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 Postweaning maternal care increases male chimpanzee reproductive success

2020 ◽  
Vol 6 (38) ◽  
pp. eaaz5746
Author(s):  
Catherine Crockford ◽  
Liran Samuni ◽  
Linda Vigilant ◽  
Roman M. Wittig
Keyword(s):  
Reproductive Success ◽  
Parental Investment ◽  
Maternal Care ◽  
Parental Loss ◽  
Male Reproductive Success ◽  
Complex Societies ◽  
Successful Reproduction ◽  
Using Data

Humans are unusual among animals for continuing to provision and care for their offspring until adulthood. This “prolonged dependency” is considered key for the evolution of other notable human traits, such as large brains, complex societies, and extended postreproductive lifespans. Prolonged dependency must therefore have evolved under conditions in which reproductive success is gained with parental investment and diminished with early parental loss. We tested this idea using data from wild chimpanzees, which have similarly extended immature years as humans and prolonged mother-offspring associations. Males who lost their mothers after weaning but before maturity began reproducing later and had lower average reproductive success. Thus, persistent mother-immature son associations seem vital for enhancing male reproductive success, although mothers barely provision sons after weaning. We posit that these associations lead to social gains, crucial for successful reproduction in complex social societies, and offer insights into the evolution of prolonged dependency.

scholarly journals Proposed power transmission lines in Cambodia constitute a significant new threat to the largest population of the Critically Endangered Bengal floricanHoubaropsis bengalensis

Oryx ◽  
2016 ◽  
Vol 52 (1) ◽  
pp. 147-155 ◽  
Author(s):  
Simon P. Mahood ◽  
João P. Silva ◽  
Paul M. Dolman ◽  
Robert J. Burnside
Keyword(s):  
Transmission Lines ◽  
Power Transmission ◽  
Survival Rates ◽  
Critically Endangered ◽  
Adult Survival ◽  
Power Transmission Lines ◽  
Migration Routes ◽  
Tonle Sap ◽  
Using Data ◽  
Breeding Seasons

AbstractThe remaining Indochina population of the Critically Endangered Bengal floricanHoubaropsis bengalensisbreeds in the floodplain of Cambodia's Tonle Sap Lake. The population has declined substantially but survival rates have not been published previously. Survival could potentially be reduced by the planned construction of high-tension power transmission lines that may begin in 2016. Using data from 17 individuals monitored by satellite transmitters over 4 years we estimated the annual adult survival rate to be 89.9% (95% CI 82.2–97.6%), which is comparable to that of other bustards. Interrogation of movement paths revealed that for the 13 individuals for which we had sufficient data for non-breeding seasons, all annual migration routes between breeding and non-breeding areas crossed the proposed route of the transmission line. The route also impinged on the margins of one important and one minor breeding concentration. A review of bustard collision rates confirmed the vulnerability of bustards to power lines, and the proposed development therefore presents an additional threat to the future of this species in Indochina.

scholarly journals Survival of a long-lived single island endemic, the Raso lark Alauda razae, in relation to age, fluctuating population and rainfall

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
E. G. Dierickx ◽  
R. A. Robinson ◽  
M. de L. Brooke
Keyword(s):  
Strong Evidence ◽  
Survival Rates ◽  
Adult Survival ◽  
Tropical Species ◽  
High Survival ◽  
Cape Verdean ◽  
Island Endemic ◽  
The Face ◽  
Dry Conditions ◽  
Population Sizes

AbstractEstimating and understanding variation in survival rates is crucial for the management of threatened species, especially those with limited population sizes and/or restricted ranges. Using a capture-resighting dataset covering 2004–2017, we estimate adult survival in the Raso lark Alauda razae, a Critically Endangered single-island Cape Verdean endemic, whose population varied 25-fold during the study. Average annual adult survival was similar for males (0.813 ± 0.011) and females (0.826 ± 0.011) over the period. These values are high for a temperate passerine but not unusual for an insular tropical species like the lark. The oldest bird was recorded 13 years after first ringing. There was strong evidence that survival varied among years (between 0.57 and 0.95), being generally higher in wetter years. Survival, especially of males, was lower when the population was large, but only in drier years. Survival declined with age but there was no evidence that this decline was other than linear. High survival, even in the face of dry conditions, at least when the population is depressed, has probably contributed to the persistence of the species on its 7 km2 island home over several centuries.

