Table 1.

Information about moult surveys during 2013–2016, including quartiles for pupping dates and mean ± standard deviation moult initiation dates for each year and reproductive category.

	2013	2014	2015	2016
Sighting Metadata
# Sightings	1810	1470	2212	3423
# Seals	1038	866	937	1411
# Survey Days	19	10	11	26
First Moult Survey Date	Jan 13	Jan 17	Jan 18	Jan 18
Last Moult Survey Date	Feb 13	Feb 14	Feb 15	Mar 8
Pupping Quartiles
Minimum	*	Oct 11	Oct 13	Oct 14
25th percentile	*	Oct 22	Oct 22	Oct 24
Median	Oct 29	Oct 26	Oct 27	Oct 28
75th percentile	Nov 02	Oct 30	Oct 30	Nov 02
Maximum	Nov 15	Nov 26	Nov 13	Nov 19
Moult Initiation Dates
Attendant Non-Parturient	Dec 28 ± 11.9i	Jan 05 ± 10.7ii	Jan 07 ± 9.9ii	Jan 12 ± 9.8iii
Non-Attendant Juvenile Females	Jan 06 ± 11.6i	Jan 07 ± 13.7i	Jan 11 ± 9.7i	Jan 17 ± 12.1ii
Attendant Juvenile Females	Jan 04 ± 11.3i	Jan 11 ± 6.7ii	Jan 15 ± 8.3ii	Jan 15 ± 14.6ii
Non-Attendant Adult Females	Jan 07 ± 14.5i	Jan 11 ± 11.8i	Jan 17 ± 11.7i	Jan 19 ± 9.6i
Attendant Parturient	Jan 19 ± 8.4i	Jan 15 ± 11.1ii	Jan 18 ± 9.2i	Jan 29 ± 13.2iii
Males	Jan 09 ± 13.1i	Jan 13 ± 10.6ii	Jan 16 ± 8.1ii	Jan 24 ± 12.9iii
Ice break-out date**	Jan 14	Jan 14	Jan 02	Feb 04
Colony attendance***
Attendant Non-Parturient	22%	22%	18%	25%
Non-Attendant Parous	10%	6%	22%	20%
Attendant Parturient	68%	72%	60%	55%

Significant differences in moult initiation dates among years (by row, within a reproductive category) are denoted with Roman numerals (α level = 0.05).

*In 2013, the United States government shut down delayed the Weddell seal research program by several weeks, and pup tagging began only after 50% of the pups were born; as a result, the dates of the earlier quartiles are not known (see methods).

**Date when 7-day running mean of ice concentration falls below 50%. See Beltran⁴² for details.

***Colony attendance proportions for the following year.