J. Field Ornithol. 77(4):372–383, 2006
DOI: 10.1111/j.1557-9263.2006.00067.x
Community composition and migration chronology
of shorebirds using the saline lakes of the Southern
Great Plains, USA
Adrian E. Andrei,1,4 Loren M. Smith,1 David A. Haukos,2 and James G. Surles3
1
2
Department of Range, Wildlife, and Fisheries Management, Texas Tech University, Lubbock, Texas 79409, USA
U.S. Fish and Wildlife Service, Department of Range, Wildlife, and Fisheries Management, Texas Tech University,
Lubbock, Texas 79409, USA
3
Department of Mathematics and Statistics, Texas Tech University, Lubbock, Texas 79409, USA
Received 25 May 2006; accepted 10 September 2006
ABSTRACT. Shorebirds migrating through the Southern Great Plains (SGP), USA, use freshwater playas and
saline lakes as stopovers. The importance of playas is well documented, but the role of saline lakes is not clearly
understood. During 2002 and 2003, we conducted surveys to determine the extent to which the saline lakes
serve as stopovers. Twenty-eight species were recorded, and total seasonal abundance ranged from 6779 to 29,924
birds. Potential shorebird abundance for extant saline lakes was estimated at 37,000–71,000 shorebirds annually.
American Avocets (Recurvirostra americana), Western Sandpipers (Calidris mauri), Baird’s Sandpipers (C. bairdi),
Least Sandpipers (C. minutilla), Snowy Plovers (Charadrius alexandrinus), Killdeer (Charadrius vociferus), and
Wilson’s Phalaropes (Phalaropus tricolor) were the most abundant species. Community composition of shorebirds
differed between saline lakes and regional freshwater playas. Peak spring abundance was generally in April, whereas
summer/fall migration was more protracted and shorebird abundance peaked during 6–8 weeks in August and
September. Migration chronologies differed among morphologically similar species, and among representative species
from different guilds. Such patterns of temporal separation permit partitioning of resources by shorebirds migrating
through the SGP. The saline lakes of the SGP should be regarded as stopover sites of regional and international
value. To ensure that saline lakes function as stopovers and to help maintain those unique communities that inhabit
them, conservation of saline lakes should focus on preserving spring flows and conserving water.
SINOPSIS. Composición de la comunidad y cronologı́a migratoria de playeros que utilizan
los lagos salobres de las grandes planicies del sur de los EUA
Los playeros que migran a través de las grandes planicies del sur de los Estados Unidos, utilizan como lugares
de parada playas de agua fresca y lagos salobres. La importancia de las playas ha sido muy bien documentada, pero
no se entiende bien el rol que puedan tener los lagos salobres. Durante el 2002 y el 2003, realizamos trabajos para
determinar hasta que punto los lagos salobres servı́an como lugares importantes de parada. En estos, enontramos la
presencia de 28 especies y una abundancia que varı́a entre 6779 y 29,924 aves. El uso potencial de estos lagos salinos
es de 37,000 a 71,000 individuos. Las especies más abundantes en este tipo de habitat resultaron ser Recurvirostra
americana, Caladris mauri, C . bairdi, C . minutilla, Charadrius alexandrinus y Phalaropus tricolor. La composición
de playeros resultó ser diferente en las playas de agua fresca y en los lagos salobres. El pico en la abundancia durante
la primavera, se llevó a cabo generalmente en Abril, mientras que el pico de los migrantes de verano/otoño ocurrió
por un periodo de 6–8 semanas de agosto a septiembre. La cronologı́a migratoria tiene sus diferencias entre especies
de morfologı́a similar, al igual que en especies de otros grupos. Este patrón de separación temporera, permite la
repartición de recursos entre las aves que migran a través de las grandes planicies. Los lagos salobres en dicha área
deben ser considerados como lugares de paradas de gran importancia a nivel nacional e internacional. Para asegurar
que dichos lagos salobres mantengan su función como lugares de paradas, la conservación de los mismos debe enfocar
el preservar el flujo de agua a estos durante la primavera.