scholarly journals Juvenile and Adult Survival in the Sociable Weaver (Philetairus Socius), A Southern-Temperate Colonial Cooperative Breeder in Africa

The Auk ◽  
2004 ◽  
Vol 121 (4) ◽  
pp. 1199-1207
Author(s):  
Rita Covas ◽  
Charles R. Brown ◽  
Mark D. Anderson ◽  
Mary Bomberger Brown
Keyword(s):  
Survival Rates ◽  
Adult Survival ◽  
Easy Access ◽  
High Survival ◽  
Capture Recapture ◽  
Sociable Weavers ◽  
Philetairus Socius ◽  
Similar Survival ◽  
Survival Patterns ◽  
Access To Food

Abstract We used capture-recapture analyses to describe juvenile and adult survival from 1993 to 2001 in a population of Sociable Weavers (Philetairus socius), a colonial, cooperatively breeding passerine of southern Africa. We examined temporal variation in survival and the role that the breeding season's length and environmental factors play in determining survival patterns in the population. Annual survival probability (mean ± SE) was 0.66 ± 0.02. In contrast to most passerines, juveniles and adults had similar survival probabilities; survival rates did not vary significantly between years. We found no relationship among temperature, rainfall, and survival. Relatively high survival rates in Sociable Weavers probably result from a benign climate and easy access to food in winter. Juvenile survival may also be enhanced by prolonged parental care and delayed dispersal.

scholarly journals Demographic drivers of decline and recovery in an Afro-Palaearctic migratory bird population

2016 ◽  
Vol 283 (1842) ◽  
pp. 20161387 ◽  
Author(s):  
Catriona A. Morrison ◽  
Robert A. Robinson ◽  
Simon J. Butler ◽  
Jacquie A. Clark ◽  
Jennifer A. Gill
Keyword(s):  
Population Growth ◽  
Survival Rates ◽  
Bird Species ◽  
Migratory Bird ◽  
Adult Survival ◽  
High Survival ◽  
Population Declines ◽  
High Productivity ◽  
Population Growth Rates ◽  
Sub Saharan

Across Europe, rapid population declines are ongoing in many Afro-Palaearctic migratory bird species, but the development of appropriate conservation actions across such large migratory ranges is severely constrained by lack of understanding of the demographic drivers of these declines. By constructing regional integrated population models (IPMs) for one of the suite of migratory species that is declining in the southeast of Britain but increasing in the northwest, we show that, while annual population growth rates in both regions vary with adult survival, the divergent regional trajectories are primarily a consequence of differences in productivity. Between 1994 and 2012, annual survival and productivity rates ranged over similar levels in both regions, but high productivity rates were rarer in the declining southeast population and never coincided with high survival rates. By contrast, population growth in the northwest was fuelled by several years in which higher productivity coincided with high survival rates. Simulated population trajectories suggest that realistic improvements in productivity could have reversed the decline (i.e. recovery of the population index to more than or equal to 1) in the southeast. Consequently, actions to improve productivity on European breeding grounds are likely to be a more fruitful and achievable means of reversing migrant declines than actions to improve survival on breeding, passage or sub-Saharan wintering grounds.

scholarly journals Assessing factors affecting adult female white-tailed deer survival in the Northern Great Plains

2018 ◽  
Vol 45 (8) ◽  
pp. 679 ◽  
Author(s):  
Katherine L. Moratz ◽  
Bailey S. Gullikson ◽  
Eric S. Michel ◽  
Jonathan A. Jenks ◽  
Daniel M. Grove ◽  
...  
Keyword(s):  
Great Plains ◽  
Adult Female ◽  
Survival Rates ◽  
Adult Survival ◽  
Northern Great Plains ◽  
Late Winter ◽  
High Survival ◽  
Factors Affecting ◽  
Time Period ◽  
Specific Mortality

