Conservation of Grassland Bird Populations on Military Installations in the Eastern United States with Special Emphasis on Fort Campbell Army Base, Kentucky

Grassland bird populations have decline significantly over the past 30 years because of the dramatic decrease of native grasslands through clearing of non-forested land for agriculture, and discontinued use of fire. It is imperative to understand the distribution and productivity of these birds and the potential for grassland management to enhance these declining populations, especially in land areas where the landuses may be compatible with grassland bird conservation. This study was conducted to provide needed basic life history and nest site habitat use information as well as information about populations and potential region-wide habitat availability to enhance current and future land management planning. This stydy focused on Grasshopper Sparrows (Ammodramus savannarum), Henslow’s Sparrows (Ammodramus henslowii), Field Sparrows (Spizella pusillia), Dickcissels (Spiza Americana), and Eastern Meadowlarks (Sturnella magna) The specific objectives of this project were: 1) to provide basic life history parameters for five species of conservation concern at Fort Campbell Army Base, Kentucky, over a five-year period (1999-2003; Chapter 2); 2) to use the basic life history parameters to examine population viability grassland bird populations at Fort Campbell, and examine the implications of management activities within the breeding season on these population viabilities (Chapter 3); 3) to examine nest site habitat selection of the five focal species (Chapter 4); and 4) to examine the potential for US Department of Defense installations in the eastern US to provide grassland habitat for breeding and wintering grassland bird populations (Chapter 5). Finally, in Chapter 6, I discuss the management implications developed from the results of this project. A total of 811 nests of target species were monitored between 1999-2003, and nest success ranged between 14.7% and 33.8% for each species. Most nest failures were attributed to predation. Brown-Headed Cowbird (Molothrus ater) nest parasitism rates were very low for all species. Clutch size decreased during the nesting season for Dickcissels, Grasshopper Sparrows, and Field Sparrows. Nesting phenology suggests the possibility of at least double-brooding for all five species in this study. Eastern Meadowlarks initiated nests earliest, mid-April. Field Sparrow nest initiation started the next week, followed by Henslow’s Sparrows the next week, and then Grasshopper Sparrows. Dickcissels were consistently the last species to arrive and began nesting during the second week of May. For all species, nest initiation continued through mid-July, and nesting activity continued through August. This study provided the biological parameters necessary to create population models to evaluate population trajectories and alternative management plans. I constructed a simple population model incorporating typical demographic parameters collected in the field supplemented by values found in the literature for Henslow’s Sparrows, Grasshopper Sparrows, Dickcissels, Eastern Meadowlarks and Field Sparrows. Species specific parameters collected in the field included clutch size, nesting phenology, Mayfield (1975) nesting success, and number of fledglings per successful nest. This analysis produced population viability plots with curves representing the threshold between source and sink populations. I also modeled the effects of breeding season length and hay management within the nesting season on the number of possible nesting attempts to examine the population trajectories of Grasshopper Sparrows and Henslow’s Sparrows. For Henslow’s Sparrows (triple-brooded, 4 attempts), the basic model using the mean estimates of nest success and young per successful nest for all years combined indicated the population could not sustain itself without immigration. The estimates of nesting success and young produced per successful nest for 2 of the 5 years (2001 and 2003) indicated source populations with 4 nesting attempts (A) and 3 years (1999, 2000 and 2002) indicated sink populations. For Grasshopper Sparrows (triple-brooded) population viability for 3 of the 5 years (2000, 2002 and 2003) indicated source populations with 4 nesting attempts (A) and 2 years (1999 and 2001) indicated sink populations. For Dickcissels (single-brooded), Field Sparrows (double-brooded), and Eastern Meadowlarks (double-brooded), the mean estimates of nest success and young per successful nest for all years combined were too low to indicate any source populations under the conditions of this model. For Dickcissels, the estimates of nest success and young per successful nest for any single year were also too low to indicate any source populations under the conditions of this model. For Grasshopper Sparrows, the mowing model indicated “No mowing” and mowing after 1 August allowed for the possibility of a source population with the overall estimates of nest success and young produced per successful nest. Point-estimates for 1999, 2001, and 2002 indicated source populations only with no mowing. Mowing on 15 June or after 15 July allowed the Grasshopper Sparrow population in 2000 to be a source, whereas mowing 15 May, 1 June, and 1 July caused sink populations under the model assumptions. In 2003, the nesting success rate and the number of young produced per successful nest were great enough to compensate for mowing after 15 Jul with maximum breeding effort. For Henslow’s Sparrows, mowing before 15 July indicated sink populations in all years (Figure 3-15). The “no mowing” threshold did not allow a possible source population for the nesting success and young per successful nest estimates for all years combined with maximum breeding effort, but the variation indicated “no mowing” may allow for a source population. In 1999, 2000, and 2002, under conditions for maximum breeding output the estimates indicated a sink population even with no mowing. Year 2003 was a source population only with “no mowing.” Mowing after 1 August allowed the 2001 population to be a source. I examined habitat differences between selected nest sites and available habitats (univariate analysis), and examined microhabitat selection (niche) relationships among the five target species (multivariage analysis). Based on the univariage analysis, litter depth was significantly greater at the nest sites for all species than at the random sites. The random sites also had greater bare ground cover and lower grass height than all species except Grasshopper Sparrows. Henslow’s Sparrow nest sites had the greatest warm-season grass cover and Eastern Meadowlark nest sites had the greatest cool-season grass cover. Field Sparrow nest sites had the greatest cover in woody vegetation. Based on the multivariate analysis, Field Sparrows and Dickcissels were using similar habitats; the discriminant function analysis had difficulty separating the nest sites of these species. The random vegetation plots, representing available microhabitat at Fort Campbell, were centrally located when plotted using the discriminant function coefficients calculated with the vegetation measurements at the nest sites of the five grassland species. Thus available habitat, on average, had intermediate litter depth and vertical cover, and relatively high forb cover and low warm-season grass cover. The random locations also occupied a relatively large area in the multivariate space, and extended well beyond the area of overlap of the five species along the second discriminant function axis. This result demonstrated that available habitat included unsuitable areas of grassland habitat for these five species. In a large potion of the random areas, burning occurred annually, which was too frequent to create suitable habitat for these grassland species of high conservation concern. Finally, I used a course-filter analysis to determine which military installations in the eastern United States have the potential to provide significant grassland habitat by identifying military installations that contain large (\u3e40 ha) grassland patches in the eastern US, identifying areas where open habitats (e.g., grassland, hayfields, agriculture) occupy a significant portion of the landscape, and overlaying the areas of high diversity for obligate grassland birds during the breeding and wintering seasons in the eastern US. I also conducted a buffer analysis to determine if the extent of grassland within the military installation was representative of grassland habitat within the surrounding landscape, and determine how much potential the surrounding landscape (within 30 km) had for grassland restoration. Of the 186 land areas in the eastern US managed by the DOD, 45 contained at least one large (\u3e40 ha) patch of grassland, including 1 port managed by the Army Corps of Engineers, 23 Army, 3 Air Force, 3 marine, 11 Navy, and 4 National Guard installations. Military installations with significant grassland habitat were found throughout the eastern US providing at least 65,000 ha of grassland in patches greater than 40 ha. Most of the selected military installations were located in the southern US within 300 km of the coast, and could be especially important for wintering habitat. Military installations could have major positive impacts on the declining populations of bird and other wildlife species, which depend on frequent habitat disturbance to maintain early-successional habitats like grasslands. Because many military activities require or cause the maintenance of large areas of open, grassy or shrubby habitats, tailoring habitat management to enhance grassland populations would not require major changes in existing management plans. The location of some of the larger eastern US military installations in landscapes with relatively large amounts of open habitats may also serve as a refuge for many grassland species displaced by modern, “clean” farming practices. With a few considerations to the type and timing of disturbances, military installations could serve as a model for other federal and private land management for the conservation of grassland habitats, and may even serve as a control sites for comparison with grassland restoration efforts. Military lands comprise over 10-million ha of land in the US and could provide unique management opportunities to provide breeding and wintering habitat for birds. Conservations strategies for grassland species could be developed to take advantage of the unique need for open habitats for military training, especially in the eastern US. Land managers need to understand although grassland habitat used by different species superficially may seem very similar, different management actions will benefit different sets of species and may negatively impact others. Local habitat conditions can influence not only the presence of grassland birds but also other life history parameters like the number of successful broods and the number of nesting attempts. Planning across a temporal gradient is needed to provide suitable habitat for all species of concern

