Southeastern Naturalist W.E. Ricks, R.J. Cooper, W.D. Gulsby, and K.V. Miller 2016 Vol. 15, No. 1 162 2016 SOUTHEASTERN NATURALIST 15(1):162–174 Songbird Use of White-tailed Deer (Odocoileus virginianus) Food Plots in Appalachian Hardwood Forests Wilson E. Ricks1, Robert J. Cooper2, William D. Gulsby3,*, and Karl V. Miller2 Abstract - Food plots are commonly planted for Odocoileus virginianus (White-tailed Deer) in the eastern US, because they are known to benefit this species. We hypothesized that food plots may also provide early-successional habitat for nongame species, such as songbirds, in areas where it is normally lacking. Thus, we evaluated songbird use of food plots planted with Trifolium spp. (perennial clovers) in the northern and southern Appalachian Mountains by comparing avian species richness and abundance within plots, along their edges, and in the adjacent forest. During the breeding season on northern sites, there was no difference in avian richness or abundance among the plots, their edges, or adjacent forest. However, both species richness and abundance were greater along plot edges during breeding season on southern sites. Species richness was also greater along plot edges for a subset of southern sites sampled during winter. Thus, food plots within southern Appalachian hardwood forests enhanced habitat conditions (as indexed by use) for songbirds, including several species that are classified as declining. Population losses of those species may be due to otherwise limited availability of early successional habitat within these systems. Introduction Use of agronomic crops (food plots) to supplement naturally occurring Odocoileus virginianus (Zimmerman) (White-tailed Deer; hereafter Deer) forage is becoming increasingly popular in the eastern US (Adams et al. 2009). The benefits of properly planted and managed food plots for Deer have been well documented (Bonner and Fulbright 1999, Edwards et al. 2004, Smith et al. 2007); however, little is known about their impacts on nongame species such as songbirds and small mammals. In forested landscapes of the southern Appalachians of Georgia, Parker et al. (1992) detected 55 bird species and 17 mammal species associated with 2 managed openings, and reported greater avian abundance and diversity in association with Trifolium spp. (perennial clover) food plots than in the adjacent forest. In the Southern Appalachians, Menzel et al. (1999) reported that capture rates of some small-mammal species, such as Sorex cinereus Kerr (Masked Shrew) and Clethrionomys gapperi (Vigors) (Southern Red-backed Vole), were greater along the edge between Schedonorus spp. (fescue)-planted openings and adjacent forest. Donalty et al. (2003) studied plots established for Colinus virginianus (L.) (Northern 1Georgia Department of Natural Resources, Wildlife Resources Division, One Conservation Way, Brunswick, GA 31520. 2Warnell School of Forestry and Natural Resources, University of Georgia, 180 East Green Street, Athens, GA 30602. 3School of Forestry and Wildlife Sciences, Auburn University, 602 Duncan Drive, Auburn, AL 36849. *Corresponding author - wdg0010@auburn.edu. Manuscript Editor: J. Michael Meyers Southeastern Naturalist 163 W.E. Ricks, R.J. Cooper, W.D. Gulsby, and K.V. Miller 2016 Vol. 15, No. 1 Bobwhite) and Deer in Texas and found that rodents and lagomorphs consumed 56% of the total biomass removed from the plots. A few studies have also investigated nesting success of songbirds in wildlife openings and along field–forest edges. For example, both King et al. (2009) and Chandler et al. (2009) found that such wildlife openings were beneficial to shrubscrub nesting songbirds in New England. Gates and Gysel (1978) similarly reported that field–forest edges provided nesting habitat for songbirds, but cautioned that this behavior could negatively impact