McCown's Longspur Research Articles

Diversity in selection patterns of five grassland songbirds in dry-mixed grasslands of Alberta

Declining grassland bird populations across North America continue to be a concern. Understanding local relationships between grassland bird abundance and vegetative and landscape characteristics will enable more prescriptive recommendations to be made to land managers. We used point count survey data collected by the MULTISAR (Multiple Species At Risk) program along with field measurements of habitat and landscape characteristics on 15 ranches in the Dry Mixed-grass Subregion in southern Alberta to improve our understandings of habitat relationships for five grassland bird species: Baird’s Sparrow (<em>Centronyx bairdii</em>), Sprague’s Pipit (<em>Anthus spragueii</em>), Thick-billed Longspur (<em>Rhynchophanes mccownii</em>), Chestnut-collared Longspur (<em>Calcarius ornatus</em>), and Grasshopper Sparrow (<em>Ammodramus savannarum</em>). We used generalized linear mixed models to examine the relationship between the predicted abundance of a species and covariates that represented vegetative structure (e.g., litter), management (e.g., range health), and anthropogenic features (e.g., energy development) of habitat site selection. Model results demonstrate four vegetation structure covariates were of most importance for predicting abundance, including litter, vegetation height, bare soil, and shrub cover. Quadratic relationships were found with litter amounts for the predicted abundance of Baird’s Sparrow, Chestnut-collared Longspur, and Grasshopper Sparrow. Contrastingly, higher amounts of litter reduced the predicted abundance of Thick-billed Longspur. The relationship of vegetation height was quadratic for Sprague’s Pipit and was positive for Baird’s Sparrow, but negative for Thick-billed Longspur. As bare soil percentage increased, the predicted abundance of Baird’s Sparrow and Chestnut-collared Longspur decreased, with Sprague’s Pipit showing a quadratic association. Negative relationships were found with increased amounts of shrub cover for Chestnut-collared Longspur, Sprague’s Pipit, and Thick-billed Longspur. Our results help to further understand individual grassland bird species’ habitat requirements, enabling us to provide land management recommendations for maintaining, improving, or creating the heterogenic environments needed for a variety of grassland birds in the Dry Mixed-grass Subregion.

Thick-billed Longspur (Rhynchophanes mccownii) reproduction shows minimal short-term response to conservation-based program

El escribano Rhynchophanes mccownii es una especie con estatus de conservación preocupante que depende de praderas bajas y estepas del occidente de Norteamérica. Estos hábitats han sido grandemente alterados de ser ecosistemas dominantes y diversos a pequeños parches de pasturas homogéneas mezcladas con tierras agrícolas. Sin embargo, existe poca información de cómo el uso del suelo afecta la demografía de estos escribanos. Este estudio evalúa los beneficios de un programa que incentiva la conservación de tierras privadas (CBP) en la reproducción del escribano. Comparamos el éxito de anidación y densidad según datos colectados en pasturas que se inscribieron en un CBP con aquellas de pasturas que no formaban parte del programa. Las pasturas en el CBP experimentaron un régimen específico de pastoreo de descanso-rotación, mientras que no hubo requisitos para las pasturas que no formaban parte del programa. Usamos un modelo de superpoblación de estado-espacio que cuantifica la disponibilidad de nidos mientras estima su detección. Detectamos y monitoreamos 74 nidos de escribano a lo largo de 2 temporadas reproductivas, incluyendo 28 nidos en pasturas en el CBP. Nuestros resultados sugieren estimaciones similares de éxito de anidación y densidad de nidos entre nidos de pasturas en el CBP y los nidos en pasturas que no participaban en el programa de conservación. Nuestras estimaciones de éxito de anidación y densidad de nidos avanzan nuestro entendimiento de la influencia de un programa de conservación de pájaros con incentivos y da una visión en 2 métricas de reproducción del escribano. Palabras clave: aves canoras, densidad de nidos, escribano, éxito de anidación, ganado, pastoreo prescrito, reproducción.

