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Zur Brutbiologie Der Trottellumme (Uria Aalge Aalge Pont.)
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The behavioural relations of the Guillemot (Uria. aalge, Pont.) to its incubating site, eggs and chicks, the significance of these relations for organising the reproductive activities within the community, and the "jumping-off" of the chicks from the incubation site down to the seashore, are described. The significance of various factors was derived from observation of the natural reproductive behaviour and conclusions were then tested by experiments with individuals marked by colour-patches.
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Experience and Maturation in the Development of Sexual Behaviour in Male Puberty Rat
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The sexual activity of male rats which had not been engaged in heterosexual activity was compared with that of others having a certain amount of sexual experience. The development of the pattern of behaviour in the later group was followed from 105 days of age to 138. It was found that: 1. Continuous changes in the sexual behaviour occurred, the frequency of ejaculations per hour increased, the number of intromissions before ejaculation decreased, the duration of the series of copulations preceding an ejaculation was shortened and the post-ejaculatory latency was shortened. 2. Comparing experienced with non-experienced rats of the same age it became evident that learning intervened only determining the lengths of the post-ejaculatory latencies the other components being unaffected. It ís concluded that individual experience affects the length of the post-ejaculatory latency, other changes appearing in the pattern of behaviour with increasing age dependent on maturing processes in the biological organism.
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Sur Le Comportement De Lariophagus Distinguendus Först (Hym. Pteromalidae)
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Lariophagus distinguendus Först, est un Chalcidien parasite qui creuse un trou dans le cocon de Stegobium paniceum L. et dépose un oeuf sur l'hôte enfermé. Un travail précédent (KASCHEF, 1955) avec des populations de ce parasite, du Stegobium paniceum L. et du Ptinus tectus Boield. a montré que le parasite a un preferendum marqué pour le stade prénymphal de l'hôte enfermé dans son cocon. SMIRNOV et POLEJAEFF (1937) pensent que le son émis par la larve de Calandra granaria L., quand elle ronge les grains de blé, joue le principal rôle dans la recherche de l'hôte. Quoique nous soyons d'accord avec la description générale donnée par ces auteurs les présentes recherches ne confirment pas la plupart des détails. L'exactitude de leur proposition a été examinée en utilisant: (a) des élevages naturels du stade convenable de l'hôte, (b) des larves à terme de l'hôte tuées par le gaz carbonique, et (c) le cadre de Chtcherbakoff. Nous démontrons que: i - La capacité du Lariophagus distinguendus Först., à trouver son hôte est si grande que la femelle peut découvrir la présence de quelques grains infestés par Stegobium paniceum L. dans 96.000 grains sains. La femelle peut descendre parmi des grains sains à une profondeur de 50 cm quand les grains de blé infestés sont placés à différents niveaux; ainsi qu'à une profondeur de 30 cm quand un seul groupe de grains de blé infestés est placé au fond du récipient. 2 - La réponse de la femelle de Lariophagus aux larves à terme vivantes de St. paniceum L. extraites des grains de blé infestés est un peu moins ou à peu près égale à la réponse à des prénymphes enfermés dans leurs cocons. 3 - La femelle de L. distinguendus Först. est attirée vers l'hôte principalement par l'odeur. Aucun fait vraiment probant n'a été obtenu en ce qui concerne l'attraction par le son produit par les larves de l'hôte. La femelle du parasite préfère les prénymphes du Stegobium paniceum L. aux larves à terme, vivantes ou tuées par le gaz carbonique. 4 - La localisation de la source du stimulus semble être effectuée seulement par les antennes, dont les movements qui précèdent la localisation de l'hôte suggèrent qu'elles portent les organs sensoriels adèquats.
