Showing papers in "Behaviour in 1991"

The Effects of Leopard Predation On Grouping Patterns in Forest Chimpanzees

Abstract: [During a 5-year period, 29 interactions between chimpanzees and leopards have been observed or inferred in the tropical rainforest of the Tai National Park, Cote d'Ivoire. Chimpanzees chased away leopards in 9 cases, rescued alarm calling chimpanzees in 11 cases (in 4 of these footprints or growls of leopards were noted), 9 times leopards attacked chimpanzees, injuring 6 of them and killing 4. Two of the latters were most certainly eaten by the leopard later. Predation by leopards is estimated to be the first cause of mortality in the Tai chimpanzees and individual chimpanzees may experience a risk of predatory attack of 0.30 per year and a mortality risk of 0.055 per year. Tai chimpanzees adapt specifically their grouping patterns to food availability and to predation: with abundant food and low predation, party size increases and mixed parties are more frequent, whereas with the same food condition but with high predation, party size decreased and all-male party types increase. Comparisons with data on grouping patterns from Gombe and Mahale chimpanzees living in more open habitats support the hypothesis that this species adapts itself to leopard predation which is known to be lower in savanna habitats. The grouping patterns of the bonobo in Lomako forest seem more similar to Tai than to Gombe or Mahale chimpanzees, suggesting an analogous adaptation to high predation pressure., During a 5-year period, 29 interactions between chimpanzees and leopards have been observed or inferred in the tropical rainforest of the Tai National Park, Cote d'Ivoire. Chimpanzees chased away leopards in 9 cases, rescued alarm calling chimpanzees in 11 cases (in 4 of these footprints or growls of leopards were noted), 9 times leopards attacked chimpanzees, injuring 6 of them and killing 4. Two of the latters were most certainly eaten by the leopard later. Predation by leopards is estimated to be the first cause of mortality in the Tai chimpanzees and individual chimpanzees may experience a risk of predatory attack of 0.30 per year and a mortality risk of 0.055 per year. Tai chimpanzees adapt specifically their grouping patterns to food availability and to predation: with abundant food and low predation, party size increases and mixed parties are more frequent, whereas with the same food condition but with high predation, party size decreased and all-male party types increase. Comparisons with data on grouping patterns from Gombe and Mahale chimpanzees living in more open habitats support the hypothesis that this species adapts itself to leopard predation which is known to be lower in savanna habitats. The grouping patterns of the bonobo in Lomako forest seem more similar to Tai than to Gombe or Mahale chimpanzees, suggesting an analogous adaptation to high predation pressure.]

Behavioural Responses of Potential Hosts Towards Artificial Cuckoo Eggs and Dummies

Abstract: Responses of 33 potential host species towards a non-mimetic, dummy, cuckoo egg placed in their nest were tested (N = 372). For 22 of these species, their behavioural responses towards a dummy cuckoo placed near their nest were also tested (N = 193). The species were grouped in A) most common hosts: species which at the moment are losing out in the coevolutionary arms race with the cuckoo and which today represent favorite hosts; B) frequently-used hosts: species which at the moment are assumed to be true cuckoo hosts, but which are not so commonly used as those in group A; C) rarely-used hosts: species which would appear to be suitable hosts, but which despite of this, are rarely used. These species are assumed to be ahead of the cuckoo in the coevolutionary arms race; D) unsuitable hosts: species with a breeding biology which either prevents, or counteracts, cuckoo parasitism. They are therefore assumed never to have been engaged in a coevolutionary arms race with the cuckoo. In the most common hosts the median acceptance rate of the non-mimetic egg was 86 % , in the frequently-used hosts 33 % , in the rarely-used hosts 10 % and in the unsuitable hosts 100 %. In the most common hosts the median rate of aggression shown towards the cuckoo dummy was 50%, but the most numerous species in this group, the meadow pipit, showed aggressive behaviour in 60% of the cases. The median aggression rate both in the frequently-used hosts and the rare hosts was 100 % and in the unsuitable hosts 0%. The bluethroat was the only species which accepted the non-mimetic dummy egg at a higher rate later on during the incubation period than during earlier stages. A positive correlation was found between the power of egg discrimination and the rate of aggression shown towards the dummy cuckoo. Such aggression was stronger when both parents were present at the nest than when only one parent was present. The results of this study lend support to the hypothesis that the differences in the degree of responses by the host species towards parasitism by the cuckoo reflect different stages in a continuous coevolutionary arms race with cuckoos.

Variation in Schooling and Aggression Amongst Guppy (Poecilia Reticulata) Populations in Trinidad

Abstract: Schooling behaviour is an effective defence against predation but, since it depends on coordinated behaviour, it may restrict individual competition for limited resources. We tested the hypothesis that levels of individual aggression will be reduced in fish with a high schooling tendency by comparing the behaviour of guppies, Poecilia reticulata, from eight Trinidad populations. Schooling tendency was assayed in the wild. Fish were then transferred to the laboratory where aggression was measured when groups of eight males foraged on a small, but profitable, food patch. An inverse relationship between schooling tendency and intensity of aggression emerged. Guppies from populations without fish predators displayed a wide range of aggressive behaviours including active patch defence by the most dominant individual. Conversely, populations experiencing high predation, and with well-developed schooling behaviour, showed little aggression. Female guppies (three population tested) also varied in level of aggression and aggression was present in laboratory-bred as well as wild-caught fish. Individual aggression increased with group size but was independent of tank size. These results point towards a trade-off between antipredator behaviour and resource defence and confirm that schooling has associated costs as well as benefits.

