bluuebunny/crossref_metadata_2025 huggingface dataset:
A Failure to Demonstrate Host Imprinting in the Cuckoo (Cuculus canorus) and Alternative Hypotheses for the Maintenance of Egg Mimicry
Authors: de L. Brooke M. , Davies N. B.
Published: May 2010

The cuckoo Cuculus canorus is divided into various gentes, each laying a distinctive egg and favouring a different species as host. It has long been assumed that the gentes remain distinct because female cuckoos lay the same egg‐type as their mother and prefer the same host, developing this preference by imprinting on their foster parents. We tested whether imprinting occurred by laboratory experiments with 7 cuckoos originating from reed warbler Acrocephalus scirpaceus nests. Two were transferred soon after hatching to robin Erithacus rubecula nests and were raised by robins, while the other five were raised by reed warblers. When about 12 d old, the nestling cuckoos and their foster parents were transferred from the wild to aviaries, where the fosterers continued to raise the cuckoos to independence. The fosterers were then released and the cuckoos retained and presented, at one and two years of age, with a behavioural choice between robins and reed warblers. None of the cuckoos (five females and two males) displayed a consistent preference for the host that reared them even, in the case of females, after oestradiol implantation. We discuss the inadequacies of our experiment and present data on cuckoo egg types to test whether natal philopatry might be sufficient to maintain the gentes. We suggest that mitochondrial DNA studies, now underway, will help to resolve the issue.
The Social System of a Communal Breeder, the Bay‐winged Cowbird Molothrus badius
Authors: Fraga Roswndo M.
Published: May 2010

Molothrus badius (bay‐winged cowbird), an icterine blackbird with cooperative breeding, shares behavioural and ecological characteristics with other communal nesters: it is sedentary, has a high annual survival rate (76.2%) and a strong nest‐site tenacity (mean breeding dispersal of 41.9 and 89.4 m for males and females). Behavioural data, including collective agonistic displays, suggest group territoriality.

Before egg hatching most breeders occurred as single pairs showing territorial behaviour (82% of nests), and nesting was usually solitary (distances to nearest nests of 25–103 m). Most breeders were apparently monogamous, with a 2.5% incidence of extrapair copulations in the territory during clutch formation. During the nestling stage one to four helpers occurred at 95% of M. badius nests. Most helpers were 1–2 years old, but older breeding adults (mostly males) that failed to rear their own offspring helped at the end of the season. The number of helpers increased (up to 4) with nestling age. Helpers were also recruited during the postfledging period, and group size reached up to 10 adults at this stage.

Helpers mobbed predators and brood parasites, and provided 35% of the nestling food. Provisioning rate was positively and significantly correlated with number of helpers, although age of nestlings was the best predictor of overall food delivery rate. The helping system was almost obligate and productivity comparisons between nests with/without helpers are not possible. Data suggest that helpers increased the breeding success per nest. The correlation between the provisioning rates of parents and helpers was negative but non‐significant.

In 18% of nests 3 to 4 individuals were present before the nestling period, including cases of apparently polyandrous trios and one case of joint nesting by two pairs. Within Brown's (1987) categories of social organization M. badius is mainly group territorial with plural nesting. Habitat requirements of M. badius are wide and nest sites do not appear to limit breeding. Kinship plays a role in the social system, as 9 of 12 helpers marked as nestlings helped their parents.
Operational Sex Ratio and Individual Mating Frequencies in Two Bushcricket Species (Orthoptera, Tettigonioidea, Poecilimon)
Authors: Heller Klaus‐Gerhard , von Helversen Dagmar
Published: May 2010

During mating the male bushericket transfers a large spermatophore which is consumed by the female after copulation. Such a ‘nuptial gift' is likely to have strong effects on the mating frequency of both males and females and thus on the operational sex ratio (OSR): For the male a longer time period will be required in which he is prevented from further matings. For the female consumption may be advantageous increasing interest in matings.

To quantify these effects field studies were carried out on two species of the genus Poecilimon. Both species differed widely in the mean number of matings observed per day (19% of all females in P. veluchianus compaied to 42% in P. affinis; Fig. 2) and thus in the distribution of female mating intervals (P. veluchianus 2 days, P. affinis 1 day (modes); Fig. 3). Separate experiments on the minimum male mating interval and the spermatophore weight also revealed distinct differences: the mean spermatophore weight was 26% of the male body weight in P. veluchianus and 15% in P. affinis (Fig. 6). Accordingly the refractory period was longer in P. veluchianus; 3 days after a previous mating nearh all males were ready to remate, compared to 2 days in P. affinis (Fig. 5). These differences, however, compensated one another in that the amount of spermatophylax material transferred per day was very similar in both species in relation to female body weight.

