bluuebunny/crossref_metadata_2025 huggingface dataset:
Communication By Agonistic Displays: a Discussion
Authors: Van Rhijn Johan G.
Published: April 2008

This paper discussed the information content of threat signals. It was an attempt to explain the inconsistencies between the points of view of model-builders using game theory as a tool (represented in a paper by CARYL in 1979 in this journal), and of the (mainly field-) ethologists spending a considerable part of their time observing animals in groups (expressed for instance in the paper by BOSSEMA & BURGLER in this issue). Arguments were presented for the transfer by threat signals of both information about intentions (motivation), and information about "resource-holding potential" (strength, ownership, etc.). Individual recognition was expected to be associated with honest signals about intentions. CARYL'S deviating findings could not be attributed to an absence of individual recognition in the animals he considered. His findings could also not be explained very well by the fact that he hardly considered subtle signals, although the present paper argued that information about intentions is mainly given by subtle signals, and information about resource-holding potential by elaborate action patterns. Imperfect methods in the papers cited by CARYL were considered as the most important source for the deviations. Finally it has been discussed to what extent observational data as presented by BOSSEMA and BURGLER help in solving problems raised by the model-builders. The occurrence of frequent, short escalations has been suggested as a mechanism for preventing bluff. The evolution of graded warning-signals could be related to (1) the low cost of a warning as compared to an attack, and (2) the settlement of a conflict on the basis of differing motivations. This paper considered the possibility of heterogeneous summation of (already known) information about the resource-holding potential of an opponent, and the information about its intentions (from the displays).
Cohesive Relationships in a Cattle Herd (Bos Indicus)
Authors: Reinhardt Viktor , Reinhardt Annie
Published: April 2008

Cohesive relationships were studied in a semi-wild cattle herd and traced over periods of three to five years. It became evident that mother cows prefer their female and male progeny over non-related calves as grooming and as grazing partners. These associations could always be verified during the first three years and often during the fourth and fifth year as well, the descendants already being sexually fully mature. Comparable personal attachments also existing between siblings, the ensuing family units were strikingly stable and cohesive. Interindividual associations lasting for several years could also be found between non-related descendants of the herd but also between non-related cows. The analytical data led to the conclusion that in natural cattle herds the social structure is based on matriarchal families which in their turn are interconnected by means of friendship relationships between non-kin partners.
Vocal Recognition of Recorded Lambs Voices By Ewes of Three Breeds of Sheep
Authors: Shillito Walser Elizabeth , Hague Peter , Walters Eurof
Published: April 2008

Vocal recognition of lamb's voices by their dams was investigated in Border Leicester, Jacob and Soay sheep, using recordings of lambs voices which were played to ewes simultaneously with presentation of a moving model lamb when the lambs were 15-20 days and 40-50 days of age. The number of bleats made by the ewes during playback of own and alien lamb voices was recorded and then the number of times a ewe bleated in answer to a lamb's bleats within 2 s of hearing the lamb bleat was counted. At both age groups the ewes bleated more in response to recordings of their own lambs than to alien lambs, and answered their own lamb's bleats more than alien bleats. The frequency of the ewes bleats increased more to their own lamb's bleats than to alien bleats. The Soay ewes bleated less than the other breeds and the Jacob ewes were the most vocal.
Behavioural Differences Between Zebrafinch and Bengalese Finch (Foster) Parents Raising Zebrafinch Offspring
Authors: TEN CATE Carel
Published: April 2008

Sexually mature zebrafinch males show a sexual preference for the species which has raised them. IMMELMANN (1972 a, b) stated that such a preference develops more readily if zebrafinch males were exposed to their own species than to Bengalese finches. The explanation for this phenomenon has been the supposition that an initial bias for the own species exists which is independent of post hatch experience. This hypothesis presupposes the absence of differences in behaviour between zebrafinch and Bengalese finch parents raising zebrafinch offspring. To investigate this supposition, the parental behaviour of zebrafinch and Bengalese finch (foster)parents raising zebrafinch offspring was observed. This was done in pure pairs (male and female of the same species) as well as in mixed pairs (male and female of different species). Differences between both species were found in parental care, and in clumping, allopreening, aggressive and sexual behaviour directed to zebrafinch young; most clearly in mixed, but often in pure pairs too. These differences were present from a few days after hatching till the moment of separating parents and young at about day 57. The kind of differences gradually changed during this period. Zebrafinch young are thus not exposed to equivalent experience with zebrafinch and Bengalese finch parents. The observed differences in experience may underly the more readily developing preference for zebrafinch than for Bengalese finch. This alternative should be explored more thorougly before the initial bias hypothesis is accepted.
The Role of Silences and Elements in the Recognition of a Dialect in the Corn Bunting
Authors: Pellerin Martine
Published: April 2008