Male song as a cue for mate choice in the European starling

Abstract: This study had two aims. First, we looked at individual differences in song characteristics between males of the European starling, and we related song behaviour to factors such as male age, pairing date, polygyny and male breeding success. Second, we experimentally tested whether song has an effect on female mating decisions. 1. During the breeding season, male starlings sing a very long and complex song consisting of a rapid succession of large number of different song types. We observed marked differences between males in average song bout length (a song bout was defined as a period of at least five seconds of song containing no pauses larger than 1.5 seconds) and in song repertoire size. Average song bout lengths ranged from 16 to 35 seconds. The individual repertoire size ranged from 23 to 67 song types. Repertoire size and average song bout length were positively correlated. 2. Both in the field and in captivity, yearling males sang shorter average song bout lengths and had smaller repertoire sizes than older males. 3. Males singing longer average song bouts and having larger repertoire sizes attracted females for pairing before their rivals with shorter average song bouts and smaller repertoire sizes.

Sexual Behavior of Male Northern Elephant Seals: I. Lethal Injuries To Adult Females

Abstract: [Adult female mortality of northern elephant seals, Mirounga angustirostris, was monitored daily throughout the breeding season and weekly during the non-breeding season at Ano Nuevo, California, during the period 1968 to 1987 Behavioral observation and necropsy findings were collected and circumstantial evidence was compiled to determine the cause of death Female deaths on the rookery were rare; only 17 female deaths were recorded over the 20 year period Cause of death could not be estimated in three cases because of advanced decomposition, one female died from an accident, and two others had no apparent trauma The majority of deaths (11) were caused by traumatic injuries inflicted by males during mating attempts as the females departed harems for the sea at the end of lactation Mortalities caused by males were distributed across a broad age range Based on the observed incidence of female mortality in relation to females present on the rookery, the probability of a female being killed by a male during the breeding season is about one in a thousand Females are expected to evolve adaptations to reduce injurious encounters with males Females are injured and killed by males during mating attempts in a variety of species A hypothesis concerning the conditions under which female animals sustain potentially lethal injuries during mating is advanced, Adult female mortality of northern elephant seals, Mirounga angustirostris, was monitored daily throughout the breeding season and weekly during the non-breeding season at Ano Nuevo, California, during the period 1968 to 1987 Behavioral observation and necropsy findings were collected and circumstantial evidence was compiled to determine the cause of death Female deaths on the rookery were rare; only 17 female deaths were recorded over the 20 year period Cause of death could not be estimated in three cases because of advanced decomposition, one female died from an accident, and two others had no apparent trauma The majority of deaths (11) were caused by traumatic injuries inflicted by males during mating attempts as the females departed harems for the sea at the end of lactation Mortalities caused by males were distributed across a broad age range Based on the observed incidence of female mortality in relation to females present on the rookery, the probability of a female being killed by a male during the breeding season is about one in a thousand Females are expected to evolve adaptations to reduce injurious encounters with males Females are injured and killed by males during mating attempts in a variety of species A hypothesis concerning the conditions under which female animals sustain potentially lethal injuries during mating is advanced]

Reproductive Benefits and the Duration of Paternal Care in a Biparental Burying Beetle, Necrophorus Orbicollis

Abstract: A monogamous pair of burying beetles (Necrophorus spp.) prepares a vertebrate carcass as a food source for their young and then protects the carcass and young from aggressive congeners. It was estimated that N. orbicollis males received four times the reproductive benefit on large (27-33 g) as opposed to small carcasses (10-18 g) in the field. Large carcasses were more likely to be taken over by free-flying intruders than small carcasses and the presence of a male parent reduced the probability of such takeovers. A male also decreased the time that a large carcass was vulnerable to a takeover. The presence of a male did not affect the number of larvae produced in field or laboratory experiments or the size of larvae reared in the laboratory. Males provided a longer duration of care when on a large carcass, when larval development was slow, or when the female was removed experimentally. The number of larvae, the number of days spent on the carcass, the mass of the carcass remaining at the end of the trial, female size, male size, burial depth and prior reproduction were not found to have independent effects on the probability of fin-ding the male on the carcass. In addition, males that were allowed to provide care prior to being placed in the field did not show a subsequent decline in reproductive success as compared to males that did not provide prior care.

Patterns of Visually Observable Behaviour and Vocalizations in Groups of Female Sperm Whales

Abstract: [Hourly records of the visible activities and vocalizations of groups of female and immature sperm whales, Physeter macrocephalus, off the Galapagos Islands were used to investigate relationships between vocalizations and visible activities, and to examine patterns of behaviour. There were strong correlations between most recorded variables, and multivariate analysis showed the rates of performing visually observable activities and vocalizing to be largely represented by an axis which is termed Sociality. About three quarters of the time sperm whales engaged in relatively stereotyped foraging for food, diving regularly, moving steadily, appearing only briefly at the surface in small clusters, and making regularly spaced trains of 'usual' clicks. However, for periods which usually lasted either about one or about five hours, and often in the afternoon, the whales would aggregate at the surface, usually in large, slow-moving clusters, often making patterned series of clicks called 'codas'. There was considerable variation in the behaviour observed, and sounds heard, during these periods of Aggregation. The mean levels of Sociality did not vary significantly between years, with season or with a measure of feeding success. The results are consistent with the hypothesis that a primary function of these periods at the surface is the maintenance of social bonds, although other functions are not excluded., Hourly records of the visible activities and vocalizations of groups of female and immature sperm whales, Physeter macrocephalus, off the Galapagos Islands were used to investigate relationships between vocalizations and visible activities, and to examine patterns of behaviour. There were strong correlations between most recorded variables, and multivariate analysis showed the rates of performing visually observable activities and vocalizing to be largely represented by an axis which is termed Sociality. About three quarters of the time sperm whales engaged in relatively stereotyped foraging for food, diving regularly, moving steadily, appearing only briefly at the surface in small clusters, and making regularly spaced trains of 'usual' clicks. However, for periods which usually lasted either about one or about five hours, and often in the afternoon, the whales would aggregate at the surface, usually in large, slow-moving clusters, often making patterned series of clicks called 'codas'. There was considerable variation in the behaviour observed, and sounds heard, during these periods of Aggregation. The mean levels of Sociality did not vary significantly between years, with season or with a measure of feeding success. The results are consistent with the hypothesis that a primary function of these periods at the surface is the maintenance of social bonds, although other functions are not excluded.]

