to the temporal pattern, because the first males which settled, more often built their nests at sites along the shore where the nest was covered on one or two sides by vegetation. The location of nest site was significantly correlated with reproductive success. When males nested in partly concealed places along the shore, they could sometimes obtain a high reproductive success irrespective of the date of breeding initiation. Thus, reproductive success was largely determined by the timing of nest-building and nest position.
Conflicting Demands in Sand Gobies: Predators Influence Reproductive Behaviour
Authors: Forsgren Elisabet , Magnhagen Carin
Published: April 2008

The effects of predation risk on the reproductive behaviour of male and female sand gobies, Pomatoschistus minutus, were investigated in two separate aquarium studies. In the presence of a predator (cod, Gadus morhua), males decreased their courtship activity while females did not alter their level of activity. In the second study, there was no difference between treatments (with and without predator) in the time from when a female was presented to a male with a nest until spawning took place or in the amount of eggs laid. However, pre-spawning behaviour differed between the two treatments. When the cod was in sight, both males and females burrowed in the sand more often. In the absence of a predator, pairs spent longer together in the nest before spawning started, and females also inspected the nest alone, which never happened during predator presence. Hence, both sexes make trade-offs between predator avoidance and behaviours associated with mating. Females, however, seem to take higher risks during the courtship phase in order to find a partner compared to males.
Sexual Imprinting in Zebra Finch Males: a Differential Effect of Successive and Simultaneous Experience With Two Colour Morphs
Authors: Vos Dave R. , Prijs Joop , TEN CATE Carel
Published: April 2008

Recent developments in theories of sexual imprinting have emphasized that sexual imprinting may lead to a preference for partners that are slightly different from the stimuli an animal has originally been exposed to. Two mechanisms have been proposed to account for this phenomenon. 1. Separate representation model: This model assumes that as a result of imprinting an internal representation is formed of each individual which a bird experiences during early life. The imprinting process is thought to reduce the responsiveness to novel individuals, whereas at the same time a habituation process would have the effect that individuals resembling these representations too closely are refuted. 2. Mixed representation model: Young birds combine information about different individuals into one internal representation. As a consequence the later preference deviates from the original imprinting stimuli. There is evidence that zebra finch males use a number of stimuli for sexual imprinting, but it is unclear whether and how the way of exposure affects the internal representation. This was examined in zebra finch males that had either successive or simultaneous experience with two different colour morphs of the zebra finch. Each type of experience results in different effects on later preference. Successive experience leads to a preference for both colour morphs. That is, in multiple-stimuli tests with the imprinting morphs and intermediate colour morphs, males with successive experience showed a preference for both imprinting morphs. Simultaneous experience with both morphs does not lead to a double preference but to a preference for the colour morph of the mother. Comparison with the control groups revealed that males raised by mixed pairs had learned to suppress sexual responses to individuals of their father's morph. This implies that zebra finch males learn to discriminate male versus female conspecifics on morphological features during the time course of sexual imprinting. The results of neither type of exposure gave evidence for the formation of mixed representations, as was indicated by the lack of sexual interest which double imprinted males showed for intermediates between both morphs. It is suggested that the way information is stored during imprinting can better be viewed within the context of distributed representation models.
Temporal and Acoustic Correlates in Vocal Exchange of Coo Calls in Japanese Macaques
Authors: Sugiura Hideki
Published: April 2008

