Male group members are costly to plurally breeding Octodon degus females

Behaviour ◽  
2019 ◽  
Vol 156 (1) ◽  
pp. 1-36 ◽  
Author(s):  
Loren D. Hayes ◽  
Loreto A. Correa ◽  
Sebastian Abades ◽  
Cuilan L. Gao ◽  
Luis A. Ebensperger
Keyword(s):  
Litter Size ◽  
Adult Males ◽  
Octodon Degus ◽  
Direct Fitness ◽  
Soil Hardness ◽  
Standardize Variance ◽  
Group Variation ◽  
Group Members ◽  
Per Capita ◽  
Plural Breeding

Abstract We report the results of a 6-year study of social (number of adult males/females, relatedness of females, communal litter size) and ecological (mean/CV of food abundance, soil hardness, burrow openings) factors influencing the direct fitness of plurally breeding degu (Octodon degus) females. The best fit models for per capita offspring weaned and standardized variance in direct fitness (within-group variation) included the number of adult males per group. Per capita number of offspring weaned decreased and standardized variance in direct fitness increased with increasing number of adult males per group. Thus, females experience a cost associated with males that is not shared equally. Standardize variance in direct fitness decreased with increasing communal litter size. All other factors were not significant predictors of direct fitness variation. Our study suggests that plural breeding may not be as egalitarian as previously thought. Consequences of plural breeding may be influenced by intra- and inter-sexual conflict.

Bite force and jaw biomechanics in the subterranean rodent Talas tuco-tuco (Ctenomys talarum) (Caviomorpha: Octodontoidea)

2011 ◽  
Vol 89 (4) ◽  
pp. 334-342 ◽  
Author(s):  
Federico Becerra ◽  
Alejandra Echeverría ◽  
Aldo Iván Vassallo ◽  
Adrià Casinos
Keyword(s):  
Cross Section ◽  
Force Transducer ◽  
Bite Force ◽  
Adult Males ◽  
Subterranean Rodent ◽  
Soil Hardness ◽  
Ctenomys Talarum ◽  
Adductor Muscles ◽  
Typical Habitat

The Talas tuco-tuco ( Ctenomys talarum Thomas, 1898) is a South American subterranean rodent that digs using both forelimbs and incisors, the latter being used when animals face hard soils and fibrous roots. In this rodent, the incisors are also used during intermale competition for mates. Bite forces were measured on wild females (n = 21) and males (n = 21) (both adult and young individuals) using a force transducer. Bite force was significantly higher in adult males than in females (32 vs. 27 N, respectively). Bite forces calculated on the physiological cross-section of jaw adductor muscles in dissected specimens were slightly higher than in vivo measurements. Regressions against body mass showed that bite force scaled with positive allometry, with slopes of 0.89 (females) and 0.99 (males). No significant differences were observed, neither in the slope nor in the y intercept of both sexes’ equations; therefore intersexual differences in bite forces observed in adults should mainly be due to size dimorphism. Considering that soil hardness of C. talarum’s typical habitat averages 100 N/cm2, and taking into account incisor’s cross-section, it was assessed that the pressure exerted by jaw adductor muscles at the incisors level is three times higher than that required for soil penetration.

scholarly journals Neutering Effects on Social Behaviour of Urban Unowned Free-Roaming Domestic Cats

Animals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1105 ◽  
Author(s):  
Simona Cafazzo ◽  
Roberto Bonanni ◽  
Eugenia Natoli
Keyword(s):  
General Level ◽  
Territorial Behaviour ◽  
Adult Males ◽  
Domestic Cats ◽  
Obvious Effect ◽  
Focal Animal ◽  
The Hierarchical Structure ◽  
Group Members ◽  
Marking Behaviour ◽  
Free Ranging