Fine‐scale habitat associations of Oklahoma's longspurs

AbstractOverwintering is a key demographic stage for migratory birds but remains poorly understood, especially among multiple declining grassland bird species. The non‐breeding ranges all 4 species of longspur (i.e., chestnut‐collared [Calcarius ornatus], Smith's [C. pictus], Lapland [C. lapponicus], thick‐billed [Rhynchophanes mccownii]) overlap in Oklahoma and the Texas Panhandle, USA, making this region ideal to study their wintering ecology. We evaluated the relationship between wintering longspur occurrence and fine‐scale habitat characteristics using a combination of standardized bird surveys and vegetation plot sampling. Our study encompassed large, representative tracts of 3 prairie ecosystems (i.e., shortgrass, mixed‐grass, and tallgrass prairies) that intersect within the Southern Great Plains, during winters of 2018–2019 and 2019–2020. Using randomization tests and classification trees, we characterized longspur habitats and compared these associations across the 3 prairie ecosystems. Fine‐scale winter habitats (horizontal structure, vertical structure, and species compositions) varied among all 4 longspur species, varied at very fine scales, and differed between grassland types. Our findings can be applied to the management of grasslands such as decreasing vegetation height in mixed‐grass prairies for chestnut‐collared longspurs or removing woody vegetation in shortgrass prairies for thick‐billed longspurs to help develop full‐life cycle conservation for longspurs, which have experienced population declines.

Habitat Targets for Imperiled Grassland Birds in Northern Mixed-Grass Prairie

Grassland bird populations are declining faster than any other avian guild in North America, and promotion of favorable habitat conditions in rangeland breeding cores is important for their maintenance. There is much information on associations between breeding grassland songbirds and vegetation attributes. However, previous results have been difficult to translate into management practices due to mismatch between the scale and metrics used in biological sampling and those used in management. Here, we evaluate the response of imperiled grassland bird species to vegetation conditions using metrics and scales accessible to managers. We focus on four species that are experiencing particularly severe population declines: Baird's sparrow (Centronyx bairdii), chestnut-collared longspur (Calcarius ornatus), McCown's longspur (Rynchophanes mccownii), and Sprague's pipit (Anthus spragueii). In 2017 and 2018, we evaluated the abundances of these species within their core distributions in northern Montana. We used temporally replicated point-counts and hierarchical models to estimate abundance and associations with plot-level (9-ha) vegetation conditions while accounting for spatially and temporally variable detectability. Exotic grass encroachment and shrub cover had negative or neutral effects on all species. Birds responded strongly to biomass at this scale, with chestnut-collared longspurs and Sprague's pipit preferring a range of 1 100 kg ha−1 to 1 400 kg ha−1, and McCown's longspurs selecting for the lowest available. Residual grass and litter cover were important for Baird's sparrows. Variable results among species emphasize the need for heterogeneity in vegetation structure and composition at scales larger than the plot. Our results provide guidance for managers interested in improving habitat for these species.

Adaptive rangeland management benefits grassland birds utilizing opposing vegetation structure in the shortgrass steppe.

Rangelands are temporally and spatially complex socioecological systems on which the predominant land use is livestock production. In North America, rangelands also contain approximately 80% of remaining habitat for grassland birds, a guild of species that has experienced precipitous declines since the 1970s. While livestock grazing management may benefit certain grassland bird species by generating the vegetation structure and density they prefer, these outcomes are poorly understood for avian species breeding in the shortgrass steppe. We evaluated how two grazing management systems, continuous, season-long grazing and adaptive, rest-rotational grazing, affected grassland bird abundance from 2013 to 2017 in Colorado's shortgrass steppe. We examined grazing impacts in conjunction with ecological sites, which constitute unique soil and plant communities. When grazing management was evaluated in conjunction with spatial variation in ecological sites, we found three of our five focal bird species responded to grazing management. McCown's Longspur abundance decreased in pastures rested from grazing the previous year. The effect of grazing on Horned Lark and Grasshopper Sparrow depended on ecological site: Horned Lark density was highest in pastures that were intensively grazed and Grasshopper Sparrow density was highest in pastures that were rested the previous year in the least productive ecological site. In addition, densities of all species varied across ecological sites. Our results suggest consideration of soil and vegetation characteristics can inform how adaptive management is applied on a landscape to benefit the full suite of breeding grassland birds, including species that have seemingly contrasting habitat needs. For example, a manager could target adaptive drought mitigation practices, such as resting pastures for 1 yr to generate grassbanks, in less productive soils to benefit grassland birds that prefer taller/denser vegetation structure, or could apply intensive, short-duration grazing on less productive soils to benefit species preferring shorter/sparser vegetation. A single year of intensive, short-duration grazing (i.e., one component of our rotational treatment) across the landscape, however, might not create sufficient habitat for species that prefer short/sparse vegetation in our system (e.g.,McCown's Longspur). Ultimately, our study indicates how cattle production on rangelands can congruently support grassland bird populations in the shortgrass steppe.

