bluuebunny/crossref_metadata_2025 huggingface dataset:
Aggressive Communication By Larus Gla Ucescens Part Ii. Visual Communication
Authors: Stout John F. , Brass Melvin E.
Published: April 2008

Pairs of complete models or wooden block models with adjustable stuffed heads of Larus glaucescens were placed in gull territories. Choice of attack on the models revealed that the head and neck of L. glaucescens are the parts of the body that release aggressive display in territorial behavior. When using models with the head and neck mounted in a normal posture, the upright threat model received a significantly greater number of attacks than the oblique model. The oblique model received a significantly greater number of attacks than the choking model. When comparing the reactions caused by the abnormal postured head at levels identical to those of the normal aggressive postures upright threat, oblique and choking, there were similar results. It was apparent that visual communication was accomplished by head level. A higher head level portrayed lower level of aggressiveness, whereas a lower head level portrayed greater level of aggressiveness and inhibited attack on the model. Secondary aggressive stimuli, such as squinted eyes and muscle tension, are probably not significant in evoking or prohibiting an attack.
Vocalizations Elicited By Electrical Brain Stimulation in Coturnix Coturnix Japonica
Authors: Potash Lawrence M.
Published: April 2008

1. Most of the natural calls emitted by adult Japanese quail in the breeding phase of their life cycle could be placed into 15 categories. Brain-stimulation elicited vocalizations resembled examples of 10 of the 15 call categories.
Patterns of Inheritance in the Bowing Display and Associated Behaviour of Some Hybrid Streptopelia Doves
Authors: Davies S.J.J.F.
Published: April 2008

The bowing display of Streptopelia doves was studied in captive individuals of five species at Madingley, Cambridge, England from 1961 to 1964. The five species were S. roseogrisea-(risoria) (barbary), S. decaocto (collared), S. turtur (turtle), S. chinensis (necklace) and S. senegalensis (senegal). F1 hybrids were bred between the barbary and the other four species and single males of each of the F1 necklace x collared and senegal x turtle were also observed. F2 generation birds of the collared x barbary F1 hybrid, as well as some backcrossed birds were included in the study. Bowing displays were usually given only by male doves when close to another dove. The form of the bowing display differed from species to species and exhibited a typical intensity in each species. Each hybrid also had a bowing display of characteristic form. The ciné film showed that there was variation in form between the bowing cycles of any one bout, both in the pure species and in the hybrids. This variation could not be adequately described from the films taken in this study. The rate of bowing of each species was constant and differed from that of every other species. Hybrids also exhibited a typical intensity in this character. There was much more intra-specific and intra-hybrid variaton in the timing of individual movements within bowing cycles in a bout than in the timing of the bowing cycle as a whole. The relative variability of the different elements could be ranked, and in all species and hybrids studied the timing of the total cycle tended to be least variable and that of the pause at the top of the bow most variable. The frequencies with which bowing displays and kah calls were given under standard conditions, were measured, and provided two other behavioural characters whose pattern of inheritance could be studied. Three patterns of inheritance were found in each of these behaviour patterns of the F1 hybrids. In some cases the behaviour was intermediate between that of the two parents, in others it approximated the behaviour of one parent closely and in others again the hybrid's behaviour exceeded the range of either parent.
Classification of Social Signals in Squirrel Monkeys By Means of Cluster Analysis
Authors: Maurus M. , Pruscha H.
Published: April 2008

It is the chief aim of this project to reduce the extremely large number of observable actions of squirrel monkeys to a smaller number of classes of actions, which can be distinguished from each other in respect to their function in the communication processes of the animals. By means of such a classification, we want to increase the predictability of successive social signals. Using an agglomerative cluster method - in which the quantity trans information taken from information theory is responsible for the formation of the classes - such a classification based on two kinds of frequency matrices is found. That we actually obtain classes of actions having the same or at least similar meanings, is proven not only by way of the results derived from cluster-analysis, but also from an explicit study of the frequency matrices on which they are based. The biological relevance of the classifications we have found as well as the mathematical methods we have used is discussed.
Behaviour of Red Deer (Cervus Elaphus L.) At Calving Time
Authors: Clutton-Brock T.H. , Guinness F.E.
Published: April 2008

Red deer on the Isle of Rhum (Inner Hebrides) show a well defined calving peak in late May and early June. Just before calving, hinds leave their usual social groups and move away from areas of high population density. Calves spend most of the day lying away from their mothers and are visited at intervals. During these visits, mothers show increased vigilance and flight distance from observers. When disturbed close to their lying calves, hinds are unwilling to approach the calf's position and may move the calf to a new area during the following 24 hours. Calves select their lying position with care, preferring to lie in long vegetation in places where they are sheltered from sight and can see the ground in front of them. All these behaviour patterns change during the first four weeks after parturition. The behaviour of hinds breeding for the first time differs little from that of experienced mothers.
The Relation of Scent-Marking, Olfactory Investigation, and Specific Postures in the Isolation-Induced Fighting of Rats
Authors: Adams David B.
Published: April 2008

