Impacts of wild pigs on acorn availability as a food source for native wildlife
Arielle S. Fay
A * , Stephen J. Zenas A , Mark D. Smith A and Stephen S. Ditchkoff A
A College of Forestry, Wildlife and Environment, Auburn University, Auburn, AL 36849, USA.
Abstract
Wild pigs (Sus scrofa) are a non-native invasive species that causes millions of dollars in damage each year to agriculture in the United States of America, destroys native plant communities, and competes with native wildlife for seasonally available pulse resources such as acorns. Despite many anecdotal observations and diet studies suggesting wild pigs reduce acorn availability for other wildlife species, no studies have comparatively examined acorn consumption among species in a natural environment (i.e. competition).
Our objective was to estimate the consumption of acorns by wild pigs relative to that of other native wildlife species.
We established 40 monitoring stations beneath acorn-producing trees in a 3406-ha study area in eastern Alabama with an approximate density of 9 pigs/km2. At each monitoring station, we placed five acorns on a 1-m × 1-m sand pad and positioned a game camera to record acorn fate during 2-week intervals once a month from September to February 2018–2019 and 2019–2020. Cameras were set to capture images once every minute continuously during the survey period. Additionally, we constructed acorn traps from 18.9-L plastic buckets to estimate the timing and relative amounts of acorns that were potentially available for consumption at each monitoring station.
From approximately 7.3 million camera images, we observed 15 wildlife species consuming 707 acorns over the 2 years. Aside from animal consumption, acorn fate was categorised as lost due to flooding (n = 153), remaining on the sand pad at time of camera failure (n = 720), or not consumed during the sampling period (n = 536).
Top acorn consumers were squirrel (Sciurus spp.), white-tailed deer (Odocoileus virginianus), raccoon (Procyon lotor), and wild pig. In the 2018–2019 sampling period, wild pigs consumption accounted for 23.4% (n = 87) of the total consumed acorns. After wild pig removal efforts were initiated in the summer and autumn of 2019, wild pigs consumed only 7.2% (n = 24) of consumed acorns.
Wild pigs consume a significant number of acorns and likely reduce the availability of this pulse resource for other native wildlife species and may potentially influence oak regeneration.
Keywords: acorns, Alabama, camera survey, competition, invasive species, native wildlife, Sus scrofa, wild pig.
References
Anderson A, Slootmaker C, Harper E, Holderieath J, Shwiff SA (2016) Economic estimates of feral swine damage and control in 11 US states. Crop Protection 89, 89-94.
| Crossref | Google Scholar |
Anderson WM, Boughton RK, Wisely SM, Merrill MM, