bluuebunny/crossref_metadata_2025 huggingface dataset:
Homing in the Mangrove Swimming Crab Thalamita crenata (Decapoda: Portunidae)
Authors: Cannicci Stefano , Dahdouh‐Guebas Farid , Anyona Dyane , Vannini Marco
Published: May 2010

On the Kenyan coast, Thalamita crenata confines itself to a defined system of crevices and forages, swimming in a few cm of water, within a radius of about 5 m from its shelter. A field study was designed to analyse this crab's ability to find its shelter after being moved away from it.

Crabs were displaced, being kept under water, with full vision of the sky and landscape and released 5 m away from their refuges, at a maximum depth of 50 cm. They were able to return to their shelters within 1 h and followed initial directions which were well orientated towards home. T. crenata was still well orientated and successful in returning home during nocturnal displacements and even after trials in which the landscape was altered. Only blind crabs were neither initially orientated towards home nor successful in returning within two tidal cycles of their release.

The hypothesis that this swimming crab could use orientating information obtained during the outward displacement was then tested. Specimens were dislocated following a non‐linear outward path, without vision of the surrounding landscape; other crabs were carried to a false release point and then carried in a closed container to the actual release point. Finally, three kinds of detour experiments were performed. In all these trials the directions chosen by the crabs were still clustered around the home direction and homing success was again high.

These results exclude homing mechanisms based on random search strategies or on egocentric mechanisms, such as path integration. The most probable hypothesis is that T. crenata organizes some visual cues in a map‐like arrangement and, detecting these cues from any release point within its home range, uses this map to return home.
Innate Recognition by Host Fish of their Cleaning Symbiont
Authors: Losey George S. , Mahon Jeffrey L. , Danilowicz Bret S.
Published: May 2010

Naive damselfish,Dascyllus albisella, were tested for their initial response to the Hawaiian cleaning wrasse,Labroides phthirophagus.Contrary to some current theory, some individuals, including both lab‐reared and wild‐caught fish, showed a full ‘pose’ response to visual stimuli from the cleaner without prior tactile stimulation, while others failed to show this response even after 4 d of exposure to visual and tactile stimuli. These individual differences could have resulted from innate differences or uncontrolled variables in their experience.
The Ontogeny of Antipredator Behaviour in Paradise Fish Larvae (Macropodus opercularis): The Recognition of Eyespots
Authors: Miklósi Ádám , Berzsenyi Gábor , Pongrácz Péter , Csányi Vilmos
Published: May 2010

The ontogeny of antipredator behaviour of paradise fish was examined using a simple testing method. The results showed that the ability to recognize eyespots appears in larvae between 15 and 20 days old. At the same time, two horizontally placed eyespots produced the most pronounced effect on the behaviour of the larvae. Testing different inbred strains revealed that the ontogeny of antipredator behaviour is also under broad genetic control, as the response to a model predator was strong in one strain but weak in another. The results suggest that the recognition of eyespots coincides with larvae becoming more conspicuous to predators by the appearance of pigmentation and increasing level of swimming activity (exploration).
Activity Pattern of Polecats Mustela putorius L. in Relation to Food Habits and Prey Activity
Authors: Lode Thierry
Published: May 2010

The activity pattern of polecats Mustela putorius L. was studied by radiotracking five males and four females in the wetlands of western France from Jul. 1988 to Mar. 1992. Polecats were nocturnal throughout the year with no differences between males and females. The diel activity remained moderate (31 %). Seasonal food habits were characterized by the exploitation of anurans in spring, while rodents were preyed upon from summer to winter. Seasonal changes in the activity rhythm of polecats appeared synchronized with the activity of the main prey. It is suggested that the activity patterns exhibited in different periods of the year are a result of changes in feeding tactics.
Golden‐marmot Alarm Calls. II. Asymmetrical Production and Perception of Situationally Specific Vocalizations?
Authors: Blumstein Daniel T.
Published: May 2010

Many species produce alarm calls that vary according to situation. An implicit assumption for these species is that production and perception of situationally specific alarm calls is symmetrical: perceivers respond to variation produced by signalers. The companion paper to this one (Blumstein 1995) showed that golden marmots (Marmota caudata aurea) produce variable alarm calls that vary in proportion to the degree of risk the caller perceives. Calls produced in higher‐risk situations have fewer notes than calls produced in lower‐risk situations. In this study, to determine the salience of the number of notes per call in eliciting different responses in conspecific perceivers, I played back three‐note alarm calls, eight‐note alarm calls, and the non‐alarm vocalization of a local bird to adult golden marmots. Although marmots responded differently to bird calls and alarm calls, vigilance responses to the different alarm calls were similar. Several explanations may account for the apparent insensitivity to alarm‐call variation: golden marmots may require additional contextual cues to properly interpret alarm calls, perceptual abilities do not parallel production abilities, or calls may serve a generalized alerting function.
Further Evidence of Lack of Pheromonal Inhibition among Queens of the Ant Leptothorax acervorum
Authors: Bourke Andrew F. G.
Published: May 2010

