Showing papers in "Ethology in 2010"

On aims and methods of Ethology

Abstract: Zusammenfassung Ich habe in diesem Aufsatz kurz anzudeuten versucht, was meiner Ansicht nach das Wesentliche in Fragestellung und Methode der Ethologie ist und weshalb wir in Konrad Lorenz den Begrunder moderner Ethologie erblicken. Hierbei habe ich vielleicht das Arbeitsgebiet der Ethologie weiter gefast, als unter Ethologen gebrauchlich ist. Wenn man aber die vielartige Arbeit jener Forscher ubersieht, die sich Ethologen nennen, ist man zu dieser weiten Fassung geradezu gezwungen. Ich habe in meiner Darstellung weder Vollstandigkeit noch Gleichgewicht angestrebt und, um zur Fortfuhrung des Gesprachs anzuregen, ruhig meine Steckenpferde geritten, vor allem das Verhaltnis zwischen Ethologie und Physiologie, die Gefahr der Vernachlassigung der Frage der Arterhaltung, Fragen der Methodik der ontogenetischen Forschung, und Aufgaben und Methoden der Evolutionsforschung. Bei der Einschatzung des Anteils, den Lorenz an der Entwicklung der Ethologie genommen hat und noch nimmt, habe ich als seinen Hauptbeitrag den bezeichnet, das er uns gezeigt hat, wie man bewahrtes “biologisches Denken” folgerichtig auf Verhalten anwenden kann. Das er dabei an die Arbeit seiner Vorganger angeknupft hat, ist nicht mehr verwunderlich, als das jeder Vater selbst einen Vater hat. Insbesondere scheint mir das Wesentliche an Lorenz‘ Arbeit zu sein, das er klar gesehen hat, das Verhaltensweisen Teile von “Organen”, von Systemen der Arterhaltung sind; das ihre Verursachung genau so exakt untersucht werden kann wie die gleich welcher anderer Lebensvorgange, das ihr arterhaltender Wert ebenso systematisch und exakt aufweisbar ist wie ihre Verursachung, das Verhaltensontogenie in grundsatzlich gleicher Weise erforscht werden kann wie die Ontogenie der Form und das die Erforschung der Verhaltensevolution der Untersuchung der Strukturevolution parallel geht. Und obwohl Lorenz ein riesiges Tatsachenmaterial gesammelt hat, ist die Ethologie doch noch mehr durch seine Fragestellung und durch kuhne Hypothesen gefordert als durch eigene Nachprufung dieser Hypothesen. Ohne den Wert solcher Nachprufung zu unterschatzen — ohne die es naturlich keine Weiterentwicklung gabe — mochte ich doch behaupten, das die durch Nachprufung notwendig gewordenen Modifikationen neben der Leistung des ursprunglichen Ansatzes vergleichsweise unbedeutend sind. Nebenbei sei auch daran erinnert, das eine der vielen heilsamen Nachwirkungen der Lorenzschen Arbeit das wachsende Interesse ist, das die Humanpsychologie der Ethologie entgegenbringt - ein erster Ansatz einer Entwicklung, deren Tragweite wir noch kaum ubersehen konnen. Am Schlus noch eine Bemerkung zur Terminologie. Ich habe hier das Wort “Ethologie” auf einen Riesenkomplex von Wissenschaften angewandt, von denen manche, wie Psychologie und Physiologie, schon langst anerkannte Namen tragen. Das heist naturlich nicht, das ich den Namen Ethologie fur dieses ganze Gebiet vorschlagen will; das ware geschichtlich einfach falsch, weil das Wort historisch nur die Arbeit einer kleinen Gruppe von Zoologen kennzeichnet. Der Name ist naturlich gleichgultig; worauf es mir vor allem ankommt, ist darzutun, das wir das Zusammenwachsen vieler Einzeldisziplinen zu einer vielumfassenden Wissenschaft erleben, fur die es nur einen richtigen Namen gibt: “Verhaltensbiologie”. Selbstverstandlich ist diese synthetische Entwicklung nicht die Arbeit eines Mannes oder gar die der Ethologen. Sie ist die Folge einer allgemeinen Neigung, Brucken zwischen verwandten Wissenschaften zu schlagen, einer Neigung, die sich in vielen Disziplinen entwickelt hat. Unter den Zoologen ist es Lorenz, der hierzu am meisten beigetragen und zudem manche Nachbardisziplinen starker beeinflust hat als irgendein anderer. Ich bin sogar davon uberzeugt, das diese Einwirkungen auf Nachbarwissenschaften noch lange anhalten werden und das die Verhaltensbiologie erst am Anfang ihrer Ontogenie steht.

Die angeborenen Formen möglicher Erfahrung.

Abstract: Zusammenfassung Die vorliegende Abhandlung entspringt dem Aufgabenkreis einer jungen Arbeitsgemeinschaft zwischen Geisteswissenschaft und vergleichender Psychologie, die das wichtigste Programm des neugegrundeten Philosophischen Institutes der Albertus-Universitat in Konigsberg darstellt. Sie ist aus der einen Abteilung dieser Anstalt, dem Institut fur vergleichende Psychologie hervorgegangen. Obwohl sie eine ganze Reihe unveroffentlichter neuer Beobachtungen und Versuche enthalt, stehen diese nicht genug im Mittelpunkte der Untersuchung, um eine Zusammenfassung von Ergebnissen in jener Form moglich zu machen, wie sie sonst in der induktiven Naturforschung ublich ist. Immerhin aber herrscht die induktive Denkweise in der vorliegenden Arbeit so stark vor, das eine kurze Zusammenfassung angebracht erscbeint, wenn sie auch notgedrungen die Form einer kurzen Inhaltsangabe annehmea mus.

