Environmental and biological factors influencing maternal attendance patterns of Steller sea lions (Eumetopias jubatus) in Russia

Burkanov, Vladimir N.; Gurarie, Eliezer; Altukhov, Alexey; Mamaev, Evgeny; Permyakov, Peter A.; Трухин, А. М.; Waite, Jason N.; Gelatt, Tom

doi:10.1644/10-mamm-a-194.1

Cited by 21 publications

(18 citation statements)

References 29 publications

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“…First year survival for many animals depends on early conditions, for example on body mass at birth or within the first weeks of growth [ 6 , 43 ], which in turn is often closely related to adult female condition. Recent studies of maternal attendance patterns indicate that over the period of our study, Medny Island females had a longer postpartum period, the time after pup birth until the first foraging trip, than at other Steller sea lion rookeries, suggesting that adult females there were in better condition and capable of fasting and suckling their pups for a greater length of time during the first suckling bout [ 13 ].…”

Section: Discussionmentioning

confidence: 99%

“…Females that breed in consecutive years have less time to recover their body condition, and less resources to invest in their next pup, consequently first year survival of those pups might be lower. If a greater fraction of reproductive age females skip birth years on Medny Island, this could partly explain their higher apparent body condition as indicated by longer post-partum periods [ 13 ].…”

Section: Discussionmentioning

confidence: 99%

“…Low adult survival on Medny Island may be due to some long-term negative effect on adult survival that is potentially preventing the Medny population from recovering, but estimates of birth rates are required before making a proper conclusion. Lower adult survival may suggest that these sea lions experience predation, disease or food limitation during the winter time, as there is no evidence of nutritional stress during summer [ 13 , 59 ]. We have not observed any overt sign of unusual disease mortality [ 36 ], and predation seems an unlikely explanation given that killer whales have never been observed to prey upon Steller sea lions during summer on Medny Island, despite frequent observations of predation upon juvenile male northern fur seals there.…”

Section: Discussionmentioning

confidence: 99%

“…The population trends at most of these Steller sea lion rookeries in Russia followed a similar pattern of decline between approximately 1975 and 1990, but during the 1990’s there was a divergence of trends across the region. In the Kuril Islands and in the Sea of Okhotsk the population started to increase and was still increasing in both areas through at least 2010 [ 13 ]. In Eastern Kamchatka the population was fairly stable with no discernible trend between 1990 and 2010, while on the Commander Islands the population has continued to decline through the present time [ 11 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

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Age Specific Survival Rates of Steller Sea Lions at Rookeries with Divergent Population Trends in the Russian Far East

Altukhov

Andrews

Calkins³

et al. 2015

PLoS ONE

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After a dramatic population decline, Steller sea lions have begun to recover throughout most of their range. However, Steller sea lions in the Western Aleutians and Commander Islands are continuing to decline. Comparing survival rates between regions with different population trends may provide insights into the factors driving the dynamics, but published data on vital rates have been extremely scarce, especially in regions where the populations are still declining. Fortunately, an unprecedented dataset of marked Steller sea lions at rookeries in the Russian Far East is available, allowing us to determine age and sex specific survival in sea lions up to 22 years old. We focused on survival rates in three areas in the Russian range with differing population trends: the Commander Islands (Medny Island rookery), Eastern Kamchatka (Kozlov Cape rookery) and the Kuril Islands (four rookeries). Survival rates differed between these three regions, though not necessarily as predicted by population trends. Pup survival was higher where the populations were declining (Medny Island) or not recovering (Kozlov Cape) than in all Kuril Island rookeries. The lowest adult (> 3 years old) female survival was found on Medny Island and this may be responsible for the continued population decline there. However, the highest adult survival was found at Kozlov Cape, not in the Kuril Islands where the population is increasing, so we suggest that differences in birth rates might be an important driver of these divergent population trends. High pup survival on the Commander Islands and Kamchatka Coast may be a consequence of less frequent (e.g. biennial) reproduction there, which may permit females that skip birth years to invest more in their offspring, leading to higher pup survival, but this hypothesis awaits measurement of birth rates in these areas.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Age Specific Survival Rates of Steller Sea Lions at Rookeries with Divergent Population Trends in the Russian Far East