Key words: migration chronology, playas, saline lakes, shorebirds, Southern Great Plains
Many shorebirds migrate through interior
North America between Arctic nesting grounds
and wintering areas in Central and South
America (Morrison 1984, Skagen and Knopf
4
Corresponding author. Email: andreia@lincolnu.
edu
C 2006
1993, Davis and Smith 1998a). These migrants
need to replenish and accumulate energy reserves
(Morrison 1984, Senner and Howe 1984, Myers
et al. 1987) at stopover sites along the migration
route (Skagen and Knopf 1993). Millions of
shorebirds use the 25,000 playas of the Southern
Great Plains (SGP) (Davis and Smith 1998b) as
important “stepping stones” (Skagen and Knopf
C 2006 Association of Field Ornithologists
The Author(s). Journal compilation 372
Vol. 77, No. 4
Shorebird Use of Saline Lakes
1993) necessary to complete their migration.
In addition to freshwater playas (Smith 2003),
there are approximately 45 saline lakes (Reeves
and Reeves 1996) in the SGP. The breeding
biology of shorebirds on saline lakes (Conway et
al. 2005) has been documented, but the extent
to which migrant shorebirds use saline lakes as
stopovers is unknown.
Unlike playas that are freshwater-recharge
wetlands, the saline lakes of the SGP are large,
sparsely vegetated, saline (>4 ppt) discharge
wetlands (Brüne 1981, Andrei 2005). Historically, numerous springs fed by the Ogallala
aquifer discharged in the saline lakes (Brüne
1981), and these lakes and associated springs
once served as perennial aquatic habitats for
wildlife. By the 1950s, spring flows had been
severely reduced due to declining aquifer levels,
and several lakes completely dried (Brüne 1981).
Since then, water levels of the Ogallala aquifer
have continued to decline (Triplet 1998, Sophocleous 2000). The freshwater playas of the SGP
are filled by rainfall runoff and serve as recharge
points for the Ogallala aquifer (Osterkamp and
Wood 1987, Smith 2003). Playas are generally
smaller than saline lakes (Guthery and Bryant
1982, Reeves and Reeves 1996).
Shorebird communities using saline lakes during migration may differ from those using playas
(Davis and Smith 1998a) because of ecological
differences between these two types of habitats.
Data concerning composition, abundance, and
migration chronology of shorebirds using the
saline lakes will aid the United States Shorebird Conservation Plan (Brown et al. 2001)
by identifying potentially important stopovers
in the Playa Lakes region. Information about
shorebird migration chronologies may be important for developing conservation strategies for
saline lakes. Further, a comparison of migration
chronologies of shorebirds using saline lakes
may help explain how shorebirds use the unpredictable resources (Haukos and Smith 1992)
of the spatially dynamic wetlands (Skagen and
Knopf 1993) in the Great Plains. A temporal
separation of migrant shorebirds, noted for their
dietary flexibility (Skagen and Oman 1996),
may allow partitioning of foraging resources by
morphologically similar shorebirds (Davis and
Smith 1998a). Our objectives were to (1) document the relative abundance and community
composition of shorebirds using saline lakes of
the SGP during spring and summer/fall migra-
373
tions, (2) examine differences between shorebird communities using freshwater playas and
those using saline lakes, (3) examine migration
chronologies of shorebirds in saline lakes and
test for differences in migration chronologies
among species within guilds as well as among
species from different guilds, and (4) propose
conservation recommendations for shorebirds
using saline lakes of the SGP.
METHODS
Study area. Our study was conducted in
the SGP of Texas and New Mexico, USA.
(Fig. 1). Formed by wind erosion and dissolution of salts (Reeves and Reeves 1996) and
ranging in size from approximately 4 ha (Frost
Lake, 32◦ 49 34.77 N and 102◦ 00 42.77 W) to
over 6000 ha (Cedar Lake, 32◦ 49 06.64 N and
102◦ 16 21.89 W), the saline lakes are generally
larger than playas (x¯ = 6.3 ha) of the SGP (Smith
2003). Vegetation cover (≤1%; Andrei 2005)
in the shallow (0–100 cm) saline lakes consists of plants such as Saltgrass (Distichlis spp.),
Pickleweed (Salicornia spp.), Bulrush (Scirpus
spp.), and Saltcedar (Tamarix spp.). Originally
covered by short- to mid-grass prairies, the SGP
are among the most intensely cultivated regions
in the world (Bolen et al. 1989). Preceding
and during our study, precipitation recorded in
Lubbock, Texas, was below the yearly average
of 48 cm (32.9 cm in 2001, 47.6 cm in 2002,
and 20.9 cm in 2003; National Oceanic and
Atmospheric Administration 2004).
