Showing papers in "Behaviour in 1985"

Vervet monkey alarm calls: Manipulation through shared information?

Abstract: High-ranking male and female vervet monkeys in Amboseli National Park alarm-call at higher frequencies than do low-ranking males and females. This correlation between rank and alarm-calling does not occur because high-ranking animals have more offspring or close kin than low-ranking animals. Similarly, high-ranking animals do not seem to have greater opportunities to spot potential predators; they do not scan the habitat more than low-ranking animals, nor are they more likely to be in the forefront of group progressions. It seems possible that low-ranking animals may spot predators as often as high-ranking animals, but that they do not always alert other group members to approaching danger. As a further test of the possibility that monkeys may vary the rate of alarm-calling depending on social contexts, an experiment was conducted on captive vervet monkeys in which adult females were presented with a predator in the presence of either their offspring or an unrelated juvenile. Adult females alarm-called significantly more often when with their offspring than with unrelated juveniles. A similar experiment conducted on adult males showed that males alarm-called at higher rates in the presence of adult females than in the presence of other adult males. The results of both experiments and observations suggest that monkeys may vary the rate at which they warn others of danger. The withholding of information may be an effective means to deceive others, because it is relatively difficult to detect cheaters. The possible advantages of selectivity in alarm call production are discussed.

Risk of Predation of Parasitized Sticklebacks (Gasterosteus Aculeatus L.) Under Competition for Food

Abstract: Three-spined sticklebacks which were either unparasitized, heavily infested by plerocercoids of the cestode Schistocephalus solidus, or parasitized by the sporozoan Glugea anomala were singly offered to choose between Tubifex worms at different distances from a live fish predator The uninfested fisn preferred the worms most distant from the predator and fed at a lower rate than in its absence Almost all sticklebacks infested by S solidus, however, did not react to the predator; they fed at all distances equally often and at the same rate as with no predator present Those infested by G anomala fed at an intermediate rate between healthy fish and ones carrying S solidus but stayed even farther away from the predator than uninfested fish Both the increased need for food and the reduced fleeing ability of the parasitized sticklebacks do not seem to provide a sufficient functional explanation for the behavioural changes assuming that the infested fish balance differently the conflicting demands of predator avoidance and feeding The fearless feeding of the fish infested by S solidus which has to end up in a fish eating bird and the fearful behaviour of the sticklebacks parasitized by G anomala for which the stickleback is the only host could both have been influenced by parasitic manipulation During intraspecific competition for food between a stickleback infested either by S solidus or G anomala and an unparasitized one in the presence of the predator the healthy fish were clearly outcompeted by the parasitized ones The overall competitive disadvantage of the parasitized fish can therefore be mitigated under the risk of predation

Parent-Offspring Conflict in Budgerigars

Abstract: Despite widespread theoretical interest in genetic conflict between parents and offspring, there is little empirical evidence that it exists in nature. Theoretical models suggest two outcomes of conflict not predicted by alternate theories: (1) offspring that control the allocation of parental investment might show escalated demand behaviours (e.g., begging) and demand more resources than they could efficiently use and (2) parents might evolve behavioural counterstrategies which prevented offspring from obtaining extra resources, but which were more costly than a "laissez-faire" parental strategy allowing offspring control. These predictions were tested in budgerigars, (Melopsittacus undulatus) in large flight cages at Davis, California. Budgerigar clutches hatch extremely asynchronously, yet all nestlings grew at similar rates and fledged at similar sizes and ages. This independence of hatch order and performance seemed due primarily to the mother budgerigar's allofeeding strategy: females allofed offspring mainly on the basis of size, and only secondarily attended to begging rate. Offspring of a given age and size were treated the same by their mothers regardless of hatch order, and offspring undersized for their age were fed as if they were younger. In contrast, male budgerigars attended to offspring begging rates. Males tended to initiate feeding bouts when offspring begged, and to allofeed vigorous beggers more often. Variance in male allofeeding behaviour allowed comparisons of size-matched families in which females performed nearly all of the allofeeds to nestlings (= female-fed families) with families in which males and females both allofed nestlings (= male-aided families). The parent controlled the allocation of food in female-fed families, while offspring had greater control over food allocation in male-fed families. As was predicted by conflict theory, the female counterstrategy was effective but potentially costly: the food delivery rate of females was only half as fast as males'. Conversely, offspring control resulted in an escalation of beg rate for the same degree of need (as measured by size and growth), and male-aided offspring obtained nearly three times more regurgitations than female-fed nestlings, yet grew at comparable rates and fledged at comparable sizes and ages. Hence, offspring demanded and obtained more food than they could effectively use. Other avian parents also seem to use effective but potentially costly counterstrategies, and other avian offspring may demand more food than they require. Even if initial hatch asynchronies functioned in brood reduction, the parental strategies described here would allow parents to retain control over the timing and conditions for offspring loss.

