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Habitat Selection of Wild Pigs and Northern Bobwhites in Shrub-dominated Rangeland
Susan M. Cooper and Shane S. Sieckenius

Southeastern Naturalist, Volume 15, Issue 3 (2016): 382–393

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Southeastern Naturalist S.M. Cooper and S.S. Sieckenius 2016 Vol. 15, No. 3 382 2016 SOUTHEASTERN NATURALIST 15(3):382–393 Habitat Selection of Wild Pigs and Northern Bobwhites in Shrub-dominated Rangeland Susan M. Cooper1,* and Shane S. Sieckenius1 Abstract - Sus scrofa L. (Wild Pig) are known to eat the eggs of ground-nesting birds, but it is unknown to what extent they have an impact on populations of Colinus virginianus L. (Northern Bobwhite). We combined data from 2 prior studies conducted on a large ranch in South Texas to assess comparative habit use and selection by Wild Pigs and Bobwhites. Both species were distributed throughout the ranch, but their preferred habitats were very different. Bobwhites favored upland habitats, particularly areas with deep, sandy soils, while Wild Pigs favored low-lying habitats with clay soils. We conclude that depredation of Bobwhite nests by these invasive mammals may be restricted by the thermoregulatory requirement for Wild Pigs to stay near riparian areas. The extent of this effect will depend on the availability and spatial arrangement of water and riparian areas on the landscape. Introduction Colinus virginianus L. (Northern Bobwhite, hereafter Bobwhite) are a valuable hunting and recreational wildlife resource that provides income to rural economies (Burger et al. 1999, Conner 2007). Consequently, the long-term population decline of this species throughout most of its range (Brennan 1991, Hernández et al. 2013) is of concern to many sportsmen, conservationists, and landowners. In Texas, the rate of decline of Bobwhite populations averages 2.78% a year (Sauer et al. 2014). Within the South Texas Plains ecoregion, numbers of Bobwhites have been consistently low since the mid-1990s and show little sign of recovery despite much effort in managing land for this species (TPWD 2014). In contrast, Sus scrofa L. (Wild Pig) are expanding in range and abundance in the US (Gipson et al. 1998). In Texas, the Wild Pig population, derived from feral Sus scrofa domesticus) Erxleben (Domestic Pig) often hybridized with Eurasian Wild Boar; Wilson and Reeder 2005), was estimated to be around 1 million animals in the 1990s (Taylor 1991, 1993). However, a recent synthesis of current literature and harvest records by Timmons et al. (2012) estimated that there are now 2.6 million (range = 1.8–3.4) Wild Pigs in Texas. Furthermore, based on their high fecundity, simulation modeling predicts the potential for even larger populations in the future (Mellish et al. 2014). There is concern that the ever-growing population of Wild Pigs may hinder recovery of Bobwhite populations. Wild Pigs readily consumed eggs in nest predation studies that used artificial nests baited with Gallus gallus domesticus L. (Domestic Chicken) or hatchery-produced Bobwhite eggs (Cooper 2006, Tolleson et al. 1993), and they have been documented depredating nests of Bobwhites (Rollins 1Texas A&M AgriLife Research, 1619 Garner Field Road, Uvalde, TX 78801. *Corresponding author - Manuscript Editor: John C. Kilgo Southeastern Naturalist 383 S.M. Cooper and S.S. Sieckenius 2016 Vol. 15, No. 3 and Carroll 2001) and Meleagris gallopavo L. (Eastern Wild Turkey; Dreibelis et al. 2008). It is possible that nest predation by Wild Pigs could have a negative effect on local population-recruitment of Bobwhites, particularly if there is considerable overlap in their habitat use during Bobwhite nesting season. Depredation by non-native Wild Pigs has been implicated in declines of several populations of ground-nesting birds on islands (Donlan et al. 2007, Miller and Mullette 1985) and in Europe (Nyenhuis 1991). In Texas, Petty et al. (2007) found that control of Wild Pig populations has been effective in aiding restoration of Eastern Wild Turkey. Yet to date, quantitative evidence of the impact of Wild Pig depredation on Bobwhite populations is lacking (Rollins et al. 2007, West et al. 2009). In this study, we synthesized information from 2 independent studies that we had previously undertaken. One study assessed the distribution and movements of GPScollared Wild Pigs on a large ranch in Texas (Cooper et al. 2010) in order to model potential disease-transmission between Wild Pigs and Bos taurus L. (Domestic Cattle). The other study is an ongoing, long-term