This study concerns the mechanisms of dialectal recognition in the corn bunting, Emberiza calandra. Thanks to a microprocessor which guided a synthetizer, we synthetically reproduced one of the 3 natural songs of the Claville dialect. After having tested this synthetic song on the birds of this locality, we modified, in succession, its different physical parameters. The results obtained show that the recognition of this dialect depends on both the temporal distribution of silences and on that of elements. Dialectal recognition, like specific recognition, therefore implies the association of several parameters.
Song Types in a Population of Great Tits (Parus Major): Their Distribution, Abundance and Acquisition By Individuals
Authors: Mcgregor Peter K. , Krebs John R.
Published: April 2008

This 6-year study of song acquisition in a marked population of great tits suggests that songs are learned both before and after dispersal, songs are not learned from fathers. The spatial and temporal distribution of songs in the population is also discussed. There is a decline in the proportion of the song repertoire shared with increasing distance from a male, but there is no consistent pattern of song type grouping, some songs are clumped while others are not. Size of repertoire is not related to male age. These results are discussed in relation to laboratory studies of song learning, song dialects and functional hypotheses concerning song learning.
Stereotyped Feature Variables Are Essential Constituents of Behavior Patterns
Authors: Schleidt Wolfgang M.
Published: April 2008

Based on theoretical consideration one can except that among the many variables one can measure in a behavior pattern those variables which are most stereotyped should be most useful to characterize a particular pattern. In order to explore the utility of this assumption, the relative variability of 204 different feature variables of the wet-my-lips call of the male migratory quail (Coturnix coturnix coturnix L.) was calculated and analyzed. The results show that the most stereotyped features (C.V. < 0.015) are those which constitute the rhythm of this call.
Male Activity and Female Mate Acceptance in the Mallard (Anas Platyrhynchos)
Authors: Bossema I. , Kruijt J.P.
Published: April 2008

This paper examines pair formation in wild and domesticated white mallard females in relation to differences in male courtship pressure. By rearing males of both strains with wild or white females, adult females of each strain could be confronted with courting males of the own or opposite strain. As almost all females paired with males courting them most intensively, regardless the colour type of the males, it is concluded that directed male activity is a more important factor for female mate acceptance than male plumage colouration. The implications of this finding for the interpretation of previous work on factors involved in mate selection by mallard females (SCHUTZ, 1965; KLINT, 1973, 1975, 1978 and 1980) are discussed.
The Pattern of Vocal Signals and the Information They Convey
Authors: Zahavi Amotz
Published: April 2008

1. The vocal signal is an indicator of the posture and movement (P.M.) of the signaller at the time of vocalization, hence it reveals, by an additional modality, information about the P. M. of the signaller. 2. The vocal signal is a reliable indicator of the motivation of the signaller because cheating would incur the cost of changing the P.M. away from the optimal P.M. for the real motivation. 3. Certain vocal patterns discriminate better than others small differences in the motivation of individuals. 4. The vocal signal which conveys a certain motivation is dependent on a) the strategy used to solve a particular conflict; b) the kind of reliable information which may resolve the conflict; c) the P.M. which conveys best such information; d) the vocal pattern which enables the listener to distinguish between signallers which differ slightly in their motivation.
Efficient Use of Food Patches At Different Distances From a Breeding Colony in Black-Billed Gulls
Authors: Evans Roger M.
Published: April 2008

A probability model is developed and tested to examine the hypothesis, derived from optimal foraging theory, that black-billed gulls utilize foraging sites efficiently by foraging at sites close to the colony when these are available. One hundred and nine inland foraging sites were located. Only 17 (20 % ) of 86 sites measured were used for more than 3 consecutive days. Use of 46 foraging sites by birds from the main study colony was documented by direct observations of foragers commuting between the colony and foraging sites. For these sites, the distance from the colony ranged up to 11.9 km (mean = 4.7 km). The daily pattern of foraging site use in relation to distance from the colony correlated with the pattern predicted by the optimality model, but differences in detail were evident. Departures from predicted foraging distances appeared to relate more to errors in the main assumptions of the model as applied to a field context, rather than to any obvious failure on the part of the gulls to utilize food sites efficiently.
Behavioural Significance of Duet Interactions: Cues From Antiphonal Duetting Between Males (Cossypha Heuglini H.)
Authors: Hultsch Henrike
Published: April 2008