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The Activation of an Instinct Caused By a "Transitional Action"
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It is shown by examples that the performance of a part action which also forms part of another activity than that being performed may lead to activation of the instinct to which this other activity belongs. Thus a transition from one activity to another takes place through a transitional action, i.e. a part action which is common to the two activities. It is presumed that the activation of an instinct during a transitional action takes place in the following way: the instinct is previously activated under the threshold, but during the performance of the transitional action the proprioceptors registrate the performance of an action which belongs to this instinct even if it is not active. This causes a lowering of the threshold for the activating stimuli of the instinct which thereupon are able to activate the instinct. It is shown that the activation by a transitional action may be of importance for the interpretation of some behaviour patterns. Thus a displacement activity which is determined by an initial posture or movement (= transitional action) must be activated autochtonously. The combination of different activities (incl. escape reactions) in the complicated bathing behaviour of some Anatidae may be due to the effect of transitional actions, and the same may have determined the development of the ritualized neck-dipping and other activities in the pre-copulatory behaviour in Cygninae, Anserinae, and the Cararca group.
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A Study of the Behaviour of the Chacma Baboon, Papio Ursinus
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i. In this paper an attempt has been made to describe the behaviour of the Chacma, and to make an analysis thereof. The observations were made on two young captive baboons, Joe and Jenny, as well as on wild ones. ii. There is a hierarchical organisation of the troop which mainly shows itself in feeding and mating. Among the females the hierarchical order is less obvious than among the males. It seems as if females in oestrus are of higher rank than those in anoestrus. The male-female association is often very casual and the formation of permanent family groups are rather the exception than the rule. Idle males act as sentinels. iii. A. All sounds emitted express emotion. Various sounds and their emotional motivations are described. B. In the typical threat posture the animal stands facing the opponent with lifted head, stiff arms and hairs on shoulder and back raised. It looks straight at the opponent. Often it snarls and its movements are rigid and jerking. It may rub the ground with its hand or stamp with it. It then suddenly darts forward in attack. C. The opponent is pursued and, if caught up with, is bitten, usually in backhead and shoulder, or, if smaller rubbed against the ground. Other baboons come to the rescue of the defeated individual. In nature this leads to a wild chase. In captivity it may end up in some mass fighting. D. Baboons have great respect for authority. E. In the retreating submissive behaviour the animal crouches and moves with its side or tail towards the aggressor. The teeth may be bared in horror and the aggressor is watched evasively over the shoulder while the retreating animal presents its hindquarters. F. Yawning and scratching are commonly noticed in sentinels. They are considered as displacement activities, signifying nervous tension. G. When eating the baboons frequently rub their food against their fore-arm. It may signify nervous tension. H. Sexual behaviour has given rise to many other activities. a. Great interest is often shown in females in oestrus, the genitalia of whom are often examined by other females and juveniles. b. Mating is initiated by lipsmacking and presenting from the female. c. Masturbation and onanism is common in inferior males without a female. d. Inverse and homosexual behaviour is common in captivity. e. Presenting is a friendly and inviting gesture with a sexual origin. f. Lipsmacking is a very much used friendly and inviting gesture, probably with a sexual origin. I. Grooming is a typical female activity. It is impossible to explain its significance. The concentration with which the act is performed seems to indicate some physiological background. J. The various types of behaviour have been analysed and their elements and significance listed. K. In cases of opposing emotional motivations the elements of behaviour are combined in characteristic ways which are interpreted by the onlooking baboons. L. Female baboons are usually fond of very young individuals. The mothers usually look very well after their babies during their first few weeks, but the interest gradually fades after the young ones have been weaned and begin to stray about. They show great interest in each others' babies. The maternal instinct is developed already at an age of six months or less. The attitude of the male towards the young varies from complete intolerance to great affection. Two cases of males acting as mother substitute are described. M. The young individual always knows its guardian and seeks its protection in case of danger. N. In play, the young haboon includes almost all the activities of the adult. Fighting, biting and mating are some of the main features. The various types of bites are described. The play copulation includes the full ritual exhitited by adults during their mating. It is surprising to find that the innate ritual is fully developed in youngsters only a few months of age. O. Any object can be of value to a baboon. Its value depends on the interest shown in it by other individuals. P. Baboons are primarily vegetarians, but they love in addition to their diet of insects and probably birds' eggs. Occasionally they turn carnivorous. Q. Much food is dug up from the ground or collected under stones. The turning of stones is an innate behaviour which is performed at a very young age. R. Baboons seem to have an innate fear of snakes or other cylindrical bodies which can bend and wriggle. Towards other animals which do not serve as food they normally show indifference. On occasions however, the juveniles take pleasure in teasing other animals. Cases where kudu and lions were teased are described. In the latter case the mature males attempted to maintain order among the juveniles trying to prevent them from approaching too close. This action seems to indicate that the rescue responses can not be explained as a simple reflectory response.