Using data on female mating frequency per day and male remating ability, an upper estimate for the OSR was calculated. A lower limit for the OSR was given taking into account the most frequent female mating interval (big. 7). In both species the OSR remained relatively constant for large parts of the season. The medians (upper/lower estimate for the ratio males to females ready to mate: 2.95/1.19 in P. veluchianus; 2.22 0.88 in P. affinis) were very low, comparable to that in explosive breeding frog species. Thus in the bushcricket mating system, females may be able to demand large male mating efforts so that the operational sex ratio can come close to unity.
Male‐female Parental Roles in Sarotherodon galilaeus (Pisces: Cichlidae)
Authors: Schwanck Erkki , Rana Krishen
Published: May 2010

Sarotherodon galilaeus is a predominantly biparental, sexually monomorphic mouthbrooder. 15 spawnings of pairs in the weight range 150–450 g were observed in aquaria. Only clutches of females larger than 320 g were reared jointly; with those of smaller females, the first fish to pick up eggs brooded alone, while the comparatively few eggs left for the second fish were invariably eaten. The latency after which eggs were picked up increased with the duration of spawning and indirectly with fish size. This increase was larger in males than in females, so large males started to collect eggs later than their mates. In small pairs (female weight < 200 g), by contrast, the male would pick up eggs first and carry them alone. This is the case in a smaller congeneric species, S. melanotheron, indicating that the apportioning of broodcare is based on a unitary, size‐dependent mechanism among Sarotherodon. Yet picking‐up order was not entirely determined by these equations. Some fish did not show any reaction towards the eggs and occasionally males became care‐givers despite expected longer latency, seemingly because of aggressive dominance.
Aggressive Thresholds of Male Pacific Treefrogs for Advertisement Calls Vary with Amplitude of Neighbors' Calls
Authors: Rose Gary J. , Brenowitz Eliot A.
Published: May 2010

In breeding choruses, male Pacific treefrogs (H. regilla) produce advertisement and encounter calls. The role of each call type in establishing intermale spacing patterns was investigated by playing back, at various amplitudes, recordings of these vocalizations to resident males. The aggressive threshold of a male for each call type was defined as the lowest amplitude of playback that elicited encounter calls. Pacific treefrogs consistently had lower aggressive thresholds to playbacks of encounter calls than to playbacks of advertisement calls. Aggressive thresholds to playbacks of advertisement calls were positively correlated with the maximum amplitude of the advertisement calls of neighboring males, as measured at the position of the focal male.
Aborted Polygyny in the Lesser Kestrel Falco naumanni (Aves, Falconidae)
Authors: Hiraldo Fernando , Negro Juan José , Donázar José Antonio
Published: May 2010

We observed three polygynous trios (one male and two females) in a colony of lesser kestrels in southern Spain. All these trios broke up before egg‐laying because the secondary female deserted and paired with another male. The time spent by the bigamous males with the female at the colony, the copulation rates, and the mate‐feedings, were always lower for the secondary females. Primary females received levels of investment similar to that obtained by females paired with monogamous males. Aggressions between the two females paired with the same male were frequent. Polygyny in the lesser kestrel might be favoured by a female biased sex‐ratio, and maintained because bigamous males and secondary females can get some benefits, independently of the final success of the breeding attempt.
Factors Influencing Leadership: A Study of Goose Families (Anser indicus)1)
Authors: Lamprecht Jürg
Published: May 2010

Starting from the proposition that leadership in animal groups is closely related to proximity maintenance between members, the relative contributions to mutual proximity (approach/leaving index) of parents and offspring were determined for 29 semi‐captive bar‐headed goose families (Anser indicus) in the context of undisturbed feeding. Up to 6 d of age goslings contributed more, when older than 10 d less than their parents to proximity. The percentage of following by parents was negatively related to goose density, and positively to the frequency of defence when offspring were very young, and to brood size when offspring were older. The results are compared with opposite findings in monkeys and explained in terms of likely benefits of leaving and following. Two general characteristics of group leaders (competence or need of support) are suggested.
Behavioural Variability and Development of Cataglyphis cursor Ant Workers (Hymenoptera, Formicidae)1)
Authors: Retana Javier , Cerda Xim
Published: May 2010

Variability and development of behaviour among Cataglyphis cursor ant workers was analyzed, after identifying each member of the studied nests by individual marking. Behavioural differences between workers of the same nest were considerable, even when they were assigned to the same behavioural class defined with multifactorial analysis. Workers' behaviour also changed considerably over short‐time intervals, for example from one day to another.