Circadian rhythms: influences of internal and external factors on the period measured in constant conditions.

Abstract: The article reviews most of the data available on the period ẗ of freerunning circadian rhythms, measured in constant conditions. Emphasis is placed on the effects of light intensity and ambient temperature on ẗ, with references to influences of other external as well as internal factors. In the introduction, examples are given of spontaneous and induced variations in ẗ and its dependence on the experimental history. The discussion concentrates' largely on results obtained from arthropods and vertebrates.

Essay on Contemporary Issues in Ethology: Variation among Mammalian Alarm Call Systems and the Problem of Meaning in Animal Signals

Abstract: Understanding the information conveyed by animal signals requires studies of both production and perception. It is important to determine the relationship between signal morphology and the circumstances of production, the way signaller behavior varies with motivational state and the role of context in mediating responses to signals. Alarm calls are well-suited to research of this type because they are widespread in birds and mammals and typically evoke unambiguous responses. We review studies of alarm calling in primates and ground-dwelling sciurid rodents, concentrating especially on whether these signal systems may be viewed as ‘functionally referential’, that is, as conveying sufficient information about an event for receivers to select appropriate responses. Comparisons of the physical, behavioral and habitat characteristics of these species suggest that incompatibility of the escape responses required to avoid different classes of predators may have been an important factor in the evolution of functionally referential alarm calls.

Alternative Male Spawning Tactics and Acoustic Signals in the Plainfin Midshipman Fish Porichthys notatus Girard (Teleostei, Batrachoididae)

Abstract: The plainfin midshipman Porichthys notatus has two male reproductive morphs, ‘Type I’ and ‘Type II’, which are distinguishable by their physical traits alone. Type I males are eight times larger in body mass than Type II males and have a six-fold larger relative sonic (vocal) muscle mass than Type II males. In contrast, the testicles of Type II males are seven times larger than those of Type I males. This study demonstrates morph-specific patterns of reproduction, including acoustic signals, for Type I and II males. Field censuses of nests showed that only Type 1 males maintained nests. Type II males and females transiently appeared in these nests in association with each other. Infra-red video and hydrophone recordings in aquaria showed that Type I males maintained nests and readily vocalized. Long-duration ‘hums’ and sequences of short-duration ‘grunts’ were produced during advertisement and agonistic contexts, respectively. Humming Type I males attracted females to their nests, pair-spawned, and then guarded egg clutches alone. By contrast, Type II males neither acoustically courted females nor maintained available nest sites, but rather ‘sneak-’ or ‘satellite-spawned’ at the nests of Type I males. Type II males infrequently produced low amplitude, short duration grunts that were similar in spectral, temporal and amplitude characteristics to the grunts of females. Type II males appear to be obligate sexual parasites of the nest-building, mate-calling, and egg-guarding Type I males. The dimorphic body and vocal muscle traits of the two male morphs in the plainfin midshipman are thus paralleled by a divergence in their reproductive tactics and the properties of their acoustic signals.

Replicator selection and the extended phenotype.

Abstract: Adaptations are often spoken of as ‘for the good of’ some entity, but what is that entity? Groups and species are now rightly unfashionable, so what are we left with? The prevailing answer is Darwin's: ‘the individual’. Individuals clearly do not maximise their own survival so the concept of fitness had to be invented. If fitness is correctly defined in Hamilton's way as ‘inclusive fitness’ it ceases to matter whether we speak of individuals maximising their inclusive fitness or of genes maximising their survival. The two formulations are mutually inter-translatable. Yet some serious mistranslations are quoted from the literature, which have led their authors into actual biological error. The present paper blames the prevailing concentration on the individual for these errors, and advocates a reversion to the replicator as the proper focus of evolutionary attention. A gene is an obvious replicator, but there are others, and the general properties of replicators are discussed. Defenders of the individual as the unit of selection often point to the unity and integration of the genome as expressed phenotypically. This paper ends by attacking even this assumption, not by a reductionist fragmentation of the phenotype, but, on the contrary, by extending it to include more than one individual. Replicators survive by virtue of their effects on the world, and these effects are not restricted to one individual body but constitute a wider ‘extended phenotype’.

Using Principal Components and Factor Analysis in Animal Behaviour Research: Caveats and Guidelines

Abstract: Principal component (PCA) and factor analysis (FA) are widely used in animal behaviour research. However, many authors automatically follow questionable practices implemented by default in general-purpose statistical software. Worse still, the results of such analyses in research reports typically omit many crucial details which may hamper their evaluation. This article provides simple non-technical guidelines for PCA and FA. A standard for reporting the results of these analyses is suggested. Studies using PCA and FA must report: (1) whether the correlation or covariance matrix was used; (2) sample size, preferably as a footnote to the table of factor loadings; (3) indices of sampling adequacy; (4) how the number of factors was assessed; (5) communalities when sample size is small; (6) details of factor rotation; (7) if factor scores are computed, present determinacy indices; (8) preferably they should publish the original correlation matrix.

The adaptive significance of avian mobbing: II. Cultural transmission of enemy recognition in blackbirds: Effectiveness and some constraints.

