bluuebunny/crossref_metadata_2025 huggingface dataset:
Individual Recognition of Nestling Distress Screams By European Starlings (Sturnus Vulgaris)
Authors: Chaiken Marthaleah
Published: April 2008

Individual recognition of nestling distress screams by European starlings (Sturnus vulgaris) was assessed by comparing the responses of free-living parents to playbacks of screams recorded from their own young or from neighbouring chicks. Individual variation in the acoustic structure of distress screams was analysed to assess whether they were likely to afford an acoustic basis for individual recognition. Parents hearing screams of their own young were significantly more likely to make diving attacks on the speaker than parents hearing the screams of neighbouring chicks. Thus nestling screams appear to function as individually indentifiable calls for aid. Multivariate analysis of variance employing 9 acoustic parameters of nestling screams revealed significant differences among groups of screams recorded from different chicks, suggesting that screams could afford a suitable basis for individual recognition. Post-hoc F-tests suggest that the period and extent of rapid frequently modulations would provide the best cues to the identity of the caller.
Clans and Harems in a Colony of Hamadryas and Hybrid Baboons: Male Kinship, Familiarity and the Formation of Brother-Teams
Authors: Colmenares Fernando
Published: April 2008

Three features of the hamadryas society, Papio hamadryas, which are quite unique among Old World monkeys, are its multileveled structure (i.e. harems, clans, bands, troop), the reported pattern of female dispersal (i.e. males tend to remain in their natal clans whereas females tend to move between clans and bands), and the special bonds that develop between adult males. It has also been hypothesized that the males of a clan are genetically related. In this paper a causal approach is adopted in order to investigate the proximate factors which can account for the structure/dynamics of socio-spatial group organization observed over two years in a large colony of hamadryas and hybrid baboons housed in an outdoor enclosure in the Madrid Zoo, containing 18 adult males with known kin relations. I first examined the types of grouping observed in the colony and the alternative social strategies used by the different male individuals during their ontogenetic trajectories for acquiring, and maintaining, females. Since the hamadryas baboon is considered a female-transfer species, I studied whether the sex that stays, that is, the males, developed some kind of mutual affiliative relationship, as one would predict, and whether their inter-male bonding preferences were based on genetic relatedness or on familiarity (i.e. sharing the same developmental environment during socialization).
Copulation and Mate Guarding in the Yellow-Billed Magpie Pica Nuttalli and a Comparison With the Black-Billed Magpie P. Pica
Authors: Birkhead T.R. , Clarkson K. , Reynolds M.D. , Koenig W.D.
Published: April 2008

Yellow-billed magpies breed in loose colonies. Extra-pair courtship is frequent, and a comparison (I) between two adjacent areas with different inter-nest distances, and (2) with solitary, territorial European black-billed magpies, indicates that either an aggregated distribution of nests, or a relatively loose territorial system in yellow-billed magpies increases opportunities for extra-pair behaviour. Male yellow-billed magpies guard their partner by closely following them from five days before the first egg is laid. Pair copulations were infrequent, occurring 3 or 4 times per clutch, and mainly over days -5 to -3. Territoriality, which is most pronounced during the female's fertile period, may enable the male to guard his partner while simultaneously foraging to provide her with food.
'Food' Calls Produced By Adult Female Rhesus (Macaca Mulatta) and Japanese (M. Fuscata) Macaques, Their Normally-Raised Offspring, and Offspring Cross-Fostered Between Species
Authors: Owren Michael J. , Dieter Jacquelyn A. , Seyfarth Robert M. , Cheney Dorothy L.
Published: April 2008

We tested a recent claim that rhesus and Japanese macaque offspring cross-fostered between species exhibit vocal learning by producing 'food' calls typical of their adoptive rather than their genetic species (MASATAKA & FUJITA, 1989). Our study population consisted of four groups of socially-reared animals housed outdoors - two of each species. Food calls produced by adult female rhesus and Japanese macaques did not differ at the species level, although individual differences were clearly present. Food calls produced by normally raised offspring differed both between individuals and between species. In spite of statistically significant differences, however, immatures in the two species still showed substantial overlap on every acoustic feature that was measured. Evidence from four cross-fostered offspring was equivocal. Two rhesus macaques raised in Japanese macaque social groups produced calls that were typical of their own species. Some measurements from calls produced by two cross-fostered Japanese macaques fell closer to mean values for normal rhesus than for those of their own species. However, these measurements were still within the observed range of variation shown by normally raised Japanese macaques. We conclude that food calling behavior of cross-fostered Japanese macaques may have shown modification, but that any such effect was not based on a species-specific adult model. Given the variability of these sounds and the lack of species differences in adult female vocalizations, food calls do not present a good opportunity to test for vocal learning in cross-fostered rhesus and Japanese macaques.
Daytime and Nighttime Enuresis: a Functional Disorder and Its Ethological Decoding
Authors: Haug-Schnabel G.
Published: April 2008