Behavioural development was very variable. Only ⅓ of the workers followed the classical age polyethism, while the remainder showed stable behaviour or irregular variations from the expected scheme.
Maternal Behaviour and Nest Recognition in the Subsocial Earwig Labidura riparia Pallas (Dermaptera: Labiduridae)
Authors: Radl Ruth C. , Linsenmair K. Eduard
Published: May 2010

Maternal behaviour in Labidura riparia includes care for eggs and for newly hatched larvae. Females provide their young with food and defend them (e.g. against conspecifics). Foraging females have to leave their nest and must find their way back to the brood chamber. Several active brood chambers can be situated in close vicinity in the field. This could cause identification problems. We demonstrate that females are unable to distinguish own from alien offspring. They discriminate, however, their own brood chambers from alien nests by individual‐specific recognition pheromones (discriminators) produced by the female and transferred to the nest substratum. Thus brood care is reliably restricted to the own progeny. The larvae leave the nest 2–5 d after hatching. After the first excursion the larvae do not return to their mother's nest.
Development of Social Structure in a Captive Colony of the Common Vampire Bat, Desmodus rotundus
Authors: Park Shi‐Ryong
Published: May 2010

The development of social structures of the vampire bat (Desmodus rotundus) was studied in small groups in a captive colony over a period of 30 months. The membership of individuals in the main group and the development of group formation were evaluated by the coherence index. The main group of the vampire colony consisted of several adult females, their infants and one harem male. All members of the main group showed relatively high coherence indices, while the coherence index of adult males, except the harem male, was 0. The females and young in the main group formed a very stable group in comparison to the adult males. The young males left the main group at 20–27 months of age and formed temporary bachelor groups. The harem males changed during the study in the period from 1 to 20 months. They exhibited territorial behaviour and made vigorous attempts to approach the main group within the bounds of their roosting areas, whilst also keeping out intruders.
Black Coots (Fulica atra; Aves, Rallidae) Supplanting Conspecifics from Foraging Sites
Authors: Amat Juan A. , Obeso J. Ramón
Published: May 2010

When individuals forage in groups they may acquire information on the quality of feeding sites from observations of the activities of other individuals. During the non‐breeding season, black coots (Fulica atra) directed attacks at conspecifics with the main purpose of supplanting them from foraging sites. By supplanting, coots did not increase the amount of food ingested relative to birds feeding undisturbed, but instead reduced the costs associated with obtaining food by spending less time foraging by the more costly method. The rate of food intake of supplanted coots was lower than that of undisturbed birds, probably not only because following the displacement they moved away, but also because immediately after moving the time spent feeding on plants brought to the surface after each dive was shorter, although they dived with the same frequency as undisturbed coots did. This indicates that supplanted coots were displaced to sites of lower quality. Probably, the extent to which supplanting was performed was related to a decline in food quality arising from dry conditions.
Territorial Significance of Scent Marking during the Non‐mating Season in the Aardwolf Proteles cristatus (Carnivora: Protelidae)
Authors: Richardson Philip R. K.
Published: May 2010

Patterns of scent‐marking by male and female aardwolves during the non‐mating season in the northern Cape Province are described. The distribution of scent marks conforms to predictions for marks being used as territorial advertisements. Scent marks were concentrated around territory borders and were deposited at increasingly higher densities in smaller territories. The data are used to re‐examine existing hypotheses as to how scent marks function in territory maintenance. Scent marks provide an olfactory association between the resident and the defended area, but I suggest that the message provided by this association may depend heavily on territory size, the frequency of territorial encounters and the defensive behaviour of the resident. The greater the territory size and hence the difficulty in monitoring intrusions, the greater the threat transmitted by scent marks needs to be. In most territorial carnivores, scent marks may be interpreted by intruders as a threat of immediate physical attack if encountered by the resident. Thus scent marks help to maintain, but cannot ensure, territorial integrity in the temporary absence of the resident.
Route‐based Visual Information has Limited Effect on the Homing Performance of Red Squirrels, Tamiasciurus hudsonicus
Authors: Bovet Jacques
Published: May 2010

The role of route‐based visual information in the homing behavior of red squirrels (Tamiasciurus hudsonicus) was assessed in an experiment contrasting the homing performance of 8 squirrels that could see the landscape during displacement and that of 8 squirrels that could not. Availability of route‐based visual information improves the accuracy of homeward orientation but is of no use for the animals to assess distance to home. These findings are congruent with the “critical‐distance model” (Bovet 1984, 1987) which implies that choice of direction and estimation of distance are independent processes in the homing performance of untrained animals.
Sex Differences in Giraffe Feeding Ecology: Energetic and Social Constraints
Authors: Young Truman P. , Isbell Lynne A.
Published: May 2010

Sex ratios of giraffe groups differ in different habitats, with open vegetation having female‐biased groups, and tall, thick vegetation having male‐biased groups. On a ranch in south‐central Kenya, we quantified habitat differences of male and female giraffe groups and showed that the preference for open habitats by female groups was limited to groups with young. We suggest that this difference is due to the avoidance of predators of young giraffes. We also showed that rates of giraffe feeding peaked at intermediate feeding heights equal to approximately 60% of adult giraffe height. In the dense habitats with a variety of tree heights used by male groups and female groups without young, both male and female giraffes fed most at heights where they could feed fastest. However, in the open habitats used by female groups with young, females fed mostly at heights below optimum because these habitats are dominated by short food plants. On the other hand, the dominant males accompanying these female groups fed at heights above optimum on rare tall trees, possibly to increase intrasexual vigilance. Apparently, both male and female giraffes sometimes forfeit feeding efficiency tor short‐term reproductive gains.
Colony Energy Requirements Affect Response to Predation Risk in Foraging Bumble Bees
Authors: Cartar Ralph V.
Published: May 2010

