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Lawrence D. Igl

Publications and source records attributed to Lawrence D. Igl.

At least 37 records · Page 2Linked to original sources
USGS2020

The effects of management practices on grassland birds—Savannah Sparrow ( Passerculus sandwichensis )

Keys to Savannah Sparrow ( Passerculus sandwichensis ) management are providing extensive grasslands of intermediate height and density with a well-developed litter layer, controlling succession, and protecting nesting habitat from disturbance during the breeding season. Savannah Sparrows have been reported to use habitats with 11–190 centimeters (cm) average vegetation height, 4–50 cm visual obstruction reading (VOR), 15–66 percent grass cover, 4–45 percent forb cover, less than (<) 29 percent shrub cover, <38 percent bare ground, 10–63 percent litter cover, and less than or equal to (≤) 21 cm litter depth.

Professional Paper↗
USGS2020

The effects of management practices on grassland birds—LeConte’s Sparrow ( Ammospiza leconteii )

Keys to LeConte’s Sparrow ( Ammospiza leconteii ) management include controlling succession and providing uplands and lowlands with tall, thick herbaceous vegetation and thick litter. LeConte’s Sparrows have been reported to use habitats with 30–90 centimeters (cm) average vegetation height, 19–41 cm visual obstruction reading, 35–43 percent grass cover, 16–27 percent forb cover, less than (<) 18 percent shrub cover, <4 percent bare ground, 39–45 percent litter cover, and 2–6 cm litter depth.

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USGS2020

The effects of management practices on grassland birds—Baird’s Sparrow ( Centronyx bairdii )

Keys to Baird’s Sparrow ( Centronyx bairdii ) management are providing native or tame grasslands with moderately deep litter, controlling excessive grazing, and curtailing shrub encroachment. Baird’s Sparrows have been reported to use habitats with less than or equal to (≤) 101 centimeters (cm) average vegetation height, 3–46 cm visual obstruction reading (VOR), 15–71 percent grass cover, 5–25 percent forb cover, ≤50 percent shrub cover, less than (<) 44 percent bare ground, 10–63 percent litter cover, and ≤21 cm litter depth.

Professional Paper↗
USGS2020

The effects of management practices on grassland birds—Chestnut-collared Longspur ( Calcarius ornatus )

Keys to Chestnut-collared Longspur ( Calcarius ornatus ) management are providing and maintaining native pastures with fairly short overall vegetation and sparse litter accumulation but with areas of taller and denser vegetation and accumulated litter for nesting, and tailoring grazing intensity to local conditions. Chestnut-collared Longspurs have been reported to use habitats with 10–77 centimeters (cm) average vegetation height, 1–50 cm visual obstruction reading, 15–67 percent grass cover, 5–16 percent forb cover, less than (<) 6 percent shrub cover, 1–44 percent bare ground, 6–63 percent litter cover, and <7 cm litter depth.

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USGS2020

The effects of management practices on grassland birds—Lark Bunting ( Calamospiza melanocorys )

Keys to Lark Bunting ( Calamospiza melanocorys ) management include providing short vegetation with protective nest cover and tailoring grazing systems to the type of grassland. Lark Buntings have been reported to use habitats with 6–72 centimeter (cm) average vegetation height, 2–11 cm visual obstruction reading, 13–71 percent grass cover, less than or equal to (≤) 48 percent forb cover, ≤17 percent shrub cover, 10–57 percent bare ground cover, 25 percent litter cover, and ≤2 cm litter depth.

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USGS2020

The effects of management practices on grassland birds—Merlin ( Falco columbarius )

The key to Merlin ( Falco columbarius ) management is maintaining an interspersion of groves of deciduous or coniferous trees for nesting and open grasslands for hunting. Merlins do not build their own nests but rather use former nests of other bird species, including those of corvids (crows, ravens, and magpies) and accipitrids (hawks). In recent decades, Merlins have established breeding populations in urban and residential areas in the northern Great Plains.

Professional Paper↗
USGS2020

The effects of management practices on grassland birds—Sprague’s Pipit ( Anthus spragueii )

Keys to Sprague’s Pipit ( Anthus spragueii ) management include providing suitable grassland habitat, especially native prairie, with intermediate vegetation height and low visual obstruction, and controlling succession therein. Sprague’s Pipits have been reported to use habitats with no more than 49 centimeters (cm) average vegetation height, 4–14 cm visual obstruction reading, 15–53 percent grass cover, less than (<) 21 percent forb cover, <18 percent shrub cover, <44 percent bare ground, 10–63 percent litter cover, and less than or equal to 11 cm litter depth.