their survival by concentrating songbirds in small areas, thereby creating ecological traps. Although total land-area dedicated annually to wildlife-food plots is unknown, in 2007 more than 35,000 ha were enrolled in the Wildlife Food Plot (CP12) program within the Conservation Reserve Program alone (Barbarika 2007). Total acreage in food plots planted annually across the eastern US is likely significantly greater because >$700 million are spent nationwide by sportsmen each year for plantings associated with hunting (USFWS 2012). Large-scale use of this management technique and limited data availability suggest that additional research on impacts of these plantings on nongame species is prudent. Herein we report on a study of potential impacts of Deer food plots on breeding songbirds in the northern and southern Appalachians of the eastern US. We hypothesized that songbirds would preferentially use food plots and their edges because of low availability of edge and early-successional habitat types in forested Appalachian systems. Study Sites We selected 20 sites in the northern Appalachians of New York and Pennsylvania and 20 sites in the southern Appalachians of Georgia and Tennessee. All sites consisted of food plots planted in clover, although some food plots also contained forage greens, such as Cichorium sp. (chicory). Food plots ranged from 0.12 ha to 2.99 ha in area. Our northern study sites were located on private and public properties in Potter, Cameron, Indiana, Armstrong, and Westmoreland counties in Pennsylvania and in Cattaraugus, Allegany, and Steuben counties of New York (Fig. 1). All food plots were located within landscapes of extensive, continuous forests where elevations ranged from 411 m to 796 m. All plots contained well-established clover stands during the avian breeding season and were surrounded by mature hardwood forests 50–100 years of age. These forests consisted predominantly of Acer rubrum L. (Red Maple), Quercus prinus L. (Chestnut Oak), Q. rubra L. (Northern Red Oak), Betula lenta L. (Black Birch), Prunus serotina Ehrh. (Black Cherry), Q. alba L. (White Oak), Pinus strobus L. (White Pine), Tsuga canadensis (L.) (Eastern Hemlock), Acer saccharum Marsh. (Sugar Maple), and Fagus grandifolia Ehrh. (American Beech). The understory primarily consisted of Red Maple, Northern Red Oak, Sugar Maple, and other hardwood saplings. Our southern study sites were located on both private and public properties in White, Lumpkin, Gilmer, and Whitfield counties in Georgia and in McMinn and Marion counties in Tennessee (Fig. 1). Elevation of these sites ranged from Southeastern Naturalist W.E. Ricks, R.J. Cooper, W.D. Gulsby, and K.V. Miller 2016 Vol. 15, No. 1 164 200 m to 862 m. As with the northern sites, all plots were surrounded by continuous mature hardwood forests from 50–100 years of age. These forests consisted of Chestnut Oak, Red Maple, Q. falcata Michx. (Southern Red Oak), P. virginiana L. (Virginia Pine), Liriodendron tulipifera L. (Tulip Poplar), Nyssa sylvatica Marshall (Black Gum), Northern Red oak, White Oak, Black Cherry, White Pine, Eastern Hemlock, and American Beech. Their understories mainly consisted of oak saplings, Vaccinium spp. (blueberries), and Vitis rotundifolia Michx. (Muscadine), as well as Kalmia latifolia L. (Mountain Laurel) and hardwood saplings of various other species. Methods We performed breeding-bird surveys during May and early June of 2008 and 2009 on southern sites. We conducted 5-minute fixed-radius (25 m) point-counts at 1 point in the center of each food plot, 2 points along the plot edge, and 2 points 125 m into adjacent forests. We located the first edge and forest points by selecting a random azimuth. We used a second azimuth, 180° opposite the first, to determine the second edge and forest points. We conducted 4 surveys per plot each