Abstract: The “Cultural Transmission Hypothesis” and the “Alerting Others Hypothesis” of enemy recognition in birds was examined in mobbing experiments with captive blackbirds. Observer birds learned to mob a novel non-raptorial bird more strongly as a consequence of witnessing another bird mob strongly at the site of presentation. Strength of the observer's enhanced response was comparable to that elicited by a genuine predator. Under identical conditions, observers were also tutored to mob an unnatural, similar-sized object more strongly than initially but less intensely than to the novel bird after conditioning. Habituation to the novel bird did not impair subsequent conditioning. Cultural Transmission was effective along a “chain” of at least six birds. The phenomenon is discussed in terms of selfish benefits, kin selection and blackbird dispersal.

Behavior patterns and communication in feral horses

Abstract: The social behavior of feral horses was studied in the western United States. Stable harem groups with a dominant stallion and bachelor hermaphrodite hermaphrodite groups occupied overlapping home ranges. Groups spacing, but not territoriality, was expressed. Harem group, stability resulted from strong dominance by dominant stallions, and fidelity of group members. Eliminations of group members were usually marked by urine of the dominant stallion. Hermaphrodite-hermaphrodite aggression involved spacing between harems and dominance in bachelor groups. Marking with feces was important in hermaphrodite-hermaphrodite interactions. Foaling occurred in May and early June, following the post-partum estrous. All breeding was done by harem stallions. Young were commonly nursed through yearling age. These horses showed social organizations similar to other feral horses and plains zebras.

The Pooling Fallacy: Problems Arising when Individuals Contribute More than One Observation to the Data Set

Abstract: and Summary In ethological studies it is common practice to obtain multiple observations on each individual in a sample and to Pool these observations into one data set for statistical analysis. In this paper we argue that this procedure reflects a fundamental error in the logic underlying random sampling since it implicitly assumes that the purpose of data gathering in ethology is to obtain large “samples of behaviour” rather than samples of behaviour from a large number of individuals. That is, it is assumed that the reliability of estimates of population parameters can be increased by obtaining additional observations on individuals already in the sample rather than by increasing the number of individuals observed. Using a Monte Carlo simulation we show that when such Pooled data sets are analysed statistically, the probability of rejecting a true null hypothesis is almost always substantially greater than the stated alpha level. Zusammenfassung In ethologischen Untersuchungen ist es ublich, von jedem Individuum einer Stichprobe mehrere Meswerte zu gewinnen und fur die statistische Analyse die Werte aller Individuen zu einer einzigen Stichprobe zu vereinigen („pooling”). Diesem Verfahren liegt, wie in der vorliegenden Arbeit gezeigt wird, ein fundamentaler Irrtum bezuglich der zufalligen Stichprobenauswahl zugrunde, da implizit davon ausgegangen wird, man musse grose Stichproben der Verhaltensweisen anstatt Stichproben des Verhaltens moglichst vieler Individuen sammeln. Damit wird angenommen, das Populationsparameter zuverlassiger geschatzt werden konnen, wenn man mehr Beobachtungen am bereits in der Stichprobe vertretenen Individuen macht als wenn man zusatzliche Individuen beobachtet. Mit einer Monte–Carlo–Simulation wird gezeigt, das die statistische Analyse solcher zusammengesetzter („pooled”) Stichproben fast immer eine wesentlich grosere als die angegebene Irrtumswahrscheinlichkeit fur („type I error”) ergibt.

Acoustic Behaviour of Birds and Mammals in the Predator Context; I. Factors Affecting the Structure of Alarm Signals. II. The Functional Significance and Evolution of Alarm Signals

Abstract: and Summary I. 7 vocalizations emitted in the predator context are defined in terms of their function. The physical and physiological constraints on the evolution of the physical structure of alarm calls with respect to detectability and localizability are discussed. Detection of various calls depends on signal amplitude, environmental attenuation, signal-to-noise ratio, discrimination of the receiver against background noise, and absolute auditory sensitivity of the receiver. The combined effect of these factors is discussed for an exemplary predator-prey system, in which the hearing of both, predator and prey is known. Localizability of an alarm call is determined by its frequency, bandwidth, and possibly its amplitude relative to the auditory threshold of the receiver. Crude differentiation between localizable and non-localizable signals is not possible, and localizability of particular sounds varies between species. In some cases the question of detectability may render the problem of localizability unimportant. Besides detectability and localizability, other factors such as the acoustic background formed by the alarm calls of sympatric species and by the species' own repertoire of calls are discussed. II. Requisite conditions and available evidence for the evolution of alarm calls through individual selection and kin selection are described. Five types of alarm calls are discussed individually: 1The occurrence of mobbing calls indicates that a major function of these calls is predator deterrence (“move on”), although the calls also alert other prey and promote cultural transmission of the predator's characteristics. 2Alarm calls associated with evasive actions of the prey cause the predator to give up the hunt or diminish its hunting success by warning other prey, which only in some cases are closely related to the caller. 3Distress calls of a seized prey either attract other prey which then mob the predator, or attract other predators, which presumably attack the first predator. In both cases the chances to escape are enhanced because the predator's attention is diverted. 4Defence calls are used to threaten a predator. These calls often mimic sounds of other predators. 5Distraction calls may enhance the effect of distraction display. Although the different functions of various alarm calls are treated individually, certain of the calls may have more than one function and may be employed in nonpredator contexts as well.