In wetting children (functional enuresis nocturna and diurna) days and nights with perfect bladder control alternate with wet days and nights. Changes of behaviourial regulation are responsible for the temporary disfunction of bladder control when awake or asleep. By means of long-term behaviour observations of wetting children in their families and in kindergarten we succeeded in isolating different forms of wetting. Wetting during zealous play, referred to as enuresis diurna type A, occurs when the bladder is filled during an intensive play activity. Wetting due to conflict (enuresis diurna type B) as well as nighttime wetting (enuresis nocturna) occur independently of the filling of the bladder, but directly depending on preceding stressful events. Step by step the information from the behaviour observations are incorporated into the functional diagram of the regulation of micturition until the elements of the faulty regulation in functional enuresis can be demonstrated. In the wetting child the need for loving attention has become the signal for the micturition. This learned association is the pathological part within the behaviour regulation. Functional enuresis is an example for a modification of biologically adaptive behaviourial elements by unfavourable environmental conditions.
Monogamy in the European Starling
Authors: Wright Jonathan , Cuthill Innes
Published: April 2008

Recent theoretical and experimental studies appear to provide a comprehensive explanation for the evolutionary, and short-term, stability of biparental care in birds. However, much of the intraspecific variation in the absolute and relative contribution by the male and female remains to be explained. Most studies of the natural variation across pairs reveal positive correlations between the level of male and female nest defence or brood provisioning, but some species show negative relations, or between-season variability in the direction of the relationship. This study examines the determinants of male and female provisioning rate in monogamous European starlings (Sturnus vulgaris), in terms of the patterns of male display, pairing patterns, laying phenology and clutch attributes. There was assortative pairing by body size and, controlling for female body size, larger males attracted relatively fecund mates. Males that sang relatively more, controlling for these body size effects, were paired with females that laid earlier. Female nest provisioning rates to experimentally standardized broods were positively correlated with female size, but male provisioning rates were unrelated to either song or any other attributes of themselves or their mates.
Territorial Marking With Faeces in Badgers (Meles Meles) : a Comparison of Boundary and Hinterland Latrine Use
Authors: Roper T.J. , Conradt L. , Butler J. , Christian S.E. , Ostler J. , Schmid T.K.
Published: April 2008

Badgers (Meles meles) defecate, urinate and scent mark at latrines which seem
to have a territorial function. The main aim of the present study was to
compare defecation patterns at boundary and hinterland latrines, in order to
test the hypothesis that these two types of latrine have a similar function.
We investigated latrine use by means of a year-round survey of all the
latrines in 7 badger territories, by bait-marking of 15 territories, and by
monitoring latrine use in 6 radio-collared badgers belonging to three social
groups. The spatial distribution of latrines within a territory was bimodal,
with the greatest densities oflatrines close to the outside, and close to
the centre, of the territory respectively. Boundary latrines were larger and
more consistently used than hinterland latrines, but these differences could
be accounted for by the fact that boundary latrines are visited by the
members of more than one social group. Defecation at latrines was subject to
seasonal variation, with a major peak in latrine use in spring and a minor
peak in autumn. The spring peak was largely attributable to an increase in
the use of hinterland latrines, the autumn peak to an increase in the use of
boundary latrines. Males visited boundary latrines considerably more often
than did females, but both sexes visited hinterland latrines equally often.
Overmarking occurred equally often at both types of latrine and involved
animals from the same as well as from different groups, but there was a
significant tendency for more between-group than within-group overmarking.
Overmarking occurred mainly on fresh, as opposed to old, faeces deposits.
The sex and seasonal differences in use of boundary latrines suggest that
these function at least partly as a form of mate-guarding, to deter
neighbouring males from entering a territory for mating purposes. It is less
clear why females mark at hinterland latrines. One possibility, consistent
with the observed spatial distribution of hinterland latrines, is that they
function to defend the main burrow system, which is used for breeding;
another is that they carry information about social status. Overmarking
probably serves to obliterate the marks of competitors, which are members of
neighbouring social groups in the case of boundary latrines, but may be
members of the same social group in the case of hinterland latrines. We
conclude that previous ideas about the function of territoriality in
badgers, and about the information conveyed by latrines, are
oversimplified.
Incubation Development and Asynchronous Hatching in Junglefowl
Authors: Meijer T. , Siemers I.
Published: April 2008

