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35
grasslands over non-native pastureland that is seeded
with exotics. Older plantings of crested wheatgrass
(Agropyron cristatum) and infestation of knapweeds
(Centaurea sp.) can severely degrade nesting habitat
by creating dense, tall stands of vegetation (Allen 1980,
Jenni et al. 1981, Pampush and Anthony 1993).
Recreation
Recreation is increasing in Region 2 (USDA
Forest Service 2002), and the negative effects of
recreation on bird species composition and nest
placement in both national forests and grasslands have
recently been documented (e.g., Miller et al. 1998).
Curlews are particularly sensitive to human disturbance
during the nesting period. Nest desertion, altered nest
placement, and disruption of feeding activities are
likely, depending on the intensity and duration of
recreation. Disturbance during brood rearing can be
especially detrimental (Jenni et al. 1981). Excessive
vehicle traffic (particularly off-road vehicles), dumping,
and recreational use of breeding habitats can result in
nest abandonment and disruption of critical parental
behaviors, including brooding or shading. In Idaho,
one nest and three chicks were lost to off-road vehicle
disturbance; a vehicle had run over one chick (Jenni et
al. 1981).
Energy development
Oil and gas exploration can negatively impact
wildlife through loss or fragmentation of habitat (i.e.,
well pads, roads, pipelines, storage tanks, power
lines, compressor and pumping stations), disturbance
(i.e., drilling, vehicle traffic), or environmental
contamination. New construction for oil and gas
exploration, wind-power development, and water well
drilling has intensified in recent years. In the Powder
River Basin of western Wyoming, for example,
15,811 oil and gas wells have been approved, and an
additional 65,635 are being considered to potentially
develop oil and gas reservoirs (Connelly et al. 2004).
Habitat loss to such activities has obvious negative
impacts on curlew populations. Secondary impacts
have been reported for other species. Ingelfinger
(2001), for example, found that roads associated with
natural gas development in sagebrush steppe reduced
the guild of sagebrush obligates by 50 percent within
100 m of roads. Lyon and Anderson (2003) reported
lower rates of greater sage-grouse (Centrocercus
urophasianus) nest initiation in areas disturbed by
the vehicle traffic associated with gas wells. Although
there have been no specific studies of the disturbance,
environmental contamination, or fragmentation effects
of oil and gas activities on curlews, these are likely
negative (Knopf 1996).
Application of chemicals
DDE residues in seven eggs from Umatilla
National Wildlife Refuge, Oregon, collected in 1978
averaged 4.26 µg per g (95 percent CI = 0.41–7.39)
fresh wet weight. DDE concentrations of 14.0 µg per g
wet weight were found in Alberta (n = 1; Peakall 1976).
Adults and young may be indirectly affected because
spraying significantly reduces arthropod abundance,
particularly grasshoppers (McEwen et al. 1972), a major
food in the curlew’s diet. Contaminant profiles suggest
that curlews pick up some chemicals on wintering
areas. In Oregon, three adult curlews were collected by
hand after people observed the birds exhibiting erratic
behavior (1981–1983). These birds were analyzed for
toxins, and the death of two of the birds was attributed
to contaminants (i.e., dieldrin, heptachlor epoxide, and
oxychlordane) (Blus et al. 1985).
Conservation Status of Long-billed
Curlews in Region 2
Historically, the breeding range of the long-billed
curlew has contracted, and a long-term population
decline is evident (Sauer et al. 2005). This decline
parallels mixed-grass and shortgrass prairie losses
to agriculture (mixed-grass: 72 to over 99 percent in
North Dakota, Nebraska, Alberta, Saskatchewan, and
Manitoba [Samson and Knopf 1994]; shortgrass: 30
percent in Colorado, 78 percent in Kansas, 65.4 percent
in Nebraska, and 12.1 percent in Wyoming [Knopf and
Rupert 1999]).
BBS data from 1966 to 2004 indicate that survey-
wide (U.S. and southern Canada), long-billed curlews
are declining at an annual rate of 1.6 percent per year (P
= 0.08; Figure 4). Declines are statistically significant
(P ≤ 0.05; where n >25 BBS routes) in USFWS Region
6, which includes USFS Region 2 states plus Utah,
Montana, and North Dakota, (2.7 percent per year;
Figure 5), in the Central BBS Region (3.2 percent
per year; Figure 6), and in Colorado (10.3 percent per
year). Marginally significant declines (0.05< P ≤ 0.10)
occurred in the Great Plains Roughlands Physiographic
Stratum (2.8 percent per year; P = 0.09) and South
Dakota (2.8 percent per year; P = 0.07). The BBS trend
estimates map (Figure 7) suggests that the declines are
occurring for the most part in USFS Region 2 states,
plus much of Montana, Utah, and North Dakota. Only
in the Great Basin do curlew populations appear to be
stable (Dugger and Dugger 2002). Because of historic