Foraging animals must often be sensitive to the dual risks of predation and energy shortfall, and should devalue risk of predation as risk of starvation increases. This study examines whether the probability of colony‐level energy shortfall influences the predation risks taken by individual foraging bumble bees (Bombus occidentalis) in confined colonies as they collected sugar water from artificial flowers. Before each trial, colony energy stores were manipulated by enhancing or removing the contents of the colony's honey pots. Feeding bees were significantly more likely to flee from an artificial predator model (a black styrofoam ball moved overhead) when their colony's energy stores were enhanced, relative to when their colony's energy stores were depleted. Despite their defensive stings and aposematic coloration, bumble bees are more likely to accept “risky” foraging situations when the energy needs of their colony are increased.
Why is the Eye‐like Spot of the Oyanirami Fish Coreoperca kawamebari Located near the Real Eye?
Authors: Kohda Yasutoshi , Watanabe Munetaka
Published: May 2010

In agonistic encounters an oyanirami (Coreoperca kawamebari) displays laterally to a rival. The lateral pattern is thought to have a threatening effect, eliciting aggressive reactions. A conspicuous eye‐like spot near the real eye is a main component of the pattern and is almost a key stimulus releasing aggressive actions of rivals; it has been shown, however, that the position of the spot has no connection with this effect. In the present study, video‐taped bites on two dummies were examined, one with the normal aggressive pattern and one with an artificial posterior‐spotted pattern. The natural eye‐like spots deflected attacks from the real eyes, but the artificial spots further from the real eyes did not. Only the nearby eye‐like spots can preserve the real eyes from rival attacks.
Experiments on Winter‐site Attachment in Young Dark‐eyed Juncos
Authors: Nolan Val , Ketterson Ellen D.
Published: May 2010

Site attachment in young birds has sometimes been considered to take place during a sensitive phase as the result of an imprinting‐like process. We conducted two four‐year‐long experiments on winter‐site attachment in young migratory dark‐eyed juncos (Junco hyemalis). In both, we caught birds over a range of dates, displaced them to large outdoor enclosures, and released them near the end of winter. In the first experiment, release was at the capture site and all returns next winter were to that site. The return rate did not vary with date of capture and confinement; therefore attachment could have been completed either before capture or after release. The absence of returns to the confinement site suggests that attachment to a place requires that the individual live free there. In the second experiment, release was at the confinement site, and many subjects remained there, probably until they migrated northward. Returns next winter were to both the capture site (the majority) and the confinement‐release site. The fact that a few juncos formed a bond to the confinement‐release site in this experiment reinforces the view that living free is necessary for site attachment. Individuals caught and confined earlier in winter tended to be less likely to return than those caught later. The distribution of returns according to date of capture indicates that attachment was completed at different dates in different subjects, which is not consistent with imprinting during a clearly defined sensitive period. However, young juncos hatch and migrate at various dates. Therefore our experiment does not rule out the existence of a brief sensitive phase for site attachment, its dates varying among individuals because age and/or timing of migration vary.
Homing in the Digger Wasp Bembix rostrata (Hymenoptera, Sphecidae) — Release Direction and Weather Conditions
Authors: Schöne Hermann , Tengö Jan
Published: May 2010

Wasps were released 500 m S, NW and NE of the nest aggregation. Approaches were over grassland, bush with spinneys, and pines. The sun was visible at releases, but often became concealed by clouds.

Homing times are positively correlated with sun cover times. The regression lines indicate a difference between S wasps and NW/NE wasps (S 26, NW 57, NE 66 min). NW wasps appeared to home somewhat better than NE wasps if only the fastest homers were considered.

Results are interpreted in terms of the known concepts of sun compass and landmark orientation in relation to familiarity with the release area.
Female Preferences Based on Male Quality in House Mice: Interaction between Male Dominance Rank and t‐Complex Genotype
Authors: Coopersmith Carol B. , Lenington Sarah
Published: May 2010

Considerable evidence indicates that female house mice (Mus domesticus) prefer dominant over subordinate males as mates. In addition, male genotype at the t‐complex seems to be an important characteristic used by females in mate choice. Specifically, female mice that carry a t‐haplotype at the t‐complex prefer +/+ over +/t males as mates. The purpose of the present study was to examine the relative contributions of male dominance rank and male t‐complex genotype to female mating preference when both factors were systematically varied.