The temporal sequences of acts and postures of rats during tests for isolation-induced fighting were recorded and analyzed. Scent-marking and olfactory investigation, which have been related to fighting by previous studies, were particularly emphasized. From the data a model was constructed for the sequence of behaviors which lead to and maintain isolation-induced fighting. The typical sequence begins with olfactory investigation and scent-marking; the home rat initially investigates the intruder, and the intruder initially investigates the cage. The combination of olfactory perception of a strange male and a familiar environment, it was suggested, serves to trigger an offensive mechanism in the home rat which leads to bite-and-kick attack and offensive sideways posture. The pain of the attack then triggers defensive mechanism in the intruder rat which leads to defensive upright posture and submissive posture. Whereas the functional role of the bite-and-kick attack appears to be simply the infliction of pain and elicitation of defense in the intruder, the function of offensive sideways posture as a threat behavior may be more complex. It is possible that it becomes a conditioned pain stimulus due to its close temporal pairing with bite-and-kick attack, but it is more likely that it produces defense by a process of sensitization. In any case, following the initial attack, the offensive sideways posture continues to elicit defensive behavior by the intruder even when there are no further attacks. The functional roles of the defensive postures were interpreted as positioning the intruder in such a way that the home rat cannot assume the aggressive posture from which attack is launched. Scent-marking behavior was consistent within strains, within individuals, and across different types of measures (accumulation of scent-marking marking material and performance of the stereotyped scent-marking act, crawl-over-dish). Amount of scent-marking was not correlated with attack, however, and its role in isolation-induced fighting remains unclear. In parallel to findings in other rodents, it was observed that scent-marking was diminished in animals after they had been subjected to attack.
Status Signaling in Harris Sparrows: Some Experiments in Deception
Authors: Rohwer Sievert
Published: April 2008

(1) Harris Sparrows signal their social dominance status by variations in the amount of black feathering on their crowns and throat. The potential ability of individuals to cheat on such a status signaling system was experimentally investigated by dyeing and bleaching some free-ranging individuals in a flock attracted to a bait station. As discussed in detail, cheating is a theoretically important problem because survival studies have shown subordinates to be much less likely to survive over winter than dominants. If true, this should result in strong directional selection toward the dominant plumage type. (2) Subordinates dyed to mimic the highest ranking birds of the winter hierarchy were, with but one exception, persecuted by the legitimate studlies. The single exception was apparently a bird which had underestimated his status during the fall molt when the appropriate plumage signal is produced. (3) Bleached birds were forced to fight much more for their status, as dramati. cally shown by what was likely the first encounter between a bleached bird and a normal individual of just slightly lower rank. Eventually the bleached birds behaved as though all others around them were perceived as disrespectful, and despotically attacked birds at an abnormally high rate. (4) While these data strongly suggest that cheating is socially controlled, such a social organization raises some complex evolutionary issues. An alternative explanation of the apparent social control of cheating is that the unusual behavior observed in response to my manipulations merely represented normal defense of winter resources. This explanation requires that the rate of winter dominance inter-actions be controlled by (1) the risk of attack, and (2) the importance of resource defense. If this is true, the dyed birds may have appeared sick since no hormonal manipulation accompanied their dyeing; thus they may have been attacked more because perceived risk was down and potential gain high (beat the toughy while he is down). Likewise, the bleached birds may have become unusually aggressive because the closer approach of low ranked birds suggested to them that a much more active defense of resources was required. Experiments distinguishing these hypothesis have not yet been performed.
Group Organization of a Territorial Damselfish, Eupomacentrus Planifrons
Authors: Murray Itzkowitz
Published: April 2008

1. El "damselfish" Eupornacentrus planifrons tiene densas poblaciones territoriales en el coral de "staghorn" (Acropora cervicornis). 2. Las inspecciones del campo y los experimentos del campo manifestaron que los individuos preferían mantenerse en un territorio inferior dentro de un grupo grande, más bien que estar solos en una habitación sobresaliente. 3. Los individuos que ocupaban posiciones inferiores dentro del grupo muchas veces divagaban alrededor de la colonia del coral (corrías) en busca de vacancias dentro de habitaciones de primera clase. 4. El tamaño del "damselfish" tuvo correlación con la calidad de la habitación y se encontraron individuos más grandes en las áreas mejores de la colonia de "staghorn". Todas las veces que los habitantes salían de las áreas, los territorios eran poblados por otros individuos que tenían un tamaño semejante como el de los ocupadores anteriores y de los individuos vecinos. 5. Puesto que los machos, tan bien como las hembras, mantenían territorios dentro de una colonia, en las colonias más grandes los individuos podían encontrar con más facilidad a potenciales machos o hembras. Esta hipótesis es verificada por las observaciones siguientes: los individuos no viajaron mucho fuera de las fronteras de sus colonias y la mayoría del noviazgo occurió en las colonias mas grandes. 6. Se tratan las semejanzas entre las estables colonias territoriales y los sistemas jenárquicos.
Selection and Dropping of Whelks By Northwestern Crows
Authors: Zach Reto
Published: April 2008