Breeder-Helper Conflict in a Cichlid Fish With Broodcare Helpers: an Experimental Analysis

Abstract: This paper reports an experimental analysis of conflicting interests in the cooperatively breeding Lamprologus brichardi (Cichlidae). Helpers clearly prefer to stay in the family territory rather than leave for an aggregation of same-size young or for an unoccupied area-even when their chances of reproducing independently are superior to those in the field. Helpers usually attain independence when the breeders force them to leave the territory. Breeders' toleration of helpers depends on the stage in the reproductive cycle, the size of helpers and the need for helpers. Large, previously expelled helpers are reaccepted when competition is increased. In these circumstances breeders prefer their own former helpers to strange young. Experimental and field evidence suggests that 3 factors are ultimately important for the breeder/helper relationship: reproductive parasitism by mature helpers, eventual cannibalism on breeders' eggs and competition for shelter within the territory. A graphical model shows how the initially common interests of breeders and helpers develop divergently when helpers reach the size at which they become sexually mature and less susceptible to predation. Large helpers pay to stay. The relationship of breeders and large helpers meets the criterion of reciprocal altruism.

The suckling behaviour of domestic pigs in a semi-natural environment

Abstract: The suckling behaviour of domestic pigs living in a socially and ecologically rich outdoor environment was examined in order to obtain a baseline for comparison with behaviour in more restricted and barren environments. It was found that the piglets' growth rates were not consistently influenced by their suckling location along the udder, and that the concept of dominance at the udder was not justified. Crowding at the udder was probably an important factor prompting piglets to seek milk and solid food elsewhere, and two piglets switched from suckling from their own mother to suckling from another sow. True communal suckling was not exhibited. Piglets were responsible for locating their preferred teat and defending it from others. Sows did not attempt to prevent familiar piglets from other litters from suckling from them, although they sometimes terminated a suckling bout when disturbed by fights at the udder. Synchronization of suckling between litters was common. Suckling bouts did not always result in milk let-down, indicating that this is not a phenomenon exclusive to intensive housing systems. Weaning occurred naturally between 60 and 100 days after birth, and its timing varied both within and between litters but was not closely linked to the amount of aggression received from the sow.

The energetics of feeding territoriality in juvenile coho salmon (Oncorhynchus kisutch)

Abstract: 1 A foraging time budget was developed for territorial, nonterritorial, and floater fish Territorial fish spend 76% of total time at the station, 3% free swimming, 13% feeding, and 5 % in agonistic activity Floaters spend 18% of their time stationary swimming, 54% free swimming, 10% feeding, and 10% in agonistic activity Nonterritorial fish spend 50% of their time stationary swimming, 43% free swimming, 2% feeding, and 3% in agonistic activity 2 Stationary swimming tailbeat frequency for the floater (43) is significantly higher than for the territorial fish (36) The floater flight tailbeat frequency (82) is significantly higher than the territorial chase tailbeat frequency (69) Normal feed tailbeat frequencies are similar for all fish groups Nonterritorial fish tend to move slowly (tailbeat frequency = 33) for all activities except normal feed 3 The total activity budgets for territorial, floater, and nonterritorial fish are 1199, 1318, and 910 cal/kg/hr, respectively The territorial fish uses 91 % as many calories as the floater fish and the nonterritorial fish utilizes 76% of the territorial budget 4 Total agonistic costs represent 12 and 14% of the territorial and floater fish activity budgets, respectively 5 The costs per feeding motion for the territorial, floater, and nonterritorial fish are 403, 491, 101 cal/motion, respectively 6 The territorial fish has a net energy intake advantage over the floater, and probably over the nonterritorial fish, due to 1) reduced search costs, 2) reduced prey pursuit costs, and 3) reduced agonistic activity costs

Gibbon Song Duets and Intergroup Spacing

Abstract: Observations sur le terrain dans la Kutai Game Reserve, Indonesie. Caracteristiques de ces duos; leurs proprietes acoustiques et leur redondance les rendent audibles a longue distance. Ils serviraient a maintenir une certaine distance entre les differents groupes sociaux chez Hylobates muelleri