field season, and all surveys occurred from 30 min after sunrise to 1100 hr. We did not Figure 1. Location of southern and northern Appalachian counties containing Trifolium spp. (perennial clover) food plots where we monitored avian species richness and abundance using pointcount surveys during May–July 2008 and 2009. All food plots were located within landscapes of extensive, continuous hardwood forests. Southeastern Naturalist 165 W.E. Ricks, R.J. Cooper, W.D. Gulsby, and K.V. Miller 2016 Vol. 15, No. 1 conduct surveys during periods of inclement weather (e.g., strong wind or heavy rain). We recorded all point locations with a GPS for precise replication during subsequent surveys. W.E. Ricks conducted all surveys. We noted all visual and audible detections of birds to the species level. We also conducted bird surveys in winter from January to early March 2009 following the same protocol on a subset of 10 southern plots. We repeated winter surveys 10 times at each site over the course of the season. We conducted breeding-bird surveys on northern sites during June and early July of 2008 and 2009 following the same protocol as for southern sites except that we conducted only 2 surveys in 2008. Although multiple observers were employed in 2008, the same observer conducted surveys each time in a given food plot. We used the guidelines of Lindenmayer et al. (2009) to limit the magnitude of any observer effects on results from 2008. During 2009, all surveys were conducted by a single observer. During the spring of 2008, we measured vegetation at each survey point to characterize sites. At four 10 x 10 m quadrants surrounding each point, we recorded the number of woody stems 0.5–7 m tall (i.e., small woody stems), those >7 m tall (i.e., large woody stems), and percent groundcover in each of the following categories: bare ground, graminoids, forbs, and woody plants according to Ellenberg and Mueller-Dombois (1974). We also measured basal area where appropriate. We used ArcMap 9.2 (Environmental Systems Research Institute, Inc., Redlands, CA) to determine food-plot size, perimeter, and perimeter/area ratio. We compared indices of avian species richness and relative abundance (number of individuals detected per point) among treatments via analysis of variance tests and separated means via Tukey HSD tests with α = 0.05. We blocked by site and analyzed data from northern sites, southern sites, and winter separately. At each site, we averaged the 2 edge point-counts and the 2 forest point-counts into single edge and forest counts, respectively. We also compared abundance and species richness of moderate to severely declining (hereafter, declining) species across treatments. We defined declining species as those categorized by Partners in Flight as experiencing a ≥15% or decrease in the northern or southern Appalachian region over the last 30 years (Rocky Mountain Bird Observatory 2005). We divided the total number of declining songbird species by the overall number of songbird species detected at each site, by treatment, to find percent richness of declining species. We also identified species that we recorded in only 1 treatment class (i.e., plot, edge, or adjacent forest). Results Vegetative characteristics varied little within treatment classes among sites, except small woody-stem density, which was greater on northern sites for both edge and forest treatments (Table 1). Food plots were primarily composed of graminoidand forb-cover types, and the understory along edges and in the forest primarily consisted of leaf litter, with some woody cover. Southeastern Naturalist W.E. Ricks, R.J. Cooper, W.D. Gulsby, and K.V. Miller 2016 Vol. 15, No. 1 166 During our study, we recorded 1735 individual songbirds representing 79 species on northern sites (Table 2). The most commonly detected species included Vireo