Prey selection, dropping behaviour and dropping site selection was investigated in Northwestern crows (Corvus caurinus) feeding on whelks (Thais lamellosa). Crows selected only the largest whelks available in the intertidal zone. Although equally palatable, smaller whelks were ignored. Crows assessed size of whelks first by sight and then by weight. Thus, some were picked up with the bill and laid down again before a final selection was made. Rejects were longer and heavier than available whelks and shorter and lighter than selected ones. Usually, crows carried and dropped only one whelk at a time. While dropping, crows typically flew almost vertically up, released the whelk and then dove after it. The mean number of drops required to break a whelk was 4.36. Crows dropped whelks until they could obtain most or all of the soft parts. Usually crows did not give up dropping a whelk until it broke. The mean height of drop was 5.23 m. Crows had a tendency to increase height of drop over successive attempts. During most flights, crows lost some height before releasing a whelk. Presumably, this allowed them to watch whelks fall and bounce. All whelks were dropped onto rock. None were released over water or grass. Crows had specific dropping sites. This was because they selected hard substrate and safe sites for dropping. On dropping sites whelks were unlikely to bounce into water. Results were compared with those of other studies of dropping behaviour in gulls and hawks. Dropping behaviour in crows seems to be much more adaptable than in gulls.
Territorial Behavior of a Blackbird: Mechanisms of Site-Dependent Dominance
Authors: Haven Wiley R. , Wiley Minna S.
Published: April 2008

The behavioral mechanisms that produce territoriality require that a resident's agonistic tendencies vary with the locations of encounters with opponents or with the distance between the resident and an opponent. Variation in agonistic tendencies with location could result from increased aggressiveness in familiar locations. Only a few field studies have previously documented variation in aggressive tendencies either with the location of an encounter or the distance of an opponent. In this study, we measured the spatial distributions of advertising activities in the territories of male yellow-hooded blackbirds Agelaius icterocephalus and related these distributions to aggressive tendencies of the residents. Advertising and agonistic activities resembled those of other marsh-nesting blackbirds in the genera Agelaius and Xanthocephalus. To portray the spatial distributions of activities, we determined convex hulls for the 95 % and 68% of instances or seconds of an activity closest to the vector mean of the distribution. A territorial male's time perched conspicuously, instances of conspicuous perching, songs and song flights were concentrated near the center of his territory. In spite of this uneven distribution of a male's time and advertising activities within his territory, a male's aggressive tendencies toward intruders did not vary clearly either with the intruder's location or distance from the resident, provided only that the intruder was within the resident's boundaries. Interactions with neighbors suggested that use of an area is a prerequisite for its defense. Changes in boundaries and establishment of new territories revealed that a male's use of an area increased before aggression toward neighboring residents began. Changes in a resident's territorial boundaries often resulted from changes in the spatial distribution of residents' activities as a result of localizing activities around nests of egg-laying females or changes in the locations of nests under construction. These observations suggest that predominance in use of an area leads to dominance in defense of that area.
Variations in the Structure of Bleats From Sheep of Four Different Breeds
Authors: Shillito Walser Elizabeth , Hague Peter
Published: April 2008

Characteristics of bleats from groups of ewes from Clun Forest, Dalesbred, Jacob and Border Leicester breeds are described. The bleats were analysed on a sonagraph and measured for length, fundamental frequency and formant structure. The bleats from Border Leicester sheep differed most from the other breeds, they were the longest bleats and had the lowest fundamental frequency with four formants in a pattern 4-10-14-17. Clun Forest ewes had the shortest bleats and highest fundamental frequency, with three formants in a pattern 3.6-8-12. Jacob bleats showed little variation in fundamental frequency and were lower than Dalesbred and Clun bleats. They sounded rich and mellow and often had only two formants in a pattern of 4-9 (sometimes 12). Dalesbred bleats were long and vigorous with well marked harmonics. Their formant pattern was 4-9-13. Individual ewe's bleats had a combination of characteristics which were different from bleats of other sheep. Lambs do not seem to use any one particular character of the bleat to identify the voice of their dam.
Helpers(?) At the Nest in the Mongolian Gerbil, Meriones Unguiculatus
Authors: Ostermeyer Malcolm C. , Elwood Robert W.
Published: April 2008

