Grassland Songbirds In A Dynamic Management Landscape: Behavioral Responses And Management Strategies

In recent decades, earlier and more frequent harvests of agricultural grasslands have been implicated as a major cause of population declines in grassland songbirds. From 2002 to 2005, in the Champlain Valley of Vermont and New York, USA, we studied the reproductive success of Savannah Sparrows (Passerculus sandwichensis) and Bobolinks (Dolichonyx oryzivorus) on four grassland treatments: (1) early-hayed fields cut before 11 June and again in early- to mid-July; (2) middle-hayed fields cut once between 21 June and 10 July; (3) late-hayed fields cut after 1 August; and (4) rotationally grazed pastures. Both the number of fledglings per female per year and nest success (logistic-exposure method) varied among treatments and between species. Although birds initiated nests earlier on early-hayed fields compared to others, haying caused 99% of active Savannah Sparrow and 100% of active Bobolink nests to fail. Both the initial cutting date and time between cuttings influenced renesting behavior. After haying, Savannah Sparrows generally remained on early-hayed fields and immediately renested (clutch completion 15.6 ± 1.28 days post-haying; all values are reported as mean 6 SE), while Bobolinks abandoned the fields for at least two weeks (mean clutch completion 33 ± 0.82 days post-haying). While female Savannah Sparrows fledged more offspring per year (1.28 ± 0.16) than female Bobolinks (0.05 6 0.05), reproductive success on early-hayed fields was low. The number of fledglings per female per year was greater on middle-hayed fields (Savannah Sparrows, 3.47 ± 0.42; Bobolinks, 2.22 ± 0.26), and late-hayed fields (Savannah Sparrows, 3.29 ± 0.30; Bobolinks, 2.79 ± 0.18). Reproductive success was moderate on rotationally grazed pastures, where female Savannah Sparrows and female Bobolinks produced 2.32 ± 0.25 and 1.79 ± 0.33 fledgling per year, respectively. We simultaneously conducted cutting surveys throughout the Champlain Valley and found that 3–8% of hayfield habitat was cut by 1–4 June, 25–40% by 12–16 June, and 32–60% by 28 June–2 July. Thus, the majority of grassland habitat was cut during the breeding season; however, late-hayed fields served as high-quality reserves for late-nesting female Bobolinks that were displaced from previously hayed fields. For fields first cut in May, a 65-day interval between cuts could provide enough time for both species to successfully fledge young

Grassland Songbird Survival And Recruitment In Agricultural Landscapes: Implications For Source-Sink Demography

Population growth and decline are particularly sensitive to changes in three key life-history parameters: annual productivity, juvenile survival, and adult survival. However, for many species these parameters remain unknown. For example, although grassland songbirds are imperiled throughout North America, for this guild, only a small number of studies have assessed these parameters. From 2002 to 2006, in the agricultural landscape of the Champlain Valley of Vermont and New York, USA, we studied Savannah Sparrow (Passerculus sandwichensis) and Bobolink (Dolichonyx oryzivorus) demography on four grassland treatments: (1) early-hayed fields cut before 11 June and again in early- to mid-July; (2) middle-hayed fields cut once between 21 June and 10 July; (3) late-hayed fields cut after 1 August; and (4) rotationally grazed pastures. We assessed whether these treatments affected adult apparent survival (φ) and recruitment (ƒ ), how sensitive these parameters were to the presence of nonbreeders and local dispersal, and the populations’ ability to persist in these four habitats. On average, birds using late-hayed fields had \u3e25% higher apparent survival than those on the more intensively managed early-hayed, middle-hayed, and grazed fields. Overall male φ was 35% higher than female φ, and Savannah Sparrow φ was 44% higher than Bobolink φ. Across all analyses and treatments, apparent survival estimates were 0.58–0.85 for male and 0.48–0.71 for female Savannah Sparrows, and 0.52–0.70 for male and 0.19–0.55 for female Bobolinks. For males of both species, potential nonbreeders decreased the precision of and lowered apparent survival estimates by 25%; female estimates showed little variation with the inclusion of nonbreeders. Inclusion of local dispersal observations increased apparent survival estimates and, in many cases, increased precision, though the effect was stronger for Savannah Sparrows than for Bobolinks, and also stronger for males than for females. High Savannah Sparrow apparent survival rates resulted in stable or near stable populations (λ ≈ 1), particularly in late-hayed and grazed fields, while low Bobolink apparent survival rates resulted in strongly declining populations (λ \u3c 1) in all treatments