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Prey Recognition in the Praying Mantis 1)
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The external factors which release and control prey capture in the praying mantis have been studied in Parastagmatoptera unipunctata and Hierodulae gen. In tests with various kinds of live prey and dummies the strike has been found to be most readily released if I.) the prey is within reach of the forelegs; 2.) the prey moves as a whole while exhibiting rapid, jerky movements of appendages. Size, shape and direction of the prey are less important, while color and odor have no strike releasing value. Continuous presentation of a strike-releaser results in more or less rapid response-waning, depending upon its releasing value. Suboptimal dummies cause complete refractoriness within minutes, while optimal prey continues to elicit strikes after several hours. However, even under optimal internal and external conditions the frequency of strike-discharge declines rapidly at first and then more slowly. By comparing mantids normally raised on live flies with isolated, hand-fed animals and with mantids which were exclusively fed on prey of low stimulus-value, it has been shown that 1.) the strike-releasing qualities of the prey are not learned through experience; 2.) the stimulus-response relations of the subsequent acts of catching and putting to the mouth can be quantitatively modified during the individual life.
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Die Spiele Von Mungo Und Ichneumon
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1. In Gefangenschaft gehaltene Mungos und Ichneumons zeigen häufig eine Spiel-stimmung, die durch Aufforderung eines Partners oder eines Gegenstandes (z.B. Ball) zum Mitspielen gekennzeichnet ist (Spielappetenz). Bei Beginn und während des Spiels wird häufig ein kurzer Hochsprung fast auf der Stelle vollführt, der als generelle Spiel-geste eine entspannte Stimmung anzeigt. 2. Die Herpestinen sind wegen ihres mit Neugierverhalten gemischten normalen Appetenzlaufens zur Nahrungsbeschaffung in besonderem Masse für vielgestaltige Spiele prädestiniert. Die meisten, aber nicht alle Teilhandlungen der Spiele sind Komponenten normaler Instinkthandlungen. 3. Renn-, Kampf, Flucht-, Versteck-, Beute- und Fortplanzungsspiele sowie einige kennzeichnende Experimentierspiele werden beschrieben. Das Einschlüpfen in engere Höhlen (auch in Taschen, Ärmel, Hosenbeine) oder das Entlanggleiten unter Decken, Teppichen usw. ist bei Mungos offenbar stark positiv gefühlsbetont und wird häufig spielerisch ausgeübt ("Maulwurfsspiel", "Schildkrötenspiel"). Bei Kampfspielen zeigen beide Arten als gemeinsame Komponenten: Aufrichten, pendelnde ("kokettierende") Kopfbewegungen, von oben auf den Partner Fallenlassen, Umklammern und Überraschungsangriffe aus einer Deckung heraus. Ein völliges Abkugeln und auf den Rücken Rollen in der Verteidigung ist nur für den Mungo kennzeichnend. Beim Spiel mit Beuteattrappen (Ball, Lappen) treten die gleichen Teilhandlungen auf wie beim Spiel mit echter Beute: Belauern, halbkreisförmiges Umlaufen, Aufrichten, pendelnde Kopfbewegungen, Anstossen, Zupacken usw. Experimentierspiele sind vor allem infolge des beteiligten Neugierverhaltens sehr vielgestaltig. Dabei werden z.T. ungewöhnliche Bewegungskoordinationen erfunden (Rollen oder Schaukeln im Papierkorb, Herumlaufen mit über den Kopf gestülpter Tüte oder mit auf dem Rücken liegenden Korbdeckel, Purzelbaumschlagen usw.). 