olivaceus (Red-eyed Vireo), Pipilo erythrophthalmus (Eastern Towhee), and Turdus migratorius (American Robin). We found no differences in avian abundance (F2,19 = 0.29, P = 0.75) or species richness (F2,19=1.11, P = 0.34) among treatments (Table 3). Twenty-nine of the species we detected on northern sites were classified as declining in the Appalachian region (Table 2). For declining species, mean avian abundance was 2.0 and 2.5 times greater for edge and plot treatments, respectively, than for the forest treatment (F2,19 = 9.23, P < 0.01), and mean species richness was 2.0 and 2.3 times greater for edge and plot treatments, respectively, than for the forest treatment (F2,19 = 17.65, P < 0.01) (Table 4). We detected 810 individual songbirds representing 61 species during 2 breeding seasons on southern sites. Passerina cyanea (Indigo Bunting), Red-eyed Vireo, and Cardinalis cardinalis (Northern Cardinal) were the most common species (Table 5). Mean species richness was 1.7 times greater for the edge treatment than for the forest treatment (F2,19 = 18.11, P < 0.01), and mean avian abundance was 2.4 times greater for the edge treatment than for the forest treatment (F2,19 = 25.53, P < 0.01) (Table 3). Twenty-seven of the species detected at southern sites were classified as declining in the Appalachian Region (Table 5). For these species, mean Table 1. Vegetative characteristics of Trifolium spp. (perennial clover) food plots, food-plot edges, and adjacent forests located in the northern (New York and Pennsylvania) and southern (Georgia and Tennessee) Appalachian Mountains in 2008. Small woody stems = 0.5 m to 7 m tall, large woody stems = greater than 7 m in height, and percent groundcover was quantified according to Ellenberg and Mueller-Dombois (1974). Edge Forest Food plot Habitat characteristics n Mean SE Mean SE Mean SE Northern sites Plot size (ha) 20 0.9 0.2 Perimeter/area ratio (m/m2) 20 less than 0.1 less than 0.1 Basal area (m2/ha) 20 23.1 1.9 25.7 1.9 Small woody stems (#/100 m 2) 20 94.0 21.0 191.7 42.9 Large woody stems (#/100 m2) 20 0.9 0.2 0.6 0.1 Bare ground/leaf litter (%) 20 56.6 12.6 69.9 15.6 6.1 1.4 Graminoid cover (%) 20 10.7 2.4 6.5 1.5 35.5 7.9 Forb cover (%) 20 24.4 5.4 13.8 3.1 58.5 13.1 Woody cover (%) 20 7.2 1.6 9.8 2.2 0.0 Southern sites Plot size (ha) 20 0.7 0.2 Perimeter/area ratio (m/m2) 20 less than 0.1 less than 0.1 Basal area (m2/ha) 20 26.9 1.7 28.4 2.0 Small woody stems (#/100 m 2) 20 14.7 3.3 9.9 2.2 Large woody stems (#/100 m2) 20 0.7 0.1 0.9 0.2 Bare ground/leaf litter (%) 20 66.3 14.8 71.9 16.1 3.0 0.7 Graminoid cover (%) 20 4.2 0.9 2.6 0.6 31.2 7.0 Forb cover (%) 20 9.4 2.1 10.4 2.3 65.7 14.7 Woody cover (%) 20 20.3 4.5 14.0 3.1 0.2 less than 0.1 Southeastern Naturalist 167 W.E. Ricks, R.J. Cooper, W.D. Gulsby, and K.V. Miller 2016 Vol. 15, No. 1 Table 2. Number of detections per species, by treatment, during the breeding seasons of 2008 and 2009 within Trifolium spp. (perennial clover) food plots, at their edges, and in the adjacent forest in the northern (New York and Pennsylvania) Appalachian Mountains. Declining species = species that have experienced ≥15% decline in the Appalachian region over the last 30 y (Rocky Mountain Bird Observatory 2005). [Continued on following page.] Treatment Scientific name Common name Edge Food plot Forest Total Empidonax alnorum Brewster Alder Flycatcher 1 2 3 Corvus brachyrhynchos Brehm American Crow 4 2 5 11 Setophaga ruticilla (L.) American Redstart 26 3 22 51 Turdus migratorius L. American Robin 42 30 29 101 Icterus galbula (L.) Baltimore Oriole 2 2 4 Dendroica fusca (Müller) Blackburnian Warbler 4 2 8 14 Poecile atricapillus L. Black-capped Chickadee 20 19 28 67 Dendroica caerulescens (Gmelin) Black-throated Blue Warbler 2 8 10 Dendroica virens (Gmelin) Black-throated Green Warbler 7 6 24 37 Vireo solitarius (Wilson) Blue-headed Vireo 7 2 5 14 Dolichonyx oryzivorus (L.) Bobolink 1 1 2 Certhia americana Bonaparte Brown Creeper 4 4 Wilsonia Canadensis (L.) Canada Warbler 1 1 Thryothorus ludovicianus (Latham) Carolina Wren 1 1 Dendroica pensylvanica (L.) Chestnut-sided Warbler 6 6 12 24 Chaetura pelagica (L.) Chimney Swift 1 3 4 Geothlypis trichas (L.) Common Yellowthroat 24 7 25 56 Junco hyemalis (L.) Dark-eyed Junco 26 18 14 58 Sialia sialis (L.) Eastern Bluebird 6 6 12 Sayornis phoebe (Latham) Eastern Phoebe 1 2 5 8 Dumetella carolinensis (L.) Gray Catbird 15 7 5 27 Picoides villosus (L.) Hairy Woodpecker 9 2 10 21 Catharus guttatus (Pallas) Hermit Thrush 2 4 6 Wilsonia citrina (Boddaert) Hooded Warbler 23 5 21 49 Carpodacus mexicanus (Müller) House Finch 1 1 Troglodytes aedon Vieillot House Wren 1 1 Dendroica magnolia (Wilson) Magnolia Warbler 2 6 8 Zenaida macroura (L.) Mourning Dove 8 6 6 20 Oporornis philadelphia (Wilson) Mourning Warbler 2 2 Cardinalis cardinalis (L.) Northern Cardinal 5 5 9 19 Seiurus aurocapilla (L.) Ovenbird 15 5 28 48 Dryocopus pileatus (L.) Pileated Woodpecker 3 3 Spinus pinus (Wilson) Pine Siskin 2 2 Dendroica pinus (L.) Pine Warbler 6 5 11 Carpodacus purpureas (Gmelin) Purple Finch 1 1 Melanerpes carolinus (L.) Red-bellied Woodpecker 2 3 5 Vireo olivaceus (L.) Red-eyed Vireo 79 26 102 207 Pheucticus ludovicianus (L.) Rose-breasted Grosbeak 9 1 7 17 Archilochus colubris (L.) Ruby-throated Hummingbird 1 1 2 4 Piranga olivacea (Gmelin) Scarlet Tanager 28 10 26 64 Catharus ustulatus (Nuttall) Swainson’s Thrush 2 2 Melospiza georgiana (Latham) Swamp Sparrow 1 1 Tachycineta bicolor (Vieillot) Tree Swallow 1 1 Catharus fuscescens (Stephens) Veery 7 1 15 23 Sitta carolinensis Latham White-breasted Nuthatch 15 1 6 22 Vireo griseus (Boddaert) White-eyed Vireo 1 2 3 Troglodytes troglodytes (L.) Winter Wren 1 1 Southeastern Naturalist W.E. Ricks, R.J. Cooper, W.D. Gulsby, and K.V. Miller 2016 Vol. 15, No. 1 168 Table 2, continued. Treatment Scientific name Common name Edge Food plot Forest Total Sphyrapicus varius (L.) Yellow-bellied Sapsucker 21 12 23 56 Dendroica coronata (L.) Yellow-rumped Warbler 1 1 Dendroica dominica (L.) Yellow-throated Warbler 1 1 Declining species Spinus tristis (L.) American Goldfinch 2 18 1 21 Mniotilta varia (L.) Black-and-white Warbler 13 7 10 30 Passerina caerulea (L.) Blue Grosbeak 1 1 Cyanocitta cristata (L.) Blue Jay 8 8 16 32 Toxostoma rufum (L.) Brown Thrasher 1 1 Molothrus ater (Boddaert) Brown-headed Cowbird 23 19 8 50 Spizella passerina (Bechstein) Chipping Sparrow 34 56 2 92 Quiscalus quiscula (L.) Common Grackle 3 3 Picoides pubescens (L.) Downy Woodpecker 2 3 5 Pipilo erythrophthalmus (L.) Eastern Towhee 48 12 45 105 Contopus virens (L.) Eastern Wood-Pewee 5 7 12 Sturnus vulgaris L. European Starling 19 19 Spizella pusilla (Wilson) Field Sparrow 7 7 1 15 Myiarchus crinitus (L.) Great Crested Flycatcher 5 3 5 13 Passerina cyanea (L.) Indigo Bunting 38 25 24 87 Oporornis formosus (Wilson) Kentucky Warbler 3 2 5 10 Empidonax minimus (Baird & Baird) Least Flycatcher 12 1 11 24 Colaptes auratus (L.) Northern Flicker 4 3 3 10 Dendroica discolor (Vieillot) Prairie Warbler 1 1 2 Loxia curvirostra L. Red Crossbill 1 1 Agelaius phoeniceus (L.) Red-winged Blackbird 3 7 10 Bonasa umbellus (L.) Ruffed Grouse 15 15 Passerculus sandwichensis (Gmelin) Savannah Sparrow 1 2 3 Melospiza melodia (Wilson) Song Sparrow 18 11 1 30 Pooecetes gramineus (Gmelin) Vesper Sparrow 2 1 3 Hylocichla mustelina (Gmelin) Wood Thrush 10 3 7 20 Coccyzus americanus (L.) Yellow-billed Cuckoo 1 1 Icteria virens (L.) Yellow-breasted Chat 2 2 Vireo flavifrons Vieillot Yellow-throated Vireo 4 5 9 Table 3. Mean species abundance and richness of songbirds observed during the breeding seasons of 2008 and 2009, and the winter of 2009 (southern sites only), within Trifolium spp. (perennial clover) food