Semi‐arid grassland bird responses to patch‐burn grazing and drought

ABSTRACTAs grassland birds of central North America experience steep population declines with changes in land use, management of remaining tracts becomes increasingly important for population viability. The integrated use of fire and grazing may enhance vegetation heterogeneity and diversity in breeding birds, but the subsequent effects on reproduction are unknown. We examined the influence of patch‐burn grazing management in shortgrass steppe in eastern Colorado on habitat use and reproductive success of 3 grassland bird species, horned lark (Eremophila alpestris), lark bunting (Calamospiza melanocorys), and McCown's longspur (Rhynchophanes mccownii), at several spatial scales during 2011 and 2012. Although no simple direct relationship to patch‐burn grazing treatment existed, habitat selection depended on precipitation‐ and management‐induced vegetation conditions and spatial scale. All species selected taller‐than‐expected vegetation at the nest site, whereas at the territory scale, horned larks and McCown's longspurs selected areas with low vegetation height and sparse cover of tall plants (taller than the dominant shortgrasses). Buntings nested primarily in unburned grassland under average rainfall. Larks and longspurs shifted activity from patch burns during average precipitation (2011) to unburned pastures during drought (2012). Daily survival rate (DSR) of nests varied with time in season, species, weather, and vegetation structure. Daily survival rate of McCown's longspur nests did not vary with foliar cover of relatively tall vegetation at the nest under average precipitation but declined with increasing cover during drought. At the 200‐m scale, increasing cover of shortgrasses, rather than taller plant species, improved DSR of larks and longspurs. These birds experience tradeoffs in the selection of habitat at different spatial scales: tall structure at nests may reduce visual detection by predators and provide protection from sun, wind, and rain, yet taller structure surrounding territories may host nest predators. Patch‐burn grazing management in combination with other strategies that retain taller‐structured vegetation may help sustain a diversity of breeding habitats for shortgrass birds under varying weather conditions. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Songbird response to rest-rotation and season-long cattle grazing in a grassland sagebrush ecosystem

Grazing on natural rangelands, which are areas dominated by native vegetation that are used for livestock grazing, can achieve desired vegetation outcomes, preserve native habitat, and economically benefit multiple stakeholders. It is a powerful tool that can be manipulated to reduce wildlife declines and benefit ecosystems. However, the benefits of conservation grazing systems on many wildlife communities remain relatively unexplored. We compared songbird communities between two grazing systems in eastern Montana: rest-rotation, which is a conservation grazing system, and season-long. We measured differences in abundance of eight songbird species over a two year period using dependent double-observer transect surveys and a multispecies dependent double-observer abundance model. The species were chosen to be representative of the sagebrush grassland community: a sagebrush obligate, Brewer's sparrow (Spizella breweri); a faculatative grassland species, brown-headed cowbird (Molothrus ater); grassland obligate species, chestnut-collared longspur (Calcarius ornatus), horned lark (Eremophila alpestris), lark bunting (Calamospiza melanocorys), McCown's longspur (Rhynchophanes mccownii), and western meadowlark (Sturnella neglecta); and a generalist, vesper sparrow (Pooecetes gramineus). Our results show that these species exhibit mixed responses to these two grazing systems. The sagebrush obligate (Brewer's sparrow), generalist (vesper sparrow), and two grassland associated species (horned lark and chestnut-collared longspur) were equally abundant on both grazing systems, suggesting grazing system had no effect on their abundance. However, the remainder of the grassland associated species showed a response to grazing: three (brown-headed cowbird, lark bunting, and western meadowlark) were more abundant in season-long than rest-rotation, whereas one (McCown's longspur) was more abundant in rest-rotation. These results suggest that differences in grazing management affect a subset of grassland obligate species and that only one species, McCown's longspur, preferred conservation grazing. Our findings provide useful information for assessing the suitability of grazing as a conservation tool for songbirds.

