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Desecheo Island (117 ha) was historically an important seabird island in the Caribbean with 15 species recorded, of which seven are known to breed, including major populations of brown boobies and red‐footed bobbies. The introduction of invasive mammals, plus the use of the island as a bombing range, contributed to the extirpation of five of the seven known breeding populations of seabird species and vastly reduced numbers of the remaining two species. The island became a National Wildlife Refuge in 1976 and major conservation interventions have included the eradication of invasive goats, rhesus macaques and rats between 1976 and 2016. Removing these critical threats from the island has allowed other active restoration goals to be realized, including restoring seabird colonies to the island. Here, we report on the installation of social attraction equipment in 2018 to augment bridled tern and brown noddy colonies and establish a species of conservation concern, the Audubon's shearwater. We supported these actions through a review of historic seabird nesting and roosting on Desecheo. Motion‐sensing cameras were installed to document activity at each social attraction site and evaluate the effectiveness of our methods. During the 2 years of deployment and monitoring, a total of seven bridled tern nests were documented in new and historic sites for the species, two of them next to a decoy colony; however, no brown noddy visits or nests were detected. In 2018 and 2019, one and two Audubon's shearwaters, respectively, were attracted to one of the sound system speakers, representing the first record for this species on the island. Social attraction efforts on Desecheo appears to be a feasible activity that may help support seabird recolonization and support conservation goals for this National Wildlife Refuge.

Insistent nesting attempts by a group of European Beeeaters in a new site, a pebbly bank of the middle course of Trebbia River, northern Italy, mostly failed because of the unmovable pebbles encountered during tunnel excavation. The birds later nested in an artificial sand heap, with full success that time. Various considerations suggest that birds insisted in the unsuitable site because they copied the nesting activity of model conspecifics. Finding social attraction and “public information” from conspecifics in a place where no breeding attempt was previously made would allow disentangling social philopatry from spatial philopatry.

A sequence of different classes of synthetic insecticides have been used over the past 70 years. Over this period, the widely-used organochlorines were eventually replaced by organophosphates, with dichlorodiphenyltrichloroethane (DDT) and chlorpyrifos (CPF) as the principal prototypes. Considerable research has characterized the risks of DDT and CPF individually, but little is known about the toxicology of transitioning from one class of insecticides to another, as has been commonplace for agricultural and pest control workers. This study used adult zebrafish to investigate neurobehavioral toxicity following 5-week chronic exposure to either DDT or CPF, to or their sequential exposure (DDT for 5 weeks followed by CPF for 5 weeks). At the end of the exposure period, a subset of fish were analyzed for brain cholinesterase activity. Behavioral effects were initially assessed one week following the end of the CPF exposure and again at 14 months of age using a behavioral test battery covering sensorimotor responses, anxiety-like functions, predator avoidance and social attraction. Adult insecticide exposures, individually or sequentially, were found to modulate multiple behavioral features, including startle responsivity, social approach, predator avoidance, locomotor activity and novel location recognition and avoidance. Locomotor activity and startle responsivity were each impacted to a greater degree by the sequential exposures than by individual compounds, with the latter being pronounced at the early (1-week post exposure) time point, but not 3–4 months later in aging. Social approach responses were similarly impaired by the sequential exposure as by CPF-alone at the aging time point. Fleeing responses in the predator test showed flee-enhancing effects of both compounds individually versus controls, and no additive impact of the two following sequential exposure. Each compound was also associated with changes in recognition or avoidance patterns in a novel place recognition task in late adulthood, but sequential exposures did not enhance these phenotypes. The potential for chemical x chemical interactions did not appear related to changes in CPF metabolism to the active oxon, as prior DDT exposure did not affect the cholinesterase inhibition resulting from CPF. This study shows that the effects of chronic adult insecticide exposures may be relevant to behavioral health initially and much later in life, and that the effects of sequential exposures may be unpredictable based on their constituent exposures.