monitoring program on Bobwhite populations on the same ranch and other member ranches of the South Texas Covey Connection (Cooper et al. 2009). We combined data from these 2 studies to identify habitats within South Texas rangeland in which Wild Pigs are most likely to overlap in distribution with nesting Bobwhites. Through depredation of nests, mammals are the main predators of quail during the breeding season (Rollins and Carroll 2001); thus, our hypothesis was that knowledge of the comparative distribution of Wild Pigs and Bobwhite during Bobwhite breeding season should be important for assessing the negative effects of Wild Pigs on Bobwhite populations. Field-Site Description The main study area was a 30,521-ha low-fenced ranch in Zavala County, TX, within the South Texas Plains ecoregion. Supplemental data on Bobwhite populations, but not Wild Pigs, over the same time period was also available from 3 additional ranches in Zavala and Frio counties, which together covered 10,950 ha of habitat similar to that on the main study-ranch. The regional climate is subtropical and semi-arid with hot, dry summers (mean temperature = 37 °C in July) and mild winters (mean temperature = 4 °C in January) (Griffith et al. 2007). The 100-y average for annual precipitation is 555 mm (NOAA 2014), but there is great annual variability. During the 11 y of Bobwhite population surveys from 2004 to 2014, annual precipitation measured on-site averaged 523 mm, but ranged from 293 to 870 mm/y. During the 2 y of the Wild Pig study, from 2004 to 2006, rainfall was slightly above average at 635 mm/y. The South Texas Plains ecoregion is characterized by gently rolling topography vegetated by a diverse, thorn-shrub community (Griffith et al. 2007). Soil types on the study ranch were 14% clay, 66% clay-loam, 16% sandy-loam, and 3% deep, sandy soil (USDA-NRCS 2012). The 3 additional ranches lacked deep sandy soils. Soil types were 5% clay, 34% clay-loam, 12 % loamy-sand, 33% sandy-loam, and 15% gravelly-loam. The most characteristic woody plant on clay and clay-loam soils was Prosopis glandulosa Torr. (Honey Mesquite), growing in combination Southeastern Naturalist S.M. Cooper and S.S. Sieckenius 2016 Vol. 15, No. 3 384 with Opuntia engelmannii Salm-Dyck ex Engelm. (Pricklypear Cactus) and a diverse array of drought-tolerant shrubs, such as Guaiacum angustifolium Engelm. (Guayacan), Zizyphus obtusifolia (Hook. ex Torr. & A. Gray) Gray (Lotebush), Castela erecta Turpin (All-thorn), and Celtis pallida Torr. (Spiny Hackberry). Mesquite was less abundant on the sandy-loam soils, which were densely vegetated with shrubs of Vachellia rigidula (Benth.) Seigler & Ebinger (Blackbrush Acacia), Senegalia berlandieri Brittom & Rose (Guajillo), and Leucophyllum frutescens (Berl.) I.M. Johnst (Cenizo). Some of the shrubland had been cleared in alternating strips to increase grazing for cattle and wildlife. Native grasses were abundant on the ranch but the introduced pasture grass Cenchrus ciliaris L. (Buffelgrass) was dense on the clay-loam soils. The area of sandy soil on the northern section of the ranch was characterized by more-open grassland with Mesquite, Pricklypear, and mottes (groves) of Sideroxylon lanuginosum Michx. (Spiny Bumelia). Grasses on the sandy soils were all native species characterized by the presence of Schizachyrium scoparium (Michx.) Nash (Little Bluestem) (Correll and Johnson 1970, ITIS 2015). Many ephemeral drainages leading into the Turkey Creek system, parts of which usually held water year-round, were present on the landscape. Riparian areas were predominantly narrow bands of dense shrubs and Mesquite trees along the drainages. Riparian areas around permanent water bodies contained taller trees including Quercus virginiana Mill. (Live Oak) and Carya illinoinensis (Wangenh.) K. Koch. (Pecan). All pastures contained earthen stock-ponds to provide water for Cattle. There were 5 cultivated and irrigated fields of 71–88 ha planted with Sorghum x almum Parodi (Columbus Grass) and 14 scattered food-plots of 0.81–2.02 ha (2–5 ac) planted with Avena sativa L. (Oats) for wildlife. The ranch was used for game production and cattle grazing. Hunted game species included Odocoileus virginianus Zimmermann (White-tailed Deer), Wild Pigs, Pecari tajacu L. (Javelina), Rio Grande Wild Turkey, Bobwhite, and Callipepla squamata Vigors (Scaled Quail). We did not measure Wild Pig density on the study site, but Timmons et al. (2012) estimated that Wild Pigs in Texas occur at a density of 3.4–6.3 /km2. Methods Assessment of Bobwhite abundance and distribution