Mongolian gerbil families were observed in artificial burrow systems and the effects of the presence of juveniles and the number of 'underground' nest areas were noted. Juveniles interacted with infants and increased their time in the maternal nest during the rearing of the infants as did the fathers. Parents spent less time self-grooming and licking the infants if juveniles were present. The fathers appeared to act paternally mainly towards the juveniles but also supplied the "underground" area with food. These observations were congruent with the prediction that juveniles act as helpers at the nest. A second experiment, however, indicated that juveniles retarded the development of the infants, possibly by stealing milk. The parents appeared to minimise the detrimental effects that juveniles had on the development of the infants and yet ensured that the juveniles remain within the family group until they were old enough to fend for themselves. The number of nest areas had little effect on these social interactions.
Observations On Vocalization of Ewes and Lambs in the Field
Authors: Shillito Walser Elizabeth , Walters Eurof , Ellison Judy
Published: April 2008

Dalesbred, Jacob and Soay ewes were observed with their lambs in the field for 3 months, to record when vocalizations occurred and the subsequent behavioural interactions. Soay ewes bleated and moved towards their lambs more than the Dalesbred and Jacob ewes, and were the least vocal in response to the lamb's bleats. The Soay lambs had the lowest proportion of vocal responses without movement to the ewe's bleats, but were more likely to bleat themselves and run to their dam, than the Dalesbred and Jacob lambs. They also had a low proportion of results in the category 'No response'. Dalesbred ewes bleated in reply to their lamb's bleats without moving toward the lambs, more than the other breeds. The Dalesbred lambs bleated and ran to the ewes in response to the ewe bleats more than the Jacob and Soay lambs, and the proportion of this response increased with age. The Jacob ewes and lambs had the highest incidence of 'no response' recorded to their vocalization. These results are discussed in relation to experimental findings on vocalizations in sheep, and it is suggested that domestication has tended to increase the amount of bleating by sheep.
Feeding Behaviour of Three Species of Squirrels
Authors: Ando Motokazu , Shiraishi Satoshi , Uchida Teru Aki
Published: April 2008

The Japanese giant flying squirrel, Petaurista leucogenys, Japanese flying squirrel, Pteromys momonga and Asiatic chipmunk, were compared for feeding behaviour under experimental conditions. Although P. leucogenys always fed in a sitting posture on branches, it extended its forepaws effectively both laterally and ventrally. When the animal was not able to place its large body on a slender twig, it brought the twig within reach of the mouth by the forepaws, obtaining food at the tip. P. momonga and T. s. asiaticus took a hanging posture, too, and the former was more skillful in this posture than was the latter. In picking up food scattered on the floor, P. leucogenys extended the body, without shifting its hindfeet, in a wide range including its lateral side; T. s. asiaticus got food in a narrow range only just in front of the body, and P. momonga had an intermediate range between those of the above two species. Among the three species, the daily frequency of feeding bouts was in inverse proportion to the duration of a feeding bout; P. leucogenys had relatively long and infrequent bouts, the reverse being the case with T. s. asiaticus. Characteristics of the posture, technique and frequency of feeding in the three species were supposed to be a reflection of interspecific differences in the diet, habitat, and freedom and length of the forelimb.
Sensory Factors Involved in Immediately Postnatal Ewe/Lamb Bonding
Authors: Vince M.A. , Lynch J.J. , Mottershead B. , Green G. , Elwin R.
Published: April 2008

1. Aspects of the ewe which influence the lamb. Lambs were removed from their mothers at birth and tested under one of seven conditions : (1) with the dam in her pen, or, in a circular arena, (2) in the presence of a stationary model ewe, (3) with the same model, but moving, (4) in the presence of a large, headless and legless moving object, (5) with stimulation by the sound of recorded bleats, (6) with tactile stimulation or (7) with no stimulation. Indices of responsiveness included movements of righting and standing, approach to the model, bleating and nosing of the model or the arena. Results showed that lambs tested with the stationary model stood most slowly whereas the presence of the moving model ewe was associated with rapid standing. The groups with no experimental stimulation at all, or with stimulation by the sound of recorded bleats, also stood rapidly. Bleating of the lambs was most prevalent in the group with no stimulation at all. Lambs presented with moving models approached them more rapidly and nosed them more than did those tested with the stationary model. More than any others, lambs in the "stationary model" group were quiescent for long periods. Lambs tested in the presence of their mothers and those given tactile stimulation were consistently low in the rank order for all indices of response; in particular they stood more slowly and bleated less than groups presented with moving models. It is concluded that the dam is a composite stimulus for her lamb; she activates it when she moves but also elicits responses which reduce its early activity. 2. Aspects of the lamb which attract the ewe. Ninety Merino ewes, from each of which the lamb had been removed at birth, were tested in their own pens under one of the following conditions: (i) with their own lambs; (ii) with a warm, moving lamb model soaked in amniotic fluid and accompanied by lamb bleats, or with the same model but (iii) without movement; (iv) without warmth; (v) without bleats or (vi) without amniotic fluid. A seventh group was tested with a white bowl of warm amniotic fluid, also moving and accompanied by lamb bleats. The ewes approached their own lambs and were much more attentive to them, than to any of the models. The model which received the least attention was that (vi) with no amniotic fluid, while the 'model' which received the most was (vii) the white bowl containing amniotic fluid.
Interspecific Aggression By Barrow's Goldeneye: a Descriptive and Functional Analysis
Authors: Savard JEAN-PIERRE L. , Smith James N.M.
Published: April 2008

