Conspecific Groups Research Articles

Utilization of surrogates to integrate hand-reared infant gorillas into an age/sex diversified group of conspecifics

Mother-rearing for captive gorillas is the optimum social environment for an infant. When this is not feasible, it is important to integrate hand-reared infants as early as possible into age/sex diversified groups of conspecifics. To prepare infants in this study for introduction, the interactions of a successful gorilla mother/infant dyad were incorporated into the nursery protocol for hand-reared infants. By utilizing female gorillas over the age of 25 as surrogates, hand-reared gorilla infants were introduced into an established age/sex diversified group. The utilization of older female gorillas as surrogates may facilitate the integration of hand-reared infants and increase their potential for social success in captive populations. This report is a chronological account of the introduction process used to integrate a hand-reared male infant gorilla into an established group of conspecifics (3.3). The report includes notes on how the process was used and modified to introduce three other nursery-reared infant gorillas into the same group of conspecifics. Ape-House and Nursery personnel monitored all phases of the introduction process.

Waser’s Gas Model Applied to Associations between Red Colobus and Diana Monkeys in the Taï National Park, Ivory Coast

We performed a study on the association between a group of red colobus monkeys (Colobus badius) and a group of Diana monkeys (Cercopithecus diana) in the Taï National Park, Ivory Coast. The groups spent more than 62% of observation time together. We were able to show that the association rate was higher than would be expected on the basis of chance encounters alone by comparing the observed data with a null model known as Waser’s gas model. The two study groups had almost identical home ranges and hardly ever associated with conspecific groups. The red colobus group was primarily responsible for the initiation and maintenance of associations. At another site in West Africa (Tiwai Island, Sierra Leone), these species did not associate more often than expected by chance. The predation pressure on Tiwai Island is considerably lower than in Taï. This suggests that reduction of predation risk could be the main ultimate cause for association between red colobus and Diana groups in Taï.

Machiavellian intelligence

The hypothesis that intelligence is an adaptation to deal with the complexity of living in semi-permanent groups of conspecifics, a situation that involves the potentially tricky balance of competition and cooperation with the same individuals, has been influential in recent theorizing about human mental evolution. It is important to distinguish among distinct versions of this general idea, for they predict different cognitive consequences and apply to different species of animal. Empirical support is strong in primates for links between (i) social complexity based on evolved tactics that require a good memory for socially relevant information, (ii) neocortical enlargement, and (iii) size of social groupings. However, the evolution of computational thought and the ability to understand other individuals' intentions are not well explained as products of selection for Machiavellian intelligence. Quite different explanations may therefore be required for increases in intelligence that occurred at different times in human ancestry.

Smolt characteristics of small first-time migrant, and resident Arctic charr, Salvelinus alpinus (L.), from a river system in northern Norway

Smolt characteristics were investigated in sympatric anadromous and resident Arctic charr. Salvelinus alpinus (L.), of a similar size (11-20 cm), A group of first-time migrant anadromous charr was caught while descending the Hals River and two groups of resident conspecifics were caught in Lake Storvatn. one before, and one after, the sea-run of anadromous fish had terminated. When sampled immediately after capture in fresh water the anadromous group had a higher proportion of fish visually classified as smolts. and these charr had higher gill Na+-K+ ATPase activity, higher densities of developed chloride cells in the gills, a lower condition factor, and lower plasma osmolality, than resident fish. When exposed to sea water (33%o S), only minor differences in mortality and plasma electrolyte levels were observed between anadromous and resident fish, average values of plasma osmolality and chloride concentrations being 377 mOsm and 169 mM and 387 mOsm and 174 mM, respectively. The results suggest that the first-time migrant Arctic charr had undergone some of the physiological changes that are considered typical for a parr-smolt transformation before they left fresh water. Such changes did not appear to have occurred in sympatric, resident, fish of a similar size. The parr-smolt transformation in the first-time migrants may, however, have been incomplete, because the fish did not appear to have the ability to rapidly re-establish osmo- and ionoregutatory homeostasis after direct transfer to sea water.

