Elephant seal female breeding histories at Año Nuevo
Creators
- 1. University of California, Santa Cruz
Description
The elephant seal (Mirounga angustirostris) breeding colony at Año Nuevo, California, was founded in 1961, and since monitored closely until the present. Since 1968 a research group at the University of California, Santa Cruz, has studied it in detail. Individually identified females were monitored during the breeding season, and pupping records of many throughout their lifetimes were assembled. We address here the maximum reproductive success of females using the lifetime breeding histories. Females lived to a maximum of 23 years and were observed breeding in as many as 17 seasons. One female was observed with a pup nearby in 16 consecutive seasons, from age 4 through age 19. We compared females that gave birth to 10 or more pups (Supermoms) with females that bred at least once but produced fewer than 10 pups (Generic moms). Less than 17% of female weanlings bred at least once. Only 0.87% of females in the sample became Supermoms. We conclude that exceptional reproductive success in elephant seals is associated with giving birth annually, living long and weaning pups successfully. Once female elephant seals begin reproducing they are pregnant or nursing throughout life until they die.
Notes
The dataset includes a single table with a single row for every breeding event of tagged females at the Año Nuevo colony. All breeding observations of a single female appear consecutively in the table in the default sorting. Full descriptions of the data can be found in the accompanying paper, cited below.
Users interested in publishing results with these data should consult the principal investigators to best understand details of the methods. Those PIs might request co-authorship on publications based largely on the data.
Column headings and definitions
- animalID: an arbitrary number identifying individuals
- year: the breeding season, including December of the previous year plus December-March of the designated year
- age: the female's age in years, blank for animals tagged as adults and thus of unknown age
- firstday: the first date observed
- lastday: the last date observed
- sightings: the number of days on which the female was observed
- sightpostpart: the number of days sighted beyond 6 days after the first sighting (assumed parturtion date)
- pup: the number of days on which the female was observed with one pup (with a pup but not two or more pups)
- puppostpart: the number of days observed with exactly one pup beyond 6 days after first sighting
- area: the main breeding beach, defined as one at which the female was seen most, or with a pup (local names at Año Nuevo)
- allarea: each area observed, with the number of observations at each
- birthregion: tagging colony for weanlings only (AN=Año Nuevo; all other designations are for colonies at least 100 km distant)
- birthyr: year of birth
- pupwt: weight in kilograms of the pup's weight at weaning
- success: fate of the pup (weaned_pup or lost pup; other designations indicate insufficient sightings)
- pupsex: observed pup sex
Funding provided by: National Science Foundation
Crossref Funder Registry ID: http://dx.doi.org/10.13039/100000001
Award Number:
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