Birth timing after the long feeding migration in northern elephant seals
Creators
- 1. University of California, Santa Cruz
- 2. Sonoma State University
Description
A prominent phase of the annual cyle in migratory animals is the transition between migration and reproduction. The transition is a small part of the annual cycle, but details of its timing deserve attention. From a distant location, animals must initiate a long migration so that they arrive at the breeding ground on a precise schedule. Here we take advantage of a sample of female northern elephant seals that were tracked by satellite during their migration prior to parturition. In these animals, we could estimate the time interval between arrival and birth, allowing tests of the following hypotheses: 1) More experienced mothers could time arrival more precisely and thus reduce the pre-parturition interval. 2) Mothers in poor body condition were forced to forage longer and thus shorten the interval. 3) Late-arriving mothers had a shorter interval because they foraged longer. We also calculated the distance traveled in the last two weeks of the migration to examine females' ability to control arrival time, hypothesizing that animals further from the colony traveled back at a higher speed.
Notes
The table includes observations from 106 female migrations ending at the Año Nuevo colony in California. It is tab-delimited ascii. The columns are:
- animalID: Unique individual identifier
- season: Year of birth (arrival dates were in Dec of previous year in several cases)
- age: Age of female in years (85 of the records have age)
- adate: Arrival date, Year-month-day format
- aday: Arrival day (days since 1 December of the year before season)
- firstwith: First day with a pup (days since 1 December)
- dist15: Distance from colony (km) 15 days prior to birth (99 of the records have distances)
- dist10: Distance from colony (km) 10 days prior to birth
- dist5: Distance from colony (km) 5 days prior to birth
- distmax: Maximum distance from colony (km) during entire migration prior to birth
Funding provided by: Office of Academic Research, U.S. Naval Academy
Crossref Funder Registry ID: http://dx.doi.org/10.13039/100015089
Award Number: N00014-00-1-0880, N00014-03-1-0651, N00014-08-1-1195, N00014-10-1-0356
Funding provided by: Ocean Partnership Programme*
Crossref Funder Registry ID:
Award Number: N00014-02-1-1012
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