Vigilance in the Tufted Titmouse Varies Independently with Air Temperature and Conspecific Group Size

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The behavior of singly-caged, yearling rhesus monkeys is affected by the environment outside of the cage

Numerous studies have demonstrated that the behavior of singly caged laboratory primates can be positively affected by inanimate enrichment within the cage. The environment outside of the cage may also influence the behavior of singly caged rhesus monkeys. To test this, we compared two cohorts of yearling rhesus ( Macaca mulatta); one that had only limited stimulation in the environment outside of the cage (singly caged in indoor rooms), and one that had considerable naturalistic and social stimulation in the extra-cage environment (singly caged in an outdoor building). Half the animals in each housing condition received a three-phase enrichment program and the rest served as controls. Subjects that had sensory access to social groups of conspecifics spent significantly more time drinking, feeding, and behaving abnormally, and significantly less time inactive and playing than did subjects that only had sensory access to other singly caged rhesus. Enriched subjects in both settings spent significantly more time playing and less time self-grooming than did controls. There was also a significant interaction for time spent in play, with enriched subjects living indoors playing the most. Although subjects that received considerable stimulation from outside of the cage spent more time engaged in abnormal behavior, most was pacing; usually in response to human manipulations of the other monkeys in the colony. Subjects housed indoors, with limited extra-cage stimulation spent less time pacing, but more time in potentially injurious abnormal activities. Among enriched subjects only, those housed indoors spent less time drinking and behaving abnormally and more time playing and using enrichment. Inanimate enrichment within the cage led to consistent positive changes in behavior for singly housed rhesus. Although the environment outside of the cage was shown to influence behavior, it was not clear whether exposure to numerous social and naturalistic stimuli was preferable to more limited stimulation for promoting well-being. Although the increased stimulation associated with a complex extra-cage environment is usually considered beneficial, not all such stimulation is positive. Frequent disturbances to social groups in view of singly caged subjects resulted in increased pacing, but the complex extra-cage environment also provided subjects with more opportunities to express and observe components of the species-typical behavioral repertoire.

Sponge/Shell Switching by Hermit Crabs, Pagurus impressus

Although hermit crabs are cited as obligate users of gastropod shells, some also use portable sponge shelters. At Dog Island, Florida, in the NE corner of the Gulf of Mexico, the hermit crab Pagurus impressus occupies sponges, commonly found near shoreline in January. However, testing of P. impressus in conspecific groups and in a mixed-species assemblage (with P. longicarpus, P. pollicaris, and Paguristes hummi) confirmed that individuals of P. impressus do not prefer sponge shelters. Hermit crabs in sponges sometimes abandoned them for shells and those in shells rarely switched into sponges. Individuals of P. impressus, especially juveniles, may occupy sponge shelters due to competition from more aggressive species and/or shell-scarcity. Additional key words: sponges, Porifera, Decapoda, symbiosis, Gulf of Mexico Most pagurid hermit crabs live in empty gastropod shells, but certain species use sponges which grow on gastropod shells. The shells may be empty or occupied by either the living snail or a hermit crab. As the sponge overgrows and encloses the shell, the hermit crab uses less of the shell, occupying instead a spiralshaped chamber within the sponge and maintaining a sculpted opening to the outside (Fig. 1). These sponges, referred to in the literature as mobile sponges (van Soest 1993), are the most common sponges in some sandy or muddy bottom habitats (van Soest 1993). Portable sponge, a better name for a sponge transported by a living snail or hermit crab, will be used to refer to such sponges in this paper. This association between pagurid and portable sponge is distinct from that of hermit crabs in the genus Cancellus, which typically do not occupy shells, but instead use a variety of shelters including pieces of rock or coral, or crevices and natural chambers in other kinds of sponges (Mayo 1973). Associations between hermit crabs and portable sponges are known from the Western and Northern Pacific (Benedict 1900; Hart 1971), Chilean coast (Desqueyroux 1972), Central Atlantic (Diaz et al. in press), Eastern Atlantic (Vosmaer 1933; van Soest 1993), Scotland (Scott 1885), and Korea (Sim 1990). The best-known association involves the sponge Suberites domuncula, a Mediterranean-Eastern Atlantic species (van Soest 1993). The Florida hermit-crab sponge, as it is commonly called by local biologists (Rudloe 1984, 1991), is a compact portable sponge of uncertain taxonomy found in the NE corner of the Gulf of Mexico (Sandford 1994). It grows on gastropod shells of several species (Wells 1969; Sandford, unpubl. data), but most commonly uses the buccinid whelk Cantharus cancellarius as a substrate (Sandford 1994 and unpubl. data). Sponges are found growing on all sizes of shells (Sandford, unpubl. data), including large shells with a thin overlying sponge layer and small shells embedded in larger sponges (Fig. 1). Several hermit crab species may inhabit the sponge, but only Pagurus impressus Benedict 1892 is common in sponges found near shoreline in January, when they are relatively abundant and when most field work over the past 8 years has been done. Daily shoreline surveys for 2 weeks in July 1993 found few sponges, most in poor condition. The association between sponges and hermit crabs has been largely unstudied since first described by Wells (1969). Little has been reported on behavior of pagurids in sponge shelters, except for conjectures on possible benefits. Vosmaer (1933) assumed a mutualistic relationship between Suberites domuncula and hermit crabs, with the sponge gaining food and oxygen, and the crab benefitting from long-term protection in a living, growing shelter. Hart (1971), commenting on Pagurus stevensae from British Columbia and the sponge Suberites ficus, mentions that a hermit crab would not have to change shelters, implying that hermit crabs in living sponges might benefit from reduced e ergy costs and predation risks associated with a need to locate and contest larger shells. Such shell-switching by hermit crabs has been well documented (Wilber This content downloaded from 157.55.39.105 on Fri, 07 Oct 2016 04:29:17 UTC All use subject to http://about.jstor.org/terms