plots, at their edges, and in the adjacent forest in the northern (New York and Pennsylvania) and southern (Georgia and Tennessee) Appalachian Mountains. Means with different letters are significantly different (P < 0.05). Edge Forest Food plot Survey Measure n Mean SE Mean SE Mean SE Breeding bird survey Northern sites Abundance index 20 17.7A 1.4 16.4A 1.4 17.7A 2.1 Species richness 20 8.2A 0.5 7.5A 0.4 8.8A 1.0 Southern sites Abundance index 20 13.9A 1.6 5.7B 0.7 5.6B 1.1 Species richness 20 5.5A 0.4 3.2 B 0.3 2.5B 0.6 Winter bird survey Abundance index 10 8.3A 2.4 3.6A 1.2 2.8A 1.5 Species richness 10 2.5A 0.3 1.3 A B 0.2 0.6B 0.2 Southeastern Naturalist 169 W.E. Ricks, R.J. Cooper, W.D. Gulsby, and K.V. Miller 2016 Vol. 15, No. 1 Table 4. Mean species abundance and richness of declining songbird species observed during the breeding seasons of 2008 and 2009, and the winter of 2009 (southern sites only), within Trifolium spp. (perennial clover) food plots, at their edges, and in the adjacent forest in the northern (New York and Pennsylvania) and southern (Georgia and Tennessee) Appalachian Mountains. Declining species = species that have experienced ≥15% decline in the Appalachian region over the last 30 y (Rocky Mountain Bird Observatory 2005). Means with different letters are significantly different (P < 0.05). Edge Forest Food plot Survey Measure n Mean SE Mean SE Mean SE Breeding bird survey Northern sites Abundance index 20 5.3A 0.4 2.7B 0.4 6.7A 0.6 Species richness 20 2.3A 0.1 1.2B 0.1 2.7A 0.2 Southern sites Abundance index 20 5.3A 0.6 1.7B 0.2 3.3AB 0.6 Species richness 20 2.1A 0.2 1.0B 0.1 1.2B 0.2 Winter bird survey Abundance index 10 0.3A 0.1 0.1A 0.1 0.5A 0.3 Species richness 10 0.2A 0.1 0.1A 0.1 0.3A 0.2 Table 5. Number of detections per species, by treatment, during the breeding seasons of 2008 and 2009 within Trifolium spp. (perennial clover) food plots, at their edges, and in the adjacent forest in the southern (Georgia and Tennessee) Appalachian Mountains. Declining species = species that have experienced ≥15% decline in the Appalachian region over the last 30 y (Rocky Mountain Bird Observatory 2005). [Continued on following page.] Treatments Scientific name Common name Edge Plot Forest Total Corvus brachyrhyncos American Crow 4 1 2 7 Setophaga ruticilla American Redstart 3 3 Turdus migratorius American Robin 1 1 Hirundo rustica L. Barn Swallow 2 2 Dendroica striata (Forster) Blackpoll Warbler 2 2 Dendroica caerulescens Black-throated Blue Warbler 1 1 Dendroica virens Black-throated Green Warbler 20 9 29 Vireo solitarius Blue-headed Vireo 2 2 4 Poecile carolinensis Audubon Carolina Chickadee 15 10 25 Thryothorus ludovicianus Carolina Wren 11 2 6 19 Dendroica pensylvanica Chestnut-sided Warbler 1 1 Chaetura pelagica Chimney Swift 1 2 3 Geothlypis trichas Common Yellowthroat 6 3 2 11 Sialia sialis Eastern Bluebird 4 1 5 Sayornis phoebe Eastern Phoebe 2 2 Dumetella carolinensis Gray Catbird 5 2 7 Picoides villosus Hairy Woodpecker 4 4 Wilsonia citrina Hooded Warbler 16 1 11 28 Zenaida macroura Mourning Dove 1 1 1 3 Cardinalis cardinalis Northern Cardinal 39 2 16 57 Parula americana (L.) Northern Parula 5 1 6 Seiurus aurocapilla Ovenbird 13 15 28 Dryocopus pileatus Pileated Woodpecker 1 2 3 Dendroica pinus Pine Warbler 8 3 4 15 Melanerpes carolinus Red-bellied Woodpecker 1 1 Vireo olivaceus Red-eyed Vireo 85 6 49 140 Southeastern Naturalist W.E. Ricks, R.J. Cooper, W.D. Gulsby, and K.V. Miller 2016 Vol. 15, No. 1 170 abundance was 3.1 times greater for the edge treatment than for the forest treatment (F2,19 = 10.55, P < 0.01), and mean species richness was 2.1 times greater for the edge treatment than for the forest treatment (F2,19 = 9.13, P = 0.0006) (Table 4). During winter surveys on southern sites, we detected 154 individual songbirds representing 26 species. The most