[EN] The Spanish Imperial Eagle (Aquila adalberti) disappeared from Africa as a breeding species in the 1960s coincident with a general decline of their populations in the Iberian Peninsula. Because of a combination of successful conservation actions and a general change in human attitudes, the Spanish Imperial Eagle population has been increasing in Iberia from 103 pairs in 1980 to more than 500 breeding pairs in 2018. As a consequence, the number of juveniles that cross the Strait of Gibraltar into Africa has increased recently. Abundance and distribution of potential prey should affect young eagles’ behaviour and could be a limiting factor for a potential re-colonization of previous North-African populations. Additionally, determination of temporary settlement areas is crucial from a conservation point of view. Conservation actions in these areas, particularly reduction of juvenile mortality, are a priority to facilitate future reestablishment of breeding populations of the species in North Africa. Here we report on the dispersal movements of juvenile Spanish Imperial Eagles marked with GPS-GSM transmitters in Andalusia (southern Spain), some of which crossed the Strait of Gibraltar into north-western Africa, an area that does not have populations of the eagle’s main prey, the European rabbit. We analysed the differences in dispersal patterns and temporary settlement behaviour in the two study areas. We found that dispersal movements were greater, temporary settlement areas were larger, and individuals stayed longer in areas and moved greater distances among them in Africa than in Iberia. We believe that our results are best explained by applying the Marginal Value Theorem, which predicts that individuals will leave a foraging area when the availability of prey drops to similar levels of those of the surrounding environment. We suggest that the increase in the records of the species in Africa could lead to a recolonization of the species in Africa based on birds coming from the “source” Iberian population, but only if the Iberian population continues to increase. We recommend that conservation measures must be established in these temporary settlement areas in Africa., [DE] In den 1960er-Jahren verschwand der Spanische Kaiseradler (Aquila adalberti) als Brutvogel aus Afrika, was mit einem generellen Rückgang seiner Populationen auf der Iberischen Halbinsel einherging. Aufgrund einer Kombination aus erfolgreichen Schutzmaßnahmen und einem allgemeinen Wandel der menschlichen Einstellung wuchs die Population Spanischer Kaiseradler auf der Iberischen Halbinsel von 103 Brutpaaren im Jahr 1980 auf über 500 Brutpaare im Jahr 2018 an. Infolgedessen stieg die Anzahl der Jungvögel, welche die Straße von Gibraltar in Richtung Afrika überqueren, in neuerer Zeit an. Die Häufigkeit und Verteilung potenzieller Beutetiere sollte das Verhalten der jungen Adler beeinflussen und könnte einen limitierenden Faktor für eine mögliche Wiederbesiedlung der Gebiete ehemaliger nordafrikanischer Populationen darstellen. Darüber hinaus ist aus Sicht des Naturschutzes die Ermittlung vorübergehend genutzter Ansiedlungsgebiete von entscheidender Bedeutung. Schutzmaßnahmen in diesen Bereichen, speziell zur Verringerung der Jungensterblichkeit, sind eine Vorbedingung für eine zukünftige Wiederansiedlung der Art als Brutvogel in Nordafrika. Hier beschreiben wir die Dismigrationsbewegungen juveniler Spanischer Kaiseradler, welche in Andalusien (Südspanien) mit GPSGSM-Sendern ausgestattet wurden, und von denen einige die Straße von Gibraltar nach Nordwestafrika überquerten, ein Gebiet, in dem es keine Wildkaninchenpopulationen gibt, welches die Hauptbeuteart des Adlers ist. Wir analysierten die Unterschiede in den Ausbreitungsmustern und im zeitweiligen Ansiedlungsverhalten zwischen den beiden Studiengebieten. In Afrika gab es stärkere Ausbreitungsbewegungen, die zeitweisen Ansiedlungsbereiche waren größer, Individuen blieben länger in den Gebieten und legten zwischen diesen weitere Strecken zurück als auf der Iberischen Halbinsel. Wir sind der Meinung, dass unsere Ergebnisse sich am besten durch die Anwendung des Grenzertragstheorems (engl.: Marginal Value Theorem) erklären lassen, welches besagt, dass Individuen ein Nahrungsgebiet verlassen, wenn dort die Beuteverfügbarkeit auf ein ähnliches Maß wie im Umland sinkt. Wir vermuten, dass der Anstieg in den Nachweisen der Art in Afrika dort zu einer Wiederbesiedlung durch Vögel aus der iberischen “Quellpopulation” führen könnte, allerdings nur, wenn die iberische Population weiterhin wächst. Wir empfehlen den Ausbau von Schutzmaßnahmen in diesen zeitweiligen afrikanischen Ansiedlungsgebieten.

The present study tested whether the presence of already retained fishes inside baited fish pots acted as a social attraction and affected the entrance probability of Atlantic cod Gadus morhua in a fjord in northern Norway. Video analysis revealed that the probability of an entrance initially increased with the presence of low numbers of fishes inside the pot, but subsequently decreased at a critical number of caught fishes. The critical number was dependent on the size of the G. morhua attempting to enter. This demonstrates that social attraction and repulsion play a role in G. morhua pot fishing and has important implications for the capture efficiency of fisheries executed with pots.

Capturing breeding adults of colonially nesting species can entail risks of nest failure and even colony abandonment, especially in species that react strongly to human disturbance. A low-disturbance technique for capturing specific adult Double-crested Cormorants (Phalacrocorax auritus) at a ground-nesting colony was developed to reduce these risks and is described here. Nesting habitat enhancement was used to attract Doublecrested Cormorants to nest adjacent to above-ground tunnels constructed so that researchers could capture birds by hand. Using this technique, Double-crested Cormorants (n = 87) were captured during the incubation and chick-rearing stages of the nesting cycle. Unlike alternative capture techniques, this approach allowed targeting of specific individuals for capture and recapture, minimized local disturbance, and eliminated colony-wide disturbances. The tunnel-based system presented here could be adapted to capture adults or to access the nest contents of other ground-nesting...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Many producers in the laying hen industry, including in North America, are phasing out conventional cages in response to consumer demands and sometimes subsequent legislation. Alternative housing systems such as aviaries are being implemented in an attempt to improve hen welfare. Aviaries provide additional space and resources to groups of hens, including a litter area on the floor. However, little is known about hen movement between tiered enclosures and floor litter areas in aviary systems. Diurnal rhythms and social attraction may result in peak times of movement that could lead to overcrowding of areas, or alternatively hen preferences may lead to some areas not being fully utilized. We monitored hen movement between tiered enclosures and litter areas, including movement on and off the outer perch, across the day at peak, mid and end of lay in a commercial aviary. Hens moved onto and off of the open litter area across the day, transitioning between tiered enclosures, outer perches, open litter areas, and litter areas under tiered enclosures. At certain times of day, there were periods of greater hen movement down to the open litter area and between litter areas. For example, more hens were typically observed exiting enclosures, jumping from perches to open litter, and traveling between open litter and litter under tiered enclosures in the morning (all P ≤ 0.001). In all but one instance, more hens were observed on open litter areas in the afternoon than at other times of day (all P ≤ 0.029). However, hen re-entry to tiered enclosures showed less circadian patterning. Hen movement was observed between areas of interest at all sampled time periods, indicating hens use all areas of the system. Further research should examine whether all individual hens do move between areas equally, including within levels of the tiered enclosure, or if crowding occurs on the outer perches or in the litter during times of peak movement.

