Individual and collective problem-solving in a foraging context in the leaf-cutting ant Atta colombica

In this paper we investigate the flexibility of foraging behavior in the leaf-cutting ant Atta colombica, both at the individual and collective levels, following a change in the physical properties of their environment. We studied in laboratory conditions the changes occurring in foraging behavior when a height constraint was placed 1 cm above part of the trail linking the nest to the foraging area. We found that the size and shape of the fragments of foraging material brought back to the nest were significantly modified when the constraint was placed on the trail: independent of their size, forager ants cut smaller and rounder fragments in the presence of a height constraint than in its absence. This size adjustment does not require any direct sensory feedback because it occurred when the ants cut fragments in the foraging area; no further cutting was done when they encountered the constraint. This points to the existence of a template that ants store and use as a reference to adjust their reach while cutting. Remarkably, despite the decrease in the foraging material brought to the nest per capita the colony was still able to improve its foraging performance by doubling the number of transporters. This study illustrates the flexibility of foraging behavior exhibited by an ant colony. It provides a rare example of insects finding an intelligent solution to a problem occurring in a foraging context, at both the individual and collective levels.     

Breeding cycle aggression in domesticated zebra finches (Poephila guttata)

Patterns of breeding cycle aggressive behavior were examined in colonies of domesticated zebra finches (Poephila guttata). Aggressive behaviors of zebra finch pairs were low during non-nesting periods but were maintained at high levels during the three nesting periods: the incubating, hatching, and nestling periods. Defense of the nest site was the prominent functional category of aggression, followed by defense of individual distance. Defense of mate, defense of young, and defense of nesting material rarely occurred. Male and female members of pair bonds shared the duties of defense of the nest site and parental care. During observation times males exhibited greater frequencies of aggressive actions throughout the breeding cycle and females spent a greater amount of time in the nest during the three nesting periods. The pattern and functional categories of aggressive behavior in the zebra finch colonies correspond most closely to the nest site defense hypothesis for the evolution of breeding season aggression.     

Genotype and environment in the social interactions of wild and domestic “Norway” rats

Wild rats, Rattus norvegicus, (a) trapped as adults or (b) of the second generation in captivity (lab-wild), and domestic rats of two strains, were studied for 28 days in artificial colonies in large cages with attached nest boxes. Controls were kept in mated pairs in small cages. Each colony consisted of six males and six females. The interactions of the males in six colonies of trapped rats were highly “stressful;” 61% died; and most of the survivors lost weight and had greatly enlarged adrenals. In each colony, however, there was a male (an alpha) that gained in weight and spent much time, during the dark hours, in the open on the floor of the cage; and in three colonies there were also other males (“betas”) that gained in weight. The adrenals of alphas and betas weighed about the same as those of the controls. In one of the 12 colonies of domestic rats one male behaved like a wild male; but in the other colonies the males gained in body weight and their adrenal weights resembled those of the controls. In three colonies of lab-wild rats 22% of the males died, but there was no evidence of males of different status. The findings confirm that the “agonistic” behavior of domestic rats is usually much attenuated in comparison with that of the wild type; a number of methodologic implications are discussed.     

Experimental evidence for aggressive antipredator behavior in black skimmers (rynchops niger)

We experimentally studied the aggressive antipredator behavior of black skimmers Rynchops niger nesting in a salt marsh and sandy beach with the use of a live herring gull Larus argentatus. Although there were no significant habitat differences in vegetation cover, distance from the edge of the colony, or nesting density, skimmers nesting in salt marshes were more aggressive toward the herring gull than were those nesting on the beach. Aggression increased during the first three minutes of the test, and decreased slightly thereafter. Aggression levels were highest when the gull moved compared to when it was stationary. Skimmers made few responses when a person was present with the gull, but aggression increased dramatically when only the gull remained. Our results suggest skimmers may engage in more aggressive behavior in defense of their nests than previously thought, particularly when exposed to a predator that actually takes eggs and chicks. Further, we suggest that conclusions about antipredator behavior drawn only from studies of interactions with people may need further amplification. © 1992 Wiley-Liss, Inc.     

Defensive aggression in terns: Effect of species,density, and isolation

Defensive aggression was examined in seven species of terns during the hatching period when young are most vulnerable and adults most responsive. Aggression toward an unfamiliar person varied with respect to species, flush distance, approach distance, number of birds overhead and diving, and number of dives per 2 min for all birds and the nest owner. Defensive aggression involved birds circling over and diving at the experimenter. Generally, flush distance was negatively correlated with nest density, while the number of birds diving was positively correlated with the nest density. The number of birds diving was positively related to the number of dives, dives by the owner, and the number overhead.     