Antiphonal duetting is regarded as a formalized interaction display between, usually mated, individuals of different sex. Proceeding from observations that antiphonal duetting can also occur between male conspecifics, we investigated the structure and context dependance of the display in aviary kept male robin chats (Cossypha heuglini H.). In the male/male duets, which were confined to a particular dyad of our tests subjects, all characteristic features corresponded to those of the male/female display (Fig. 1). Duet roles were not exchanged between males, and the "female" contribution was exclusively delivered by the younger male. Duetting obviously influenced both, interactions within the dyad (in terms of inhibiting overt aggression) and the territorial behaviours (attacks, chases) towards third introduced conspecifics. During confrontation with such males, the duetters took different roles in attempting to deter an outsider (test 3), which were similar to those observed for mated individuals of a pair. In tests where only one individual could attack, duet rates and attack rates were positively related (Fig. 4). Preceding a duet performance, one male approached the other one (Fig. 3), and restriction of such proximity (tests 1s, 2s) lowered both, duet rates and attack rates against an introduced male (Fig. 4 & 5). Our results allow to discuss relationships between duet behaviour and alliance formation in our males. To our knowledge such a cooperation, though presumably temporary, has not been described for adult males of highly territorial bird species.
The Influence of Social Relations On the Development of Species Recognition in Zebra Finch Males
Authors: Ten Cate Carel
Published: April 2008

The influence of social relations on the development of species recognition ('sexual imprinting') in zebra finch (Z) males was examined. This was done with Z males raised by mixed pairs of Z and Bengalese finches (B)(♂Z♀B or ♀Z♂B). During rearing, the behaviour of parents and sibling towards the young Z males was measured. Z males raised by mixed pairs were usually exposed to more parental behaviour, contact behaviour and aggression by Z (parent and sibling) than by B. These males also preferred a Z over a B female later on, which might be a consequence of differences in behavioural interactions with Z and B. In a series of experiments the amount of different behaviour patterns shown by the Z parents towards young Z males was decreased. This led to a shift from Z to B in the later preference of these males, in spite of the fact that 'visual exposure' to Z was maintained as much as possible. Influence of the sibling was examined by comparing the preference of Z males raised with a B sibling with that of Z males raised with a conspecific sibling. The effect of the sibling on the later preference, if any, appeared to be marginal to that of the parents. Preference differed between males raised by ♀ Z♂B pairs and males raised by ♂Z♀B pairs, the latter being more B directed. Experiments indicate that this difference is most likely due to lack of familiarity with female Z characteristics in males raised by ♂Z♀B pairs. The results strongly suggest that behavioural interactions between a young Z male and other birds, rather than visual exposure only, influence the later preference of this male. Several mechanisms which might underlie this effect on the developmental process are discussed. No initial preference for Z characteristics has to be assumed to explain that Z males raised by mixed pairs normally develop a Z directed preference.
Spatial Proximity Between Allies: a Territorial Signal Tested in the Monogamous Duet Singer Cossypha Heuglini
Authors: Hultsch Henrike , Todt Dietmar
Published: April 2008

In bird species in which territories are defended by both sexes, 'showing up together' is a widespread behaviour of mated individuals. To test whether the spatial proximity of simultaneously appearing mates would have a territorial signal function we presented robin chats (Cossypha heuglini H.) to mounts of conspecifics placed within their territories, Experimental variables were (1) distance between mounts, and (2) number of mounts. Results: Compared to single mount presentations, residents did not show significant differences in agonistic approaches towards the 'intruders', when mounts were positioned with a distance of 3-6 m to each other (spaced presentations). In contrast, when the distance between mounts was 0.3-0.6 m, (close presentations, simulating the close perching of mates) residents approached them significantly less often and less close (Tables 1 and 2). Such approach and attack inhibitions were not stronger when three or four mounts were offered instead of two. Residental pairs spent more time in non-vocal display behaviours than did single residents (Table 3). During playback of conspecific song after having been presented to a mount test, the residents' responses appeared to be influenced by whether they had received a spaced or a close mount test before. Our results have demonstrated the significance of visual pair recognition through clues from spatial proximity of birds. As with the vocal duet displays, the close perching of pair members may function in signalling cooperation during territorial confrontation with conspecifics.
Aggression, Copulation, and Differential Reproduction of Deer Mice (Peromyscus Maniculatus) in a Semi-Natural Enclosure
Authors: Dewsbury Donald A.
Published: April 2008