Experimental Studies of Primate Vocalization: Specializations for Long-distance Propagation

Abstract: Acoustic features of tropical forests which may influence the form of primate vocalizations were investigated experimentally. Background noise levels and the source sound levels of primate vocalizations were measured in the Kibale Forest, Uganda. Attenuation of primate calls and pure tones was measured by broadcasting and rerecording these signals through the forest. Transmission of four primate species' calls were investigated; among the variables manipulated were functional class of vocalization (particularly long-distance vs. intragroup), height of broadcast, and time of broadcast. Zusammenfassung Bei vier Arten waldbewohnender Primaten wurden spezielle Laute gefunden, deren Aufbau und Zeitverlauf eine grosere Reichweite schafft als bei den Lauten, die der Verstandigung innerhalb der Gruppe dienen. In alien Fallen wurden akustische Muster gefunden, die die Dampfung vermindern. Die Lautintensitat weicht nicht immer von der normaler Laute ab. Sie ist jedoch bei Fernrufen konstanter, deren Dampfungsgrade weniger schwanken als bei Rufen innerhalb der Gruppe. Reichweiteversuche mit reinen Tonen lassen schliesen, das die spektrale Energieverteilung als Hauptursache fur die verminderte Dampfung in Frage kommt. Temporare Mittelfrequenz-„Fenster” und zuverlassig gute Ubertragung niedriger Frequenzen waren charakteristisch fur die Baumkronen-Zone. Die Ubertragung von Fernrufen wird ferner beeinflust von ihrem Zeitmuster und besonders von ihrem Auftreten zu Tageszeiten mit wenig Storgerauschen und geringer Dampfung. Insbesondere scheint die Temperatur wahrend der fruhen Morgenstunden zu minimaler Dampfung zu fuhren; in dieser Zeit treten die Fernrufe der Primaten charakteristischerweise besonders haufig auf.

Infanticide in Mountain Gorillas: New Cases and a Reconsideration of the Evidence

Abstract: Data on six cases of infanticide, one infanticide attempt, and one suspected infanticide in mountain gorillas (Gorilla gorilla beringei) are presented here for the first time. These and previously reported cases in the same population are analyzed in order to assess the circumstances and consequences of infanticide. Most infanticides occur when infants' mothers are not accompanied by their group's mature male (usually because he has died). Infants in this situation are almost certain to be killed by unfamiliar males unless they are nearly weaned. Active defense of infants by females is ineffective, and females cannot avoid unfamiliar males for prolonged periods. In contrast, infanticide is rare — yet has been observed — in encounters between mature males. It is not associated with group takeovers and male eviction by extra-group males, unlike the case in many other mammals. Demographic constraints and reproductive competition limit the occurrence of defensive coalitions between males. These factors, plus the high risks associated with male/male aggression, inhibit the occurrence of group takeovers by male coalitions. Infanticide shortens interbirth intervals and results in a high probability that a female will mate with the infanticidal male. These findings support the sexual-selection hypothesis for the evolution of infanticide and strongly support the argument that intersexual mutualism and intraspecific aggression have been central factors in gorillas' social evolution.

Large Scale Changes over 19 Years in Songs of Humpback Whales in Bermuda

Abstract: and Summary 163 songs of humpback whales (Megaptera novaeangliae) recorded near Bermuda during April and May of 13 years between 1957 and 1975 have been analysed as continuous sound spectrograms and compared. In each year's sample, all whales were singing basically the same song. However, the song was changing conspicuously and progressively with time so that songs separated by a number of years were very different in content. All the songs showed basic structural similarities so that it is possible to define a song form which characterizes songs from many years. We present some basic characteristics of the song form and consider the nature and extent of changes in content as a function of time. An analysis of the songs sung by groups of whales shows that normal singing continues even when whales are close enough, presumably, to hear each other. Such analysis demonstrates inter– and intra– individual variability, none of which is as great as the variation between songs of consecutive years. We do not understand the significance of changing songs. We know of no other non-human animal for which such dramatic non-reversing changes appear in the display pattern of an entire population as part of their normal behavior. Zusammenfassung In 13 Jahren (1957–1975) wurden bei Bermuda, jeweils von April bis Mai, 163 Gesange von Buckelwalen aufgenommen und analysiert. In jedem Jahr sangen alle Wale im Grunde denselben Gesang. Uber die Jahre anderten sich diese Gesange deutlich; Gesange, zwischen denen mehrere Jahre lagen, waren deutlich verschieden. Alle Gesange haben den gleichen Grundaufbau, an dem sich Anderungen uber die Zeit aufzeigen lassen. In Walgruppen treten Gesange auch dann auf, wenn die Tiere in Horweite voneinander sind. Intra– und interindividuelle Unterschiede waren kleiner als die Unterschiede zwischen aufeinanderfolgenden Jahren. Die Bedeutung der Gesangsanderung ist unbekannt. Von keinem anderen Tier ist solche Weiterentwicklung eines Signalverhaltens einer ganzen Population berichtet worden.

Evidence for Conceptual Quantitative Abilities in the African Grey Parrot: Labeling of Cardinal Sets

Abstract: An African grey parrot with experience in vocal labeling and categorization of objects, colors, and shapes has been taught to produce vocal numerical labels for collections of 2–6 objects. This ability generalized to sets of novel objects, to objects in random arrays, and to some heterogeneous collections. The results are discussed in terms of their relationship to numerical concepts in humans and other animals, particularly with respect to counting, language, and “prepared” associations.

