Research Article: Influence of the Agricultural Conservation Easement Program wetland practices on winter occupancy of Passerellidae sparrows and avian species richness

Date Published: January 24, 2019

Publisher: Public Library of Science

Author(s): Katharine E. Lewis, Christopher T. Rota, Christopher M. Lituma, James T. Anderson, Daehyun Kim.


Wetlands enrolled in the Agricultural Conservation Easement Program (ACEP) are established as a means of restoring wetland ecosystems and wildlife habitat on private, agricultural land. In West Virginia, USA, ACEP wetlands have never been evaluated to determine how they function as wildlife habitat in comparison to other available wetland habitat in the state. We measured the wintering occupancy of Passerellidae species and apparent avian species richness on ACEP wetlands and a set of reference wetlands located on public land in West Virginia to evaluate if ACEP wetlands are being used similarly by avian species to other available wetland habitat in the state. Apparent avian species richness and the occupancy probability of four Passerellidae species—song sparrows (Melospiza melodia), dark-eyed juncos (Junco hyemalis), swamp sparrows (Melospiza georgiana), and white-throated sparrows (Zonotrichia albicollis)—did not differ between ACEP and reference sites. In addition to other vegetative and habitat associations for each species, dark-eyed junco occupancy was negatively correlated with wetland size while swamp sparrow occupancy and apparent avian species richness were positively associated with wetland size. These results indicate that ACEP wetlands are providing winter avian habitat as well as another source of wetland habitat in the state. Maintaining and expanding ACEP wetlands in West Virginia would continue to provide wetland systems in areas that are otherwise lacking these habitats.

Partial Text

In North America, >50% of wetlands have been lost to drainage, urban development and agricultural development over the last 200 years [1]. Remaining wetlands are often exposed to agricultural runoff and physical impacts from livestock grazing [2]. Because wetlands provide important ecosystem services [3–6], including providing wildlife habitat [7], many wetland conservation programs and policies in the U.S. are aimed at reversing past losses [7]. One of these initiatives, the Agricultural Conservation Easement Program (ACEP; formerly the Wetland Reserve Program) is a platform administered through the United States Department of Agriculture’s Natural Resources Conservation Service (NRCS). This program provides financial and technical assistance to landowners in restoring wetlands on their property across the United States by purchasing and administering conservation easements. The objectives of ACEP wetland easements are to provide wetland ecosystem services in agricultural areas, including the creation of wildlife habitat [8]. Since its inception in 1996, over 500,000 ha of wetlands have been restored or created through this program [9]. Between 1996 and 2012, 24 conservation easements were enrolled in the Wetland Reserve Program and ACEP in West Virginia, USA, totaling approximately 179 ha of wetlands.

We surveyed 197 total points on 20 ACEP and 13 reference sites over both survey years, with 118 point counts on ACEP sites (x¯ = 4 surveys per site, se = 0.51, min = 1, max = 9) and 79 point counts on reference sites (x¯ = 4 surveys per site, se = 0.50, min = 1, max = 7). Over the two survey winters, we detected 61 avian species overall, 10 of which were Passerellidae sparrows. Over both survey years and between ACEP and reference sites, we detected song sparrows most often out of the Passerellidae species (n = 547 detections), followed by white-throated sparrows (n = 166), dark-eyed juncos (n = 134), and swamp sparrows (n = 68). All Passerellidae species were detected on both ACEP and reference sites except for American tree sparrow (Spizella arborea), fox sparrow (Passerella iliaca), Savannah sparrow (Passerculus sandwichensis), and white-crowned sparrow (Zonotrichia leucophrys), which were detected only at ACEP sites (Table 2). We report results only from models with the lowest WAIC score (Tables 3–6).

We found that, after controlling for environmental variables, Passerellidae sparrows have similar site occupancy probabilities between ACEP wetlands on private agricultural property and reference wetlands on public lands. Further, we found no differences in overall species richness between ACEP and reference wetlands. This suggests that ACEP wetlands functionally provide similar habitat for wintering avifauna as publicly owned wetlands in West Virginia, even though ACEP wetlands were located primarily in open, agricultural areas and reference wetlands were located largely in forested areas. This indicates that ACEP wetlands in West Virginia are meeting program objectives and acting as an additional source of valuable wildlife habitat. In West Virginia, ACEP is the only conservation program that targets private, agricultural land and therefore provides a unique mechanism for restoring wetlands back on the landscape. Our findings are consistent with other studies comparing wildlife use of created or restored wetlands to naturally occurring wetlands [10–12]. Balcombe et al. [12] found avian abundance and richness were similar between mitigated and reference sites in the spring in West Virginia. Similarly, breeding bird abundance did not differ between restored and naturally occurring wetlands in New York, USA [43].




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