common species were Junco hyemalis (Darkeyed Junco), Baeolophus bicolor (L.) (Tufted Titmouse), and Poecile carolinensis (Audubon) (Carolina Chickadee). During winter, we found no difference in avian abundance among treatments (P = 0.26, F2,9 = 1.42), but mean species richness was 1.9 times greater along edges than in plots (P = 0.0031, F2, 9 = 8.09) (Table 3). We detected 6 species classified as declining in the Appalachian Region. We found no Table 5, continued. Treatments Scientific name Common name Edge Plot Forest Total Archilochus colubris Ruby-throated Hummingbird 1 1 2 Piranga olivacea Scarlet Tanager 7 4 11 Catharus ustulatus Swainson’s Thrush 1 1 Vireo griseus (Boddaert) White-eyed Vireo 11 2 1 14 Zonotrichia albicollis (Gmelin) White-throated Sparrow 2 2 Sphyrapicus varius Yellow-bellied Sapsucker 1 1 Dendroica coronata Yellow-rumped Warbler 1 1 Dendroica dominica Yellow-throated Warbler 11 2 13 Declining species Empidonax virescens (Vieillot) Acadian Flycatcher 11 7 18 Spinus tristis American Goldfinch 1 2 3 Mniotilta varia Black-and-white Warbler 11 8 19 Passerina caerulea Blue Grosbeak 3 2 5 Cyanocitta cristata Blue Jay 5 1 6 Polioptila caerulea (L.) Blue-gray Gnatcatcher 22 4 12 38 Toxostoma rufum Brown Thrasher 2 3 5 Molothrus ater Brown-headed Cowbird 5 1 4 10 Spizella passerina Chipping Sparrow 1 1 Caprimulgus carolinensis (Gmelin) Chuck-will’s-widow 1 1 Picoides pubescens Downy Woodpecker 1 1 Pipilo erythrophtalmus Eastern Towhee 7 5 12 Contopus virens Eastern Wood Pewee 1 1 2 Spizella pusilla Field Sparrow 4 2 1 7 Myiarchus crinitus Great-crested Flycatcher 1 1 Passerina cyanea Indigo Bunting 109 53 12 174 Oporornis formosus Kentucky Warbler 3 1 4 Empidonax minimus Least Flycatcher 2 2 Seiurus motacilla (Vieillot) Louisiana Waterthrush 1 4 5 Dendroica discolor Prairie Warbler 3 2 3 8 Protonotaria citrea (Boddaert) Prothonotary Warbler 2 2 Loxia curvirostra Red Crossbill 1 1 Melospiza melodia Song Sparrow 2 2 Piranga rubra (L.) Summer Tanager 6 2 8 Hylocichla mustelina Wood Thrush 3 3 Icteria virens Yellow-breasted Chat 12 3 3 18 Vireo flavifrons Yellow-throated Vireo 2 2 Southeastern Naturalist 171 W.E. Ricks, R.J. Cooper, W.D. Gulsby, and K.V. Miller 2016 Vol. 15, No. 1 difference in abundance (F2,9 = 0.88, P = 0.43) or richness (P = 0.54, F2,9 = 0.64) among treatments for these species (Table 4). Overall, mean richness of declining species was greatest within food plots and least in adjacent forests for both northern and southern sites (Table 6). During breeding-bird surveys on southern sites, we observed 14 unique species at edge, 7 at forest, and 2 at food-plot points (Table 5). On northern sites, we observed 9 unique species at edge, 10 at forest, and 4 at food-plot points (Table 2). During winter surveys in southern sites, we documented 5 unique species at edge, 1 at forest, and 1 at food-plot points. We observed very few Molothrus ater (Brown-headed Cowbird) in food plots (n = 20; 0.8% of total observations), at edge points (n = 28; 1.1% of total observations), or in the adjacent forest (n = 12; 0.5% of total observations) during all field seasons (Tables 2, 5). Discussion Given that species richness and abundance are correlated for breeding birds due to territoriality (Tramer 1969), one would expect these variables to respond similarly to each treatment during the breeding-bird surveys. Our results for the southern sites confirmed this assumption because both avian species richness and abundance were greater along edges there during the breeding season. In contrast, neither richness nor abundance differed among treatments on northern sites, a finding which may be explained by differences in densities of small woody stems between regions. Relatively high availability of this habitat feature in both edges and forests on northern sites increased vertical-structure complexity