Social Organization of African Wild Dogs (Lycaon pictus) on the Serengeti Plains, Tanzania 1967–19781

Abstract: African wild dogs were studied from 1967 to 1978 on the Serengeti Plains in northern Tanzania. The main objectives were to determine the status of the sub-population and to elucidate the ecology and behavior of this social carnivore. This paper describes the decline of the sub-population, the dynamics of pack composition, and patterns of dispersal.

Evolutionarily stable feeding strategy in sticklebacks

Abstract: When offered a choice between two simulated drift food patches 6 three-spined sticklebacks (Gasterosteus aculeutus L.) distributed themselves between the two patches in the ratio of patch profitabilities. This is an example of an “ideal free distribution” which could be achieved either if all fishes used the same pure strategy of feeding where reward rate is assessed to be highest, or if they adopted a mixture of that strategy and of random choice. Conditions for either possibility to be evolutionarily stable are discussed. Zusammenfassung 6 Dreistachlige Stichlinge (Gasterosteus aculeatus L.), die zusammen zwischen zwei nachgeahmten Driftfutterstellen wahlen konnten, verteilten sich auf die Stellen nach deren Ergiebigkeitsverhaltnis. Dieses Verhalten ist ein Bei-spiel fur eine s „ideal freie Verteilungrdquor;, die entweder dadurch erreicht werden konnte, das alle Fische dieselbe reine Strategic benutzen, namlich dort zu fressen, wo die Belohnungsrate am hochsten ist, oder aber dadurch, das die Fische eine Mischung aus jener Strategic und zufalliger Wahl benutzen. Bedin-gungen, unter denen jede der beiden Moglichkeiten evolutionsstabil ist, werden diskutiert.

Yawning as a stereotyped action pattern and releasing stimulus.

Abstract: Yawning was induced by instructing subjects to “think about yawning.” Yawns were consistent in duration (X = 5.9 s), periodic (X interyawn interval = 68.3 s), and within-subject stability in yawn duration and frequency was maintained for at least several weeks. These and other characteristics qualified yawning as a stereotyped action pattern. Although visually observed yawns were potent yawn releasing stimuli, “thinking about” or reading about yawning also elicited yawning and were additional vectors for its “infectiousness.” The respiratory, stretching and “imitative” aspects of yawning were also evaluated.

Bill Color Preferences of Zebra Finches

Abstract: Bill color varies with age and sex in zebra finches. Among birds of similar age and condition, males' bills tend to be redder and darker than those of females, but there is overlap in the phenotypic expression of the sexes. The bills of young birds are paler and less red than those of older birds. There is also interindividual variation within age and sex class. Experiments were performed to measure heterosexual and isosexual (= same sex) preferences of finches. Females preferred to associate with males with the reddest, brightest bills; they even preferred males whose bills were exaggerated through color applications of non-toxic marking pen. Males preferred to associate with females with bill colors in the middle of the phenotypic range. Females thus have “directional” preferences for male bill color, whereas male preference is “stabilizing” with regard to female bill color. In isosexual tests, neither sex showed a consistent preference for particular bill colors. Both sexes, however, displayed a tendency toward individual variability in preference. Bill color appears to be more important in heterosexual than in isosexual interactions. Several authors have recently suggested that organisms prefer brightly colored mates because bright coloration indicates superior physical condition. Results reported here do not support this hypothesis. Alternative functional explanations for the observed preferences are that bill color signals mating status, age or reproductive value. None of these appears to be a cogent explanation for the trends. Preferences do not appear to result from sexual imprinting. The possibility that the preferences are aesthetic and non-functional is discussed.

Group extinction and female transfer in wild chimpanzees in the Mahale National Park, Tanzania.

