Geology topics

Lawrence D. Igl

Publications and source records attributed to Lawrence D. Igl.

At least 19 recordsLinked to original sources

USGS2025

Developing research tools for demographic study of Rhynchophanes mccownii (thick-billed longspurs)

Like numerous other North American grassland bird species, Rhynchophanes mccownii (thick-billed longspur) has experienced severe population declines in the last 50 years. Little is known about population-limiting factors, and knowledge gaps limit conservation efforts on the species; however, before research studies aimed at improving conservation and management actions can be developed, other research must resolve notable knowledge gaps that exist in field techniques for efficient and effective large-scale demographic studies. We examined several techniques for the capture, marking (metal, color bands, and transmitters), and reencountering (resights and telemetry) of thick-billed longspurs in croplands and prairies in Valley County, Montana, during the 2022 and 2023 breeding seasons. Our goal was to evaluate the feasibility of obtaining within- and between-season resights of individual thick-billed longspurs using optical equipment and cameras, transmitter receivers, and the Motus automatic receiving station network. This report includes observations and insights that may aid researchers embarking on future demographic studies of thick-billed longspurs, as well as other grassland birds that provide similar research challenges.

Open-File Report↗

USGS2025

The effects of management practices on grassland birds—Field Sparrow ( Spizella pusilla )

Keys to Field Sparrow ( Spizella pusilla ) management include providing shrub-dominated edge habitat adjacent to grasslands or grasslands with a shrub component (both of which must include dense grass and moderately high litter cover) and avoiding disturbances that eliminate woody vegetation. Field Sparrows have been reported to use habitats with 16–134 centimeters (cm) vegetation height, 20–145 cm visual obstruction reading, 17–90 percent grass cover, 2–45 percent forb cover, less than 63 percent shrub cover, 3–7 percent bare ground, 14–30 percent litter cover, and 1–7 cm litter depth.

Professional Paper↗

USGS2024

Seasonal and breeding phenologies of 38 grassland bird species in the midcontinent of North America

Grasslands in the midcontinent of North America are highly imperiled, and grassland birds have suffered the largest bird declines of any terrestrial biome in North America in the last 50 years. Consequently, the conservation and management of grasslands, as well as their associated avian communities, are major priorities for the State, Provincial, and Federal agencies; non-governmental organizations; and private entities that influence the millions of hectares of grasslands in the midcontinent. Resource managers often deploy disturbances to grasslands (for example, grazing, haying, and burning) to maintain or enhance their quality or structure, but the timing of these disturbances has the potential to disrupt the nesting activities of grassland birds. In this report, we compiled two types of phenology information for 38 species of nonwaterfowl, grassland-nesting birds across four author-defined regions in the midcontinent of North America: (1) species- and region-specific arrival and departure dates from the eBird database, which indicate when a species may be assumed to be present in a region; and (2) reported dates of nesting activity for each species (start and end dates of nesting as well as total duration) from published bird distribution and occurrence books and breeding bird atlases, which indicate when nesting by a species may be assumed. This previously available but widely dispersed information, compiled for the first time, will aid resource managers and inform their decisions about the timing of disturbances while minimizing grassland management effects on nesting birds.

Open-File Report↗

USGS2023

The effects of management practices on grassland birds—Loggerhead Shrike (Lanius ludovicianus)

The key to Loggerhead Shrike ( Lanius ludovicianus ) management is providing open grasslands with scattered trees and shrubs for foraging, nesting, and perching. Loggerhead Shrikes have been reported to use habitats with 20–266 centimeters (cm) vegetation height, greater than or equal to (≥) 10 percent grass cover, 3–48 percent forb cover, 2–25 percent shrub cover, 3–40 percent bare ground, and 11–67 percent litter cover.