Song sharing in a group-living songbird, the australian magpie, gymnorhina tibicen. part iii. sex specificity and individual specificity of vocal parts in communal chorus and duet songs

Abstract: In this paper we continue our study of the role of song in the social behavior of a cooperatively living songbird, the Australian magpie, Gymnorhina tibicen (Cracticidae). In this species, all members of a cooperative group sing and fight together in defense of their territory. Communal chorus songs consist of loud carol syllables; each individual sings a particular vocal role. We sampled the song repertoires of 24 magpies in 12 territorial groups in Queensland, Australia, and of 12 magpies in 4 territorial groups in the Manawatu region of New Zealand. Our results include: 1. Description of duet and chorus song. Carol portions of song are usually preceded by an introductory warble segment. Carol syllables are diverse in physical structure. We grouped 204 distinct carol syllables into 11 general classes. 2. Between-sex differences in syllable repertoires. Some syllable classes were sex-specific, and a few were sung by magpies of both sexes. Female-specific syllables were more complex structurally than those of males. Females had significantly (p 0.5) in the average percentage of the repertoire shared between same-sex birds who were vs were not territorial neighbors at our Queensland study site. 4. Carol song repertoires. The number of duet song types in each group's repertoire varied widely from group to group. Females had significantly (p<0.05) larger song repertoires than their mates. 5. Carol development in young birds. A young magpie seemed to sing variants of the carol syllables of only one parent, perhaps the same-sex parent, and echoed the parent's carol syllables during communal choruses. 6. Geographic variation in carol syllables. Carol syllables of individuals at our New Zealand study site were also sex-specific, and could be grouped into general classes. No syllables were the same as those recorded from the Australian study birds. 7. Song context. We compared the amount of time magpie groups spent warbling, warble-caroling, and not singing, during five commonly occurring types of contexts. Warbles were most frequent in nonaggressive intragroup contexts. Warble-carols were most frequent in aggressive intergroup contexts. We discuss the function of song in social cohesion, and group and individual recognition ; evolution of duet song; singing behavior of females; and mechanisms of vocal learning.

Long ultrasonic calls in male rats following mating, defeat and aversive stimulation: Frequency modulation and bout structure.

Abstract: Ultrasonic calls by rats may represent affective expressions and serve communicative functions. The temporal patterning and frequency modulation of the long, 21-30 kHz ultrasonic calls were studied in 7 male rats. Following ejaculation, defeat and aversive stimulation large samples of consecutive long calls were recorded and analyzed off-line using a spectrum analyzer. The analysis was limited to long calls because other types of calls were relatively rare under the circumstances of this study and the emitter could be determined by a typical breathing pattern with reasonable certainty only for long calls. Log survivor analysis of the intervals between calls revealed that rats emit 95 % of long calls in bouts of less than 6 calls. Except for the higher bout rate after defeat, there were no significant differences between tests in call duration, percent time spent vocalizing, bout duration and intervals between bouts. However, there were significant differences between individuals across tests in call duration, number of calls per bout and bout rate. The pattern and capacity to breathe are likely important limiting factors for several temporal characteristics of rat ultrasounds, in particular maximal call duration and range of interval duration within a bout. Post-ejaculatory calls were often strongly modulated in frequency (i.e. pitch) in the medial and terminal segments. These segments of calls emitted after defeat or aversive stimulation were essentially monotonous. We propose that rats emit at least 2 types of long ultrasonic calls-one monotonous, the other modulated-each reflecting a different affective state of the animal. The modulated type may reflect a state of behavioral inhibition such as initiated by ejaculation whereas the monotonous type may reflect a state of intense fear induced by an actual physical threat in situations where escape is blocked. Both types may serve a "desist-contact" function.

Frequent Copulations and Mate Guarding as Alternative Paternity Guards in Birds: a Comparative Study

Abstract: Male birds use a number of paternity guards to increase their certainty of paternity. Mate guarding appears to be the primary paternity guard, whereas frequent intra-pair copulations are used when males for ecological reasons are unable to closely guard their mates (e.g. in colonially breeding species where one pair member continuously has to guard the nest site against conspecifics, and in species where males provide their mates with all food during the fertile period). We tested whether mate guarding and frequent copulations are alternative paternity guards in a comparative study of the copulation behaviour of 173 bird species with detailed information available. The data base was reduced to statistically independent observations by calculating contrasts (standardized linear differences) between different taxa for copulation frequency, presence of mate guarding, mating system and body mass. Contrasts in mate guarding were strongly negatively related to contrasts in copulation frequency suggesting that they are alternative strategies. Body mass was unrelated to both of the alternative paternity guards, as revealed by weak negative correlations between contrasts in body mass and contrasts in frequent copulations and mate guarding, respectively. Males of taxa with mating systems with the most extreme skew in mating success (i.e. highly polygynous taxa) were characterised by an absence of both the frequent copulation and the mate guarding paternity guards.