Comparison of removal-based methods for estimating abundance of five species of prairie songbirds

Estimating species abundance is important for land managers, especially for monitoring conservation efforts. The two main survey methods for estimating avian abundance are point counts and transects. Previous comparisons of these two methods have either been limited to a single species or have not included detection probability. During the 2012 breeding season, we compared and assessed the efficiency (precision for amount of effort) of point count time of detection (PCTD) and dependent double-observer transect (TRMO) methods based on detection probabilities and abundance estimates of five species of songbirds that use a range of habitats in a prairie system in Montana dominated by sagebrush and grassland vegetation. Our focal species included Vesper Sparrows (Pooecetes gramineus), a generalist species found in both shrub and grassland habitat, shrub-obligate Brewer's Sparrows (Spizella breweri), and McCown's Longspurs (Rhynchophanes mccownii), Horned Larks (Eremophila alpestris), and Western Meadowlarks (Sturnella neglecta), three species of grassland obligates that prefer different grass heights. Detection probabilities were significantly higher for TRMO surveys, with less variation for all five species and differences most pronounced for Brewer's Sparrows and Horned Larks. PCTD surveys required less field effort (~8–20 fewer people minutes per plot) than TRMO surveys because the TRMO surveys required two people. However, time spent on TRMO surveys provided between 0.38 and 87 times more precision per people minute than PCTD surveys. Our results suggest that TRMO surveys provide a more efficient (measured as time spent per unit of standard error) field-based technique in sagebrush prairie systems for the species we investigated, resulting in more precise detection and abundance estimates.

Reproductive success of Horned Lark and McCown's Longspur in relation to wind energy infrastructure

ABSTRACT Wind energy is a rapidly expanding industry with potential indirect effects to wildlife populations that are largely unexplored. In 2011 and 2012, we monitored 211 nests of 2 grassland songbirds, Horned Lark (Eremophila alpestris) and McCown's Longspur (Rhynchophanes mccownii), at 3 wind farms and 2 undeveloped reference sites in Wyoming, USA. We evaluated several indices of reproductive investment and success: clutch size, size-adjusted nestling mass, daily nest survival rate, and number of fledglings. We compared reproductive success between wind farms and undeveloped sites and modeled reproductive success within wind farms as a function of wind energy infrastructure and habitat. Size-adjusted nestling mass of Horned Lark was weakly negatively related to turbine density. In 2011, nest survival of Horned Lark decreased 55% as turbine density increased from 10 to 39 within 2 km of the nest. In 2012, however, nest survival of Horned Lark was best predicted by the combination of vegetation height, ...

Patch-burn grazing management, vegetation heterogeneity, and avian responses in a semi-arid grassland

Anthropogenic changes to disturbance regimes in grasslands, and associated homogenization of vegetation structure, have been implicated as factors contributing to declines in populations of grassland birds in North America. We examined the influence of patch-burn grazing management, which employs spatiotemporal interactions between fire and livestock grazing guided by historical disturbance patterns, on vegetation structure and bird abundance in shortgrass steppe in northeastern Colorado, USA. All study pastures were grazed by cattle at moderate stocking rates from May to October each year. In the patch-burn treatment, we burned 25% of each pasture in autumn (Oct or Nov) each year during 2007–2010; control pastures were not burned. Patch-burn grazing management increased vegetation heterogeneity by generating short (<4 cm), sparse vegetation on recent burns. Although cattle selectively grazed recent burns, this did not alter vegetation structure in unburned portions of patch-burned pastures relative to controls. Of the 6 grassland bird species we examined, mountain plovers (Charadrius montanus) occurred exclusively on recent burns, whereas grasshopper sparrows (Ammodramus savannarum) occurred exclusively in grassland not burned for ≥3 years. Two species (lark bunting [Calamospiza melanocorys] and western meadowlark [Sturnella neglecta]) were 2–3 times less abundant on recent burns compared to controls, whereas densities of horned larks (Eremophila alpestris) and McCown's longspur (Rhynchophanes mccownii) were unaffected by burning. Lark bunting, western meadowlark, and grasshopper sparrow densities varied substantially among years. In the years when they were abundant, all 3 species increased in density across the time-since-burning gradient. Consistent with this pattern, patch-burn grazing management reduced the abundance of all 3 species at the whole-pasture scale. We found no evidence that unburned patches within the patch-burned pastures differed from unburned pastures in terms of the abundance of any bird species. Patch-burn grazing management was an effective strategy to create breeding habitat for mountain plovers. However, our findings suggest that in the shortgrass steppe, additional strategies that generate taller, more dense vegetation than occurs under moderate cattle grazing need to be considered in combination with patch-burn grazing management to sustain breeding habitat for the full suite of native grassland birds. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Grassland songbirds exhibit variable responses to the proximity and density of natural gas wells

