bluuebunny/crossref_metadata_2025_split huggingface dataset:
Male Choice and Male‐male Competition in Idotea baitica (Crustacea, Isopoda)
Authors: Jormalainen Veijo , Merilaita Sami , Tuomi Juha 
Published: May 2010

AbstractSexual selection in mate‐guarding Crustacea may involve several processes: male choice, male‐male competition, and female choice. To evaluate the relative importance of the different processes in mate choice of the aquatic isopod I. baitica we studied 1) the mate‐choice criteria of males, 2) effects of sex ratio on the outcome of the mating contest, and 3) the role of size in male‐male interactions. When given a choice between a small and a large female, males most often chose the one that matured earlier for parturial ecdysis. Maturity was a more important choice criterion than female size, but these also correlated positively. Large males had a mating advantage in both male‐ and female‐biased sex ratios; pairing was size‐assortative only in the male‐biased ratio where guarding was also longer. If an extra male was placed with a precopulatory pair, 30 % take‐overs occurred, large males surpassing. Present and earlier work suggests that male size is an asset in both intra‐ and intersexual interactions. There is little or no direct phenotypic sexual selection on female size: sexual selection for large males presumably contributes to the evolution of sexual size dimorphism in I. baitica.
The Utility of the Proximate‐Ultimate Dichotomy in Ethology
Authors: Alcock John , Sherman Paul 
Published: May 2010

AbstractWe defend the organizing principle that there are fundamentally different levels of analysis in biology, notably proximate and ultimate. Despite recent claims to the contrary, the proximate‐ultimate distinction is a true dichotomy, not an artificial division of a continuum. Acceptance of this dichotomy does not imply that ultimate questions are of greater importance than those dealing with proximate mechanisms, nor does it result in confusion of current reproductive consequences with evolutionary causes.
On the Utility of the Proximate‐Ultimate Distinction in the Study of Animal Behavior
Authors: Dewsbury Donald A. 
Published: May 2010

AbstractThe importance of Tinbergen's “four problems” approach lies in assuring that the answers provided are truly appropriate to the questions that are asked. No problem is any more important than any other. I suggest that the spirit of this formulation can be best realized if we revise the ways in which recent authors have grouped the various problems in the study of behavior. One consequence of this regrouping is an elimination of the proximate‐ultimate dichotomy.
The Influence of Food Competition and Prédation Risk on Size‐assortative Shoaling in Juvenile Chub (Leuciscus cephalus)
Authors: Krause Jens 
Published: May 2010

AbstractSize‐assortative shoaling is a widespread phenomenon potentially linked to competition for resources among shoal members and anti‐predator benefits gained from living in shoals. This paper investigates the influence of both factors on size‐assortative shoaling in chub (Leuciscus cephalus). In a first experiment food competition was studied by manipulating the proportions of small and large chub in shoals of 20 fish. Large fish were generally more competitive than small ones. However, the competitive effect of large fish was strongly dependent on their number in the shoal. This has important consequences for the theory of competition because it makes it difficult to predict stable combinations of different phenotypes when foragers divide between food patches. Despite the strong effects of food competition no significant trend for size‐assortativeness was observed in free‐swimming shoals when undisturbed. This changed after the shoal had been frightened by introducing Schreckstoff (an alarm substance) to the test tank. Large and small fish still remained in the same shoal but showed a strong preference to be close to neighbours of their own size class. Large fish were observed mainly in the centre of the shoal and small fish were found more in the periphery. It is unclear whether these position differences are due to aggressive behaviour of large fish towards small fish which excludes them from the potentially safe centre of the shoal. These results indicate that prédation plays a more important role than food competition for size‐assortative shoaling in chub.
Male Incubation and its Effect on Reproductive Success in the Black Swan, Cygnus atratus
Authors: Brugger C. , Taborsky M. 
Published: May 2010

