Invasive Wild Pigs as Primary Nest Predators for Wild Turkeys

Abstract

similar to natural turkey nests 34. Additionally, simulated nest studies allow for assessment of the influence of the density of nests on nest depredation 35. We used simulated wild turkey nests to evaluate the magnitude of nest predation by wild pigs relative to native nest predators throughout the nesting season in 2016. We also simulated differing densities of nests to evaluate for changes in the frequency of nest predation. Our first objective was compare the frequency of nest consumption by wild pigs to that of native nest predators. Secondly, we assessed the role of seasonality and density of nests in the depredation of nests by wild pigs. Finally, we evaluated differences in consumption of nests by sex and age of wild pigs. Our results will inform efforts to mitigate the impacts of wild pigs on wild turkeys. Methods Study area. Our study area was located in south-central Texas (Bexar County), USA (Latitude 29.622 N, Longitude 98.572 W). Specifically, we worked on Camp Bullis Military Reserve, an 11,000 ha military training base that is bordered by both urban and rural ecosystems. Topography on Camp Bullis is typical of the Edwards Plateau: rolling hills with limestone outcrops and rocky soils 36. Vegetation is an oak woodland and grassland matrix 37,38. Streams and pools are available seasonally during periods of high precipitation. Camp Bullis contains populations of both wild pigs and Rio Grande wild turkey (M. gallopavo intermedia), as well as potential nest predators including raccoons (Procyon lotor), gray foxes (Urocyon cinereoargenteus), coyotes (Canis latrans), bobcats (Lynx rufus), opossums (Didelphis virginiana), striped skunks (Mephitis mephitis), armadillos (Dasypus novemcinctus), corvids, and snakes 23,28. In 2006, a suspected release or immigration from surrounding properties of wild pigs occurred on Camp Bullis, resulting in abundant wild pigs throughout the study area (M. L. Cooksey, U.S. Army Environmental Command, personal communication). In 2017, the density of wild pigs was reported to average 3.5 wild pigs per km 2 39. capture and monitoring of wild pigs. Methods for this study were similarly reported for a simultaneous study 23. We captured wild pigs using corral and box traps baited with whole-kernel corn between 15 January and 15 March 2016. We immobilized adult wild pigs (estimated to be >45 kg) using an intramuscu

Spatiotemporal overlap with invasive wild pigs (Sus scrofa) varies by species and season in a temperate ecosystem

“…We predicted that armadillo and turkey spatial overlap with wild pigs would be greatest in the fall, but armadillos were instead positively associated with wild pigs in the spring and turkeys were positively associated with wild pigs in the summer. Spatial overlap with turkeys outside of nesting season may not be of great concern, but overlap should be monitored across years given the detrimental effects wild pigs could have when turkeys nest in the spring (Sanders et al, 2020). Wild pigs in our study area had low temporal overlap with turkeys, whereas higher spatial overlap between wild pigs and bobcats, raccoons, and armadillos did not appear mediated by diel activity partitioning.…”

“…Prior research suggests the occurrence (O'Brien et al, 2019) and abundance (Stevens, 1996) of coyotes and wild pigs are positively correlated, but the only significant relationship we found between coyote site use and wild pig activity was a negative one in the fall. Although farrowing occurs throughout the year, most wild pigs in our study area were likely born in the winter and spring (VerCauteren et al, 2020), so we would expect wild pig activity to have a positive effect on coyote site use during these seasons if wild pigs benefit coyotes. However, Keiter et al (2017) and Chinn et al (2021) documented fairly low coyote predation on juvenile wild pigs in South Carolina, and concurrent research in our study area found that wild pig was a minor component (≤5%) of coyote diet across seasons (Jensen et al, In review).…”

“…Wild pigs can also indirectly compete with other species through resource exploitation, either by destroying habitat with their rooting behavior or consuming shared resources (Singer et al, 1984; Sweitzer & Van Vuren, 2002; Yarrow, 1987). While their diet is dominated by plant matter, wild pigs also scavenge carrion, consume invertebrates and small vertebrates while rooting (Ballari & Barrios‐García, 2014), and depredate bird (Sanders et al, 2020) and reptile (Engeman et al, 2016) nests, all of which can reduce food resources or survival of other animals. This dietary plasticity likely aids the persistence of wild pigs outside of their native range in Eurasia and northern Africa (Ballari & Barrios‐García, 2014).…”

The wild boar Sus scrofa as a threat to ground‐nesting bird species: an artificial nest experiment

“…We alternated different egg sizes and egg‐shell patterns (affecting egg visibility and palatability: Castilla et al ., 2007) because they may be differently targeted by predators (Svobodová et al ., 2012; Bravo et al ., 2020). During all artificial nest deployment operations, we wore clean boots and latex gloves while handling equipment, to minimize the addition of human scent (Arbeiter & Franke, 2018; Sanders et al ., 2020). Artificial nests may be more attractive to predators than natural ones, because they are often placed on trails, and because of the absence of adults defending, the clutch may increase predation rate (Bravo et al ., 2020).…”

“…Nest destruction by wild boar has been assessed by recording rooting activity and signs of presence around nests after egg hatching (Henry, 1969; Crome & Moore, 1990; Campos, 1993; Fordham et al ., 2006; Padyšáková et al ., 2011; Kambourova, 2012; Baccetti & Puglisi, 2013; Sanders et al ., 2020), by analyzing tooth marks on plasticine eggs in artificial nests (Wood & Barrett, 1979; Duarte & Vargas, 2001; Purger & Meszaros, 2006; Purger et al ., 2008; Padyšáková et al ., 2011; Svobodová et al ., 2012; Carpio et al ., 2014, 2016; Senserini & Santilli, 2016), or anecdotally reported (Stegeman, 1938; Challies, 1975; Pavlov et al ., 1992). In one case, a nest with young birds was found in the stomach of a killed wild boar (Giménez‐Anaya et al ., 2008).…”