Cultivation of native prairie was likely the primary cause of historical declines of grassland bird populations in North America, but the increase in natural gas development may be exacerbating those declines through habitat loss and degradation. We quantified the abundance of grassland songbirds and vegetation structure across a gradient of natural gas well densities to determine the extent to which density and proximity of gas wells influence songbird abundance. In 2008 and 2009, we conducted 1,258 point counts on 105 native grassland parcels (1.6 km2/parcel) at varying distances from natural gas wells and with varying gas well densities (0–25 per 1.6 km2). We found that vegetation structure influenced bird abundance more strongly than natural gas well proximity or density for all but 1 species and that the response of grassland songbirds to natural gas well density and proximity varied among species and regions. Sprague's pipit (Anthus spragueii) and Baird's sparrow (Ammodramus bairdii) abundance was not influenced by natural gas well proximity or density. Grasshopper sparrow (Ammodramus savannarum), McCown's longspur (Rhynchophanes mccownii), and chestnut-collared longspur (Calcarius ornatus) abundance was lower near gas wells, but both longspur species were also more abundant in areas with greater densities of gas wells. Horned lark (Eremophilus alpestris) abundance increased with well density in our northern study site. Savannah sparrow (Passerculus sandwichensis) abundance was higher near gas wells, but only in areas where well density was ≤9 wells/1.6 km2. We suggest that land managers and industry implement remediation activities that encourage vegetative re-growth, thus reducing the potential interactive relationship between natural gas development and changes in vegetation structure. © 2014 The Wildlife Society.

Off-road sampling reveals a different grassland bird community than roadside sampling: implications for survey design and estimates to guide conservation

Grassland bird species continue to decline steeply across North America. Road-based surveys such as the North American Breeding Bird Survey (BBS) are often used to estimate trends and population sizes and to build species distribution models for grassland birds, although roadside survey counts may introduce bias in estimates because of differences in habitats along roadsides and in off-road surveys. We tested for differences in land cover composition and in the avian community on 21 roadside-based survey routes and in an equal number of adjacent off-road walking routes in the grasslands of southern Alberta, Canada. Off-road routes (n = 225 point counts) had more native grassland and short shrubs and less fallow land and road area than the roadside routes (n = 225 point counts). Consequently, 17 of the 39 bird species differed between the two route types in frequency of occurrence and relative abundance, measured using an indicator species analysis. Six species, including five obligate grassland species, were more prevalent at off-road sites; they included four species listed under the Canadian federal Species At Risk Act or listed by the Committee on the Status of Endangered Wildlife in Canada: Sprague's Pipit (Anthus spragueii), Baird's Sparrow (Ammodramus bairdii), the Chestnut-collared Longspur (Calcarius ornatus), and McCown's Longspur (Rhynchophanes mccownii). The six species were as much as four times more abundant on off-road sites. Species more prevalent along roadside routes included common species and those typical of farmland and other human-modified habitats, e.g., the European Starling (Sturnus vulgaris), the Black-billed Magpie (Pica hudsonia), and the House Sparrow (Passer domesticus). Differences in avian community composition between roadside and off-road surveys suggest that the use of BBS data when generating population estimates or distribution models may overestimate certain common species and underestimate others of conservation concern. Our results highlight the need to develop appropriate corrections for bias in estimates derived from roadside sampling, and the need to design surveys that sample bird communities across a more representative cross-section of the landscape, both near and far from roads.