Nestling recognition via direct cues by parental male bluegill sunfish (<Emphasis Type="Italic">Lepomis macrochirus</Emphasis>)

Parental care can be costly to a parent in terms of both time and energy invested in the young. In species with cuckoldry or brood parasitism not all of the young under a parent's care are necessarily offspring. In such cases, distinguishing between kin and non-kin, and investing only in the former (nepotism), can be advantageous. Bluegill sunfish (Lepomis macrochirus) are characterized by paternal care and cuckoldry, and care-providing males appear to show nepotistic behaviours. Here, we investigated nestling recognition in bluegill, determining whether parental males can differentiate between young from their own nest (familiar and related) and young from non-neighbouring nests (unfamiliar and unrelated) using (1) visual and chemical cues, and (2) chemical cues only. In the first experiment, wild-caught parental males were presented with samples of eggs or fry (newly hatched eggs) collected from their own nest or a foreign nest and placed on opposite sides of an aquarium. The time these parental males spent associating with each sample, and their "pecking" behaviours (indicating cannibalism), were recorded. Parental males showed no preference between eggs from their own nest and eggs from a non-neighbouring nest, but they preferred to associate with fry from their own nest over foreign fry. There also was a positive relationship between male body size and the time spent associated with fry from their own nest. Parental males pecked at foreign fry more than 5 times as often as fry from their own nest, though this difference was not statistically significant. In the second experiment, fry that were collected from the nest of a wild-caught parental male or a non-neighbouring nest were placed in different containers and the water from each was dripped into opposite ends of an aquarium. The time the male spent on each side was recorded. In this case, parental males spent more time near the source of water conditioned by unrelated fry, but there was a positive relationship between male condition (fat reserves) and the time he spent near the source of water conditioned by fry from his own nest. Results confirm that chemicals cue nestling recognition by parental male bluegill. Electronic Publication     

The introduction of a group of alien mice (Mus musculus L.) into hierarchically organized groups of five male mice

Groups of 3 male or female Mus musculus were introduced into hierarchically organized colonies of 5 male mice for a period of 8 days. The colonies were of 2 kinds; high-level aggressive (HLA), which had been set up 3 days prior to the introduction of the aliens, and low-level aggressive (LLA), which had been established for 21 days before strangers were introduced. Both males and anestrous females were attacked, but males were attacked 5 times more frequently than females. In HLA colonies most of the attacks on the aliens were by the dominant; in LLA colonies there was no difference in the behavior of dominant and subordinate mice toward strangers. Both aggression toward aliens and intracolony aggression declined over the 8 day experimental period. In HLA colonies the dominant mouse mounted females 5 times more frequently than did either his subordinates or male mice in the LLA colonies. In HLA colonies aliens huddled with subordinates to form a single colony with 1 dominant and 7 subordinates. In LLA colonies alien males remained as a discrete group spatially separated in the cage. Female aliens were incorporated into the main colony. In all cases dominant male mice made more attacks on aliens as compared with familiar mice.     

权威与群体因素对中学生受暗示心理的影响研究

本研究在前人的基础上再次证实权威与群体是影响受暗示心理的主要因素,选取了即将参加高考的高三学生作为被试,从而证明该结论在不同的群体样本中都成立。同时也比较了两者影响作用的大小和在不同群体中的表现是否有差异。通过设计由两个群体暗示实验组、两个权威暗示实验组和一个控制组组成的实验来进行研究。研究表明在中学生群体中权威与群体都对受暗示心理有影响,但是群体的暗示作用更大,权威的暗示作用显得比较小甚至会出现相反的结果,这说明中学生和大学生相比,心理发展还处于不稳定时期,在受权威暗示上还存在一定程度的逆反心理。     

The aggression questionnaire.

A new questionnaire on aggression was constructed. Replicated factor analyses yielded 4 scales: Physical Aggression, Verbal Aggression, Anger, and Hostility. Correlational analysis revealed that anger is the bridge between both physical and verbal aggression and hostility. The scales showed internal consistency and stability over time. Men scored slightly higher on Verbal Aggression and Hostility and much higher on Physical Aggression. There was no sex difference for Anger. The various scales correlated differently with various personality traits. Scale scores correlated with peer nominations of the various kinds of aggression. These findings suggest the need to assess not only overall aggression but also its individual components.     