Abstract: and Summary A unit-group (K-group) of chimpanzees has shown a drastic demographic change in the course of 17 years (1966–1983) of field study. K-group had 6 adult males in 1966. Initially, the group lost adult males one by one between 1969–1975. The number of adult males in the unit-group was the main factor influencing the immigration of strange, cycling females and the emigration of cycling females, although nulliparous females born into K-group regularly emigrated to other unit-groups, regardless of the number of adult males within K-group. When the number of adult males in the group dropped to only two in early 1978, many cycling females began to associate with the males of a larger unit-group (M-group), as well as those of K-group. When K-group lost one of the remaining adult males and became essentially a “one-male” group in 1979, all the fertile, cycling females began to associate mostly with M-group and radically expanded their ranges, although their core areas tended to be closer to their original ranges. During this time the “alpha” male of K-group tried to restrict the ranging of “his” females to his normal range with a variety of herding techniques. The extent of the range expansions by immigrant females was influenced by their ages and ages of their youngest offspring. Parous females usually did not transfer or re-transfer permanently as long as their offspring were alive and the number of adult males within their group was more than three. Juvenile males occasionally followed their mothers and transferred between unit-groups. Some males refused to transfer even though their mothers transferred permanently. The destiny of these juvenile males who transferred is not clear, as such cases were rare. Annual ranges of immigrant females roughly coincided with those of the resident adult males of the unit-group. This observation effectively rejects the male-only community model of chimpanzee social organization (Wrangham 1979a). By the middle of 1983, K-group consisted of four animals: one lactating female with her infant daughter and one old post-reproductive female with her adolescent son. The loss of adult males was partly attributed to inter-unit-group aggression. Neighbouring unit-groups expanded their ranges at the expense of a small unit-group with few adult males. The large-scale transfer of cycling females to M-group is regarded as a female reproductive strategy, as such migration may lead to a greater number of available mates, and decrease the possibility of attacks from large neighbouring unit-groups, and moreover the females can still utilize their familiar feeding areas. Zusammenfassung Im Verlauf einer 17 Jahre dauernden Feldstudie durchlief eine bestimmte Schimpansengruppe (“K”) drastische demographische Veranderungen. 1966 enthielt sie 6 adulte Mannchen, verlor aber von 1969–1975 eins nach dem anderen davon. Als 1978 nur noch 2 adulte Mannchen da waren, schlossen sich viele der sexuell aktiven Weibchen abwechselnd diesen und den Mannchen der benachbarten groseren M-Gruppe an. 1979 war nur noch ein K-Mannchen ubrig, und alle sexuell aktiven Weibchen hielten sich meist bei den M-Mannchen auf. Dadurch erweiterten sie ihr Streifgebiet beachtlich, behielten aber das Heimatgebiet auserdem bei. Das letzte K-Mannchen versuchte mit verschiedenen Mitteln, “seine” Weibchen in seinem Gebiet zu halten. Die Zahl der erwachsenen Mannchen in einer Gruppe bestimmt vorrangig das Zuwandern fremder oder Abwandern eigener Weibchen. Nullipare in der K-Gruppe geborene Weibchen besuchten regelmasig andere Gruppen, unabhangig von der Zahl vorhandener Mannchen. Die Grose der Gebietserweiterung abwandernder Weibchen hing von ihrem Alter und vom Alter ihres jungsten Kindes ab. Mutter wanderten gewohnlich nicht dauerhaft ab, solange ihre Kinder lebten und es wenigstens 3 adulte Mannchen in ihrer Gruppe gab. Junge Mannchen folgten gelegentlich ihren Muttern zu einer anderen Gruppe, manche Mannchen aber blieben, auch wenn die Mutter ausgewandert war. Die zugewanderten Weibchen zogen im Jahr ungefahr dorthin mit, wohin die ansassigen Mannchen gingen. In der Mitte des Jahres 1983 bestand die K-Gruppe nur noch aus 4 Tieren: Einer saugenden Mutter mit ihrer Tochter und einer Greisin mit erwachsenem Sohn. Das Verschwinden der Mannchen ging zum Teil auf Zwischen-gruppen-Aggression zuruck. Benachbarte Gruppen dehnten ihren Wohnbereich aus auf Kosten kleiner Gruppen mit wenigen Mannchen. Das Uberlaufen so vieler Weibchen zur M-Gruppe wird als Fortpflanzungstaktik gedeutet: Die Zahl verfugbarer Paarungspartner wachst, die Gefahrdung durch Angriffe durch grose Nachbargruppen nimmt ab, aber dennoch konnen die Weibchen weiterhin die gewohnten Fresgebiete benutzen.

Forced copulations and intra-specific parasitism: Two costs of social living in the white-fronted bee-eater.

Abstract: White-fronted bee-eaters are colonially breeding birds that exhibit highly developed helping-at-the-nest. Through long-term studies of an individually-marked population, we have documented two costs of social living: 1) harassment of mated females by extra-pair males, and 2) intra-specific parasitism by females who lay eggs in the nests of others. Breeding females are sexually chased and, occasionally, forceably mated by males other than their mates. Focal-sampling of females throughout their period of receptivity revealed that the average female is involved in 5 to 8 sexual chases and is forceably copulated 0.15 to 0.23 times per breeding season. This risk to females would be much greater were it not for the behavior of male mates who remain close to, and actively defend, their partners. Such mate-guarding is highly effective — females entering and leaving the colony in consort with their mates are sexually harassed only 1/10 as often as females travelling alone. Although sexual harassment of females is common at bee-eater colonies, the risk of paternity uncertainty arising from forced copulations is thought to be low. The reason is that females copulate repeatedly with their male mates on all days immediately prior to as well as during egg laying. This point has been overlooked in previous reports and has led to an exaggeration of the paternity risks associated with forced sexual chases. We conclude that sexual chasing of extra-pair females is a low yield reproductive tactic employed primarily by monogamously mated males whose presence at the colony is required to allofeed and mateguard their own egg-laying females. Female white-fronted bee-eaters lay eggs in nests other than their own. This intraspecific parasitism constitutes a greater threat to certainty of parentage than does forced copulation. Over four years of study, 16% of nests were parasitized and 7 % of all eggs were laid by a female other than the breeder (Table 2). Parasitizing females come primarily from two sources: (1) members of mated pairs whose own breeding attempt is disrupted at the time of egg laying, and (2) single females who opportunistically add an egg at the nest of their parents (or parent plus step-parent). In each case of kin-parasitism, the “parasitic” female remained socially integrated with the host group and helped in the rearing of the young. In contrast, 9 of 10 females that parasitized the nests of non-relatives had no other interactions with the hosts (Table 3). Parasitizing females exhibited two specialized behaviors that enhanced their reproductive effectiveness: (1) they spent many hours observing, investigating, and testing the defenses of potential host nests, and (2) they preferentially laid in hosts' nests at the appropriate chronological stage of development. Breeding females also exhibited counterbehaviors against being parasitized. These included: (1) remaining sequestered in their nest chambers for 64%-65% of the daylight hours and 94 % of the pre-roost hours during their days of egg laying, (2) aggressively defending their nest entrances against all investigating (potentially parasitic) females, and (3) actively removing any eggs laid in their nests prior to the initiation of their own clutch. These tactics and countertactics suggest a long evolutionary history of parasitic opportunities and risks among white-fronted bee-eaters.