AbstractMale incubation is very unusual among Anatidae. In the black swan, males spend more time incubating the clutch than females do. We investigated the incubation patterns of males and females in a breeding colony in Vienna over a one‐year period. Breeding occurred year round, with a peak in winter. Inattentive periods during incubation were shorter in winter than at other times of the year, probably because the heat loss of eggs is then higher. We tested the importance of the costs of incubation by prolonging the breeding period experimentally. Eggs were exchanged for dummies, which were readily accepted and incubated for up to 342 days. The higher the incubation effort of females, measured as the product of their proportion of incubation and the total length of the incubation phase, the longer was the interval between the end of incubation and laying of a subsequent clutch. This suggests that the incubation effort of females is limiting the reproductive output of a pair. By taking charge of the greater part of incubation, males may increase the productivity of their female partners and thereby their own reproductive success. This amplification of female fecundity is a factor favouring a high share in male incubation which is discussed in polyandrous species (e.g. Jenni 1974) but generally overlooked in monogamous systems. The ultimate cause for male incubation in black swans may lie in the combination of a monogamous mating system and the capability of this species to breed whenever the environmental conditions turn favourable, at any time of the year.
Agonistic Interactions and the Distribution of Foraging Organisms: Individual Costs and Social Information
Authors: Kennedy Martyn , Gray Russell D. 
Published: May 2010

AbstractThe results of a previous experiment we conducted suggested that agonistic interactions may, counterintuitively, attract organisms to food sites rather than drive them away. In this study we test whether interactions attract or deter organisms by manipulating the distribution of interactions in a natural population of mallard ducks (Anas platyrhynchos L.). We manipulated the distribution of interactions by changing the size of the bread fed to the ducks from two food sites. In the condition with large pieces of bread the distribution of interactions between the two food sites was more extreme than in the small bread condition. The attraction hypothesis predicted that the distribution of ducks should be more extreme in this condition, whereas the deterrence hypothesis predicted that the distribution of ducks should be less extreme. We found that the distribution of ducks was significantly more extreme in the large bread condition. This supports the hypothesis that agonistic interactions act as a net attraction to foraging organisms. The possible benefits organisms may gain from agonistic interactions are discussed.
Social Factors Influence the Acoustic Variability in the Long‐distance Calls of Male Chimpanzees
Authors: Mitani John C. , Brandt Kari L. 
Published: May 2010

AbstractAcoustic variability in the species‐typical long‐distance calls of male chimpanzees was investigated. Analysis of 13 acoustic features revealed that calls varied more within than between individuals. Although only a limited amount of acoustic variability was attributable to different populations, discriminant‐function analysis confirmed that males from two populations produce acoustically distinguishable calls. Additional investigation suggested that social factors may contribute to the patterns of acoustic variation both between and within individuals. Matrix‐permutation tests revealed a positive association between the amount of time males spent together and a measure of call similarity. Vocal similarities between individuals appeared to result from a dynamic process involving chorusing behaviour: males matched the acoustic characteristics of each other's vocalizations when calling together. Chorusing may also affect the degree of within‐individual acoustic variation in calls. Males who chorused often with others produced more variable calls than individuals who chorused less often or called alone.
Female Response to Reduced Male Parental Care in Birds: An Experiment in Tree Swallows
Authors: Whittingham Linda A. , Dunn Peter O. , Robertson Raleigh J. 
Published: May 2010