Professional Paper↗

USGS2023

The effects of management practices on grassland birds—Bobolink ( Dolichonyx oryzivorus )

Keys to Bobolink ( Dolichonyx oryzivorus ) management are providing large areas of suitable habitat (for example, native or tame grasslands of moderate vegetative height and density, low shrub density, and moderate litter and forb cover), and protecting nesting habitat from disturbance during the breeding season. Bobolinks have been reported to use habitats with 10–166 centimeters (cm) average vegetation height, 6–75 cm visual obstruction reading, 17–65 percent grass cover, 3–50 percent forb cover, less than or equal to (≤) 22 percent shrub cover, ≤38 percent bare ground, 5–39 percent litter cover, and ≤9 cm litter depth.

Professional Paper↗

USGS2023

The effects of management practices on grassland birds—Dickcissel ( Spiza americana )

Keys to Dickcissel ( Spiza americana ) management include providing dense, moderate-to-tall vegetation, particularly with a well-developed forb component, and moderately deep litter. Dickcissels have been reported to use grassland habitats with 4–166 centimeters (cm) average vegetation height, 6–85 cm visual obstruction reading, 11–68 percent grass cover, 1–86 percent forb cover, less than or equal to (≤) 10 percent shrub cover, less than (<) 27 percent bare ground cover, <30 percent litter cover, and ≤ 6 cm litter depth.

Professional Paper↗

USGS2023

The effects of management practices on grassland birds—Golden Eagle (Aquila chrysaetos)

Keys to Golden Eagle ( Aquila chrysaetos ) management in western North America’s grasslands, particularly those of the Great Plains region, include maintaining open, mostly undeveloped landscapes that sustain at least modest population levels of suitable prey (most typically rabbits [Leporidae] and prairie dogs or ground squirrels [Sciuridae]); safeguarding nesting territories (that is, breeding areas), especially nest structures within territories, from human disturbances; mitigating major sources of anthropogenic mortality, particularly electrocution on powerlines, shooting, collisions with structures and vehicles, and poisoning by lead and rodenticides; and averting climate change.

Professional Paper↗

USGS2023

The effects of management practices on grassland birds—Clay-colored Sparrow ( Spizella pallida )

Keys to Clay-colored Sparrow ( Spizella pallida ) management include providing grasslands with a shrub or forb component or shrub-dominated edge habitat, which includes dense grass and moderately high litter cover, and avoiding disturbances that completely eliminate woody vegetation. Clay-colored Sparrows have been reported to use habitats with 20–186 centimeters (cm) average vegetation height, 3–50 cm visual obstruction reading, 15–74 percent grass cover, 5–23 percent forb cover, less than 30 percent shrub cover, 1–20 percent bare ground, 10–63 percent litter cover, and less than or equal to 5 cm litter depth.

Professional Paper↗

USGS2022

Potential effects of energy development on environmental resources of the Williston Basin in Montana, North Dakota, and South Dakota—Species of conservation concern

The ecosystems of the Williston Basin provide direct and indirect benefits to society. These benefits include carbon sequestration, flood control, nutrient rich soils for agricultural productivity, and habitat for wildlife. This chapter’s main focus is on the effects of energy development on species that occupy the ecosystems in the Williston Basin. We compiled a list of documented species of conservation concern that are of most interest to Federal regulators and resource managers. Species of concern were either listed as endangered or threatened under the Endangered Species Act or listed by States as species of concern in Natural Heritage Program checklists or State Wildlife Action Plans. All told, we determined that 357 species of concern likely occupy the Williston Basin. These species represented seven different taxonomic groups: plants (native and nonnative), terrestrial invertebrates, birds, mammals, reptiles and amphibians, and fish and mussels. We reviewed the existing scientific information pertaining to potential effects of energy development on these taxonomic groups. Currently, little is known about the abundance and distribution of many of these species. But some information exists that may be useful in predicting the potential effects of energy development on certain taxonomic groups. Most of this information has been developed through scientific research focused on effects to mammal and bird populations. Effects to other taxonomic groups seems to be understudied. In general, it seems that disturbances and modifications associated with development have the potential to negatively affect a wide range of species; however, many studies produce uncertain results because they are not designed to compare populations before and after energy development takes place. Most of these studies also do not monitor resources over multiple years and thus cannot detect population trends. Likewise, there are few examples of landscape-scale assessments of the cumulative effects of energy development that could be used for species or habitat management purposes. We suggest that more research needs to be completed to measure potential effects to a broad range of species in multiple taxonomic groups. This may require also developing some understanding about the basic ecology of many of the species covered in this report. In concert with this more basic research, we also suggest that more comprehensive assessments of potential negative cumulative effects across the Williston Basin should be developed in an effort to guide more strategic management of biological resources.