Altukhov

Andrews

Calkins³

et al. 2015

PLoS ONE

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“…For the “home” state, we assumed a quadratic change in detection over the season with a fixed slope among years. The detection change over the pupping season took into account the decline in visit duration for nursing adult females [ 21 , 32 ] and also the increase in water activity by pups [ 15 , 18 , 33 ]. The varying intercept of the detection model allowed for annual variation in observation quality, resulting from weather or observer biases.…”

Section: Methodsmentioning

confidence: 99%

Estimating dispersal rates of Steller sea lion (Eumetopias jubatus) mother-pup pairs from a natal rookery using mark-resight data

et al. 2017

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To monitor population trends of Steller sea lions (Eumetopias jubatus) in Alaska, newborn pups are counted during aerial surveys. These surveys are scheduled to occur after the majority of pups are born, but before pups begin to spend significant time in the water. Some studies have reported dispersal of mother-pup pairs away from breeding beaches during the pupping season (July), which may influence survey results. Using a multistate mark-recapture model with state uncertainty, we estimated the amount of dispersal during the pupping season based on observations of permanently marked sea lions. Research was conducted at land-based observation sites on Marmot Island, Alaska, between 2000 and 2013. Both marked adult females with dependent pups and marked pups were observed at two rookery beaches from May to July. Cumulative dispersal rates were minimal (< 1%) prior to the planned start of the aerial survey (23 June) and increased to 11.2% by the planned survey completion date (10 July). The increased cumulative dispersal rate during the remainder of the observation period (end of July) suggests potential bias in surveys that occur beyond 10 July, however surveys past this date are rare (< 10% between 1973 and 2016). As a result, movements of mother-pup pairs during the pupping season are not likely to influence aerial survey estimates.

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Environmental drivers of demography and potential factors limiting the recovery of an endangered marine top predator

et al. 2022

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Understanding what drives changes in wildlife demography is fundamental to the conservation and management of depleted or declining populations, though making inference about the intrinsic and extrinsic factors that influence survival and reproduction remains challenging. Here we use mark-resight data from 2000 to 2018 to examine the effects of environmental variability on age-specific survival and natality for the endangered western distinct population segment (wDPS) of Steller sea lions (Eumetopias jubatus) in Alaska, USA. Though this population has been studied extensively over the last four decades, the causes of divergent abundance trends that have been observed across the wDPS range remain unknown. We developed a Bayesian multievent mark-resight model that accounts for female reproductive state uncertainty. Annual survival probabilities for male pups (0.44; 0.36-0.53), female yearlings (0.63; 0.49-0.73), and male yearlings (0.62; 0.51-0.71) born in the western portion of the wDPS range, estimated here for the first time, were lower than those in the eastern portion of the wDPS range, estimated as: male pups (0.69; 0.65-0.74), female yearlings (0.76; 0.71-0.81), and male yearlings (0.71; 0.65-0.78). There was a higher proportion of young female breeders in the western portion of the range, but overall natality was lower (0.69; 0.47-0.96) than in the eastern portion of the range (0.80; 0.74-0.84). Additionally, pup mass had a positive effect on pup survival in the eastern portion of the range and a negative effect in the western portion of the range, potentially due to earlier weaning of heavier pups. Local-and basin-scale oceanographic features such as the Aleutian Low, the Arctic Oscillation Index, the North Pacific Gyre Oscillation, chlorophyll concentration, upwelling, and wind in certain seasons were correlated with vital rates. However, drawing strong inferences from these correlations is challenging given that relationships between ocean conditions and an adaptive top predator in a dynamic ecosystem are exceedingly complex. This study provides the first demographic rate estimates for the western portion of the range where abundance estimates continue to decline. These results will advance efforts to identify factors driving

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Environmental and biological factors influencing maternal attendance patterns of Steller sea lions (Eumetopias jubatus) in Russia

Cited by 21 publications

References 29 publications

Age Specific Survival Rates of Steller Sea Lions at Rookeries with Divergent Population Trends in the Russian Far East

Age Specific Survival Rates of Steller Sea Lions at Rookeries with Divergent Population Trends in the Russian Far East

Estimating dispersal rates of Steller sea lion (Eumetopias jubatus) mother-pup pairs from a natal rookery using mark-resight data

Environmental drivers of demography and potential factors limiting the recovery of an endangered marine top predator

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