scholarly journals Survival rates of adult and juvenile gyrfalcons in Iceland: estimates and drivers

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12404
Author(s):  
Frédéric Barraquand ◽  
Ólafur K. Nielsen
Keyword(s):  
Prey Density ◽  
Survival Rates ◽  
Environmental Drivers ◽  
Juvenile Survival ◽  
Recovery Model ◽  
Mark Recapture ◽  
Weather Effects ◽  
Main Prey ◽  
Positive Effects ◽  
Model Combining

Knowledge of survival rates and their potential covariation with environmental drivers, for both adults and juveniles, is paramount to forecast the population dynamics of long-lived animals. Long-lived bird and mammal populations are indeed very sensitive to change in survival rates, especially that of adults. Here we report the first survival estimates for the Icelandic gyrfalcon (Falco rusticolus) obtained by capture-mark-recapture methods. We use a mark-recapture-recovery model combining live and dead encounters into a unified analysis, in a Bayesian framework. Annual survival was estimated at 0.83 for adults and 0.40 for juveniles. Positive effects of main prey density on juvenile survival (5% increase in survival from min to max density) were possible though not likely. Weather effects on juvenile survival were even less likely. The variability in observed lifespan suggests that adult birds could suffer from human-induced alteration of survival rates.

scholarly journals Age-specific survival in an English Twite population.

2021 ◽  
Author(s):  
Ismini Gkourtsouli-Antoniadou ◽  
Steven R. Ewing ◽  
George Hudson ◽  
Michael A. Pearson ◽  
Julia Schroeder ◽  
...  
Keyword(s):  
Habitat Degradation ◽  
Survival Rates ◽  
Bird Species ◽  
Small Population ◽  
Juvenile Survival ◽  
Apparent Survival ◽  
Mark Recapture ◽  
The Uk ◽  
Rule Out

Like many bird species associated with agricultural habitats in the UK, the Twite Linaria flavirostris has undergone severe declines over recent decades due to habitat degradation, with populations in England, Wales and Ireland now restricted to a few small pockets. However, the demographic drivers of these declines are still largely unresolved. We estimated the survival of Twite from a small population at the southernmost edge of the English range in Derbyshire using capture-mark-recapture data from 2016–2019. Annual apparent survival for juveniles (0.14–0.34) was lower than for adults (0.29–0.56) and less than that of other Cardueline finches. Our results suggest that low juvenile survival may be one demographic driver underpinning the recent decline of the Derbyshire Twite population, although we also cannot rule out the possibility that differences in emigration of juveniles and adults from the population also contribute to the observed age-specific apparent survival rates.

SMEs strategic networks and innovative performance: a relational design and methodology for knowledge sharing

2020 ◽  
Vol 24 (6) ◽  
pp. 1369-1392 ◽  
Author(s):  
Elena-Mădălina Vătămănescu ◽  
Juan-Gabriel Cegarra-Navarro ◽  
Andreia Gabriela Andrei ◽  
Violeta-Mihaela Dincă ◽  
Vlad-Andrei Alexandru
Keyword(s):  
Knowledge Sharing ◽  
Structural Equation ◽  
Structural Model ◽  
Resource Scarcity ◽  
Content Type ◽  
Strategic Networks ◽  
Innovative Performance ◽  
Positive Effects ◽  
Model Combining ◽  
Fierce Competition

Purpose In the context of resource scarcity, the affiliation of small and medium-sized enterprises (SMEs) to strategic networks has emerged as a fruitful path towards knowledge sharing as a reaction to fierce competition and with a view to enhance their innovative performance. In this framework, this paper aims to investigate the influence exerted by a specific relational design (i.e. types of strategic networks) and methodology (i.e. channels and content) of knowledge sharing on SMEs innovative performance. Design/methodology/approach A questionnaire-based survey with 102 top managers of European SMEs in the industrial field was conducted from June to August 2019 and a partial least squares structural equation modelling technique was used. The database was initially filtered to ensure the adequacy of the sample and data was analysed using the statistics software package SmartPLS 3.0. Findings The results concluded that the structural model explains 38.5% of the variance in SMEs innovative performance, indicating the positive effects exerted by offline and online and by competitive knowledge sharing on the dependent variable. Research implications The study has both theoretical and practical implications in that it sets out a reference point for the key performance indicators for strategic networks structure, formation and development and, implicitly, for the selection of the most efficient relational design and methodology. Originality/value The pivotal originality elements reside in the advancement of a more comprehensive conceptual and structural model combining a two-fold operationalization of SMEs strategic networks (founded on business abilities or on the personality of the partner) and in the investigation of knowledge transfer processes at the inter-organizational levels within a context-centric approach.