In gallinaceous birds and other nidifugous species, it is thought that
effective incubation does not start before the last egg is laid, and young
hatch synchronously (LACK, 1968). We investigated the egg-laying and
nest-attendance pattern of the precocial nidifugous red Burmese Junglefowl
Gallus gallus spadiceus, and its consequences for the asynchrony of embryo
development and of hatching. Eggs were laid in sequences, followed by pause
days. Egg-weight in these sequences decreased by 0.6 g/egg. When laying,
females sat in the nest for 1-3 h/day, and attended the nest overnight on
days on which the last eggs of a clutch were laid. At the moment the last
egg was laid, first eggs were already attended for 40 h (range 16-84 h),
which resulted in extreme developmental asynchrony at the end of laying
(measured as the diameter of the area vasculosa). Last eggs of clutches
decreased markedly in weight (by more than 1 g/egg) and had shorter
incubation times than the heavier first eggs. Eggs hatched asynchronously
over a period of 15 h (range 7-33 h) and in the order of laying. The
development of incubation behaviour, asynchrony of embryo development and of
hatching of the precocial nidifugous Junglefowl, corresponded to a high
degree to what is known of altricial species.
Matman: a Program for the Analysis of Sociometric Matrices and Behavioural Transition Matrices
Authors: DE VRIES Han , Netto Willem J. , Hanegraaf Peter L.H.
Published: April 2008

MatMan is a program for performing a variety of ethological analyses of frequency (interaction) matrices and transition matrices. These analyses include linear hierarchy indices for dominance matrices (APPLEBY, 1983), reorganization of a dominance matrix such that the subjects are in rank order, matrix correlation methods such as Mantel's test (MANTEL, 1967) and rowwise matrix correlation (DE VRIES, 1993), methods based on information theory (STEINBERG, 1977), and the calculation of expected and residual values in transition matrices with defined or undefined diagonal. In addition, MatMan offers some useful options for manipulating matrices. Import of matrices from The Observer (NOLDUS, 1991) and SAS is, within certain limitations, possible. Export of matrices is possible to the programs CORAN (1985), Vegrow (FRESCO, 1989), NCSS (HINTZE, 1987), SAS and SPSSPC.
The Chick's Preference for Certain Features of the Maternal Cluck Vocalization in the Domestic Fowl (Gallus Gallus)
Authors: Kent J.P.
Published: April 2008

The predominant frequency, rate of clucking and intensity of the maternal cluck vocalization of the broody hen (Gallus gallus) are described. The frequency, rate of clucking, and level of intensity of the cluck vocalizations were altered independently of each other. Three-day-old chicks were given a simultaneous choice test between the normal and an altered cluck or between the two altered clucks in a 'T' shaped simultaneous choice test apparatus. No significant preferences were found when the frequency was increased or decreased by 25% (Experiment 1A) but the chicks significantly prefer the normal cluck over a cluck with a 33% increase in frequency. The preference for the normal cluck over the 33% decrease in frequency was nearly significant (Experiment 1B). Thus, there exists an optimal frequency range for the maternal cluck vocalization of the domestic hen. When the rate of clucking was increased or decreased by 25% the chicks preferred the higher rate of clucking in all conditions (Experiment 2). However, the highest rate of clucking used in this experiment was close to that of the normal cluck. When the intensity was increased or decreased by 100% no significant preferences were found in any choice test (Experiment 3). This contrasts with earlier findings possibly due to a methodological difference.
Brood Size and Offspring Age Affect Risk-Taking and Aggression in Nest-Guarding Common Gobies
Authors: Magnhagen Carin , Vestergaard Klaus
Published: April 2008

The importance of brood size, offspring age, and male size for parental care behaviour was studied in the common goby, Pomatoschistus microps. In field observations, the aggression of nest guarding males was measured as attacks towards a finger when disturbing the nest. Attacking males had larger and more developed clutches compared to non-attacking males, but did not differ in body size. In another set of observations nest guarding males were exposed to a predator (eelpout, Zoarces viviparus) and subsequently chased away from their nests. Time away from the nest decreased significantly with egg developmental stage, i.e. with the time the male had spent guarding a particular brood. However, no correlations with male body length or numbers of eggs in the nest were found. We conclude that male common gobies evaluate future reproductive success by using brood age and brood size as cues for making decisions about risk-taking and aggressive behaviour during parental care.
The Concept and Definition of Dominance in Animal Behaviour
Authors: Drews Carlos
Published: April 2008

