scholarly journals Effect of group size and reproductive status on faecal glucocorticoid concentration and vigilance in a free-ranging population of Przewalski’s gazelle

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Ruoshuang Liu ◽  
Jianbin Shi ◽  
Dingzhen Liu ◽  
Shikui Dong ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Group Size ◽  
Group Living ◽  
Reproductive Status ◽  
Qinghai Lake ◽  
Management Measures ◽  
Antipredator Responses ◽  
Individual Survival ◽  
High Level ◽  
Free Ranging ◽  
Procapra Przewalskii

Abstract Elevated glucocorticoid (GC) concentration and increased vigilance are two common responses to predation risk in mammals. Chronic high-level GC concentration and vigilance occur at the expense of other life maintenance and reproduction activities, reflecting a trade-off between individual survival and future fecundity. Przewalski’s gazelle (Procapra przewalskii) is a group-living ungulate endemic to the high-altitude Qinghai Lake region of China. Group-size effect on gazelle vigilance has been examined, yet little is known about how their GC concentration is affected by group size or reproductive status. In this study, we examined the effect of group size and reproductive status on faecal glucocorticoid metabolite (FGM) concentrations and individual vigilance during different stages of the reproduction cycle (i.e. non-breeding, lambing and rutting) in free-ranging adult female Przewalski’s gazelles. Group size did not influence FGMs significantly, but mean vigilance duration increased with group size. The gazelles’ FGMs and vigilance peaked in lambing season. FGMs showed no difference between rutting season and non-reproductive season, but vigilance was lowest in the rutting season. FGMs correlated with vigilance frequency and vigilance duration. Antipredator responses of female Przewalski’s gazelles appear to change with reproductive status but not with group size in free-ranging females. Management measures should be taken in the lambing season to minimize stress on mother gazelles.

Bearded saki socioecology: affiliative male–male interactions in large, free-ranging primate groups in Suriname

Behaviour ◽  
2014 ◽  
Vol 151 (4) ◽  
pp. 493-533 ◽  
Author(s):  
Tremaine Gregory ◽  
Marilyn A. Norconk
Keyword(s):  
Group Size ◽  
Group Living ◽  
Wet Season ◽  
Social Patterns ◽  
Continuous Forest ◽  
Chiropotes Sagulatus ◽  
Free Ranging ◽  
Bearded Sakis ◽  
First Time ◽  
Large Groups

Bearded sakis (Chiropotes spp.) are among the least known primates in the world, particularly with regard to their social organization. However, extremely large and variable group size and growing evidence for affiliative relationships among males, make them a fascinating subject for studies of male–male tolerance and the evolution of large groups. During a 13-month study of free ranging Guianan bearded sakis (Chiropotes sagulatus) in continuous forest in Suriname, we documented variation in group size seasonally and social behaviour, particularly among males. We found that group size was smaller and more variable in the long dry season than the short wet season, perhaps in response to changes in resource availability. We found clear evidence of affiliative male–male relationships, with males being more social than females (89.2% of events involved one male versus 15.6% that involved one female) and typically socializing with other males (68.7% of events involved 2 or more males). We also found no evidence of hierarchical relationships between males (complete absence of agonistic interactions), and we documented unique male-affiliative behaviours and temporary all-male subgroups for the first time. To investigate potential explanations of male tolerance, we compared bearded saki social patterns to other multi-male group living primates (Ateline and Pan spp.). We found similarities with Brachyteles that suggest high intergroup mating competition and scramble competition for mates within groups.

Vigilance and Grouping in the Eastern Gray Kangaroo, Macropus giganteus

1993 ◽  
Vol 41 (4) ◽  
pp. 325 ◽  
Author(s):  
AML Colagross ◽  
A Cockburn
Keyword(s):  
Group Size ◽  
Edge Effect ◽  
Group Formation ◽  
Reproductive Status ◽  
Risk Of Predation ◽  
Vigilance Behaviour ◽  
Reproductive Females ◽  
Group Sex ◽  
Free Ranging ◽  
Number Of Individuals

Group formation may help animals reduce their risk of predation and allow more time for activities other than vigilance against predators. Eastern grey kangaroos, Macropus giganteus, are gregarious and form open-membership groups. Vigilance behaviour of free-ranging kangaroos was observed in relation-to number of individuals within the group, sex and reproductive status of individuals, proximity to cover and position within the group. Our data support the view that kangaroos adjust their behaviour in relation to the risk of predation. Reproductive females, individuals on the periphery of the group and individuals in groups far from cover were most vigilant. Contrary to previous reports, vigilance behaviour was not influenced by group size except through the edge effect-the tendency of the proportion of individuals on the periphery of the group to decline as group size increases.

scholarly journals Variable fledging age according to group size: trade-offs in a cooperatively breeding bird

2007 ◽  
Vol 3 (6) ◽  
pp. 624-627 ◽  
Author(s):  
N.J Raihani ◽  
A.R Ridley
Keyword(s):  
Group Size ◽  
Group Living ◽  
Breeding Bird ◽  
Communal Roost ◽  
Trade Offs ◽  
Efficient Detection ◽  
Risk Of Predation ◽  
Cooperatively Breeding ◽  
Individual Survival ◽  
Dilution Effects