Montana, North Dakota, South Dakota↗

USGS2022

The effects of management practices on grassland birds—Burrowing Owl ( Athene cunicularia hypugaea )

Keys to Burrowing Owl ( Athene cunicularia hypugaea ) management include providing areas of short, sparse vegetation and maintaining populations of prey species and of burrowing mammals to ensure availability of burrows as nest sites. In particular, the conservation of black-tailed prairie dog ( Cynomys ludovicianus ) and Richardson’s ground squirrel ( Urocitellus richardsonii ) colonies is vital to the preservation of Burrowing Owls on the Great Plains. Burrowing Owls have been reported to use habitats with less than 31 centimeters (cm) average vegetation height, 5–12 cm visual obstruction reading, 12–36 percent grass cover, 29–45 percent forb cover, 1–11 percent shrub cover, 11–58 percent bare ground, and 6–27 percent litter cover.

Professional Paper↗

USGS2022

The effects of management practices on grassland birds—Greater Prairie-Chicken ( Tympanuchus cupido pinnatus )

The keys to Greater Prairie-Chicken ( Tympanuchus cupido pinnatus ) management are maintaining expansive grasslands; preventing populations of Greater Prairie-Chickens from becoming small and isolated; managing grasslands to maintain proper grassland height, density, and vigor; and reducing woody plant invasion and excessive litter buildup. Within these grasslands, areas should contain short herbaceous cover for lek sites; tall residual grasses for nesting; and disturbed habitats for broods with adequate vegetation regrowth that provides insects for food and cover from predators and weather. This account does not address population or harvest management but rather focuses on habitat management. Greater Prairie-Chickens have been reported to use habitats with 5–113 centimeter (cm) average vegetation height, 5–40 cm visual obstruction reading, 18–95 percent grass cover, 1–35 percent forb cover, <45 percent litter cover, <5 percent shrub cover, 3–25 percent bare ground, and <12 cm litter depth.

Professional Paper↗

USGS2021

The effects of management practices on grassland birds—Short-eared Owl (Asio flammeus)

The key to Short-eared Owl ( Asio flammeus ) management is providing large grasslands and wetlands, particularly those that can support high densities of voles ( Microtus species). Short-eared Owls have been reported to use habitats with 30–90 centimeters (cm) average vegetation height, 7–47 cm visual obstruction reading, 31–85 percent grass cover, 8–26 percent forb cover, less than 18 percent shrub cover, 43 percent litter cover, and 1–2 cm litter depth.

Professional Paper↗

USGS2021

The effects of management practices on grassland birds—Grasshopper Sparrow ( Ammodramus savannarum )

The key to Grasshopper Sparrow ( Ammodramus savannarum ) management is providing large areas of contiguous grassland of intermediate height with moderately deep litter and low shrub density. Grasshopper Sparrows have been reported to use habitats with 8–166 centimeters (cm) average vegetation height, 4–80 cm visual obstruction reading, 12–95 percent grass cover, 4–40 percent forb cover, less than 35 percent shrub cover, less than or equal to (≤) 38 percent bare ground, 5–61 percent litter cover, and ≤9 cm litter depth.

Professional Paper↗

USGS2021

The effects of management practices on grassland birds—Lark Sparrow (Chondestes grammacus)

Keys to Lark Sparrow ( Chondestes grammacus ) management include providing open grasslands with sparse-to-moderate herbaceous and litter cover and a woody component and allowing occasional burning or moderate grazing. Lark Sparrows have been reported to use habitats with 10–63 centimeters (cm) average vegetation height, 10–54 percent grass cover, 9–25 percent forb cover, 4–18 percent shrub cover, 16–38 percent bare ground, 12–45 percent litter cover, and less than or equal to 1 cm litter depth.