From mid-April through May 2004−2014, we conducted surveys of Bobwhites by recording the abundance of calling roosters at 10 call-stations spaced equidistantly along a 16-km route on each ranch. Following standard procedures for spring call-counts (Guthery 1986, Hansen and Guthery 2001, Rollins et al. 2005), we monitored each station for 5 min on 3 non-consecutive mornings. At each site, we noted the number of Bobwhites calling and we recorded their locations by compass direction and estimated distance of each bird from the observer. The suggested distance over which Bobwhite calls are audible is ~600 m (Rollins et al. 2005); however, during this study, we found that a distance of 400 m (survey area 50 ha) was a more appropriate estimate because our ability to hear Bobwhites in this shrubby country was reduced by the background noise-level of birdsong, including numerous Mimus polyglottos L. (Northern Mockingbird) partially imitating Bobwhite calls. Southeastern Naturalist 385 S.M. Cooper and S.S. Sieckenius 2016 Vol. 15, No. 3 We used ArcView 10 (ESRI, Redlands, CA) to plot the 400-m-radius circles around each survey point and Bobwhite locations on digital aerial photography from TNRIS (2014). We overlaid a map of ecological sites derived from the USDA-NRCS web soil-survey (2012) to determine proportions of each ecological site (habitat type) within the survey circles. In this paper, we capitalize ecological site-names to differentiate those names from similarly named soil types. Ecological sites are derived from a combination of soil type and topography that influences the vegetation communities at each site (Table 1); thus, they delineate land units that share similar characteristics over a wide geographic area (USDA-NRCS 2011). We classified an ecological site as selected or avoided if the proportional occurrence of calling Bobwhites differed significantly from the proportion of that ecological site available within the combined counting circles on the ranch. We tested differences between proportional use and availability of ecological sites with the chisquare (χ2) statistic and accepted differences at P < 0.05 (Neu et al. 1974). Preference for individual sites was confirmed by individual chi-square tests with Bonferroni adjustment (Byers et al. 1984, McDonald 2014). Given that home ranges of Bobwhites in the breeding season are only10–15 ha in extent (Haines et al. 2004, Liu et al. 2002), we made the assumption that Bobwhites were likely to nest close enough to their calling sites to remain within the same ecological site as the calling rooster. The average number of calling roosters/site is presented with the standard error (SE). We did not describe the distribution of Bobwhites relative to landscape features, such as riparian areas and ranch roads, because standard protocol for Bobwhite survey points places them near access roads and outside riparian zones. Table 1. Proportions of ecological sites within the study ranch in the South Texas Plains ecoregion. A more-detailed description of each ecological site can be found at USDA-NRCS (2011) Ecological Site Information System. Ecological site Soil characteristics % occurrence Upland areas Clay Flat Clay 6.49 Saline Clay Clay, saline 6.78 Clay Loam Clay-loam, on caliche 46.97 Rolling Hardland Clay-loam, on shale, saline 11.27 Loamy Sand Loamy-sand 0.04 Sandy Loam Sandy-loam 5.50 Gray Sandy Loam Sandy-loam 8.56 Shallow Sandy Loam Sandy-loam on sandstone 0.41 Sandy Deep sand 3.15 Shallow Ridge Gravelly-loam, on caliche 0.26 Gravelly Ridge Gravelly-loam 0.30 Lowland and drainages Clayey Bottomland Deep clay 0.67 Claypan Prairie Fine sandy-clay-loam 7.07 Tight Sandy Loam Sandy-loam 1.77 Loamy Bottomland Silty-clay-loam 0.20 Lakebed Clay-loam 0.02 Water Stock ponds 0.54 Southeastern Naturalist S.M. Cooper and S.S. Sieckenius 2016 Vol. 15, No. 3 386 Habitat use and selection by Wild Pigs Information on habitat use and selection by Wild Pigs is based on GPS collar (BlueSky Telemetry® Limited, Aberfeldy, Scotland; and Lotek Wireless Incorporated, Newmarket, ON, Canada) data collected on the main study ranch from July 2004 to August 2006 (Cooper et al. 2010). Collars provided locations of the animals every 15 min at spatial accuracy of ± 5 m (Hulbert and French 2001, Moen et al. 1997). We used data from the 2 spring (March–May) trials and 2 summer (June–August) trials to describe the distribution of 16 Wild Pigs during the Bobwhite breeding season, which lasts from April to September (Hernández and Peterson 2007). We used box traps to catch the Wild Pigs for collaring. We