30
An examination of 18 adult long-billed
curlews collected during June in Alberta found 5,717
individuals of nine species of intestinal helminth-
endoparasites (Goater and Bush 1988), all but one
of which were picked up on the breeding grounds;
one, with a marine life cycle, was apparently picked
up before arrival on the breeding grounds. Cestodes
(Dictymetra numenii, D. nymphae, D. radiaspinosa, D.
paranumenii, Ophryocotyle insignis, and Anomotaenia
sp.), acanthocephalans (Mediorhynchus robustus), and
trematodes (Brachylaema fuscata) were also present,
mostly in the middle 50 percent of the intestine.
The host-specialists D. numenii and D. nymphae
always populated the anterior portion of the small
intestine. The intermediate host for D. radiaspinosa
and D. paranumenii is the two-striped grasshopper
(Melanoplus bivattatus), and grasshoppers are common
in the diet of long-billed curlews.
Additional records for endoparasites of long-billed
curlews include Dictymetra numenii (Nebraska and
New Mexico) and D. paranumenii and Mediorhynchus
apapillosus (New Mexico; Clark 1952, Butler and
Pfaffenberger 1981); the cestode, Choanotaenia
numenii (Nebraska; Owen 1946); and the trematodes,
Himasthla mcintoshi and
Zygocotyle lunata (Stunkard
1916). Curlews have also harbored echoinostomes
(H.
rhigedana,
Pelmatostomum
americanum,
Parorchis acanthus, Paratrema numenii, Maritrema
arenaria, Probolocorphye glandulosa, H. rhigedana,
and Pararchos acanthus), non-intestinal flukes
(Lyperosomm oswaldoi, L. sinuosum, and Cyclocoelum
obscurum; Dronen and Badley 1979), and third-stage
encapsulated nematode larvae (Spiruroidea; Bartlett et
al. 1987). Parasites of curlews have been found in the
intestine, lower intestine, bursa of Fabricius, bile duct,
liver, pancreas, and air sacs.
Competitors and habitat use
Winter range overlap with godwits and willets
may heighten competition with curlews. Other
species that may use habitat in a similar way and
respond similarly to threats, management, and
conservation activities include the western meadowlark
(Sturnella neglecta), savannah sparrow (Passerculus
sandwichensis), Baird’s sparrow (Ammodramus
bairdii), mountain plover, horned lark (Eremophila
alpestris), lark bunting (Calamospiza melanocorys),
McCown’s longspur (Calcarius mccownii), and
Sprague’s pipit (Anthus spragueii).
Envirogram of ecological relationships
The envirogram emphasizes the effects of
weather (especially rainfall), humans, and topography
on long-billed curlew resource availability, fecundity,
survival, phenology, and predation and competition
(Figure 12a, Figure 12b, and Figure 12c). Climate
affects vegetation growth and physiognamy, which
in turn are influenced by human impacts of grazing
and prairie dog control, which in turn affect curlew
food resources and cover. Through oil and gas
development, grazing, pesticides, and fire, humans
can severely alter the vegetation structure and
composition, both directly and by fragmenting
habitats; this can affect curlew fecundity, survival,
and distribution, both on the summering and
wintering grounds. Topography, via climate, mediates
vegetation structure, which influences microhabitat
at the nest, food resources, and the abundance and
distribution of predators and competitors.
C
ONSERVATION
Threats
Land-use practices
Most of the declines in long-billed curlew
populations, both past and present, have been
attributed to land-use practices that destroy native
prairie (Dugger and Dugger 2002). The loss of native
prairie is mostly due to rising agricultural and urban
development, especially the conversion of mixed-grass
and shortgrass prairies to cultivated fields (Stewart
1975). Mixed-grass prairie declines range from 72 to
over 99 percent in North Dakota, Nebraska, Alberta,
Saskatchewan, and Manitoba (Samson and Knopf
1994). The extent of the loss of shortgrass prairie to
agriculture (especially to winter wheat on marginally
arable lands) is also significant; in Saskatchewan, 83
percent of the original native prairie has been lost, and
in Wyoming, over 20 percent has been lost (Samson
and Knopf 1994). Nearly 32 percent of the shortgrass
prairie region in the southwestern Great Plains has
been converted to cropland (30.7 percent in Colorado,
78 percent in Kansas, 65.4 percent in Nebraska, and
12.1 percent in Wyoming; Knopf and Rupert 1999).
More recent rangeland losses to agriculture are smaller
by comparison, but not insignificant. In Colorado, for
example, 3.8 percent of the shortgrass and mixed-
grass prairie east of the Rocky Mountains was lost to
agriculture and urban expansion from 1982 to 1997
(Seidl et al. 2001).