Carbon storage, timber production, and biodiversity: Comparing ecosystem services with multi-criteria decision analysis

Increasingly, land managers seek ways to manage forests for multiple ecosystem services and functions, yet considerable challenges exist in comparing disparate services and balancing trade-offs among them. We applied multi-criteria decision analysis (MCDA) and forest simulation models to simultaneously consider three objectives: (1) storing carbon, (2) producing timber and wood products, and (3) sustaining biodiversity. We used the Forest Vegetation Simulator (FVS) applied to 42 northern hardwood sites to simulate forest development over 100 years and to estimate carbon storage and timber production. We estimated biodiversity implications with occupancy models for 51 terrestrial bird species that were linked to FVS outputs. We simulated four alternative management prescriptions that spanned a range of harvesting intensities and forest structure retention. We found that silvicultural approaches emphasizing less frequent harvesting and greater structural retention could be expected to achieve the greatest net carbon storage but also produce less timber. More intensive prescriptions would enhance biodiversity because positive responses of early successional species exceeded negative responses of late successional species within the heavily forested study area. The combinations of weights assigned to objectives had a large influence on which prescriptions were scored as optimal. Overall, we found that a diversity of silvicultural approaches is likely to be preferable to any single approach, emphasizing the need for landscape-scale management to provide a full range of ecosystem goods and services. Our analytical framework that combined MCDA with forest simulation modeling was a powerful tool in understanding trade-offs among management objectives and how they can be simultaneously accommodated. © 2012 by the Ecological Society of America

SQLite database to accompany the paper, "Statistical learning mitigation of false positives from template-detected data in automated acoustic wildlife monitoring"

This dataset is a SQLite database that accompanies methods and analysis described in the paper, "Statistical learning mitigation of false positives from template-detected data in automated acoustic wildlife monitoring" (Balantic & Donovan 2019, Bioacoustics, https://www.tandfonline.com/doi/full/10.1080/09524622.2019.1605309). A Github repository containing code for using the SQLite database also accompanies this paper at: http://github.com/cbalantic/false-positive-mitigatio

Evaluation of the Bird Conservation Area Concept in the Northern Tallgrass Prairie: Annual Report 2001

In 1998 we initiated a test of the concept that Bird Conservation Areas (BCA\u27s) can maintain populations of breeding grassland birds. The underlying hypothesis is that large core areas of quality habitat (such as native prairie) that are surrounded by neutral habitats (such as small-grain fields), and that are isolated from hostile habitats (such as woody vegetation) will result in avian densities and reproductive rates sufficient to at least maintain population levels of breeding birds. This concept was proposed by the Midwest Working Group of Partners In Flight (e.g., Pashley and Fitzgerald 1996) and endorsed also by the Prairie Pothole Joint Venture of the North American Waterfowl Management Plan. This evaluation is being conducted in the northern tallgrass prairie, but the concept may be more generally applicable. In 1999, we added 11 study plots in Sheyenne National Grassland in southeastern North Dakota to the existing 33 study plots in northwestern Minnesota. All study plots were assigned to one of four categories: 1) small core area surrounded by neutral landscape, 2) small core area surrounded by hostile landscape, 3) large core area surrounded by neutral landscape, and 4) large core area surrounded by hostile landscape. This year, four of the study plots could not be censused or nest-searched because prairies received prescribed burning. On each of the remaining 40 study plots we collected data on population density of breeding birds by censusing each plot twice during the field season. Data on nesting success, predation, and brood parasitism were obtained from a subset of 29 study plots. In addition, we color-banded birds on four of the study plots, focusing on Clay-colored Sparrow, Savannah Sparrow, and Bobolink. In 2001, we recorded 58 species on our census plots (compared with 41, 53, and 54 in 1998, 1999, and 2000 respectively), found 838 nests of 41 species (compared with 293 of 19 species, 793 of 34 species, and 679 of 39 species in 1998, 1999, and 2000), and color-banded 318 birds (compared with 263 and 334 in 1999 and 2000)

Patch Size and Landscape Effects on Density and Nesting Success of Grassland Birds