Phylogenetic Analysis of the Evolution of Display Behavior in the Neotropical Manakins (Aves: Pipridae)

Abstract: Phylogenetic systematic methods were applied in an investigation of the evolution of lek display behavior in the Neotropical manakins (Aves: Pipridae). Results of a previous investigation of the syringeal morphology of manakins were used as a behaviorally independent estimate of the phylogeny of the family. Three phylogenetic analyses of 44 display characters wer

The Complex Vocal Repertoire of the Adult Cotton‐top Tamarin (Saguinus oedipus oedipus)1)

Abstract: The cotton-top tamarin (Saguinus oedipus oedipus) has an extensive vocal repertoire which is derived from the variation of two basic elements and the sequential combination of those elements. A distinctive features analysis demonstrated at least 8 phonetic variants of a short, frequency modulated call (chirp) and five longer constant frequency calls (whistles). The call variants do not describe points on a single motivational continuum, but rather each variant represents a different message. A simple grammar is presented to describe all sequences of calls. While most of the call sequences fit the definition of phonetic syntax, at least two sequences appear to be exemplars of lexical syntax. Call structures are modified to provide increasing cues for auditory localization as animals are farther apart from each other. Comparisons of calls of S. o. oedipus with those of other callitrichids show a gradual divergence of call type with increasing geographic and phylogenic separation. Zusammenfassung Das Lautrepertoire des Lisztaffchens (Saguinus oedipus) wird beschrieben, einschlieslich der Situationen, in denen die Laute auftreten, und ihres vermuteten Bedeutungsinhalts. Das Repertoire beruht weitgehend auf zwei Grund-Elementen: kurzen frequenzmodulierten “Zirplauten” und langeren unmodulierten “Pfiffen”. Diese Elemente werden zu verschiedenen Varianten mit unterschiedlichen Funktionen umgewandelt. Sie konnen auch zu langeren Folgen (Phrasen) zusammengefugt werden. Dem liegt eine einfache Grammatik zugrunde. Meist haben die Elementfolgen einen anderen Bedeutungsgehalt als die Elemente, aus denen sie bestehen. Es gibt aber auch Folgen, die der Definition einer lexikalischen Syntax genugen, d. h. ihre Bedeutung ist zusammengesetzt aus der Bedeutung der Einzelelemente. Die akustische Struktur der Laute entspricht den von Morton (1977) fur Tierlaute aufgestellten Merkmalen akustischer Kommunikation. Das Lisztaffchen past die Lautstruktur der Entfernung vom Empfanger an. Je groser der Abstand zwischen den Tieren, desto mehr Orientierungshilfen enthalten die Laute. Die Laute sind weitgehend denen gleich, die fur verschiedene Unterarten von S. oedipus beschrieben wurden. Zu Nachbararten und Nachbargattungen wachsen die Unterschiede mit groserer geographischer und taxonomischer Entfernung.

Sexual Behavior, Sexual Interference and Sexual Defense in the Salamanders Ambystoma maculatum, Ambystoma tigrinum and Plethodon jordani

Abstract: Courtship behavior and ♂ - ♂ interactions in the salamanders Ambystoma maculatum, Ambystoma tigrinum and Plethodon jordani were investigated with the aim of determining their adaptive significance. The courtship behavior of approximately 30 pairs of A. maculatum, 10 pairs of A. tigrinum and 50 pairs of P. jordani was observed. Behaviors were recorded by verbal transcription, motion picture and still photography. A. maculatum ♂ ♂ court rapidly, deposit many spermatophores, have simple behavior and low success with each spermatophore. P. jordani ♂ ♂ court slowly, usually deposit a single spermatophore, have complex behavior and high success with each spermatophore. A. tigrinum is intermediate in these respects. ♂ ♂ of the two Ambystoma species actively cover the spermatophores of rival ♂ ♂. Male A. tigrinum and P. jordani dupe rival ♂ ♂ into unprofitable spermatophore depositions by mimicking female behavior. Male A. tigrinum actively transport the ♀ away from rivals. Male P. jordani chase rivals away from the ♀. A hypothesis is proposed which relates the evolution of courtship speed, spermatophore number and sexual defenses to the length of the courtship season, the probability of intrusion by rival ♂ ♂ and the sexual receptivity of the ♀. Zusammenfassung Drei Arten von Salamandern unterscheiden sich deutlich in der Lange der Zeit, die das ♂ vor einem ♀ balzt, ehe es die Spermatophore absetzt, und in der Zahl der Spermatophoren, die es pro Balz absetzt. Daraus lassen sich die folgenden Hypothesen zur Evolution der Salamanderbalz ableiten. Die Balzdauer pro Spermatophore scheint ein Kompromis zwischen dem Erfolg bei einem bestimmten ♀ und der Ausschaltung von Rivalen zu sein. Je langer die Balz ist, desto wahrscheinlicher findet das ♀ die Spermatophore. Also sollte das ♂ viel Zeit in jede Spermatophore investieren (z. B. Plethodon). Wenn aber Rivalen hinzukommen, konnten sie in dieser Zeit die Besamung stehlen. Deshalb balzen die polyandrische Ansammlungen bildenden Arten (z. B. Ambystoma maculatum) schnell und investieren wenig Zeit in jede Spermatophore. Die Zahl von Spermatophoren pro Balz scheint ein Kompromis zwischen dem Erfolg bei einem bestimmten ♀ und der Dauer der Balzzeit. Die ♂ ♂ haben nur einen beschrankten Vorrat von Spermatophoren. ♂ ♂, die in der Balz Spermatophoren sparen, konnten mehr ♀♀ begatten als ♂ ♂, die nicht sparsam sind. Das kann sogar den Nachteil eines geringeren Erfolgs pro ♀ wettmachen, wenn die Fortpflanzungszeit lang ist (z. B. Plethodon). Mannliche Salamander drangen sich in die Balz anderer ♂ ♂ hinein. Solche Storungen konnen einen Selektionsdruck auf Verteidigung des ♀, schnelle Balz, und auf Vergroserung der Zahl von Spermatophoren je Balz ausuben.