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USGS2020

Evaluation of survey methods for colonial waterbirds at Chase Lake National Wildlife Refuge, North Dakota

Estimating the number of breeding pairs in a mixed-species waterbird colony is difficult because colonial waterbirds are vulnerable to human intrusion and their colonies are often in remote areas with limited access. We investigated methods to estimate the number of nests of waterbirds at a large, mixed-species colony at Chase Lake National Wildlife Refuge in south-central North Dakota. The primary goals of this study were to evaluate survey methods for shrub- and ground-nesting colonial waterbirds at Chase Lake National Wildlife Refuge and to develop protocols for estimating abundance of the different species. The specific objectives were (1) to assess visible-nest counts for ciconiiform species from the perimeter of nesting areas (hereafter, perimeter counts) and observational surveys from fixed points outside the colony to count flights of adult ciconiiforms in and out of the colony (hereafter, flightline surveys) as alternatives to within-colony counts of ciconiiform nests, and (2) to assess semiautomated, pixel-based image-analysis techniques to estimate abundance of American White Pelicans ( Pelecanus erythrorhynchos ) as an alternative to traditional manual counts from aerial photographs. For shrub-nesting ciconiiform species, observers counted 2,259 and 1,759 active ciconiiform nests in 2012 and 2013, respectively, during within-colony counts of ciconiiform nests. Results from within-colony counts of ciconiiform nests indicated a positive relation between the number of nests and the area of the shrub subcolony for the three most common ciconiiform species and all ciconiiform species combined. The perimeter nest counts of ciconiiform nests at Chase Lake represented only 18.8 percent of the total active ciconiiform nests counted in 11 subcolonies in 2012, which was well below the recommended target of 50 percent. Although we found a positive relationship between the number of nests counted during perimeter counts and the number of nests counted during within-colony counts for the three most common ciconiiform species and all ciconiiform species combined, perimeter counts at Chase Lake were hampered by disturbance to nesting birds. Thus, we discontinued the perimeter counts before they were completed. We did not develop predictive models from these perimeter counts in 2012 because these models could be misleading due to inconsistent application of the survey methods, which likely would have provided inaccurate perimeter counts. The extent of this issue is unknown. Flightline surveys at Chase Lake documented patterns of ciconiiform activity that were unknown for this region. For the common ciconiiform species, the number of flights to and from the South Island at Chase Lake were greatest in the morning (7:00−12:00 central daylight time [CDT]) and least in the afternoon (12:00−17:00), and least early in the breeding season (May 29–June 20, 2013) and greatest later in the breeding season (June 24–August 1, 2013). Flightline surveys are an index but lacked comparability with within-colony nest counts because the two methods provide measures of different things (that is, adult activity away from the colony as compared to the number of nests within the colony). The overall proportions of flights generally reflected the proportions of the within-colony nest counts for the four most common species: Black-crowned Night-Heron ( Nycticorax nycticorax ), Cattle Egret ( Bubulcus ibis ), Great Egret ( Ardea alba ), and Snowy Egret ( Egretta thula ). Flightline surveys at Chase Lake indicated apparent variation related to the time of day and season, as well as a variation in detection of inbound and outbound adult ciconiiforms. For ciconiiforms at Chase Lake, the most appropriate combination of survey approaches will depend on the need for annual estimates of nest abundance of ciconiiform species, balanced with the financial, personnel, and logistical constraints associated with the survey methods. For ground-nesting American White Pelicans, the results from this study indicated that digital-image processing using remote-sensing software provides an accurate estimate of the number of American White Pelican nests. Estimates of the number of pelican nests from digital-image processing, using two commercially available remote-sensing software packages, produced nest estimates that were comparable to those of traditional manual counts from aerial photographs.

North Dakota↗
USGS2020

The effects of management practices on grassland birds—Horned Lark ( Eremophila alpestris )

The key to Horned Lark ( Eremophila alpestris ) management is maintaining areas with short, sparse vegetation by burning, mowing, or grazing. Horned Larks have been reported to use habitats with less than or equal to (≤) 70 centimeters (cm) average vegetation height, 3–26 cm visual obstruction reading, 15–67 percent grass cover, 3–70 percent forb cover, ≤21 percent shrub cover, 1–44 percent bare ground, ≤63 percent litter cover, and ≤9 cm litter depth.