Shorebird surveys. Saline lakes were located and identified following Reeves and Reeves
(1996; Fig. 1). We asked for permission to access
lakes from landowners and surveyed shorebirds
on all lakes where permission was granted. Because obtaining permission was random, we
surveyed a random sample of saline lakes in the
SGP. Shorebird surveys were conducted weekly
during spring (10 March–15 June 2002 and
2 March–7 June 2003) and summer/fall (7 July–
9 November 2002 and 7 July–8 November
2003). In 2002, 21 lakes were surveyed during
spring and 25 during summer/fall. In 2003
27 lakes were surveyed during both spring and
summer/fall. During surveys we either counted
all birds from one location at the edge of the lake
or by walking along the edge of the lake when
all shorebirds were not visible from one location.
We used 10 × 50 binoculars and a 20–50 × 80
374
A. E. Andrei et al.
J. Field Ornithol.
Fall 2006
Fig. 1. Study area and locations of the saline lakes of the Southern Great Plains (after Reeves and Reeves
(1996)). There are two or more lakes at some locations, including Yellow House, Cunavea Basin, Twin Lakes,
Double Lakes, Four Lakes, and Muleshoe National Wildlife Refuge.
spotting scope. Large flocks were counted by
dividing them into groups of 5, 10, or 20 individuals and using landmarks to divide flocks
into groups that could be counted accurately.
We performed repeated counts on large flocks
(several hundred individuals) and averaged the
results (Colwell and Cooper 1993). Because
lakes were relatively open and unvegetated, we
Vol. 77, No. 4
Shorebird Use of Saline Lakes
assumed all shorebirds at each lake were visible
and counted. To minimize bias associated with
conducting surveys on the same lake at the same
time on consecutive weeks, we assigned weekly
survey times randomly for each lake to one of
three diurnal periods: early day (sunrise–11:00),
midday (11:00–15:00), and late day (15:00–
sunset; Davis and Smith 1998a).
Data analysis. We summed survey data
across lakes and within each season of each year
to determine abundance (number of shorebirds
observed per season) and species composition
(percent of total number of observed birds per
season for each species). We estimated annual
shorebird use days for all saline lakes throughout the SGP by: (1) assuming a turnover of
shorebirds of 7 d (Skagen and Knopf 1994b),
(2) estimating annual shorebird use days for the
surveyed lakes, and (3) extrapolating relative to
the total number of saline lakes in the SGP. For
each season (spring or summer/fall), we averaged
the total number of birds of the more common
species (>5 individuals) observed during a migration season for the 2 years of study (2002
and 2003). Similarly, we averaged the seasonal
abundances of each shorebird species observed in
playas of the SGP for the two study years for each
season and each species, as reported by Davis
and Smith (1998a) for 1993 and 1994. For each
season (spring and summer/fall), we used averaged seasonal abundances of the more common
species to compare community composition of
shorebirds of saline lakes and playas with 2
tests for independence (Zar 1996). Pearson’s 2
was the test statistic. We also examined possible
differences between average seasonal abundance
and species composition (percent of total number of birds per season) of shorebirds in saline
lakes and playas. We used the statistical analysis
system (SAS Institute 2000) for all analyses.
To test for differences in migration chronologies of shorebirds, we categorized species
into foraging guilds according to Skagen and
Oman (1996), and used 2 tests for independence (Sokal and Rohlf 1981) to compare
small prober/gleaners (Least, Semipalmated,
Baird’s, and Western sandpipers; scientific
names of all shorebirds mentioned in the
text are provided in the Appendix) and
representative species from different foraging guilds, including a small prober/gleaner
(Least Sandpiper), a medium gleaner/prober
375
(Lesser Yellowlegs), a gleaner/sweeper (Wilson’s
Phalarope), a gleaner/prober (American Avocet),
a large gleaner/prober (Long-billed Curlew),
and two medium gleaner/probers (Long-billed
Dowitcher and Stilt Sandpiper). We used the
numbers of birds of each species observed during each week of migration to compare migration chronologies for each season of each year
(spring and summer/fall of 2002 and 2003)
with 2 . Pearson’s 2 was the test statistic (Zar
1996).