ear-tagged captured Wild Pigs to prevent re-use of previously collared animals, and we were careful not to collar more than 1 animal from each sounder, or family group. Trapping and handling of Wild Pigs followed Animal Use Protocols #2002-380 and #2005-281 approved by Texas A&M University Institutional Animal Care and Use Committee. In addition to ecological sites, we assessed Wild Pig distribution relative to landscape features digitized from digital aerial photography from TNRIS (2014). These features included: (a) creeks and drainages buffered at 50 m to delineate riparian vegetation, (b) water (stock ponds) buffered at 50 m due to fluctuating water levels, (c) cultivated fields which were fenced and therefore not buffered, and (d) ranch roads buffered at 20 m from the center-line. Areas of these landscape features were: riparian = 3096 ha, water = 636 ha, cultivated = 896 ha, and roads = 3218 ha. We classified the remaining 25,033 ha (82%) of rangeland that were not within 1 of these 4 categories as shrubland. Supplemental-feeding sites for deer were fenced to exclude Wild Pigs and Cattle; thus we did not include them in the analysis. We determined use of ecological sites or landscape features by Wild Pigs each season by the proportion of GPS locations falling within each ecological site or feature compared to the proportional extent of that ecological site or feature within the study area. We employed individual chi-square (χ2) tests with Bonferroni adjustment to verify site selection (Byers et al. 1984, McDonald 2014). For Wild Pigs, we designated as available habitat the 25,888 ha of the ranch south of Texas State Highway 57 because none of the home ranges of the collared animals extended across the highway. Results Habitat use and selection by Bobwhites On the study ranch, habitat selection by Bobwhites was dominated by a strong preference for the Sandy ecological site (Table 2) and a corresponding avoidance of the abundant Clay Loam sites (χ2 3 = 24.11, P < 0.001). Occurrence of Clay Flat sites within the survey circles was low, but a trend towards avoidance of this ecological site was evident. Over the 11 years, the mean ± SE number of roosters heard was 5.0 ± 1.0 roosters/50-ha survey circle in Sandy sites, compared to 2.1 ± 0.5 roosters/50 ha in Clay Loam sites, and 1.8 ± 0.4 roosters/50 ha in Clay Flat sites. On the 3 additional ranches, which did not have areas of deep sandy soils but had various loamy soils, no clear preference for any specific ecological sites by Southeastern Naturalist 387 S.M. Cooper and S.S. Sieckenius 2016 Vol. 15, No. 3 Bobwhites was evident (χ2 7 = 9.80, P > 0.05; χ2 5 = 2.02, P > 0.05; and χ2 7 = 6.44, P > 0.05), although there was a slight but not statistically significant tendency for fewer Bobwhites to be heard in the low-lying habitats (Fig. 1). Table 2. Ecological site preference of Northern Bobwhites within the study ranch in the South Texas Plains ecoregion, April 2004–2014. * indicates selected, † indicates avoided. % of calling area Ecological sites within ten 50-ha survey circles % of Bobwhites heard χ2 value Clay Flat 12.78 9.20 1.00 Clay Loam 45.35 26.31 7.99† Sandy Loam 2.02 0.86 0.67 Sandy 39.69 63.64 14.45* sum χ2 = 24.11 df = 3 P < 0.001 Figure 1. Distribution of Northern Bobwhites on ecological sites on 4 ranches in the South Texas Plains during spring 2004−2013. Study ranch in black, additional ranches in grey: ranch H (dark grey), ranch W (light grey), ranch S (mid-level grey). Southeastern Naturalist S.M. Cooper and S.S. Sieckenius 2016 Vol. 15, No. 3 388 Distribution and habitat selection of Wild Pigs The Wild Pigs fitted with GPS collars included 1 adult boar, 8 subadult males, and 7 adult and subadult females. We did not sedate the animals for collaring, and thus could not weigh them, but we determined that shoulder height of these animals ranged from 84 cm to 61 cm (mean = 64 ± 8 cm). Wild Pigs were more often located in habitats with clay soils than in those with clay-loam or sandy-loam soils (χ2 2 = 43.13, P < 0.001). We could not assess use of sandy soils because none of the GPS-collared Wild Pigs crossed the highway to access the 961-ha Sandy ecological site favored by Bobwhites. However, we rarely saw signs of rooting in this area, suggesting that Wild Pigs were not abundant within this area with sandy soil. The distribution of Wild Pigs was consistently associated with selection for proximity to water sources (χ2 8= 91.71, P < 0.001). The ecological sites preferred by Wild Pigs were Clay Flat, and to a lesser degree, Claypan Prairie. Non-preferred