22
23
react to loud noises by crouching down on tarsi, pulling
in necks, and becoming silent (Forsythe 1973).
Both adults brood young chicks, regularly during
the first few days after hatch, particularly at night and
on cool mornings. Adults may shade the chicks during
warm weather; brooding appears to stop after chicks
reach about two weeks of age (Allen 1980, Jenni et
al. 1981). Chicks feed themselves after hatch (Jenni et
al. 1981), and adult care of young involves vigilance
and predator protection. Both parents tend the brood
initially, but the female abandons the brood after 2 to
3 weeks; the percentage of lone males attending broods
increases as the season progresses. The male usually
stays with the brood until fledging, but lone females are
occasionally observed caring for chicks.
Broods are defended from conspecifics. Terrestrial
predators are distracted with an injury-feigning display
by one or both adults (Allen 1980), and aerial predators
are mobbed, primarily by the male. Groups of adults
will mob raptors flying over territory clusters. The male
appears to take a more active role in brood defense,
while the female directs the movement of the brood
(Dugger and Dugger 2002). Adults continue to defend
prefledged young after hatch (Allen 1980, Jenni et al.
1981).Curlews may also defend non-breeding territories
(Colwell 2000, Colwell and Mathis 2001).
After hatch, broods remain =300 m from nest
for approximately 1 to 5 days (Allen 1980, Jenni et al.
1981). Long movements rarely occur before chicks are
10 days old; these trips often entail travel over 1 km per
day for 1 to 3 days. After 10 days, the pattern is long
moves followed by periods of remaining in a small
area for several days or weeks. Broods are estimated
to use 250 to 1,000 ha of habitat (Allen 1980, Jenni et
al. 1981).
Site and mate fidelity
Among returning breeders, there is some
indication that individuals re-pair with the same mate
in subsequent years (Allen 1980, Redmond and Jenni
1982). Males show higher site fidelity than females,
who may not return if exposed to excessive disturbance
or nest loss (Redmond and Jenni 1982). When birds do
return, they may return to the same nesting territory
(Redmond and Jenni 1982). There is no information on
fidelity to non-breeding areas or wintering sites. There
is little information on natal philopatry, but no birds
marked as chicks were ever seen on breeding areas
as yearlings (Redmond and Jenni 1986). The social
pair bond persists throughout the breeding season; the
female typically abandons the male and brood 2 to 3
weeks after hatching, leaving brood care to her mate.
Demography
Genetic issues
Phylogenetic analyses of morphological characters
suggest that the genus Numenius is monophyletic and
a sister taxon to Bartramia (e.g., upland sandpiper;
B. longicauda). Long-billed curlews are not closely
related to godwits, as previously suggested (Lowe 1931,
Strauch 1978, Mickevich and Parenti 1980, Chu 1995).
The long-billed curlew may constitute a superspecies
with Eurasian curlew (Mayr and Short 1970); it is
also very similar to and possibly closely related to
Far Eastern curlews. Differentiation of Numenius
is postulated to have occurred because of isolation
during the Pleistocene glaciation (Hubbard 1973). The
species is monotypic following Hellmayr and Conover
(1948), Bull (1985), and Patton et al. (2003), but some
authorities recognize two subspecies (Bishop 1910,
American Ornithologists’ Union 1957, Blake 1977).
Birds of northern and western populations (e.g., western
Canada, Washington, Oregon; N. americanus parvus)
are smaller with shorter bills, whereas those of central
U.S. breeding populations (e.g., Wyoming, Utah,
Nebraska, Colorado; N. a. americanus) are larger with
longer bills; average differences in size broadly overlap.
Long-billed curlews are socially monogamous, and
polygyny has not been reported; there is no evidence of
extra-pair copulations (Dugger and Dugger 2002).
Generally, the continued fragmentation of
mixed-grass and shortgrass habitats may have genetic
consequences. Fragmentation isolates populations,
increases the likelihood of local extinctions, decreases
the probability of colonization, and genetically isolates
populations. This leads to increased probabilities of
inbreeding and genetic drift, and a lowering of genetic
diversity. Fragmentation can potentially turn continuous
populations into “metapopulations of semi-independent
demes” that gradually disappear (Risser 1996). The
effects of fragmentation may be more severe where site
fidelity between breeding seasons is high, but there is
little information on long-billed curlew site fidelity.
Recruitment, survival, immigration, age at
reproduction
Female long-billed curlews breed at 2 to 3 years
of age; males breed at 3 to 4 years (Redmond and
Jenni 1986). Curlews presumably breed every year
thereafter. Females lay only one clutch per season;