Group living can provide individuals with several benefits, including cooperative vigilance and lower predation rates. Individuals in larger groups may be less vulnerable to predation due to dilution effects, efficient detection or greater ability to repel predators. Individuals in smaller groups may consequently employ alternative behavioural tactics to compensate for their greater vulnerability to predators. Here, we describe how pied babbler ( Turdoides bicolor ) fledging age varies with group size and the associated risk of nestling predation. Nestling predation is highest in smaller groups, but there is no effect of group size on fledgling predation. Consequently, small groups fledge young earlier, thereby reducing the risk of predation. However, there is a cost to this behaviour as younger fledglings are less mobile than older fledglings: they move shorter distances and are less likely to successfully reach the communal roost tree. The optimal age to fledge young appears to depend on the trade-off between reduced nestling predation and increased fledgling mobility. We suggest that such trade-offs may be common in species where group size critically affects individual survival and reproductive success.

Subjective Fear Dilutes as Group Size Increases

2020 ◽  
Author(s):  
dean mobbs ◽  
Ellen Tedeschi ◽  
Anastasia Buyalskaya ◽  
Brian Silston
Keyword(s):  
Group Size ◽  
Real World ◽  
Survival Benefit ◽  
Group Living ◽  
External Factors ◽  
Threat Perception ◽  
Perception Of Threat ◽  
Threat Level ◽  
Internal States ◽  
Risk Dilution

According to Hamilton’s Selfish Herd Theory, a crucial survival benefit of group living is that it provides a ‘risk dilution’ function against predation. Despite a large literature on group living benefits in animals, few studies have been conducted on how group size alters subjective fear or threat perception in humans, and on what factors drive preferences for being in groups when facing threats. We conducted seven experiments (N=3,838) to test (A) if the presence of others decreases perception of threat under a variety of conditions. In studies 1 to 3, we experimentally manipulated group size in hypothetical and real-world situations, to show that fear responses decreased as group size increased. In studies 4 to 7 we again used a combination of hypothetical, virtual and real-world decisions to test (B) how internal states (e.g. anxiety) and external factors (e.g. threat level, availability of help) affected participants’ preference for groups. Participants consistently chose larger groups when threat and anxiety were high. Overall, our findings show that group size provides a salient signal of protection and safety.

Effects of a group-living experience on the antipredator responses of individual tadpoles

2021 ◽  
Vol 180 ◽  
pp. 93-99
Author(s):  
Bianca Guadin ◽  
Andrea Gazzola ◽  
Alessandro Balestrieri ◽  
Giovanni Scribano ◽  
José Martín ◽  
...  
Keyword(s):  
Group Living ◽  
Antipredator Responses

scholarly journals Fitness of breeders in social Damaraland mole-rats is independent of group size

2021 ◽  
Author(s):  
Jack Thorley ◽  
Hanna Bensch ◽  
Kyle Finn ◽  
Tim Clutton-Brock ◽  
Markus Zöttl
Keyword(s):  
Reproductive Success ◽  
Group Size ◽  
Survival Rates ◽  
Group Living ◽  
Adult Survival ◽  
High Survival ◽  
Successful Reproduction ◽  
Related Group ◽  
Group Members ◽  
Using Data

Damaraland mole-rats (Fukomys damarensis) are usually viewed as an obligatorily group living eusocial species in which successful reproduction is dependent on reproductive altruism of closely related group members. However, the reproductive ecology of social mole-rats in their natural environment remains poorly understood and it is unclear to what extent successful reproduction is dependent on assistance from other group members. Using data from a 7-year field study of marked individuals, we show that, after dispersal from their natal group, individuals typically settled alone in new burrow systems where they enjoyed high survival rates, and often remained in good body condition for several years before finding a mate. Unlike most other eusocial or singular cooperative breeders, we found that Damaraland mole-rats reproduced successfully in pairs without helpers and experimentally formed pairs had the same reproductive success as larger established groups. Overall there was only a weak increase in reproductive success with increasing group size and no effect of group size on adult survival rates across the population. Juveniles in large groups grew faster early in life but their growth rates declined subsequently so that they eventually plateaued at a lower maximum body mass than juveniles from small groups. Taken together, our data suggest that the fitness benefits of group living to breeders are small and we suggest that extended philopatry in Damaraland mole-rats has evolved because of the high costs and constraints of dispersal rather than because of strong indirect benefits accrued through cooperative behaviour.

scholarly journals Capacity of countries to reduce biological invasions

2021 ◽  
Author(s):  
Guillaume Latombe ◽  
Hanno Seebens ◽  
Bernd Lenzner ◽  
Franck Courchamp ◽  
Stefan Dullinger ◽  
...  
Keyword(s):  
Biological Invasions ◽  
Alien Species ◽  
Economic Space ◽  
Country Level ◽  
Management Measures ◽  
Ecological Predictors ◽  
Global Environmental ◽  
Education Innovation ◽  
Taxonomic Groups ◽  
High Level

