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AHY HY ALL AHY HY MIG NM ALL 
Pueblo Vly. 
(7 to 24 Sep) 
Silver State Vly. 
(3 to 26 Oct) 
AHY HY MIG NM ALL 
Carson Sink 
(27 Oct to 10 Nov) 
RG ' 1 Box plots (25 and 75 percentiles: minimum and maximum) of use area (ha) by site and group, where AHY - 
Jdult, HY = hatch year, MIG = birds that departed on migration during the study, NM = birds that did not depart on 
Nigration during the study, and ALL = all birds. Number of birds in each group is displayed above each bar. 
across all sites; median area used by individuals 
14.0 ha (range = 1.3-1,436 ha) during 
observation periods ranging from 3 to 18 days 
" nd there was no relationship between days of 
Enervation and range size (r 7 = 0.04). Median 
“ rea us ed increased as the migratory season 
progressed (Pueblo Valley =3.9 ha; Silver State 
VaUe y = 16.8 ha; Carson Sink = 17.6 ha) 
1 •• median area used was greater among HY 
M7 - 5 ha) than AHY birds (9.7 ha) across all sites. 
0nc bird at the Carson Sink site used an area 
1.400 ha during 10 days of observation. This 
was captured on 29 October, and by 6 
November had moved 11 km south of its capture 
location. On the morning of 7 November, the bird 
ni0Ve d 7.8 km farther south, only to return 7.8 km 
"°nh by the afternoon to finish the day within 
m of where it had roosted the day prior. The 
hird moved no more than 500 m from the area 
0Ver the next 3 days. 
Migration Departures .—Eighteen of 38 radio- 
marked birds departed the study site during our 
observation period. We did not include one bird 
that departed within 2 days of capture because of 
possible stress-induced behavior or because it 
may have been an itinerant migrant. Only one bird 
departed during 165 bird-nights (35 individual 
birds monitored during 55 nights) of night-time 
observation with data-logging receivers; time of 
departure was ~~2 min prior to end of civil 
tw'ilight. All other departures occurred at un¬ 
known times on 10 days during the period 7 
September to 9 November; the first departure was 
on 13 October and last on 9 November. Five of 18 
departures occurred on one day (18 Oct ). 
The first three PCA axes explained 87% of the 
variation in the variables describing weather 
conditions on the 10 days that birds departed 
from study areas (Table 1). The first principal 
component represented warmer, windier, and 