Islands are biodiversity hotspots that offer unique opportunities for applied restoration techniques that have proven to bring inspiring outcomes. The trajectory of island restoration in Mexico is full of positive results that include (1) the removal of 60 invasive mammal populations from 39 islands, (2) the identification of conservation and restoration priorities, (3) the active restoration of seabird breeding colonies through avant-garde social attraction techniques, (4) the active restoration of integrated plant communities focusing on a landscape level, (5) applied research and science-based decision-making for the management of invasive alien species, (6) the legal protection of all Mexican islands, and (7) biosecurity and environmental learning programs to ensure outcomes are long lasting. Still, there are many complex challenges to face in order to achieve the goal of having all Mexican islands free of invasive mammals by 2030.

Social foraging is thought to provide the possibility of information transmission between individuals, but this advantage has been proved only in a handful of species and contexts. We investigated how social connections in captive flocks of house sparrows (Passer domesticus) affected the discovery of (i.e. feeding for the first time from) two hidden food patches in the presence of informed flock-mates. At the first-discovered and most-exploited food patch social connections between birds affected the order of discovery and presumably contributed to a greater exploitation of this patch. However, social connections did not affect discovery at the second food patch despite its close spatial proximity. Males discovered the food sources sooner than females, while feeding activity was negatively related to patch discovery. Age had no effect on the order of discovery. Birds that first discovered and fed at the food patches were characterized by higher level of social indifference, i.e. followed others less frequently than other birds in an independent context. Our findings provide experimental evidence for the importance of variable social connections during social foraging in house sparrow flocks, and suggest that social attraction can contribute differently to the exploitation of different patches when multiple food sources are present.

The Northwestern Hawaiian Islands support some of the largest tropical seabird colonies in the world, but these low-lying islands are threatened by sea level rise and increasing storm surge associated with climate change. Protection of suitable nesting habitat and creation of new breeding colonies on the higher main Hawaiian Islands are among the highest priority conservation actions for these seabirds. From 2015 to 2018, we used social attraction and translocation to begin establishing new colonies of two vulnerable seabirds, Laysan albatross and black-footed albatross, inside a 6.6-ha predator-exclusion fence at James Campbell National Wildlife Refuge, Oahu. Social attraction with decoys and playbacks of recorded vocalizations resulted in increasing visitation by Laysan albatrosses, with a maximum of 343 visits per year, and the first nesting attempt in 2017. We also translocated 50 Laysan and 40 black-footed albatross chicks to the site when they were 2–4 weeks old and raised them by hand until fledging. On average, the translocated chicks attained a higher body mass, longer wing chord, and fledged 2–3 weeks earlier than naturally-raised chicks. The fledging rate was ≥90% both species. The first translocated bird from the 2015 cohort returned to the release site in 2018, and we expect more translocated birds to return at age 3–5 years and to begin breeding there at age 7–9 years. We expect that continued social attraction of Laysan albatrosses and return of birds already translocated will be enough to establish a colony. For black-footed albatrosses, social attraction is unlikely to contribute to colony establishment during the initial stages, and we plan to translocate 40-50 additional chicks over two more years. The methods we developed to hatch, feed, and fledge albatrosses will be useful for similar projects involving translocation of other seabirds. Keywords: Albatross, Climate change, Hawaii, Seabirds, Social attraction, Translocation

Colonial nesting seabirds frequently drive island ecosystem biodiversity by maintaining ecosystem functioning and community dynamics. Invasive mammal introductions to most of the world’s islands have ravaged insular seabird populations and had associated devastating ecosystem-wide effects. Eradication programs remove invasive mammals from islands, with the goal of conserving and restoring island species and systems. However, most eradication programs rely almost exclusively on passive seabird recovery to achieve these goals. Unfortunately, the life histories of most seabird species are not conducive to passive recovery within a contemporary timeframe. Seabird restoration techniques can effectively overcome life history related issues and significantly reduce recovery times for insular seabird populations, thereby reducing associated ecosystem-wide recovery times. By integrating seabird restoration and eradication programs, practitioners can maximize conservation gains, expand funding opportunities, and restore island ecosystems and the biodiversity they support.

We investigated juvenile dispersal strategy of a territorial long-lived species with deferred maturity, the Spanish imperial eagle, Aquila adalberti. Here we used a reintroduction programme as an experimental approach to test separately predictions of the two hypotheses about natal philopatry: social attraction and local experience. We determined the maximum juvenile dispersal distance of 90 young eagles in three different categories: (1) 31 translocated young released without adults in the area; (2) 29 translocated young released with adults breeding in the area; and (3) 30 wild nonmanipulated individuals. No differences between the sexes were found but there was a highly significant difference between the three categories, with longer distances in young released without adults in the area and similar distances in the other two categories. Our results thus showed that social attraction determined the juvenile dispersal strategies in this species., The reintroduction programme was supported by GIASA, Fundación Santander, Fundación Migres and Junta de Andalucía.

We asked whether the lack of a population response by ancient murrelets (Synthliboramphus antiquus) to eradication of rats (Rattus spp.) at Langara Island could be due to a change in vegetative cover. We quantified ancient murrelet habitat associations on 12 islands and assessed changes in vegetation at Langara Island between 1981 and 2007. We found that ancient murrelets exhibit a high degree of flexibility in their use of available breeding habitats, and we noted no changes over time. Thus, recovery of ancient murrelets at Langara Island is unlikely to be limited by habitat quality. We propose artificial social attraction as a method to speed recovery. 2011 The Wildlife Society.