We describe interspecific aggression and territoriality by a diving duck, the Barrow's goldeneye. Males of this species are strongly interspecifically territorial early during the breeding season, and in winter. Females are interspecifically territorial while tending broods of ducklings. Aggression was strongest against conspecifics, and against the con-generic bufflehead, which shares the same breeding habitat. Other diving ducks, which overlap in diet with goldeneyes, were frequently attacked, while dabbling ducks, with differing feeding habits, were generally tolerated, and were seldom attacked. One dabbling duck, the blue-winged teal, in which the drake resembles the Barrow's goldeneye drake in plumage, was attacked more strongly than other dabblers. We propose that the strong interspecific aggressiveness exhibited by the Barrow's goldeneye, and its congeners the bufflehead and common goldeneye, is a consequence of the strong intraspecific aggressiveness of these species. Selectivity in aggression towards victims of different species can be explained by two hypotheses. Species that have (1) similar diets, and (2) similar plumages to Barrow's goldeneye are selectively attacked.
Mobbing Behaviour, Nest Exposure, and Breeding Success in the American Robin
Authors: Mclean Ian G. , Smith James N.M. , Stewart K. Glenna
Published: April 2008

We tested some costs and benefits associated with variable levels of mobbing response towards nest predators by American robins. Playbacks of robin mobbing calls attracted a major predator of robin nests, the northwestern crow. This demonstrates a potential cost to robins that give mobbing calls. We then used human 'predators' to test whether reproductive success was related to mobbing intensity. We first showed that mobbing responses to humans resembled those shown to a stuffed crow. Second, we demonstrated that responses of pairs of robins were consistent at different tests at the same nest, but were less consistent between different nesting attempts of the same pair. The first result validates our experimental procedure, but the second result suggests that variation in mobbing response is partly determined by characteristics of the nest or nest site, rather than by the level of aggressiveness of the parents. When we compared mobbing responses by robins at exposed and well-concealed nests, robins with exposed nests used extreme responses (swoops and hits) more frequently than those with concealed nests. We did not, however, find an consistent relationship between mobbing intensity, stage of the nestling cycle, or reproductive success. Robins did not respond more strongly late in the nesting cycle, and pairs that responded weakly, or strongly, experienced similar levels of nesting success.
Song Structure and Singing Strategies in the Genus Luscinia in Different Habitats and Geographical Areas
Authors: Sorjonen Jorma
Published: April 2008

The structure of song and song propagation of studied populations of the Finnish thrush nightingale, the Mediterranean nightingale and the bluethroat (L. svecica) are in accordance with the prediction that birds living in less open habitat and usually singing inside the forest canopy, use more whistles and modulated elements and less trilled syllables (especially fast trills) in their songs than the species in more open habitats. However, the effects of the geographical location and other species in song communities are greater than that of habitat. The birds also seem to be able to improve their long distance communication easier by change in singing behaviour than by change in song-structure. The thrush nightingale males in the northern population improved detectability of their song by singing at midnight when most other species in the bird community are silent. At the same time the males increased song length and decreased intersong pauses, which increased their total vocalizing time and improved the receivers' possibility to detect their acoustic information. This strategy presumably improves rapid pair formation, which is important for long distance migrants in the northern latitudes with short favorable season for breeding and subsequent moulting.
Partner Attack Inhibition in the Convict Cichlid, Cichlasoma (Archocentrus) Nigrofasciatum
Authors: Turner George F.
Published: April 2008

The paper investigates the occurrence of submission in relation to the courtship of the biparental sexually dimorphic convict cichlid, Cichlasoma (Archocentrus) nigrofasciatum. It was found that submission by females was not necessary for courtship to proceed and such behaviour was found only in a similar context to fleeing behaviour. The presence of an intruding male, while generally invoking courtship activities, did not reduce the aggressiveness of a resident female towards other conspecifics. Thus any inhibition of aggression was specific to the potential mate only. Similarly intruding males did not attack aggressive resident females, even though no symbolic inferiority was performed. It is suggested that inhibition of aggression towards the partner can occur in the absence of symbolic inferiority and proposed that a new terminology be adopted. Particular activities involved should be named according to postural elements, and the functional category referred to as Partner Attack Inhibition (PAI).
Tactile Communication Between Ewe and Lamb and the Onset of Suckling
Authors: Vince Margaret A.
Published: April 2008