4. Ein Übergang vom Spiel- zum Ernstverhalten ist normal beim Spiel mit echter Beute (Töten und Fressen als consummative action), ist häufig beim Spiel in engen Höhlen (Höhlenverteidigungsinstinkt), aber sehr selten beim Kampfspiel (nur bei extremer Erregungssteigerung). 5. Ein Vergleich mit den Spielen anderer Raubtiere lässt eine Verwandtschaft der Herpestinen mit den systematisch meist als fernstehend betrachteten Musteliden möglich erscheinen. 6. Mungos markieren auch beim Spiel hochstehende Gegenstände gelegentlich mit den nach Honig duftenden Wangendrüsen. 7. Eine starke Vergrösserung der Transversalfortsätze der Lumbalwirbel, die unter den Herpestinen nur die Mungos zeigen, ist wahrscheinlich im Zusammenhang mit dem Abkugeln phylogenetisch entwickelt worden, weil gerade diese besonders schützende Wirbelpartie dem Feinde zugewendet wird.
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Notes On the Behavior of Some North American Gulls. Iv. the Ontogeny of Hostile Behavior and Display Patterns
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This paper is primarily a description of the ontogenetic development of ritualized display patterns (specialized social signals) in young Franklin's Gulls (Larus pipixcan) and Ring-billed Gulls (L. delawarensis) during the period from hatching to fledging. All the display notes and calls of older birds seem to be derived from the Distress Notes of newly-hatched chicks. These original Distress Notes (which may be divided into high intensity and low intensity types) occur whenever a chick is uncomfortable or "frustrated" in any way. They are "designed" to make the parent remedy the situation which is causing the discomfort. The subsequent development of the original Distress Notes is essentially a process of elaboration and simultaneous "segregation" or "restriction". The two original types become more distinct morphologically; one of them breaks up into several new types; and each type becomes less and less "generalized", eventually becoming fixed or confined to a particular, single, "frustrating" conflict or ambivalent situation, in which two or more drives (attack, escape, and sometimes some other) are activated simultaneously. These calls and notes also acquire a hostile signal function, becoming threat or appeasement. Most of the display postures and movements develop by a process of what may be termed "ontogenetic ritualization". They first appear as flexible and variable patterns, without a signal function, and gradually become standardized (and sometimes exaggerated) as their signal function develops. They all become hostile signals; and most of them become closely associated with particular calls. These processes result in the formation of many different displays. Both young Franklin's Gulls and young Ring-billed Gulls have acquired complex repertories of hostile displays by the time they first begin to fly. The repertories of the young juvenile birds of the two species are very similar; but neither is identical with the corresponding behavior of adults. It has not been possible to trace the complete development of the adult displays (as hostile behavior declines after fledging) ; but some of the adult patterns are more or less similar to particular juvenile displays, and it may be assumed that they are derived from the juvenile patterns they most closely resemble.