Effect of Prey Density and Prey Size on Growth and Survival of Juvenile Walleye (Stizostedion vitreum vitreum)

1989 ◽  
Vol 46 (8) ◽  
pp. 1323-1328 ◽  
Author(s):  
Michael G. Fox
Keyword(s):  
Prey Density ◽  
Prey Availability ◽  
Food Limitation ◽  
Survival Rates ◽  
Stizostedion Vitreum ◽  
Growth And Survival ◽  
First Feeding ◽  
Length Increase ◽  
Prey Length ◽  
Chironomid Biomass

I investigated the influence of food availability on growth and survival of walleye (Stizostedion vitreum vitreum) fry stocked in six fertilized experimental ponds (density 40 fish∙m−3) and reared for 8 wk. Walleye fed largely on chironomid larvae and cyclopoid copepods in weeks 1 and 2, and chironomids thereafter. Prey choice and consumption were strongly influenced by chironomid biomass in the benthos, and to a lesser extent by zoo-plankton density. Weekly length increase of the populations and mean length in week 7 were significantly correlated with chironomid benthic biomass and mean prey length. Chironomid biomass and density of large zoo-plankton together explained 56% of the variation in the weekly population growth rate. Despite obvious food limitation in the second half of the experiment, pond survival rate was not significantly correlated with mean prey density, mean stomach fullness, or percentage of fish with empty stomachs. The results indicate that juvenile walleye growth can be regulated by the density and size of available prey. Prey availability apparently does not regulate short term juvenile walleye survival rates after the period around first feeding.

Estimating the survival rates of Soay sheep from mark—recapture—recovery data

2017 ◽  
pp. 317-329
Author(s):  
Walter Zucchini ◽  
Iain L. MacDonald ◽  
Roland Langrock
Keyword(s):  
Survival Rates ◽  
Mark Recapture ◽  
Soay Sheep

scholarly journals Global vegetation variability and its response to elevated CO<sub>2</sub>, global warming, and climate variability – a study using the offline SSiB4/TRIFFID model and satellite data

2019 ◽  
Vol 10 (1) ◽  
pp. 9-29 ◽  
Author(s):  
Ye Liu ◽  
Yongkang Xue ◽  
Glen MacDonald ◽  
Peter Cox ◽  
Zhengqiu Zhang
Keyword(s):  
Global Warming ◽  
Climate Variability ◽  
Environmental Drivers ◽  
Arid Areas ◽  
Area Index ◽  
Substantial Impact ◽  
Positive Effects ◽  
Vegetation Fraction ◽  
Before And After ◽  
Semi Arid

Abstract. The climate regime shift during the 1980s had a substantial impact on the terrestrial ecosystems and vegetation at different scales. However, the mechanisms driving vegetation changes, before and after the shift, remain unclear. In this study, we used a biophysical dynamic vegetation model to estimate large-scale trends in terms of carbon fixation, vegetation growth, and expansion during the period 1958–2007, and to attribute these changes to environmental drivers including elevated atmospheric CO2 concentration (hereafter eCO2), global warming, and climate variability (hereafter CV). Simulated leaf area index (LAI) and gross primary production (GPP) were evaluated against observation-based data. Significant spatial correlations are found (correlations > 0.87), along with regionally varying temporal correlations of 0.34–0.80 for LAI and 0.45–0.83 for GPP. More than 40 % of the global land area shows significant positive (increase) or negative (decrease) trends in LAI and GPP during 1958–2007. Regions over the globe show different characteristics in terms of ecosystem trends before and after the 1980s. While 11.7 % and 19.3 % of land have had consistently positive LAI and GPP trends, respectively, since 1958, 17.1 % and 20.1 % of land saw LAI and GPP trends, respectively, reverse during the 1980s. Vegetation fraction cover (FRAC) trends, representing vegetation expansion and/or shrinking, are found at the edges of semi-arid areas and polar areas. Environmental drivers affect the change in ecosystem trend over different regions. Overall, eCO2 consistently contributes to positive LAI and GPP trends in the tropics. Global warming mostly affects LAI, with positive effects in high latitudes and negative effects in subtropical semi-arid areas. CV is found to dominate the variability of FRAC, LAI, and GPP in the semi-humid and semi-arid areas. The eCO2 and global warming effects increased after the 1980s, while the CV effect reversed during the 1980s. In addition, plant competition is shown to have played an important role in determining which driver dominated the regional trends. This paper presents new insight into ecosystem variability and changes in the varying climate since the 1950s.

