Short Communications 
The Wilson Journal of Ornithology 123(4):803-807, 2011 
Seasonal Movements and Environmental Triggers to Fall Migration of 
Sage Sparrows 
Kurt A. Fesenmyer 1-2 and Steven T. Knick 1,3 
ABSTRACT.—Post-breeding ecology of shrubland 
passerines prior to onset of migration is unknown 
relative to dynamics of breeding areas. Wc radtomarkcd 
and monitored 38 Sage Sparrows (Amphispiza belli ssp. 
nevadensis) at one site in Oregon and two in Nevada 
from September to mid-November 2007 to track local 
movements, estimate seasonal range sizes, anti charac¬ 
terise weather patterns triggering onset of migration, 
Median area used by Sage Sparrows monitored between 
3 and 18 days during or prior to migration was 14 ha; 
maximum daily movement was IS km. Radio-marked 
Sage Sparrows at each location departed individually, 
rather than en masse, corresponding with passage of 
cold front weather systems. Conventional telemetry 
techniques limited our ability to monitor Sage Sparrows 
beyond pre-migratory periods and precluded detecting 
and tracking actual movements during migration. 
Received 13 December 20JO. Accepted 20 May 2011. 
Sage Sparrows (Amphispiza belli ssp. nevaden- 
sis) are a species of conservation concern across 
their range, primarily due to loss of sagebrush 
'^nemisia spp.) habitats on which they depend 
'knick and Rotenberry 2002). Habitat loss, 
fragmentation, and degradation associated with 
invasive annual grasses and altered fire regimes in 
breeding areas may be the most significant factors 
influencing long-term and regional population 
dynamics of Sage Sparrows (Knick et al. 2003). 
However, environmental stresses in the non- 
hreeding period, particularly those prior to, 
during, and after migration also may be important 
(Fretwell 1972. Sillett and Holmes 2002). Move¬ 
ments and habitat use during post-breeding and 
migration are relatively unknown for most 
shrubsteppe passerines during the non-breeding 
Period (Swarth 1924. Moyer 1933, Littlefield 
1990). 
0-S Geological Survey, Forest and Rangeland Ecosys- 
,em Science Center. Snake River Field Station. 970 Lusk 
s 'reci. Boise. ID 83706. USA. 
Current address: Trout Unlimited. National Science and 
Technology Center, 910 West Main Street, Suite 342. 
B msc, ID 83702. USA. 
'Corresponding author; e-mail: steve_knick@usgs.gov 
Radiotclcmetry has been an important tech¬ 
nique to study habitat use and movements of 
larger passerine birds during migration (Cochran 
1987, Schaub et al. 2004). We expected recent 
advances in battery' size reduction and signal 
strength of radio transmitters would permit similar 
application to small passerines <25 g (Thorup et 
al. 2007, Paxton et al. 2008), such as Sage 
Sparrows. Our objectives were to: (l) track Sage 
Sparrows during the fall migratory period to 
describe movements. (2) estimate seasonal range 
sizes, and (3) identify weather characteristics that 
prompt migration. 
METHODS 
We surveyed 18 randomly-selected 1-km tran¬ 
sects in shrublands of the northern Great Basin 
during early September 2007 to identify regions 
and general habitats used by pre-migratory Sage 
Sparrows. Transects were within contiguous 
patches of uniform habitat types based on exist¬ 
ing vegetation type classifications (LANDFIRE 
2006). We assessed habitats varying in produc¬ 
tivity and disturbance that ranged from cheatgrass 
(Brotnus tectorum) grasslands at low elevations to 
low-density pinyon ( Finns spp.) and juniper 
(Juniperus spp.) woodlands at upper elevations 
of shrubland distributions. We observed Sage 
Sparrows on only six transects, including three in 
Wyoming big sagebrush (Artemisia iridentata ssp. 
wyomingensis) and three in black greasewood 
(Sarcobatus vermiculalus). Greatest concentra¬ 
tions of Sage Sparrows occurred in locally 
productive shrublands (i.e,, those with greener 
foliage and higher seed production) dominated by 
greasewood along alluvial draws and adjacent to 
playas. 
We used these gross characteristics to select 
three study sites within north-south-oriented 
valleys: Pueblo Valley. Oregon (42 00' N, 118 
36' W; 7 to 24 Sep); Silver State Valley, Nevada 
(4 V 2Y N, 117 53' W; 3 to 26 Oct); and Carson 
Sink, Nevada (39 54' N, 118 14' W; 27 Oct to 
10 Nov). We hypothesized that north-south- 
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