and, thus, may have resulted in functional similarity between these treatments for scrub-shrub species. For example, forest and edge detections of Eastern Towhees and Indigo Buntings, which breed in scrub-shrub habitats (Schlossberg and King 2007), were similar on northern sites, and they were among the 5 most commonly detected species in the region. In contrast, these and other mixed-habitat species are typically concentrated along edges in areas where low-woody structure is lacking in both the surrounding field and forest (Gates and Gysel 1978), as at our southern sites where Table 6. Mean percent richness of declining songbird species compared to the overall species richness of declining songbird species observed during the breeding seasons of 2008 and 2009 within Trifolium spp. (perennial clover) food plots, at their edges, and in the adjacent forest in the northern (New York and Pennsylvania) and southern (Georgia and Tennessee) Appalachian Mountains, along with similar data from winter surveys conducted only in the southern Appalachians. Declining species = species that have experienced ≥15% decline in the Appalachian region over the last 30 y (Rocky Mountain Bird Observatory 2005). Edge Forest Food plot Survey Measure n Mean SE Mean SE Mean SE Breeding bird survey Northern sites Percent richness 20 28% 1.20 16% 0.70 36% 1.60 Southern sites Percent richness 20 36% 1.70 29% 1.30 45% 1.80 Winter bird survey Percent richness 10 6% 0.06 4% 0.04 50% 0.30 Southeastern Naturalist W.E. Ricks, R.J. Cooper, W.D. Gulsby, and K.V. Miller 2016 Vol. 15, No. 1 172 woody stem densities were relatively low and we detected Indigo Buntings, for example, 9 times more frequently at edges than in the forest. We documented a number of species that occurred only in food plots or at their edges. In addition, mean avian abundance, richness, and mean percent richness of declining species were greater within food plots and/or at their edges than in the adjacent forest. Thus, food plots and their associated edges appear to provide attractive habitat for a variety of avian species during the breeding season, including many classified as in decline. Although we did not measure it, post-breeding avian richness and abundance may have been even greater in food plots and their associated second-growth edges. During this period, even forestdependent species utilize early-successional habitats (Pagen et al. 2000) because they often contain greater availability of forage and shelter—important features for vulnerable young and molting adult birds (Hollifield and Dimmick 1995, Vitz and Rodewald 2007). Presence of breeding songbirds is not a complete measure of habitat quality. Avian species such as Brown-headed Cowbirds, Corvus brachyrhynchos (American Crow), and Cyanocitta cristata (Blue Jay), as well as mammalian and reptilian nest predators are capable of negatively affecting nest success (Gates and Gysel 1978). Although we rarely detected these avian species during our surveys, we did not measure nest success and cannot make inferences regarding this factor. In the only other study that assessed songbird use of clover food-plots in forested habitats, Parker et al. (1992) detected 55 bird species associated with managed openings in the southern Appalachians of Georgia. Similar to our results, they concluded that food plots and their associated edges were beneficial for many avian species. However, we caution against extrapolation of our results to other settings because we only examined food plots planted in perennial clovers that were located within extensive continuous forests. We also recommend caution in comparing our results to those of others because our surveys began 30 min after sunrise—later than the 15-min post-sunrise timing suggested by Ralph et al. (1993). 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