bluuebunny/crossref_metadata_2025 huggingface dataset:
Social Effects of Maternal Age and Experience in Bison: Pre‐ and Post‐weaning Contact Maintenance with Daughters
Authors: Green Wendy C. H.
Published: May 2010

Effects of maternal age and experience on long‐term contact maintenance interactions with female offspring were examined in bison (Bison bison), as part of a study of factors influencing dyadic behavioural interaction. During the first five months, patterns of change in interactions varied with maternal age and parity. Young (largely primiparous) mothers and their calves steadily increased the frequency with which they maintained contact, while older mothers and their calves became increasingly independent (e.g. calves walked away from mothers more and followed them less often). Filial independence was most extreme in the (last) calves of the two oldest mothers. These age‐specific patterns appeared to result largely from contrasting shifts in maternal behaviour from Month 1 to 2; differences between groups before and after this shift were opposite in direction. In the first month, older mothers maintained more frequent contact and were behaviourally more synchronized with their calves. After the first month, however, the efforts of older mothers to maintain dyadic proximity abruptly decreased, while those of young mothers and their calves gradually increased. Subsequent differences between groups were more consistent. Young mothers and their daughters maintained closer contact and continued to do so well past weaning, at least as late as the third year, when daughters reached sexual maturity. Filial behaviour played an important role in determining patterns of dyadic spatial relations; the close proximity maintained by young mothers and their offspring appeared due largely to the frequency with which these calves followed their mothers' movements. The relatively independent calves of older mothers took greater initiative in contact interactions with mothers (e.g. nosing, licking). Young mothers appeared to strengthen long‐term bonds with daughters by initiating contact frequently; the closeness of post‐weaning dyadic association increased with the frequency of pre‐weaning maternal contact.
Variation in Song Rate during the Breeding Cycle of the Chaffinch, Fringilla coelebs
Authors: Hanski Ilpo K. , Laurila Anssi
Published: May 2010

The variation in song rate during the breeding season was studied in two individually marked chaffinch Fringilla coelebs populations. We gathered data to investigate especially the recently presented mate‐guarding hypothesis. The active singing has been supposed to function as a form of mate guarding during the female's fertile period by announcing the high status of the male and preventing extra‐pair copulations by neighbouring males.

There was no clear dawn chorus in the chaffinch, i.e. a peak in the song rate before sunrise. Male chaffinches continued to sing after mating, but the song rate dropped significantly. In contrast to the mate‐guarding hypothesis the song rate was lower during the fertile period of the female than during pre‐mating and incubation. Thus, the males do not announce the fertility status of their mates or their own quality and status by active singing. The song does not function as a form of mate guarding in the chaffinch.

One function of the song of the chaffinch is mate attraction: singing activity was highest before pair formation in early spring and decreased after mating but increased again if the male lost his mate later in the breeding season.
Songs of American Redstarts (Setophaga ruticilla): Sequencing Rules and their Relationships to Repertoire Size
Authors: Lemon Robert E. , Dobson Charles W. , Clifton Peter G.
Published: May 2010

In order to determine the rules of sequencing of songs used by American redstarts, we related Markovian and hierarchical models to recordings obtained from free‐living males. In the smaller repertoires of three or four songs, low order Markov chain models fitted the data. 9 of the 10 sequences so examined were first‐order, and the last was second‐order. Larger repertoires of 6 and 8 songs were hierarchical in organization with subsets of songs having independent sequencing rules. Most samples of singing were stationary in their transition rules over periods of several days: non‐stationarity was sometimes associated with a change in the number of songs forming the sequence, or in repetitions of songs. We examine causal models of song sequencing and conclude that our results generally favor competition models, although some sequential dependencies may also apply. Hierarchical organization in the serial repertoires of American redstarts may reflect developmental influences rather than effects of repertoire size itself.
Social Control over the Survival and Selection of Winged Virgin Queens in an Ant without Nuptial Flight: Iridomyrmex humilis
Authors: Passera Luc , Aron Serge
Published: May 2010