The concept of dominance has contributed greatly to our understanding of social structure in animals. Over the past three decades, however, a variety of concepts and definitions of dominance have been introduced, leading to an ongoing debate about the usefulness and meaning of the concept. Criticisms aimed at one definition of dominance do not necessarilly apply to other definitions. Existing definitions can be structural or functional, refer to roles or to agonistic behaviour, regard dominance as a property of individuals or as an attribute of dyadic encounters, concentrate on aggression or on the lack of it, and be based either on theoretical constructs or on observable behaviour. Thirteen definitions of dominance are reviewed, and their usefulness assessed with respect to their descriptive value. The predictive and explanatory values of definitions are specific to the questions asked in each particular study and are not considered as criteria to judge the usefulness of the dominance concept. By virtue of its high descriptive value, the original definition of dominance by SCHJELDERUPP-EBBE (1922, Z.Psychol. 88: 226-252) emerged as the basis to formulate a structural definition with wide applicability and which reflects the essence of the concept: Dominance is an attribute of the pattern of repeated, agonistic interactions between two individuals, characterized by a consistent outcome in favour of the same dyad member and a default yielding response of its opponent rather than escalation. The status of the consistent winner is dominant and that of the loser subordinate. Dominance status refers to dyads while dominance rank, high or low, refers to the position in a hierarchy and, thus, depends on group composition. Dominance is a relative measure and not an absolute property of individuals. The discussion includes reference to the heritability of dominance, application of dominance to groups rather than individuals, and the role of individual recognition and memory during agonistic encounters.
Responses of Foraging Sanderlings To Human Approaches
Authors: Roberts Gilbert , Evans Peter R.
Published: April 2008

Sanderlings Calidris alba were put to flight by walking towards them as they foraged at the water's edge on a sandy beach. Studies of the responses of birds to disturbances have concentrated on the relationship between group size and the distance from the cause of the disturbance at which members of the group take flight (the flight reaction distance). The study of responses to disturbance is extended to consider the frequencies with which birds took flight; their flight directions (whether towards the approacher and then in behind or whether ahead of the approacher); and the distances to which they flew. The nearest birds to the approacher tolerated approaches to well within the range at which the approacher should have been visible. When the nearest birds flew, the likelihood of other birds flying decreased as the distance by which they were further away from the approacher than the nearest birds increased. Birds further away were more likely to fly when more birds flew from nearer to the approacher. The nearest birds tended to fly in behind the approacher while those further away from the approacher flew further ahead. The findings suggested that the birds were acting so as to maximise their foraging time by minimising both the number of flights they made and the distance of each flight, subject to not tolerating close approaches.
Size Assortative Mating in the Yellow Dung Fly Scatophaga Stercoraria
Authors: Otronen Merja
Published: April 2008

In the yellow dung fly, Scatophaga stercoraria, pairs copulating in the grass or ovipositing on a dropping were size assortatively mated. However, pairs initiating copulations showed no assortative pattern: 1) Pairs formed at different times from the deposition of droppings or in different parts of the mating area showed no consistent relationship in size. 2) Successful males in copulation attempts involving several males were larger than in single male attempts but these type of copulation attempts were not more frequent with large females. 3) Female display did not result in assortative mating although displaying females copulated with a relatively larger male than other females. During copulation and oviposition, single males attempted to take-over paired females which resulted in the separation of many initial pairs. Pairs in unsuccessful take-over attempts were size assortatively mated but not in succesful take-overs. Pairs flying between droppings were also size assortatively mated suggesting that assortatively mated pairs are more likely to move long distances than other pairs. In addition, density affected pair formation. The difference from the expected female-male size ratio decreased with increasing density among copulating pairs suggesting that assortative mating is more common at high density droppings. Assortative mating in the yellow dung fly therefore results from male aggression against copulating and ovipositing pairs. During take-over attempts non-assortatively mated pairs are likely to be separated. High male density with increased level of male encounter rate is likely to contribute to this process.
Determinants of Time Allocation By Adult and Yearling Black-Tailed Prairie Dogs
Authors: Loughry W.J.
Published: April 2008

The time budgets of all adult and yearling black-tailed prairie dogs in a wild population were measured in 14 separate samples between late April and mid-August 1989. In general, males were more vigilant and fed less than females did. This sex difference was due largely to the behavior of males that had sired offspring; non-fathers behaved more like females. As the summer progressed, prairie dogs spent more time feeding and less time vigilant. The lone exception to this pattern was mothers, who fed less and spent more time vigilant as the summer progressed. Other influences on time allocation produced similar effects for all sex/parental groups: animals were more vigilant while in tall vegetation and in the early morning as opposed to mid-day or evening. Environmental (e.g. weather) and social (e.g. number of other adults and pups present) effects on time allocation were analyzed via multiple regression. Of all potential influences, distance from the nearest burrow seemed to have the most consistent impact on time allocation for all individuals. These results point to strong effects of sex, parental status and environmental context in determining the particular pattern of time allocation observed in an individual prairie dog.
Oviposition Behaviour of Diphagous Parasitoids (Hymenoptera, Aphelinidae): a Case of Intersexual Resource Partitioning?
Authors: Walter G.H.
Published: April 2008