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Studies On Detour Behaviour
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Experiments were performed on 28 pups, 32-131 days old, both male and female, from 8 litters (5 bitches and 8 male dogs). The pups were controlled from birth and housed in large boxes where they had no occasion to go round any objects. Experiments were carried out in an empty room in the garden; the experimental place was partially divided into 2 parts by a partition of wire-netting (fig. I). At first preliminary training was performed. II pups were allowed to remain singly for 10-15 min. daily in the part in front of the partition only and 12 pups (8 of them trained singly and 4 in pairs)- in both parts of the compartment. The other 5 pups (3 of them trained singly and 2 as a pair) were at first allowed to run round a wire-net fence in the garden and then for several daily experiments, they remained singly in a room, in front of the partition only. At the beginning of every experiment, the animals usually received food in a bowl which was always put before the wire-net partition (circle in fig. I): when the dog finished eating, the bowl was immediately taken away. After some days a key experiment was performed. This consisted in placing the bowl behind the wire-net partition (circle with cross in fig. I), so that the pup had to make a detour round the partition to reach food. The key experiment was performed separately for each animal. It was found that most pups which were previously allowed to remain in the whole experimental place or which previously went round a fence in another situation, knew how to find the way round the partition to reach food. This task was easiest for pups preliminary trained in pairs. The animals however which had previously remained only before the partition and never made a detour round any object did not know how to go to the bowl and they found the way to food only by chance, according to the "trial-and-error" principle. These pups however were capable of learning how to make a detour round the obstacle; nevertheless about 6 experiments were required to make the reaction immediate (diagram I). Pups which had learned to make a detour round a definite obstacle knew also how to do it when the size and shape of the obstacle as well as the direction of going round it were changed; the pups knew in addition how to make a detour in other situations (in other room or in the garden). Each change caused a temporary increase in the time required to go round the obstacle. In 3 pups chronic extinction of the detour reaction was performed in the garden by setting an empty bowl behind the wire-net obstacle, i.e. the detour way discontinued to be reinforced. After about 50 repetitions of such a procedure over 20 days, the detour reaction was completely extinguished. After transferring the experiments to the room the pups showed a complete (1 animal) or almost complete (2 animals) inhibition of this reaction. After the restoration of the detour reaction in the garden, it become als renewed in the room. The conclusion drawn is that the detour reaction is a locomotor conditioned reflex which is acquired by an animal usually early in its life; this reflex is then widely generalized, i.e. it may appear in all conditions similar to those to which it was primarily established. Such a view makes understandable some facts obtained during the course of experiments, as the interruption of eating by a pup in order to go behind the wire-net partition or going there immediately after eating in spite of the absence of the bowl behind the obstacle (fig. 6) ; stopping in the place of the previous passage after a lengthening of the obstacle (fig. 9); going to the old feeding place when the bowl was put in another spot (fig. II). It is very probable that pups which were allowed to remain in the whole experimental compartment or to go round a fence in another situation during the preliminary training, acquired this reaction on the basis of an exploratory unconditioned reflex (in the case of singly trained pups) or a social unconditioned reflex (in the case of pups trained in pairs; it was frequently observed that both animals found themselves on opposite sides of the obstacle and one pup came to the other).
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The Form and Duration of the Display Actions of the Goldeneye (Bucephala Clangula)
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1. The display actions of the Goldeneve (Bucephala clangula) have been analyzed from motion picture film. A name was given for each movement and the durations were measured. A record is also given of the probable order of the appearance of the actions during the spring. 2. The display actions are divided into two categories. The first includes all actions seen as F l o c k D i s p l a y s. These displays include 12 male actions and 5 female actions. The second category, P r e c o p u l a t o r Actions and C o p u l a t i o n, includes 9 male actions and 2 female actions. 3. The analysis of the display movements of the Goldeneye has shown that each is a stereotyped action. In most cases the duration of the movement has proven to be the most accurate measurement of this rigidity, however, the form of each movement has also been studied. The advantage in studying durations is that they can be easily and objectively measured, whereas no objective method of analyzing form has yet been found. 4. Some movements were found to be exceedingly constant in both form and duration. In contrast others, although constant in form, vary in duration. Even more interesting is the fact that very similar actions may be split into two types; some on the basis of form, and others on the basis of duration. 5. In contrast to virtually all of the other display actions in this species, some of the actions of the female are quite variable in both form and duration. There is the possibility that these movements cannot be clearly separated and classified.