Professional Paper↗
USGS2019

The effects of management practices on grassland birds—Thick-billed Longspur (Rhynchophanes mccownii)

The key to Thick-billed Longspur ( Rhynchophanes mccownii ) management is providing short, sparsely vegetated native grasslands of adequate size. Mixed-grass prairies can be made suitable for breeding Thick-billed Longspurs by implementing moderate-to-heavy or season-long grazing. Thick-billed Longspurs have been reported to use habitats with 5–42 centimeters (cm) average vegetation height, 3–7 cm visual obstruction reading, 15–67 percent grass cover, less than (<) 8 percent forb cover, <7 percent shrub cover, 2–60 percent bare ground, 10–63 percent litter cover, and <5 cm litter depth.

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USGS2019

The effects of management practices on grassland birds—Northern Harrier ( Circus hudsonius )

The key to Northern Harrier ( Circus hudsonius ) management is providing tall, dense vegetation in extensive mesic or xeric grasslands or in wetlands. Northern Harriers have been reported to use habitats with 15–106 centimeter (cm) average vegetation height, 28–75 cm visual obstruction reading, 24–53 percent grass cover, 18–25 percent forb cover, less than or equal to 2 percent shrub cover, 3–5 percent bare ground, 23–30 percent litter cover, and 2–6 cm litter depth.

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USGS2019

The effects of management practices on grassland birds—Eastern Meadowlark ( Sturnella magna )

The key to Eastern Meadowlark ( Sturnella magna ) management is providing large areas of contiguous grassland of moderate height with significant grass cover and moderate forb density. Eastern Meadowlarks have been reported to use habitats with 10–187 centimeters (cm) average vegetation height, 6–88 cm visual obstruction reading, 53–86 percent grass cover, 4–50 percent forb cover, less than or equal to (≤) 4 percent shrub cover, less than 38 percent bare ground, 6–23 percent litter cover, and ≤13 cm litter depth.

Professional Paper↗
USGS2019

The effects of management practices on grassland birds—Mountain Plover ( Charadrius montanus )

The key to Mountain Plover ( Charadrius montanus ) management is maintaining sparsely vegetated grasslands. Grasslands can be made suitable for breeding Mountain Plovers by preserving large prairie dog ( Cynomys species) towns, conducting prescribed burns, or implementing heavy grazing in some situations. Mountain Plovers have been reported to use habitats with 2–38 centimeters average vegetation height, 14–87 percent grass cover, 2–14 percent forb cover, 4–55 percent shrub cover, 9–72 percent bare ground, 2 percent litter cover, and 4–6 cm litter depth.

Professional Paper↗
USGS2019

The effects of management practices on grassland birds—Upland Sandpiper ( Bartramia longicauda )

The key to Upland Sandpiper ( Bartramia longicauda ) management is providing grasslands of various heights with few shrubs. In general, Upland Sandpipers forage within short vegetation and nest and rear broods within taller vegetation. Upland Sandpipers have been reported to use habitats with less than (<) 93 centimeters (cm) vegetation height, 5–75 cm visual obstruction reading, greater than or equal to 33 percent grass cover, less than or equal to (≤) 50 percent forb cover, ≤13 percent shrub cover, 3–12 percent bare ground, 11–30 percent litter cover, and <13 cm litter depth.

Professional Paper↗
USGS2019

The effects of management practices on grassland birds—Long-billed Curlew ( Numenius americanus )

Keys to Long-billed Curlew ( Numenius americanus ) management include providing large, open, level to gently rolling grasslands with short vegetation, and tailoring grazing regimes to local conditions. Long-billed Curlews have been reported to use habitats with 3–75 centimeters (cm) average vegetation height, less than or equal to 27 cm visual obstruction reading, 20–71 percent grass cover, 4–50 percent forb cover, 2–12 percent shrub cover, 7–40 percent bare ground, and less than 3 cm litter depth.

Professional Paper↗
USGS2019

The effects of management practices on grassland birds—Marbled Godwit ( Limosa fedoa )

Keys to Marbled Godwit ( Limosa fedoa ) management include providing large expanses of short, sparsely to moderately vegetated landscapes that include native grasslands and wetland complexes. Optimal wetland complexes should contain a diversity of wetland classes and sizes, such as ephemeral, temporary, seasonal, semipermanent, permanent, and alkali wetlands, as well as intermittent streams. Marbled Godwits use wetlands of various salinities. The species has been reported to use habitats with less than or equal to 70 centimeters (cm) average vegetation height, 4–23 cm visual obstruction reading, and 1–9 cm litter depth.

Professional Paper↗