Queens in some species of ant with several queens per colony are believed to inhibit one another's fecundity pheromonally. This paper describes a repeat of an experimental test of this idea in the multiple‐queen ant Leptothorax acervorum. The three most fecund queens from a field‐collected colony were housed together in an experimental nest. This was then filmed for 10 h per day over 36 consecutive days (i.e. for 360 h in total). Over the first 12 d, all queens were present in the colony. For the middle 12 d, the two most fecund queens were removed, but were returned for the final 12 d. The queen that was observed throughout the experiment failed to show a rise in fecundity when the other queens were removed. Instead, her egg‐laying rate fell, although this drop was not significant. These results confirm previous findings that short‐term, strong pheromonal inhibition of fecundity does not occur among L. acervorum queens. The phenomena of pheromonal inhibition in other species may be a result of workers treating queens differentially in response to rapid, short‐term changes in the numbers of queens and eggs. If so, the results presented here could stem from the relative infrequency of such changes in L. acervorum.
Factors Affecting Acoustic Variation in Barbary‐macaque (Macaca sylvanus) Disturbance Calls
Authors: Fischer Julia , Hammerschmidt Kurt , Todt Dietmar
Published: May 2010

Semi‐free‐ranging Barbary macaques (Macaca sylvanus) were observed to utter distinctive calls after disturbances in the surroundings (e.g. presence of a predator, occurrence of some unusual phenomenon). These calls differed from calls given in other contexts. Most of these calls were uttered in a serial manner, some of which lasted as long as the corresponding context. The aim of this study was to determine the object‐related specificity of calls and variation of acoustic parameters within a call series. The analysis revealed that acoustic features of calls varied among contexts. Within one apparently homogeneous context, both temporal and frequency characteristics shifted gradually. Furthermore, the disturbance calls clearly differed between individuals. To examine the disturbance calls' meaning, playback experiments were conducted in which alarm calls and disturbance calls were presented. After playback of an alarm call, subjects typically showed an escape response, whereas, in response to disturbance calls, they most often scanned the surroundings. Juvenile animals generally showed stronger responses than adults.
Evidence of a Universal Perceptual Unit in Mammals
Authors: Gerstner Geoffrey E. , Fazio Victoria A.
Published: May 2010

Evidence from many studies conducted over the past century suggests that human perception is partitioned into 1–4‐s units. More recently, a similar 1–4‐s time constant has been found in non‐perceptual phenomena, i.e. movement patterns, of both human and non‐human mammalian species. Based on these findings, it appears that an evolutionarily conserved mechanism exists that segments human and non‐human mammalian motor actions into 1–4‐s units. This being the case, it is believed that the 1–4‐s segmentation seen in human perception may also occur in mammalian perception. However, it is currently impossible to determine whether both human and non‐human perception is partitioned into 1–4‐s units because the paradigms used to study the 1–4‐s unit in human perception cannot be applied to non‐human species. This study hypothesized that vigilance postures represent a paradigm that will allow such comparative work. This is based on the fact that investigators recently found that vigilant postures in humans are partitioned into 1–4‐s units, and the literature argues strongly that vigilance is largely a perceptual phenomenon. With this in mind, the current study determined whether similar vigilant postures occur in non‐human mammals and whether such vigilant postures are also segmented into 1–4‐s units. The study found that such postures averaged 2–3.5 s in primates (n = 1 species), carnivores (n = 2 species), artiodactyls (n = 3 species), and marsupials (n = 1 species). These findings support the hypothesis that perception in humans and other mammals is partitioned into units by a conserved mechanism. It is believed that vigilant postures will be an important quantifiable bioassay with which to conduct comparative studies of mammalian perception.
Ontogenetic Development of Spatial Orientation in First‐ and Second‐instar Cockroach Larvae (Blattella germanica (L.), Dictyoptera)
Authors: Dabouineau Laurent , Rivault Colette
Published: May 2010

Changes in spatial orientation related to aging were investigated during the first two instars in Blattella germanica (L). Spatial orientation was tested through shelter return under various experimental conditions in order to understand how kinesthetic path integration and visual cues intervene in the construction of this behaviour. We were able to distinguish two types of changes: experience during the first instar and maturation between instars. Young larvae need 2–3 d to develop the appropriate shelter‐return behaviour when they can only use visual cues. By contrast, they can use kinesthetic path‐integration cues efficiently to return to the shelter as soon as they hatch.
Alloparental Egg Care in the Polychaete Worm Ophryotrocha diadema
Authors: Premoli Maria Clotilde , Sella Gabriella
Published: May 2010