The Functions of Song in Male House Wrens (Troglodytes Aedon)

Abstract: To assess the functions of song in male house wrens (Troglodytes aedon), we examined the pattern of song output during different stages of the breeding cycle and behaviour patterns of focal males and conspecifics that were associated with song. We recorded 2093.5 bouts of song from 11 different males in 12 breeding cycles during 3 years. Most song sung prior to pairing is sung at a high volume and is given spontaneously (i.e. is apparently not produced in response to the behaviour of any conspecific). Production of high volume spontaneous song ceased immediately for at least 7 days when the male paired, but resumed immediately upon loss of the mate. Paired males sang high volume spontaneous song after mates began incubating, and almost always sang this song within 10 m of an unoccupied nest site. Several males attracted second mates to these nest sites and immediately ceased their output of high volume spontaneous song. These observations strongly suggest that high volume spontaneous song functions in mate attraction. Male house wrens do not appear to use song on a routine basis to communicate with neighbours or other males. However, they do appear to direct song at other males when territories are threatened. Song is sung at intruders in the territory and at neighbours just establishing a territory of their own. Most song sung after pairing appears to be directed towards mates. We suspect than males use song to inform mates that there is no immediate threat of predation, allowing mates to move quickly to and from nest sites. We discuss the role and benefits of descriptive, correlative studies in assessing song function.

Sexual behavior of male northern elephant seals: ii. female response to potentially injurious encounters

Abstract: [During mating attempts by males, female elaphant seals, Mirounga angustirostris, are sometimes injured or killed as they return to sea at the end of lactation. We tested two predictions from the general hypothesis that females behave in a way that reduces the possibility of injury or death from sexual encounters with males: 1) departing females attempt to avoid males, and 2) if males cannot be avoided, departing females exhibit sexually receptive behavior to males, and thereby reduce the threat of injury from aggressive mating attempts. Circumstances surrounding the departure of 336 females from harems on the Ano Nuevo rookery in central California were recorded over the course of nine breeding seasons from 1982-1990. Females did little to avoid encounters with males surrounding harems; they did not leave in greater numbers at night, in groups, or during disturbances on the harem periphery. They did, however, leave harems preferentially at high tide which reduced the distance to the water and shortened transist time. Most departing females did not resist the mating attempts of peripheral males but, rather, they were unusually receptive. Receptive females received fewer blows capable of producing injury than resisting females. We conclude that receptive behavior in this context "buys safe passage". It is an effective means of reducing male aggression and the probability of injury; a male has no need to restrain a receptive female with blows, and should the most dominant male in the area copulate with a departing female, he frequently escorts her to sea and defends her from other males., During mating attempts by males, female elaphant seals, Mirounga angustirostris, are sometimes injured or killed as they return to sea at the end of lactation. We tested two predictions from the general hypothesis that females behave in a way that reduces the possibility of injury or death from sexual encounters with males: 1) departing females attempt to avoid males, and 2) if males cannot be avoided, departing females exhibit sexually receptive behavior to males, and thereby reduce the threat of injury from aggressive mating attempts. Circumstances surrounding the departure of 336 females from harems on the Ano Nuevo rookery in central California were recorded over the course of nine breeding seasons from 1982-1990. Females did little to avoid encounters with males surrounding harems; they did not leave in greater numbers at night, in groups, or during disturbances on the harem periphery. They did, however, leave harems preferentially at high tide which reduced the distance to the water and shortened transist time. Most departing females did not resist the mating attempts of peripheral males but, rather, they were unusually receptive. Receptive females received fewer blows capable of producing injury than resisting females. We conclude that receptive behavior in this context "buys safe passage". It is an effective means of reducing male aggression and the probability of injury; a male has no need to restrain a receptive female with blows, and should the most dominant male in the area copulate with a departing female, he frequently escorts her to sea and defends her from other males.]

Mutual Reciprocity of Grooming in Female Japanese Macaques (Macaca Fuscata)

Abstract: Grooming interactions among female Japanese macaques (Macaca fuscata) were observed and compared between affiliated and unaffilitated non-related pairs, mother and adult female offspring paris, and mother and immature offspring pairs. Unaffiliated (rarely interacting) members of pairs were likely to approach and then groom the other, in contrast to affiliated (frequently interacting) pairs, who more often approached and then solicited grooming from the other. The return receipt of a benefit just given, in the form of reciprocation of grooming, was immediate in non-related pairs. The brief interval between the occurrence of reciprocation facilitated the estimation of receiving as much benefit as was given in the case of rare grooming. However, such was not the case for related pairs. Adult female offspring solicited grooming from mothers more than immature offspring. The findings are discussed with reference to previous theories about the evolution of altruistic behaviour.

Playback Studies of Affiliative Vocalizing in Captive Squirrel Monkeys: Familiarity as a Cue To Response

Abstract: 1. A captive social group of squirrel monkeys in an outdoor habitat was presented with recorded chuck calls obtained from conspecific neighbors, neighbors of another Saimiri species, conspecific strangers, and members of the target group itself. 2. Responses to playback of chucks from their own group members were indistinguishable (in frequency, type, and latency) from those made to spontaneously emitted chucks. 3. The most familiar chucks (own group playbacks) received affiliative (chuck) responses as frequently as did spontaneously emitted chucks. Chuck playbacks from neighbors (conspecific or not) and strangers got significantly fewer chuck responses. 4. Chuck playbacks from conspecific neighbors received responses indicating mild interest, those from neighbors of another species received agonistic vocal responses, and those from conspecific strangers received both mild interest and agonism. 5. Own group chucks with multiple repeating elements elicited a higher response rate than single element chucks. This effect did not obtain for playbacks from animals outside the target group. 6. Results suggest that playback techniques can be successful with close range affiliative vocalizations like the chuck and that familiarity, species identity, and acoustic structure are all important variables.