This study was designed to analyze the interactions of priority of residence, strain, dominance, male capacity, and sperm competition in relation to aggression, copulation, and differential reproduction in deer mice (Peromyscus maniculatus). Males were wild-type or blonde mutants; females were of the recessive blonde phenotype. There were 20 replicates of a procedure entailing 7-day runs. One male was introduced into a seminatural enclosure on Day 1 and the second male on Day 3. Their interactions were sampled on Days 3-7. In addition, two estrous females were introduced for tests on Day 5 and 6. In the absence of females, levels of male-male aggression were lower than in their presence. Priority of residence led to increased levels of chasing by males. Limitations on male capacity were revealed as decreased numbers of ejaculations and chases in the second of the two tests with females. Dominance was established in 13 of the 20 runs; copulation occurred in 28 of the 41 tests. Dominant males achieved more ejaculations than subordinates. Males copulated with both females on 20 of 41 occasions, with most partner changes (but smaller percentage per opportunity) occurring within ejaculatory series. Females copulated on 44 of the 82 occasions and delivered a total of 30 litters. Determinants of differential reproduction were diffuse.
Courtship Sequences and Ethological Isolation in Two Species of Sunfish (Lepomis Spp) and Their Hybrids
Authors: Clarke Susan E. , Colgan Patrick W. , Lester Nigel P.
Published: April 2008

The role of courtship behaviour in ethological isolation was studied by analysing courtship sequences between different crosses of pumpkinseed (Lepomis gibbosus), bluegill (L. macrochirus), and their hybrid sunfish. Crosses were established in large laboratory tanks, under an artificially advanced photoperiod and temperature regime, and in outside pools. Male-female interactions were filmed and videotaped. In the field, underwater films of naturally occurring courtship and spawning were taken. A behavioural repertoire was described and the data converted to pairs of male and female acts (dyads). Two contexts were distinguished (spawn and nonspawn) depending on whether courtship led to spawning or not. Several methods of analysis were used. Multidimensional contingency table analysis with factors of preceding act, following act, and cross, enabled examination of the dependence of the response of any individual (sex or species) upon the species of partner. Multidimensional Scaling of the crosses, based on a chi-square measure of overall dissimilarity for each context, revealed the relative proximities among the different interspecific and hybrid crosses and the parentals. The results generally agreed well with those produced by a clustering technique. The conclusions are: (1) The differences between the courtship and spawning behaviour of the parentals are evidence for a behavioural isolating mechanism. (2) Interspecific and hybrid crosses tend to be intermediate to parentals. (3) Courting and spawning behaviour is different in the laboratory and field environments. (4) Hybrids likely originate from crosses of male bluegills and female pumpkinseeds.
The Development of Mate Choice in Zebra Finch Females
Authors: Ten Cate Carel , Mug Gerry
Published: April 2008

SONNEMANN & SJÖLANDER (1977) found that zebra finch females raised by their own species (Zz females) differ in mate preference from females raised by Bengalese finches (Zb females) when given the choice between a Z male and a B male. Their data also showed an own species bias (Zz females strongly preferred Z males, whereas Zb females showed about equal interest in Z and B males). Several authors mentioned the existence of a preference for species-specific characteristics independent of early experience (a so called 'innate' preference) as a cause for an own species bias. This conclusion can be doubted for theoretical and methodological reasons and the question for the processes leading to an own species bias in zebra finch females seems completely open. We investigated several possible causes of the own species bias. Our experiments suggest that the final preference in Z females may be influenced by three independent processes. First, visual stimuli are involved. Information on these seems to stem exclusively, or at least largely from parental influence. No initial preference for visual characteristics, independent of experience with Z or B has to be assumed. Second, experiments indicate that a preference for actively courting males is present. The process underlying this is unknown but seems independent of the one giving rise to a preference for visual stimuli. Third, during the period between raising and testing (during which the females were visually isolated) the preference changes with age. Here too, the underlying process is unclear. Several possible causes for this change are discussed. The process underlying it is probably different from the other two. Altogether the results indicate that the own species bias may be the result of several independent developmental processes, which in combination led to a bias in testing.
Courtship in Drosophila Melanogaster: Behaviour of Mixed-Sex Groups in Large Observation Chambers
Authors: Ewing L.S. , Ewing A.W.
Published: April 2008

1. Mixed-sex groups of Drosophila melanogaster were observed in chambers sufficiently large to allow females to decamp during courtship. 2. There were two main experimental classes; one OVR, consisting of groups of four males and four virgin females (octet with virgin receptive females) the other, SVR comprising four males and two virgin females (sextet with virgin receptive females). Supplementary information was obtained from a third group, SMU (sextet with mated females) consisting of four males and two mated females. 3. Quantitative information was obtained on a number of courtship parameters which could then be compared with information from single pairs of the same Drosophila stock in the small cells normally used for courtship studies. 4. Courtship in groups was observed to consist of a number of short bouts (OVR: 14 s., SVR: 7 s.) interspersed with longer periods of non-courtship (OVR: 20.9 s., SVR 23.1 s.). Females could be courted by one or more of the available males and could mate with a male initially rejected. The shorter courtship bouts in SVR groups appeared to be related to increased interference between courting males which resulted in females terminating the bout. 5. This general pattern of courtship differed considerably from the pattern in small cells where females received a single continuous bout of courtship, consisting of 41 % vibration and lasting on average, 130 s. until copulation. In the group situation vibration comprised only 24% of each courtship bout and there were a number of gaps in courtship before copulation occurred. The overall mean courtship times including breaks were 399 s. (OVR) and 511 s. (SVR). 6. A detailed analysis of the observations on the groups in the large chambers showed that virgin females terminated the majority of bouts and did so by flying off or moving off. These elements alone of the so-called rejection responses listed by other authors appeared to have a rejection function. No function could be attributed to the other responses which may be in part an artefact of small observation cells. 7. Female decamping was not preceeded by a specific act by the male but could occur anytime during following/orientation and vibration. It rarely occurred after licking or attempted copulation. 8. The courtship of successful males differed from that of unsuccessful males only in that more time was spent courting the female eventually mated; bouts being longer and more numerous.
Some Notes On Factor Analysis of Behavioral Data
Authors: Short Robert , Horn John
Published: April 2008