RESULTS
In 2002 16 lakes were used by shorebirds
during the spring and 20 were used during the
summer and fall. In 2003 17 lakes were used
by shorebirds during the spring and 10 during
the summer and fall. We observed 28 species of
shorebirds during our study (spring: 26 species
in 2002 and 24 in 2003; summer/fall: 26 species
in 2002 and 28 in 2003; see Appendix).
The most frequently observed species during
spring migration were Snowy Plover, Killdeer,
American Avocet, Western Sandpiper, Baird’s
Sandpiper, and Wilson’s Phalarope (Table 1).
During summer/fall migration, the most common species were American Avocet, Western
Sandpiper, Baird’s Sandpiper, and Wilson’s
Phalarope (Table 1).
Shorebirds were observed using 23 of the
45 saline lakes of the SGP during 2002 and
2003, years with below average precipitation.
Assuming a turnover of shorebirds of 7 d (Skagen and Knopf 1994b), conservative annual
estimates of shorebird use days for surveyed
saline lakes are 36,703 for 2002 and 18,628
for 2003. An extrapolation to all saline lakes
of the region (×2), assuming similar habitat
conditions in unsurveyed lakes, suggests a range
of 37,256 to 73,406 shorebird use days annually. The length of stay at the saline lakes
likely varies among species and between seasons and years depending on available habitat
conditions. Skagen and Knopf (1994b) reported
average lengths of stay between 3.4 and 9.7 d for
Semipalmated and White-rumped sandpipers in
Kansas.
Shorebird communities using playas and
saline lakes differed during both spring ( 2 16 =
2769.3, P < 0.001) and summer/fall ( 2 16 =
19,797.4, P < 0.001) migration. In spring
J. Field Ornithol.
Fall 2006
A. E. Andrei et al.
376
Table 1. Relative abundance and species composition (% of total number of observed birds per season) of
migrant shorebirds using saline lakes of the Southern Great Plains, Texas and New Mexico, during spring (2
March–15 June) and summer/fall (7 July–9 November) of 2002 and 2003.
Spring
2002
a
Summer/Fall
2003
2002
2003
b
Species
N
%
N
%
N
%
N
Snowy Plover
878
12.95
504
6.73
693
2.32
914
Killdeer
761
11.23
411
5.49
531
1.77
581
Black-necked Stilt
195
2.88
48
0.64
100
0.33
71
American Avocet
1673
24.68
809
10.80
1101
3.68
1775
Spotted Sandpiper
36
0.53
13
0.17
28
0.09
19
Greater Yellowlegs
21
0.31
44
0.59
56
0.19
109
Lesser Yellowlegs
42
0.62
4
0.05
39
0.13
68
Long-billed Curlew
46
0.68
12
0.16
28
0.09
175
Semipalmated Sandpiper
301
4.44
155
2.07
280
0.94
443
Western Sandpiper
942
13.90
487
6.50
2593
8.67
1713
Least Sandpiper
574
8.47
565
7.54
1078
3.60
1057
White-rumped Sandpiper
119
1.76
30
0.40
40
0.13
67
Baird’s Sandpiper
377
5.56
1053
14.06
5788
19.34
1957
Pectoral Sandpiper
35
0.52
45
0.60
59
0.20
12
Stilt Sandpiper
24
0.35
96
1.28
242
0.81
32
Long-billed Dowitcher
44
0.65
45
0.60
380
1.27
32
Wilson’s Phalarope
652
9.62
3138
41.90
16,746
55.96
2058
Other speciesc
59
0.86
31
0.42
142
0.48
55
Total
6779
7490
29,924
11,138
a
See Appendix for scientific names and a list of all species observed at the saline lakes.
b
N = number of birds of each species observed per season.
c
See Appendix for a complete list of shorebirds observed in the saline lakes of the Southern Great
during spring and fall migration, 2002–2003.