Social attraction, that is, mimicking of active and productive colonies via audio playback of calls of breeding conspecifics and the use of decoys, is commonly used to attract birds to newly established or restored breeding sites. However, little is known about the relative importance of aural versus visual cues for identify nesting areas. Such information is important for design and evaluation of management protocols. We studied the effectiveness of decoys (visual cues) and playbacks (audio cues) as methods for restoring a colony of common terns (Sterna hirundo) at Muskeget Island, Massachusetts, USA. We used a 2-year, crossover experiment with 3 treatment areas: audio and visual, audio only, and visual only. We reversed treatment areas in the second year to control for previous nesting area or substrate preference. In both years, nests were built 9–101 m downwind of loudspeakers. There was no overlap in areas used for nesting between years and no nests were built within decoy plots in either ye...

Social attraction is a useful technique for re-establishing or relocating waterbird colonies and other species groups. However, little information exists regarding how newly attending individuals behave when the social environment is influenced predominantly by artificial stimuli. To help assess early progress of colony re-establishment, we compared time-activity budgets of common murres (Uria aalge) at a social attraction site (Devil’s Slide Rock; DSR) in central California with two nearby reference colonies during the first 3 years (1996–1998) of efforts. Murres at all colonies spent over 95% of their time engaged in resting, comfort, courtship, and alert activities during the pre-breeding period and over 88% of their time in similar activities during the breeding period. Although patterns were similar overall, comparisons of pooled and year-specific time budget data revealed significant differences between all three colonies, especially during pre-breeding. Murres at DSR typically engaged in comfort behaviors less frequently and in alert and courtship behaviors more frequently than reference colonies. Differences likely were due to recent re-establishment, including lower bird densities and higher proportions of non-breeders and first-time breeders at DSR, along with other factors such as disturbance. Results indicate that newly attracted birds at DSR behaved “normally” even though the social environment was influenced predominantly by artificial stimuli. Furthermore, re-established breeding in the first year of efforts, subsequent colony growth, and high productivity reflected successful restoration efforts. Thus, time-activity budgets can provide important measures of early progress of social attraction efforts and as such can be used to inform adaptive management decisions.

For breeding, sand martins dig burrows in sandy cliffs. The distribution of burrows and broods is non-random in different respects. The study deals with proximate factors responsible for this feature and with the question, whether differences in breeding success are correlated with differences in the distribution of burrows and broods. A series of field experiments shows that characteristics of the cliff (upper and/or lower limit, existing burrows, ledges) and of the conspecifics (social attraction, defence of burrows) influence the birds' selection of a burrow-site and that site-attachment is also involved. Birds in the highest burrows suffer less predation by a beech marten; the breeding success is correlated with the length of the burrows and with the synchronisation of broods in the sub-colonies.

At the northern periphery of its range Brewer's Sparrow (Spizella breweri breweri) is in decline and breeds in small clusters within larger areas of suitable habitat. Clustered breeding that is unrelated to the distribution of resources may be explained by social attraction (conspecific cueing). We used a song-playback experiment to test the conspecific-cueing hypothesis in this species. The experiment was conducted during the spring settlement period in habitat that appeared physically suitable for breeding but had not been occupied during die previous two breeding seasons. Treatments were split between two periods that reflected peak settlement of experienced and first-time breeders. In both periods, more Brewer's Sparrows visited and established territories in treatment plots than in untreated control plots. There were not, however, more treatment than control plots containing breeding pairs. This difference could mean that males attracted to playbacks are of lower quality than males in estab...

Social and ecological conditions can influence flock formation (e.g. number of flocks, flock size, etc.) depending on the degree of social attraction of a species. We studied group formation in brown-headed cowbirds (Molothrus ater) over short time periods (30 min) in two seminatural experiments conducted under controlled conditions. First, we determined the shape of the relationship between intake rate and flock size by manipulating group size in a single enclosure. Second, we assessed the role of population size, food abundance, and predation risk, and their interactions, in flock size formation in a system of four enclosures (two with and two without food) connected to a central refuge patch. In the first experiment, we found that pecking rates peaked at intermediate flock sizes (three to six individuals), which was influenced by greater availability of foraging time and more aggressive interactions in large groups. In the second experiment, flock sizes in the patches with food increased with population size likely due to the benefits of patch exploitation in groups. Flock size decreased after predator attack probably because refuge availability reduced perceived predation risk more than flocking in larger groups. Food abundance had minor effects, varying flock sizes between the two patches with food, under high food availability conditions when population size was high, probably due to social cohesion effects. Our results suggest that: (1) this species has an inverted-U food intake‐group size relationship with a range of intakemaximizing flock sizes rather than a single peak, (2) the presence of a near refuge modifies the expected benefits of group patch exploitation under high predation risk, and (3) an increase in population size would more likely be translated into rapid increases in the size of the flocks rather than in more new flocks.

Colonial seabirds such as alcids often do not rapidly recolonize former breeding habitat following extirpation of nesting colonies. Social attraction (e.g., use of decoys, recorded vocalizations and mirrors) artificially stimulates nesting by providing social cues that encourage colonization. Common Murres (Uria aalge) stopped breeding at Devil’s Slide Rock, San Mateo County, California following the 1986 Apex Houston oil spill. Natural recolonization did not occur between 1987 and 1995. Common Murres began regular visits to Devil’s Slide Rock within 24 hours of social attraction equipment installation in January 1996 and six pairs nested by June 1996. Over 90% of murre observations were in decoy plots in contrast to control plots and outside of plots where few murre observations occurred. Significantly more murre presences versus absences were recorded in low density decoy plots and these birds most often frequented open areas (aisles) within decoy clusters. Significantly larger groups of murres...