A series of experiments shows (1) that the effects of tactile stimulation produced by covering the face and eyes of an unsuckled Clun Forest or Soay lamb elicits a vigorous response which includes elements such as tilting up of the muzzle, lengthening of the neck, munching, mouth opening, curling back of the upper lip in the sucking position, tongue protrusion and apparent reaching and grasping movements of the lower jaw, upper and lower lips and the tongue (2) that these movements are directional in that the neck, head, lower jaw, lips and tongue are usually turned towards the stimulus (3) that before the lamb has attained a standing posture this response appears only weakly and may be replaced by a downward head movement; also it is weakened or disappears after the lamb has sucked (4) a similar response can be elicited by a visual stimulus only more slowly and in a less vigorous form. In Soay, but not in Clun Forest, lambs the response to touch was maintained for longer when the eyes were covered, than when the lambs were able to see (5) touch on the belly of the dam, simulating that produced by a lamb pushing its muzzle up against her, causes her to arch her back upwards, while touch nearer to or on the udder, or in the inguinal area, but not on the back of the udder, is associated with lowering of the tail and an outward movement of the hind leg which exposes the teat. The findings are considered in their relation to the natural situation immediately after birth of the lamb when the interchange of different types of tactile and other sensory stimulation gradually brings both partners into a situation in which the lamb can grasp the teat and suck.
Leaf Size Recognition and Evaluation of Some Attelabid Weevils (1) Chonostropheus Chujoi
Authors: Sakurai Kazuhiko
Published: April 2008

Leaf recognition of the female during cradle formation was studied using model leaves, young oak leaves moulded in several shapes; observation of behaviour preceding cutting and numerical analysis of cutting points were carried out. Females repeatedly perform a sequence of walking along the circumference via the leaf apex and then cut the leaf. Circumference length is the most probable determinant of the cutting point. It is hypothesized that females perceive the most protrusive point of the leaf, the leaf apex, and the circumference length by walking. A scheme, which consists of two mechanisms for circumference measurement, for the cutting point decision is proposed. Although females do not adjust the cutting point with respect to the number of eggs to be laid in the cradle, they perceive and use leaf area or something correlative to it, for the decision as to egg number.
Functions of Alliances in Contests Within Wild Gorilla Groups
Authors: Harcourt A.H. , Stewart K.J.
Published: April 2008

Primates frequently support other individuals in aggressive contests among group members. Several functions of such alliances have been suggested, some of them dependent on continued residence of females in the group of their birth. The distribution of alliances in the gorilla (Gorilla gorilla), in which both sexes emigrate, was analysed to investigate constraints on the use of alliances by primates. Functions were inferred on the basis of the identity of participants, it being assumed, for example, that a mother supported its infant against an adolescent male for a different reason than did an adolescent female who supported a dominant female against a subordinate female. Gorillas ally, we suggest, to protect relatives from harm, to provide them with access to otherwise unobtainable resources and, perhaps, to emphasise their dominance over rivals; it seems that individuals might also ally to obtain resources for themselves, and to establish supportive relationships with other group members. The first two inferred functions were the most common, involved in over 80% of alliances. The major contrast with female-resident primates lay not so much in the range of functions for which alliances were used, but in the lack of evidence that gorillas attempted to use alliances to manipulate the dominance status of their kin. Possible reasons for the contrast are that i) the widespread distribution and low quality of the gorilla's main food plants meant that ability in defence competition was not sufficiently advantageous for the benefits of raising the rank of kin to outweigh the costs; ii) the large difference in age among immature gorillas in the study area, which was mostly a consequence of the small group size, made it too costly to use support in contests to raise an individual's rank above that of older peers; iii) the leading male prevented the unequal investment among his offspring that would be entailed if individuals used alliances in contests to raise or reinforce the rank of kin. Currently, these possibilities cannot be distinguished.
Sexual Behavior of Male Northern Elephant Seals: III. the Mounting of Weaned Pups
Authors: Rose Naomi A. , Deutsch Charles J. , Le Boeuf Burney J.
Published: April 2008