Analysis of phase-related changes in behaviour of desert locust nymphs

An assay is developed in which the behavioural responses of an individual locust to a group of conspecifics are used to derive an index representing the ‘behavioural phase status’ of that insect. The index is generated from logistic regression models based on 11 behavioural parameters. Data are presented for locusts reared under crowded conditions for many generations and in isolation for one, two and three generations. Crowd-reared locusts differ in behaviour from insects reared in isolation in several ways. They tend to be attracted by a group of locusts, whereas insects reared in isolation are repelled. Solitaryreared locusts also show a characteristic set of behavioural responses which are all consistent with a cryptic lifestyle. Such responses become more evident with increasing number of generations of rearing in isolation. These data represent the most integrated behavioural analysis of locust phase differences yet undertaken. The procedure will be used in future work to quantify the dynamics of gregarization in congregated solitarious locusts. This will provide a much-needed basis for studying underlying controlling mechanisms, the nature of which is at present unclear.

Identification and ecology of bacterial communities associated with necroses of three cactus species

To compare the bacterial communities residing in necrotic tissues of columnar cacti of the Sonoran Desert, isolates from 39 organ pipe, 19 saguaro, and 16 senita cacti were obtained. The isolates were clustered into 28 conspecific groups on the basis of their fatty acid profiles. The distributions of the individual bacterial isolates varied among cactus species. Seven of the 28 species groups were unique to a particular cactus species, whereas 8 species groups were found in all three cacti. The effective number of bacterial species for each cactus species was positively correlated with both the chemical complexity and glucose concentration of the plant tissues. The effective number of bacterial species and bacterial distribution patterns were compared with those known for communities of cactophilic yeasts. The observed bacterial distribution patterns are most likely due to differences in the chemical compositions of the three cactus species.