Laboratory and field experiments show that the number of winged virgin queens of the Argentine ant Iridomyrmex humilis allowed to remain alive in the nest is under social control. When reared in their natal nest, survival of virgin queens depends on the presence of males. In the presence of mature alate males or even male pupae only 20% of the gynes are executed before they are 4 days old. By contrast, if pupal and adult males are absent, about 55% of the gynes are executed. The workers tend to kill the lightest ones. Although the Argentine ant is a unicolonial species exhibiting complete acceptance of foreign conspecific workers and mated queens, regardless of whether the recipient nest is queenright or queenless, the acceptance of gynes is variable: they are executed by foreign queenless workers but widely accepted in queenright nests. These results are discussed with regard to possible existence of queen and gyne pheromones allowing recognition and to the lack of nuptial flight in this species.
A Comparative Study of Social Behaviour of Two Sympatric Ground Squirrels (Spermophilus spilosoma, S. mexicanus)
Authors: Livoreil B. , Gouat P. , Baudoin C.
Published: May 2010

During the reproductive period, intraspecific dyadic encounters were staged within and between S. spilosoma and S. mexicanus individuals under controlled conditions. Video recordings were used to describe and quantify behaviour of males and females of these two sympatric ground squirrels. To compare dyads within and between species two indices (an Agonistic index and a Tolerance index) were designed from measures of behavioural frequencies. During intrasexual encounters, S. mexicanns males and females appear to be more aggressive than male and female S. spilosoma. In both species, encounters between males were more aggressive than between females, which were very tolerant to each other in S. spilosoma. In most cases encounters between male and female conspecifics exhibit an intermediate level of agonistic behaviour and tolerance.

The null hypothesis of similarity of the social behaviour of S. spilosoma and S. mexicanus is falsified. Some alternative hypotheses are proposed. First, the tolerance of S. spilosoma is an adaptation to the difficult environmental conditions. Thus differences between the two species reflect differences in behavioural evolution in allopatric populations. Second, S. spilosoma tolerance is a behavioural response to S. mexicanus' recent arrival.
Variation in the Sonar of an Aerial‐hawking Bat (Eptesicus nilssonii)
Authors: Rydell Jens
Published: May 2010

Echolocation calls from 10 individually marked female northern bats (Eptesicus nilssonii) were recorded as the bats foraged at three distinct feeding sites (territories) near their maternity roost in southern Sweden (57° N). In addition, recordings of unmarked bats were made in northern Sweden (65° N). The frequency at maximum amplitude of “search phase” echolocation pulses was bimodally distributed, with peaks around 29–30 kHz and 31–32 kHz and was negatively correlated with pulse duration. The frequency at maximum amplitude was related to flight altitude (bats used higher frequencies when they flew near the ground) and also differed among the feeding sites. Hence, much of the variation, probably including regional differences, was behavioural and is interpreted as short term (in the order of s or min) adaptation to current foraging situations. Variation among individual bats, caused by age and size, seemed to be of less importance. Individuals did not use exclusive frequency bands.
Fission of a Spotted Hyena Clan: Consequences of Prolonged Female Absenteeism and Causes of Female Emigration
Authors: Holekamp K. E. , Ogutu J. O. , Dublin H. T. , Frank L. G. , Smale L.
Published: May 2010

We describe the fission of one large East African clan of spotted hyenas (Crocuta crocuta). During an 8‐mo period from late 1989 to early 1990, 8 of 22 adult females vanished from the clan, along with their juvenile offspring. 6 of these 8 adult females formed a new clan in an area adjacent to the parent clan's home range. The 6 adult female dispersers belonged to three mid‐ or low‐ranking matrilines in the parent clan. Two juvenile males returned to the parent clan for temporary visits, and three female members of one matriline rejoined the parent clan after absences of over 8 mo. Returning females, but not males, were targets of severe aggression by adult female residents of the parent clan, and by juvenile residents of both sexes. Returning females fell from their previous mid‐ranking positions to the bottom of the adult female hierarchy. Our data suggest that clan fission was promoted by the simultaneous occurrence of low food availability, an unusually high density of higher‐ranking conspecific competitors, and the availability of neighboring vacant habitat.
Behavioural Divergence in Allopatric and Sympatric Gerbil Species (Rodentia: Gerbillinae)
Authors: Dempster Edith R. , Dempster R. , Perrin M. R.
Published: May 2010

Southern African gerbils comprise 3 genera, each genus represented by morphologically‐ and ecologically‐similar species. All species are monomorphic, with social systems varying from asocial (Desmodillus auricularis) to colonial (Tatera species).

