DOI: 10.7291/d1c10c
title: Data for: Molt timing and duration of northern elephant seals

description: Life history timing influences many ecosystem processes including
 predator-prey interactions, information transfer, disease transmission,
 ecosystem services, and resource subsidies. Many animals and plants have
 species-typical annual cycles, but individuals vary in their exact timing
 of life history events. However, quantifying individual variation in the
 timing and duration of life history events requires longitudinal sampling
 and may necessitate advanced analytical techniques if observations are
 imperfect or asynchrony is prevalent. Our goal was to examine factors that
 influence variation in molt duration and timing across individual northern
 elephant seals (Mirounga angustirostris). We quantified the onset and
 progression of fur loss in 1,178 individual seals over seven years. We
 found a wide range of molt start dates (95% interval spanning 60.1 days
 within a single age-sex category) and rapid molt progression (6.0 days in
 adult females and 10.8 and 10.3 days in juvenile females and males,
 respectively) with high molt asynchrony (only 20% of individuals in the
 population molting at the same time). Individual variation in the timing
 of the molt within age-sex categories was much larger than between
 categories: 94% of the variation in haul-out duration, 74% of variation in
 molt start date, and 59% of variation in molt duration was among
 individuals within age-sex categories. Finally, we discovered that
 individuals arriving late for the molt spent less time on the beach than
 earlier arrivers, which allowed them to catch up if they fell behind in
 their annual cycles. These findings emphasize the importance of
 quantifying individual variation in critical life history events.
description: # Molt timing and duration of northern elephant seals --- Six .csv files
 contain processed data (each row is a year-seal combination), and one .r
 file contains the code to fit the models and reproduce the figures. ##
 Description of the Data and file structure *Headers in the
 "MoltMSFinal.csv" file are as follows:* X = unique
 year-identifier for each seal age = animal age, years N = number of
 observations for that year-seal best = molt date (50% progress), days
 since January 01 slope = molt duration (days) card = if a number is
 present, the female had a pup during the breeding season sex = male or
 female arrival = modeled arrival date, days since January 01 departure =
 modeled departure date, days since January 01 tenure = haul-out duration,
 days agesexcat = age-sex category *Headers in the
 "MoltMSFinalModelOut.csv" file are as follows:* graphx = date,
 days since January 01 pred1 = model fit (predicted molt progress, %)
 *Headers in the "MoltMSFinalCircular.csv" file are as follows:*
 Season = life history event (categorical) Q50 = median population-level
 timing (date) *Headers in the "MoltMSFinalCircularSD.csv" file
 are as follows:* Season = life history event (categorical) SD = standard
 deviation population-level timing (days) *Headers in the
 "MoltMSFinalAnnot.csv" file are as follows:* x = date location
 for annotation labels y = y location for annotation labels *Headers in the
 "MoltMSFinalOut.csv" file are as follows:* yday = yearday of
 observation (days since January 1) molt = percent of new fur on the body
 Please note that "NA" in cells mean that no data were observed.
 --- The "eseal_molt_AppFigs 2024_02_13.pdf" file contains
 supplemental tables and appendices.