Maternal Behavior in Otariids and the Walrus

Sepúlveda, Maritza; Harcourt, Robert

doi:10.1007/978-3-030-59184-7_3

Cited by 4 publications

(4 citation statements)

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“…A 423-day gestation (or ~ 14 month) is consistent with an offset between the breeding season or observed conceptions and birth, whereby peak conceptions occurred in March (ranging from February to June) and with peak births in May (ranging from April to June). A 14-month gestation length is less than the 15 to 16 month period that was originally predicted by Fay [ 3 , 18 , 49 ]. Differences between our and Fay’s estimates appear to be related to our approximate 10-month post-diapause development phases versus Fay’s (1982) prediction of an 11-to-12-month period.…”

Section: Discussionmentioning

confidence: 93%

Growth, maturity, reproduction, and life expectancy in ex-situ pacific walruses (Odobenus rosmarus divergens)

Robeck¹,

Katsumata²,

Arai³

et al. 2022

BMC Zool

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Background Pacific walruses are found in Arctic regions of the Chukchi and Bering Sea where rapid changes in environmental conditions resulting in loss of sea ice are occurring. Therefore, accurate life history data are crucial for species management plans and longitudinal data collected over the lives of individual walruses housed in zoos and aquaria provide otherwise difficult to obtain biological information. Results While similar at birth, Gompertz regression curves indicated that males grew faster than females (p < 0.0001) in weight (99 kg vs 57.6 kg/y) and length (26.9 cm vs 26.3 cm/y) with physical differences being detected by age 3 for weight and age 7 for length. Males reached adult weight at 13.5 ± 3.3 y and females by age 12.3 ± 2.3 y. The mean age at first ovulation and at first conception occurred at 8.8 y and 9.6 y. Greater than 75% of all conceptions and calving occurred between February and March and from May to June, respectively. Mean gestation lasted 423 d and false pregnancies lasted at least 169 d with a decrease (p < 0.05) in serum progesterone concentration between false pregnancy and pregnancy occurring within 6 months after ovulation. Based on these results, we estimated embryonic diapause to last from 120 to 139 days, and fetal growth last ~ 284 days. All males older than 8 y had an increase in serum testosterone and body weight that was highest in February and lowest in July. Overall, no differences were observed between male and female survival, with a mean (± SEM) life expectancy of 19.5 ± 1.5 y, respectively. Currently, the oldest male and female captive walruses are 40 and 43 y, respectively. Conclusions Data provided herein include details of life history characteristics of zoo and aquaria housed walruses that are useful for wild population recovery models. In particular, results on survivorship and the identification of the most vulnerable period for calf survival can help with model development and suggests that for recovery to occur birthing locations for this species must be protected.

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Section: Discussionmentioning

confidence: 93%

Growth, maturity, reproduction, and life expectancy in ex-situ pacific walruses (Odobenus rosmarus divergens)

Robeck¹,

Katsumata²,

Arai³

et al. 2022

BMC Zool

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“…The aquatic lactation strategy utilized by walrus, sirenians, and dolphins is the most similar to the terrestrial “carry” strategy where the offspring remain in close proximity to the cow with nursing on demand that is initiated by the offspring. This provisioning strategy often lasts for multiple years and affords the opportunity for significant maternal investment for lactation and social learning ( Noren et al, 2014 ; Mann, 2019 ; Sepúlveda and Harcourt, 2021 ). Walruses are the only pinniped species that exhibit this strategy; nursing on demand for more than 2 years ( Schulz and Bowen, 2004 ).…”

Section: Behavioral Ecology—lactation Strategymentioning

confidence: 99%

“…While twinning is rare (>0.4% of all births) in pinnipeds since most species give birth to one pup per year, twinning has been genetically confirmed in walrus, Weddell seals, southern elephant seals, and Antarctic fur seals ( Gelatt et al, 2001 ; Hoffman and Forcada, 2009 ). More commonly, observations of females nursing more than one pup is due to fostering (also termed adoptive suckling, allosuckling, or allonursing) by the female or milk-stealing initiated by a nonfilial pup ( Sepúlveda and Harcourt, 2021 ). While true fostering until weaning is uncommon, milk-stealing occurs frequently among both otariids and phocids with obvious nutritional benefits to the nonfilial pup, although very risky due to aggressive retaliation from both the female and conspecific pup ( Sepúlveda and Harcourt, 2021 ).…”

Section: Dam/cow Duration Of Lactationmentioning

confidence: 99%

“…More commonly, observations of females nursing more than one pup is due to fostering (also termed adoptive suckling, allosuckling, or allonursing) by the female or milk-stealing initiated by a nonfilial pup ( Sepúlveda and Harcourt, 2021 ). While true fostering until weaning is uncommon, milk-stealing occurs frequently among both otariids and phocids with obvious nutritional benefits to the nonfilial pup, although very risky due to aggressive retaliation from both the female and conspecific pup ( Sepúlveda and Harcourt, 2021 ). Negative impacts of fostering on the adult female and her pup are observed with extended duration of lactation ( Civil et al, 2021 ).…”

Section: Dam/cow Duration Of Lactationmentioning

confidence: 99%

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