This study compares the behaviour patterns of an allopatric species, T. afra, 2 sympatric species, T. leucogaster and T. brantsii, and a species of a different genus, D. auricularis which is sympatric with T. leucogaster and T. brantsii.

Interactions between males and females of the same species were staged and quantified in terms of the frequencies of each of 23 behavioural acts. D. auricularis performed 2 acts, namely “sidle” and “fight” which have not been identified in Gerbillurus or Tatera interactions. Sequences of behaviour were similar in all species, and involved females moving away from males, which followed, sniffed the anogenital region and attempted to mount the females. Females responded by presenting, if receptive, or agonistic behaviour such as aggressive or upright postures. Exploration of the terrarium accounted for a large proportion of the behaviour during the 20 min encounter, and watching the opponent also occurred frequently.

Discriminant function analysis successfully separated all 4 species on the basis of behaviour frequencies. Individuals were assigned to the correct species with an accuracy of 80%, indicating that each species exhibits species‐specific patterns of behaviour. D. auricularis displayed more agonistic and sexual behaviour and less huddling behaviour than any of the Tatera species.

The sympatric species‐pair, T. leucogaster and T. brantsii, exhibited more significant difference in behaviour than either of the allopatric species‐pairs, T. afra and T. brantsii, and T. afra and T. leucogaster. Divergence in behaviour patterns has occurred in allopatric species, but divergence is more marked in species which are sympatric. It is not known whether divergence between T. leucogaster and T. brantsii occurred during a period of allopatry, or whether divergence has occurred due to selection against hybrids in sympatry.
Reconciling with Valuable Partners by Long‐tailed Macaques
Authors: Cords Marina , Thurnheer Sylvie
Published: May 2010

In primates and other social mammals, opponents in aggressive conflicts have been reported to seek one another out after fights for various types of friendly interaction. In long‐tailed macaques, these friendly reunions have been shown to restore aspects of the social relationship of the opponents to their preconflict state, and they have thus been interpreted as reconciliations. Although postconflict reconciliation would seem to be adaptive to gregarious animals that establish individualized social relationships, its occurrence is variable among species, groups and dyads. Some of this variation probably reflects costs and benefits of reconciling in different situations. One factor that might influence the benefit of reconciliation and hence its occurrence is the value of the social partner as a social or ecological resource: reconciliation should occur more often after fights with valuable social partners. We conducted an experiment to test this hypothesis using pairs of monkeys (Macaca fascicularis) as their own controls. First, baseline rates of reconciliation after experimenter‐induced conflict were measured. Then, the value of the relationship, at least in the test context, was increased by training each pair of monkeys to perform a simple cooperative task in which each got access to food only if the partner fed nearby simultaneously. Finally, the reconciliation rate was measured again after training and compared to its baseline value. In 6 of 7 dyads, the reconciliation rate increased after training, and the median reconciliation rate after training was 3 times higher than at baseline. While the results are consistent with the value hypothesis, there are other potential explanations. Comparison of friendly behavior when there had been no prior aggression in baseline and post‐training phases, however, suggested that the increase in reconciliation rate was neither the result of a general increase in compatibility nor the result of anticipated conflict in the cofeeding context.
Food Storage in Gray Jays: Source Type and Cache Dispersion
Authors: Waite Thomas A. , Reeve John D.
Published: May 2010