Consequences of domestication on the song structures in the canary

Abstract: This study on the organization and detailed acoustic morphology of birdsong deals with the implication of domestication upon behaviour. The songs of wild canaries (Serinus canaria) and different domesticated strains of canary were studied. These included border canaries, bred for appearance in Britain and song canaries, selected for song quality in Germany. The basic rules for developing song architecture, involving rules for assembling individually learned utterances into songs emerge by self-differentiation without any auditory or feedback stimuli. By contrast, the fine structure of notes is shaped by individual learning. A comparison of songs of wild canaries and of different domesticated breeds reveals how selective breeding can alter the behavioural programmes and the general acoustic morphology of learned notes. The results of this comparison can be summarized as follows: 1. All canaries sing phrases according to an identical programme. The temporal patterning of single utterances is very similar. 2. Quantitative differences are found in the proportion of single notes and trilled sequences or tours: Single note complexes are dominant in wild canary song, whereas in the domesticated breeds tours form the bulk of the songs. This quantitative difference is responsible for a highly contrasting impression to our ears of songs that are highly variable in the wild form, and very stereotyped in domesticated song canaries. Canary breeders select strongly for longer repetitions of identical utterances (duration of tours). Border canaries, which are not selected for this trait sing short tours, far more similar to the wild conspecifics than to the song canaries. 3. Low-pitched songs are highly esteemed by bird fanciers. The maximum frequency used by song canaries is much lower than that used by wild birds. 4. One can distinguish by ear approximately ten main syllable-categories, which recur in nearly every individual repertoire. This categorization is based on differences in their acoustic properties. To assess the subjective impression that individual learning is highly channeled in a few predictable overall categories, a reproducible method to define these universal categories has been developed: Individual repertoires depicted on sonagrams were analysed by using a dichotomous key of specific song characteristics and divided into 31 classes: The frequency of use of the syllable categories by individuals with totally different song repertoires was surprisingly similar: Some classes are highly overrepresented, whereas others are underrepresented. Thus wild and domesticated canaries form their individual repertoires according a similar array of characteristics. Thus species-specificity in the general acoustic morphology is based on rules for linking variable components of notes. Individuality is an attribute of single components, such as the pattern of frequency modulation and sequential patterning. One can demonstrate that the general acoustic morphology has remained astonishingly stable during the long process of domestication. The learning process seems to be restricted to a limited set of combinations of note components. Only a few characteristics of syllables appear to have been changed by domestication: e.g. rough syllables have nearly been eliminated, whereas very short syllables (below 50 ms) have become far more frequent.

Geographic Variation in the Sexual Behaviour of the Guppy, Poecilia Reticulata (Peters)

Abstract: The guppy, Poecilia reticulata, exhibits marked intraspecific variation in behaviour and morphology and occurs over a wide range of natural environments in Trinidad, West In-dies. In this paper we examine the hypotheses that: 1) in clear mountain headstream waters in Trinidad, where Rivulus hartii is the only major aquatic predator, sexual selection has favoured the evolution of visual components of courtship behaviour in the guppy, and 2) in turbid lowland rivers with numerous aquatic predators selection has resulted in greater dependence upon non-visual components of courtship. Guppies were observed in four rivers in Trinidad. In two mountain headstreams guppies were evenly distributed across and along the river. Guppies in a lowland river and a 'midstream' river occurred in small schools close to the water's edge. Males guppies in the headstreams performed more frequent sigmoid displays and displays of longer duration than males in the turbid lowland river and the midstream river. Males in the turbid lowland river were found to exhibit higher frequencies of gonopodial thrusts than males in the other three rivers. Offspring of guppies from the four rivers were raised under identical conditions in the laboratory, free from predation and other selective agents. The results of observations of courtship behaviour in laboratory-raised fish are consistent with those obtained in the field. The overall similarity of results in the field and the laboratory provides evidence that there is a genetic basis to the observed behavioral differences between populations.