We tested females of three genotypes (+/+, +/t, and t/t) in a preference apparatus using pairs of stimulus males varying in relative dominance status and t‐complex genotype. In general, when given the choice, females preferred dominant over subordinate males regardless of the male's t‐complex genotype. The preference for dominant males was manifested when both stimulus males were of the same t‐complex genotype but differed in dominance rank. In addition, when forced to choose between a dominant +/+ and subordinate +/t or between a dominant +/t and subordinate +/+, females continued to prefer the dominant male. Preference for dominant males was independent of female genotype. Only when both males were dominant but differed in t‐complex genotype (i.e. one male was +/+ and the other +/t) or when males were unranked (i.e. had not been used in aggressive encounters to determine dominance rank) did females carrying t‐haplotypes manifest preferences for +/+ males. Quite unexpectedly, when both males were subordinate but differed in t‐complex genotype, preferences of all females shifted in the direction of the +/t male.

It is not clear from present data whether the propensity of females to give greater weight to male dominance rank than to t‐complex genotype in choosing mates results in greater fitness. However, if these trends are found in natural populations, it would indicate that the role of mating preference in regulating the frequency of t‐haplotypes in wild populations is less straightforward than had been previously thought.
Agonistic Tactics and Size Asymmetries between Opponents in Blattella germanica (L.) (Dictyoptera: Blattellidae)
Authors: Rivault Colette , Cloarec Ann
Published: May 2010

In this paper we investigated the influence of size differences between opponents on the occurrence of different agonistic attack and response tactics displayed during encounters between Blattella germanica (L.) cockroaches of all developmental stages, competing for a limited food source. The two main results were: 1) attack and response tactics varied during development and 2) size asymmetries between contestants influenced agonistic tactics. Developmental stage of initiator influenced the frequency distribution of the three types of attack patterns (Bite, Kick and Jump) and of the four types of response patterns (Retaliation, Escape, Resettle and No Response). The proportion of kicks increased gradually with developmental stage of the initiator whereas the proportion of bites declined during development. In addition, cockroaches adapted their attack tactics to the developmental stage of their opponent. Similarly the response displayed varied in relation to the developmental stage of the attacked individual, the developmental stage of the initiator and the type of attack displayed. During an interaction, animals appeared to be able to evaluate the relative size of their opponent and to evaluate the consequences of the behavioural pattern they displayed. Larger animals tended to minimize the intensity of the agonistic act they initiated. Escalation in interactions was rare and smaller individuals tended to escape when attacked by larger ones. Wrong estimations of the relative size of opponent, when a smaller animal retaliated after being attacked by a larger animal or when a larger animal fled after being attacked by a smaller one, represented only 6% of the records.
The Organization of Song Repertoires in Song Sparrows: Themes and Variations
Authors: Podos Jeffrey , Peters Susan , Rudnicky Tamia , Marler Peter , Nowicki Stephen
Published: May 2010

Although songtypes are generally considered to be important functional units in birdsong, they have not been well‐characterized in terms of within‐ and between‐songtype variation. We analyzed the song repertoires of 12 adult male song sparrows (Melospiza melodia) from a population in New York. We identified minimal units of production (MUPs), and calculated the degree to which song variants within a bird's repertoire were similar to each other based on an analysis of MUP sharing. Using statistical techniques from numerical taxonomy, we assessed how song variants clustered into songtypes, and we derived quantitative measures of within‐songtype and between‐songtype similarity. We found that birds produced a limited number of songtypes, but constantly produced new song variants within the framework of these types. Most song variants were produced very rarely; over 43% of song variants were produced only once. Repertoires differed in the degree of between‐songtype similarity and in the number of songtypes defined, but there was comparatively less variation in within‐songtype similarity. Between‐songtype similarity and repertoire size were positively correlated. We argue that song sparrow songtypes are probabilistic units of song production, and discuss the functional and evolutionary implications of having vocal motor patterns organized in this way.
Differential Probability of “Coproduction” in Two Species of Macaque (Macaca tonkeana, M. mulatta)
Authors: Petit Odile , Desportes Christine , Thierry Bernard
Published: May 2010

This study aimed to assess the conditions under which monkeys might produce common effects in an instrumental task. One group of Tonkean macaques (Macaca tonkeana) and two groups of rhesus macaques (M. mulatta) were given series of tests in which food incentives were placed under stones of various weights. In the Tonkean group, the simultaneous action of two subjects in moving the same stone was a relatively frequently occurring event: coaction was more effective than individual action for moving heavy stones; however, there were no signs of coordination among partners and no improvement through learning. In rhesus groups, instances of coaction were extremely rare, and rates of agonistic interactions were higher than in the Tonkean group. It is suggested that “coproduction” represented an emergent phenomenon resulting from social interactions and, as such, was dependent on the level of interindividual tolerance.
Cooperation and Prey Capture Efficiency in a Social Spider, Anelosimus eximius (Araneae, Theridiidae)
Authors: Pasquet Alain , Krafft Bertrand
Published: May 2010

We studied the efficiency of the hunt and the characteristics of cooperation during the prey capture in a social spider Anelosimus eximius.