The use of factor analysis with behavioral data is examined critically. Although there are good reasons to make wider use of factor analytic techniques in behavioral research, several important pitfalls should be avoided. Samples should be of adequate size, both absolutely and relative to the number of variables analysed. Variables should be reliable and devoid of scoring dependencies. One should not allow the same components to appear in different ratio variables, difference scores and composites. Variables and subjects should be carefully selected to represent a substantive design for the study. Ideally this design should stem from empirically-based, well reasoned theory. Careful thought should be given to the question of the number of factors to extract. Rotation of factors should be based on the model reflected in the design for the study. One should be wary of using mathematical-statistical indices with factor coefficients. The correlation, as such, and the standard error for a correlation, do not have the same properties when applied to arrays of factor coefficients as when used with free-to-vary numbers.
Olfactory Interactions Between Sexually Active Males in Adoxophyes Orana (F.V.R.) (Lepidoptera: Tortricidae)
Authors: Bijpost S.C.A. , Thomas G. , Kruijt J.P.
Published: April 2008

Males of the summerfruit tortrix moth, Adoxophyes orana, placed in a windtunnel react to the odour of females with upwind walking, non-orientated wing fluttering and orientated fluttering. When groups of three males were arranged linearly in an air stream there was a decline in the last two sexual activities from upwind to downwind. As this was not found to be due to increasing distance from the pheromone source, it was concluded that upwind males inhibit the sexual behaviour of downwind males. The signal responsible for this inhibition proved to be an olfactory one. This inhibition was only seen when the upwind males were (1) sexually activated and (2) in a potentially competitive situation. Males perceiving male pheromone modify their behaviour by increasing the lateral component of their search path. This behaviour could increase the probability of finding another female in natural circumstances.
Variation in the Mating System of a Biparental Cichlid Fish, Cichlasoma Panamense
Authors: Townshend T.J. , Wootton R.J.
Published: April 2008

Cichlasoma panamense is a biparental, substrate-spawning cichlid which breeds during the dry season in Panamanian streams. In one population some males helped to defend their offspring throughout the period of parental care but many deserted their mates to achieve additional spawnings leaving females to guard alone. The proportion of C. panamense guarding in pairs increased throughout the breeding season. This was associated with an increase in the rate with which parental cichlids attacked potential brood predators and an increase in brood size. The increase in attack rate was due to the crowding of fishes as water levels receded during the dry season and especially to the increasing numbers of newly independent cichlids which congregated in the shallow water areas where C. panamense brood. The sex ratio in the population was strongly biased towards females. Males spent more time away from the brood than females which enabled them to find and spawn with unmated females. The attack rate of females brooding alone was not significantly higher than that of those with mates and their foraging rate not significantly lower although they spent less time away from their brood. In a more productive stream where population density was high, breeding was almost entirely in monogamous pairs. The rate at which parents attacked potential predators was higher, the sex ratio was 1:1 and brood size was large. The male's decision to guard or desert appears to depend on his opportunities for further matings, the ability of the female to guard alone and the value of a current brood. These results agree with the predictions of game theory models of parental care.
Individual Contributions To Cooperative Behaviour in the Acorn Woodpecker: Effects of Reproductive Status, Sex, and Group Size
Authors: Mumme Ronald L. , De Queiroz Alan
Published: April 2008