Sexual Selection in the Spring Peeper, Hyla Crucifer (Amphibia, Anura): Role of the Advertisement Call

Abstract: 1. The advertisement call of the spring peeper exhibits significant variation in each of the four parameters examined: intensity, duration, frequency, repetition rate. 2. In playback experiments involving calls differing in a single parameter, females exhibited preference for loud calls, calls with a rapid repetition rate and low frequency calls. 3. Although we had hypothesized that females would prefer long calls to short calls, they did not. We attribute this lack of preference to unanticipated differences in the sound envelope of the two experimental calls. 4. Non-random choice by females during playback experiments may have been in response to the conspicuousness of the male call, or to encoded clues pertaining to male fitness. 5. Call repetition rate is positively correlated with body size (snout-vent length) while frequency is negatively correlated. 6. Anuran growth is thought to be indeterminate, so that larger males are typically older males. As a consequence of having survived longer, large males may be more fit. 7. Since females exhibited a preference for call parameters which were correlated with body size, we had anticipated that large males would experience differential mating success in nature. A comparison of amplexed and non-amplexed males over a three year period revealed no intergroup size difference. 8. We conclude that while females may select calls indicative of size, and perhaps fitness, during laboratory trials, such choices are likely more difficult in an active breeding congregation where acoustical interference and competition may tend to obscure call variation. 9. Finally we report the presence of small, non-calling satellite males and suggest that their success as sexual parasites may have influenced the size relationship between amplexed and non-amplexed males in our study.

Conflict and Cooperation in the Group Feeding of the Social Spider Stegodyphus Mimosarum

Abstract: 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.

Suckling and Weaning in Captive White-Tailed and Fallow Deer

Abstract: Parental investment and parent-offspring conflict theories make specific predictions on the behavior of parents and offspring. Since milk is a direct and vital form of maternal investment in mammals, nursing behavior is very well suited to test such predictions. We provide such tests here, as well as a fine-grained quantitative description of the weaning process in two species of deer. Both in white-tailed and fallow deer, fawns of primiparas had a significantly higher suckling rate than those of multiparous mothers in the first few days of life (2.90 ± 0.70 vs 1.24 ± 0.21 suckles/h from 0 to 5 days in FD, p < 0.01; and 1.42 ± 0.22 vs 0.81 ± 0.08 suckles/h from 6 to 10 days in WTD, p < 0.01). In both species, in the first 10 days of lactation, suckling bouts initiated by the mother had a significantly longer mean duration than those initiated by the fawn. We found no inter-sex difference in the rate of suckling, mean duration of suckles, total time suckling (s/h), and proportion of suckling attempts that were successful, in fawns of both species, at any age from birth to 80 days. White-tailed deer single fawns were identical to twins for all the above parameters. Fallow deer mothers were much more aggressive toward alien fawns than white-tailed deer mothers were, and spent more time close to their fawns (less than 10 m, 38% of the time from birth to 80 days, compared to 12% for white-tailed deer). We propose that weaning starts at about 20 days of age in both species. This is the time when the mother terminates more than half of all suckling bouts, terminates more bouts than she initiates, and when suckles are shorter when she initiates compared to when it is her fawn that does.

Territoriality and reproductive tradeoffs in the threespine stickleback, Gasterosteus aculeatus

Abstract: To examine the reproductive costs of territoriality, male threespine sticklebacks were divided into two treatments: competitive and solitary Relative to solitary males, competitive males had longer and fewer brood cycles, higher rates of energy expenditure per brood cycle, higher motivation to court additional females in the first brood cycle, and lower amounts of parental care during the first brood cycle Thus territoriality in this species seems to effect the tradeoff between present versus future reproduction, and within present reproduction, the tradeoff between quantity versus quality of offspring

Time-Budgets of Camargue Horses Iii. Environmental Influences

Abstract: 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.

Splendid Wren Malurus Splendens Response To Cuckoos: an Experimental Test of Social Organization in a Communal Bird

Abstract: A population of cooperatively breeding, group-living splendid wrens was tested with a mounted parasitic cuckoo. At all nests with incubated eggs or nestlings, wrens attacked the cuckoo. The timing and intensity of attacks was independent of the nest day and of the age and breeding experience of the wrens. The breeding female usually spotted and attacked the cuckoo first. Her mate and the nonbreeding helpers responded to her call and mobbed and attacked the cuckoo. Response was no quicker in groups with nonbreeding auxiliaries than in single pairs. Discovery time was independent of the number of birds in a group and depended on the movements of the breeding female. Most wrens fed the young and mobbed the cuckoo. When a wren did not attack, it usually was caring for the young of another breeding female or an earlier brood. Variance in helping behavior was not closely associated with variance in the genetic relationship between helper and the breeding female or the young beneficiaries of mobbing. Use of a common territory, attendance at a nest, feeding the young, and mobbing and hitting a cuckoo were all associated cooperative activities. The main limitation of cooperative behavior in defense against the cuckoo is the same as the observed constraint on care of the young during the prolonged period of parental feeding-a conflict of interest among breeding females for care of their own young.