1. Up to 50% of weaned northern elephant seal pups, Mirounga angustirostris, present on the Año Nuevo mainland rookery at the end of the breeding season showed evidence (tooth marks and injuries on the neck) of having been mounted by males. 2. Male-inflicted injuries on weanlings ranged from superficial tooth marks to deep gashes and punctures that bled and exposed the blubber. Most marks were superficial. 3. Approximately 0.5 % of all weaned pups died on the rookery from 1969-1990; about 35 % of the dead weanlings showed physical evidence that they were killed by males and males were suspected of having killed most of the rest. 4. Males mounting weanlings displayed many behaviors that are characteristic of male sexual behavior toward adult females and most weanlings responded like non-estrous females. Weanling mounts lasted an average of 2.8 min (N = 81) and were usually terminated when the male did not pursue an escaping weanling. There was no bias in the sex or the size of mounted weanlings. 5. Males also mounted conspecific juveniles (one and two years old), although these interactions were relatively infrequent because most juveniles were at sea during the breeding season. The behavior of males and juveniles during mounting attempts was qualitatively similar to weanling mounts; rarely, yearlings were killed by males. 6. Most mounters (91 %) were subadult males and were observed to mount weanlings only once in a breeding season. Occasionally, a male persisted in mounting weanlings repeatedly, within a season and across years. Weanling mounters did not differ from other males in their proximity to harems or in their copulatory success. 7. The proximate factors leading to weanling mounts appear to be male sexual inexperience, high libido, limited access to adult females, and stimulus generalization. Functionally, male sexual behavior toward weanlings appears to be a low-cost by-product of high male sexual motivation that may enhance a male's reproductive success. Weanlings exhibit behaviors, such as grouping into pods, seeking microhabitat refuges, and resisting mounts, that may reduce the chance of being mounted by a male or of being injured during a mounting attempt.
Broadcast Distance of the Mutual Display Call in the Emperor Penguin
Authors: Robisson Patrice
Published: April 2008

In the colonial emperor penguin Aptenodytes forsteri, the broadcast distance of the mutual display call (the distance over which the individual information conveyed by the call is transmitted) was determined. The variables measured were (1) the sound amplitude that averaged 94.8 dB SPL for birds facing toward the microphone and 85.7 dB SPL for birds facing away, (2) the sound attenuation that decreased with about 6 dB per doubling distance, (3) the ratio of the signal to the background noise of the colony which was 20-25 dB during the rearing period of chicks, and (4) the degradation of the signal structure by the scattering medium (penguin bodies) and distance, which affected the timbre, but not the two fundamental frequencies of the call that produced a beat phenomenon. This distance, 4-7 m indicates that the call is transmitted at short- or medium-range, and corresponds closely to the distance covered between two stops where a parent in search for its chick calls. The beat phenomenon undegraded by the scattering medium and distance is likely to serve individual recognition, assuming there is a relationship between the broadcast distance and the functional structure of emperor penguin call.
Sex-Biased Parent-Offspring Conflict
Authors: Redondo Tomas , Gomendio Montserrat , Medina Rosario
Published: April 2008

In species showing sexual dimorphism, parents may obtain different fitness returns per unit of parental expenditure from sons and daughters. Under these circumstances, parents are expected to invest extra resources in offspring of the most profitable sex. However, it is unclear whether sex-biased expenditure is the result of selection acting on parents, their offspring, or both. Current parent-offspring conflict theory is used to investigate whether sex biases in parental expenditure should be accompanied by sex biases in parent-offspring conflict. It is suggested that, in general, greater conflict should be expected between parents and offspring of the favoured sex. Specifically, greater conflict is predicted among mother-son dyads than among mother-daughter dyads in most polygynous birds and mammals. Data on domestic sheep, as well as empirical evidence available for other species (mainly ungulates), lends support to the prediction. The prediction is further extended to cercopithecine primates, a group which lacks clear sex-biases in parental investment. In this case, differences in fitness returns per unit of parental expenditure between the daughters of dominant and subordinate mothers are positively related to differences in the extent of mother-daughter conflict. The results from this study highlight the important role that selective pressures acting on the offspring phenotype may have played in the evolution of sex-biased patterns of parental investment.
Influence of Prey Movement On the Performance of Simple Detours By Jumping Spiders
Authors: Tarsitano Michael S. , Jackson Robert R.
Published: April 2008

The influence of prey movement on the performance of simple detours by salticids was investigated. Seven species were studied. Two subject species, Portia fimbriata and Portia labiata, are specialized web-invading species that eat other spiders. The other five species investigated (Euryattus sp., Euophrys parvula, Marpissa marina, Trite auricoma and Trite planiceps) are more typical cursorial hunters of insects. We provide evidence that: 1) salticids will initiate detours toward motionless prey; 2) salticids are more inclined to initiate detours toward moving than toward motionless prey; 3) salticids tend to complete detours even when prey that had been moving at the start remains stationary during the detour; 4) prey movement makes the salticid more likely to stalk and attack when prey is only a few centimetres away and in a position from which it can be reached by a straightline pursuit; 5) Portia is more inclined than the other salticids to initiate detours to motionless prey, then to stalk and attack motionless prey when close, than the other salticids are. Mechanisms that might account for Portia being different from the other salticids are discussed.
Sexual Imprinting in the Collared Dove (Streptopelia Decaocto)
Authors: TEN CATE Carel , Hilbers John , Hall Miriam
Published: April 2008