Geographic vocal variation and perceptual discrimination abilities in male Australian sea lions

Vocal characteristics can vary among and within populations. In species with geographic variation in the structure of vocalizations, individuals may have the ability to discriminate between calls from local and non-local individuals. The ability to distinguish differences in acoustic signals is likely to have a significant influence on the outcome of social interactions between individuals, including potentially mate selection and breeding success. Pinnipeds (seals, fur seals, sea lions and walruses) are highly vocal yet the Australian sea lion (Neophoca cinerea) is the only eared seal known to show geographic vocal variation in male barks. Barks are produced in many social interactions and encode sufficient information for both individual and colony identity to be discriminable. Yet until now, whether males could themselves discriminate these bark differences was unclear. We performed playback experiments in four breeding colonies to investigate whether males can discriminate local from non-local barks. Overall, males responded more strongly to barks from their own colony compared to barks from other colonies regardless of whether those other colonies were close or distant. Competition for females is high in Australian sea lions, but mating periods are asynchronous across colonies. The ability to correctly assess whether a male is from the same colony, thus representing a potential competitor for mates, or merely a visitor from elsewhere, may influence how males interact with others. Given the high cost of fighting, the ability to discern competitors may influence the nature of male–male interactions and ultimately influence how they allocate reproductive effort.     

Further experiments on the social interactions of domestic “Norway” rats

Domestic rats, Rattus norvegicus, aged nearly one year, were studied in artificial colonies in large cages with attached nest boxes. As in previous experiments on younger domestic rats, but not those on wild rats, the colonies were peaceful. Questions concerning the “aggressive” or “agonistic” behavior of domestic rats are further discussed.     

Components of disinhibition (vs. constraint) differentially predict aggression and alcohol use

Disinhibition (vs. Constraint; DvC), which has been shown to represent a central aspect of the externalizing domain, consists of several correlated but distinguishable underlying traits, which may have different patterns of association with various externalizing indicators. In a sample of 18‐ to 19‐year old undergraduate students (N = 430; 71.1% female), we examined the specificity and generality of the association between lower order components of DvC and both aggression and alcohol use, externalizing‐related behavioural constructs that have well‐established links to DvC. All three components of DvC—including Disagreeableness, low Self‐Control and low Accomplishment—were associated independently with Reactive Aggression, but only Disagreeableness was correlated significantly with Proactive Aggression. Also, only low Self‐Control was associated with alcohol use. Thus, aggression was broadly associated with components of DvC—although much more strongly with the Disagreeableness domain—whereas alcohol use was specifically correlated with low Self‐Control. These results suggest that lower order components of DvC have distinct patterns of associations with externalizing‐related outcomes. Copyright © 2011 John Wiley & Sons, Ltd.     

Septal lesions and biting attacks in rats bidirectionally selected for emotionality

Twenty-nine colonies composed of one female and two male rats of high or low emotional strain were established. A dominant male of each colony was identified based on its attacks on an intruder rat. It was found that dominant males of the low emotional strain colonies were significantly more aggressive than those of the high emotional strain. Septal lesions or sham operations were given to dominant males of both strain colonies. Intruder tests were followed and several aggressive behaviors were measured by VTR observation. Biting attacks of the high emotional strain decreased for 10 days after septal latencies were shortened by septal lesions. Lesions X Strain interaction was significant. These results suggest that septal lesion effects on biting attacks are influenced by artificial genetic operations.     

Bee-eaters (<Emphasis Type="Italic">Merops orientalis</Emphasis>) respond to what a predator can see

Two sets of experiments are reported that show that the small green bee-eater (Merops orientalis, a small tropical bird) can appreciate what a predator can or cannot see. Bee-eaters avoid entering the nest in the presence of a potential nest predator. In the first set of experiments bee-eaters entered the nest more frequently when the predator was unable to see the nest from its position, as compared to an approximately equidistant position from which the nest could be seen. In the second set of experiments bee-eaters entered the nest more frequently when the predator was looking away from the nest. The angle of gaze from the nest was associated significantly positively with the probability of entering the nest whereas the angle from the bird was not. Birds showed considerable flexibility as well as individual variation in the possible methods of judging the predator's position and direction of gaze. Electronic Publication     

Social dominance and individual aggressiveness

Male rats exhibiting high, moderate, or low levels of offensive aggressive behavior in interactions with intruders in their home cage were grouped in mixed-sex colonies with 1 male of each aggression-level group in each colony. Agonistic interactions measured 1, 2, 3, 7, 14, 21, and 22 days after colony formation indicated that highly aggressive males on pretests continued to be more aggressive, becoming the dominant colony male in five of seven colonies and attacking intruders more often than less aggressive males. In the two remaining colonies the moderately aggressive male became dominant. This relationship, which was consistent over a number of indices, including offensive and defensive behaviors, and wound counts and wound sites, was seen even when a substantial weight differential favored the less aggressive animal. Dominance relationships were rapidly established and within-group fighting declined significantly over the 21-day test period. Pretest offensive levels also influenced the behavior of subordinates, with high or moderately aggressive subordinates showing more defense in interactions with dominants and receiving more wounds than did low-aggression subordinates. Dominant males also showed more defense in interacting with those subordinates which had been more aggressive during pretests. This pattern of results suggests that aggression level of the subordinate as well as the dominant may be an important factor determining the intensity of agonistic interactions in male rats.     

