Shortening migration by 4500 km does not affect nesting phenology or increase nest success for black brant (Branta bernicla nigricans) breeding in Arctic and subarctic Alaska

Table 2 Migration phenology of Pacific black brant (Branta bernicla nigricans) based on light-level geolocators

Season	Wintering site	Event	Arctic-breeding	n	Subarctic-breeding	n
Breeding	–	Departure	Aug 15 (Aug 6–Aug 24)	33	Aug 1 (Jul 22–Aug 10)	31
Fall (Izembek)	–	Arrival	Sep 23 (Sep 14–Oct 3)	33	Sep 11 (Sep 2–Sep 21)	31
Fall (Izembek)	–	Departure	Oct 20 (Oct 9–Oct 30)	21	Oct 16 (Oct 7–Oct 26)	27
Winter	Izembek	Arrival	Sep 13 (Sep 5–Sep 20)	9	Sep 6 (Aug 23–Sep 19)	3
	Izembek	Departure	May 13 (Apr 27–May 30)	8	Apr 29 (Apr 5–May 25)	3
	Mexico	Arrival	Nov 19 (Nov 13–Nov 25)	21	Nov 14 (Nov 8–Nov 19)	27
	Mexico	Departure	Mar 14 (Feb 28–Mar 27)	20	Mar 22 (Mar 11–Apr 2)	27
Spring (Izembek)	Mexico	Arrival	May 5 (Apr 28–May 11)	16	Apr 23 (Apr 18–Apr 28)	21
Spring (Izembek)	Mexico	Departure	May 31 (May 27–Jun 4)	16	May 22 (May 19–May 25)	21
Breeding	Izembek	Arrival	May 28 (May 21–Jun 4)	7	May 17 (May 6–May 29)	3
	Izembek	Incubation	Jun 10 (Jun 6–Jun 14)	8	May 28 (May 20–Jun 4)	2
	Mexico	Arrival	Jun 1 (May 27–Jun 8)	16	May 19 (May 14–May 24)	27
	Mexico	Incubation	Jun 10 (Jun 7–Jun 13)	11	Jun 1 (May 30–Jun 4)	23

Median departure and arrival dates at breeding sites, wintering sites, and fall/spring migratory stopovers for black brant (brant) from subarctic (Tutakoke River; 61.3° N, 165.6° W) and Arctic breeding sites (Colville River Delta; 70.42° N, 150.38° W) in Alaska, USA. Izembek Lagoon (Izembek) is used as a fall staging area by most brant, but it is also used as a wintering site or spring staging area. Winter arrival and departure dates are also shown for wintering habitat in Baja California, Mexico (Mexico). Brant that overwintered at Izembek were not used to calculate fall departure dates or spring arrival dates for Izembek. Arrival and departure dates were estimated using Bayesian mixed models with fixed effects: wintering site*breeding site and a random effect of year. 95% posterior credible intervals are in parentheses. n = sample size

ISSN: 2051-3933