Sign Stimuli in the Threespine Stickleback (Gasterosteus Aculeatus): a Re-Examination and Extension of Some Classic Experiments

Abstract: 1. Both Long Island and Dutch territorial male Gasterosteus aculeatus exhibited considerable variation in their responses to dummies. Such responses were generally consistent within the same individual presented with the same dummy: male dummies evoked primarily aggressive behavior and female dummies evoked primarily courtship. However, males from both Long Island and Dutch populations sometimes directed courtship to male dummies and aggression to female dummies. 2. Males from both populations generally directed more aggression (bites) to the silver male dummy than to the dummy male bearing red undersides and blue eyes (i.e. , nuptial coloration). However, exceptional males from both populations showed the opposite trend. In trials with Dutch males in which backoffs could be measured, this behavior was more often directed to the nuptially colored dummy male than to the silver one. 3. Males from the Long Island population directed more activities, especially bites, to the horizontal dummy male than to either the headup or headdown dummy male. These males exhibited no difference in frequencies of behaviors directed to headup and headdown dummy males. Dutch males were only tested with headup vs horizontal dummy males and they too directed more activities, especially bites, to the latter. 4. Males from the Long Island population directed more courtship (zigzags and leads) and aggression (bites) to the dummy female with the greater abdominal distention, even when such distention was extreme (supernormal). Dutch males were only tested with (normally) gravid vs supergravid dummy females and they directed more activities, especially zigzags, to the latter. 5. Males from the Long Island population directed more courtship (zigzags and leads) and aggression (bites) to the horizontal dummy female than to either the headup or headdown one. Dutch males were only tested with headup vs horizontal dummy females and directed more courtship to the latter.

The Inactivity of Animals: Influence of Stochasticity and Prey Size

Abstract: As a consequence of prey capture being partly dependent upon chance, each individual may usually spend much of the day inactive even if the population is limited by its food supply. This applies particularly to species that eat large prey and thus experience considerable day-to-day variation in intake which restricts them to relatively rich habitats. Food will be found easily on most days and little time need be spent hunting although, occasionally, they will be unlucky and, despite searching all day, risk starvation. Predators of small prey can survive in environments that provide barely sufficient food as they experience little variation in intake: but they need to search all day to sustain themselves.

Forced Copulation as a Reproductive Strategy of Male Lesser Scaup: a Field Test of Some Predictions

Abstract: I presented evidence that sperm transfer can occur during forced copulation (FC) under natural conditions, and tested predictions of the fertilization strategy hypothesis, with field data from a marked population of lesser scaup breeding in southwestern Manitoba. As predicted, males directed FC attempts at fertilizable females and seemingly had tactics that increased their effectiveness in inseminating such females. Males selected older females (the more productive) when attempting FCs in 1 year of the study. FC rates were highest in the morning when chances of successful fertilization were probably highest. FC rates were positively correlated with annual variations in female reproductive effort and performance, but the exact nature of the relationship requires further study. Mate-and nonmate-defense by males and other behaviours which probably function as anticuckoldry tactics were observed. Contrary to BARASH'S (1977a) prediction, paired males attempted FCs more frequently than did unpaired males. Although pair formation through mate-switches is probably a more profitable strategy than FC for unpaired males, FC may be an important "last resort" strategy for older, experienced unpaired males late in the season. In general, my results provided strong support for the male fertilization strategy hypothesis.

The Influence of Weather On Incubation Scheduling of the White-Rumped Sandpiper (Calidris Fuscicollis): a Uniparental Incubator in a Cold Environment