AbstractThe extent and impacts of biological invasions on biodiversity are largely shaped by an array of socio-ecological predictors, which exhibit high variation among countries. Yet a global synthetic perspective of how these factors vary across countries is currently lacking. Here, we investigate how a set of five socio-ecological predictors (Governance, Trade, Environmental Performance, Lifestyle and Education, Innovation) explain i) country-level established alien species (EAS) richness of eight taxonomic groups, and ii) country capacity to prevent and manage biological invasions and their impacts. Trade and Governance together best predicted the average EAS richness, increasing variance explained by up to 54% compared to models based on climatic and spatial variables only. Country-level EAS richness increased strongly with Trade, whereas high level of Governance resulted in lower EAS richness. Historical (1996) levels of Governance and Trade better explained response variables than current (2015) levels. Thus, our results reveal a historical legacy of these two predictors with profound implications for the future of biological invasions. We therefore used Governance and Trade to define a two-dimensional socio-economic space in which the position of a country captures its capacity to address issues of biological invasions. Our results provide novel insights into the complex relationship between socio-ecological predictors and biological invasions. Further, we highlight the need for designing better policies and management measures for alien species, and for integrating biological invasions in global environmental scenarios.

scholarly journals Proximity-based vocal networks reveal social relationships in the Southern white rhinoceros

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Julia Jenikejew ◽  
Brenda Chaignon ◽  
Sabrina Linn ◽  
Marina Scheumann
Keyword(s):  
Social Interactions ◽  
Communication Networks ◽  
Social Relationships ◽  
Social Behaviour ◽  
Vocal Communication ◽  
Group Living ◽  
White Rhinoceros ◽  
Southern White Rhinoceros ◽  
Social Associations ◽  
High Level

Abstract Vocal communication networks can be linked to social behaviour, allowing a deeper understanding of social relationships among individuals. For this purpose, the description of vocal dyads is fundamental. In group-living species, this identification is based on behavioural indicators which require a high level of reactivity during social interactions. In the present study, we alternatively established a proximity-based approach to investigate whether sex-specific differences in vocal communication reflect social behaviour in a species with rather loose social associations and low levels of reactivity: the Southern white rhinoceros (Ceratotherium simum simum). We performed audio- and video recordings of 30 captive animals from seven groups. Vocal networks for the four most common call types were constructed by considering conspecifics at close distance (≤ 1 body length) to the sender as potential receivers. The analysis of the resulting unidirectional structures showed that not only the sex of the sender but also the sex of the potential receiver, the quality of social interactions (affiliative or agonistic) as well as association strength predict the intensity of vocal interactions between group members. Thus, a proximity-based approach can be used to construct vocal networks providing information about the social relationships of conspecifics—even in species with loose social associations where behavioural indicators are limited.

The effects of age, sex, reproductive status and temporal factors on the time-use of free-ranging red kangaroos

1993 ◽  
Vol 20 (6) ◽  
pp. 785 ◽  
Author(s):  
DM Watson ◽  
TJ Dawson
Keyword(s):  
Body Size ◽  
Group Size ◽  
Time Use ◽  
New South ◽  
New South Wales ◽  
Time Of Day ◽  
Adult Males ◽  
South Wales ◽  
Free Ranging ◽  
Foraging Time

The effects of temporal (time of day and season) factors and size, sex, female reproductive state and group size on the diel time-use of free-ranging red kangaroos (Macropus rufus) was examined. Particular emphasis was given to the effects on their foraging behaviour, with foraging divided into cropping, chewing and searching components. The study was conducted in semi-arid western New South Wales from July 1991 to March 1992, a time of deepening drought conditions in New South Wales. Group size had very little influence on the time-use of M. rufus. It was negatively but only weakly correlated with the proportion of foraging time spent chewing (chewing intensity). No significant differences in time-use were found between size classes of adult males (large and medium-sized males), females with or without pouch young, or females with different-sized pouch young (no visible young, small pouch young or large pouch young). Differences occurred between adult males, adult females and subadult kangaroos. These differences were mainly associated with their chewing and searching behaviour and were related to body size; as body size increased the proportion of time spent chewing and the intensity of chewing increased while the proportion of time searching and the proportion of foraging time spent searching (searching intensity) decreased. Neither the proportion of time spent cropping or foraging nor the proportion of foraging time spent cropping (cropping intensity) or the proportion of active time spent foraging (foraging intensity) differed between any size/sex/reproductive class. Temporal effects had a considerable influence on time-use. M. rufus were most active at night and in the few hours after sunrise and sunset. Seasonal changes in time-use were largely a result of changes in daytime behaviour. M. rufus foraged less and rested more during the day in winter than in spring or summer. There was no increase in the intensity or proportion of time spent foraging or cropping at night to compensate for the reduction in diurnal foraging. It is hypothesised that temporal variations in time-use were related to variations in weather and vegetation conditions.

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