Allomaternal care by female wedge-capped capuchin monkeys : effects of age, rank and relatedness

Abstract: We examined patterns of infant care and the relative importance of female age, rank and relatedness to allomaternal care for a wild population of wedge-capped capuchin monkeys, Cebus olivaceus in Venezuela. Mothers interacted primarily with their own infants throughout the study. Infant age affected the timing and type of allomaternal interaction; investigation occurred primarily in the first 3 months of life, carrying was dominant during the second 3 months, and association occurred primarily in the third 3 months. The onset and level of allomaternal care assured a high level of infant care as maternal care was declining, suggesting that allomaternal care is an important component of infant survival. The relative importance of female age, rank and relatedness varied for different behaviour. Relatedness was the most consistently important effect. Sibling females participated in allomaternal care almost 4 times more often than other females and were especially active in carrying and associating with infants. Female rank was an important effect when the coefficient of relatedness was less than 0.5: high-ranking females participated in allomaternal care more than low-ranking females. Old juveniles and nulliparous adults interacted with infants more than young juveniles and parous adults, but the effect of female age was relatively unimportant. Allomaternal nursing may represent a form of reciprocal altruism. Allomaternal nursing supplemented maternal nursing and was unrelated to kinship or rank of female.

Complementary Methods and Convergent Evidence in the Study of Primate Social Cognition1)

Abstract: Studies of primate social cognition aim at a) documentation of social behaviors that appear to require an understanding in the animals of their own relationships and the relationships among others; an ability to anticipate behavioral effects; intentionality, and so on, and b) determination of the psychological mechanisms and mental abilities underlying this complex sociality. Thus far, the first area of investigation, which is largely descriptive, has reveived more attention than the second. The most parsimonious assumption concerning nonhuman primates is that if their behavior resembles human behavior the psychological and mental processes involved are probably similar too. This is not the same as uncritically accepting the existence of these processes; alternative hypotheses need to be formulated and tested. The present paper advocates research over a broad spectrum, with reliance on a variety of methods, and emphasis on covergent evidence. Because each method has its own strengths and weaknesses, the most convincing support for a particular explanation will involve data from a number of sources, both observational and experimental. Four research methods are discussed: Qualitative description. Sometimes referred to as "anecdotalism", this method seeks to document the animals' spontaneous solutions to unusual social problems, and exploitation of rare opportunities. This method provides a starting point for research if it suggests remarkable cognitive capacities. It is unsuitable, however, for a conclusive comparison of alternative explanations. Quantitative description. The first goal of systematic research is to delineate the range of tenable hypotheses about the phenomenon of interest, i.e. to establish the cognitively least demanding explanation that cannot be rejected as well as the most demanding explanation that seems reasonable given the species' general intelligence level. The second goal is to compare alternative explanations. The advantage of quantitative description is that it can be applied in natural or naturalistic settings; the disadvantage is that it lacks control over variables. Controlled observation. A pseudo-experimental procedure that aims at controlling certain variables. An observation following a particular event is compared with an observation unpreceded by the same event but matched to the first observation on a number of other dimensions. A disadvantage, compared to experimentation, is the dependency on spontaneous events. Experimentation. Manipulation of the animal's experience and available information is a powerful tool to select among alternative cognitive explanations. The disadvantage is that this procedure requires an unusual environment and human involvement, both of which may alter behavior. Experimental results are particularly convincing, therefore, if they agree with knowledge gained by means of observational techniques.

Evidence That Female Razorbills Control Extra-Pair Copulations

Abstract: Several lines of evidence from a study of razorbill mating strategies indicate that females determine whether extra-pair copulations result in insemination: a. Direct observation suggested that males could not overcome female resistance; b. Females allowed repeated EPC attempts from the same male when they could have departed; c. No EPC attempts of post-egg-laying females were successful, but many were successful before laying, suggesting that females permitted insemination only when they could benefit from it; d. Males sometimes ceased attempting EPCs with females who persistently demonstrated unwillingness to copulate; e. Female behaviour has raised the possibility that sperm may be expelled. Two additional lines of evidence are deduced from a comparison of razorbill data with published accounts of the closely related common guillemot Uria aalge, in which forced EPCs are reported to occur regularly; (f) Male guillemots guard their mates with much greater vigilance than male razorbills, and (g) Male guillemots attempt EPCs by disrupting within-pair copulations and trying to force the pair female, while male razorbills decline such opportunities. The ability of females to control EPCs is important because it enables them to pursue a mixed reproductive strategy without suffering the costs of unwanted inseminations.