sites included Clay Loam and to a lesser extent Rolling Hardland, Grey Sandy Loam, and Sandy Loam sites (Table 3). There was some variation in the distribution of Wild Pigs during the early (spring) compared to the late (summer) breeding season of Bobwhites. During spring, preference of Wild Pigs for Clay Flats was not evident. Instead, Wild Pigs extensively used weedy, fallow fields planted within Clay Loam ecological sites, and thus, showed a preference for this habitat type. During summer, Wild Pigs selected low-lying Clay Flat and Claypan Prairie ecological sites and tended to avoid upland areas including Clay Loam, and to a lesser extent Rolling Hardland, Grey Sandy Loam, and Sandy Loam sites. Landscape features also influenced the distribution of Wild Pigs (Table 4). They were strongly attracted to water sources and riparian zones, but neither selected nor avoided ranch roads. Although shrubland covered 82% of the ranch, only 1/3 of Wild Pig locations were in this type, indicating avoidance of these extensive areas (χ2 1 = 58.13, P < 0.001). Cultivated fields constituted less than 3% of the study area. In spring, Wild Pigs heavily used these fallow grain-fields, particularly at night (75.9 Table 3. Seasonal habitat use and selection by Wild Pigs in the South Texas Plains ecoregion during spring (n = 10), and summer (n = 6), 2004–2006. * indicates selected, † indicates avoided. % of Spring Summer Ecological site area % χ2 % χ2 Clay Flat 6.13 8.62 1.01 29.20 86.54* Saline Clay 7.91 3.51 2.45 13.60 4.08 Claypan Prairie 7.78 8.79 0.13 22.50 27.62* Rolling Hardland 13.10 6.23 3.63 4.25 6.01 Clay Loam 47.20 67.4 8.60* 15.90 20.72† Gray Sandy Loam 8.66 1.20 6.43† 0.34 Sandy Loam 4.84 0.29 4.28† 0.13 4.58 Water 0.59 3.78 17.27* 7.52 81.50* sum χ2 43.80 231.39 df 7 7 P less than 0.001 less than 0.001 Southeastern Naturalist 389 S.M. Cooper and S.S. Sieckenius 2016 Vol. 15, No. 3 ± 23.7% of locations). Wild Pigs tended to spend slightly less time (10.6%) in riparian areas at night than during the day, but variability between individuals was high, and overall differences in distribution in riparian areas and ecological sites between day and night were not significant. Discussion Combining data from separate studies for purposes beyond their original objectives can provide useful if not perfect information at a fraction of the time and cost of initiating new studies. Our investigation, which combined long-term survey results on Bobwhites with a former GPS study of Wild Pig distribution on a large ranch in the South Texas Plains, has identified comparative use and selection of ecological sites common to the ecoregion by the 2 species. However, differences in survey techniques used for the species, and inability to modify the distribution of survey sites, resulted in an unsatisfactory gap in the data concerning use of areas of deep sandy soils by Wild Pigs. Although Bobwhites and Wild Pigs are to some extent both habitat generalists (Graves 1984, Guthery 1999) and can make use of most of the ecological sites within the rangeland, their preferred habitats were distinctly different. Wild Pigs selected areas with clay soils, often near drainages, whereas Bobwhites were most abundant on upland areas with deep sandy soils. The preference of Bobwhites for sandy rather than clay-based soils is consistent with prior literature (Fulbright et al. 1990, Lehmann 1984). Sandy soils tend to support prairie with interspersed mottes of woody plants that provide better distribution of feeding sites and cover for Bobwhites (Guthery 1986, Hernández and Peterson 2007) than the shrub-dominated clay and clay-loam soils. Also, unlike on clay loam soils, there was little invasion by exotic grasses on the sandy soils. Non-native grasses provide poor brood habitat for Bobwhites due to scarcity of insects and obstruction to movement (Sands et al. 2012). Unfortunately for this study, the area of deep sandy soil was divided from the majority of the ranch by a highway bordered by net-wire fencing. The GPScollared Wild Pigs never crossed the highway; thus, we could not determine the extent to which they would have used the relatively uncommon Sandy ecological sites favored by Bobwhites. However, the scarcity of signs of rooting by Wild Pigs in the Sandy areas, and the low use of the Sandy Loam ecological sites, which are Table 4. Influence of landscape features on the seasonal distribution of Wild Pigs in the South Texas Plains Ecoregion during spring (n = 10) and summer (n = 6) 2004–2006. * indicates selected, † indicates avoided. % of Spring Summer