%
8.21
5.22
0.64
15.94
0.17
0.98
0.61
1.57
3.98
15.38
9.49
0.60
17.57
0.11
0.29
0.29
18.48
0.51
Plains
Table 2. Mean abundance (x¯) and species composition (% of the seasonal mean) of the common (>5
individuals observed per season) shorebirds observed per migration season during spring surveys at playas
(1993 and 1994; Davis and Smith 1998a) and saline lakes (2002 and 2003) of the Southern Great Plains,
Texas and New Mexico.
Playas
Species
x¯
%
x¯
a
Snowy Plover
132
1.67
691
Killdeer
726.5
9.19
586
Black-necked Stilt
181.5
2.30
121.5
American Avocet
1893
23.95
1241
Spotted Sandpiper
92.5
1.17
24.5
Greater Yellowlegs
61.5
0.78
32.5
Lesser Yellowlegs
77.5
0.98
23
Long-billed Curlew
16
0.20
29
Semipalmated Sandpiper
84.5
1.07
228
Western Sandpiper
436
5.52
714.5
Least Sandpiper
227.5
2.88
569.5
White-rumped Sandpiper
5
0.06
74.5
Baird’s Sandpiper
182
2.30
715
Pectoral Sandpiper
103.5
1.31
40
Stilt Sandpiper
368.5
4.66
60
Long-billed Dowitcher
1401.5
17.73
44.5
Wilson’s Phalarope
1914.5
24.22
1895
Total
7903.5
7089.5
a
See Appendix for scientific names and a list of all species observed at saline lakes.
Saline lakes
%
9.75
8.27
1.71
17.50
0.35
0.46
0.32
0.41
3.22
10.08
8.03
1.05
10.09
0.56
0.85
0.63
26.73
Vol. 77, No. 4
Shorebird Use of Saline Lakes
377
Table 3. Mean abundance (x¯) and species composition (% of the seasonal mean) of the common (>5
individuals observed per season) shorebirds observed per migration season during summer/fall surveys at
playas (1993 and 1994; Davis and Smith 1998a) and saline lakes (2002 and 2003) of the Southern Great
Plains, Texas and New Mexico.
Playas
Saline lakes
x¯
%
x¯
Species
Snowy Plover
91
0.58
803.5
Killdeer
771.5
4.93
556
Black-necked Stilt
323.5
2.07
85.5
American Avocet
2560
16.35
1438
Spotted Sandpiper
46.5
0.30
23.5
Greater Yellowlegs
301
1.92
82.5
Lesser Yellowlegs
1352
8.63
53.5
Long-billed Curlew
2618
16.72
101.5
Semipalmated Sandpiper
111
0.71
361.5
Western Sandpiper
560.5
3.58
2153
Least Sandpiper
895
5.72
1067.5
White-rumped Sandpiper
5
0.03
53.5
Baird’s Sandpiper
464
2.96
3872.5
Pectoral Sandpiper
98.5
0.63
35.5
Stilt Sandpiper
1329
8.49
137
Long-billed Dowitcher
3493.5
22.31
206
Wilson’s Phalarope
640.5
4.09
9402
Total
15, 660.5
20, 432.5
a
See Appendix for scientific names and a list of all species observed at saline lakes.
a
Wilson’s Phalaropes and American Avocets were
dominant (>10%) both at playas and saline
lakes, Long-billed Dowitchers were dominant
only at playas, and Baird’s Sandpipers and Western Sandpipers were dominant only at saline
lakes. Least Sandpipers (8.03% of the seasonal
total at saline lakes and 2.88% at playas) and
Snowy Plovers (9.75% of the seasonal total at
saline lakes and 1.67% at playas) were also
more dominant in saline lakes (Table 2). During
summer/fall migrations (Table 3), Long-billed
Curlews, Long-billed Dowitchers, and American Avocets were dominant (>10%) at playas,
whereas Wilson’s Phalaropes, Western Sandpipers, and Baird’s Sandpipers were dominant
at saline lakes. Snowy Plovers were found more
frequently at saline lakes (3.93%) than playas
(0.58%), whereas, Lesser Yellowlegs (8.63%
vs. 0.26%) and Stilt Sandpipers (8.49% vs.
0.67%) were observed more frequently at playas
(Table 3).
Overall, migration (all shorebirds combined)
was longer in the summer/fall than the spring
(Fig. 2). Peak numbers were generally observed
during 4–6 weeks in the spring and 6–8 weeks
in the summer/fall.