Aggression in wood ants (Formica polyctena Foerst., Hymenoptera,Formicidae)

The relationship between aggression and predation was surveyed in Red wood ants, in the field as well as under laboratory conditions. Aggression between wood ant nests is highest in early spring, and many wood ant wars break out then. The end of these wars coincides with a strong increase in prey density. Since the casualties are taken as food to the warring nests, a hypothesis is formulated that warfare between wood ant nests only occurs in periods when prey demand exceeds the supply. Protein-rich food in early spring is mainly for the benefit of the queens and the sexual larvae. Although the most obvious function of warfare is the defence of a foraging area, the main function may be the advancement of the mating flight dates of the queens in order to make the chance of propagating their genes greatest.     

Diminished sense of self-existence and self-reported aggression among Japanese students

This study examined the relationship between a diminished sense of self-existence and self-reported aggression among Japanese undergraduate students. Based on the previous scales, 81 items were developed to measure the diminished sense of self-existence and were assumed to represent three dimensions: self, others, and time. 286 undergraduate students rated themselves on the Diminished Sense of Self-existence Scale and the 1992 Buss-Perry Aggression Questionnaire. Analysis indicated that men and women had low scores on Verbal Aggression and high scores on Hostility with the diminished sense of self-existence. The diminished sense of self-existence was not generally related to Anger or Physical Aggression in men, whereas in women, Anger and Physical Aggression were found particularly when the sense of self-existence in relations with others was diminished.     

Psychometric evaluation on the Japanese adaptation of the Aggression Questionnaire.

The psychometric properties of a Japanese translation of the Aggression Questionnaire (Buss & Perry, 1992, Journal of Personality and Social Psychology, 63, 452-459) were investigated. Factor analysis of the responses of 425 Japanese participants generally supported the four-factor model. The factors were Physical Aggression, Verbal Aggression, Anger and Hostility. The internal consistencies of the four subscales were adequate. The results suggested that the Japanese version of the Aggression Questionnaire met psychometric standards and appears to be a promising measure of aggression. However, the Japanese version may be improved if two reversed scored items are removed from the scale. The cross-cultural difference in responses between negatively-oriented and affirmatively-oriented questions was discussed.     

Jewish agricultural settlement in Brazil

Jewish agricultural colonization in Brazil began in 1904 in the state of Rio Grande do Sul, supported by the Jewish Colonization Association (JCA). The JCA created the first colonies – Philippson (1904) and Quatro Irmãos (1912) – with the intention of resettling Russian Jews during the decisive years of mass immigration from the Russian empire. In 1936, the JCA administration in Brazil proposed a new project to establish a colony for German Jews in Rezende, situated in the state of Rio de Janeiro. Similar to other initiatives undertaken by the São Paulo and Paraná state governments some years before, the Rezende colony did not last long. This essay analyzes the main factors behind the disintegration of the JCA colonies, noting that, in spite of their relative failure, the colonies aided Brazil and helped change the stereotypical image of the non-productive Jew, capable of working only in commerce and finance. The main benefit from these agricultural experiments was the removal of restrictions in Brazil on Jewish immigration from Europe during the twentieth century.     

Exploration and choice by mice among nest boxes differing in size: Influence of the inner and the outer dimensions

The size of nest boxes induces contrasting effects on exploratory behaviour and nest establishment of mice. Nest box exploration increases, and preference for nest site decreases, with increasing nest box size (Buhot, 1987). The aim of the present study was to continue the investigation of the different effects of the inner vs outer properties (here sizes) of nest boxes, the former being likely to play a major role in nest establishment, whereas the latter were predicted to be mainly involved in the initial exploratory process. The subjects were cagemate groups of two or three male mice. They were subjected to four ranking tests in which the nest boxes differed in outer size only, or in inner size only, and they either had a roof or did not have one. Among nest boxes with identical inside dimensions, the mice preferentially chose as nest sites those with the largest available outer dimensions; the presence of a roof did not affect this preference. In situations with nest boxes differing only in inner size, opposite preferences were observed, depending on whether or not a roof was present. In the presence of roofed nest boxes, mice's preferences were positively correlated with the size of the boxes. In the unroofed condition, an optimal value was observed around the second smaller inner-spaced nest box. Thus, both inner and outer properties influenced nest box choice. As a roof provides maximum safety, its presence seemed to have allowed choice to be governed by a secondary criterion—the maximum distance between the nest and the entrance. Initial exploration patterns were mainly influenced by the outer characteristics of the nest boxes: the larger the nest boxes were on the outside, the earlier and more frequently they were visited.