Landscape feature area % χ2 % χ2 Σ χ2 df P Road with 20-m buffer 10.54 8.35 0.46 12.68 0.43 0.89 1 N/S Riparian 50-m buffer from creek 10.14 27.28 28.95* 50.53 60.79* 189.74 1 less than 0.001 Water with 50-m buffer 2.08 17.90 20.05* 17.34 111.70* 231.75 1 less than 0.001 Cultivated field no buffer 2.94 22.35 128.39* 1.27 0.95 129.34 1 less than 0.001 Shrubland 82.02 31.35 31.30† 35.11 26.83† 58.13 1 less than 0.001 Southeastern Naturalist S.M. Cooper and S.S. Sieckenius 2016 Vol. 15, No. 3 390 similarly dry upland areas, suggest that Wild Pigs probably do not selectively use areas of sandy soils. The greatest overlap in habitat selection by Wild Pigs and Bobwhites occurred early in the breeding season when Wild Pigs showed selection for Clay Loam ecological sites. These sites are naturally vegetated with shrubland and, while not highly preferred by Bobwhites, these extensive areas are used for nesting. However, most locations of Wild Pigs within Clay Loam areas were not in native vegetation but were within fallow fields that were too sparsely vegetated to be suitable nesting habitat for Bobwhites. Accordingly, the presence of small, cultivated plots within rangeland may reduce the impact of Wild Pigs on nesting Bobwhites by attracting them away from the native vegetation where quail may have nests. Wild Pigs are known to favor cultivated crop fields when available (Baber and Coblentz 1986, Schley and Roper 2003). By the peak of Bobwhite nesting season June–August, summer temperatures can exceed 35 °C (NOAA 2014), during which period, the Wild Pigs spent over half of their time in low-lying, clay-soil areas, near water and within the shaded riparian areas, a tactic that can prevent overheating (Adkins and Harveson 2007, Graves 1984, Ilse and Hellgren 1995). Even at night when temperatures were cooler, Wild Pigs remained predominantly in riparian areas where food resources were probably more abundant due to higher moisture and productivity (USDA-NRCS 2012). Riparian habitats are not the preferred nesting habitats of Bobwhites (Hiller et al. 2007) due to the dense vegetation and risk of seasonal flooding (Klimstra and Roseberry 1975); thus, Wild Pigs are unlikely to encounter Bobwhite nests there. On the more mesic areas of clay-loam soils adjacent to creeks and drainages used by Wild Pigs, dense stands of Buffelgrass provided forage and cover for Wild Pigs but poor brood habitat for Bobwhites (Kuvlesky et al. 2002), again causing a spatial separation of the 2 species. In summary, in semi-arid rangeland, differences in habitat use and selection by Bobwhites and Wild Pigs should limit interaction between the species. However, actual rates of depredation of Bobwhite nests by Wild Pigs will be influenced by the spatial distribution of creeks and drainages that provide these opportunistic omnivores with travel routes into the drier upland areas preferred by Bobwhites. Acknowledgments Funding for this study was provided through the Reversing the Quail Decline in Texas Initiative and the Upland Game Bird Stamp Fund based on a collaborative effort between Texas Parks and Wildlife Department and Texas A&M AgriLife Extension Service. The work was also supported by the USDA National Institute of Food and Agriculture, Hatch project (accession no. 174856). We thank member ranches of the South Texas Covey Connection for their long-lasting support and participation in the quail program. Data on Wild Pigs was derived from a larger project supported by the US Department of Agriculture- Cooperative State Research, Education, and Extension Service-National Research Initiative (USDA-CSREES-NRI agreement 2003-35204-13255). We thank our collaborators J.C. Cathey, H.M. Scott, G.R. De La Garza, A.L. Deck, A.L. Silva, and D.L. Alford for permission to use these data. Southeastern Naturalist 391 S.M. Cooper and S.S. Sieckenius 2016 Vol. 15, No. 3 Literature Cited Adkins, R.N., and L.A. Harveson. 2007. Demographic and spatial characteristics of Feral Hogs in the Chihuahuan Desert, Texas. Human–Wildlife Conflicts 1:152–160. Baber, D.W., and B.E. Coblentz. 1986. Density, home range, habitat use, and reproduction in Feral Pigs on Santa Catalina Island. Journal of Mammalogy 67:512–525. Brennan, L.A. 1991. How can we reverse the Northern Bobwhite population decline? Wildlife Society Bulletin 19:544–555. Burger, L.W., D.A. Miller, and R.I. Southwick. 1999. Economic impact of Northern Bobwhite hunting in the southeastern United States. Wildlife Society Bulletin 27:1010–1018. Byers, C.R., R.K. Steinhorst, and P.R. Krausman. 