International audience; The fruit fly Drosophila melanogaster has emerged as a model organism for research on social interactions. Although recent studies have described how individuals interact on foods for nutrition and reproduction, the complex dynamics by which groups initially develop and disperse have received little attention. Here we investigated the dynamics of collective foraging decisions by D. melanogaster and their variation with group size and composition. Groups of adults and larvae facing a choice between two identical, nutritionally balanced food patches distributed themselves asymmetrically, thereby exploiting one patch more than the other. The speed of the collective decisions increased with group size, as a result of flies joining foods faster. However, smaller groups exhibited more pronounced distribution asymmetries than larger ones. Using computer simulations, we show how these non-linear phenomena can emerge from social attraction towards occupied food patches, whose effects add up or compete depending on group size. Our results open new opportunities for exploring complex dynamics of nutrient selection in simple and genetically tractable groups.

Use of cover objects for hiding is a well developed behavior in reptiles, including snakes. Snakes sometimes aggregate under cover objects, which may reflect a shortage of suitable cover, very favorable conditions, social attraction, or simply chance. However, most studies of aggregation behavior have been conducted in the laboratory. In this study, I investigated the tendency of six species of snakes to aggregate under rocks in the field in southern Ontario, Canada. Most snakes under rocks were by themselves, but I found single- and mixed-species aggregations of up to four snakes. Although all species were involved in mixed-species aggregations, I did not find all possible combinations of species; no aggregations involved more than two species. Goodness-of-fit tests suggested that the pattern of aggregation sizes was well described by a geometric distribution, implying a nonrandom tendency toward aggregation. Nonetheless, because data were pooled over time, random occurrence of aggregation cannot be rule...

Past research with common chimpanzees, Pan troglodytes, and cross-cultural data with human beings suggest that relative to females, males prefer group over individual interaction. The present study tested whether this sex difference would be found in 6–8-month-old human infants using a preferential looking paradigm. Results showed that relative to females, males looked more at the group versus the individual stimuli. The results are consistent with an evolutionary mechanism that produced sex differences in the organization of relationships in human society.

Availability and use of public information and conspecific density for settlement decisions in the collared flycatcher

Individuals at the leading edge of a biological invasion constantly encounter novel environments. These pioneers may benefit from increased social attraction, because low population densities reduce competition and risks of pathogen transfer, and increase benefits of information transfer. In standardized trials, cane toads ( Rhinella marina ) from invasion-front populations approached conspecifics more often, and spent more time close to them, than did conspecifics from high-density, long-colonized populations.

Diversity of animal personalities has been proposed to arise from differences in social attraction, and to enhance behavioural flexibility of a population. The present study evaluated gregariousness as a personality trait in 14 ewes kept on pasture. Gregariousness was defined based on the frequency of having a close neighbour (3m). Highly gregarious (HG) and less gregarious (LG) animals were separated into two groups (n=7) which were reintegrated after 18 days. During direct field observations, behaviour was recorded individually every 15 min. Each session lasted 2.5h (08.30-11.00 h or 14.30-17.00 h, respectively). Behavioural synchronization was highest when the group consisted only of HG individuals (κHG=0.69, κLG=0.31; t=5.29; p0.001), indicating that gregariousness predicted behavioural synchronization in sheep. Though sheep are generally recognized as a highly gregarious species, HG and LG individuals could be differentiated clearly and consistently. Research on animal personality might help explain social influences on behavioural synchronization.

Larval and adult fruit flies are attracted to volatiles emanating from food substrates that have been occupied by larvae. We tested whether such volatiles are emitted by the larval gut bacteria by conducting tests under bacteria-free (axenic) conditions. We also tested attraction to two bacteria species, Lactobacillus brevis, which we cultured from larvae in our lab, and L. plantarum, a common constituent of fruit flies' microbiome in other laboratory populations and in wild fruit flies. Neither larvae nor adults showed attraction to axenic food that had been occupied by axenic larvae, but both showed the previously reported attraction to standard food that had been occupied by larvae with an intact microbiome. Larvae also showed significant attraction to volatiles from axenic food and larvae to which we added only either L. brevis or L. plantarum, and volatiles from L. brevis reared on its optimal growth medium. Controlled learning experiments indicated that larvae experienced with both standard and axenic used food do not perceive either as superior, while focal larvae experienced with simulated used food, which contains burrows, perceive it as superior to unused food. Our results suggest that flies rely on microbiome-derived volatiles for long-distance attraction to suitable food patches. Under natural settings, fruits often contain harmful fungi and bacteria, and both L. brevis and L. plantarum produce compounds that suppress the growth of some antagonistic fungi and bacteria. The larval microbiome volatiles may therefore lead prospective fruit flies towards substrates with a hospitable microbial environment.

SUMMARY: The sensory basis of the behavior of cuttlefish towards basket traps explains in part the mechanism of capture by the gear. Previous studies have shown that the reaction of cuttlefish Sepia esculenta to basket traps is mediated mainly by vision. In this study, visual factors that attract cuttlefish to basket traps were examined in the laboratory. The reaction of cuttlefish was divided into three processes of recognition, approach, and entry; the frequency and the duration of each process indicated the strength of the reaction. Cuttlefish were most attracted to a basket trap that contrasted most strongly with the background. When the dismantled components of the basket trap were presented as visual targets to cuttlefish, all the components were approached by the cuttlefish, which remained in the internal space. Cuttlefish have a habit of occupying the internal space of a structure and this habit seems to be the main motivation for entry into a trap. Another experiment was carried out to examine the social attraction between individuals inside and outside a trap. Social interference between males and females seems to be part of the mechanism of capture of cuttlefish by basket traps.

Differences in the exploratory behavior and social tendencies of 29 guppies (Poecilia reticulata) in 2 domains of situations involving novelty and conspecincs were investigated. Consistent individual differences were found in most behavior patterns. Two behavioral dimensions (Activity Exploration and Fear Avoidance) were identified in the novelty situations. Likewise, 2 dimensions (Sociability and Locomotion) were found in the social situations. An analysis of relationships between these 2 test domains revealed the existence of even broader behavioral dimensions (Approach, governing exploration and social attraction, and Fear Avoidance, governing responses to aversive stimulation). Thus, it was shown that "personality" may represent an important behavioral category in the guppy provided it is defined precisely and objectively.