In the simultaneously hermaphroditic worm Ophryotrocha diadema, eggs are laid in nesting sites i.e. widenings of mucous trails built by parents. Nesting sites where eggs are present represent highly predictable places where other conspecifics, attracted by the mucous trails, tend to congregate. Care for developing embryos is associated with regular alternation of sex functions and reciprocal egg exchange between partners of the same pair. Generally both parents tend their eggs, but eggs develop equally well if they are cared for by a genetically unrelated individual (adopter). The aim of this study was to investigate the possible evolutionary significance of the adoption of neglected eggs by unpaired worms. Results of our experiments indicate that: 1. Apparently there are no direct cues (e.g. chemical) for kin recognition: cues are only indirect, i.e. only eggs located in the nesting sites elicit parental care by any worm; and 2. In a low‐density laboratory population (1 individual per 500 ml) of O. diadema, by tending eggs of whatever provenance in the nesting sites, unpaired hermaphrodites increase by 1.23 times their mating opportunities, compared with hermaphrodites not caring for eggs and seeking for a mate outside the nesting sites. In this sense, in a low‐density population, non‐parental egg attendance can be considered adaptive.
Tool Use by Spiders: Stone Selection and Placement by Corolla Spiders Ariadna (Segestriidae) of the Namib Desert
Authors: Henschel Joh R.
Published: May 2010

The corolla spider (Araneae: Segestriidae: Ariadna) of the Namib Desert gravel plains typically places seven or eight stones in a circle around its burrow entrance. It was examined whether the spider selects and places stones according to physical characteristics. Circle composition can be explained by the allometric scaling to spider size of the burrow entrance and the stones. The stones were usually placed with the narrowest side or point towards the burrow. Quartz crystals were preferred to four other stone types available. The spiders could detect prey brushing the outside of the circle stones that were about as wide as the spider's path of attack. I conclude that corolla spiders use the selected stones as tools to extend their foraging range.
Sperm Competition and Mate Guarding in Meadow Voles (Microtus pennsylvanicus)
Authors: Storey Anne E. , French Roberta J. , Payne Ronald
Published: May 2010

The relationship between sperm competition and behavioural forms of male competition was investigated by comparing paternity of litters when female meadow voles, Microtus pennsylvanicus, were exposed to two males sequentially (sperm competition only) or simultaneously (potential interaction between sperm competition and mate guarding). Voles were descended from two populations: one with naturally occurring blond voles (homozygous recessive) and the other with voles homozygous for the dominant dark coat. In sequential tests, blond females received one ejaculation each from one blond and one dark male (order of males varied among females). There were no mating‐order effects, but dark males sired more pups. Because this differential fertilization may have masked mating‐order effects, we repeated the experiment with voles homozygous for different transferrin genetic variants. Again, there were no significant mating‐order effects. When females were exposed to both males simultaneously, the aggressive blond males sired more pups because they mated more and effectively guarded females, thus preventing devaluation of their sperm by other matings. The more fertile dark males only sired pups if they mated first, before the blond males encountered the pair (a potential problem in field data on sperm precedence if more fertile individuals consistently mate either first or last). Mate guarding should reduce sperm competition from other males in high‐density populations. In contrast, finding and fertilizing females may be more important in low‐density populations, conclusions consistent with these population densities for several years prior to capture.
Why Be a Both‐ways Sex Changer?
Authors: Nakashima Yasuhiro , Kuwamura Tetsuo , Yogo Yutaka
Published: May 2010

Sex change is a rather common phenomenon among aquatic animals, but only a few have been reported to change sex in both directions. In laboratory experiments we demonstrated that the coral goby, Paragobiodon echinocephalus, changed sex in both directions with the same likelihood. When the goby lost its mate in the field, it preferred changing sex in either direction over moving a long distance in search of a heterosexual mate. Change in social rank, which is likely to occur in many other hermaphroditic fish, corresponded exactly with the direction of sex change. This constitutes a new condition for the evolution of both‐ways sex change among plants and animals.
Ontogenetic Behaviour Changes in Larvae of the DamselflyIschnura verticalis(Odonata: Coenagrionidae)
Authors: Richardson Jean M. L. , Anholt Bradley R.
Published: May 2010

Larvae of most animals go through large changes in size. Because change in size can lead to changes in ability to gain food and in predation risk, changes in behaviour are predicted to reflect this. Models consider change in amounts of the same behaviour, but different selective pressures on different larval sizes may also lead to qualitative differences in behavioural repertoire. In the damselflyIschnura verticaliswe observed ontogenetic changes in behaviour under controlled laboratory conditions. We found that frequency and duration of feeding behaviour and behaviour related to activity were increased in larger instars. Larger larvae also had higher transition probabilities to the behaviour abdomen wave, straight abdomen raise, and rotate + head out. We also found that the behavioural repertoire of damselfly larvae changed with development: some behavioural patterns were performed almost exclusively by smaller larvae (F ‐ 4 to F ‐ 7) while others were performed almost exclusively by larger larvae (F ‐ 3 to F ‐ 0).
Target‐directed Orientation in Displaced Honeybees
Authors: Geiger Karl , Kratzsch Daniela , Menzel Randolf
Published: May 2010