Acorn woodpeckers (Melanerpes formicivorus) are communal breeders that live in permanently territorial family groups of 2-15 individuals. All group members participate in several forms of cooperative behaviour, which we define as the investment of resources in a common interest shared by other group members (CHASE, 1980). Acorn woodpecker group interests include the caching of acorns in a specialized storage tree (the granary), maintenance of the granary, and defence of the granary against intra- and interspecific intruders. Because of a strong positive relationship between the availability of stored acorns and group reproductive success, investments in acorn storage, granary maintenance, and granary defence have a direct positive effect on the individual fitness of breeders. Non-breeding helpers, however, do not realize a direct reproductive reward, and therefore profit less directly from investment in these forms of cooperative behaviour. Thus, we predicted that breeders should invest more heavily in cooperative behaviour than should helpers. The prediction was upheld: for nearly every form of cooperative behaviour examined, breeders contribute significantly more than do helpers. On the other hand, while established breeders only rarely intrude on neighbouring territories, nonreproductive helpers frequently do so. These dispersal "forays" constitute attempts by helpers to locate ecologically restricted breeding vacancies. The effect that group size has on individual contributions to cooperative behaviour is unclear. Individual rates of acorn storage decrease significantly with increasing group size, but granary attendance and granary maintenance do not. Male and female acorn woodpeckers do not differ in their contributions to acorn storage, granary maintenance, or interspecific defence. Females, however, play a significantly greater role in intraspecific defence because of a female-biased intruder sex ratio and sex-specific defensive behaviour.
Integrity of a Red Deer Stag Group During the Velvet Period, Association of Individuals and Timing of Antler Cleaning
Authors: Bartos Ludek , Perner Vaclav
Published: April 2008

Previous studies on a "white" red deer herd at Zehušice, Czechoslovakia showed that a stag's antler casting and cleaning dates were related to his rank in the dominance hierarchy. The relationship was less apparent with antler cleaning than with casting. It was suggested that this is a consequence of disintegration of the bachelor group during the period of antler growth. A group of 14 individually recognised stags in a 1.26 km2 enclosure were observed 77 times between March 15th and August 22nd 1983. The number of stag groups, the distribution of stags into groups and the number of solitary stags was recorded on each occasion. For each observation the "relative dominance index" (RDI, rank position within a group divided by the number of stags in the group) was calculated for each individual. Correlation coefficients between antler cleaning dates and summed RDI values were calculated. As in previous seasons, and in contrast to the period preceding antler casting, the bachelor group disintegrated during the velvet period. As antler cleaning approached the stags tended to disperse into more groups and separate from other deer. The stags associated with others of similar rank and age. There was a close association between summed RDI values for individual stags for the last two weeks of the velvet period and dates of antler cleaning. Among pairs of stags which were closest associates during this period, the higher ranking stag always cleaned earlier. It is concluded that the disintegration of the bachelor group in the period before antler cleaning may be the major factor which causes a less apparent relationship between rank and the date of antler cleaning than between rank and date of antler casting. It is suggested that these two points in the antler cycle are regulated by hormones modulated by agonistic behaviour related to rank.
Structure of the Dominance Hierarchy and Dominance Determining "Group Factors" in Melanochromis Auratus (Pisces, Cichlidae)
Authors: Nelissen Mark H.J.
Published: April 2008

Two questions are asked: (1) Which relation is there between the dominance hierarchy and communication? (2) Which are the dominance determining factors that are a result of group life ("group factors") and that cannot be found in pairs of animals? Melanochromis auratus, a cichlid fish from Lake Malawi, is studied under laboratory conditions as a representative model. Dominance relations in pairs of animals differ from those (between the same fishes) in groups of conspecifics. In groups M. auratus establishes and maintains a linear dominance hierarchy, of which the communicative structure is described and discussed. The number of aggressive interactions between two group members, is determined by the rank number of the actor and the reactor. Most interactions occur between rank neighbours. "Group factors" are looked for by analysing the clustering of all possible chase-interactions. Four categories of such clusterings are discussed: a preceding aggressive interaction can have an influence on high-ranked animals, the effect of such an influence is directed towards low-ranked animals. The stable hierarchy can be changed by successive circle fights. The highest-ranked group members always intervene in circle fights in order to stabilize the hierarchy, for their own benefit. This is another "group factor". An alpha animal has to spend all its energy in obtaining and maintaining its rank status. When it looses this position, it drops down the hierarchy. The benefit of the alpha place could be the reproductive succes.
Conflict and Cooperation in the Group Feeding of the Social Spider Stegodyphus Mimosarum
Authors: Ward Paul I. , Enders Margit M.
Published: April 2008

1. Stegodyphus mimosarum, a social spider, lives in colonies which may contain hundreds of individuals. Feeding behaviour was examined with respect to feeding group size and prey size. 2. Prey were less likely to escape and were subdued more quickly when attacked by more than one spider. 3. During capture small prey were frequently bitten directly on the body whereas large prey were almost always bitten on an appendage. 4. Pulling struggles for subdued prey occurred. They lasted longest over medium sized prey. Small prey were easier to transport to the nest than medium prey and large prey were pulled by more spiders from a single retreat. 5. Spiders which had participated in a capture initially bit preferentially on the prey's head or thorax but others which joined later to feed bit at random. 6. Feeding became less efficient as group size increased and an experiment suggests that individuals injected less poison and digestive enzymes when feeding in groups.
The Social Food-Flow Within the Colony of a Stingless Bee, Melipona Favosa (F.)
Authors: Sommeijer Marinus J. , De Bruijn Luc L.M. , Van De Guchte Cees
Published: April 2008