Litter Composition Affects Parental Care, Offspring Growth and the Development of Aggressive Behaviour in Wild House Mice

Abstract: Male mice pups reared with female sibings only are known to develop into more aggressive adults than males reared with males only. The purpose of this study was to examine whether differences in experience of sibling competition and/or parental behaviour might underlie these differences in adult behaviour. The parental care and development of eight litters containing four male pups (MM litters) and eight litters containing one male and three females (MF litters) was compared. As expected, MF males developed into faster attackers than MM males. A variety of measures of sibling competitive and aggressive behaviour, both in the home cage and during tests of competition for food, failed to provide any evidence that experience of success in competitive encounters played a prominent role in the development of individual differences in subsequent aggressiveness. On the other hand, clear differences in parental behaviour and offspring growth were detected as a result of the experimental manipulation. Mothers of MF litters provided more maternal care and appeared to wean their offspring later than mothers of MM litters. Despite this, MF pups grew more slowly than MM pups, suggesting that their high levels of sucking behaviour reflected high milk demand, perhaps due to a low milk supply, rather than high milk intake. One interpretation is that mothers of litters with a female-biassed sex ratio (MF mothers) were in poorer condition than those with a male-biased sex ratio (MM mothers), and consequently provided less adequate nutrition for their pups. Undernutrition during early life is known to result in the development of more aggressive individuals, perhaps by increasing competition for nipples and thereby promoting a more active/competitive mode of behaviour in later life.

Differences in the Responses of Captive Female Canaries To Variation in Conspecific and Heterospecific Songs

Abstract: The song of male canaries (Serinus canaria) differs greatly from one strain to another (wild and different domesticated breeds) depending on breeders' attempt during selective breedings. Female canaries (common canary strain) previously treated with estradiol were tested for their sexual copulation solicitation display in response to heterospecific and conspecific song stimuli. Heterospecific songs, winter wren (Troglodytes troglodytes) and greenfinch (Chloris chloris), elicited significantly weak reactions from females, but most of the females did react to these heterospecific songs. Two conspecific songs, the females' own strain song and a Border song, elicited significantly strong reactions compared to Harzer roller. A wild canary song has an intermediate song potential between Border and Harzer roller. As a whole these results support the ideas that artificial selection may have relaxed the strength of reproductive isolation and sexual selection.

The Singing Behaviour of Yellow Warblers

Abstract: Yellow warblers (Dendroica petechia aestiva), like other wood-warblers (Parulinae), use different songs in different circumstances. Analysis of recordings of 28,697 songs from 17 wild male yellow warblers from 1983 to 1988 at Amherst, Massachusetts, U.S.A., showed a consistent pattern of singing behaviour. I found that each male yellow warbler has a repertoire of songs divided into a single Type I song and a group of Type II songs. The patterns of song use are standardized, but the song types used as Type I and Type II songs are not; some males' Type I songs were similar to others males' Type II songs. Type I songs are sung relatively slowly in long runs of the song during daylight, are used near females, and, as demonstrated by mate removal experiments, are used more by unmated than by mated males. Type II songs are used in a dawn song bout, are sung relatively rapidly with much switching among song types, and are used in interactions with other males. Type I songs seem to have higher frequencies of modal intensity, especially in the initial phrase, and to have a greater increase in amplitude at the start of the song than do Type II songs. There may be some minor variation in the ways individual males use Type I and Type II songs, but the overall pattern of use is similar among males. Types I and II songs seem to be male-female and male-male signals, respectively. Thus, female response to song may have selected for a relatively simple signal with a high frequency of modal intensity, while male response to song may have selected for a relatively complex, low frequency signal.

Stabilization of Sexual Preferences By Sexual Experience in Male Zebra Finches Taeniopygia Guttata Castanotis

Abstract: Male zebra finches, Taeniopygia guttata castanotis, were normally-raised by zebra finches or were cross-fostered to Bengalese finch, Lonchura striata, foster-parents until 40 days of age. Following isolation until day 100, half the birds in each group were housed with a zebra finch female for seven days, isolated for three days and then housed with a Bengalese finch female for seven days. The other birds were exposed to females in the reverse order. Subsequent double-choice tests showed that all the normally-raised birds preferred zebra finch females whereas the preferences of cross-fostered males depended on the order of exposure to the two females: those exposed first to a Bengalese finch female preferred Bengalese finch females whereas of those exposed first to a zebra finch female, some preferred zebra finches, some preferred Bengalese finches and some showed no marked preference for either female. In order to examine the question of why the latter group showed such marked individual variation in their sexual preferences, a further group of males were cross-fostered to Bengalese finches and exposed to a zebra finch female and then to a Bengalese finch female and their behaviours were observed from day 21 until day 40 and for the two, seven-day periods with the females. The results show that, when comparing brothers within clutches, the one that begs and is fed more by by its foster-parents develops a stronger preference for Bengalese finch females and that the more song phrases a male directs to the zebra finch female during the first seven-day period, the stronger the sexual preference for zebra finch females in the double-choice tests. Hence, our results confirm and extend those of IMMELMANN et al. (1991) and KRUIJT & MEEUWISSEN (1991) that sexual imprinting may be a two step process. As a first step, information about the parents is learnt during a sensitive period early in life. In a second step, this information has to be tested for its validity for the selection of a sexual partner during first courtship encounters. It is this second step where the previously stored information is stabilized in memory. Giving conflicting information during the first and the second step, one can show that interactions between the young male and its parents as well as with its first sexual partner influence the final preference it shows in subsequent double choice tests.