Summary We investigated whether adult fruit flies (Drosophila melanogaster) use cues of larvae as social information in their food patch choice decisions. Adult male and female fruit flies showed attraction to odours emanating from foraging larvae, and females preferred to lay eggs on food patches occupied by larvae over similar unoccupied patches. Females learned and subsequently preferred to lay eggs at patches with novel flavours previously associated with feeding larvae over patches with novel flavours previously associated with no larvae. However, when we controlled for the duration of exposure to each flavoured patch, females no longer preferred the flavour previously associated with feeding larvae. This suggests that social learning in this context is indirect, due to strong social attraction biasing experience.

Socio-ecological models combine environmental and social factors to explain the formation of animal groups. In anurans, tadpole aggregations have been reported in numerous species, but the factors driving this behaviour remain unclear. We conducted controlled choice experiments in the lab to determine whether green and golden bell frog (Litoria aurea) tadpoles are directly attracted to conspecifics (social factors) in the absence of environmental cues. Using repeated measures, we found that individual tadpoles strongly preferred associating with conspecifics compared to being alone. Furthermore, this preference was body size dependent, and associating tadpoles were significantly smaller than non-associating tadpoles. We suggest that small tadpoles are more vulnerable to predation and therefore more likely to form aggregations as an anti-predator behaviour. We demonstrate that tadpoles present an ideal model system for investigating how social and ecological factors influence group formation in vertebrates.

Social relationships can have important fitness consequences, and how well an individual is socially connected often correlates with other behavioral traits. Whether such correlations are caused by underlying individual differences in social attraction usually remains unclear, because to identify effects of individual traits on social attraction, it is essential to experimentally exclude the influence of the social partner. Using standardized high-definition video playback on captive great tits (Parus major), we effectively demonstrate the influence of individual traits on the motivation to be near a conspecific. We show that social attraction varied contrastingly with boldness and stimulus novelty. Shyer birds tended to show stronger social attraction when they were confronted with the stimulus bird for the first time. Lower ranked birds showed the overall strongest social attraction. This rank effect remained after experimentally changing dominance ranks by altering group compositions. Moreover, preference for social association tended to increase with a decrease in dominance rank, suggesting that birds plastically change their social preference in relation to their within-group dominance status. Our results provide insight into how social relations can form and change, processes that are key for understanding the long-term consequences of the social environment, and the role individuals might play in influencing this environment themselves.

We hypothesised that (i) increased feeding motivation will cause sheep to move further apart as a result of individuals trying to find food and (ii) in conditions of high food availability, sheep will move less and show greater social attraction. The effects of both feeding motivation and food availability on spatial distribution was examined in eight groups of food-deprived (high feeding motivation) and satiated (low feeding motivation) sheep in good or poor food resource plots in a 2 × 2 design. Distance travelled was assessed using Global Positioning System collars, grazing time using scan sampling and social cohesion using proximity collars that record the number and duration of encounters within 4 m. Food-deprived sheep in the good-resource plots grazed the most, whereas satiated sheep in the poor-resource plots grazed the least (P = 0.004). Food deprivation had no significant effect on the number or duration of encounters and feeding motivation appeared to have little effect on spatial distribution. Contrary to expectation, sheep had more encounters (P = 0.04) of a longer total duration (P = 0.02) in poor-resource plots than in good-resource plots, indicating that sheep were showing more social cohesion if food was scarce. Our findings suggest that when food is scarce, animals may come together in an attempt to share information on food availability. However, when a highly preferred food is abundant and well dispersed, they may move apart in order to maximise the intake. It is concluded that the particular details of our experiment, namely the even distribution or absence of a highly preferred food, affected spatial distribution patterns as sheep tried to find this food and maximise the intake.

The importance of social attraction in the formation of foraging groups was examined for a stream-dwelling cyprinid, the rosyside dace, Clinostomus funduloides . Dace arrivals and departures at natural foraging sites were monitored and tested for (1) tendency of dace to travel in groups, and (2) dependency of arrival and departure rates on group size. Dace usually entered and departed foraging sites independently of each other. Group size usually affected neither arrival rate nor departure probability. Thus, attraction among dace appeared weak; foraging groups most often resulted from dace aggregating in preferred foraging sites. The strongest evidence of social attraction was during autumn, when dace departure probability often decreased with increasing group size, possibly in response to increased threat of predation by a seasonally occurring predator. Dace also rarely avoided conspecifics, except when an aggressive individual defended a foraging site. Otherwise, there was little evidence of exploitative competition among dace for drifting prey or of foraging benefits in groups, because group size usually did not affect individual feeding rates. These results suggest that the benefits of group foraging demonstrated under laboratory conditions in other studies may not always apply to field conditions.