Trophallaxis in workers of stingless bees was studied in colonies of Melipo favosa with marked individuals. In the brood area of the nest all trophallactic interactions are initiated by the soliciting bee, whereas spontaneous offerings occur particularly near the nest exit. The trophallactic network within the colony does not represent an open system that leads to even distribution. The cell-provisioning bees obtain food, mainly from other bees. Since cell-provisioning is strongly age-dependent, the trophallactic benefit changes strongly according to the age of the bees. The bees that discharge on a particular day are not involved in the pollen uptake from food pots on that day. The dischargers probably obtain trophallactically a liquid food suspension with a high pollen content, which they subsequently regurgitate into the brood cells. The dischargers also perform active food solicitations with other bees immediately after they have discharged during the progress of the provisioning of a cell. For this they often depart quickly from the cell that is being filled. We assume that their withdrawal from the cell vicinity enhances their chances to meet quickly bees that are less reluctant than the other dischargers nearby to donate food to them. This behavior sometimes enables dischargers to perform subsequent regurgitations in the same cell.
The Effects of Predation Risk and Group Size On the Anti-Predator Responses of Nesting Lapwings Vanellusvanellus
Authors: Elliot Richard D.
Published: April 2008

The anti-predator responses of nesting lapwings were studied near Newburgh, Aberdeenshire, Scotland, using taxidermy mounts of a carrion crow, great black-backed gull, and red fox pulled towards their nests. Lapwings appeared to respond to these dummies and to a control woodpigeon as they would to the live animals. Responses to nest predators that are relatively harmless to adult lapwings, represented by the crow, included initial investigative flights. These quickly changed to diving attacks, over 60% of which actually struck the dummy predator. In response to the fox, which is a threat to both the adults and the eggs, lapwings never made physical contact, but circled overhead, or attempted to lead or distract the predator on the ground. Responses to the fox were similar in daylight and darkness, but lapwings did not respond to the dummy crow at night. Both diving and distraction responses to the gull were observed. Thus the closeness of attack was inversely related to the risk that the live predator would have posed to the adults. The intensity of response to the dummy crow increased through the incubation period and breeding season, as predicted on the basis of a decreasing difference between the reproductive value of the adults and the clutch they were protecting, resulting in the defenders under-taking increasingly greater risks. Both the number of lapwings responding to the crow, and the distances from the nest at which high intensity responses occurred, increased with the size of the nesting aggregation, ranging from one to five pairs, but not with the number of birds present prior to the experiment. Both these effects should lead to a higher probability of successfully repelling a crow with increasing group size. The area in which diving attacks occurred extended to 40-60 m from the nest in larger groups. Neither relationship was found in experiments with the dummy fox, in which all high intensity responses were performed by one adult only. Nesting in loose aggregations thus seems to enhance the effectiveness of the lapwings' responses to nest predators such as crows, but not to more dangerous predators such as the fox.
Time-Budgets of Camargue Horses Iii. Environmental Influences
Authors: Duncan Patrick
Published: April 2008

1. Time-budgets of female, male and yearling horses were calculated for 34 weeks over two years. There was little variation in the time spent in different activities during autumn and winter (Aug.-Mar.). 2. The horses spent more time lying (sleeping) in spring, when on a high protein diet. In summer they spent more time standing alert and walking, less feeding, probably because of the attacks by biting Diptera. 3. Within autumn and winter standing alert decreased when mosquitoes were abundant and standing resting, usually in shelter, increased on days with low maximum temperatures and during rain. Feeding time was unaffected by these variables. 4. The breeding mares increased their feeding times during periods of nutritional stress (end of winter, peak lactation) but only by 6-8%. 5. The time-budgets of these horses showed less variation than has been found in some ruminants. It is argued that for most of the year their feeding time is close to the maximum value allowed by the need to perform other activities, principally resting and moving.
Categorisation of Interpulse Intervals and Stochastic Analysis of Discharge Patterns in Resting Weak-Electric Mormyrid Fish (Gnathonemus Petersii)
Authors: TEYSSÈDRE Claudine , Boudinot Michel , Minisclou Catherine
Published: April 2008