Two natural types of prey of roughly the same length (20 mm) were used: grasshoppers (Orthoptera) and moths (Lepidoptera); 128 tests were made on 14 colonies, the smallest with 20 and the largest with 1,700 individuals. Test times were 12.00 h, defined as an inactive period for the spiders and 18.00 h, defined as an active period.

Overall capture rate of intercepted prey was 66%: it was higher in large colonies or at 18.00 h, when more spider alerts were triggered by the struggling prey. Characteristics of cooperation during capture did not vary with colony size.

Capture rate was higher for grasshoppers than moths (73%‐58%) in spite of similar number of alerts (76%‐87%); so moths must have been more difficult to capture. For both prey types, large colonies capture more rapidly and so had advantages in terms of time gain.

We showed that cooperation depended on prey type: more spiders mobilised to attack moths and attack was faster than on grasshoppers. This may be interpreted as an adaptive response of the group to the prey type.
Territory Quality in Mountain Reedbuck (Redunca fulvorufula chanleri): Distance to Safety
Authors: Dunbar R. I. M. , Roberts S. C.
Published: May 2010

Reedbuck are heavily dependent on cover as a means of evading predators, and Howard (1986a) suggested that males defend cover‐abundant habitat in order to maximize access to receptive females which congregate in these areas. We use a measure of female preference for individual territories, and variations in territory size and quality to test this hypothesis in Chanler's mountain reedbuck (Redunca fulvorufula chanleri). Although the amount of cover within each territory did appear to be important, the height of available slope predicted female preference most precisely. It is concluded that, under certain conditions, the extent of available slopes for predator evasion may be a more appropriate indicator of territory quality.
Visual Assessment of Relative Body Size in a Cichlid Fish, the Oscar, Astronotus ocellatus
Authors: Beeching Simon C.
Published: May 2010

In cichlid fishes, fighting ability, success at nest defense, and fecundity are all positively correlated with body size. Selection should therefore favor the evolution of strategies for the assessment of relative body size during intraspecific interactions. The effect of relative body size on agonistic behavior in the oscar (Astronotus ocellatus) was tested using dummies. As predicted by game theory models, attack was strongly correlated with the size of the dummy relative to the subject. The most intense aggression occurred when dummy size was approximately 75% of subject size. These data support the prediciton that perceived body size asymmetries are important determinants of agonistic behavior in these fishes. Further, the results suggest that oscars can visually assess relative body size, and may estimate relative fighting ability without tests of strength. Subject size was positively correlated with intensity of aggressive behavior. Attack and display frequencies were positively correlated with a subject's body size, while latencies to approach and attack dummies were negatively correlated with subject size.
Special Relationships between Female Asian Elephants (Elephas maximus) in Zoological Gardens
Authors: Garaï Marion E.
Published: May 2010

Social relationships between female zoo elephants were analyzed on three different zoo groups. Interactions were defined as either affiliative or agonistic. The most frequent interactions were found to be touching of the partner's mouth, genital sinus, face and trunk. The calf was the individual involved in most social interactions. Placing the trunk tip into the partner's mouth is a well known behaviour, the correlation between this behaviour and aggression was analyzed and a further function is suggested. Aggressive behaviour was analyzed and the hypothesis derived that rank order has to be established and is flexible in a non‐kin group. The hypothesis that Asian elephant females may form special relationships was tested and confirmed. The following behaviour patterns were determined as indicators of a special relationship: Spatial proximity, partner‐specific reactions to arousal and to vocalizing, and omission of agonistic behaviour. An experiment confirmed the hypothesis that the removal of one member of a special relationship from the enclosure would elicit more arousal behaviour in the respective partner.
Ontogeny of Time Allocation in Black‐tailed Prairie Dogs
Authors: Loughry W. J.
Published: May 2010

The ontogeny of time allocation was studied in a field population of black‐tailed prairie dogs, Cynomys ludovicianus. Pups first emerged from their natal burrows in late May. All individuals in the population, including all pups, were observed for 12 weeks following this emergence. Both cross‐sectional and longitudinal analyses of ontogeny revealed considerable age differences. Upon first emergence, pups were extremely wary and spent most of their time vigilant and little time feeding. As pups aged, they increased time spent feeding and decreased time spent vigilant. Male and female pups behaved similarly. Pups differed from adults in their time allocation patterns and these differences changed as pups aged. Pups were initially more vigilant and fed less than adults, but became less vigilant than adults as the summer progressed. Yearlings behaved similarly to adults. Possible intrinsic (e.g., pup age and weight) and extrinsic (e.g., weather conditions, microhabitat location and coterie composition) influences on time allocation by pups were also examined. In general, extrinsic influences appeared to have more impact on pup behavior than intrinsic ones, suggesting that time allocation by pups may be largely context‐dependent. Overall, the considerable number of age differences argues for more consideration of ontogeny in models of antipredator behavior.
Is the Tonal Quality of Birdsong Learned? Evidence from Song Sparrows
Authors: Nowicki Stephen , Marler Peter , Maynard Alicia , Peters Susan
Published: May 2010