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Social Interactions in Discrimination Learning With Special Reference To Feeding Behavior in Birds
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A full understanding of the ontogeny of species-specific food preference requires a knowledge of the effects of social interactions on discrimination learning. In this study, learning rates and processes were compared in paired and single birds. The term "empathic behaviour" has been proposed to cover all forms of motor mimicry. Processes involved may include conditioning, social facilitation, local enhancement or visual imitation, though these distinctions are not fundamental. There is evidence supporting the operation of all these in avian behaviour, except the last. Greenfinches (Chloris chloris) were trained to feed from one of two patterns and to avoid the other, with whole and aspirin-filled sunflower seeds serving as positive and negative reinforcement. Single birds learned the discrimination rapidly, as did birds which had been allowed to observe a previously trained bird performing. Birds which were being trained in the presence of an untrained partner, however, required much longer. When birds of this last group were permitted to observe the training sequence of their untrained partners, their performances, which had previously been correct, repeatedly fluctuated to a random or nondiscriminatory level. The partners, in turn, then also began to fluctuate between random and non-random levels. Behavioral data preclude the operation of local enhancement or social facilitation. Thus, the results are interpreted to mean that, under the conditions that prevailed, a feeding response can be established more readily than an avoidance response, apparently as the result of conditioning (the unconditioned stimulus being the sight of another bird feeding). The suggestion is made that birds which show this type of learning pattern in nature will prove to be conservative in their feeding habits when compared with opportunistic species whose learned avoidance responses should be more stable.
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Observations On the Flight Activity of the Red Locust, Nomadacris Septemfasciata (Serville)
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From 1953 to 1956 observations were made on the flight activity of non-swarming populations of the Red Locust, Nomadacris septemfasciata (Serville) in the Rukwa Valley, Tanganyika, a recognised outbreak area of this species. An attempt was made to obtain quantitative as well as qualitative data on flying locusts. Observations were also made of air temperatures and locust body temperatures, relative humidity, wind speed and light intensity. No flight was seen at air temperatures below 18°C. and it is considered that the minimum permissive thoracic temperature for forced flight was about 20°C. Extensive spontaneous flying was common only between air temperatures of 29°C. and 35°C., being reduced at higher temperatures. Sustained flight usually occurred only in bright sunshine. Flight was seen at all relative humidities from 12% to 80% and a seasonal variation in the humidities at which flight occurred appeared to result from a close correlation of humidity with temperature. Marked displacement of whole populations was observed only when the saturation deficit was low. Extensive flying occurred only at wind speeds not exceeding 3 m.p.h. whereas, in general, locusts that had fed recently flew less. The state of maturity also affected flight, which was least in fledglings and mature females. High-density populations flew in conditions considered unsuitable for flight in those of lower densities. Fanning was seen to occur mainly at temperatures considered too low for flight. It was regarded as a response to stimulation in conditions that raised the threshold for flight. Take-off occurred in lulls in the wind and was probably initiated by a sharp rise in body temperature following the dropping of the wind. At higher wind speeds the speed itself may be important. Other factors causing sharp temperature changes may also promote take-off. The movement of locusts from the roosts was associated with the first marked increase of body temperature relative to air temperature. It was regarded as a special case of take-off promoted by a sharp increase in temperature, all the locusts being similarly conditioned to temperature at this time of day. After moving from the roosts, the locusts were less active, the reduction in activity being associated with a period of feeding and also with temperatures relatively high for locusts conditioned