Rangeland Health Assessment: A Useful Tool for Linking Range Management and Grassland Bird Conservation?

Large-scale loss and degradation of North American native prairie coupled with sharp declines in grassland bird populations call for a clear understanding of the effects of livestock production on bird habitat selection. Grassland birds typically select breeding habitat based on a suite of structural and community vegetation features shaped by grazing. Rangeland health indices are a tool for assessing grassland structure and community composition that may offer biologists and range managers common language to achieve grassland bird recovery goals. We used point-count surveys, vegetation measures, and indices of rangeland health to examine bird-habitat relationships on native grassland in southwestern Saskatchewan for 10 grassland bird species. We used an information theoretic approach to compare the support of three hypotheses explaining variation in bird abundance as a function of local vegetation characteristics: bird abundance is best explained by 1) vegetation structure, 2) vegetation structure heterogeneity, or 3) plant community. Vegetation structure variables were present in top-ranking models (i.e., models within four Akaike information criterion units of top model) for eight species and solely comprised top-ranking models for Baird’s sparrow (Ammodramus bairdii), chestnut-collared longspur (Calcarius ornatus), horned lark (Eremophila alpestris), McCown’s longspur (Rhynchophanes mccownii), and savannah sparrow (Passerculus sandwichensis). Structural heterogeneity variables were present in top-ranked models for grasshopper sparrow (Ammodramus savannarum), horned lark (Eremophila alpestris), and western meadowlark (Sturnella neglecta). Plant composition variables solely comprised top-ranking models for clay-colored sparrow (Spizella pallida) and were present in top-ranked models for grasshopper sparrow and vesper sparrow (Pooecetes gramineus). Our results indicate that vegetation structure variables, namely litter mass, vegetation volume, and bare ground cover, best explain variation in bird abundance. Although the rangeland health index received little support as a predictor of bird abundance, vegetation structure components of the index could be used to communicate grazing management guidelines that maintain grassland bird habitat.

Associations of Grassland Bird Communities with Black‐Tailed Prairie Dogs in the North American Great Plains

Colonial burrowing herbivores can modify vegetation structure, create belowground refugia, and generate landscape heterogeneity, thereby affecting the distribution and abundance of associated species. Black-tailed prairie dogs (Cynomys ludovicianus) are such a species, and they may strongly affect the abundance and composition of grassland bird communities. We examined how prairie dog colonies in the North American Great Plains affect bird species and community composition. Areas occupied by prairie dogs, characterized by low percent cover of grass, high percent cover of bare soil, and low vegetation height and density, supported a breeding bird community that differed substantially from surrounding areas that lacked prairie dogs. Bird communities on colony sites had significantly greater densities of large-bodied carnivores (Burrowing Owls [Athene cunicularia], Mountain Plovers, [Charadrius montanus], and Killdeer [Charadrius vociferus]) and omnivores consisting of Horned Larks (Eremophila alpestris) and McCown's Longspurs (Rhynchophanes mccownii) than bird communities off colony sites. Bird communities off colony sites were dominated by small-bodied insectivorous sparrows (Ammodramus spp.) and omnivorous Lark Buntings (Calamospiza melanocorys), Vesper Sparrows (Pooecetes gramineus), and Lark Sparrows (Chondestes grammacus). Densities of 3 species of conservation concern and 1 game species were significantly higher on colony sites than off colony sites, and the strength of prairie dog effects was consistent across the northern Great Plains. Vegetation modification by prairie dogs sustains a diverse suite of bird species in these grasslands. Collectively, our findings and those from previous studies show that areas in the North American Great Plains with prairie dog colonies support higher densities of at least 9 vertebrate species than sites without colonies. Prairie dogs affect habitat for these species through multiple pathways, including creation of belowground refugia, supply of prey for specialized predators, modification of vegetation structure within colonies, and increased landscape heterogeneity.