"In der wissenschaftlichen Diskussion zeigen sich zunehmend Tendenzen der Entkopplung des Prozesses der Partnerwahl von sozialen und kulturellen Bezügen. Das soziale Handeln der Akteure wird hierbei immer häufiger in zweiter Instanz naturalisiert und als evolutionäre Antwort auf die Notwendigkeit der genetischen Reproduktion interpretiert. Reproduktionserfolg wird damit zum alles bestimmenden Ausgangs- und Zielpunkt menschlichen Verhaltens. Gleichzeitig zeigt sich aber auch große (sozial)wissenschaftliche Skepsis und individuelles Unbehagen angesichts der Vorstellung, Menschen im Prozess der Partnerwahl in letzter Konsequenz auf die Exekution genetischer Verhaltensprogramme zu reduzieren. Partnerwahl weist aus einer soziologischen Perspektive immer auch Aspekte individueller Zuschreibung und Einflussnahme auf und ist prinzipiell Prozessen der sozialen und kulturellen Formung zugänglich. Der Vortrag bewegt sich im Spannungsfeld der gegenwärtig aktuellen Kontroverse um die soziale bzw. biologische Determinierung von Partnerwahl und Liebe. Er ist hierbei gleichermaßen empirischen Erkenntnissen aus Soziobiologie, evolutionärer Psychologie und Soziologie, wie theoretischen Überlegungen aus einer sozialkonstruktivistischen Perspektive verpflichtet. Ziel der Präsentation ist es, im Hinblick auf die Modi der Partnerwahl die oftmals antagonistisch verwendeten Argumente von Evolutionsbiologie und Sozialforschung kritisch aufzuarbeiten. Hierbei soll aufgezeigt werden, dass gegenwärtig nicht nur Tendenzen der Re-Naturalisierung von Partnerwahl zu verzeichnen sind, sondern mithin auch gegenläufige Prozesse, etwa die kulturelle Aufwertung von Partnerschaft qua medialer Inszenierung, vermehrte Steuerungsversuche im Hinblick auf die physische und soziale Attraktivität auf dem Partnermarkt (Mode, Fitnessbewegung Schönheitschirurgie, Partnerschaftsratgeber). Kritisch soll auch gefragt werden, ob gegenwärtige Charakteristika der Sozialstruktur tatsächlich in den Leitgedanken des 'survival of the fittest' passen und ob die ausdifferenzierte Symbolkommunikation im Prozess der Partnerschaftsanbahnung tatsächlich angemessen evolutionsbiologisch erklärbar ist." (Autorenreferat)

Inter-individual distances (IIDs), during open-field tests, were measured in single sex pairs of quail of lines divergently selected for high (HSR) or low (LSR) levels of social reinstatement (SR) behaviour. Tests were carried out when the chicks were 1-, 3- and 6-weeks of age. IIDs were established within 1 min and remained stable thereafter. In HSR and mixed line pairs, but not LSR line pairs, IIDs increased with age. IIDs were shorter in HSR line pairs than in LSR or mixed line pairs at 1- and 3-weeks of age but not at 6-weeks of age when IIDs were similar in all pair-types. At 1- and 3-weeks of age, IIDs in mixed line pairs were intermediate to those in HSR and LSR line pairs. The sex of the pair-members did not influence IIDs. Previous studies have shown that selection for SR behaviour, in quail chicks, has effects that persist into later life and influence characters not present in the birds' behavioural repertoire at the time of testing for the purposes of selection. Such behaviour patterns include aggression, sexual behaviour and socio-sexual proximity behaviour. All of these behaviour patterns are expressed at higher levels in HSR line birds than LSR line birds. Differences in IIDs between HSR and LSR line birds may, therefore, be due to an interaction between environmental and genetic effects. In young HSR chicks, social reinstatement is the primary motivation and IIDs are short. However, as the HSR line chicks' age, IIDs reflect an interaction between social attraction and aggression related avoidance behaviour that tends to increase IIDs. In LSR line chicks aggression and social motivation are low at all ages and IIDs tend to remain stable.

We investigated the behavioural mechanisms involved in group formation at a feeding site in a captive snowshoe hare population. The analysis showed that grouping resulted most often from a feeding attraction which led individuals to use the feeding site independently of each other. However social attraction and especially social repulsion among hares were also involved in group size dynamics. As group size increased, social repulsion underlined by an autocatalytic process led the hares to collectively leave the feeding site. Consequently, the social interactions rates and distance covered per hare increased non-linearly with hare number present at the feeding site. The results suggest that hare behaviour underlined by these mechanisms may influence the risks of starvation and predation. From these results, further field studies are suggested to test in the framework of a multi-factor hypothesis how hare behaviour, food supply and predation may interact simultaneously in population regulation.

Individuals foraging in groups can use two different tactics for obtaining food resources. Individuals can either search for food sources themselves (producing) or they can join food discoveries of others (scrounging). In this study we use a genetic algorithm in a spatially explicit producer-scrounger game to explore how individuals compromise between exploration (an important axis of animal personality) and scrounging and how characteristics of the environment affect this compromise. Agents varied in exploration and scrounging and a genetic algorithm searched for the optimal combination of exploration and scrounging. The foraging environments featured different levels of patch richness, predation and patch density. Our simulations show that under conditions of low patch densities slow exploring scroungers were favored whereas high patch density favored fast exploring individuals that either produced (at low patch richness) or scrounged (at high patch richness). In high predation environments fast exploring individuals were selected for but only at low to intermediate patch densities. Predation did not affect scrounging behavior. We did not find a divergence of exploration 'types' within a given environment, but there was a general association between exploration and scrounging across different environments: high rates of scrounging were observed over nearly the full spectrum of exploration values, whereas high rates of producing were only observed at high exploration values, suggesting that cases in which slow explorers start producing should be rare. Our results indicate that the spatial arrangement of food resources can affect the optimal social attraction rules between agents, the optimality of foraging tactic and the interaction between both.

The effect of social context on experimental foraging in squirrel monkeys (Saimiri sciureus) was investigated. The 12 subjects comprised six pairs in which strong social preference and attraction had been demonstrated during observations of a stable group. Individuals were first trained to discriminate spatially separated rich and poor foraging bins containing 75% and 25% of the food items, respectively, with their partners restrained equidistant from the two bins. The monkeys invested an average of 75.5% of their foraging time in the rich bin. Each individual was then tested with its partner restrained in different locations relative to the bins to determine the effect of partner proximity on foraging patterns. Foraging efficiency at the start of a session was enhanced when the partner was restrained adjacent to the rich bin compared to restraint away from this bin. Over an entire foraging session, however, all conditions providing partner accessibility were similar in yielding enhanced foraging efficiency compared to partner absence. Little time was spent in close physical proximity to the partner under any condition. It is suggested that accessibility of the social partner, rather than close physical proximity, has an important influence on the foraging squirrel monkey. © 1995 Wiley-Liss, Inc.