Animals that store food items in scattered sites must decide how to distribute their caches in space. Our theoretical approach is based on the assumption that such animals disperse their caches in a manner that maximizes the long‐term rate of storage of recoverable (surviving) food items in the habitat. We investigate the cache‐spacing behavior of theoretical scatter hoarders that encounter food sources differing in the energetic content of the items they contain. We then describe a field experiment in which gray jays (Perisoreus canadensis) were presented with both small‐ and large‐item food sources. The jays compensated for source type by spacing larger‐item caches more widely, a compensation that would tend to yield a high rate of storage of recoverable food energy over the long term and throughout the territory. Previous models do not adequately account for the observed patterns of cache dispersion.
Diving‐for‐Food: A New Model to Assess Social Roles in a Group of Laboratory Rats
Authors: Krafft Bertrand , Colin Catherine , Peignot Patricia
Published: May 2010

In an experimental situation called “diving for food”, groups of laboratory rats are tested in an aquarium where they have to dive and swim under water to reach the single source of food located at the other end. A behavioural differentiation appears: some rats — the carriers — dive to get food and others — non‐carriers — stay in the cage and feed by stealing. We examine whether carrier and non‐carrier profiles can be considered as social roles, defined as supraindividual features dependent on the social context. Carrier/non‐carrier differentiation resulted in all groups tested. Individually tested, almost all rats can get food by diving and swimming. Differentiation also occurred in groups that had been previously trained alone in the device, and in groups whose members had all been carriers or non‐carriers exclusively in a preliminary stage. As the access‐to‐food behaviour of a rat having to cope with the diving‐for‐food situation is settled by its social environment, we consider that the present experimental model is promising for the study of interactions between the individual and the social structure.
Behavior of Colonial Orb‐weaving Spiders during a Solar Eclipse
Authors: Uetz George W. , Hieber Craig S. , Jakob Elizabeth M. , Wilcox R. Stimson , Kroeger David , McCrate Andrea , Mostrom Alison M.
Published: May 2010

The behavior of colonial orb‐weaving spiders (Metepeira incrassata) in tropical Veracruz, Mexico was studied during the total solar eclipse on July 11, 1991. Spiders behaved in a manner typical of daily activity until totality, when many began taking down webs. After solar reappearance, most spiders that had begun taking down webs rebuilt them. There was no significant difference in the overall activity patterns of spiders during totality across a range of colony sizes. Experimental illumination of part of a colony during totality altered web takedown behavior. While spiders in the darkness of totality began to take down webs, those spiders which were artificially illuminated did not. These observations suggest that the primary environmental cue responsible for the daily rhythm of web building behavior in this species is light level.
Male Choice and Male‐male Competition in Idotea baitica (Crustacea, Isopoda)
Authors: Jormalainen Veijo , Merilaita Sami , Tuomi Juha
Published: May 2010

Sexual 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

We 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

The 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

Size‐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

Male 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

The 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

Acoustic 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

In 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

Under 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

A 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

Night‐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

This 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

Management 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

Management 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

The 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

In 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

Acoustic 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.
Effect of Male Competition on Male‐Female Relationships in Bi‐male Groups of Mountain Gorillas
Authors: Sicotte Pascale
Published: May 2010

In gorillas (Gorilla gorilla beringei), male reproductive competition is manifested during inter‐group encounters through displays and contact aggression with opposing males and through attempts to control the movement of females between groups. This paper documents the effect of within‐group male reproductive competition on male‐female relationships. In one‐male groups, females are known to take the initiative in the maintenance of their relationships with males. In two‐male units, because males face within‐group reproductive competition, one can expect a reversed pattern of responsibility for proximity maintenance. Three measures were used to assess responsibility for proximity maintenance: Hinde's index of proximity: the proportion of ‘follows’ and ‘neighing’. The proportion of follows is the number of follows in relation to the number of departures within each dyad. Neighing is a vocalization emitted by males towards departing females. It is used as a measure of males' motivation to negotiate proximity with females. The data come from focal observations on the silverbacks and ad libitum data collected over 8 months (380 h in 1989) at the Karisoke Research Center. Results indicate that within‐group reproductive competition in itself does not lead to a reversed pattern of responsibility in proximity maintenance between males and females, but that the stability of the dominance relationship between the males, and the quality of the relationship between males and females, might have a role to play as well. Results on the neighing vocalization suggest that males are eager to negotiate proximity with cycling females rather than with lactating or pregnant females.
Effects of the Cestode Schistocephalus solidus on Food Intake and Foraging Decisions in the Three‐spined Stickleback Gasterosteus aculeatus
Authors: Cunningham Emma J. , Tierney Jayne F. , Huntingford Felicity A.
Published: May 2010