Song sparrow (Melospiza melodia) songs are composed largely of pure‐tonal sounds. This paper investigates the role that learning plays in the development of the tonal structure of song sparrow songs, as well as the role that tonal quality plays in determining the suitability of songs as models for learning. 20 birds were trained with both normal pure‐tonal songs and modified songs that included harmonic overtones. The harmonic‐modified songs were obtained from birds singing in a helium atmosphere, the result of which is to perturb vocal tract resonances and thus alter a song's tonal quality. Subjects learned equally well from normal and harmonic models. Birds that learned material from harmonic models reproduced some of this material with harmonic overtones, but the majority of notes learned from harmonic models were subsequently reproduced as pure‐tonal copies. Thus, the tonal structure of songs does not influence young song sparrows in their selection of song models, but there is a strong tendency to reproduce songs in a pure‐tonal fashion, even if learned from harmonic models.
Castration Lowers Aggression but not Social Dominance in Male Haplochromis burtoni (Cichlidae)
Authors: Francis Richard C. , Jacobson Ben , Wingfield John C. , Fernald Russell D.
Published: May 2010

Adult males of the African cichlid fish Haplochromis burtoni are either territorial or nonterritorial. In nature and aquaria, only territorial males breed and they have markedly more developed testes than do nonterritorial males. Territorial males are clearly dominant over nonterritorial males of the same age and size, and also exhibit higher levels of aggression. In this study, territorial males were gonadectomized in order to assess the effects of lowered androgen levels on their aggression and dominance status. Completely castrated males showed a pronounced reduction in both testosterone and 11‐ketotestosterone, as well as significantly lower aggression scores than sham‐operated males. Partially castrated males (> 0.005 g gonadal tissue remaining at autopsy) exhibited intermediate levels of both androgen levels and aggression. Surprisingly, in dyadic encounters with normal nonterritorial males of the same size, castrated territorial males retained their dominance despite decreased androgen levels and aggression.
Interspecific Response to Playback of Bird Song
Authors: Møller Anders Pape
Published: May 2010

Responses to bird song have usually only been studied at the intraspecific level. I experimentally tested whether playback of the song of the black wheatear Oenanthe leucura in an area in S Spain resulted in responses from conspecifics as well as heterospecific birds by comparing the numbers of individuals singing before and after playback. The number of singing male black wheatears increased considerably, but also the number of singing males of five other passerine species increased significantly. The heterospecific response to playback may be due (1) to interspecific territoriality, (2) to black wheatear song signalling the absence of predators, or (3) to heterospecifics confusing the species‐identity of the singer. The second alternative is considered more likely, since an ecologically wide array of species increased their song rate following playback. The conspicuous dawn (and dusk) chorus of bird song may be augmented by social facilitation due to the singing of conspecifics as well as heterospecifics.
Social Behaviour and Cooperative Breeding in Arctic Foxes, Alopex lagopus (L.), in a Semi‐natural Environment
Authors: Kullberg Cecilia , Angerbjörn Anders
Published: May 2010

Most canid species show cooperative breeding at least occasionally. The helper‐at‐the‐den system, when extra adults serve as helpers by feeding and guarding the cubs of an alpha pair, has been observed but not studied in any detail in wild Arctic foxes (Alopex lagopus). During a 3‐months study of arctic foxes in two enclosures of 4 ha each, we measured the social behaviour during the reproductive season. Older foxes dominated younger ones and males dominated females of the same age. A litter with one surviving cub was born in one enclosure. The alpha male increased his rate of urine marking and barking and fed the alpha female both before and after the birth of the litter. However, about 10 days after the birth, the alpha female died. The cub was fed by his putative father, his sister and his brother (both one year old). The one year old female increased her rate of territorial defence, measured as urine marking and barking, when the mother died. The subordinate females were probably suppressed from breeding by the high aggression levels and territorial defence of the dominant females in each enclosure. The dominant female in the second enclosure came into heat after the death of the alpha female (her mother) in the first enclosure. These changes in behaviour can probably be explained by sexual inhibition by the alpha female while she was present. The significance of territorial defence and dominance, inbreeding avoidance, sexual suppression and evolution of helping behaviour are discussed.
Intentional Icons: Towards an Evolutionary Cognitive Ethology
Authors: Bekoff Marc , Allen Colin
Published: May 2010