overnight to low temperatures. Extensive flight started later in the day. In March-June, population displacement resulted, but later in the year the activity did not lead to marked displacements. The beginning of extensive flight was related to the end of feeding and possibly also to conditioning to higher temperatures. Late in the afternoon the migratory flights became less extensive and led to roosting. This was always associated with falling body temperatures. Flight stopped at temperatures much higher than those at which it began. This was probably due to conditioning, as was the seasonal variation in the temperature at which the last flight occurred. Active feeding at this time may also have reduced flight. Flight direction was studied, using the mirror method to provide quantitative data. Wind speed and direction were found to be important. At low wind speeds, the locusts were orientated predominantly upwind, at higher wind speeds predominantly downwind. The evidence suggested that the sun was not important in the determination of orientation, but that it might assist, through a sun-compass reaction, in maintaining a particular orientation despite short term fluctuations in wind direction. Humidity probably played no part as a directing influence during these observations, but it could not be excluded as a possible factor under some circumstances. Landscape features were thought to be unimportant in orientation except in so far as they affect wind speed and direction. The finer structure of the grasslands, however, probably elicited an optomotor reaction which made orientation to wind possible. Movements to and from the roosts were visually directed. Gregarious alignment helped to maintain a given orientation, while mutual stimulation promoted flight in high winds and so might be virtually responsible for a downwind orientation at high densities. Displacements of the locust population were studied by marking and recovery methods. The results supported the conclusions drawn from the study of factors affecting flight direction. Locusts in low density moved into the wind. Having reached particular areas, characterised by large stands of Echinochloa, they became relatively static and concentration resulted. The high-density populations were displaced downwind since they often flew in winds too high for upwind orientation on the optomotor theory. The buildup of swarm-density populations by "real" concentration of adults appeared to be a characteristic of Nomadacris in the Rukwa Valley.
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Jugendentwicklung Eines Kapuzineraffen (Cebus Apella L.) Mit Besonderer Berücksichtigung Des Wechselseitigen Verhaltens Von Mutter Und Kind
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1. Ein im März 1957 geborener, männlicher Kapuzineraffe wurde mit der Mutter zusammen ein Jahr lang beobachtet. Das Auftreten der einzelnen Verhaltensweisen und deren Variationen, sowie die Verhaltens-Verschränkungen von Mutter und Kind wurden beschrieben. 2. Die Phase der ausschliesslichen Anklammerung an die Mutter dauerte etwa fünf Wochen. Gegen Ende dieser Phase krabbelte das Baby auf dem Rücken der Mutter umher und begann von dort aus seine Umwelt taktil zu erforschen. Das Muttertier unterstützte das Klettern des Jungen auf ihrem Rücken und war so weitgehend von den Brutpflegehandlungen in Anspruch genommen, dass es kein Spielverhalten zeigte. In der 4. u. 5. Woche begannen die Abwehrbewegungen der Mutter gegen das Saugen und Krabbeln des Babies und das Schwanzfesthalten. 3. Der Übergang von dem dauernden körperlichen Kontakt zum selbständigen Klettern vollzog sich relativ rasch. Das Junge bewegte sich zunächst in der Nähe der Mutter am Boden oder auf den Sitzbrettern und wurde von der Mutter stets am Schwanze festgehalten. 4. Die einzelnen Fortbewegungsweisen traten in folgender Reihenfolge auf : Aufwärts-, Abwärts-, Seitwärtsklettern, Springen, Laufen, Hangeln und Astklettern. Im Alter von 12 Wochen waren die Bewegungen des Jungen weitgehend koordiniert. Die Mutter verfolgte anfangs aufmerksam die Kletterübungen des Babies und hielt das Junge von der 10. Woche an nicht mehr am Schwanze fest. Die Lösung des Mutter-Kind-Kontaktes vollzog sich weitgehend unter dem Einfluss des zunehmenden, antagonistischen Verhaltens der Mutter. - Die adulten Männchen trugen ebenfalls das Junge auf ihrem Rücken. 5. Bewegungsspiele, Spiele mit Gegenständen und Kampfspiel-Verhalten wurden beschrieben. 6. Einige Angaben über die Entwicklung körperlicher Merkmale, besonders über die Reihenfolge der Bezahnung, wurden angefügt.
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