Vocal exchanges of coo calls in female Japanese macaques were observed in two populations. Temporal patterns of occurrence of these vocalizations during vocal interaction were studied by analyzing inter-call intervals between two consecutive coos. When the second call was uttered by a different caller from the first (DC sequence), most of the second calls occurred at intervals shorter than approximately 0.8 sec, and the remaining ones at intervals longer than approximately 0.8 sec. These results indicate that the second coos of DC sequence are of two different types, and that second calls separated by short intervals may occur in response to the first call, whereas second calls separated by a relatively longer interval may occur independently of the preceding call. When an animal responds to a coo given by another, she appears to do so within a certain period of time. When two consecutiove calls were uttered by the same caller (SC sequence), the second coos rarely occurred within 0.8 sec, but mostly at longer intervals. These results suggest that when an animal utters a coo spontaneously, it remains silent for a short interval and when no response occurs, she is likely to give further coos addressing groups members. Acoustic analysis of two consecutive coos in DC sequence showed that the second coos given by a different caller and occurring within 0.8 sec significantly correlated with those of first coos with respect to several acoustic parameters. This correlation was not observed when coos occurred at intervals of more than 0.8 sec. This phenomenon was confirmed by a playback experiment. The results suggest the possibility that an animal is able to alter acoustic features of responding coos and matches those of preceding coos.
Temporal Patterns of Within-Pair Copulations, Male Mate-Guarding, and Extra-Pair Events in Eastern Red-Winged Blackbirds (Agelaius Phoeniceus)
Authors: Westneat David F.
Published: April 2008

I studied the timing of within-pair and extra-pair behaviors in an eastern population of red-winged blackbirds. Within-pair activity was highest several days before egg-laying started and during the morning and evening hours. Extra-pair events also peaked just before egg-laying but showed no distinct diurnal pattern. Red-winged blackbird pairs on average copulated 21-22 times per clutch. Males followed their females more than the reverse, but spent only a third of the time within 10 m of their mates. Male presence on the territory deterred potential extra-pair events, and although males were on their territories for 94% of their day, they did leave, apparently to forage, on occasion. Extra-pair events involving these males' females were more likely during these departures than expected by chance. Apparently as a consequence, males went on fewer forays when their female was most fertilizable. Males did not copulate with their females more often than normal just before or after forays or intrusions. Pairs that copulated more often had fewer extra-pair fertilizations in their broods, but no other behaviors were correlated with paternity. These results have several important implications for understanding the effects of sperm competition of mating and parental behavior.
Stimuli Eliciting Distress Calls in Adult Passerines and Response of Predators and Birds To Their Broadcast
Authors: Conover Michael R.
Published: April 2008

This study examined the response of birds and captive predators to the broadcast of distress calls and the effect of different stimuli on the elicitation ofthese calls. In doing so, this study tested two hypotheses about why adult passerines should distress call when physically constrained: the calls are designed 1) to attract attention, or 2) to startle the predator into releasing the caller. Birds often responded to both interspecific and intraspecific distress calls by approaching the sound source, but they rarely mobbed or engaged in any behavior that would aid the caller in escaping. The playback of a distress call had little effect on most captive opossums (Didelphis marsupialis) and raccoons (Procyon lotor) which were attacking a caged starling (Slurnus vulgaris). However, distress calls startled one opossum and two raccoons and provoked two other raccoons into a more severe attack. Birds only distress called when physically constrained. All passerine species that were tested, except brown-headed cowbirds (Molothrus ater), emitted distress calls, but in no species did every individual call. Distress calls usually were of short duration, interrupted by periods of silence, and paired with struggling behavior. Birds were more likely to distress call when held by the limbs rather than the body or neck, when moved, or when viewing a rapidly approaching object. These results indicate that one function of distress calls for most passerines is to startle the predator, but that other functions also are likely. My results also support the hypothesis that birds approach a distress caller to acquire information about the predator that has captured the caller.
Mother-Infant Relationships in Three Species of Macaques (Macaca Mulatta, M. Nemestrina, M. Arctoides). Ii. the Social Environment
Authors: Maestripieri Dario
Published: April 2008

