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there is no evidence of renesting, but curlews will
continue laying eggs in another nest if the first nest is
destroyed during laying (Allen 1980, Jenni et al. 1981,
Paton and Dalton 1994).
In Idaho, Oregon, British Columbia, Colorado,
and Utah, 4-egg clutches comprised 89.3 percent (range
= 80–96 percent, n = 103 nests; Redmond and Jenni
1986), 90 percent (n = 112, 9 percent contained 3 eggs;
Pampush and Anthony 1993), 61.3 percent (n = 31, 22.5
percent contained 3 eggs; Cannings 1999), 91 percent
(n = 11; King 1978), and 100 percent (n = 9; Paton and
Dalton 1994) of nests, respectively.
Hatching success for successful nests in Idaho
was 91.3 percent (n = 254 eggs, 3-year range =
88.4–94.1 percent; Redmond and Jenni 1986). Causes
of egg loss in otherwise successful nests (n = 69 over
3 years) included infertility or embryo death (n = 7
eggs); parental abandonment of late, asynchronously
hatching eggs (n = 5 eggs); and trampling by livestock
(n = 6 eggs) (Redmond and Jenni 1986). Mayfield
nest success ranged from 69.0 percent (n = 40 nests)
and 65.0 percent (n = 61) in Oregon (Pampush and
Anthony 1993), to 39.7 percent (n = 119) in Idaho
(Redmond and Jenni 1986), and 33.6 percent (n =
21) in Wyoming (Cochrane and Anderson 1987). Nest
success (apparent success) was reported as only 20
percent in Utah, (n = 10; Paton and Dalton 1994). A
mean of 0.25 chicks fledged per breeding adult per year
(range = 0.16–0.38, n = 3 years) in an Idaho study;
early-nesting adults consistently fledged more chicks
than late-nesting adults (0.30 vs. 0.19; Redmond and
Jenni 1986). Survival of radio-marked chicks from
hatching to fledging in Idaho was 39 percent (20 of 51
chicks, n = 3 years), but it was highly variable among
years—75 percent (9 of 12), 15 percent (2 of 13), and
35 percent (9 of 26) (Redmond and Jenni 1986). The
proportion of females that rear at least one brood to
independence is unknown. There is no information on
lifetime reproductive success for this species.
There has been only one study (Idaho) of an
extensively marked population of long-billed curlews
(Redmond and Jenni 1986), and our knowledge of
lifespan, survivorship, and immigration/emigration
between populations for this species is limited. Annual
survival (= annual return rate) of breeding adults (based
on resighting data) over 3 years in Idaho was 89 percent
± 0.10 SD, 64 percent ± 0.10 SD, and 84 percent ± 0.16
SD. There is little information on natal philopatry; most
young birds apparently emigrate from the local area
where they fledge, as no birds marked as chicks were
ever seen on breeding areas as yearlings (Redmond and
Jenni 1986). The average life span is reported as 8 to 10
years (Redmond and Jenni 1986). Maximum life span is
unknown, but the survival record for the bristle-thighed
curlew (Numenius tahitiensis) is 24 years (Bird Banding
Lab data). Because individuals are long-lived, with high
annual adult survival rates (Redmond and Jenni 1986),
fluctuations in annual productivity are probably less
important than factors influencing adult survival.
Ecological influences on survival and
reproduction
Based on observed interannual variation in
clutch size, food availability (either on breeding or
migration areas) may limit long-billed curlew survival
and distribution (Redmond and Jenni 1986). Climatic
instability and variation in rainfall create perturbations
in plant and invertebrate productivity, plant species
composition, and plant physiognomic structure
(Albertson and Weaver 1944). Annual precipitation
may influence vegetation characteristics on the breeding
grounds, which can influence distribution (Dugger and
Dugger 2002). Dry years reduce the productivity
of plants and invertebrates, which likely influences
the distribution and productivity of curlews. Winter
resources and the climatic factors that affect them may
determine much of the structure of avian communities
in both winter and summer (Pulliam and Enders 1971,
Fretwell 1972, Wiens 1974, Raitt and Pimm 1976).
Additionally, xeric conditions can magnify the effects of
grazing on plant productivity, and changing cultivation
practices can completely change the distribution of
winter food resources.
During the breeding season, severe and unstable
climate patterns are thought to erode the normally close
coupling of arthropod abundance with vegetation. Thus,
features other than prey abundance and territory-wide
vegetation characteristics may drive habitat selection in
curlews, including microclimate at the nest, predation
risk, and more efficient foraging in certain microhabitats
(Martin 1986).
Spacing,
defense and size of area,
and
population regulation
Long-billed curlews defend nesting territories
from pre-laying through hatching of eggs (Allen 1980,
Pampush 1980, Jenni et al. 1981). Territory size ranges
from 6 to 8 ha (southeastern Washington) to 14 ha
(Idaho), with a buffer of unoccupied habitat 300 to 500
m wide around the edge of each territory (Allen 1980,
Jenni et al. 1981). Nesting territory appears primarily
related to the nest site, rather than food resources; adults