Female diphagous parasitoids are endoparasitic as larvae, whereas their males are ectoparasitic. It is possible that males, during their development, eliminate competitors, and this has been proposed as the selective advantage to male ectoparasitism. In this way resources would be partitioned between the sexes. The hypothesis was tested experimentally by observation of whether mated females were capable of recognizing parasitized hosts, and whether they then deposited male eggs on them (because ectoparasitic larvae are supposed to be good competitors). The behaviour of individual Coccophagus bartletti ANNECKE & INSLEY (Aphelinidae) wasps did not follow prediction, and an alternative hypothesis is proposed. Selection pressures from the environment (e.g. host) need not be the same for both sexes, and if male eggs of the pre-diphagous aphelinid were treated differently at oviposition from female eggs (as is found in at least one extant species of aphelinid with otherwise conventional host relationships), a host shift at speciation could account for the divergence in host relationships of the sexes.
Effect of Familiarity With the Mother and Kinship On Infanticidal and Alloparental Behaviour in Virgin House Mice
Authors: D'Amato Francesca R.
Published: April 2008

Experienced male and female house mice encountering a newborn pup can display indifference, parental or infanticidal behaviour. Characteristics of the pup such as sex and strain do not seem to influence the likelihood of infanticide, in contrast to attributes of the adult subjects (age, sex, strain, sexual experience, previous cohabitation with the mother, reproductive condition). This study investigated the effect of kinship and/or familiarity with the mother on male and female behaviour towards pups. The subjects were 100-day-old Swiss-Webster virgin male and female mice. After 24 hours of isolation, a 24-36 hrs old pup was introduced into their home-cage and their behaviour was recorded for 15 min. Male and female mice killed related as well as unrelated pups. Females killed fewer offspring of females with whom they had cohabited until 3 weeks before the study, in comparison with the offspring of completely unfamiliar females. When females were exposed to the offspring of females of comparable familiarity but different relatedness, they devoted more parental behaviour towards more related pups. This suggests that, even if familiarity plays a major role in determining females' behaviour, kin recognition occurs and is responsible for differences in alloparental care distribution. The behavioural strategies adopted by male and female mice are interpreted on the basis of differences in activity range of the sexes within a deme (breeding group).
Sex Recognition in Zebra Finch Males Results From Early Experience
Authors: Vos Dave R.
Published: April 2008

This study investigated whether sexual imprinting plays a role in the recognition of the sex of conspecifics. Subjects were zebra finch males that had been raised with either normal pairs, white pairs or pairs of both morphs. They were tested for their preferences in six two-stimuli tests covering all combinations of both morphs of either sex. Males of all groups showed a clear preference for females of their mother's morph over males of their father's morph. Moreover, a majority of the males from mixed parentage preferred a male of their mother's morph over a female of their father's morph, indicating that morphological characteristics are more important than behavioural differences for discrimination between the sexes. This was confirmed in a subsequent series of tests in which males raised by parents of the white morph, which are sexually dimorphic only in respect to the intensity of the red colour of the bill, were given a choice between a white male with his bill painted orange and a white female with her bill painted red. All males of this group preferred to court the male in this test. In addition to differential responses in a sexual context, males showed discrimination in an aggressive context; that is, most aggression was directed towards stimulus birds resembling the father. The implications of these results for the evolution of sexual dimorphism and sexual selection are considered.
Dynamic Pair Bonds in Hylobatids: Implications Regarding Monogamous Social Systems
Authors: Palombit Ryne
Published: April 2008

Descriptions of monogamy in the gibbons (Hylobates spp., Hylobatidae) have generally emphasized features derived from inference rather than direct observation: 1) adults mate for life; 2) the genetic structure of groups corresponds with a ''nuclear family'' pattern of parents and their mutual offspring; 3) first mate acquisition is achieved when two ncwly dispersed, unaccompanied, young adults of opposite sex establish a new pair and territory together. The six-year history of mating associations of adults in three groups of sympatric, wild siamang (Hylobates syndactylus) and three groups of white-handed gibbon (Hylobates lar) at the Ketambe Research Station (Sumatra, Indonesia) challenge the generality of these assumptions. These longitudinal sociodemographic data suggest that gibbon pair bonds are not necessarily life-long and that adults may leave mates permanently or temporarily, sometimes in order to exploit new reproductive opportunities. Of 11 heterosexual pair bonds that existed at some time during the study, only two were terminated by death of one adult, whereas five were terminated when one adult left its current mate. In some cases, the ''deserting'' individual left its mate and joined a neighboring adult of opposite sex who had recently lost its own mate through death or desertion. This turnover in pair bond membership generated stable, ''non-nuclear'' family groups in which the replacement mate was not the parent of the resident nonadults. Mechanisms of mate acquistion observed at Ketambe included two processes that may also promote non-nuclear families. A young adult may obtain its first mate by: 1) replacing an adult of the same sex in a neighboring group or in the group in which it resides; 2) establishing a new pair bond (and territory) with another unmated young adult of opposite sex who is, however, accompanied in dispersal by juvenile conspecifics from its group. Finally, observed extra-pair copulations (in siamang) suggested an additional, but as yet unspecified potential for variable relatedness between adult males and resident nonadults. Review of other long-term histories of pair bonds in wild gibbons and of studies of socio-sexual behavior in captivity reinforce the conclusion that the apparent temporal stability and underlying behavioral inflexibility of pair bonds has been over-emphasized. Although data on behavior and reproduction are limited, they nevertheless suggest strongly that the mating and social systems of these monogamous primates are considerably more dynamic and complex than previously appreciated.
Exchange of Grooming for Allomothering in Female Patas Monkeys
Authors: Muroyama Yasuyuki
Published: April 2008