Response of Grassland Birds to Agricultural Intensity at Different Spatial Scales in Texas

The decline in grassland birds is often associated with habitat loss due to intensity of conversion to agricultural lands and the alterations of natural disturbances. We sought to identify agricultural effects at differing scales that correlate to Texas grassland bird abundance, especially northern bobwhite (Colinus virginianus). Ninety-five roadside routes were surveyed in 20 Texas counties ranging from the Oklahoma border to the coastal plains. We conducted point counts in May and June from 2013 to 2016. To estimate the coarse effects of agriculture on bird abundance at a county level, we used number of cattle and area of farmland used per crop type amongst other data from the National Agriculture Statistics Service (NASS, 2012) for analyses. For estimates at finer scales, including the scale of individual routes and points, we obtained annual agricultural data and GIS layers from the NASS. We determined the predictive ability of each agricultural type via linear models and stepwise selection. From 2013 to 2016, we detected 32,373 individual birds, including 5,329 northern bobwhite, from 150,423 point count surveys. Our preliminary results revealed that agriculture only affects a few species at a county level. The top models for rufous-crowned sparrows (Aimophila ruficeps) and field sparrows (Spizella pusilla) included only one predictor from the full model - the number of cattle per county (R2 = 0.10; R2 = 0.29). The top model for yellow-billed cuckoos (Coccyzus americanus) included cattle per county and year, while the best model was found for dickcissels (Spiza americana), which included year and the proportions of woodland agriculture and pasture (R2 = 0.23; R2 = 0.33). While our results may indicate that agriculture impacts some species on coarse scales, it appears that bobwhite are likely impacted only on smaller scales and further analysis will be needed to identify specific impacts of agriculture on these scales