The “trap, spay/neuter, and release” programs to manage unowned free-roaming cat populations are diffused worldwide and they are largely advised even in countries where the suppression of unowned cats is enforced by law. Despite the massive neutering campaigns in the world, there is little information on the influence of neutering on individual cat behaviour, as well as on the social structure of cat colonies. The aim of this study is to verify such effects. Before neutering, the group consisted of 17 free-roaming domestic cats, who were totally unrestrained. After neutering it consisted of 16 individuals. Data on the outcomes of aggressive, submissive, affiliative, and territorial behaviour were collected, using classic ethological methods (“focal animal”, “all occurrences”, and “1/0” sampling methods) (735 h of observation before and 537 h after neutering). The dominance hierarchy did not change after neutering. On the other hand, the frequency of aggressive, territorial behaviour as well as proximity among individuals decreased significantly. Affiliative behaviour has been observed among neutered adult males that never performed it before neutering. The results of this study suggest that, after neutering: (i) The group of free-ranging cats was stable over time; (ii) the hierarchical structure of the cat social group did not change; (iii) the general level of activity, decreased; (iv) urine spraying marking behaviour almost disappeared; (v) the level of social proximity among group members decreased, although it tended to increase in some male–male dyads. The most obvious effect of neutering, detected on individual behaviour, was that cats were less active.

scholarly journals Fight tactics in wood ants: individuals in smaller groups fight harder but die faster

2011 ◽  
Vol 278 (1722) ◽  
pp. 3243-3250 ◽  
Author(s):  
Tim P. Batchelor ◽  
Mark Briffa
Keyword(s):  
Group Size ◽  
Negative Influence ◽  
Resource Holding Potential ◽  
Attrition Rates ◽  
Formica Rufa ◽  
Wood Ants ◽  
Social Animals ◽  
Group Members ◽  
Per Capita ◽  
The Individual

When social animals engage in inter-group contests, the outcome is determined by group sizes and individual masses, which together determine group resource-holding potential (‘group RHP’). Individuals that perceive themselves as being in a group with high RHP may receive a motivational increase and increase their aggression levels. Alternatively, individuals in lower RHP groups may increase their aggression levels in an attempt to overcome the RHP deficit. We investigate how ‘group RHP’ influences agonistic tactics in red wood ants Formica rufa . Larger groups had higher total agonistic indices, but per capita agonistic indices were highest in the smallest groups, indicating that individuals in smaller groups fought harder. Agonistic indices were influenced by relative mean mass, focal group size, opponent group size and opponent group agonistic index. Focal group attrition rates decreased as focal group relative agonistic indices increased and there was a strong negative influence of relative mean mass. The highest focal attrition rates were received when opponent groups were numerically large and composed of large individuals. Thus, fight tactics in F. rufa seem to vary with both aspects of group RHP, group size and the individual attributes of group members, indicating that information on these are available to fighting ants.

The Hidden Costs of Sociality: Intra-Group Variation in Feeding Strategies in Sumatran Long-Tailed Macaques (Macaca Fascicularis)

Behaviour ◽  
1986 ◽  
Vol 99 (3-4) ◽  
pp. 296-314 ◽  
Author(s):  
Maria A. VAN NOORDWIJK ◽  
Carel P. VAN SCHAIK
Keyword(s):  
Body Size ◽  
Travel Time ◽  
Macaca Fascicularis ◽  
Fruit Trees ◽  
Feeding Competition ◽  
Feeding Strategies ◽  
Adult Males ◽  
Adult Females ◽  
Hidden Cost ◽  
Group Variation

AbstractGroups of long-tailed macaques (Macaca fascicularis) are often fissioned into a large main party and one or more small parties. We studied the size and composition of the main party in relation to fruit supply and the ecology of the various age-sex categories in order to establish the cause of this fissioning. The size of the main party varied not only because the size of available fruit trees varied but also because the various age-sex categories were so different in their feeding strategies that they sometimes went separate ways. Our observations suggest that body size and sex profoundly affected food requirements and the risks attached to leaving the main party. We concluded that adult females left the main party mainly to escape from feeding competition and attempted to reduce travel time when they had infants so as to minimise the costs of carrying infants. Males, by contrast, left above all because of their different food requirements; subadult males left to eat more fruit than the others, adult males mainly to eat bigger fruit than the others. This intra-group variation in feeding strategies constitutes a usually hidden cost to sociality.