Abstract: We studied the incubation scheduling of 8 white-rumped sandpipers (Calidris fuscicollis), a species in which only the female incubates. Because the female is small and nests in the high arctic, these birds are probably under more cold stress than birds nesting in the temperate zone. We examined the individual and collective effects of several weather variables on a female's incubation behaviour to ascertain what amount of the variability within a day was directly attributable to weather conditions. Birds made an average of 25.1 off-nest trips each day, averaging 10.5 min each. This resulted in spending, on average, 82.5% of their time incubating eggs. There was a clear within-day cycle in incubation scheduling; birds made more and longer trips in the middle of the day and, as a result, spent more total time off the nest in that period. Birds adjusted their hour-by-hour schedules to weather largely by altering the number of trips made, and less so by adjusting trip length. There was a circadian rhythm in recess time/h, explaining at least 11% of the variation in recess time/h. When the circadian rhythm was controlled statistically, weather accounted for an average of 38% of the explainable variation in recess time/h. The relative importance of each weather variable on the recess time/h was (in descending order of importance): wind speed, air temperature, solar radiation, barometric pressure, and relative humidity. Weather (primarily wind speed and temperature) exerted its strongest effects early and late in the bird's active day (0400-2300 h). On cold and windy days, birds increased the time spent on their nests early and late in the day, and made more trips than usual in the middle of the day, when air temperature was highest. We suggest that the incubation scheduling of these birds conformed to the long-term predictability of the daily weather cycle by following a circadian rhythm of behaviour modified by a response to concurrent weather that would have reduced egg cooling.

Individual Contributions To Cooperative Behaviour in the Acorn Woodpecker: Effects of Reproductive Status, Sex, and Group Size

Abstract: 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.

Courtship Behaviour in the Melanogaster Species Sub-Group of Drosophila

Abstract: Descriptions of courtship behaviour are given for seven members of the melanogaster species sub-group: Drosophila melanogaster, simulans, mauritiana, yakuba, teissieri, erecta and orena. A male wing behaviour not previously reported, wing extension, was observed in either 1- or 2-wing variants in all species except melanogaster and simulans. Male wing rowing, previously reported in mauritiana and teissiri, was seen in 1- or 2-wing variants in all species except melanogaster and orena. D. teissieri showed the most extreme form of wing rowing, and yakuba the widest variety of angles of wing vibration. Tapping by the male was observed in all species except simulans and mauritiana, but not always at the onset of courtship and not in every courtship. Extrusion in virgin females was observed in melanogaster and erecta, and abdomen extension in female simulans, yakuba, teissieri and orena. Female wing behaviours were observed in all species except simulans. Wing extension and wing rowing are distinct from vibration and scissoring (behaviours they strongly resemble). There is strong a behavioural connection between these pairs of behaviours, in that wing extension often leads to vibration, wing rowing to scissoring, and vice versa. A mechanical function for licking is proposed, following observation of long duration licking in yakuba. The function of licking is thought to be elevation of the female's abdomen, preparatory to copulation. The relationship between the seven species based on their courtship behaviours was examined using principal coordinates analysis. This suggests that the two cosmopolitan species, simulans and melanogaster, differ most widely in their courtship behaviour, with mauritiana being the most similar to simulans. This finding is assessed in relation to the ecology of the seven species, the role of courtship behaviour in speciation, and the reliability of inferences from behaviour in phylogenetic analyses.

Do the dummy experiments with sticklebacks support the irm-concept

Abstract: Several investigators have found it difficult to produce in systematic series of tests satisfactory quantitative data in support of the initial findings of TER PELKWIJK & TINBERGEN (1936, 1937) on the properties of IRMs supposed to be involved in evoking social responses in the three-spined stickleback. In particular with respect to the effectiveness of red in releasing aggressive responses, the results were often inconsistent ; this paper gives a survey of the data obtained. On the basis of a comparison of these stickleback data with data obtained in a study of egg-recognition in gulls (BAERENDS & DRENT, 1982), it is suggested that the inconsistencies are due to variation in the motivational state of the test fish, especially in the degree to which a tendency to escape is activated. It is argued that as a rule an experienced animal will in a particular situation not act on the basis of input from an IRM only, but in addition on relevant information encoded in the memory. It is conceived to be the principal function of the IRM to enable a naive animal to roughly identify at first encounter particular stimulus situations in its environment, which are essential to its survival. The animal would further extend its knowledge about these situations through learning. In the gulls, anxiety was found to reduce the influence of the IRM and increase the relative importance of memorized knowledge. If this conclusion may be generalized to the stickleback case, the failure of individual males in responding aggressively to red is likely to have been due to a dominant influence of memorized knowledge in anxious animals. This implies that to study the content of an IRM it has often to be 'unpacked' first, by reducing the escape factor as much as possible.

Structure of the Dominance Hierarchy and Dominance Determining "Group Factors" in Melanochromis Auratus (Pisces, Cichlidae)

Abstract: 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.