Context Documenting cause-specific mortality and deriving survival estimates for a population are both vital to understanding potential restrictions to population growth. Survival varies among populations of the same species and depends on several factors, including climatic events, density-dependent and density-independent factors, observed predator composition and whether recreational hunting occurs. Therefore, understanding factors affecting adult survival and estimating survival rates at biologically important times will help refine management of these populations. Aims We aimed to assess cause-specific mortality, estimate survival rates, and determine at what part of the winter (January to April) most mortalities occurred for female white-tailed deer located in the Northern Great Plains region of the USA. Methods We captured 165 adult female white-tailed deer (Odocoileus virginianus) located in western North Dakota and north-western South Dakota, USA, during the winters of 2014 and 2015. We fitted individuals with Very High Frequency (VHF) radio-collars and located them 1–3 times per week to monitor survival. We investigated all mortalities to establish proximate cause of death. Key Results Survival was lowest during our Hunt time period (S=0.93), although hunter harvest was not the leading cause of mortality. Predation was the greatest source of mortality, particularly during our Post-hunt time period. Additionally, almost 90% of mortalities occurring during the Post-hunt time period happened during late winter before spring green up. Conclusions and Implications Predation was the main source of mortality for adult females in our study, with coyotes (Canis latrans) being the sole predator capable of depredation in our study area. Predation by coyotes may indicate that potential factors, including winter severity and nutritional restrictions, have decreased female body condition, making individuals more susceptible to predation. Although we report relatively high survival, managers should consider the possibility that coyotes may impact adult populations, particularly in regions where other large-sized predators occur, or in regions where coyotes are newly established. Managers should also acknowledge that overwinter density estimates may need to be adjusted during severe winters to account for mortalities that occur after population surveys are conducted.

The demography and cooperative breeding behaviour of the rufous treecreeper, Climacteris rufa

2001 ◽  
Vol 49 (5) ◽  
pp. 515 ◽  
Author(s):  
Gary W. Luck
Keyword(s):  
Reproductive Success ◽  
Cooperative Breeding ◽  
Survival Rates ◽  
Cost Benefit ◽  
Social Organisation ◽  
Adult Survival ◽  
Male And Female ◽  
Breeding Behaviour ◽  
Territory Defence ◽  
Primary Male

I examined the demography and cooperative breeding behaviour of the rufous treecreeper, Climacteris rufa, in the south-west of Western Australia. Social organisation, breeding behaviour, reproductive success, survival and dispersal were measured over 3 years. The species lived in cooperatively breeding groups of 2–7 individuals, which occupied a territory year round. Most groups comprised a primary male and female (probably breeding) and offspring from previous breeding seasons (helpers). Territory defence was variable, particularly during the breeding season when individuals would feed nestlings in adjacent territories. The social organisation of the species was based on neighbourhoods of interacting territories. All group members provisioned nestlings, and the primary male and female significantly reduced their provisioning effort as the number of helpers increased. Total nest success for the 3 years was 78% and mean annual productivity was 2.1 (0.18). Fledgling and juvenile survival rates were relatively high (0.76 and 0.46 respectively), but adult survival rate (0.76) was comparable to that of other passerines of the temperate Southern Hemisphere. Dispersal of juveniles appeared to be female-biased. The demography of the rufous treecreeper was consistent with other old endemic Australian passerines. High adult survival resulted in few breeding vacancies for non-breeders and this is probably an important factor in the evolution of cooperative breeding in the species. Cooperative breeding also appears to be influenced by habitat saturation and a cost–benefit trade-off between remaining as a helper in high-quality territories and dispersing to poorer-quality territories where reproductive success may be low.

scholarly journals Red deer Cervus elaphus blink more in larger groups

2020 ◽  
Author(s):  
Zeke W. Rowe ◽  
Joseph H. Robins ◽  
Sean A. Rands
Keyword(s):  
Group Size ◽  
Cervus Elaphus ◽  
Red Deer ◽  
Group Living ◽  
Blink Rate ◽  
Non Invasive ◽  
Group Members ◽  
The Individual ◽  
Perceived Predation Risk ◽  
Meaningful Measure