Under sunny weather conditions, displaced honeybees (Apis mellifera) usually fly into the celestial compass direction and thus may be misled from their goal, or they are disorientated. Under cloudy conditions, they may determine the celestial compass direction from prominent landmarks. They may also fly directly toward their goal from a release site. In two experiments, we investigated the orientation of displaced bees when a landmark (target) was close to the goal under different weather conditions. It is shown that in sunny conditions, the celestial compass will override target orientation under most conditions. Under 100% cloud cover, the celestial compass direction retrieved from landmarks modulates target‐orientated behaviour but is not by itself a primary orientation factor. The bees will fly toward a previously encountered landmark that signals the target, and in case of several similar landmarks which are visible to the bees, they will choose the one in the direction nearest the celestial compass direction. The results indicate that honeybee orientation is the result of a set of context‐specific interdependent orientation mechanisms.
Testosterone‐induced Singing in Female European Starlings (Sturnus vulgaris)
Authors: Hausberger M. , Henry L. , Richard M. A.
Published: May 2010

Adult female starlings (Sturnus vulgaris) were injected with testosterone in order to determine the song structures they had in memory. Those females had been caught in the wild in different geographical areas and had different ages. This hormone treatment clearly stimulated singing behaviour of females in isolation and revealed their ability to sing quite complex songs. Both categories of songs observed in males (warbling and whistles) were demonstrated and large repertoires were observed. Although the testosterone treatment may have altered the female song system and induced male‐like vocalizations, it is interesting that none of the species‐typic elements of male starlings was produced by the experimental females. Large changes were found in both repertoire size and composition over a year, revealing a high plasticity, even in older birds. We also found evidence that even under testosterone treatment, females do not necessarily sing all the songs they may have in memory.
Acquired Recognition of Chemical Stimuli from Pike, Esox lucius, by Brook Sticklebacks, Culaea inconstans (Osteichthyes, Gasterosteidae)
Authors: Chivers Douglas P. , Brown Grant E. , Smith R. Jan F.
Published: May 2010

In this study we test whether brook sticklebacks (Culaea inconstans) can acquire predator recognition through releaser‐induced recognition learning, i.e. simultaneous exposure to aversive ('releasing') stimuli and neutral stimuli causing learned aversion to the neutral stimuli. We exposed wild‐caught pike‐naive brook sticklebacks (collected from a creek containing fathead minnows, Pimephales promelas, but not pike, Esox lucius) to chemical stimuli from pike that were mixed with brook stickleback skin extract, fathead minnow skin extract, or a control of distilled water. In subsequent tests 2 d later, when only pike stimuli were presented, sticklebacks conditioned with stickleback skin extract and fathead minnow skin extract exhibited antipredator behaviour (i.e. increased schooling and movement toward the substrate), while those conditioned with distilled water did not. Sticklebacks conditioned with stickleback skin extract responded to pike with a more intense response, in terms of movement toward the substrate, than those conditioned with fathead minnow skin extract, suggesting that conspecific skin extract may be a stronger stimulus than heterospecific skin extract for learning recognition of predators. To our knowledge this is the first study to demonstrate that an acanthopterygian fish can acquire predator recognition through the pairing of conspecific alarm pheromone with the cue of a predator. Furthermore, our results are the first to demonstrate that fish can acquire predator recognition through the pairing of a heterospecific alarm pheromone with the cue of a predator. These results suggest that brook sticklebacks will benefit by being in close proximity to fathead minnows. Acquired predator recognition has long‐term consequences in mediating predator‐prey interactions.
Predation Risk Influences Reproductive Behaviour of Iowa Darters, Etheostoma exile (Osteichthyes, Percidae)
Authors: Chivers Douglas P. , Wisenden Brian D. , Smith R. Jan F.
Published: May 2010

In this study we tested the effects of predation risk on reproductive behaviour of Iowa darters (Etheostoma exile). We recorded the frequency of courtship behaviour (head shaking) and spawning acts for 30 min before and after removing an opaque barrier to expose groups of darters to (1) an empty tank (the before‐pike treatment), then (2) a tank containing a pike (the pike treatment), and finally (3) an empty tank (the after‐pike treatment). In response to the pike, darters performed significantly less reproductive behaviour than before exposure to the pike. Furthermore, darters performed proportionally less reproductive behaviour in the area in the immediate vicinity of the pike where risk of predation was highest. However, darters continued to occupy the risky area while exposed to the pike. Removal of the barrier in the absence of the pike (the before‐ and after‐pike treatments) had no effect on the overall level of reproductive behaviour, the proportion of reproductive behaviour performed in the immediate vicinity of the pike tank (the risky area), or use of the risky area.
Chemical Recognition of Risky Habitats is Culturally Transmitted among Fathead Minnows, Pimephales promelas (Osteichthyes, Cyprinidae)
Authors: Chivers Douglas P. , Smith R. Jan F.
Published: May 2010