Animals often settle near competitors, a behavior known as social attraction, which belies standard habitat selection theory. Two hypotheses account for these observations: individuals obtain Allee benefits mediated by the physical presence of a competitor, or they use successfully settled individual as a source of information indicating the location of high quality habitat. We evaluated these hypotheses experimentally in two species of shrikes. These passerine birds with a raptor-like mode of life impale prey to create larders that serve as an indicator of male/habitat quality. Thus, two forms of indirect information are available in our system: a successfully settled shrike and its larder. Typically these two cues are associated with each other, however, our experimental treatment created an unnatural situation by disassociating them. We manipulated the presence of larders of great grey shrikes and examined the settling decisions of red-backed shrikes within and outside the great grey shrike territories. Male red-backed shrikes did not settle sooner on plots with great grey shrikes compared to plots that only contained artificial larders indicating that red-backed shrikes do not use the physical presence of a great grey shrike when making settling decisions which is inconsistent with the Allee effect hypothesis. In contrast, for all plots without great grey shrikes, red-backed shrikes settled, paired and laid clutches sooner on plots with larders compared to plots without larders. We conclude that red-backed shrikes use larders of great grey shrikes as a cue to rapidly assess habitat quality.

Five types of reindeer populations are distinguished in terms of population dynamics, population density, social structure and migration distance. Differences in the biological rhythms of the populations result in calving occuring 20 days before snow melting in all populations as well as maximal utilization by the deer of young green vegetation in summer. The growth of antlers may serve as a regulatior of biological rhytms. Populations differ in the level of social motivation. Formation of groups of not less than 30-35 animals ensures cooperative protection from insects and management of the group by man. The fidelity to the calving sites, summer ranges and constant migration routes is based on the common orientation reactions of the animals and social attraction. The direction and migration routes are detemined by obligate learning. The dynamics of populations depends on the fertility of 2 and 3 year old females which is determined by feeding conditions in summer and the activity of males during the rut. Migration plays an important role in the population dynamics.

The structure of social attraction was assessed in pair- and group-living squirrel monkeys (Saimiri) using paired-comparison and single-stimulus preference tests. Effects of the social environment were most prominent in females. Females housed with a single male showed sharply increased attraction to like-sex strangers and less pronounced increase in attraction to opposite-sex strangers, as compared to group-living females. Differences between pair- and group-living males were in the same direction found with females, but less extreme. Most group-living monkeys strongly preferred familiar animals to strangers regardless of sex, and like-sex to opposite-sex familiars. Change in the structure of social attractions in response to variations in the composition of the social environment appears to be an important factor in the maintenance of the species-typical grouping pattern in the squirrel monkey.

1. The influences of social, spatial and population density parameters on agonistic behavior in the adult male wolf spider Schizocosa crassipes were analyzed. Social density varied the number of spiders present (N = 2, 3 or 5) in different spatial densities (U =90, 180, 270 or 450 cm 2 ). Population density varied the amount of space available per animal, irrespective of social and spatial density. 2. Multiple stepwise discriminant analysis revealed differences among the social, spatial and population density groups on the basis of the number and kinds of agonistic behaviors displayed. 3. As social density increased, the number of agonistic interactions increased. Although the spiders did not interact more frequently with any one partner over 10 days, they continued to respond differentially to one another with regard to established dominance-subordinance relations. 4. Within each spatial density, the amount of space had no effect on the total number of agonistic interactions. However, within each social density, the number of agonistic interactions varied according to the amount of space available. In less restricted spatial densities, agonistic interactions increased with the number of spiders. 5. The absolute distance maintained between spiders increased proportionally with spatial density. However, when distances were expressed as a percentage of the maximum possible distance between any two animals, spiders tested in the largest spatial density exhibited decreasing inter-individual distances over time, while those tested in the smallest spatial density exhibited increasing distances. These findings suggested social attraction among the spiders when sufficient space was available. 6. As population density increased the number of agonistic interactions increased. However, no differences in the number of interactions between specific partners occurred. 7. By comparing Equal and Low population density groups, an estimate of the personal space of male S. crassipes was calculated to be 5.35 cm, which agreed with field and laboratory observations. 8. When spiders are grouped within certain spatial limits, various types of agonistic behaviors serve to space the animals according to their personal distance. High population density may interfere with communicatory behavior patterns which in turn may weaken dominance-subordinance relationships.

Members of two subspecies of deer mouse (Peromyscus maniculatus) that differ in social gregariousness were given septal lesions and tested for pairwise sociability. Gracilis normally a highly social animal, became even more gregarious following septal damage, while bairdi, which normally shows avoidance of social contact, showed further reductions in sociability. The findings lend no support to a previous suggestion that septal lesions enhance sociability generally across species; instead, they suggest that reported increases in social contact in lesioned animals are a secondary consequence of the lesion’s tendency to enhance predominant behavior patterns.

The strength and specificity of attraction between male and female cagemates was compared in Saimiri and Callicebus, using paired-comparison and single-stimulus methods of testing. Results from both methods showed that the attraction to the cagemate was stronger and more specific in Callicebus than in Saimiri. Sex differences were more pronounced in Saimiri than in Callicebus. Squirrel monkey females were more strongly attracted to strangers than were males and they clearly preferred female strangers over male strangers or their male cagemates.