Grassland Birds

Contributed Paper
ROOM: CC, Room 19

8:10AM Reaping What We Sow: Grassland Bird Community Responses to Conservation Reserve Enhancement Program Practices in Michigan
Andrew J. Dennhardt; Adria S. VanLoan; Gary J. Roloff; Kelly F. Millenbah; Henry R. Campa III
Understanding ecological impacts of farmland set-aside programs on avian communities is important because implementation of such programs provides habitat for grassland dependent species. We evaluated the vegetation and avian communities that occupied Conservation Reserve Enhancement Program (CREP) fields in the Saginaw Bay watershed of Michigan, USA during 2005 and 2006. We measured vegetation composition and structure in CREP CP1 (non-native grasses and legumes) fields and the upland portions of CP23 (wetland restoration, upland areas planted to native vegetation) fields, ranging in size from 6.8 to 23.6 ha. We quantified avian species richness and evenness at multiple spatial scales, and we also estimated abundance using a multispecies hierarchical model while accounting for imperfect species detection. Amount of bare ground, grass cover, and dead vegetation canopy cover differed between native (upland CP23) and non-native (CP1) CREP grasslands. Bare ground and dead canopy cover was 400% and 350% higher in native fields throughout summer, respectively, while grass cover was 50% lower in native fields in early summer. Additionally, grass cover was not different between native and non-native fields by mid- and late-summer. Grasslands in our study were used by most (11 of 15) grassland bird species expected to occur in Michigan, including species of conservation concern. Our best abundance model included a random effect of field on detection probability, a fixed effect of year on abundance, and a fixed effect of field type (i.e., CP23 and CP1) on multispecies abundances. Avian densities for native and non-native fields differed for 2 species (grasshopper sparrow, Ammodramus savannarum, and savannah sparrow, Passerculus sandwichensis). These species were also more abundant on native fields. Our findings suggest that maintenance and enhancement of both area and quality of CREP grasslands, especially diverse native community types, will benefit imperiled grassland bird communities in North America.
8:30AM Does Size Matter: the Ability of Novel Grasslands to Attract Obligate Grassland Birds
Rob Keys; Michael Hindy
In the early 1800s tall grass prairie covered many areas of the upper Midwest United States. Much of this was converted to agricultural purposes as the country grew. Over the last 35 years many projects have reestablished tall grass prairies throughout the region. For years we have believed the restoration of prairies in regions where they once existed would lead to the restoration of the biodiversity of other organisms of the prairie, specifically grassland birds. Our research has monitored novel prairies of various sizes with paired grasslands of other types (former agricultural fields, fallow fields, mowed fields) in the Midwest prairie edge region to determine the extent to which this is viable conclusion. Results indicate novel prairie restorations have the lowest obligate grassland bird biodiversity and birds/point (B/P) (H’ = 0. 068; B/P = 0. 50) when compared to mowed mixed grasslands (H’ = 1. 44; B/P = 4. 02) and Conservation Reserve Program (wildlife) grasslands (H’ = 0. 474; B/P = 2. 60) regardless of the size of the restoration. In many cases these novel prairies are devoid of obligate grassland birds of any type after 10+ years of management. We believe a new paradigm of management is called for to restructure these restored prairie grasslands to meet the needs of birds who have adapted over the last 150 years to a non-prairie structure.
8:50AM The Suitability of Reclaimed Surface Mines for Grassland Bird Conservation in the Midwest
Joseph Lautenbach; Nathan Stricker; Mark Wiley; Laura Kearns
Grassland birds are declining across North America, primarily due to habitat loss and degradation. Public lands can serve as core areas of grassland habitat. In Ohio, these consist of reclaimed surface mines and more traditionally restored grasslands. Reclaimed surface mines consist of large, contiguous grassland habitat composed primarily of non-native cool-season grasses, whereas traditionally restored grasslands are typically composed of native warm-season grasses. Our goal was to establish a baseline population for grassland species in Ohio, compare grassland bird abundances on traditional grasslands to reclaimed surface mines, and gain a better understanding of habitat relationships for a suite of grassland species. We conducted 6-minute point count during surveys May-July from 2010-2013 at 3 traditionally restored grasslands in Marion, Williams, and Wyandot counties and 4 reclaimed mine areas in Belmont, Coshocton, Gallia, and Muskingum counties. We visited each point 3 times and estimated distance to each focal species detected. Additionally, we measured vegetation to understand habitat relationships on reclaimed surface