ABSTRACTMost animals need to spend time being vigilant for predators, at the expense of other activities such as foraging. Group-living animals can benefit from the shared vigilance effort of other group members, with individuals reducing personal vigilance effort as group size increases. Behaviours like active scanning or head lifting are usually used to quantify vigilance, but may not be accurate measures as the individual could be conducting them for other purposes. We suggest that measuring an animal’s blinking rate gives a meaningful measure of vigilance: increased blinking implies reduced vigilance, as the animal cannot detect predators when its eyes are closed. We demonstrate that as group size increases in red deer, individuals increase their blink rate, confirming the prediction that vigilance should decrease. Blinking is a simple non-invasive measure, and offers a useful metric for assessing the welfare of animals experiencing an increase in perceived predation risk or other stressors.

scholarly journals Long-term repeatability in social behaviours suggests stable social phenotypes in wild chimpanzees

2020 ◽  
Author(s):  
Patrick J. Tkaczynski ◽  
Alexander Mielke ◽  
Liran Samuni ◽  
Anna Preis ◽  
Roman Wittig ◽  
...  
Keyword(s):  
Individual Differences ◽  
Social Behaviour ◽  
Group Living ◽  
Ecological Factors ◽  
Life History Stage ◽  
Decision Making Processes ◽  
Group Members ◽  
Using Data ◽  
Social Behaviours

AbstractAnimals living in social groups navigate challenges when competing and cooperating with other group members. Changes in demographics, dominance hierarchies or ecological factors, such as food availability or disease prevalence, are expected to influence decision-making processes regarding social interactions. Therefore, it could be expected individuals show flexibility in social behaviour over time to maximise the fitness benefits of social living. To date, research across species has shown that stable inter-individual differences in social behaviour exist, but mostly over relatively short data collection time periods. Using data spanning over 20 years, we demonstrate that multiple social behaviours are repeatable over the long-term in wild chimpanzees, a long-lived species occupying a complex fission-fusion society. We controlled for temporal, ecological and demographic changes, limiting pseudo-repeatability. We conclude that chimpanzees living in natural ecological settings have relatively stable long-term social phenotypes over years that may be independent of life history stage or strategies. Our results add to the growing body of literature suggesting consistent individual differences in social tendencies are more likely the rule rather than the exception in group-living animals.

Persistence of giants: population dynamics of the limpet Scutellastra laticostata on rocky shores in Western Australia

2020 ◽  
Vol 646 ◽  
pp. 79-92
Author(s):  
RE Scheibling ◽  
R Black
Keyword(s):  
Population Dynamics ◽  
Western Australia ◽  
Size Structure ◽  
Survival Rates ◽  
Maximum Size ◽  
High Rate ◽  
Adult Survival ◽  
Rocky Shores ◽  
Adult Size ◽  
Decadal Time Scale

Population dynamics and life history traits of the ‘giant’ limpet Scutellastra laticostata on intertidal limestone platforms at Rottnest Island, Western Australia, were recorded by interannual (January/February) monitoring of limpet density and size structure, and relocation of marked individuals, at 3 locations over periods of 13-16 yr between 1993 and 2020. Limpet densities ranged from 4 to 9 ind. m-2 on wave-swept seaward margins of platforms at 2 locations and on a rocky notch at the landward margin of the platform at a third. Juvenile recruits (25-55 mm shell length) were present each year, usually at low densities (<1 m-2), but localized pulses of recruitment occurred in some years. Annual survival rates of marked limpets varied among sites and cohorts, ranging from 0.42 yr-1 at the notch to 0.79 and 0.87 yr-1 on the platforms. A mass mortality of limpets on the platforms occurred in 2003, likely mediated by thermal stress during daytime low tides, coincident with high air temperatures and calm seas. Juveniles grew rapidly to adult size within 2 yr. Asymptotic size (L∞, von Bertalanffy growth model) ranged from 89 to 97 mm, and maximum size from 100 to 113 mm, on platforms. Growth rate and maximum size were lower on the notch. Our empirical observations and simulation models suggest that these populations are relatively stable on a decadal time scale. The frequency and magnitude of recruitment pulses and high rate of adult survival provide considerable inertia, enabling persistence of these populations in the face of sporadic climatic extremes.

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