Fathead minnows (Pimephales promelas) have an alarm substance (AS), or 'Schreckstoff', in epidermal club cells. Mechanical damage to the skin, as caused by a predator attack, releases the AS. The area in which conspecifics detect AS may be considered dangerous or risky because of the high probability of a subsequent predator attack. We exposed fathead minnows to water from one of two habitats (an open‐water site and a vegetated‐cover site) that we mixed with either AS or a distilled water control. Upon subsequent exposure to water from these habitats alone, minnows showed an antipredator response to the water they experienced in conjunction with AS, but not to water they received in conjunction with the distilled water control. These results confirmed that minnows can be conditioned with AS to recognize chemical cues from high‐risk habitats. Naive minnows present during the fright response of conditioned minnows also exhibited antipredator behaviour, and subsequently responded when tested alone. Our results demonstrate that learned recognition of high‐risk habitats can be transmitted culturally, which may allow minnows to lower their risk of predation.
Natal Dispersal and Philopatry in the Carnivorous Marsupial Phascogale tapoatafa (Dasyuridae)
Authors: Soderquist Todd , Lill A.
Published: May 2010

The proximate and ultimate causes of dispersal in semelparous carnivorous marsupials (Phascogalinae) have previously been hypothesized to be maternal aggression and inbreeding avoidance, respectively. This study tests these hypotheses by exposing 26 litters of Phascogale tapoatafa to a diverse range of social and environmental conditions that potentially affect dispersal (e.g. supplemental feeding, post‐weaning desertion by the mother, orphaning, and release of subadults into unoccupied habitat). The mean dispersal age was 162 ± 5.6 d, which is about 3 wk after weaning is complete. Juvenile dispersal was strongly male biased under all conditions, suggesting that extrinsic proximate causes do not adequately account for male emigration. Home range establishment by males was contingent on the presence of females. Half of the monitored daughters were philopatric, and others typically settled adjacent to the natal site, thus possibly enhancing their reproductive potential by occupying an area of known resource quality. Because philopatry increases the risk of incest, females may be selected to preferentially mate with unrelated males (immigrants), when they are available, to avoid inbreeding. If so, the presence of immigrant males would reduce the probability of locally born, related males reproducing at their natal site. Thus inbreeding avoidance by females may create local mate competition among males and select for male dispersal. Emigration also ensured that males avoided inbreeding, but, if they dispersed into unoccupied habitat, male P. tapoatafa often returned to the natal area. This 'boomerang strategy' of returning to mate with related females suggests that, in the absence of conspecifics along the dispersal path of a male, mate competition will be weak at the natal site and female mate choice will not preclude related males. Thus while inbreeding avoidance by either or both sexes is perhaps the most parsimonious explanation of male‐biased emigration, dispersal patterns were apparently strongly influenced by additional factors, so that the ultimate causation of the dispersal regime may be more complex.
Nest Defence of Nesting Chinstrap Penguins (Pygoscelis antarctica) against Intruders
Authors: Viñuela Javier , Amat Juan A. , Ferrer Miguel
Published: May 2010

We tested some predictions of parental investment theory by studying the aggressive behaviour of colonial nesting chinstrap penguins (Pygoscelis antarctica) against human intruders into their nesting territories. We tested for differences in the aggressive behaviour of penguins according to offspring age (eggs vs. chicks), offspring number, nest location in the colonies (central vs. peripheral) and sex. Offspring age was the main factor influencing nest defence, although nest location and sex were also important. Chicks were defended more strongly than eggs, in accordance with changes in the reproductive value of offspring, and this increase in aggressiveness was not related to revisitation of the same individuals. The level of aggression of penguins breeding in central sites was higher than that of peripheral birds, a difference that could be due to the lower residual reproductive value of central‐nesting, probably older, birds. The stronger aggressiveness of males could be due to a combination of factors related to sexual selection and life‐history traits. Offspring number did not affect the level of nest defence.
Behavioural Flexibility in a Small African Antelope: Group Size and Composition in the Oribi (Ourebia ourebi, Bovidae)
Authors: Arcese Peter , Jongejan Gwen , Sinclair A. R. E.
Published: May 2010

Individually identifiedOurebia ourebi(Bovidae) were observed in Serengeti National Park for 1–8 mo, annually, from 1987 to 1993 to study flexibility in the size and composition of territorial groups. A total of 236O. ourebiwere resighted over periods of 1 yr or more. The modal number of adults in groups was three in all years (range: 1–7; x̄ = 3.1, SE = 0.2, n = 5 yr; 136 groups overall); maximum group size with adolescent young and calves was eight. In 32% of 136 identified groups, two adult males were resident for at least 1 yr, as were three adult males in 4% of all groups. Groups with up to three adult females were common (range: 0–5). Overall, 25% of 32 adult males and 27% of 26 adult females were still present on the territory where first identified after 4 yr. Only 14% of 35 male‐female dyads remained intact over the same period.O. ourebiin Serengeti appear to be primarily polygynous, with a moderate rate of yr‐to‐yr residency in particular groups, and with a low rate of long‐term pairing between males and females. Groups with more than one adult male are not unique to Serengeti but their significance has not been previously considered. Comparisons acrossO. ourebipopulations in Africa show that polygyny is positively correlated with the ratio of adult females to males, population density, mean group size, and the prevalence of multi‐male groups, but there is less evidence that these variables influence the number of adult males in groups. Experiments are required to determine how demography, predation pressure, and the quality and distribution of food influence group size and composition inO. ourebiand other small antelope.
Familiarity with Intruders Modulates Agonism towards Outgroup Conspecifics in Wied's Black‐tufted‐ear Marmoset (Callithrix kuhli: Primates, Callitrichidae)
Authors: French Jeffrey A. , Schaffner Colleen M. , Shepherd Rebecca E. , Miller Marnie E.
Published: May 2010