Quantitative Analysis of Animal Vocal Phonology: an Application to Swamp Sparrow Song

Abstract: Sound spectrograms have been a traditional method for comparing animal vocalizations and demonstrating their similarities or differences, but quantification of the comparative process has been difficult. This lack of quantification has hindered progress in documenting the timing and degree of song development in song birds. With this in mind, computer-based methods for sound comparison and sound averaging were developed. These methods utilize a numerical representation of a sound's frequency-time structure to compute a similarity value between any two sounds and an average sound spectrogram for a set of sounds. These analytical techniques were applied to an analysis of song notes of the swamp sparrow (Melospiza georgiana). The results demonstrate the usefulness of the methods and reveal new details in the description of the swamp sparrow's set of species-universal note types and in the decrease of note variability during the course of developmental transitions from subsong, through plastic song to song crystallization.

Relationship between Song Repertoire and Age in the Canary, Serinus canarius

Abstract: We recorded the song of six male canaries during their first and second year of life to see if we could detect systematic age-related changes. Soundspectrographic analysis revealed that many syllables from the previous year were omitted and many new ones were added. There was a significant increase in syllable repertoire during the second year. The proportion of single-element syllables increased between year 1 and year 2. These results indicate that neural pathways responsible for song learning in canaries remain plastic in adulthood. We suggest that the larger song repertoires of older ♂♂ confer a reproductive advantage by acting as a more potent stimulus on ♀♀.

Population Dynamics during a 15 Year Period in one Community of Free-living Chimpanzees in the Gombe National Park, Tanzania

Abstract: Zusammenfassung Schimpansen werden im Gombe-Nationalpark in Tansania seit 1960 beobachtet. Die Tiere bilden soziale Gruppen, die wir “Communities”, die Japaner “Unit-Groups” nennen. Als Faktoren, die von 1965 bis 1980 die Grose und Zusammensetzung der Hauptgruppe beeinflusten, werden erortert: Pubertatsalter, Fortpflanzungsreife, Fortpflanzungszyklen der Weibchen, Geburtenfolge, Wechsel von Individuen zwischen Gruppen, Geschlechterverhaltnis, Alterszusammensetzung und Mortalitat. Zwischen 1970 und 1972 teilte sich die Gruppe. In den folgenden 5 Jahren wurden die Mannchen und mindestens eins der Weibchen, die sich als Kahama-Gruppe abgespaltet hatten, von den Mannchen der groseren Kasakela-Gruppe umgebracht. Eingehend werden Mortalitatsfaktoren (Krankheiten, Verletzungen, Mutterverlust, Alter) sowie der allgemeine Gesundheitszustand besprochen. Die deutlich unterschiedenen Regen- und Trockenzeiten im Gombe beeinflussen die Gesundheit und wohl auch die Fortpflanzung. In der Gruppe gibt es Inzucht, aber der Wechsel von Weibchen in andere Gruppen (der noch einigermasen ratselhaft bleibt) sorgt fur genetische Auffrischung. Die Befunde werden mit der einzigen anderen Langzeitstudie an freilebenden Schimpansen aus den Mahali-Bergen in Tansania verglichen. Der Einflus kunstlicher Futterung in beiden Gebieten wird erortert.

The Adaptive Significance of a Complex Vocal Repertoire in a Neotropical Frog

Abstract: Male frogs, Physalaemus pustulosus, produce an advertisement call of varying complexity. Males increase call complexity in response to vocal competition from other males, and females are preferentially attracted to complex calls. The role of female choice and predation in the evolution of the advertisement call's complexity series is discussed. Zusammenfassung Mannchen von P. pustuloses haben einen Ruf, der verschieden kompliziert sein kann. Er besteht aus einem langgezogenen Laut und 0–6 Schnalzern. Einzeln rufende Mannchen ausern meist nur den langen Laut; horen sie andere Mannchen rufen, dann ausern sie auch die Schnalzlaute. Die Weibchen bevorzugen Rufe mit Schnalzern. Wir vermuten, das die Weibchen komplizierte Rufe bevorzugen, weil die Schnalzer Auskunft geben uber das Korpergewicht der Mannchen. Andererseits erhohen komplizierte Rufe fur die Mannchen das Risiko, von Raubfeinden gefast zu werden. Die variable Form des Rufes scheint also ein Kompromis zwischen maximaler Anlockung von Weibchen und minimaler Anlockung von Raubfeinden zu sein.