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habitat for foraging, nesting, and brood
rearing
v
protect the area around nest sites since
curlews often reuse the same territories in
subsequent years
v
protect curlew breeding habitat from
detrimental
human activities
v
adjust timing and intensity of grazing
treatment according to environmental factors
(Bicak et al. 1982, Cochran and Anderson
1987, Bock et al. 1993).
v
limit insect control where long-billed curlews
occur since one of their primary foods is
grasshoppers; when pest management is
required, apply rapidly degrading chemicals
of low toxicity to non-target organisms at the
lowest application rates possible (McEwen et
al. 1972)
v
restore the inherent heterogeneity of native
grazing communities and encourage larger
grazing allotments
v
discourage the control of prairie dogs on
public
lands in southern, shortgrass prairies
v
avoid planting non-native grass species
such as wheatgrasses that may discourage
occupancy by curlews; where rehabilitation
or reclamation of prairie is necessary, seeding
should be done with native shortgrass and
mixed-grass (e.g., blue grama, buffalograss,
prairie junegrass, needlegrass)
v
avoid fragmentation of existing tracts of
mixed-grass and shortgrass habitat.
Inventory and monitoring of populations and
habitat
Broad-scale information on long-billed curlew
population status includes that of the BBS and CBC
programs. These have been discussed in the “Existing
Regulatory Mechanisms, Management Plans, and
Conservation Strategies” section. At a broad geographic
scale, BBS surveys on the breeding grounds provide
the information necessary to detect continental trends
in distribution and long-term changes in abundance.
BBS results may be used as a guide to local or
regional management decisions, with several caveats.
BBS results are often inconclusive due to difficulties
associated with the interpretation of index counts (Sauer
2000). Many species (especially less common species)
and habitats are inadequately sampled, and BBS data do
not reliably predict population trends at fine geographic
scales (Sauer 2000). Because habitat information is
not recorded, BBS data have only limited utility for
determining avian response to environmental change
or management actions. CBC surveys for curlews on
the wintering grounds may provide insight into long-
term, wintering-population trends in distribution and
abundance. Annual variation in observer effort and
aerial coverage within count circles, the participation
of inexperienced observers, and inadequate sampling of
habitats can compromise the interpretation and limit the
utility of CBC data.
At smaller, regional scales, point count techniques
(variable circular plots: e.g., Reynolds et al. 1980, Hutto
et al. 1986, Ralph et al. 1995) or line transect count
techniques (Burnham et al. 1980) are recommended to
detect population changes in response to management,
natural disturbance, or climate change. Both line
transect and point count distance sampling data may be
analyzed with the Windows-based computer package,
DISTANCE (Buckland et al. 2001, Thomas et al.
2002). The territory flush technique (Wiens 1969) and
spot mapping (International Bird Census Committee
1970) may also be employed at smaller scales. To
monitor breeding productivity, assess breeding habitat
conditions, and estimate densities at small scales, the
BBIRD protocol is often used (Martin et al. 1997). For
an overview and details on estimating bird numbers, see
Ralph and Scott (1980).
Vegetation and habitat should be characterized
in terms of both horizontal and vertical structure.
Techniques (e.g., Wiens 1969, Rotenberry and Wiens
1980) should include estimates of horizontal cover
(Daubenmire frames: Daubenmire 1959) and estimates
of vertical structure (e.g., Robel et al.1970) by
employing vertical rods (counting vegetation contacts)
and cover boards (estimating vertical coverage
class values within, e.g., 5-cm intervals). Horizontal
patchiness may be determined by using the coefficient
of variation of vertical structure across horizontal
distance (variation in vegetation contacts and coverage
class values, above; Rotenberry and Wiens 1980).
Long-term avian population monitoring coupled with
vegetation data will provide information on long-term
avian population trends, habitat relationships, and the
effects of land use.
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39
Information Needs
Fragmentation
The influences of landscape factors on the
reproductive success of long-billed curlews require
more investigation. The consequences of an increasingly
fragmented landscape on curlew abundance and
reproductive success are virtually unknown. Studies of
reproductive success, and prey and predator responses
in fragments of various sizes are needed. Minimum
patch size requirements in different habitat types and
physiographic regions are largely unknown.
Population surveys
Accurate population surveys are unavailable, and
development of techniques for conducting accurate,
rangewide breeding and wintering surveys should be a
research priority.
Wintering ecology
More research is needed on the wintering ecology
of curlews, particularly in non-coastal wintering areas,
including interior Mexico.
Fire and grazing
Special emphasis should be placed on the role,
effects, and utility of fire and various grazing regimes in
rehabilitating and maintaining curlew habitats.
Exotics
In non-native and altered landscapes, the effects
of different amounts and species of exotic grasses on
curlew reproductive success and pattern of use should
be examined.
Human disturbance
Research is needed to document the effect of
human disturbance and land-use practices throughout
the species’ range.
Taxonomy
The taxonomy of curlews and subspecies validity
remains unresolved; the results of such study may have
important conservation implications. Research on the
timing and extent of molts, and variation in plumages
may help to resolve subspecies status.
Habitat restoration
Seeding techniques and preferred grasses for
grassland reclamation, restoration, and enhancement
should be developed and tested.
Reproduction and foraging
Examination of curlew reproductive success,
fecundity, lifetime reproductive success, and how
these might change with grazing or habitat frag-
mentation is needed.
Relationship with prey/food populations
The nutritional and energy requirements of
curlews, the nutritional value of winter and summer
food items, and how the availability of food changes
with habitat alteration are unknown.
Relationship with predators
The responses of predators to habitat change
(e.g., grazing, fragmentation) and how this might affect
curlews are unknown.
Movement patterns
The extent of natal philopatry of curlews is
based on only one study. Adult dispersal and patterns
of emigration and immigration are virtually unknown,
limiting our knowledge of population demography.
Migration routes and key migration stopover sites and
threats to these areas need further study.
Prey response to habitat change
Studies of prey (e.g., earthworms, grasshoppers,
beetles) response to different grazing regimes,
drought and climate change, and prescribed burning
are needed.
Demography
Basic information on annual fecundity and
lifetime reproductive success of curlews is lacking,
especially in Region 2. Factors influencing adult
survival anytime during the year are poorly known.
Long-term studies of marked populations are
required for better estimates of recruitment, survival,
immigration, and emigration. Genetic studies of small,
isolated populations are needed to determine levels of
genetic diversity and gene flow.