scholarly journals Movements and Survival of Lark Bunting Fledglings

The Condor ◽  
2001 ◽  
Vol 103 (3) ◽  
pp. 643-647 ◽  
Author(s):  
Amy A. Yackel Adams ◽  
Susan K. Skagen ◽  
Rod D. Adams
Keyword(s):  
Radio Telemetry ◽  
Survival Rates ◽  
Juvenile Survival ◽  
Daily Survival ◽  
Brood Division ◽  
Source Sink ◽  
Care Period

Abstract We quantified post-fledging pre-independence behavior and survival in Lark Buntings (Calamospiza melanocorys) using radio-telemetry. Brood division was recorded in six broods and was maintained throughout the observed fledgling care period. Chicks were capable of short flights (up to 25 m) by fledgling day 6 and longer flights (to 100 m) by fledgling day 13. During the first three weeks after fledging, juveniles moved as far as 800 m from nests. Nine of 23 (39%) monitored fledglings died within 15 days of fledging, primarily due to predation by raptors. Daily survival rates were 0.953 ± 0.019 for fledgling days 0–9, 0.955 ± 0.038 for fledgling days 10–20, and 0.953 ± 0.015 for fledgling days 0–20. The probability of surviving fledgling days 0–20 was 0.367. More quantification of juvenile survival is clearly needed to understand the role of post-fledging mortality in source-sink dynamics. Los Movimientos y Supervivencia de los Volantones de Calamospiza melanocorys Resumen. Cuantificamos la conducta y la supervivencia de volantones de Calamospiza melanocorys antes de independizarse de sus padres usando telemetría de radio. La división de la nidada se registró en seis nidadas y se mantuvo a través del período del cuidado de los volantones. Tras seis días de haber abandonado el nido, los polluelos eran capaces de realizar vuelos cortos (de hasta 25 m) y para el día trece ya realizaban vuelos más largos (a 100 m). Durante las primeras tres semanas después de salir del nido, los juveniles se movieron hasta 800 m de los nidos. Nueve de 23 (39%) volantones se murieron en los primeros 15 días fuera del nido, principalmente debido a depredación por aves rapaces. Las tasas diarias de supervivencia fueron de 0.953 ± 0.019 para los días 0 a 9, 0.955 ± 0.038 para los días 10 a 20, y 0.954 ± 0.015 para días 0 a 20. La probabilidad de sobrevivir entre los días 0 y 20 fue de 0.367. Se necesita más cuantificacion de la sobrevivencia en la etapa juvenil para entender el papel de la mortalidad tras la salida del nido en la dinámica de fuente-sumideros.

scholarly journals Effects of Supplemental Food on Parental-Care Strategies and Juvenile Survival of Northern Goshawks

The Auk ◽  
2001 ◽  
Vol 118 (2) ◽  
pp. 352-365 ◽  
Author(s):  
Sarah R. Dewey ◽  
Patricia L. Kennedy
Keyword(s):  
Adult Female ◽  
Survival Rates ◽  
Mortality Factor ◽  
Food Supplementation ◽  
Juvenile Survival ◽  
Nest Attendance ◽  
Additional Food ◽  
Supplemental Food ◽  
Risk Of Predation ◽  
Northern Goshawks