scholarly journals Birth season glucocorticoids are related to the presence of infants in sifaka ( Propithecus verreauxi )

2009 ◽  
Vol 276 (1663) ◽  
pp. 1855-1863 ◽  
Author(s):  
Diane K. Brockman ◽  
Amy K. Cobden ◽  
Patricia L. Whitten
Keyword(s):  
Stress Responses ◽  
Physiological Stress ◽  
Ecological Factors ◽  
Adult Males ◽  
Birth Season ◽  
Propithecus Verreauxi ◽  
Group Stability ◽  
Dispersal Events ◽  
Free Ranging ◽  
Plural Breeding

The responses of plural breeding mammals to environmental stressors are little understood in free-ranging populations, but recent studies of singular breeders suggest that ecological factors and social milieu influence the variable physiological stress responses observed among individuals. Our previous studies examining faecal glucocorticoid (fGC)–behaviour interactions in plural breeding male sifaka ( Propithecus verreauxi ) show that fGC elevations coincide with specific dispersal events, particularly the eviction of subordinates by resident alpha males. This study examined the utility of fGC assays for assessing the stress responses of male sifaka to demographic changes in the population during the birth season. Analyses were based on 889 faecal samples collected over five birth seasons from 124 adult males residing in 55 different groups at Beza Mahafaly, Madagascar. Results show that fGC levels in males are unrelated to age, residence, group stability or rank, but are significantly and positively correlated with the presence of infants, annual elevations in weekly mean fGC concentrations in males paralleling increasing numbers of infants born annually in the population. These data are the first to show that in seasonal plural breeding species such as sifaka, elevated fGC in males reflects specific events related to reproduction rather than states or social context during the birth season.

Natural Disaster Risk and Collectivism

2017 ◽  
Vol 48 (8) ◽  
pp. 1263-1270 ◽  
Author(s):  
Shigehiro Oishi ◽  
Asuka Komiya
Keyword(s):  
Natural Disaster ◽  
Climatic Factors ◽  
Main Idea ◽  
Disaster Risk ◽  
Gdp Per Capita ◽  
Physical Environments ◽  
Pathogen Prevalence ◽  
Group Members ◽  
Per Capita ◽  
Natural Disaster Risk

Previous research found that low levels of national wealth and high levels of historical pathogen prevalence are associated with collectivism. The main idea is that harsh economic and physical environments present a psychological threat, which evokes collectivism or the priority of protecting in-group members. To the extent that natural disasters pose a major threat, we hypothesized that natural disaster risk is also associated with collectivism. Consistent with our hypothesis, nations with higher levels of natural disaster risk were more collectivistic than those with lower risk using both Hofstede’s individualism–collectivism scores and Taras, Steel, and Kirkman’s meta-analytic individualism–collectivism scores from 1970 to 2010, and Taras et al.’s meta-analytic individualism–collectivism scores from the 2000s. This association remained significant when controlling for other climatic factors such as historical pathogen prevalence, climatic harshness, and distance from the equator, respectively, when Hofstede’s individualism–collectivism scores and Taras et al.’s scores from 1970 to 2010 were used. The association became marginal when Taras et al.’s scores from the 2000s were used. A multiple regression analysis showed that natural disaster risk was not a predictor of collectivism, above and beyond gross domestic product (GDP) per capita, pathogen prevalence, climatic harshness, and distance from the equator simultaneously. Finally, we found the interaction between GDP per capita and natural disaster such that the link between natural disaster risk and collectivism was present among wealthy but not among poorer nations.