AbstractIn biparental species, parental‐investment theory generally predicts an inverse relationship between the level of parental care provided by each parent and incomplete compensation by one parent in response to reduced parental care by their partner. The factors that influence the magnitude of this compensation have rarely been examined in birds. For example, the level of compensation may differ between a widowed bird that receives no assistance from its partner and a mated bird whose partner is still present but providing less than its normal share of parental care. This study compares the compensatory response of female tree swallows (Tachycineta bicolor) without their mate's parental assistance (when females are widowed) and with reduced male parental care (when males are handicapped by cutting some feathers). When compared with control females, experimental females compensated more in terms of nest visits for the absence than the reduction of male parental care. In addition, widowed females had significantly reduced brood mass and fledging success compared with control females. Although handicapped males reduced their nest‐visit rate significantly, females with handicapped mates did not significantly increase their nest‐visit rate nor was there reduced brood mass or reduced fledging success at their nests. Total nest‐visit rate was similar for all groups, yet widowed females fledged fewer and lighter young, suggesting that they brought less food per nest visit. We suggest that fledging success and measures of offspring quality are probably better indicators of the level of compensatory parental care than nest‐visit rate. We suggest that for widowed females the benefits of a relatively large compensatory response outweighed the costs; whereas, for females with a handicapped mate the benefits of higher feeding rates were not greater than the cost. The results of this study help to explain the differences among experimental studies of compensatory parental care and point to a new method of testing models of parental care.
Earthen Structures Built by Ilyoplax dentimerosa (Crustacea, Brachyura, Ocypodidae)
Authors: Wada Keiji 
Published: May 2010

AbstractUnder observation, the small ocypodid crab Ilyoplax dentimerosa was found to commonly build three types of earthen structures: a barricade near its neighbour's burrow, a fence at an intermediate position between the burrows of the builder and its neighbour, and a minishelter near the builder's burrow. The sex ratio of barricade builders was found to be close to 1:1, whereas most of the fence builders were found to be female. Crabs against which barricades and fences were built, were usually smaller than the builders. Both barricade builders and fence builders had, in most cases, minishelters at the side, facing the barricade or the fence. Removal and rebuilding experiments for barricades and fences demonstrated that both structures functioned to deter the approach of the builder's neighbour to the builder's activity site. Fences also had the effect of restraining the movement of the builder toward the fence site.
Eco‐ethological Factors Affecting the Scouting and Raiding Behaviour of the Slave‐making Ant, Polyergus rufescens Latr. (Hymenoptera, Formicidae)
Authors: le Moli Francesco , Grasso Donato Antonio , Mori Alessandra , Ugolini Alberto 
Published: May 2010

AbstractA dulotic colony of the obligatory slave‐making ant Polyergus rufescens was monitored daily in the field (Parma, Italy) from 1100–2000 h over the summers of 1991 and 1992. The first P. rufescens workers to emerge from the nest each day were individually marked and their activity was accurately recorded. The path of 47 such individuals (21 over a complete trip) was followed in detail and mapped. Results confirm a clear scouting activity: the route of these workers away from the nest is generally tortuous and time consuming and is followed by a return trip along a different and straighter path. Observations also showed that these scouts recruit nestmates and lead raiding columns towards target nests, confirming their important role in the organization of slave raids. The similarity between routes taken by scouts and raiders during outbound trips indicates the close connection between scouting and raiding activity, which was also recorded in detail since 40 raids were observed. Some experiments analysing the orientation behaviour of inbound columns showed that raiders use a chemical trail (deposited during the outbound run) to lead them back home. The hypothesis of a multiple strategy for the location of host colonies operated by this slave‐making species is also discussed.
Nocturnal Activity of Caged Resident and Migrant Silvereyes (Zosteropidae: Aves)
Authors: Chan Ken 
Published: May 2010

AbstractNight‐activity patterns of individually‐caged grey‐breasted silvereyes Zosterops lateralis of resident and migrant status were investigated. True migratory restlessness or ‘Zugunruhe’ was exhibited by some individuals, but there was also considerable ‘noise’ in the data caused by cageing and neighbouring disturbance. In general, ‘Zugunruhe’ took place from about 2 h before, to about 4 h after ‘sunrise’, and both the daily timing and annual duration of Zugunruhe were consistent with the migration pattern observed in the field. A total of 42 % of resident birds from Tasmania, 77 % of migrant birds from Tasmania and 90 % of migrant birds from the mainland were considered to have exhibited true ‘Zugunruhe’, while none of the resident birds from Brisbane were considered to have displayed it. A few individuals spontaneously developed ‘Zugunruhe’ in the absence of other birds, but many birds (both residents and migrants) displayed no elevated night unrest when placed in a room on their own, although displaying unrest when placed among birds exhibiting ‘Zugunruhe’. The migration of the silvereye probably has a genetic basis, but whether an individual migrates or not is also influenced by social factors which differ in magnitude between individuals.
The Adaptive Significance of Avian Mobbing V. An Experimental Test of the ‘Move On’ Hypothesis
Authors: Flasskamp A. 
Published: May 2010