Larval settlement patterns and preferences by domino damselfish Dascyllus albisella Gill

In open populations, larval settlement dynamics may be an important determinant of subsequent distribution and abundance of juveniles and adults. A correlative and experimental study of larval settlement in the domino damselfish Dascyllus albisella Gill onto coral reefs off Oahu, Hawaii, was conducted by considering settlement patterns and the extent of larval habitat choice. Conspecific groups live in transient groups on small, branching coral heads and do not interact with adults. By repeatedly censusing a natural patch reef over two summers, and employing a multifactorial experiment on a grid of isolated coral heads, I identified conspecific juvenile density as a major factor influencing settlement. A series of field and laboratory binary choice experiments confirmed that larvae preferred to settle with larger groups of conspecific juveniles than with single conspecifics, emty coral heads or confamilial groups. The laboratory experiment also indicated that preferences may have been established through visual cues, suggesting that vision may supplement chemical cues in facilitating larval settlement preferences. On a larger spatial scale, patterns of settlement at five sites coverig 25 km of Oahu's coastline suggested that two distinct peaks of larval settlement occurred in the summer of 1989 and that settlement was synchronous among these sites. It appears that settlement patterns of a small (within-reef) scale are influenced by larval habitat preferences, while settlement on a larger scale (several reefs) may be synchronized as a result of oceanographic factors or spawning patterns.

A key phase in the recruitment dynamics of coral reef fishes: post-settlement transition

Recent studies of recruitment dynamics in demersal fishes have placed major emphasis on presettlement mortality, and little on events bridging late larval and early juvenile periods. Observations on 68 taxa of Caribbean coral reef fishes before and during settlement revealed the existence of a distinct post-settlement life phase called the transition juvenile, associated with the act of recruitment. Transition juveniles were found as solitary individuals, in conspecific groups, or in heterospecific groups. The groups were either uniform or heterogenous in appearance. The complexity of the transition phase and its apparently widespread occurrence in coral reef fishes suggests that important aspects of population structure may be determined between settlement and first appearance as a full-fledged juvenile.

Social motivation in Japanese quail coturnix coturnix japonica chicks selected for high or low levels of treadmill behaviour

Social motivation (as measured by a visually isolated chick's tendency to establish visual contact with, move towards and remain in proximity to a group of conspecifics) was assessed in lines of Japanese quail which had been selected for high (HSR line) or low (LSR line) levels of an index of treadmill behaviour which combined the tendency to run towards conspecifics with the tendency to move away from them. HSR line chicks peeded sooner and more frequently before establishing visual contact with conspecifics and spent more time close to conspecifics after visual contact had been established than LSR line chicks. HSR line chicks also tended to have shorter latencies to establish visual contact with conspecifics, jump more and interact more with conspecifics than LSR chicks. It is suggested that these results indicate that selection for treadmill behaviour, which is considered to be a measure of social reinstatement tendencies, has influenced overall levels of social motivation. Furthermore, it would also appear that the phenotypic differences between the HSR and LSR lines are relatively intensive to genotype x environment interactions.

Information transfer and the facilitation and inhibition of feeding in a schooling fish

Recent studies show that fish forage actively when perceived risk is low, but decrease foraging and increase vigilance when perceived risk is high. Isolated juvenile chum salmon,Oncorhynchus keta, were visually exposed to groups of conspecifics engaged in different activities to examine their ability to gain information about foraging opportunity and risk by interpreting conspecific behavior. Isolates ate most when exposed to feeding groups, less when exposed to nonfeedig groups, and least when exposed to alarmed groups. Isolates exposed to alarmed conspecifics also spent more time motionless than did fish exposed to either feeding or nonfeeding conspecifics. These findings indicate that schooling fish gain information by interpreting conspecific behavior, and are consistent with research showing that animals balance the conflicting demands of foraging and vigilance.

Behavioural and growth responses to the intensity of intraspecific social interaction among medaka, Oryzias latipes (Temminck and Schlegel) (Pisces, Cyprinodontidae)

When access to food is restricted, faster growing fish may be those whose behaviour is relatively unaffected by the presence of nearby conspecifics. Behavioural experiments were carried out to determine the relation between growth and motor activity levels in crowded and uncrowded conditions, and measures of aversion/attraction to groups of conspecifics. Two experimental groups of Or)‐ius laripes (Temminck and Schlegel) were grown for several weeks in two environments manipulated so as to maximize differences in social interactions. In the high interaction environment (HI), food was provided inside a floating cork ring. In the low interaction environment (LI), food was spread over the container's surface. Fish were measured at the end of the growth period and tested for their activity levels in the presence of conspecifics and for their preference for, or tolerance of crowded conditions. The correlation between motor activity and growth was significantly more positive in the HI environment than in the LI environment. The relationship between preference for crowded conditions and growth was negative for both groups of fish, although less so for HI than for LI. We conclude that artificial selection for faster growth may produce more aggressive fish only under very high levels of forced social interaction (competition), if at all. Under conditions of reduced social interaction, the social‐aversive or socially indifferent fish grow faster.