Professional Paper↗

USGS2020

The effects of management practices on grassland birds—Brewer’s Sparrow ( Spizella breweri breweri )

Keys to Brewer’s Sparrow ( Spizella breweri breweri ) management include maintaining extensive, unfragmented patches of suitable breeding habitat; reducing conifer cover and height; preventing the invasion of conifers and nonnative plants, especially cheatgrass (downy brome [ Bromus tectorum ]); minimizing disturbance to soil; and restricting the use of pesticides and herbicides during the breeding season (April–July). Brewer’s Sparrows have been reported to use breeding habitats with 12–170 centimeter (cm) vegetation height, 2–34 cm visual obstruction reading, 1–74 percent grass cover, less than (<) 19 percent forb cover, 1–65 percent shrub cover, 1–75 percent bare ground, 2–61 percent litter cover, and <1 cm litter depth. During post-fledging dispersal in July, Brewer’s Sparrow adults and young may shift habitat use to nearby aspen ( Populus species [spp.]), riparian shrub, or deciduous mountain shrub habitats, so these habitats also may be important for management.

Professional Paper↗

USGS2020

The effects of management practices on grassland birds—Nelson’s Sparrow ( Ammospiza nelsoni nelsoni )

The key to Nelson’s Sparrow ( Ammospiza nelsoni nelsoni ) management is providing dense grasses or emergent vegetation near damp areas or freshwater wetlands. Nelson’s Sparrows have been reported to use habitats with 20–122 centimeters (cm) average vegetation height, 41 cm visual obstruction reading, 40–58 percent grass cover, 24 percent forb cover, 5 percent shrub cover, 13 percent bare ground, and 2–7 cm litter depth.

Professional Paper↗

USGS2020

The effects of management practices on grassland birds—Lesser Prairie-Chicken ( Tympanuchus pallidicinctus )

The key to Lesser Prairie-Chicken ( Tympanuchus pallidicinctus ) management is maintaining expansive sand shinnery oak ( Quercus havardii ) or sand sagebrush ( Artemisia filifolia ) grasslands. Within these grasslands, areas should contain short herbaceous cover for lek sites (that is, an area where male prairie-chickens gather to engage in courtship displays to attract mates); shrubs or tall residual grasses for nesting; and areas with about 25 percent canopy cover of shrubs, forbs, or grasses 25–30 centimeters (cm) tall for brood rearing. Historically, the Lesser Prairie-Chicken was considered a gamebird that was hunted throughout its range. In response to low population levels and considerations related to listing the species as State or Federally threatened, recreational hunting seasons currently are closed throughout the species’ range. This account does not address harvest or its effects on populations but instead focuses on the effects of habitat management. Lesser Prairie-Chickens have been reported to use habitats with less than or equal to (≤) 600 cm average vegetation height (including shrubs), ≤70 cm visual obstruction reading, 4–78 percent grass cover, ≤30 percent forb cover, ≤66 percent shrub cover, 3–61 percent bare ground, 2–58 percent litter cover, and ≤3 cm litter depth.

Professional Paper↗

USGS2020

The effects of management practices on grassland birds—Sedge Wren ( Cistothorus stellaris )

Keys to Sedge Wren ( Cistothorus stellaris ) management include providing tall, dense grasslands with moderate forb coverage and minimizing disturbances during the breeding season. Sedge Wrens have been reported to use habitats with 30–166 centimeters (cm) average vegetation height, 8–80 cm visual obstruction reading, 15–75 percent grass cover, 3–78 percent forb cover, less than or equal to (≤) 15 percent shrub cover, less than (<) 35 percent bare ground, 10–30 percent litter cover, and ≤6 cm litter depth.

Professional Paper↗