This study compared social interactions between mothers, infants, and other group members in rhesus, pigtail, and stumptail macaques living in large captive social groups. Mother-infant pairs were focally observed in 4 weekly 30-min sessions for the first 12 weeks of infant life. Rhesus and pigtail mothers were remarkably similar in several contact, proximity, and grooming measures, but their scores were lower than those of stumptail mothers. The three species did not differ quantitatively in interest shown in infants by other group members, as measured by infant handling and grooming. Infant handling in stumptail macaques was always gentle and infants were carefully avoided by other group members when off their mothers. Infant handling in rhesus and pigtail macaques also involved harassment and kidnapping. The frequency of infant harassment did not differ in rhesus and pigtail macaques but harassment was more severe in the former than in the latter species. Rhesus mothers reacted aggressively to a higher proportion of infant handling attempts than pigtail and stumptail mothers. These results confirm the hypotheses that female interest in infants does not differ among macaque species and that the quality of infant handling is a good predictor of interspecies differences in maternal protectiveness. Mothering style, however, is probably multidimensionally determined, and to fully understand interspecies differences in mother-infant relationships and their functional significance, we need to understand the mechanisms by which reproductive and ecological variables influence maternal behavior and infant development in primates.
Dawn Singing in the Great Tit (Parus Major): Mate Attraction, Mate Guarding, or Territorial Defence?
Authors: Slagsvold Tore , Dale Svein , SÆTRE Glenn-Peter
Published: April 2008

In a number of passerine bird species, mated males sing at dawn and this song activity peaks in the fertile period of the mate. We present the hypothesis that an important function of such dawn singing is to maintain the territory. We suggest that mate guarding and territorial defence are demanding and often mutually exclusive activities. Losing paternity is so costly that males give priority to mate guarding. Males therefore use the early morning period, before their mate emerges from the roost, to claim territory ownership. We report some preliminary tests of this hypothesis from a study of great tits (Parus major). Simulating male intrusion by a playback experiment showed that the resident male was more often absent from central parts of the territory, following the mate, during the periods of nest building and egg laying than during incubation. This supports the assumption of conflicting demands between mate following and territorial defence. From the hypothesis we expected males to spend effort in defending their territory as soon as they were free to do so. Consistent with this prediction, we found that male song activity was high before the mate left the nest at dawn, when she temporarily visited the nest during the day, and when she entered the nest to roost at night. A female removal experiment showed that unmated males, having no mate to guard, sang as much at dawn as mated males. Only one of the eight widowed males succeeded to replace their mate. We discuss some alternative functions of dawn singing in the great tit, such as attraction of own mate, a replacement mate, and extra-pair mates. We conclude that the hypotheses are not mutually exclusive, and song may serve multiple purposes.
Brotherhoods Among Atelins: Kinship, Affiliation, and Competition
Authors: Strier Karen B.
Published: April 2008

This paper examines differences in male affiliative associations and dominance relationships in atelin primates. Despite the occurrence of male philopatry in all three genera, male social relations varied considerably. The strength of male affiliations was attributed to differences in between group competition for access to groups of females, while the type of male dominance relationships was attributed to differences in within group competition for access to individual females. Female grouping patterns and the socionomic sex ratio appeared to be more important than group size in predicting the strength of between group competition and male affiliations. Male dominance over females appeared to be more important than estrus synchrony in predicting the type of within group competition and the presence of hierarchical or egalitarian relationships among males.
Flock Size and Foraging Decisions in Central Place Foraging White Storks, Ciconia Ciconia
Authors: Alonso Javier A. , Alonso Juan C. , Carrascal Luis M. , Muñoz-Pulido Rodrigo
Published: April 2008

We studied the foraging decisions of six individually marked white storks at a breeding colony in central Spain. Storks behaved as central place foragers, gathering in flocks to feed. Travel distance and patch residence time were positively correlated with the size of the foraging flock, but not with patch quality as estimated by the instantaneous food intake rate at the patch. Patch residence time was also positively correlated with travel distance to the patch, flock size being constant. In larger flocks individuals benefitted from a decrease in vigilance time and thus an increase in time spent actively feeding, which enabled birds to bring back to the nest a higher load size. These results suggest that storks followed simple rules of thumb based on flock size, rather than on the more complicated food availability estimations required by central place foraging models. We suggest that flock size could be the main cue used in foraging decisions by white storks and could be a simple rule for many other flock foraging species.