Mixed-species grouping in Thomson's and Grant's gazelles: the antipredator benefits

Thomson's gazelles, Gazella thomsoni, and Grant's gazelles, G. granti, in the Serengeti National Park, Tanzania, frequently associate in mixed-species groups. Males are more likely to associate than females. Here the antipredator benefits of such associations are investigated. Compared with remaining as a smaller group of conspecifics, joining Grant's gazelles to form larger mixed-species groupss had several advantages for Thomson's gazelles. First, they were less vulnerable to cheetahs, Acinonyx jubatus, one of their main predators, as a result of improved predator detection, the lower success rate of cheetah hunts and the tendency for cheetahs to avoid hunting larger groups. Second, the Thomson's gazelles in mixed-species groups shared vigilance to some extent with the Grant's gazelles, leaving more time available for feeding. However, compared with joining conspecifics, joining Grant's gazelles to form mixed-species groups had few additional advantages and such associations were likely to be beneficial only when the number of conspecifics in the resulting mixed-species groups was relatively high. Associating with Grant's gazelles did not, for example, enable individual Thomson's gazelles to spend less time vigilant than associating with the same number of conspecifics. Grant's gazelles benefited from the association because the cheetahs' preference for the smaller Thomson's gazelles reduced the rate at which the Grant's gazelles were attacked when in mixed-species groups.

Perception of Species-specific Vocalizations by Isolate-reared Buegerigars (<em>Melopsittacus undulatus</em>)

Budgerigars were trained with operant conditioning procedures to discriminate among sets of calls from several species in a Same-Different task. Response latencies from this task were analyzed in several ways including multidimensional scaling (MDS) and cluster analysis. The pattern of response latencies from budgerigars reared in a large group of conspecifics was compared to that of budgerigars reared in acoustic and social isolation. Results show that budgerigars with previous experience with species-specific vocalizations and isolate-reared birds who had never heard such sounds can both discriminate among the categories of species-specific vocal signals. But, results from MDS and cluster analysis also show that rearing budgerigars in isolation has subtle effects on the perception of these categories of vocal signals.

A metric analysis ofCercopithecus aethiops dentition

Normative adontometric data are presented on a sample of 100 adult Cercopithecus aethiops(51 male, 49 female). When correlation effects among the teeth were held constant through multivariate canonical analyses, contributions of individual tooth loci to the male-female distance were found to be similar to those isolated by univariate means. The present study fails to support Garn’s field theory of sex dimorphism. When these patterns of sexual dimorphism were contrasted with those of three other conspecific groups, the anterior teeth were found to show greater intrapopulation variation than the posterior teeth. This, together with the finding that Penrose’s shape distances between the groups were greater for anterior than postcanine teeth, provides evidence in support of Suole’s hypothesis. The latter suggests, inter alia, that high coefficients of variation indicate a proportionately higher environmental than hereditary contribution to phenotypic variation. Negative correlations between tooth size and coefficients of variation suggest that tooth-size variability is related to size rather than occlusal complexity.

Predatory Behavior and Competition Among Laboratory-Housed Largemouth and Smallmouth Bass