AbstractThis paper presents the first experimental study of the effects of mobbing on predators. Two captive little owls Athene noctua and a tawny owl Strix aluco, having stabilized activity patterns and roosting sites, were singly confronted with one or two mobbing blackbirds Turdus merula. The little owls showed marked stress (gular fluttering, panting and panic flights), abandoned chosen roosts and remained unsettled for several days. A permanent alternative roost was chosen after one mobbing encounter, other encounters resulted in several days of ‘floating’ before returning to the original sites. One little owl used ‘camouflage’ by ‘freezing’ during repeated harassments, the other tended to retaliate if mobbing was close and weak. The tawny owl seemed to ignore the rather weak blackbird mobbing, but abandoned its roost for up to 36 h when mobbed by larger numbers of woodland birds at close range. It is concluded that mobbing causes profound distress, especially in small, vulnerable predators like the little owl and forces it to change its daytime roost. If abandoning the area is not possible, time and energy are expended in increased vigilance as a protection against further mobbing attacks. Thus there is strong support for the ‘Move on’ hypothesis.Results also support the ‘Perception advertisement’ hypothesis, implying that the detected hunter deliberately forfeits the surprise element. Which effect prevails depends on predator evaluation of the signals involved.
Resource Management in the Orb‐Weaving Spider Zygiella x‐notata: I. Influence of Spider Behaviour and Available Prey
Authors: Sebrier Marie‐Anne , Pasquet Alain , Leborgne Raymond 
Published: May 2010

AbstractManagement of resource exploitation by the orb‐weaving spider Zygiella x‐notata was investigated in relation to available prey. Prey capture is studied according to prey type (cricket or fly), and the spider's behaviour (waiting without prey or consuming other prey), at the moment when a prey item was placed onto the web. Characteristics of the spider's exploitation of the previous item (feeding time, and quantities ingested) were analysed according to the type and quantity of prey presented, (1 or 2 items at 1‐h intervals). Capture time did not vary in relation to prey type, nor spider activity. However, duration and quantities of certain behavioural components (biting and wrapping) did vary according to prey type and the spider's behaviour, at the moment of presentation of prey. Whatever the type of prey received, if the first item consumed was a cricket, the spiders reduced time spent feeding on this prey without any decrease in the quantities ingested.
Resource Management in the Orb‐Weaving Spider Zygiella x‐notata II. Ability to Manage a Set of Various Prey
Authors: Sebrier Marie‐Anne , Pasquet Alain , Leborgne Raymond 
Published: May 2010

AbstractManagement of a set of various prey received ‘simultaneously’ by the orb‐weaving spider Zygiella x‐notata is investigated in relation to prey species, weight, order of arrival in the web, and factors concerning the spider's state of nourishment.When the spiders encountered several different prey ‘simultaneously’, they subdued all of them, took one of them to begin consumption, and stored the others in the web. The first item for consumption was chosen according to the characteristics of the available prey. Factors concerning previous feeding influenced the spiders's choice of the first item to be ingested.Exploitation of the first item, estimated by the quantity of food extracted and the time necessary for this extraction, depended on the type and the quantity of prey at the spider's disposal. When the spiders received several prey, they spent less time feeding on the first cricket compared with spiders receiving only one cricket, while no difference was found when the first prey item exploited was a fly.
Female‐biased Sex Ratios in the Neotropical TreehopperUmbonia ataliba(Homoptera: Membracidae)
Authors: Masters Karen L. , Masters Alan R. , Forsyth Adrian 
Published: May 2010