Encounters between individuals in established groups have important implications for demographic processes. While most intergroup encounters in callitrichid primates (marmosets and tamarins) are characterized by intense agonistic exchanges, some interactions occur in the absence of aggression. This paper investigates the role of familiarity among partners in determining the quality and intensity of aggression during stranger encounters in Wied's black‐tufted‐ear marmoset (Callithrix kuhli). Resident male and female pairs were presented on several occasions with a single male or female intruder. Half of the intruders were housed in cages in colony rooms distant from the residents, and the other half of the intruders resided in cages in the same room as the residents. Aggression was higher in male residents than in females, and males showed significantly higher rates of agonistic interactions with unfamiliar intruders of both sexes. The behaviour of the intruder did not differ according to its degree of familiarity to the residents, although aggression by resident males and submission by intruders were highly correlated in encounters with unfamiliar, but not familiar, intruders. Resident pairs approached each other more often after intruder trials than before. The results of this experiment suggest that familiarity among individuals in neighbouring groups is sufficient to modulate aggression during encounters. Since home‐range overlap among free‐ranging black‐tuftedear marmosets is extensive, differential familiarity among groups may have important implications for dispersal‐related processes.
Do Great Tits (Parus major) Prefer Ectoparasite‐free Roost Sites? An Experiment
Authors: Merilä Juha , Allander Klas
Published: May 2010

To investigate whether great tits (Parus major) avoid roosting in flea‐(Ceratophyllus sp.) infested nest boxes, roost‐site selection in relation to naturally occurring flea numbers was studied in two nest box areas on Gotland, Sweden. In one area (A), every second nest box was provided with an old tit nest, while the rest were cleaned and left empty. In the other area (B), a choice was offered between empty boxes and boxes containing old collared‐flycatcher (Ficedula albicollis) nests. Great tits clearly preferred to roost in empty boxes in area A, but not in area B. However, there was no statistical evidence for differential preference in the two areas — a result consistent with the finding that there was no difference in flea numbers between old tit (area A) and flycatcher nests (area B). The interpretation that roost‐site choice was affected by parasite load was further supported by the fact that individuals roosting in boxes with an old nest preferentially chose boxes with low flea numbers.
Active Acoustic Gleaning from the Water Surface by the Indian False Vampire Bat, Megaderma lyra
Authors: Marimuthu G. , Habersetzer Jörg , Leippert Dieter
Published: May 2010

1 The method employed by the Indian false vampire bat Megaderma lyra (body mass about 40 g) to detect and capture prey from the surface of an artificial pond in an outdoor enclosure was studied. Frogs (Rana tigerina) (body mass about 10 g) were used as prey. The bats exhibited searching flights at the surface of the water for a few minutes in darkness, detected a stationary frog with its head jutting out of the water, and with a dart captured the frog in the mouth after hovering over it for about 2 s. The detected frogs did not show any movement when the bats hovered over them.

2 When a freshly killed frog alone was available and pinned with its head protruding out of the surface of the water, the bats captured it after making fewer numbers of attempts in a shorter period of time compared with the capture of live frogs. The number of attempts and time taken to capture a frog increased when the frog's eyeballs alone were exposed above the water surface, and the bats failed to detect frogs when their entire head was submerged just below the water.

3 Sound and video recordings showed that M. lyra continuously emitted faint ultrasounds while making searching flights at the pond. Apparently the bats made ‘early’ and ‘late’ detections, with higher repetition rates of sound emission in the case of the latter. A final buzz before capturing prey was not recorded and the change in the duration of emitted sounds during approach and after capturing the frog was marginal. The second harmonic at 43.6 kHz (SD 3.5 kHz) was more dominant and the duration was 1.0 ms (SD 0.2 ms).

