Sex differences in mass loss rate and growth efficiency in Antarctic fur seal ( Arctocephalus gazella ) pups at Macquarie Island

Guinet, Christophe; Goldsworthy, Simon; Robinson, Sue

doi:10.1007/s002650050605

Cited by 45 publications

(32 citation statements)

References 32 publications

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“…The pup was recaptured and weighed 24 to 48 h after the female departed on her first foraging trip, to obtain a post-perinatal mass. Waiting 24 to 48 h after female departure ensured that the pup had digested the milk and provided a more accurate mass (Guinet et al 1999). Pups were again captured 24 to 48 h after their mother departed on her 7th foraging trip.…”

Section: Methodsmentioning

confidence: 99%

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Effects of maternal traits and individual behavior on the foraging strategies and provisioning rates of an income breeder, the Antarctic fur seal

McDonald

Goebel²,

Crocker³

et al. 2009

Mar. Ecol. Prog. Ser.

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The ability of an animal to acquire energy will affect its allocation to offspring and will ultimately influence fitness. This study investigated the relative influence of maternal traits, seasonal demands of pup-rearing, and individual effects on the foraging behavior of 27 female Antarctic fur seals Arctocephalus gazella at Cape Shirreff, Livingston Island, Antarctica during 2 austral summers (2005 and 2006), using time depth recorders. The relationship between foraging and allocation was investigated using pup growth as an indicator of parental investment. While female diving behavior differed between years, trip duration was below the 10 yr mean and did not differ between the 2 years of the study, indicating favorable feeding conditions in both years. Study year and maternal age accounted for a significant amount of the variation in day and night dive characteristics, while maternal mass influenced only parameters related to night dive effort. As the season progressed, females increased their dive effort at night, made shorter daytime dives, with more bout diving. Individual variability accounted for a significant amount of the variation in all foraging parameters. Females could be assigned to one of 4 behavioral dive groups (high effort, low effort, intermediate effort with high dive rate, and intermediate effort), based on 13 dive parameters although year instrumented and age appeared to be important in determining group affiliation. Age, mass, year, and trip number influenced diving behavior; however, there was no relationship between foraging behavior and pup growth rate, except in young females. KEY WORDS: Diving behavior · Energy allocation · Individual effects · Pinniped · Antarctic fur seal Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 394: [277][278][279][280][281][282][283][284][285][286][287][288] 2009 ashore nursing their pup. Otariids are required to return regularly to the breeding site to feed their young and are, thus, defined as central place foragers (Orians & Pearson 1979). As such, otariids are restricted in the distance they can travel and time they can spend foraging by the physiological demands of the pup. Mothers should optimize their foraging behavior in order to maximize the rate of food delivery to their young.Individual traits such as age, mass, and condition often influence foraging behavior. Foraging efficiency (energy gained per unit effort) increases with age and experience in many species (Galbraith et al. 1999, Daunt et al. 2007, Skorka & Wojcik 2008, potentially because an individual's ability to find and handle prey improves with experience (Orians 1981, Galbraith et al. 1999. In central place foragers, experience may influence the point at which the individual decides to return to their offspring. Body mass may also play an important role in foraging behavior. In diving vertebrates, mass can affect breath hold capacity and thus diving behavior (Schreer & Kovacs 1997). Larger size is also beneficial because it ...

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Section: Methodsmentioning

confidence: 99%

“…However, pup growth rate may be affected by factors other than maternal investment, such as weather and individual differences in pup physiology and/or behavior (Guinet et al 1999, Donohue et al 2002, Arnould et al 2003. Milk intake measurements could provide a better index of maternal investment (Arnould et al 1996a).…”

Section: Maternal Investmentmentioning

confidence: 99%

Effects of maternal traits and individual behavior on the foraging strategies and provisioning rates of an income breeder, the Antarctic fur seal

McDonald

Goebel²,

Crocker³

et al. 2009

Mar. Ecol. Prog. Ser.