%
3.93
2.72
0.42
7.04
0.12
0.40
0.26
0.50
1.77
10.54
5.22
0.26
18.95
0.17
0.67
1.01
46.01
Spring migration chronologies of small
prober/gleaners (Baird’s, Least, Semipalmated,
and Western sandpipers) differed (2002: 2 27 =
1896.4, P < 0.001; 2003: 2 36 = 607.2, P <
0.001) (Fig. 3). Least Sandpipers and Semipalmated Sandpipers were the earliest migrants,
followed by Baird’s Sandpipers in early April.
Western Sandpipers were late migrants, reaching
peak abundance during mid-April.
Spring migration chronologies among the
four representative species of shorebirds (small
prober/gleaner—Least Sandpiper, medium
gleaner/prober—Lesser Yellowlegs, gleaner/
sweeper—Wilson’s Phalarope, and gleaner/
prober—American Avocet) differed in 2002
( 2 33 = 1396.9, P < 0.001) and 2003 ( 2 36 =
1244.1, P < 0.001; Fig. 3). American Avocets
and Lesser Yellowlegs reached peak abundance
during early April, whereas Wilson’s Phalaropes
reached peak abundance during late April.
Migration chronologies of Long-billed
Curlews, Long-billed Dowitchers, and Stilt
Sandpipers differed in spring 2002 ( 2 14 =
114.6, P < 0.001) and 2003 ( 2 24 = 67.3,
P < 0.001). Long-billed Curlews were early
migrants and departed by mid-April, whereas
40
40
2002
2002
Percent
J. Field Ornithol.
Fall 2006
A. E. Andrei et al.
378
30
30
20
20
10
10
0
0
1
15
1
15
1
15
1
1
15
1
15
1
15
1
15
1
15
1
15
1
15
1
40
40
2003
2003
30
30
20
20
10
10
0
0
1
15
March
1
15
April
1
15
1
1
M ay
15
July
1
Aug
Sept
Oct
Date
Fig. 2. Migration chronologies (percent of total number of observed birds for each season) of shorebirds (all
species combined) using the saline lakes of the Southern Great Plains, spring and summer/fall 2002–2003.
Stilt Sandpipers migrated during the second half
of April and in May. Long-billed Dowitchers
had a protracted migration lasting from
mid-March to mid-May (Fig. 3).
Summer/fall
migration
chronologies
of Baird’s Sandpipers, Least Sandpipers,
Semipalmated Sandpipers, and Western
Sandpipers differed in 2002 ( 2 27 = 1896.4,
P < 0.001) and 2003 ( 2 36 = 607.2, P < 0.001)
(Fig. 4). Baird’s, Least, and Western sandpipers
exhibited similar migration chronologies
(July–September), whereas most semipalmated
Sandpipers migrated from mid-August to
mid-September.
Summer/fall chronologies differed among
American Avocets, Least Sandpipers, Lesser
Yellowlegs, and Wilson’s Phalaropes in 2002
( 2 51 = 3673.8, P < 0.001) and 2003 ( 2 48 =
2700.1, P < 0.001) (Fig. 4). In 2002 all four
species migrated between mid-July and midSeptember and exhibited some overlap. In 2003
most Lesser Yellowlegs arrived in mid-September
and departed by the end of September.
Migration chronologies of Long-billed
Curlews, Long-billed Dowitchers, and Stilt
Sandpipers differed during summer/fall in 2002
( 2 14 = 114.6, P < 0.001) and 2003 ( 2 24 =
67.3, P < 0.001; Fig. 4). Stilt Sandpipers were
early migrants, reaching peak abundance during
late July, followed by Long-billed Dowitchers
and Long-billed Curlews during August.