Taxonomic recommendations for British birds: Sixth report

Taxonomic recommendations for British birds: Sixth report

Avian response to vegetative pattern in playa wetlands during winter

Breeding-bird communities inhabiting northern prairie wetlands have been shown to have higher densities and diversities in wetlands with a well-interspersed 50:50 vegetative cover:water ratio than in those wetlands with a higher or lower proportion of cover. Potential reasons for such a response include increased food or visual isolation and spacing of breeding birds. We manipulated cover:water ratios (75:25, 50:50, 25:75) in Southern Great Plains playas and examined avian response (i.e., species richness, non-waterfowl bird density, and waterfowl density) to these patterns in winter. We found the highest species richness and generally the highest waterfowl densities in the 50:50 cover:water treatment. Because the amount of vegetative food was similar among treatments and waterfowl inhabiting playas during winter are forming pair bonds, it is most likely that the optimal edge and visual isolation provided in the 50:50 cover:water treatment contributed to its high use and richness. Nonwaterfowl bird density was not different among the treatments. Many nonwaterfowl birds using playas in winter, such as McCown's longspur (Calcarius mccownii), occur as nonbreeding feeding flocks, are not forming pair bonds, and likely are not responding to particular cover:water treatments. Playa wetland biologists should create a well-interspersed 50:50 cover:water ratio to optimize waterfowl use and avian species richness.

Occurrence and productivity of songbirds in prairie farmland under conventional versus minimum tillage regimes

Abundance and productivity of common bird species in prairie cropland under either conventional or minimum tillage were examined in southern Alberta, Canada. Cover types included spring cereals, winter wheat and summerfallow. Productivity was assessed using observations of nesting and brood-rearing behavior. Five species were sufficiently abundant to allow for some statistical analyses: horned lark ( Eremophila alpestris), savannah sparrow ( Passerculus sandwichensis), Baird’s sparrows ( Ammodramus bairdii), chestnut-collared longspur ( Calcarius ornatus) and McCown’s longspur ( Calcarius mccownii). Abundance varied between conventional and minimum tillage regimes for most species in at least one cover type. Savannah sparrows in spring cereal and winter wheat and chestnut-collared longspurs in summerfallow tended to prefer minimum tillage. McCown’s longspurs and horned larks occurred more frequently on conventional than minimum till spring cereal plots in at least 1 of the 2 years. For savannah sparrows, minimum till spring cereal and winter wheat were more productive than conventional till habitat. Summerfallow of either tillage regime did not appear to be as productive as minimum till cereal fields for this species. Chestnut-collared longspurs occurred predominantly in minimum till summerfallow and spring cereal habitat and showed almost no productivity in conventionally managed plots. McCown’s longspurs tended to have higher productivity in minimum till plots. Horned larks had high productivity in minimum till winter wheat in 1996. Male Baird’s sparrows occupied territories in minimum till winter and spring cereal fields in 1995, but did not attract mates; they were not detected in 1996. Minimum tillage appeared to confer benefits in productivity to species that nested in farmland.

Longspurs and snow buntings: phylogeny and biogeography of a high-latitude clade ( Calcarius)

Using complete cytochrome b sequence data, we determined that the genus Calcarius, as presently recognized, is paraphyletic. Calcarius plus Plectrophenax form a highly supported clade composed of two subclades, a “snow bunting” clade comprised of Plectrophenax plus Calcarius mccownii (formerly in the monotypic genus Rhynchophanes), and a “collared” longspur clade of Calcarius lapponicus, ornatus, and pictus. Contrary to conventional thought, Calcarius is not phylogenetically close to either Calamospiza or Emberiza. Unlike these two genera, the taxonomic affinities of Calcarius appear to lie outside of the sparrow (tribe Emberizini) assemblage. Calcarius appears to be a relatively old songbird lineage, originating between 4.2 and 6.2 million years ago. Within Calcarius, pictus and ornatus form a closely related sister pair (2.9% divergent), as do Calcarius nivalis and hyperboreus (0.18% divergent). The group ( Calcarius, sensu lato) is inferred to have its origins at relatively high latitudes in the New World.

Relationship between Testis Size and Mating Systems in American Sparrows (Emberizinae)

Relationship between Testis Size and Mating Systems in American Sparrows (Emberizinae)

The Hazards of Nesting near Shrubs for a Grassland Bird, the McCown's Longspur

The Hazards of Nesting near Shrubs for a Grassland Bird, the McCown's Longspur