Data from: Density-dependent effects on reproductive output in a capital breeding carnivore, the northern elephant seal (Mirounga angustirostris) ...

• Main Authors: Costa, Daniel, Holser, Rachel, Crocker, Daniel, Robinson, Patrick, McDonald, Gitte, Fowler, Melinda, Hassrick, Jason, Hückstädt, Luis, Peterson, Sarah, Simmons, Samantha, Keates, Theresa
• Format: Dataset
• Language: English
• Published: Dryad 2021
• Subjects: Pinnipeds; Mammals; Lactation; life-history; Animals; environment; FOS Biological sciences; Elephant Seal
• Online Access: https://dx.doi.org/10.7291/d1k099; https://datadryad.org/stash/dataset/doi:10.7291/D1K099

All organisms face resource limitations that will ultimately restrict population growth, but the controlling mechanisms vary across ecosystems, taxa, and reproductive strategies. Using four decades of data, we examine how variation in the environment and population density affect reproductive outcomes in a capital-breeding carnivore, the northern elephant seal (Mirounga angustirostris). This species provides a unique opportunity to examine the relative importance of resource acquisition and density-dependence on breeding success. Capital breeders accrue resources over large temporal and spatial scales for use during an abbreviated reproductive period. This strategy may have evolved, in part, to confer resilience to short-term environmental variability. We observed density-dependent effects on both weaning mass and male-biased allocation of resources to offspring. Furthermore, maternal age (experience) was more important than oceanographic conditions or maternal mass in determining offspring weaning mass. ... : Adult female mass gain during the gestational (post-moult) foraging trip was measured in approximately 20 individuals per year from 2004 – 2019. Females were sedated a few days before departure at the end of the moulting fast and again upon return to shore during the breeding season, following standard protocols. These individuals were equipped with time-depth recorders (TDRs) and satellite transmitters (Wildlife Computers, Redmond, WA, USA or Sea Mammal Research Unit, St. Andrews, Scotland) that provided location information through the Argos network. At each handling, the animal was weighed in a canvas sling suspended from a hanging scale with a precision of ± 1 kg. During the breeding season, instruments were recovered on the fifth day following birth. During these procedures, the female’s pup was also weighed and flipper tagged. Additionally, adult females were sedated for physiological studies in 1991, 1992, 1995-1997, 2001-2006, and 2009. These procedures provided additional data on female arrival ...