The question is asked whether grooming is exchanged for allomothering in patas monkeys (Erythrocebus patas). Six adult females in one group were observed during the non-birth season (no infants) and the birth season when three females had given birth to an infant. During the non-birth season the exchange of grooming and soliciting for it indicated reciprocity between non-kin. During the birth season, however, non-mothers groomed mothers much more than vice versa, and soliciting was shown more by mothers. This is in accord with the hypothesis that grooming is offered in order to be permitted to allomother. In addition, allomothering was often preceded and followed by grooming. Investment and reciprocity by unaffiliated (rarely grooming) non-kin females tended to occur most promptly. This is in accord with the hypothesis that fairness of reciprocity can be easier assessed if reciprocal acts occur immediately. Effects were less in affiliated non-kin pairs (frequently grooming), and least between kin.
Seahorses Exhibit Conventional Sex Roles in Mating Competition, Despite Male Pregnancy
Authors: Vincent Amanda C.J.
Published: April 2008

In seahorses, only males undergo a pregnancy. It had been tacitly and explicitly assumed that seahorses were sex role reversed (that females competed more intensely than males for access to mates), on the basis that male pregnancy so limited male reproduction as to produce a female-biased operational sex ratio (OSR). However, this supposition had never been investigated. The laboratory experiments in this paper demonstrate that, contrary to expectations, seahorses exhibit conventional sex roles: male seahorses compete more intensely than females for access to mates, on both the first and final days of courtship. Competing males are more active than competing females in those courtship and competitive behaviours common to both sexes, and only males exhibit uniquely competitive behaviours (wrestling and snapping). Males which succeeded in copulating are heavier than their rivals and copulating seahorses of both sexes generally are more active in courtship and competition than are their unsuccessful rivals. The finding that seahorses maintain conventional sex roles requires us to reconsider the impact of male pregnancy on the OSR.
The Process of Syllable Acquisition in Adult Indigo Buntings (Passerina Cyanea)
Authors: Margoliash Daniel , Staicer Cynthia , Inoue Sue A.
Published: April 2008

Vocal learning in adult indigo buntings was studied by monitoring socially paired males housed together in sound isolation boxes. Two of three yearlings socially paired with older birds in early spring acquired new syllables and reorganized their stereotyped and plastic songs, while eleven yearlings socially paired later in the year largely failed to acquire new material, as did the older adults socially paired at various times of year. Yearlings changed their stereotyped songs to more closely match their tutors' by replacing syllables or by inserting new syllables. This song matching involved two processes in which adult plastic song played a role: (1) new syllables were developed in plastic song, and (2) newly mastered or pre-existing syllables were transferred from plastic song into stereotyped song. Morphological similarity between yearlings' and tutors' syllables strongly influenced which syllables yearlings retained. After social pairing, matching syllables tended to be delivered more frequently by yearlings and become incorporated into their stereotyped songs, while non-matching syllables tended to decline in use or be discarded altogether. New syllables were formed from existing syllables most morphologically similar to the "target" syllable, through transformation and combination of existing syllables. As new forms became more common, old forms declined and eventually were discarded. Our data suggest that adult indigo buntings maintain the ability to sing stereotyped songs while new material is mastered, and held in reserve, in plastic song. Acquisition of new syllables in yearling indigo buntings requires trial-and-error learning, but proceeds without overproduction and subsequent attrition of distinct syllable types, and does not substantially rely on improvisation and invention. Rather, syllable acquisition and changes to stereotyped songs are strongly influenced by the pre-existing syllable repertoire.
Effects of Parent and Offspring Food Rations On Parental Care in the Convict Cichlid Fish (Pisces, Cichlidae)
Authors: Lavery Robert J. , Kieffer James D.
Published: April 2008