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“…Although the sample sizes are small, the data presented here indicate that this is also the case at Marion Island. The disparity between an even sex ratio at birth and a male bias at one to two months of age can only be due to greater female mortality in the first few weeks of life (De Villiers & Roux 1992;Guinet et al 1999;. Male fur seal pups are larger than females on average (Payne 1979;Doidge et al 1984b;Kerley 1985;Bester 1987;Bester & Van Jaarsveld 1994).…”

Section: Sex Ratiomentioning

confidence: 99%

“…Male and female pups follow different growth strategies (Guinet et al 2000;Arnould et al 2001;Georges & Guinet 2001) with male pups both being heavier at birth and having higher growth rates, and therefore requiring greater food resources (Guinet et al 2000;. The limited food resources provided by mothers during poor years may therefore have a greater effect on male than on female survival, resulting either in an even sex-ratio, or one favouring female pups (Guinet et al 1999; (Kirkman et al 2002;Leach 2003). While it is possible that the conditions to which fur seal pups are subjected to at Marion Island do not lead to greater female mortality, reasons for the parity in pup sex ratio are, at present, unknown.…”

Section: Sex Ratiomentioning

confidence: 99%

“…Amongst the most essential data are those related to pups. This age class experiences highly variable rates of mortality (Doidge et al 1984a;Fowler 1990;Harcourt 1992;Majluf 1992), which are often influenced by sex (De Villiers & Roux 1992;Guinet et al 1999;Bradshaw et al 2003; and timing of parturition (Lunn & Boyd 1993;Lunn et al 1994). Mortality of this age class is possibly more important than that of any other in determining the size of a cohort at breeding age, with mortality reaching close to one hundred percent in some years for some populations (Trillmich 1985;Roux 1998;Soto & Arias-Schreiber 2004).…”

Section: Introductionmentioning

confidence: 99%

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Median pupping date, pup mortality and sex ratio of fur seals at Marion Island

Hofmeyr¹,

Bester²,

Pistorius³

et al. 2007

South African Journal of Wildlife Research

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Modelling fur seal populations requires the accurate assessment of demographic parameters such as age-specific mortality. Owing to the highly variable mortality rates that pups are subject to, mortality of this age class is perhaps the most important factor determining the number of surviving individuals within each cohort. Early pup mortality, sex ratio and median pupping date were determined for sympatric populations of Subantarctic fur seals (Arctocephalus tropicalis) and Antarctic fur seals (A. gazella) at Marion Island, Southern Ocean. Mortality for this species was density dependent, varying from 0.8% at low density sites to 10.9% at high density sites. More accurate methods employed at low-density sites showed a substantially higher pup mortality at three weeks of 1.3-3.4% for Subantarctic fur seals. The same method yielded a mortality estimate at four weeks of age of 1.1-5.1% for Antarctic fur seals. Despite the underestimate inherent in island-wide counts for Subantarctic fur seals, these estimates are still useful for observing temporal and spatial patterns. Sex ratios were at parity for newborns of both species. The sex ratio of eightweek-old Subantarctic fur seal pups was also at parity, which is unusual for fur seal populations. The median pupping dates determined for Subantarctic fur seals and Antarctic fur seals did not differ substantially from previous estimates.

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Richer milk for sons but more milk for daughters: Sex‐biased investment during lactation varies with maternal life history in rhesus macaques

Hinde

2009

American J Hum Biol

150

184

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Lactation represents the greatest postnatal energetic expenditure for human and non-human primate females, and the ability to sustain the costs of lactation is influenced by a mother's physical condition. This is especially true for young mothers that initiate reproduction shortly after adolescence. These mothers have fewer bodily reserves available for lactation and face tradeoffs between reproduction and their own growth. Milk synthesis among captive rhesus macaques (Macaca mulatta) was investigated at the California National Primate Research Center from 2005 to 2007 (N = 114). Rhesus macaques produced low energy density milk typical of the primate order, but there was substantial individual variation among mothers in both milk energy density and yield. As a consequence, the available milk energy (AME), the product of milk energy density and milk yield, to support infant growth, development, and activity, varied tenfold among mothers. Primiparous mothers (N = 40) had fewer bodily resources, as measured by mass and body mass index, available for lactation than did multiparous mothers (N = 74) and showed poorer lactational performance. Mothers of sons produced milk of higher energy density, especially primiparous mothers, but lower milk yield, such that AME was the same for sons and daughters. Although AME from the mother was the same for sons and daughters, there was significant sexual dimorphism in infant mass. These data indicate that selection has likely favored sex-specific regulation of growth and development that is not necessarily contingent on greater maternal investment.

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Sex differences in mass loss rate and growth efficiency in Antarctic fur seal ( Arctocephalus gazella ) pups at Macquarie Island

Cited by 45 publications

References 32 publications

Effects of maternal traits and individual behavior on the foraging strategies and provisioning rates of an income breeder, the Antarctic fur seal

Effects of maternal traits and individual behavior on the foraging strategies and provisioning rates of an income breeder, the Antarctic fur seal

Median pupping date, pup mortality and sex ratio of fur seals at Marion Island

Richer milk for sons but more milk for daughters: Sex‐biased investment during lactation varies with maternal life history in rhesus macaques

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