4 It is clear that M. lyra uses echolocation to detect and capture prey from the water surface. A comparison is made with an earlier report on M. lyra catching prey from the ground by a passive acoustic location.
Structure and Organization of Local Migrations in Brown Surgeonfish (Acanthurus nigrofuscus)
Authors: Mazeroll Anthony Inder , Montgomery W. Linn
Published: May 2010

In the northern Red Sea (Gulf of Aqaba, Israel), brown surgeonfish (Acanthuridae: Acanthurus nigrofuscus) migrate, in small groups, up to 1.5 km each day from nocturnal shelters to feeding sites in the morning, and from feeding sites back to shelters in the late afternoon. During the summer spawning season, groups of these fish undertake an additional migration of up to 1 km to and from sites of mass‐spawning aggregations. The total number of fish migrating to the Laromme feeding site was relatively stable (X̄ = 1018) throughout the study period (1988–1990). By contrast, the number of fish arriving at the Lighthouse spawning site fluctuated drastically (˜50‐ > 2000), with the largest number of fish recorded around the new moon and the lowest within 1–2 days of a full moon. Durations of the migrations to and from the feeding site were similar, as were the numbers of groups arriving and departing the feeding site. In contrast, the duration of migration and number of groups were much greater during arrivals at the spawning site than during departure, due to an explosive emigration from the site following mass spawning. Arrival and departure routes differed at both feeding and spawning sites, demonstrating that simple route‐reversal is not practiced by these fish. Exchanges of position by leading and following fish in groups were rare, suggesting that leadership may play important roles in determining specific routes. Surgeonfish returning from spawning in early evening ceased migrating at a specific time, rather than a specific place, and completed their homeward‐bound migrations the next morning.
Rabbit‐mothers' Diet Influences Pups' Later Food Choice
Authors: Altbäcker V. , Hudson R. , Bilkó Á.
Published: May 2010

Choosing an appropriate diet raises special problems for generalist herbivores, especially in areas where most of the plant species are poisonous. This was the case in our study site, the Bugac Juniper Forest (Kiskunsag National Park, Hungary). The main herbivore of this forest, the wild rabbit (Oryctolagus cuniculus), can choose from about 70 plant species, but several of these are toxic or only of medicinal value. Moreover, even the nutritious species of the sparse vegetation are available only for short periods. The annual mortality rate is extremely high for the young, only those individuals survive that can find suitable places to hide and the least poisonous plants to eat. This selection pressure might force the pups to get information about the edible food types as early as possible, i.e. in the nest from their mother.

This hypothesis was experimentally tested using domestic, chinchilla‐breed rabbits. Three groups of females were kept on three different diets during the gestation and lactation periods. Just after weaning, food choices of differently treated mothers' pups were tested in a three‐way food‐choice test lasting 1 wk. The first choices were registered and the amount of food eaten from the different food items was measured during each test session. Analysis of the results of the first choices revealed that the animals started to eat the same food their mother had eaten during pregnancy and lactation. Analysis of the consumed amounts also supported this finding. Pups of treated mothers significantly preferred the aromatic plants their mother had eaten previously, even if it caused serious disadvantages to the young by reducing the number of offspring and increasing the mortality rate of the pups. The results of these experiments suggest that food preferences in wild rabbits can be transmitted from one generation to the other by social learning, although, to keep a balanced diet in an ever changing environment, individual experience and learning are indispensable.
Vigilance, Flock Size, and Flock Geometry: Information Gathering by Western Evening Grosbeaks (Aves, Fringillidae)
Authors: Bekoff Marc
Published: May 2010

Vigilance (scanning) and other behaviour patterns were studied in free‐ranging evening grosbeaks (Coccothraustes vespertinus) at feeders to assess how flock size and flock geometry influenced the behaviour of individual birds. The present results indicate that the way in which individual grosbeaks are positioned with respect to one another affects many aspects of their behaviour, especially when a flock contains four or more birds. Birds in a linear array which have difficulty seeing one another, when compared with individuals organized in a circle which can easily see one another: 1. are more vigilant; 2. change their head and body positions more often; 3. react to changes in group size more slowly; 4. show less coordination in head movements; and 5. show more variability in all measures. These differences in behaviour can be explained from a cognitive ethological perspective that favours intentional or representational explanations. Specifically, the data suggest that individual grosbeaks, when scanning and moving about, are visually monitoring the flock in which they are feeding and gathering information about a number of variables including flock size, what others are doing, where others are, which individuals are present, phenotypic features of flock members, food resources, or the location of potential predators. Individuals likely use visual records of the behaviour and perhaps the phenotypic features of others, and this information influences various aspects of their behaviour.
Intruder Pressure Affects Territory Size and Foraging Success in Asymmetric Contests in the Water Strider Gerris lacustris
Authors: Jabłoński Piotr G.
Published: May 2010

The theory of evolutionarily stable strategies (ESS) in asymmetric contests predicts that the propensity of an individual to expose itself to risk during contests depends on the individual's resource‐holding‐potential (RHP) and on the value of the disputed resource (V) for the individual compared with that for an opponent. If encounters of a territory owner with individuals of high RHP and high food demands (V) increase in frequency, one should expect a decrease in total aggressiveness of the territory owner, and in consequence a decrease of its territory size. Such a decrease should result in a lower amount of food consumed by the territory owner. Using natural variability in RHP and V in Gerris lacustris, I experimentally tested these predictions. The average prey item has higher value (V) for reproductive female water striders (which probably transform most of their food into eggs), than for nonreproductive females and for males. Because males are smaller, they have lower RHP than females, as RHP depends on size. Thus the reproductive females are the class of individuals of high RHP and high food demands (high V). Most nonreproductive females defend food‐based territories. I observed two groups of water striders in a seminatural laboratory setting. As predicted, there was a negative correlation between the rate of encounter with reproductive females and size of the territory, and a positive correlation between territory size and number of Drosophila flies consumed by the owner. Territories were smaller in the group with high rates of encounter between territory owners and reproductive females. Territory owners caught the same number of Drosophila flies as non‐territorial individuals in this group. In contrast, in the group with fewer encounters between territory owners and reproductive females, territories were larger, and territory owners gained more food than non territorial water striders.
Song Repertoire of the Bobolink: a Reassessment
Authors: Trainer Jill M. , Plltz Brenda S.
Published: May 2010

