Weaning mass and the future survival of juvenile southern elephant seals, <i>Mirounga leonina</i>, at Macquarie Island

McMahon, Clive R.; Burton, Harry R.; Bester, Marthán N

doi:10.1017/s0954102000000195

Cited by 175 publications

(209 citation statements)

References 27 publications

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“…Relying only on coastal, benthic prey of poor nutritional quality will be useful to reduce the foraging trip length and hence the pup mortality during early lactation. However, this foraging strategy will negatively affect the pup growth rate and may increase the mortality rate at weaning if the weight at weaning correlates with the survival rate, as reported for other pinnipeds (McMahon et al, 2000).…”

Section: Discussionmentioning

confidence: 87%

Change in the foraging strategy of female South American sea lions (Carnivora: Pinnipedia) after parturition

Drago¹,

Cardona²,

Crespo³

et al. 2010

Sci. Mar.

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SUMMARY: This study tests the hypothesis that female South American sea lions shift from off-shore, pelagic prey to coastal, benthic prey after parturition in order to reduce the foraging trip duration and hence the time pups remain unattended on the beach during early lactation. The δ 13 C and δ 15 N values of the serum and blood cells of 26 South American sea lion suckling pups from northern Patagonia were used to track the dietary changes of their mothers from late pregnancy to early lactation, after correction for differential isotopic fractionation between tissues. Primary producers and potential prey species were also analysed to establish a baseline for interpreting the stable isotope concentration of serum and blood cells. Isotopic ratios revealed a generalized increase in the consumption of coastal-benthic prey after parturition. Such a generalized postpartum shift will allow females to spend more time on land and look after their pups. The effects of this foraging strategy on the nutritional quality of the female's diet are discussed.Keywords: South American sea lion, diet, feeding strategy, suckling pup, lactating females, Otaria flavescens, stable isotopes, Bayesian mixing models. RESUMEN: Cambio en la estrategia de alimentación de las hembras del león marino sudamericano (Carnivora: Pinnipedia) tras el parto. -El presente estudio pretende comprobar si las hembras del león marino sudamericano adoptan una dieta más bentónica y costera tras el parto, con el fin de reducir la duración de los viajes de alimentación y reducir así el tiempo durante el cual las crías permanecen desatendidas en la playa. Para ello, se determinaron las concentraciones de isótopos estables de carbono y nitrógeno en el suero y las células sanguíneas de 26 crías lactantes de león marino sudamericano del norte de la Patagonia, con el fin de reconstruir la dieta de la madre durante la parte final de la gestación y el inicio de la lactancia, tras la correspondiente corrección del fraccionamiento isotópico entre tejidos. También se analizaron muestras de productores primarios y de presas potenciales para ayudar en la interpretación de los resultados. Las concentraciones de isótopos estables antes y después del parto confirmaron un incremento en el consumo de presas bentónicas costeras tras el parto. Este cambio generalizado de dieta tras el parto permitiría a las hembras incrementar el tiempo que pasan junto a las crías. Se discuten los efectos que esta estrategia puede tener sobre la calidad de la dieta de las hembras.Palabras clave: león marino sudamericano, dieta, estrategias tróficas, lactancia, Otaria flavescens, isótopos estables, modelos de mezcla bayesianos.

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Section: Discussionmentioning

confidence: 87%

Change in the foraging strategy of female South American sea lions (Carnivora: Pinnipedia) after parturition

Drago¹,

Cardona²,

Crespo³

et al. 2010

Sci. Mar.

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“…For small weanlings, . Given that an extra 5 kg may sustain a fasting pup for 10 days at sea [19], this difference is biologically significant. Females foraging at high (inferred from smaller d 13 C values) or low (inferred from larger d 13 C values) latitudes, had a greater probability of weaning a large pup than females foraging in the interfrontal zone (figure 2a and electronic supplementary material, figure S1).…”

Section: Results (A) Stable Isotopesmentioning

confidence: 99%

“…McMahon et al [19] found a positive relationship between a pup post-weaning survival and its weaning mass: females that have stored and transferred more energy to their pup prior to the spring haul-out had a larger reproductive fitness. Because any changes in patterns of maternal foraging strategies may affect pup survival, we assessed the effect of maternal foraging strategies on pup fitness by studying the relationships between pup weaning mass and blood isotope ratio.…”