Parental Care, Sibling Relationships and the Development of Aggressive Behaviour in Two Lines of Wild House Mice

Abstract: Distinct behavioural strategies for dealing with environmental and social challenge are known to exist in the adults of a variety of mammalian species, but little is known about the developmental bases of these strategies. In an attempt to start to fill this gap in knowledge, the present study set out to describe and compare the development of males from two lines of wild house mice which are known to differ in their aggressive behaviour and response to challenging situations. Adult males from one line (Short Attack Latency = SAL line) are more aggressive, show less sensitivity to changes in their environment and behave in a more internally controlled, routine-like way, than do males from the other line (outbred = Control line). The parental care and development of eight litters of four male pups from each line was observed. Paternal care did not differ between the two lines, but SAL pups received higher levels of nursing and general maternal care than did Control pups, and they appeared to be weaned later. Despite these differences, SAL pups grew more slowly than Control pups, suggesting that their high levels of sucking behaviour were a reflection of high milk demand, perhaps due to a low milk supply, rather than high milk intake. SAL pups were also delayed in a number of measures of early behavioural development relative to Control pups. The apparent early retardation in certain measures of SAL pup behavioural development disappeared at the end of the parental care period. From day 32 onwards, SAL pups began to show higher levels of aggression towards each other than did Control pups, and also showed a reduced reactivity to tests involving changes to the home cage environment ; a characteristic of adult SAL males. As expected, SAL males developed into faster attackers than Control males and, in SAL litters, intra-litter variation in attack speed was strongly influenced by preceding experience of sibling aggression. The fastest attackers in each litter were more successful in fights occurring in their litter than their slowest attacking siblings. No such relationship was observed in the Control litters where levels of inter-sibling aggression were low. The results point to the potential significance of maternal care behaviour and pup fighting behaviour in the development of the fast-attacking phenotype. One hypothesis is that inadequate nutrition of young SAL pups, mediated through the mother, promotes increased competition for access to the mother's nipples and predisposes the pups to develop into more active/competitive individuals. Subsequent sibling-sibling aggression appears to influence intra-litter variation in adult attack latency.

Response of Male Indigo and Lazuli Buntings and Their Hybrids To Song Playback in Allopatric and Sympatric Populations

Abstract: The hybridizing semispecies indigo and lazuli buntings (Passerina cyanea, P. amoena) were studied in song playback experiments in allopatric and sympatric populations. In allopatry, males of both species responded strongly to conspecific and weakly to heterospecific songs. In sympatry, indigo, lazuli and hybrid males reacted equally and strongly to both indigo and lazuli songs. Alteration of song structures, by presenting indigo syllables in lazuli temporal pattern and lazuli syllables in indigo temporal pattern, showed that the response of allopatric indigo and lazuli males was determined primarily by syllabic (phonological) cues in the test songs and not by the temporal pattern. The overall pattern of male response in sympatry and allopatry provides some understanding of the observed degree of reproductive isolation between these species.

Morphotype Related Dominance Hierarchies in Males of Macrobrachium Rosenbergii (Crustacea, Palaemonidae)

Abstract: Agonistic interactions in groups of Macrobrachium rosenbergii males were investigated in the laboratory. Each of the ten replicate groups consisted of the three distinct male morphotypes of this species: two Blue Clawed (BC) males and two Orange Clawed (OC) males matched to size, and two, much smaller, Small Males (SM). Male prawns formed a linear dominance hierarchy in which BC males were dominant over OC males which, in turn, were dominant over SM. Stabilization of the hierarchy over a period of three days was evident from reduction in the number of agonistic interactions and their intensity with time. The three male morphotypes differed in the extent to which they were involved in agonistic interactions and the nature of these interactions.

Male dominance and copulation disruption do not explain variance in male mating success on sharp-tailed grouse (Tympanuchus phasianellus) leks

Abstract: This study tested two hypotheses: that male-male competition and dominance relationships among males, rather than female choice of mates, principally determined the extreme variance in male mating success at sharp-tailed grouse leks; and, that male-male competition and dominance relationships among males principally determined the structure of the lek mating system as suggested by the recent "hotshot" model of lek organization (BEEHLER & FOSTER, 1988). Not all males in the study population obtained lek territories and more of those males that did were adults and had longer tarsometatarses than non-lekking males, which only visited leks and displayed elsewhere. There were no differeces between lekking and non-lekking males in mean body mass, wing length, and supraorbital comb size however. Dominant males, where dominance was measured by differences in the frequency that males were disrupted during courtship of females by neighbours, were not the most successful at obtaining copulations at leks. This is the strongest evidence that we have against the complete applicability of the hotshot model to our population of sharp-tailed grouse. Dominance status could not be predicted on the basis of body size, comb size, or age class. Dominant males were not the owners of the most centrally-located territories, nor were the territories of the most successful males at obtaining copulations taken over by more dominant males after successful males were removed from their territories. These results too provide evidence against the applicability of the hotshot model to our population of sharp-tailed grouse. Copulation disruptions by neighbouring males were common at leks. Copulations were more likely to be unsuccessful when they were disrupted than otherwise and remating by individual females occurred more often after they were disrupted than otherwise. However, based on limited sample sizes, females were apparently no more likely to remate with the disrupting male than with any other and copulation disruptions only redistributed copulations among an already successful number of males. Only 26% of the variance in male mating success could be explained in a multiple regression by any two- or three-variable combination of male traits and this was explained by variance in male size and number of yellow leg-bands. Male mating success and male size were inversely correlated in individual tests of significance; on average, smaller males apparently obtained more matings. The more centrally-located males apparently obtained more matings, but territory location was not correlated with any other variable except (perhaps) survival. There was a tendency for surviving males to change from more exterior to more interior locations in successive years, apparently as a result of new males settling around them rather than as a result of direct competition for interior spots. Male removal experiments were performed in which the most successful males were removed on each of number of leks. Contrary to predictions of the hotshot model (BEEHLER & FOSTER, 1988), male recruitment to these leks and the numbers of females visiting and mating at these leks the following year did not decline, and there was no increase in the frequency of disrupted copulations in the year following male removal. Consistent with the hotshot model, however, the variance in male success apparently declined at two of three leks in the year following male removal.