In most species in which social play has been observed, play‐soliciting signals have evolved. These social signals appear to be important in communicating play intention. Here, using the work of Ruth Millikan as a working guide and canid play bows as an example, we argue that (i) some play signals may be simple “intentional icons” and (ii) senders and receivers are “cooperating devices,” in that the disposition of senders to produce play‐soliciting signals and the disposition of receivers of play signals to respond appropriately to play invitations, have evolved together. Millikan's views of social communication are difficult to render and are virtually untested. However, her stance, while philosophically controversial, is somewhat consistent with early ethological views of social communication. Thus, in combination with classical ethological positions, Millikan's position could serve as a useful guide not only to inform and motivate future empirical research in cognitive ethology, but also to stimulate ethologists to reconsider, in innovative ways, nonhuman animal cognition. To reject the empirical utility of Millikan's theory because of its difficulty or on philosophical grounds would be premature and would represent a confusion of empirical with philosophical issues.
Differences in Neophobia between Naive Song and Swamp Sparrows
Authors: Greenberg Russell
Published: May 2010

I measured feeding neophobia in song (Melospiza melodia) and swamp (M. georgiana) sparrows. The experiment had a counter‐balanced design with each species divided into two rearing groups and each exposed to a different set of six objects. I tested sparrows at two months of age by measuring their latency to feed at cups placed at familiar and novel objects. These tests were repeated at six months using an additional four novel objects. In comparison with song sparrows, juvenile swamp sparrows had a significantly and consistently lower latency to feed at novel objects. I found this difference in older birds as well. Feeding latencies at familiar objects were statistically indistinguishable between species. These results suggest that song sparrows are more neophobic than swamp sparrows. I obtained opposite results from similar experiments conducted in the field and using wild‐caught birds in captivity. Greater neophobia in wild swamp sparrows may be a consequence of differential experience between the two species in nature. Differences found between hand‐raised song and swamp sparrows is one of the first demonstrations of interspecific differences in neophobia under similar and controlled rearing conditions. A possible adaptive explanation is that, typically, juvenile swamp sparrows are reared in a simpler, more predictable and hence safer environment and may not require the protection of an aversion to novelty.
Migratory Orientation: Magnetic Compass Orientation of Garden Warblers (Sylvia borin) after a Simulated Crossing of the Magnetic Equator
Authors: Wiltschko Wolfgang , Wiltschko Roswitha
Published: May 2010

Since the birds' magnetic compass works as an inclination compass using the axial course of the magnetic field lines and their inclination, transequatorial migrants have to reverse their reaction with respect to the magnetic field after crossing the magnetic equator. Garden Warblers, long distance migrants breeding in Europe and wintering in tropical and southern Africa, were tested during autumn in the local geomagnetic field on the northern hemisphere. The experimental group was exposed to a field with horizontal field lines, simulating equator crossing, at the beginning of October; afterwards the birds were tested in the local geomagnetic field again. While the controls showed southerly tendencies during the entire season, the experimentals reversed their directional tendencies after staying in the horizontal field and now preferred northerly directions. In a field of the southern hemisphere, this preference corresponds to a southern course which would have meant the continuation of their migration flight.
You Can Get There from Here: Responses to Simulated Magnetic Equator Crossing by the Bobolink (Dolichonyx oryzivorus)
Authors: Beason Robert C.
Published: May 2010

The avian magnetic compass works as an inclination compass. Instead of using the polarity of the magnetic field to determine direction, birds use the inclination of the dip angle. Consequently, transequatorial migrants have to reverse their response to the magnetic compass after crossing the magnetic equator. When confronted with an artificial magnetic field that reverses the vertical component of the magnetic field, migrants such as the bobolink reverse their headings relative to magnetic north even in the presence of visual cues such as stellar patterns. Bobolinks, which breed in temperate North America and winter in temperate South America, were tested in a planetarium under fixed star patterns in a series of magnetic fields incremented each night from the natural field in the northern hemisphere through an artificial horizontal field to an artificial southern hemisphere magnetic field. The birds maintained a constant heading throughout the experiment and did not reverse direction after the simulated crossing of the magnetic equator as previous experiments predicted. In nature, this response would have meant continuation of their migration flight across the equator and into the opposite hemisphere. The switch from “equatorward” orientation to “poleward” orientation is probably triggered by experience with a horizontal magnetic field and/or visual cues. The ability to maintain an accurate heading while crossing the magnetic equator may be based on the use of visual cues such as the stars.
Dart‐poison Frogs and the Control of Sexual Selection
Authors: Summers Kyle
Published: May 2010

In some species of dart‐poison frogs (genus Dendrobates), males perform parental care. Some researchers have suggested that high relative parental investment by males in these species causes sex‐role reversal. I argue here that, in general, three factors cause sexual selection: inequality of relative parental investment, variance in mate quality, and variability of parental investment. I review evidence from my previous research that contradicts the hypothesis that unequal relative parental investment can explain female mating strategies in two species of dart‐poison frogs with male parental care. I then discuss the hypothesis that variability of male parental investment has an important effect on female mating strategies in these species.