1984. Clarification of a technique for analysis of utilization–availability data. Journal of Wildlife Management 48:1050–1053. Connor, J.R. 2007. Economic aspects of Texas quails. Pp. 313–326, In L.A. Brennan (Ed.). Texas Quails. Texas A&M University Press, College Station, TX. 491 pp. Cooper, S.M. 2006. Reducing Feral Hog activity near deer feeders: Comparing cottonseed and pelleted supplement. Pp. 78–84, In J.W. Cain III and P.R. Krausman (Eds.). Managing Wildlife in the Southwest, New Challenges for the 21st Century. Southwestern Section of The Wildlife Society, Tucson, AZ. 142 pp. Cooper, S.M., J.C. Cathey, D.L. Alford, and S.S. Sieckenius. 2009. Influence of rainfall, type of range, and brush management on abundance of Northern Bobwhites (Colinus virginianus) in southern Texas. The Southwestern Naturalist 54:13–18. Cooper, S.M., H.M. Scott, G.R. de la Garza, A.L. Deck, and J.C. Cathey. 2010. Distribution and interspecies contact of Feral Swine and cattle on rangeland in South Texas: Implications for disease transmission. Journal of Wildlife Diseases 46:152–164. Correll, D.S., and M.C. Johnson. 1970. Manual of the Vascular Plants of Texas. Texas Research Foundation, Renner, TX, 1881 pp. Donlan, C.J., K. Campbell, W. Cabrera, C. Lavoie, V. Carrion, and F. Cruz. 2007. Recovery of the Galapágos Rail (Laterallus spilonotus) following the removal of invasive mammals. Biological Conservation 138:520–524. Dreibelis, J.Z., K.B. Melton, R. Aguirre, B.A. Collier, J. Hardin, N.J. Silvy, and M.J. Peterson. 2008. Predation of Rio Grande Wild Turkey nests on the Edwards Plateau, Texas. The Wilson Journal of Ornithology 120:906–910. Fulbright, T.E., D.D. Diamond, J. Rappole, and J. Norwine. 1990. The coastal sand-plain of southern Texas. Rangelands 12:337–340. Gipson, P.S., B. Hlavachick, and T. Berger. 1998. Range expansion of Feral Hogs across the central United States. Wildlife Society Bulletin 26:279–286. Graves, H.B. 1984. Behavior and ecology of Wild and Feral Swine (Sus scrofa). Journal of Animal Science 58:482–493. Griffith, G.E., S.A. Bryce, J.M. Omernik, J.A. Comstock, A.C. Rogers, B. Harrison, S.L. Hatch, and D. Bezanson. 2007. Ecoregions of Texas. Texas Commission on Environmental Quality. Austin, TX, 125 pp. Guthery, F.S. 1986. Beef, brush, and Bobwhites. Quail management in Cattle Country. Caesar Kleberg Wildlife Research Institute Press, Kingsville, TX, 182 pp. Guthery, F.S. 1999. Slack in the configuration of habitat patches for Northern Bobwhites. Journal of Wildlife Management 63:245–250. Haines, A.M., F. Hernández, S.E. Henke and R.L Bingham. 2004. Effects of road-baiting on home range and survival of Northern Bobwhites in southern Texas. Wildlife Society Bulletin 32:401–411. Southeastern Naturalist S.M. Cooper and S.S. Sieckenius 2016 Vol. 15, No. 3 392 Hansen, H.M., and F.S. Guthery. 2001. Calling behavior of Bobwhite males and the callcount index. Wildlife Society Bulletin 29:145–152. Hernández, F., and M.J. Peterson. 2007. Northern Bobwhite ecology and life history. Pp. 40–64, In L.A. Brennan (Ed.). Texas Quails. Texas A&M University Press, College Station, TX. 491 pp. Hernández, F., L.A. Brennan, S.J. DeMaso, J.P. Sands, and D.B. Webster. 2013. On reversing the Northern Bobwhite population decline: 20 years later. Wildlife Society Bulletin 37:177–188. Hiller, T.L., F.S. Guthery, A.R. Rybak, S.D. Fuhlendorf, S.G. Smith, W.H. Puckett Jr., and R.A. Baker. 2007. Management implications of cover-selection data: Northern Bobwhite example. Journal of Wildlife Management 71:195–201. Hulbert, I.A., and J. French. 2001. The accuracy of GPS for wildlife telemetry and habitat mapping. Journal of Applied Ecology 38:869–878. Ilse, L.M., and E.C. Hellgren. 1995. Resource partitioning in sympatric populations of Collared Peccaries and Feral Hogs in southern Texas. Journal of Mammalogy 76:784–799. Integrated taxonomic information system (ITIS). 2015. ITIS taxonomic database. Available online at Accessed 15 October 2015. Klimstra, W.D., and J.L. Roseberry. 1975. Nesting ecology of the Bobwhite in southern Illinois. Wildlife Monographs 41:3–37. Kuvlesky, W.P., Jr., T.E. Fulbright, and R. Engel-Wilson. 2002. The impact of invasive exotic grasses on quail in the southwestern United States. Pp 118–128, In S.J. DeMaso, W.P. Kuvlesky Jr., F. Hernández, and M.E. Berger (Eds.). Quail V: The Fifth National Quail Symposium. Texas Parks and Wildlife Department, Austin, TX. 254 pp. Lehman, V.W. 1984. Bobwhites of the Rio Grande Plains of Texas. Texas A&M University Press, College Station, TX. 276 pp. Liu, X., R.M. Whiting Jr., D.S. Parsons, and D.R. Dietz. 