Alternative mating strategies and reproductive success in fallow deer

Abstract: Male fallow deer Dama dama, in a free-ranging population in the New Forest, southern England, either defend territories on a lek, defend single territories or are non-territorial. Mating success is highest on the lek, but unsuccessful lek males get fewer matings than some single territory males off the lek. The mating success of non-territorial behaviour, which is adopted by most males at some time during the rut, is uncertain. Non-lek matings in this population are higher than those reported in other lekking ungulate populations. Male fallow deer are not specialists; individuals commonly change strategies as mating opportunities dictate.

Social Inertia and Hormonal Control of Aggression and Dominance in White-Throated Sparrows

Abstract: To investigate the effects of familiarity with opponents on the activation of aggression and dominance by testosterone (T) in white-throated sparrows Zonotrichia albicollis, we studied birds in groups of five or six in outdoor aviaries and in a free-living population. Experiments were conducted between January and April, when plasma levels of endogenous gonadal hormones were low. Previously published experiments (ARCHAWARANON & WILEY, 1988) showed that when subjects were given subcutaneous implants of T, held individually in cages for one week, and then grouped with unfamiliar opponents, they established dominance over controls with empty implants. In contracts, the present study showed that low-ranking birds given subcutaneous implants of T and returned to their original groups and aviaries did not change in dominance rank nor in aggression scores over a period of two weeks. When these birds were regrouped with unfamiliar opponents in new aviaries, their dominance ranks and aggression scores increased. This rise in dominance rankings and aggression scores did not result from any effects of regrouping in the absence of hormonal treatments. The sexes did not differ in their responses to these treatments. In the field, T implants markedly increased some individuals' frequencies of aggression but had little or no effect on dominance relationships. The absence of behavioral changes in stable groupings after hormonal treatment, called social inertia, indicates that birds recognize the relative dominance of previous opponents, at least when encountered in familiar locations. Results from the field experiment thus suggest that white-throated sparrows can recognize at least 20 opponents. Hormonal state has more influence on dominance relationships of strangers than on those of opponents familiar with each other in familiar locations.

Mate Choice in Aidablennius Sphynx (Teleostei, Blenniidae); Females Prefer Nests Containing More Eggs

Abstract: Criteria for female mate choice were investigated in a natural population of a Mediterranean blenny, Aidablennius sphynx. Removable test tubes in concrete blocks were offered as nests. Each tube was guarded by a male and females laid eggs in the tubes. Nests with larger broods received significantly more spawning females. The numbers of eggs laid increased with brood size from empty nests to intermediate brood sizes, but this tendency is reversed if nests contain very large broods. Nests with and without broods were exchanged experimentally among males. The number of eggs a male received, after an empty tube was replaced by a tube with eggs, was significantly higher. Conversely, the number of eggs received after a tube with eggs was replaced by an empty tube, was significantly lower. Male display did not increase the probability that females spawned. Male size did not correlate with the numbers of eggs received. It is discussed that female preference for large broods might be adaptive because the number of eggs present in the nest is probably a reliable predictor of the survival chances of the eggs.

Auditory learning and filial imprinting in the chick

Abstract: The present study investigated auditory learning in chicks (Gallus gallus domesticus) in a filial imprinting situation, using an experimental design employed frequently in laboratory studies of visual imprinting. In Experiment 1, chicks were trained by exposing them to one of two artificial sounds. The presence of a visual stimulus (a rotating red box) during training enhanced subsequent preferential approach to the training sound (Exp. 1a 1b), while prolonged training in the presence of the box led to a significant preference for the training sound over a novel sound (Exp. 1c). In Experiment 2, chicks were trained by exposing them to one of two maternal cluck-vocalizations. There was significant auditory learning in the absence of the red box, but training in the presence of the box resulted in a greater preference for the training call. These results show that chicks can develop a preference for an auditory stimulus as a result of exposure to it. The presence of a visual stimulus during training enhances auditory learning, possibly through associative learning or through increased arousal or attention.

The Agonistic Behaviour of the Three Male Morphotypes of the Freshwater Prawn Macrobrachium Rosenbergii (Crustacea, Palaemonidae)

Abstract: The agonistic behaviour of the freshwater prawn, Macrobrachium rosenbergii, was studied in the laboratory. One hour long contests were conducted between prawns matched to size in each of the three sexually mature male morphotypes of this species; Small Males, Orange Clawed males and Blue Clawed males. An agonistic ethogram was established, consisting of 18 different acts. These acts were classified into indicators of dominance or subordinance following the application of cluster analysis. Prawns contests consisted usually of 3 phases: pre-escalated fighting phase, escalated fighting phase and post-escalated fighting phase. Contest phases differed both in the frequency of several acts and in the distribution of acts between the eventual winner and loser. In addition, the relative orientation and elevation of the opponents changed across phases. The inter and intra-individual sequences of acts of the winner and loser during the escalated fight were studied. Despite the similarity found in the behaviour of the two opponents during the escalated fighting, the eventual winner could be predicted by the relative number and duration of nips or by the relative number of times in which Complete and Incomplete-Lifting (two major displays of fight) were performed simultaneously with the snapping of the claws. Differences found among morphotypes pointed out a tendency of shifting from interactions with physical contact towards ritualized interactions without physical contact. This was correlated with the morphotypic developmental pathway and the concomitant increase of claw size.