Animals may provide more care for their young under certain environmental conditions. For instance, if food is plentiful parents may invest more in the current brood than if food is scarce, assuming that food abundance is correlated with parent and offspring condition. In this experiment, we manipulated food levels (low vs high) for both parents and offspring to determine if parental care is influenced by parental and/or offspring condition in the convict cichlid, Cichlasoma nigrofasciatum. Parents which were fed a higher ration gained weight, whereas parents fed a lower ration lost weight. Similarly, young which were fed a higher ration were significantly larger than young fed a lower ration. Parents which were fed a higher ration defended their brood more vigorously than parents fed a lower ration. Offspring condition had little effect on parental care. Furthermore, females consistently invested more than males. The results show that parental convict cichlids adjust care in response to their own food supply rather than that of their offspring.
Are Chemical Cues as Effective as Pup Contact for Inducing Paternal Behaviour in Meadow Voles?
Authors: Storey Anne E. , Walsh Carolyn J.
Published: April 2008

We tested what social cues mediate the transition from non-parental to parental behavior in male meadow voles, based on our previous findings that postpartum interaction with mate and pups was the most effective social experience for making males paternal. Males housed with their mates and pups for a day were more paternal and less aggressive to unrelated pups than males removed from their mates before parturition. Males housed with their mates, but with the litter removed, interacted with pups but were initially as likely to be aggressive as males with no exposure to mates and pups. These results suggest that the mate facilitates interaction with pups, but exposure to pups accelerates the sensitization process. Twenty-four hours of exposure to chemical cues from the mate and pups (mother and litter in cage with wire mesh floor suspended above male's cage) eliminated male aggression towards pups, but physical contact was necessary to enhance positive interactions with pups. Exposure to chemical cues from parturient mates reduced aggression, whereas cues from non-mates were not effective. These results may explain our previous findings that females keep sires removed during pregnancy out of the nest for about a day after reintroduction (while males become sensitized via chemosignals), and continue repelling unfamiliar males (that would not be sensitized by chemical cues from non-mates).
Prior Residence Effect in the Dart-Poison Frog, Dendrobates Pumilio
Authors: Baugh Julia R. , Forester Don C.
Published: April 2008

Each of 32 male, Dendrobates pumilio (red phase) were allowed to establish a territory in one half of a 40 liter aquarium. Each enclosure contained a substrate of Sphagnum, a potted plant, and a water dish. Males occupying the same aquarium were prevented from seeing one another by an opaque barrier. In the first experiment, residents were presented with a conspecific intruder matched for size and color. Based on a numerical index of aggression, residents were consistently dominant over intruders. When reciprocal trials were conducted, the results were reversed (i.e. residents were dominant over males to which they previously had been subordinate). The success of resident males was not influenced by the size of conspecific intruders. In addition, residents consistently dominated a sympatric confamilial intruder (Phyllobates lugubris). Removal experiments revealed that resident males recognize and defend their enclosures after 3, and to a lesser degree, 6 days of isolation. We also examined the effect of territorial markers on the prior residence effect by stepwise removal of the plant and Sphagnum. Residents aggressively defended enclosures in both experiments. When Sphagnum was removed from the resident's enclosures and placed in a previously unused aquaria, 7 of 10 males exhibited dominance over conspecific intruders.
Migration Alliances and Coalitions Among Adult Male South American Squirrel Monkeys (Saimiri Sciureus)
Authors: Mitchell Carol L.
Published: April 2008

1. Male South American squirrel monkeys form groups whose composition remains stable over migrations between troops. These groups are called 'migration alliances'. 2. Members of migration alliances support one another against other males through coalitions in genital display bouts both during immigration and throughout the year. Male alliances do not function to overcome female dominance. 3. Seasonal reproduction in squirrel monkeys may influence male alliances by a) intensification of within-group competition during the mating season, and b) production of temporally and spatially fluctuating mating opportunities between groups.
Affiliative Behaviour Between Adult Males of the Genus Macaca
Authors: Hill David A.
Published: April 2008

1. Relations between sexually mature males in multi-male groups of macaques have been characterised as largely antagonistic, with bonnet macaques being the only frequently cited exception. A survey of the literature indicated that affiliative behaviour between males is more widespread than has been supposed. 2. Factors were examined which may influence the nature of relations between adult males. In all macaque species for which there are adequate data, males commonly move between groups, making it unlikely that kinship between adult males is an important factor in natural groups. 3. Affiliative behaviour between adult males is more frequently observed in small groups, with sex ratios closer to parity, than in large groups with more uneven sex ratios. Two factors are thought to influence this association. First, most large groups with highly skewed sex ratios were provisioned. Provisioning results in increased levels of aggression and tension, which may preclude the formation of affiliative relationships. Second, in groups with highly skewed sex ratios males can find many potential grooming partners among the females and their offspring. Where the sex ratio is more even there may be a shortage of potential partners among the natal animals, and males may form relationships with other males as an alternative. 4. Much of our knowledge of macaque societies has come from provisioned populations. Findings made under such conditions must be verified with data from natural populations, wherever possible, especially where competition may have an influence on the patterns of behaviours observed.
Alternative Reproductive Tactics and Reproductive Success in Male Rhesus Macaques
Authors: Berard John D. , Nurnberg Peter , Epplen Jorg T. , Schmidtke Jorg
Published: April 2008