Abstract Using food supplementation, we tested whether food limits juvenile survival in a population of Northern Goshawks (Accipiter gentilis) in northeastern Utah. The influence of additional food on female nest attendance also was investigated because those strategies may influence predation mortality rates of juveniles. We provided supplemental food near 13 nests from close to hatching until close to independence during the 1996 and 1997 breeding seasons. Thirteen additional nests served as controls and received no supplemental food. We compared the following variables at treatment and control nests: (1) adult female mass, (2) nestling mass and size, (3) female nest attendance, and (4) juvenile survival. Following supplemental feeding, adult females from treatment nests were heavier than their control counterparts, and remained closer to the nest during the latter part of the nestling period and throughout the postfledging period. Nestlings from supplemented nests were significantly heavier than those from unsupplemented nests, but results for size measurements were equivocal. Survival rates for treatment nestlings were significantly higher than controls in 1997, but not in 1996. Those results support the hypothesis that food does not limit avian reproductive success on an annual basis. Most deaths in 1997 were the result of starvation or sibling competition. That observation, and the fact that fed nestlings were heavier, is consistent with the idea that treatment nestlings were in improved nutritional condition. Overall patterns of mass and nest-attendance for adult female goshawks supports the hypothesis that female condition and behavior are adjusted in response to food supplies. However, it is less clear what role the females' presence in the nest stand plays in mediating juvenile deaths, because we did not document predation as a primary mortality factor during the two years of this study. The apparent flexibility in female nest attendance behavior suggests that such plasticity may be an adaptation to lower the risk of predation.

Juvenile survival and recruitment in a population of Weddell seals (Leptonychotes weddellii) in McMurdo Sound, Antarctica

1987 ◽  
Vol 65 (12) ◽  
pp. 2993-2997 ◽  
Author(s):  
J. Ward Testa
Keyword(s):  
Census Data ◽  
Survival Rates ◽  
Breeding Population ◽  
Weddell Seal ◽  
Adult Survival ◽  
Juvenile Survival ◽  
Apparent Survival ◽  
Mcmurdo Sound ◽  
Juvenile Dispersal ◽  
Weddell Seals

Survival and recruitment of Weddell seal pups were studied in eastern McMurdo Sound, Antarctica. Pups were marked and their apparent survival estimated by mark–recapture methods. The resulting estimates were used together with published estimates of adult survival, yearly sighting probabilities, and direct counts of pup production to simulate the dynamics of the population and evaluate the assumption that it is closed to immigration. Estimates derived from census data in 1982 and 1983 were over five times larger than those simulated. This discrepancy was due to the extremely low juvenile survival rates calculated from marked seals. Since few animals born in Erebus Bay return to breed, the large adult breeding population must be the result of substantial immigration, indicating an important role for juvenile dispersal in the population dynamics of Weddell seals.

scholarly journals Mark-recapture estimates of daily survival rates of two damselflies (Coenagrion puella and Ischnura elegans)

2001 ◽  
Vol 79 (5) ◽  
pp. 895-899 ◽  
Author(s):  
Bradley R. Anholt ◽  
Christoph Vorburger ◽  
Peter Knaus
Keyword(s):  
Survival Rates ◽  
Mark Recapture ◽  
Ischnura Elegans ◽  
Daily Survival

scholarly journals Cyclic dynamics of snowshoe hares on a small island in the Yukon

2002 ◽  
Vol 80 (8) ◽  
pp. 1442-1450 ◽  
Author(s):  
Charles J Krebs ◽  
Todd N Zimmerling ◽  
Claire Jardine ◽  
Kim A Trostel ◽  
Alice J Kenney ◽  
...  
Keyword(s):  
Population Decline ◽  
Survival Rates ◽  
Ground Squirrels ◽  
Adult Survival ◽  
Small Island ◽  
Juvenile Survival ◽  
Lower Amplitude ◽  
Arctic Ground Squirrels ◽  
Reproductive Rates ◽  
Survival Differences

Snowshoe hare (Lepus americanus) populations were monitored from 1977 to 2001 on Jacquot Island (5 km2) in Kluane Lake, southwestern Yukon, and on nearby mainland sites. Jacquot Island hares averaged twice the density of mainland control populations and, although they show 10-year cycles, fluctuate with much lower amplitude than mainland populations. Three separate intensive studies over 6 years attempted to determine what caused these differences. We tested two hypotheses to explain the dynamics. Reproductive rates of hares were similar on Jacquot Island and the mainland. Adult survival rates were higher on the island in most years, with the exception of years of population decline. Juvenile survival rates from 0 to 30 days of life were much higher on the island than on the mainland except for decline summers. The adult- and juvenile-survival differences between the island and the mainland were explained most consistently by predation. Improved survival on the island is correlated with a reduction in the numbers and types of predators found on Jacquot Island compared with the mainland. In particular, red squirrels were rare on Jacquot Island, arctic ground squirrels were absent, and the larger predators, like lynx and great-horned owls, were sporadic in occurrence on this small island.

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