Function and Meaning of Wild Gorilla 'Close' Calls

Behaviour ◽  
1996 ◽  
Vol 133 (11-12) ◽  
pp. 827-845 ◽  
Author(s):  
A.H. Harcourt ◽  
K.J. Stewart
Keyword(s):  
Social Interactions ◽  
Adult Male ◽  
Dominance Rank ◽  
Adult Males ◽  
Social Significance ◽  
The Social ◽  
Future Activity ◽  
Close Call ◽  
Contact Calls ◽  
Group Members

We investigate the social significance of the within group ('close') calls of gorillas by examining correlates of calling with dominance rank and with relatedness of adults, and by examining whether the outcomes of interactions between adults differ depending on the calls given during the interactions. In two wild gorilla groups, the majority of adults give most of their calls when near another adult and fully in sight of them. Thus gorillas' use 'close' calls as more than mere contact calls. An adult gorilla's use of 'close' calls correlates with its own and with its partner's dominance rank, with effects being most obvious for the most dominant animals, the fully adult males. Thus the proportion of 'double grunts', the most common 'close' call, in an individual's repertoire correlated consistently with dominance rank; all non-silverback adults gave a higher percent of double grunts in the presence of subordinates than they did near dominant animals; individuals were most likely to give 'non-syllabled' grunts in the adult male's presence; and they consistently exchanged calls at a higher rate with the adult males than with other group members. An adult's type of calls did not obviously differ depending on whether their neighbour was kin or non-kin, but kin were overall more likely to give calls in the presence of kin, and to exchange calls with kin than with non-kin, although the association was not consistent throughout the two years of the study. With regard to the consequences of calling, subordinates were less likely to be feeding one minute after an approach by a fully adult male during which calls were exchanged than during silent approaches. In contrast to findings from studies of some other species, calling did not correlate with duration of grooming. We suggest that, among other functions, gorillas' 'close' calls mediate social interactions. One form of calls, 'non-syllabled' calls, are interpretable as appeasement signals. The broadest interpretation of the 'double grunt' is that it is an exaggerated announcement of presence, whose function is to attract attention to the caller, and to signal conditional future activity.

Demography of barren-ground grizzly bears

2003 ◽  
Vol 81 (2) ◽  
pp. 294-301 ◽  
Author(s):  
Philip D McLoughlin ◽  
Mitchell K Taylor ◽  
H Dean Cluff ◽  
Robert J Gau ◽  
Robert Mulders ◽  
...  
Keyword(s):  
Survival Rate ◽  
Litter Size ◽  
Birth Interval ◽  
Ursus Arctos ◽  
Survival Rates ◽  
Grizzly Bears ◽  
Adult Males ◽  
Barren Ground ◽  
Rate Of Increase ◽  
The Mean

Between May 1995 and June 1999, we equipped 81 barren-ground grizzly bears (Ursus arctos) with satellite radio collars within a study area of 235 000 km2, centred 400 km northeast of Yellowknife, Northwest Territories, Canada. We used data from radiotelemetry to estimate survival rates, reproductive parameters, and the finite rate of increase of the population (λ). The annual survival rate of adult females was estimated at 0.979 (95% confidence intervals (CI) = 0.955–0.998), while the survival rate of adult males was 0.986 (95% CI = 0.942–1.0). The cub survival rate was 0.737 (95% CI = 0.600–0.844) and the yearling survival rate was 0.683 (95% CI = 0.514–0.821). Cub litter size averaged 2.23 (SE = 0.13, n = 35), while yearling litter size decreased to a mean of 1.86 (SE = 0.12, n = 35). The mean litter size of females with 2-year-olds was 1.85 (SE = 0.15, n = 20). The mean birth interval was 2.8 years (SE = 0.3 years, n = 17). The mean reproductive interval, which is calculated by excluding the loss of whole litters from the sample, was 3.9 years (SE = 0.4 years, n = 9). Mean litter size divided by mean birth interval yielded an annual natality rate of 0.81 cubs per adult female per year. The mean age at first parturition was 8.1 years (SE = 0.5 years, n = 10). We believe the population to be currently stable or slightly increasing (λ = 1.033, 95% CI = 1.008–1.064).

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