Estimation of juvenile survival, adult survival, and age-specific pupping probabilities for the female grey seal (Halichoerus gryprus) on Sable Island from capture-recapture data

2000 ◽  
Vol 57 (1) ◽  
pp. 247-253 ◽  
Author(s):  
Carl J Schwarz ◽  
Wayne T Stobo
Keyword(s):  
Survival Rate ◽  
Survival Rates ◽  
Adult Survival ◽  
Juvenile Survival ◽  
Grey Seal ◽  
Capture Recapture ◽  
Adult Survival Rate

We use a longitudinal capture-recapture study from resightings of grey seals (Halichoerus gryprus) branded as young on Sable Island to estimate (i) the juvenile survival rate from the time of branding to age 4, (ii) the yearly adult survival rate from age 4 to age 9, and (iii) the age-specific pupping probabilities, i.e., the probability that a seal will first give birth at each age. The estimated juvenile survival rate from branding (just after weaning) to age 4 ranged from 70 to 80%; however, the lower values are known to be biased low because the study was terminated early. The estimated yearly adult survival rates for ages 4-9 ranged from 0.88 to 0.92·year-1. The estimated probabilities of first giving birth to a young seal (pupping) at ages 4-9 are 0.28, 0.41, 0.18, 0.06, 0.05, and 0.02, respectively, and the estimated average age of first pupping is 5.2 years.

Estimates of adult survival rate for three colonies of Sooty Shearwater (Puffinus griseus) in New Zealand

2008 ◽  
Vol 108 (3) ◽  
pp. 237-250 ◽  
Author(s):  
Rosemary J. Clucas ◽  
David J. Fletcher ◽  
Henrik Moller
Keyword(s):  
New Zealand ◽  
Survival Rate ◽  
Adult Survival ◽  
Adult Survival Rate

scholarly journals Juvenile and Adult Survival of Swainson's Thrush (Catharus Ustulatus) in Coastal California: Annual Estimates Using Capture-Recapture Analyses

The Auk ◽  
2003 ◽  
Vol 120 (4) ◽  
pp. 1188-1194
Author(s):  
Thomas Gardali ◽  
Daniel C. Barton ◽  
Jennifer D. White ◽  
Geoffrey R. Geupel
Keyword(s):  
Adult Survival ◽  
Juvenile Survival ◽  
Survival Ratio ◽  
Catharus Ustulatus ◽  
Survival Estimate ◽  
Neotropical Migrant ◽  
Probability Estimates ◽  
Capture Recapture ◽  
Source Sink ◽  
Range Of Values

Abstract We estimated annual rates of survival for juvenile and adult Swainson's Thrushes (Catharus ustulatus) using capture-recapture analyses from 22 years of mist-neting data in coastal California (n= 2,651 individual captures). Our apparent survival estimate was 56% for adults and 25% for juveniles. We are the first to estimate an annual juvenile survival rate for a Neotropical migrant using capture-recapture probability estimates. Like most estimates of annual survival, we could not distinguish between dispersal away from our study area (which is likely high for juveniles) and mortality. Hence, survival is underestimated. However, our juvenile survival estimate did not include the period from fledging to independence, a time when mortality can be high. Many researchers have assumed juvenile survival to be half that of adult survival in population models (e.g. source-sink). Our juvenile to adult survival ratio was 45% (95% CI = 27 to 65%). We caution researchers from simply assuming that juvenile survival approximates half of adult survival when modeling populations and suggest using a range of values. Using a range of values is prudent because of the potential for annual variation, site-specific variation, and especially because estimates are imprecise or completely lacking.

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 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.

scholarly journals Temporal and spatial variation in age-specific survival rates of a long-lived mammal, the Hawaiian monk seal

2006 ◽  
Vol 274 (1608) ◽  
pp. 407-415 ◽  
Author(s):  
Jason D Baker ◽  
Paul M Thompson
Keyword(s):  
Survival Rates ◽  
Adult Survival ◽  
Age Classes ◽  
Temporal And Spatial Variation ◽  
Monachus Schauinslandi ◽  
Breeding Sites ◽  
Capture Recapture ◽  
Temporal And Spatial ◽  
Spatio Temporal ◽  
Monk Seals

Estimates of variability in pinniped survival rates are generally based on observations at single sites, so it is not certain whether observed rates represent the whole population. Here, we provide a comprehensive analysis of spatio-temporal variation in age-specific survival rates for endangered Hawaiian monk seals ( Monachus schauinslandi ) based on capture–recapture analyses of more than 85% of the pups weaned in this population over the last two decades. Uniquely, these data have been collected from six subpopulations, encompassing all major breeding sites across its 1800 km long core range. Analyses of individual subpopulations revealed similar patterns in age-specific survival, characterized by the relatively low survival rates from weaning to 2 years of age, intermediate rates to 4 years of age, and then by relatively high ‘mature’ survival rates until 17 years of age, after which a senescent decline was observed. Juvenile, subadult and adult survival rates all varied significantly over time. Trends in survival among subpopulations were coherent with their relative geographical positions, suggesting regional structuring and connectedness within the archipelago. Survival rates for different age classes tended to be positively correlated, suggesting that similar factors may influence the survival for seals of all ages.

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