moides) and smallmouth (M. dolomieui) bass were studied in order to document behav.. ioral patterns associated with locating, capturing and ingesting prey, and to evaluate differential responses to a regime of forced competition for limited food. The analyses focused on the behavioral differences associated with (a) different prey species; (b) prey size, and (c) microhabitat. Cinematography aided in the identification of species-specific searching and prey-pursuit behavioral patterns. Both species were able to capture prey using different combinations and sequences of basic functional jaw and head movements. Differences in the relative lengths of jaw bones were not reflected in a difference in the total range of prey sizes consumed by adults of the two species, but rather appeared to affect the efficiency by which various feeding modes were performed (e.g., biting, engulfing and suction). Under the competitive feeding regime, largemouth bass captured significantly higher proportions of large prey and fewer small prey than smallmouth bass in the mixed-species subadult groups. Adult basses exhibited no significant difference in the frequencies of prey captures on the basis of prey size, but did capture prey at significantly different rates from four microhabit/lts in the mixed-species group compared to the conspecific groups. Adult basses of the two species also exhibited significant differences between groups (mixed vs. single species) in the relative proportions of feeding modes used in capturing prey. For each species, there was a significant relationship between the proportions of the feeding modes used and the microhabitats where prey were seized. The microhabitat niche overlap value was 0 = 0.91 for the single species adult groups and 0 =.77 for the mixed-species adult group. Subadult basses did not separate spatially, but rather exhibited lower niche overlap for the prey size dimension in the mixed-species groups (0 =.74), compared to the single species groups (0 = .95). No significant pattern of differential prey captures between bass species was observed on the basis of the five prey species offered. The relationships between morphology, environment foraging efficiency, and behavioral variability are discussed with reference to their potential roles in natural settings.

Effects of social isolation on aggressiveness in fish with special reference to the swordtail (Xiphophorus helleri)

The attack readiness of socially isolated male swordtails ( Xiphophorus helleri ) was measured in two different aggression tests: (a) In the standard–opponent test the aggressive responses to a small, rather passive opponent swimming in a small adjacent compartment of the test aquarium were counted. (b) In the mirror test the subjects were confronted with their own mirror image. Social isolation for 4 weeks resulted in a decrease of attack readiness in both test situations. It is concluded that -- similar to cichlids -- external stimuli from conspecifics are essential for maintaining the level of aggression readiness characteristic for socially living males. There are good reasons to propose that the effect of external stimuli is mediated by the pituitary-gonadal axis. On the other hand, it is well known from previous studies that, in escalated encounters between freely swimming males, isolated males fight longer and at higher intensities for rank-order position than non-isolated males. The hypothesis is proposed that the high fighting intensity of previously isolated males could be due to an experience levelling effect of social isolation, i.e. the influence of different agonistic experience is reduced by isolation. A critical review of the literature on isolation-induced decremental and incremental effects on aggression in teleosts is presented. Often it is extremely difficult to compare the results of different authors because the methods of behavioural measurement differ to a large extent. However, it is a striking fact that social isolation of immature fish in all known cases has resulted in an increase of aggressiveness. Probably in mature males, depending on species and circumstances, either an incremental or a decremental effect of social isolation may be adaptive. On the one hand, a spontaneous increase of attack readiness may be advantageous for defence of a territory or a position in the social hierarchy and improves the ability of a single individual to join a group of strange conspecifics. On the other hand, it may be economic to lower the level of androgenic hormones to some extent in the absence of conspecifics, and this could lead to a reduction of the aggression level.

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

AbstractTwo questions are asked: (1) Which relation is there between the dominance hierarchy and communication? (2) Which are the dominance determining factors that are a result of group life ("group factors") and that cannot be found in pairs of animals? Melanochromis auratus, a cichlid fish from Lake Malawi, is studied under laboratory conditions as a representative model. Dominance relations in pairs of animals differ from those (between the same fishes) in groups of conspecifics. In groups M. auratus establishes and maintains a linear dominance hierarchy, of which the communicative structure is described and discussed. The number of aggressive interactions between two group members, is determined by the rank number of the actor and the reactor. Most interactions occur between rank neighbours. "Group factors" are looked for by analysing the clustering of all possible chase-interactions. Four categories of such clusterings are discussed: a preceding aggressive interaction can have an influence on high-ranked animals, the effect of such an influence is directed towards low-ranked animals. The stable hierarchy can be changed by successive circle fights. The highest-ranked group members always intervene in circle fights in order to stabilize the hierarchy, for their own benefit. This is another "group factor". An alpha animal has to spend all its energy in obtaining and maintaining its rank status. When it looses this position, it drops down the hierarchy. The benefit of the alpha place could be the reproductive succes.