Male rhesus macaques on Cayo Santiago use rank-dependent alternative reproductive tactics. High-ranking males can form long-term consorts and guard female mates while low-ranking males frequently resort to quick copulations under the cover of vegetation. No single reproductive tactic provided the Group S males with a definitive reproductive advantage during the one-year study. Males using the long-term tactic and the quick, stealth tactic sired five offspring each, but fewer males used the long-term consort tactic. Males using the long-term reproductive tactic have significantly greater mating success than males using the quick, sneaky tactic, and may have greater reproductive success. The highest-ranking males who form long-term consorts had the greatest degree of reproductive success. This indicates that for the highest-ranking males, forming long-term consorts is the most effective reproductive tactic. The effectiveness of alternative tactics for high-ranking males (i.e. consort disruption and possessive following) was equivocal. Consort disruption had no immediate effect on reproductive success. Possessive following may have resulted in the siring of two offspring by the alpha male, but was ineffective in other cases, where the females were inseminated by subordinate males. The effectiveness of the quick, furtive tactic was demonstrated by the siring of 45% of the infants by males who used this tactic.
Male Courtship Displays, Ornaments and Female Mate Choice in Captive Red Jungle Fowl
Authors: Zuk Marlene , Popma Stacey L. , Johnsen Torgeir S.
Published: April 2008

We studied the role of male courtship behaviour in female mate choice in red jungle fowl (Gallus gallus), the ancestor of domestic chickens. The traits most highly correlated with behavioural displays were those most relied upon by females in making mate choice decisions. These traits (comb length, comb colour, eye colour, and spur length) are highly condition-dependent in jungle fowl. Females chose males that displayed at a greater overall intensity in the period after the female was allowed to interact with the males (post-release), but were indifferent to displays during the period before the female could approach the roosters (pre-release). After accounting for the effect of morphology on mate choice, waltzes were the only display that explained a significant amount of variation in male mating success. Chosen and rejected males had different display rates even when the female was not present. Plasma testosterone level was correlated with pre-release behaviours, but not with post-release behaviours or mating success.
Development of a Selective Response To an Adult Vocalization in Nestling Black-Capped Chickadees
Authors: Clemmons Janine R.
Published: April 2008

There are many studies on how songbirds develop song production, but few on how songbirds develop appropriate responses to conspecific vocalizations. The black-capped chickadee, Parus atricapillus, produces a vocalization, the 'squawk', that stimulates gaping in nestlings during feeding. To determine whether nestlings gape selectively at the squawk, playbacks of several conspecific vocalizations plus a heterospecific vocalization were presented to nestlings within natural nests. A preference for the squawk did not appear until day 2-3 and then steadily increased, until by day 11-13, nestlings gaped only at the squawk. To determine whether there are constraints on which vocalization can develop as the gaping stimulus, newly-hatched nestlings were reinforced with food for gaping either at the squawk or the faint feebee, the two most common adult vocalizations at the nesting site. Regardless of reinforcement, nestlings gaped most frequently at the squawk. In addition, after the first few days posthatch, nestlings became as responsive to a third, unreinforced, heterospecific vocalization as to the squawk. The responsiveness to the heterospecific vocalization coincided with the expanding range of auditory sensitivity that occurs at the same age during passerine development. Thus, while field observations show that nestlings gape mostly to the squawk relative to other parental vocalizations, experimental evidence indicates that there is not an exclusive link between the signal (squawk) and its response (gaping), especially during the first week posthatch when parents use the signal most frequently. Rather, an effectively selective response may be achieved redundantly by a variety of factors. Possible factors that are discussed include matching acoustic structure to nestling perceptual biases and the behavior
The Selfish Crouton
Authors: Fels Daniel , Ap Rhisiart Alun , Vollrath Fritz
Published: April 2008

We studied predator prey interactions on a model system with gulls as predators and bread croutons as prey. The advantage to prey grouping appeared even at low numbers of prey and high predator density. Moreover, individual predators gained by preying upon a group rather than on a solitary prey. Rate of predation was the same for homogeneous (uni-coloured) and heterogeneous (multicoloured) groups of croutons.