Cognition in Sticklebacks: Some Experiments On Operant Conditioning

Abstract: In this paper we are not dealing with phenomena that have an immediate bearing on the natural life of the stickleback. The conditioning experiments we want to report on are in the tradition of experimental psychology. Yet, the experiments have been carried out in an ethological vein in that they took place in a seminatural setting, aiz. a stickleback's territory in a planted tank. In this respect the experiments might be said to deal with the ethology of learning. It has been shown before that in many ways the three-spined stickleback male is rather ideally suited to experiments on operant conditioning (SEVENSTER, 1968, 1973). Since then we have embarked on a programme with the general aim to study the interaction of conditioning procedures with the natural behaviour repertoire. The male stickleback's behaviour often seems so rigidly organised that the question arises whether and to what extent it can be diverted or can be made to deviate under the impact of reinforcement schedules. Are there any limitations or constraints? If so, how are we to interpret them? In this field, we feel that sticklebacks may have much to offer.

Sensory factors involved in immediately postnatal ewe/lamb bonding

Abstract: 1. Aspects of the ewe which influence the lamb. Lambs were removed from their mothers at birth and tested under one of seven conditions : (1) with the dam in her pen, or, in a circular arena, (2) in the presence of a stationary model ewe, (3) with the same model, but moving, (4) in the presence of a large, headless and legless moving object, (5) with stimulation by the sound of recorded bleats, (6) with tactile stimulation or (7) with no stimulation. Indices of responsiveness included movements of righting and standing, approach to the model, bleating and nosing of the model or the arena. Results showed that lambs tested with the stationary model stood most slowly whereas the presence of the moving model ewe was associated with rapid standing. The groups with no experimental stimulation at all, or with stimulation by the sound of recorded bleats, also stood rapidly. Bleating of the lambs was most prevalent in the group with no stimulation at all. Lambs presented with moving models approached them more rapidly and nosed them more than did those tested with the stationary model. More than any others, lambs in the "stationary model" group were quiescent for long periods. Lambs tested in the presence of their mothers and those given tactile stimulation were consistently low in the rank order for all indices of response; in particular they stood more slowly and bleated less than groups presented with moving models. It is concluded that the dam is a composite stimulus for her lamb; she activates it when she moves but also elicits responses which reduce its early activity. 2. Aspects of the lamb which attract the ewe. Ninety Merino ewes, from each of which the lamb had been removed at birth, were tested in their own pens under one of the following conditions: (i) with their own lambs; (ii) with a warm, moving lamb model soaked in amniotic fluid and accompanied by lamb bleats, or with the same model but (iii) without movement; (iv) without warmth; (v) without bleats or (vi) without amniotic fluid. A seventh group was tested with a white bowl of warm amniotic fluid, also moving and accompanied by lamb bleats. The ewes approached their own lambs and were much more attentive to them, than to any of the models. The model which received the least attention was that (vi) with no amniotic fluid, while the 'model' which received the most was (vii) the white bowl containing amniotic fluid.

Variation in the Mating System of a Biparental Cichlid Fish, Cichlasoma Panamense

Abstract: 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.

Size Assessment and Cues: Studies of Hermit Crab Contests

Abstract: The agonistic behaviour of pairs of hermit crabs (Pagurus bernhardus) was observed in the laboratory. It was found that relative size was a reliable predictor of the outcome of a contest only when the crabs differed by at least 100% in weight. However, weight differences of 10 to 30% could be sufficient to cause differences in behaviour. It was concluded from this that whereas crabs can accurately assess small differences in weight, these differences may not be sufficient to reliably determine the outcome of contests. Other factors affecting RHP are relevant at intermediate size differences. Two possible cues for size assessment were tested: the size of the major cheliped and the size of the opponent's shell. The presence and size of the major cheliped were found to have a strong effect on contest initiation and outcome, and therefore this is likely to be a cue used in RHP assessment. The major cheliped was also found to play an important part in defensive behaviour, crabs lacking this appendage being less successful in defending their shells from attack. However, the apparent size of the opponent's shell did not seem to affect the initiation or outcome of contests. Thus it seems that crabs assess their opponents independently of the shells they occupy. It is concluded that large size differences are sufficient to decide contests. For smaller size differences other factors of RHP are important, and can override size differences. There is no evidence indicating that the defending crab can assess the quality of its oppo- nent's shell and make contest decisions based on this evidence. These data do not support the negotiation hypothesis.