mines. We used distance sampling to estimate abundances using the gdistsamp function in package ‘unmarked’ for program R. We observed our greatest densities of grasshopper sparrow (Ammodramus savannarum; 1.20 birds/ha ± 0.20 SE) and Henslow’s sparrow (Ammodramus henslowii; 2.83 birds/ha ± 0.21 SE) on reclaimed surface mines, whereas dickcissel (Spiza Americana; 0.90 birds/ha ± 0.10 SE) and bobolink (Dolichonyx oryzivorus; 0.12 birds/ha ± 0.02 SE) reached greatest densities on traditionally restored grasslands. We observed similar densities between traditionally restored grasslands and reclaimed surface mines for eastern meadowlark (Sturnella magna). In general, grassland bird abundance increased with increasing grassland and openland cover and decreased with increasing cover of mature and early successional forest surrounding each point. Our data suggest that reclaimed surface mines provide suitable habitat for grassland species such as Henslow’s sparrow and grasshopper sparrow.
9:10AM Home Is Where Habitat Is: Factors Affecting Nest Site Selection and Nest Success of Grassland Bird in South Dakota
Sprih Harsh; Hilary Syvertson; Andrew Gregory
In South Dakota, ring-necked pheasant (Phasianus Colchicus, hereafter pheasant) populations have declined since 1960s. Landscapes in this agricultural system continue to undergo significant change and loss of natural vegetation cover is an ever-increasing threat. Lack of suitable habitat has negatively impacted nest and brood survival which has been implicated as one of the primary causes of pheasant population decline. Therefore, in the spring of 2017 we initiated a study to evaluate drivers of pheasant nest site selection and nest success. We used data from 38 nests of radio marked female pheasants captured in winter 2017 near Huron, South Dakota. We quantified habitat and landscape attributes within 500-m radius of nests and random locations using NASA’s Cropland Data Layer and FRAGSTATS. A logistic regression incorporating vegetation composition, structure, grassland patch size, landscape shape index and largest patch index was used to model nest site selection and nest success. The same variables were tested with MANOVA and post hoc ANOVA for significant difference between nest site and random locations. Significant difference was found between nest sites and non-used random locations in terms of percentage of grassland and landscape configuration (P<0.05). Our result also indicated that nest sites had more vertical structure, more percentage of grassland than did random sites. Results of the regression model indicated that nest sites in large grassland patches and in more connected landscapes had higher success (R2=0.79; P<0.05). Our findings suggest that landscape configuration and composition along with local level habitat characteristics are significant drivers of nest site selection and success. Models incorporating both landscape and site level habitat properties could be used to understand the consequences of changes in landscapes on pheasant populations.
9:30AM Looking at the Bigger Picture: How Availability of Nesting and Brooding Habitat Influences Lek-Site Selection By Lesser Prairie-Chickens
Jackie M. Gehrt; Dan S. Sullins; Dave A. Haukos
Contemporary lesser prairie-chicken (Tympanuchus pallidicinctus) populations have been on the decline since the mid-1980s. In response to these declines, the lesser prairie-chicken was briefly listed as threatened under the Endangered Species Act and numerous conservation efforts were launched to restore population abundance. Despite these conservation measures, local populations have continued to decrease. To better understand the influence of reproductive habitat availability on populations, we quantified the juxtaposition and composition of reproductive habitat in a lek landscape (center of lek out to 5-km). We used data collected from 6 study sites in Kansas and Colorado from 2013-2016 to quantify the amount of available nesting and brooding habitat adjacent to leks, investigate the relationship between reproductive habitat availability and lek attendance by males, and examine vegetation characteristics drive lek attendance. We discovered that 29.6% and 24.6% of locations within 5-km of a lek were available nesting and brooding habitat, respectively. We found that leks attended by the most males were in areas with the greatest proportion of nesting habitat. We found that vegetation structure was the main driver of lek attendance for both sexes of lesser prairie-chicken, which leads us to the conclusion that adequate amounts of reproductive habitat surrounding a lek are strongly related with lek attendance by lesser prairie-chickens. It is known that reproductive success is a major driver of lesser prairie-chicken growth rates. Because our findings address issues that determine the reproductive success of an area, they have the potential to influence management practices to bolster future populations of lesser prairie-chickens.


Contributed Paper
Location: Cleveland CC Date: October 10, 2018 Time: 8:10 am - 9:50 am