AbstractThe authors report and explain female‐biased sex ratios in the neotropical treehopperUmbonia atalibaHomoptera: Membracidae at Monteverde, Costa Rica.Umbonia atalibamothers semelparously oviposit egg masses into host‐plant branches, make feeding holes, and guard the eggs and the nymphs until the young moult to become adults. At adulthood, offspring sex ratios are female‐biased, with families having, on average, one male per 3.17 females (SD = 0.149, n = 48). The female bias does not appear to be explained by the hypothesis that males are more difficult to raise to independence: males are smaller than females, males have a shorter development time, males do not require disproportionately more feeding holes, and males do not experience higher mortality in families that are unprotected from parasites and predators, rather, females die more often in protected families. Thus females, not males, may be more difficult to raise to independence. The authors investigated whether increases in the size of males and females increased the fitness of either sex disproportionately, but found no relationship between size and fitness for either sex. We found evidence that local‐mate competition conditions and inbreeding occur. Mating occurs at the natal site and nearly all copulations take place between siblings (99.3 %, n = 153 copulations). Most females (mean proportion of females = 0.65, SD = 0.33, n = 7 families) copulate with their male siblings prior to dispersing; whether the unmated proportion copulates later is unknown. This paper suggests that the numerical bias reflects aninvestmentbias favoured under selection by inbreeding and local‐mate competition conditions.
The Role of Visual Familiarity with the Landscape in Pigeon Homing
Authors: Wallraff Hans G. , Kiepenheuer Jakob , Streng Andrea 
Published: May 2010

AbstractIn an introductory discussion it is argued why a topographical ‘pattern map’ based on a familiar visual landscape should come into conflict with an angular shift of the sun compass, whereas a ‘point map’ based on atmospheric odours is expected to be freely rotatable by compass shifts. To test whether these predictions are met, releases were conducted in a familiar area with pigeons whose circadian clock was shifted 6 h forward. Half of the pigeons were prevented from smelling natural airborne odours by air filtration before release and nasal anaesthesia upon release. Analysis of initial bearings, also including earlier releases in unfamiliar areas, led to the following results. (1) Unfamiliar area, olfaction unimpaired (only assumed point map applicable): full deflection of bearings according to the amount of sun‐compass shift. (2) Familiar area, olfaction unimpaired (both point map and pattern map applicable): average deflection of bearings somewhat smaller than compass shift. (3) Familiar area, no olfactory access to natural air (only assumed pattern map applicable): average deflection of bearings only about half compass shift; increased variability. Corresponding non‐shifted controls were always homeward orientated.Results support the hypothesis that pigeons in a familiar area, if relying exclusively on non‐olfactory spatial information, utilize the visible landscape to find the way home. Certainly they also do so under normal conditions when additionally available airborne odours co‐determine behaviour, so that the investigator is unable to separate the roles of vision and olfaction. This most plausible and parsimonious hypothesis should be falsified before consideration of alternative hypotheses suggesting there are some mysterious unknown factors at work. How pigeons may view and evaluate the landscape for orientation over longer distances is briefly discussed.
Acoustic Orientation and Communication in Desert Tenebrionid Beetles in Sand Dunes
Authors: Hanrahan Shirley A. , Kirchner Wolfgang H. 
Published: May 2010

AbstractAcoustic orientation and communication were studied in five species of tenebrionid beetles found in the Namib Desert in Namibia. The thresholds of their sense of vibration were studied in behavioural experiments. High sensitivity to substrate sound was found in those species restricted to living in sand dunes. Wind blowing over the surface of the sand was found to induce substrate noise perceivable to beetles buried in the sand. One species studied responded to this noise by coming to the surface. Detritus, a major food source, is freed from the sand by wind and concentrated at dune slipfaces. The noise generated by the wind is an important signal to the buried beetles that food is available. It is possible for beetles on the surface of the sand to perceive noises made by buried conspecifics and for buried beetles to perceive others walking on the sand surface.