Utility of Fine Resolution Land Cover Data for Modeling Northern Bobwhite Abundance in the Oaks and Prairies of Oklahoma

Management of northern bobwhite (Colinus virginianus) requires landscape-level planning to promote sustainable populations. Limitations in time and resources necessitate the use of large geographic datasets to efficiently evaluate habitat suitability across landscapes. Many such datasets, however, are limited by a lack of detailed and current information relevant to regional management efforts. To meet this need, regional partners recently released the Oklahoma Ecological Systems Mapping (OESM) product, which offers high spatial and thematic resolution vegetation data, current to 2015. We evaluated the utility of the new OESM product for modelling abundance of northern bobwhite and other grassland birds, relating percent cover types to bird survey data from the Oaks and Prairies Joint Venture. Using an information-theoretic approach (AIC), we compared the performance of OESM to the more widely known National Land Cover Dataset (NLCD). The OESM data provided information on 20 land cover types at 10-m resolution compared 7 types and 30-m resolution for NLCD. We conducted a total of 2,367 individual counts for breeding birds from May–July, 2014–2016, across 10 counties in the Oklahoma Oaks and Prairies ecoregion. We used generalized linear mixed models to control for random effects of year and AICc to evaluate model performance. OESM models vastly outperformed NLCD for 6/7 species (AIC weights \u3e0.99). Northern bobwhite was the only species where NLCD was the highest performing model. These results suggest that, in contrast to other grassland species, added levels of habitat complexity do not inform our ability to model local bobwhite abundance

Strategic Habitat Conservation for Declining Grassland Wildlife Populations in the Oaks and Prairies Joint Venture

Degradation and conversion of functioning grassland ecosystems in North America has driven significant declines in grassland wildlife populations across multiple taxa. In an effort to address declines in the grasslands of Oklahoma and Texas, a number of governmental agencies and Non-Governmental Organizations have partnered to form the Oaks and Prairies Joint Venture (OPJV) to more strategically and collaboratively deliver conservation actions in this region. With northern bobwhite (Colinus virginianus) as the flagship species, OPJV has worked to implement a fully integrated Strategic Habitat Conservation framework that works at multiple scales to conduct biological planning, landscape conservation design, habitat tracking and population monitoring in support of conservation efforts aimed at restoring not just northern bobwhite, but a variety of bird and pollinator species that depend on healthy grasslands. The signature conservation delivery program of this effort was the Grassland Restoration Incentive Program (GRIP) which has improved habitat for grassland wildlife on over 24,300 hectares of working lands in focus areas throughout the OPJV geography since it was created in 2013. The Grassland Restoration Incentive Program was accompanied by a full complement of conservation delivery programs that support prescribed burning associations and other landowner cooperatives, utilize market-based conservation delivery strategies, and implement strategic outreach and communications. The conservation efforts were supported by over 4,500 point counts annually in National Bobwhite Conservation Initiative Coordination Implementation Program focal areas as well as 7 focal regions, each comprising clusters of 2-8 counties. Combining the efforts of multiple partners ties the range-wide population and habitat objectives with on-the-ground conservation actions for quail, other grassland birds, butterflies, and grassland pollinators

Data-driven Planning for the Conservation of Grassland Birds in the Central Hardwoods Bird Conservation Region

The Central Hardwoods Joint Venture held two workshops in 2006 to delineate bobwhite focus areas across the Central Hardwoods Bird Conservation Region (BCR) for targeting on-the-ground conservation efforts. From 2008 – 2012, we conducted randomized sets of point counts within counties containing bobwhite focal areas to assess the efficacy of that method for monitoring grassland birds within focal areas, and to assess relationships of conservation practices with bird species occupancy and abundance. We collected data on nine species of Partners in Flight priority species, including northern bobwhite (Colinus virginianus). Land cover types within a 200-m buffer of each point were derived from year National Agricultural Statistics Service data, and information related to the location of conservation practices deemed beneficial to grassland birds was attained from the National Resources Conservation Service. We fit occupancy and abundance models for each species using Akaike’s Information Criterion adjusted for small sample sizes. We then used the model covariates to map predicted abundances of three species, northern bobwhite, eastern meadowlark (Sturnella magna), and Henslow’s sparrow (Ammodramus henslowii) across the BCR. The spatial patterns of predicted abundance varied among species, suggesting that focus areas should be somewhat species-specific. We will use data collected around the nests of each species at Ft. Campbell, a military base straddling the Kentucky-Tennessee border where grassland management has occurred at relatively large scales over more than two decades, to assess the with-in patch structure preferred by each species to develop grazing practices that will result in the desired structure for the species suite