DISCUSSION
Several wetland complexes are important
stopover sites for shorebirds in interior North
America. These include Horsehead and Sibley
Lakes in North Dakota, Cheyenne Bottoms
in Kansas, Great Salt Plains National Wildlife
Refuge (NWR) in Oklahoma (Senner and Howe
1984), the prairie potholes (Deleon and Smith
1999), and playas of the SGP (Davis and Smith
1998a). At least 37,000 shorebirds use the saline
lakes in the SGP annually. Because these lakes
are scattered over a vast landscape, they should
Shorebird Use of Saline Lakes
Vol. 77, No. 4
American Avocet
Wilson's Phalarope
Lesser Yellowlegs
60
60
Percent
50
2002
40
30
30
20
20
10
10
0
15
1
15
1
15
Long billed Curlew
Percent
1
1
15
1
15
Long-billed Dowitcher
1
15
1
Stilt Sandpiper
60
2002
50
50
40
40
30
30
20
20
10
10
2003
0
0
1
15
1
15
1
Baird's Sandpiper
Percent
2003
0
1
60
Least Sandpiper
50
40
60
379
15
1
1
15
1
Semipalmated Sandpiper
15
1
15
1
Western Sandpiper
60
2003
2002
50
50
40
40
30
30
20
20
10
10
0
0
1
15
March
1
15
April
1
15
May
1
1
15
March
1
15
April
1
15
1
May
Date
Fig. 3. Migration chronologies (percent of total number of observed birds for each species) of 10 common
shorebird species using the saline lakes of the Southern Great Plains, spring (March–June) 2002–2003.
be considered as Western Hemisphere Shorebird
Reserve Network (WHSRN) landscape sites of
regional importance (Skagen 2005). Moreover,
communities of birds using saline lakes differ
from those using the 25,000 freshwater playas
that are used by millions of shorebirds when
they are wet (Davis and Smith 1998a). Thus, the
mosaic of isolated wetlands in the entire SGP
should be considered as a WHSRN landscape
site of hemispheric importance (Skagen 2005).
American Avocet
Wilson's Phalarope
Lesser Yellowlegs
60
Percent
50
50
40
40
30
30
20
20
10
10
15
1
15
1
15
1
Long billed Curlew
15
1
1
1
15
1
15
1
15
1
Stilt Sandpiper
60
2002
Percent
15
Long-billed Dowitcher
60
50
50
40
40
30
30
20
20
10
10
2003
0
0
1
15
1
15
1
Baird's Sandpiper
50
2003
0
1
60
Least Sandpiper
60
2002
0
Percent
J. Field Ornithol.
Fall 2006
A. E. Andrei et al.
380
15
1
15
1
1
15
1
15
Semipalmated Sandpiper
1
15
1
15
1
Western Sandpiper
60
2002
50
40
40
30
30
20
20
10
10
0
2003
0
1
15
July
1
15
Aug
1
15 1
Sept
15
Oct
1
1
15
July
1
15
Aug
1
15
Sept
1
15
1
Oct
Date
Fig. 4. Migration chronologies (percent of total number of observed birds for each species) of 10 common
shorebird species using the saline lakes of the Southern Great Plains, summer/fall (July–November) 2002–
2003.
Species composition and abundance of migrant shorebirds at saline lakes in our study
varied between seasons and years. Seasonal and
yearly variation in the composition of migrant
shorebirds have also been reported at other wet-
lands in the Great Plains (Skagen and Knopf
1994a, Davis and Smith 1998a). Variation in
community composition and abundance of migrant shorebirds is likely a function of regional
availability of habitats and food along migration
Vol. 77, No. 4
Shorebird Use of Saline Lakes
routes, nesting success and survival on the breeding grounds, and different migration routes during spring and fall (Morrison 1984, O’Reilly and
Wingfield 1995).
Comparison of our results with those of
Davis and Smith (1998a) suggests differences
among species in the use of playas and saline
lakes of the SGP, with several species, including Snowy Plover (a highly imperiled species,
USSCP 2004), Western Sandpiper, Wilson’s
Phalarope, and Baird’s, Least, and Semipalmated
sandpipers, observed more frequently at the
saline lakes than at playas. Sandpipers (Calidris
spp.), small-bodied shorebirds with many potential predators (Barnard 1980, Whitfield 1985),
may prefer saline lakes because their sparsely vegetated mudflats offer good visibility for predator
detection and avoidance (Metcalfe 1984). Differences among species of shorebirds using saline
lakes and playas may also be due to changes
in shorebird populations. Playas were surveyed
in 1993 and 1994 (Davis and Smith 1998a)
and the saline lakes were surveyed in 2002
and 2003 (our study). Some species, such as
Wilson’s Phalaropes, may have expanded their
range (Colwell and Jehl 1994), and populations
of highly imperiled species, such as the Longbilled Curlew (USSCP 2004), have declined.