Food intake, feeding efficiency, prey profitability and diet choice were examined in wild‐caught three‐spined sticklebacks, Gasterosteus aculeatus, infected with the cestode Schistocephalus solidus. Infected fish ingested significantly fewer chironomid larvae (bloodworms) before becoming satiated and handled prey for significantly longer than did uninfected fish. This was especially marked when fish had partially‐full stomachs. For uninfected fish, large bloodworms were more profitable than smaller ones, regardless of level of satiation. The two prey sizes were equally profitable for infected fish with empty stomachs. However, for infected fish that had already consumed one prey item, smaller bloodworms were more profitable; prey profitability was negatively related to relative size of the parasite. When offered a choice between large and small bloodworms, uninfected fish consistently chose the larger. Infected fish with empty stomachs were unselective with respect to prey size, but after eating just one prey item, they showed a significant preference for the smaller prey.
Can Dominance Hierarchies be Replicated? Form‐ re‐form Experiments using the Cockroach (Nauphoeta cinerea)
Authors: Dugatkin Lee Alan , Alfieri Michael S. , Moore Allen J.
Published: May 2010

Although stable hierarchies have been documented in a wide variety of species, virtually nothing is known about what occurs when a hierarchy is disrupted, and the group is subsequently re‐formed. How likely is it that the same hierarchy will re‐form? This attribute, which we quantify using a measure we call replicability, may provide insight into the processes governing hierarchy formation and maintenance. We examined replicability in the cockroach Nauphoeta cinerea. A total of 11 groups, with four males in each group, were subjected to this formation and re‐formation process. Aggressive interactions, leading to an eventual hierarchy formation, were observed for 3 d. Groups were then disbanded and individuals housed in isolation for 2 d. These same individuals were then reintroduced into the same 11 groups, and observed for another 3 d. Although 10 of the 11 groups formed stable hierarchies the first time they were put together, only six of the hierarchies were replicable.

While it is difficult to pinpoint why some hierarchies were replicable and others were not, one trend emerged that might help explain the difference. Alpha individuals in replicable hierarchies participated in a lower proportion of interactions the first time groups were together than alpha individuals in non‐replicable hierarchies. Alpha individuals in non‐replicable hierarchies thus had to participate in more interactions to maintain their alpha status. The combination of such exertion, group‐dispansion, and re‐establishment of position may preclude regaining alpha status for such individuals.
Former Experience Can Modify Social Selectivity during Song Learning in the Nightingale (Luscinia megarhynchos)
Authors: Todt Dietmar , Böhner Jörg
Published: May 2010

Changes in preference for a specific song‐learning context, characterized by close proximity of a tutor, were investigated in the nightingale, Luscinia megarhynchos. Two groups of males were tutored with conspecific song for two periods, days 42 to 56, and days 57 to 71. Song types were either presented from tape alone (group A) or were played in the presence of a familiar tutor, i.e. the person who hand‐raised the birds (group B). Acquisition success did not differ between the groups for period 2. However, while males of group B acquired songs during both tutoring periods, males of group A learned only during period 2. This indicates that in nightingales the preference for a specific song‐learning context decreases during development. A comparison with an earlier study suggests that this shift is not age dependent but primarily due to auditory experience with the song patterns to be learned. Such a mechanism has also been described for the termination of sensitive phases for song learning. Because song acquisition in adult nightingales does not depend any more on close spatial proximity of a familiar tutor, a male in his first spring and later on can learn from a number of singing territorial neighbours, and by this means acquire the large song‐type repertoire typical for the species.