Cumnt management recommendations for grassland birds in North America emphasize providing large patches of grassland habitat within landscapes that have few forest or shrubland areas. These Bird Conservation Areas are being proposed under the assumption that large patches of habitat in treeless landscapes will maintain viable populations of grassland birds. This assumption requires that patch size and landscape features affect density and nesting success of grassland birds, and that these effects are consistent among years and regions and across focal species. However, these assumptions have not yet been validated for grassland binls, and the relative importance of local vegetation structure, patch size, and landscape composition on grassland bird populations is not well known. In addition, factors influencing grassland bird nesting success have been investigated mostly in small-scale and short-duration studies. To develop management guidelines for grassland birds, we tested the spatial and temporal repeatability of the influence of patch size and landscape composition on density and nesting success of 3 grassland passerines, after controlling for local-scale vegetation structure, climate, and- when analyzing nest successbird density. We conducted our study during 4 years (1998-2001) in 44 study plots that were set up in 3 regions of the northern tallgrass prairie in Minnesota and North Dakota, USA. In these study plots we measured density and nesting success of clay-colored sparrows (Spizella pallida), Savannah sparrows (Passerculus sandwichensis), and bobolinks (Dolichonyx olyzivorus). Statistical models indicated that density was influenced by patch size, landscape, region, and local vegetation structure more so than by local vegetation structure alone. Both magnitude and direction of the response of density to patch size varied among regions, years, and species. In contrast, the direction of landscape effects was consistent among regions, years, and between Savannah sparrows and bobolinks. In each species, this landscape effect was independent of patch size. Nesting success was not cleariy influenced by patch size or landscape composition, and none of the factors that influenced avian density also influenced nesting success in any of the 3 species. General statements on optimal habitat for grassland birds should therefore be viewed cautiously. Instead, long-tern studies in different regions as well as a deeper understanding of the local system are needed to determine which factors are most important for grassland birds in a particular are

AMModels: An R package for storing models, data, and metadata to facilitate adaptive management

<div><p>Agencies are increasingly called upon to implement their natural resource management programs within an adaptive management (AM) framework. This article provides the background and motivation for the R package, <b>AMModels</b>. AMModels was developed under R version 3.2.2. The overall goal of <b>AMModels</b> is simple: To codify knowledge in the form of models and to store it, along with models generated from numerous analyses and datasets that may come our way, so that it can be used or recalled in the future. <b>AMModels</b> facilitates this process by storing all models and datasets in a single object that can be saved to an .RData file and routinely augmented to track changes in knowledge through time. Through this process, <b>AMModels</b> allows the capture, development, sharing, and use of knowledge that may help organizations achieve their mission. While <b>AMModels</b> was designed to facilitate adaptive management, its utility is far more general. Many R packages exist for creating and summarizing models, but to our knowledge, <b>AMModels</b> is the only package dedicated not to the mechanics of analysis but to organizing analysis inputs, analysis outputs, and preserving descriptive metadata. We anticipate that this package will assist users hoping to preserve the key elements of an analysis so they may be more confidently revisited at a later date.</p></div

Habitat Use Patterns of Bobolinks and Savannah Sparrows in the Northeastern United States

In the northeastern United States, grassland birds regularly use agricultural fields as nesting habitat. However, birds that nest in these fields regularly experience nest failure as a result of agricultural practices, such as mowing and grazing. Therefore, information on both spatial and temporal patterns of habitat use is needed to effectively manage these species. We addressed these complex habitat use patterns by conducting point counts during three time intervals between May 21, 2002 and July 2, 2002 in agricultural fields across the Champlain Valley in Vermont and New York. Early in the breeding season, Bobolinks (Dolichonyx oryzivorus) used fields in which the landscape within 2500 m was dominated by open habitats. As mowing began, suitable habitat within 500 m became more important. Savannah Sparrows (Passerculus sandwichensis) initially used fields that contained a high proportion of suitable habitat within 500 m. After mowing, features of the field (i.e., size and amount of woody edge) became more important. Each species responded differently to mowing: Savannah Sparrows were equally abundant in mowed and uncut fields, whereas Bobolinks were more abundant in uncut fields. In agricultural areas in the Northeast, large areas (2000 ha) that are mostly nonforested and undeveloped should be targeted for conservation. Within large open areas, smaller patches (80 ha) should be maintained as high-quality, late-cut grassland habitat

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The structure of an amModelLib object, consisting of four slots.

<p>The structure of an amModelLib object, consisting of four slots.</p