Section: Introductionmentioning

confidence: 99%

O' mother where wert thou? Maternal strategies in the southern elephant seal: a stable isotope investigation

et al. 2012

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Maternal effects are widespread in ecology and can alter the dynamics of a population. We investigated the impact of maternal foraging strategies on offspring weaning mass-a proxy of maternal foraging success and of offspring survival-in southern elephant seals on îles Kerguelen. Using 4 years of data, we modelled pup weaning mass as a two-component mixture and used blood stable isotope values to discriminate between maternal foraging strategies previously identified from bio-logging studies. Carbon isotope ratio was a strong predictor of weaning mass, but the relationship was non-monotonic in contrast to a priori expectations. Females foraging in the interfrontal zone weaned pups with a smaller mass compared with females foraging in Antarctic waters. Pup mass was positively correlated with a proxy of global primary production in the interfrontal zone for small weanlings. Maternal effects, via a poor foraging efficiency in the 1970s, may help explain the large population decrease observed at that time on îles Kerguelen because of an overall decrease in pup weaning mass, survival and subsequent recruitment.

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“…Body size is a strong predictor of infant and juvenile survival in a wide range of animals, including some lizards (80), fish (81), birds (82,83), rodents (84,85), pinnipeds (86,87), deer (88,89), and primates (90). Although these effects are often attributable to predation, similar effects are seen in humans, for which both low birthweight and poor growth compromise long-term health and well-being (91)(92)(93)(94).…”

Section: Discussionmentioning

confidence: 99%

Faster reproductive rates trade off against offspring growth in wild chimpanzees

Thompson

Muller

Sabbi

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Life history theory predicts a trade-off between offspring quality and quantity. Among large-bodied mammals, prolonged lactation and infant dependence suggest particularly strong potential for a qualityquantity trade-off to exist. Humans are one of the only such species to have been examined, providing mixed evidence under a peculiar set of circumstances, including extensive nutritional provisioning by nonmothers and extrasomatic wealth transmission. Here, we examine trade-offs between reproductive rate and one aspect of offspring quality (body size) in wild chimpanzees (Pan troglodytes schweinfurthii), a species with long periods of infant dependence and little direct provisioning. Juvenile lean body mass, estimated using urinary creatinine excretion, was positively associated with the interval to the next sibling's birth. These effects persisted into adolescence and were not moderated by maternal identity. Maternal depletion could not explain poor offspring growth, as older mothers had larger offspring, and low maternal energy balance during lactation predicted larger, not smaller, juvenile size. Instead, our data suggest that offspring growth suffers when mothers wean early to invest in new reproductive efforts. These findings indicate that chimpanzee mothers with the resources to do so prioritize production of new offspring over prolonged investment in current offspring.life history | growth | reproduction | primates | weaning P arents face a fundamental life-history trade-off between producing more offspring and investing in the quality of each progeny (1-4). This offspring quality-quantity trade-off, along with a trade-off between reproductive investment and parental survival, means that maximizing reproductive rates is often not the strategy that maximizes fitness (5-7). The quality-quantity trade-off has been empirically demonstrated in species that produce litters or clutches, where large litter size often leads to small offspring size, slow growth rates, and reduced survival, particularly under conditions of ecological stress (8-11). Comparative analyses also support a negative interspecific relationship between reproductive rate and offspring size (12, 13). The quality-quantity trade-off has rarely been examined in species for which single births are the norm, and for which reproductive rate is determined by the interval between successive births. Such species are important tests of the model, as a slow breeding strategy suggests a particularly potent trade-off between offspring investment and reproductive rate. Understanding how individuals negotiate this trade-off can provide important insights into the evolution of reproductive biology and behavior.Data on humans are valuable because humans invest intensively in offspring, yet have highly variable reproductive rates. Many studies find the predicted negative relationship between reproductive rates and offspring growth or health (14-18) or demonstrate fitness maximization at intermediate levels of fertility (19-21). For example, when a water tap was ...

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Weaning mass and the future survival of juvenile southern elephant seals, Mirounga leonina, at Macquarie Island

Cited by 175 publications

References 27 publications

Change in the foraging strategy of female South American sea lions (Carnivora: Pinnipedia) after parturition

Change in the foraging strategy of female South American sea lions (Carnivora: Pinnipedia) after parturition

O' mother where wert thou? Maternal strategies in the southern elephant seal: a stable isotope investigation

Faster reproductive rates trade off against offspring growth in wild chimpanzees

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