Although the occurrence of sexual imprinting has been demonstrated for doves, it is less well known how strong this effect is and which factors contribute to it. Therefore we examined whether cross-fostering collared doves (Streptopelia decaocto) to white ring doves (Streptopelia risoria) affected later mate preference and, also, whether the strenght of this preference depended on sex of the experimental birds, on the presence of siblings during rearing, on behaviour of the (foster)parents and on the behaviour of the stimulus birds during testing. Mate preferences were measured during choice tests using either stuffed or living stimulus birds, one of each species. The result showed (1) a strong effect of rearing species, but not of sex or presence of siblings on the later preference, (2) an overall bias towards preferring ring doves over conspecifics, both in tests using stuffed and tests using living stimulus birds, and (3) a tendency for the preference to shift towards collared doves with increasing age or testing experience. The findings indicate the occurrence of sexual imprinting in the collared dove and are compared with data on other species. The overall bias towards the ring dove was unexpected, but we suggest that this 'other species' bias may result from the same mechanisms which are responsible for the occurrence of an 'own species bias' in a number of other species.
Seafinding By Hatchling Sea Turtles: Role of Brightness, Silhouette and Beach Slope as Orientation Cues
Authors: Salmon Michael , Wyneken Jeanette , Fritz Elizabeth , Lucas Mark
Published: April 2008

Upon emerging from underground nests, sea turtle hatchlings immediately crawl toward the ocean. The primary cues used in orientation are visual but the nature of the visual cues was a matter of speculation. Hatchlings might also respond to secondary cues, such as beach slope. Experiments were carried out in an arena where specific visual and slope cues, simulating those present at nest sites, could be precisely controlled and manipulated. Subjects were green turtle (Chelonia mydas L.) and loggerhead (Caretta caretta L.) hatchlings. Both species oriented toward the more intensely illuminated sections of the arena. They also oriented away from dark silhouettes which simulated an elevated horizon, typical of the view toward land. Turtles responded primarily to stimuli (both silhouettes and photic differences) at or near eye level. When presented simultaneously with a silhouette and a photic gradient located in different directions, hatchlings oriented away from the silhouette and ignored photic stimuli. Under infrared light, both species oriented down slopes. However in the presence of nocturnal levels of visible light loggerheads ignored slope cues and responses of green turtles to slope were weakened. The data suggest that loggerhead and green turtle hatchlings usually find the sea by orienting away from elevated silhouettes. This is a prominent and reliable cue for species which typically nest on continental beaches.
Songs and Sexual Responses of Female White-Crowned Sparrows (Zonotrichia Leucophrys) From a Mixed-Dialect Population
Authors: Chilton Glen , Ross Lein M.
Published: April 2008

Some researchers have suggested that female songbirds mate with males singing local song types in preference to males singing dialects from more distant populations. Such behaviour might promote genetic isolation among dialect populations. We studied captive female white-crowned sparrows (Zonotrichia leucophrys) from a population in which two song types were equally common, as a model for behaviour at dialect boundaries. Subjects were captured as adults, and the song type of the mate of each was known. Treated with estradiol, females gave sexual displays in response to playback of conspecific male song. As a group, they solicited no more strongly to either local song type, suggesting that males singing either local song type should be able to attract mates. Individuals solicited no more strongly to their mate's song type than to the other local song type. This suggests that strength of response of captive females to song playback may not accurately reflect the behaviour of free-living individuals. Subjects were also treated with testosterone to induce singing. Individuals sang their mates' song type more often than expected by chance. Given that female white-crowned sparrows in this population do not consistently choose mates of one song type, we develop the argument that females learn, for performance, the song type of their first mate. However, the type of song learned for performance appears unlikely to restrict their subsequent mate choice decisions. Our results suggest that female white-crowned sparrows do not base their choice of mates on dialectal variation in male song, and that it is unlikely that mate choice decisions based on song dialect promote the genetic isolation of dialect populations.
Relationship Between Growth, Size, Molting, and Number of Antennal Segments in Orchestia Traskiana Stimpson (Amphipoda, Talitridae)
Authors: Page Henry M.
Published: April 2008

Dans cette étude on a examinée la possibilité d'utiliser le nombre d'articles ou podomères comporté par la flagelle des antennes, comme indice de rang de mue chez l'amphipode Talitridé Orchestia traskiana. Les résultats montrent que les mâles et les femelles possédant jusqu'à 13 podomères acquièrent, en moyenne, un podomère supplémentaire lors de la mue. Les différences survenant dans la fréquence d'acquisition des podomères lors de la mue, entre les mâles et les femelles possédant plus de 13 podomères, semblent être liée à la différence existante entre les taux de croissance respectifs des sexes. Il a été remarqué que la longueur moyenne du corps d'un O. traskiana possédant entre 10 et 13 podomères, telle qu'elle a été mesurée dans une population prélevée sur le terrain, subit des variations saisonnières, ce qui suggère ainsi une variation saisonnière dans l'accroissement de la mue.