2002. Movement patterns of resident and relocated Northern Bobwhites in east Texas. Pp. 168–172, In S.J. DeMaso, W.P. Kuvlesky Jr., F. Hernández, and M.E. Berger (Eds.). Quail V: The Fifth National Quail Symposium. Texas Parks and Wildlife Department, Austin, TX 254 pp. McDonald, J.H. 2014. Handbook of Biological Statistics. Available online at http://www. Accessed 9 March 2016. Mellish, J.M., A. Sumrall, T.A. Campbell, B.A. Collier, W.H. Neill, B. Higginbotham, and R.R. Lopez. 2014. Simulating potential population growth of Wild Pig, Sus scrofa, in Texas. Southeastern Naturalist 13:367–376. Miller, B., and K.J. Mullette. 1985. Rehabilitation of an endangered Australian bird: The Lord Howe Island Woodhen, Tricholinas sylvestris (Sclater). Biological Conservation 34:55–95. Moen, R., J. Pastor, and Y. Cohen. 1997. Accuracy of GPS telemetry-collar locations with differential correction. Journal of Wildlife Management 61:530–539. National Oceanic and Atmospheric Administration (NOAA). 2014. National Weather Service. Available online at http:// Accessed 24 November 2014. Neu, C.W., C.R. Byers, and J.M. Peak. 1974. A technique for analysis of utilization–availability data. Journal of Wildlife Management 38:541–545. Nyenhuis, H. 1991. Predation between Woodcock (Scolopax rusticola L.), game of prey, and Wild Boar (Sus scrofa) L. Allgemeine Forst-und Jagd-Zeitung, 162:174–180. Petty, B.D., S.L. Locke, R.R. Lopez, M.J. Peterson, J.C. Cathey, and N.J. Silva. 2007. Effects of Feral Hog control on nest fate of Eastern Wild Turkey in the Post Oak Savanna of Texas. Proceedings of the National Wild Turkey Symposium 9:169–172. Southeastern Naturalist 393 S.M. Cooper and S.S. Sieckenius 2016 Vol. 15, No. 3 Rollins, D., and J. Carroll. 2001. Impacts of predation on Northern Bobwhite and Scaled Quail. Wildlife Society Bulletin 29:39–51. Rollins, D., J. Brooks, N. Wilkins, and D. Ransom Jr. 2005. Counting quail. Publication B-6173. Texas AgriLife Extension Service. College Station, TX. 12 pp. Rollins, D.B., J. Higginbotham, K.A. Cearly, and N.R. Wilkins. 2007. Appreciating Feral Hogs: Extension education for diverse stakeholders in Texas. Human–Wildlife Conflicts 1:192–198. Sands, J.P., L.A. Brennan, F. Hernández, W.P. Kuvlesky Jr., J.F. Gallagher, and D.C. Ruthven III. 2012. Impacts of introduced grasses on breeding-season habitat use by Northern Bobwhite in the South Texas plains. Journal of Wildlife Management 76:608–618. Sauer, J.R., J.E. Hines, J.E. Fallon, K.L. Pardieck, D.J. Ziolkowski Jr., and W.A. Link. 2014. The North American breeding bird survey, results, and analysis 1966–2012. Version 02.19.2014. USGS Patuxent Wildlife Research Center, Laurel, MD. Available online at Accessed 24 November 2014. Schley, L., and T. Roper. 2003. Diet of the Wild Boar, Sus scrofa, in Western Europe, with particular reference to consumption of agricultural crops. Mammal Review 33:43–56. Taylor, R. 1991. The Feral Hog in Texas. Texas Parks and Wildlife Department, Austin, TX. 20 pp. Taylor, R. 1993. History and distribution of Feral Hogs in Texas. Pages. 17–25, In C.W. Hanselka and J.F. Cadenhead (Eds.). Feral Swine: A Compendium for Resource Managers. Texas Agricultural Extension Service, Kerrville, TX. 169 pp. Texas Natural Resources Information System (TNRIS). 2014. Maps and data. Available online at Accessed 24 November 2014. Texas Parks and Wildlife Department (TPWD). 2014. Quail in Texas: Forecast 2014–2015. Available online at forecast. Accessed 24 November 2014. Timmons, J., B. Higginbotham, R. Lopez, J. Cathey, J. Mellish, J. Griffin, A. Sumrall, and K. Skow. 2012. Feral Hog population growth, density, and harvest in Texas. Publication SP-472. Texas A&M AgriLife, College Station, TX. 5 pp. Tolleson, D., D. Rollins, W. Pinchak, M. Ivy, and A. Hierman. 1993. Impact of Feral Hogs on ground-nesting gamebirds. Pp. 76–83, In C.W. Hanselka and J.F. Cadenhead, (Eds.). Feral Swine: A Compendium for Resource Managers. Texas Agricultural Extension Service, Kerrville, TX. 169 pp. US Department of Agriculture-Natural Resources Conservation Service (USDA-NRCS). 2011. Ecological Site Information System (ESIS). Available online at https://esis. Accessed 15 October 2015. USDA- NRCS. 2012. Web soil survey. Available online at Accessed 24 November 2014. West, B.C., A.L. Cooper, and J.B. Armstrong. 2009. Managing Wild Pigs: A technical guide. Human–Wildlife Interactions Monographs 1:1–55. Wilson, D.E., and D.M. Reeder (Eds.). 2005. Mammal Species of the World: A Taxonomic and Geographic Reference. 3rd Edition. Johns Hopkins University Press, Baltimore, MD. 2142 pp.