Our results revealed differences in migration
chronologies among species within guilds and
among species in different guilds. Specifically,
small prober/gleaners (Least, Semipalmated,
Baird’s, and Western sandpipers), representative species from different foraging guilds
(Least Sandpipers, Lesser Yellowlegs, Wilson’s
Phalaropes, and American Avocets), and
large and medium gleaner/probers (Long-billed
Curlews, Long-billed Dowitchers, and Stilt
Sandpipers) exhibited temporal segregation at
the saline lakes during spring and summer/fall
migration. As a result fewer individuals use food
resources at the saline lakes at any given time and
reduce the likelihood that resources will become
limiting, particularly in the spring when invertebrate prey are less abundant (Davis and Smith
1998a, Andrei 2005). When food resources
are depleted (Schneider and Harrington 1981)
or potentially limiting (Székely and Bamberger
1992), shorebirds may not be able to replenish
energy reserves and experience reduced survival
and recruitment (Duffy et al. 1981, Schneider
and Harrington 1981).
381
Unlike playas of the SGP (Smith 2003),
most saline lakes are created and maintained
by springs fed by the Ogallala aquifer that is
heavily used for irrigation of crops and domestic
uses (Triplet 1998, Sophocleous 2000). Further, the Ogallala aquifer is primarily recharged
through playas of the SGP (Osterkamp and
Wood 1987, Wood and Osterkamp 1987, Wood
2000). Therefore, conservation of playas, important stopover habitats for migrant shorebirds
(Davis and Smith 1998a), may also help conserve
saline lakes and the springs discharging into
them. Preserving saline lakes of SGP as stopovers
for shorebirds would likely require conservation
of water on local and regional scales and purchase
of easements for irrigation rights. Maintaining
and restoring grasslands in areas surrounding
playas and the saline lakes would reduce use
of aquifer water for irrigation near saline lakes,
likely reduce sedimentation in the recharge areas
of playas, and restore and improve spring flows.
ACKNOWLEDGMENTS
We thank W. Johnson and S. McMurry for comments
on the manuscript. L. M. Smith was supported by the
Caesar Kleberg Foundation for Wildlife Conservation.
This is manuscript T-9-1113 of the College of Agricultural
Sciences and Natural Resources, Texas Tech University.
Funding and logistic support were provided by the United
States Fish and Wildlife Service, Texas Parks and Wildlife
Department, and Playa Lakes Joint Venture.
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Vol. 77, No. 4
Shorebird Use of Saline Lakes
383
Appendix. Shorebirds observed (“x”) in saline lakes of the Southern Great Plains of Texas and New Mexico
during spring and summer/fall migrations, 2002–2003.
Common name
Black-bellied Plover
American Golden-Plover
Snowy Plover
Semipalmated Plover
Killdeer
Black-necked Stilt
American Avocet
Spotted Sandpiper
Solitary Sandpiper
Greater Yellowlegs
Willet
Lesser Yellowlegs
Long-billed Curlew
Hudsonian Godwit
Marbled Godwit
Sanderling
Semipalmated Sandpiper
Western Sandpiper
Least Sandpiper
White-rumped Sandpiper
Baird’s Sandpiper
Pectoral Sandpiper
Dunlin
Stilt Sandpiper
Long-billed Dowitcher
Wilson’s Snipe
Wilson’s Phalarope
Red-necked Phalarope
Scientific name
Pluvialis squatarola
Pluvialis dominica
Charadrius alexandrinus
Charadrius semipalmatus
Charadrius vociferus
Himantopus mexicanus
Recurvirostra americana
Actitis macularius
Tringa solitaria
Tringa melanoleuca
Tringa semipalmata
Tringa flavipes
Numenius americanus
Limosa haemastica
Limosa fedoa
Calidris alba
Calidris pusilla
Calidris mauri
Calidris minutilla
Calidris fuscicollis
Calidris bairdii
Calidris melanotos
Calidris alpina
Calidris himantopus
Limnodromus scolopaceus
Gallinago delicata
Phalaropus tricolor
Phalaropus lobatus
Spring
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
Summer/Fall
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×