Inter-individual similarities in the electric organ discharge activity of immobile, isolated and undisturbed mormyrid fish were investigated. Two types of analysis were performed on the discharge patterns of 10 Gnathonemus petersii: (1) The Bout Interval Criterion method was used to categorise the intervals between consecutive electric pulses; (2) an analysis of sequences of acts was performed to study the serial ordering of the interpulse intervals. Interpulse intervals were demonstrated to belong to distinct classes, having similar limits for most animals. Most fish show five classes of interpulse intervals (23 to 68 ms; 69 to 108 ms; 109 to 170 ms; 171 to 212 ms; >212 ms), to which a sixth class (<23 ms) is added in some cases. Each class contains a similar number of intervals in all individuals. Particular associations were found between the occurrences of interpulse intervals belonging to different classes. Some of these associations (for example BB and EC) are displayed by most fish, whereas others express individual differences in the patterns of discharge. The discharge of immobile, undisturbed, isolated mormyrid fish is thus shown to present many similarities among individuals. Inter-individual differences exist only in the serial ordering of the intervals, where they arc best regarded as variations around a same theme. The absence of overlapping between the two main categories of interpulse intervals (category I: 69 to 108 ms; category II: 171 to 212 ms), as well as the constancy of their baselines, suggest that two oscillating systems participate to the electromotor command. The stochastic analysis of the serial ordering of the interpulse intervals suggest in addition that these two oscillators do not function independently. Momentaneous modifications of the activity of these two oscillators would provide an economical explanation for the various changes in the types of interpulse intervals associated with behavioural state or social interactions.
Predictions From the Ranging Hypothesis for the Evolution of Long Distance Signals in Birds
Authors: Morton Eugene S.
Published: April 2008

The Ranging Hypothesis (RH) (MORTON, 1982) proposed a form of distance assessment (ranging) based upon perception of signal degradation using memorized signals as a yardstick to distance. The predictions of the RH include distance assessment mechanisms, DAMs; it is proposed that these have opened a new evolutionary process illustrated by the complicated songs and singing behaviour in the oscine passerines ("songbirds"). The RH identifies sources of selection favouring learning, multiple or single song types, song structural complexity not accounted for by species isolating mechanism ideas, and emphasizes the ecological basis for the evolution of long distance communication. New importance is given to the acoustic physical structure of songs. The RH encompasses and contrasts song evolution in warm climate regions with those in cold temperate climates. Three interrelated stages of long distance signal evolution are presented: detectability, threat, and disrupt. A singer/listener role dichotomy in selective pressures is described and the results discussed. Listeners developed distance assessment mechanisms (DAMs) resulting in an evolutionary arms race between listeners and singers. Singers developed methods to use DAMs to their best interest (threat and disrupt). Song learning in passerines developed in response to this arms race to enhance disruption, a situation most prevalent in cold temperate zone regions. The acoustic determinants of effective song distance are described and discussed in relation to the evolution of signal structures. Finally, the RH is discussed in relation to some previous hypotheses on song function and evolution.
Distraction, Decisions and Persistence in Runway Tests Using the Domestic Chick
Authors: Andrew R.J. , Klein R.M.
Published: April 2008

Androgens appear to cause reduced distractibility and increased focussing of attention in a number of species of mammals and birds. It is here shown, using runway tests, that in the domestic chick the changes in attention produced by testosterone are diverse, affecting on the one hand processes following immediately after perception, and on the other the allocation of attention between different stimuli over quite long periods of time. Examples of the first type include reduced distraction at first presentations of a conspicuous but irrelevant stimulus, increased response to change in the stimulus on which attention is focussed, and increased likelihood of fast response when a stimulus of the type which is being sought, appears in an unexpected position. All can be explained as due to an increased ability to specify stably a particular stimulus or type of stimulus as that which is being sought or on which attention is to be sustained. Longer term changes in the organisation of behaviour suggest that more than one focus of attention can be stably specified in a particular period of time. Testosterone-treated chicks will alternate attention between two very different stimuli (food and a conspicuous novel stimulus), even when one cannot be seen from the other without locomotion. It is necessary to consider the full complex of linked changes which may result from modulation of attention by hormones (or other physiological variables), in any discussion of the benefits and costs which might result.
The Influence of Group Size On Predator Scanning and Foraging Behaviour of Wedgecapped Capuchin Monkeys (Cebus Olivaceus)
Authors: De Ruiter Jan R.
Published: April 2008

The behaviour of two groups of wedgecapped capuchin monkeys, Cebus olivaceus, a small one (n = 8) and a large one (n = 25) was recorded. Time budgets and other aspects of behaviour depended on group size. The differences can be explained as: adjustment to predation risk and intra-group food competition. In order to evade predation, members of the small groups scan more and stay at greater heights than those of the large group. Higher food competition within the large group was reflected in the composition of its diet, in longer travel distances, and higher levels of social behaviour. In particular during the dry season, the large group exploited unattractive and risky food sources. These results support ALEXANDER'S hypothesis on the causes of group formation.