Previous studies have reported that male bobolinks, Dolichonyx oryzivorus, sing only two stereotyped song types. Here we reassess this description of the bobolink repertoire, using methods of sampling and classifying songs better suited to describing song diversity. Recording the songs of 51 males from five prairies in Iowa, we examined within‐ and between‐individual variation for each of three levels of bobolink singing organization: phrases, phrase sequences and repertoires. A single song was composed of 1–15 phrases selected from about 10 locally used phrase types. Shared phrases were used with similar frequencies among different males at a locality. Two‐, three‐ and four‐phrase sequences were used repeatedly in the song variants produced by individual males. Unlike other investigators, we considered each song unit composed of a unique sequence of phrases to be a different song variant. Some individuals had two basic song patterns which were varied to create an assortment of song variants. Other individuals had repertoires too complex to be described by two basic patterns. Eighteen males for which we obtained samples of 20 or more songs sang between 8 and 43 different song variants. Computing an index of singing versatility derived from information theory, we found that these individuals varied considerably in the versatility with which they delivered their song variants. Males with high versatility used a greater variety of phrase transitions and repeated song variants less often than males with low versatility. This method of describing song repertoires and singing versatility provides the potential to test hypotheses regarding the role of the bobolink song repertoire in communication and mate choice.
Cere Colour as a Basis for Extra‐pair Preferences of Paired Male Budgerigars (Melopsittacus undulatus: Psittacidae: Aves)
Authors: Baltz Aliza P. , Clark Anne B.
Published: May 2010

Male budgerigars may be limited in the time they have available to pursue extra‐pair copulations because of conflicts with other reproductive behaviour. If males could selectively court only immediately fertilizable extra‐pair females they should do so. The cere colour of a female budgerigar may be used as a cue to her reproductive readiness. We experimentally tested the hypothesis that males prefer females with dark ceres, which are indicative of developed ovaries, over females with light‐coloured ceres, characteristic of birds with undeveloped ovaries. In a pairwise choice experiment between females that had their cere colour artificially manipulated, pair‐bonded males were more likely to choose the female with the dark‐coloured cere.
Lack of Mate‐guarding in a Territorial Passerine Bird with a Low Intensity of Sperm Competition, the Pied Flycatcher; (Ficedula hypoleuca)
Authors: Chek Andrew A. , Lifjeed Jan T. , Robertson Raleigh J.
Published: May 2010

We examined a Norwegian population of pied flycatchers (Ficedula hypoleuca) for behaviour associated with the paternity‐protection tactic of mate‐guarding and found that this tactic was absent. The absence of mate‐guarding and the fact that pied flycatchers do not have a high rate of copulation make this population unusual to the extent that the current literature implies that, in birds, one or other paternity guard should be present. Comparison of our population with a Swedish population that does exhibit mate‐guarding lends some support to the notion that differences in nesting density may drive the relative risk of extra‐pair copulation, leading to the need for paternity guards such as mate‐guarding. However, we conclude that, whilst the results of both our study and the Swedish study are consistent with the nesting‐density hypothesis, there is at least one other plausible hypothesis that fits the available data. Specifically, we direct attention to the role of the female in determining overall patterns of pair behaviour and, potentially, the rate of extra‐pair paternity, challenging the primacy of male—male competition as the driving force behind the sperm‐competition dynamics of this species.
Social Learning of a Novel Foraging Skill by White‐throated Magpie‐jays (Calocitta formosa, Corvidae): a Field Experiment
Authors: Langen Tom A.
Published: May 2010

The cooperatively breeding white‐throated magpie‐jay (Calocitta formosa) uses a variety of foraging tactics to find, harvest, and process food. Members of territorial groups forage together and may gain information about how to acquire food by observing each other. A field experiment was performed to determine whether a novel skill, door opening to gain access to food, was more rapidly acquired by members of groups in which a trained individual performed the skill. A higher proportion of jays in groups with behavioural ‘models’ (trained birds that opened doors in the presence of group members) acquired the door‐opening skill than those groups without models. Young birds acquired the behaviour more frequently than older individuals. Aggressive behaviour at feeders may have affected the spread of the behaviour by reducing the likelihood that individuals performed the behaviour in the presence of other group members but may also have encouraged subordinate individuals to attempt door opening rather than ‘scrounge’.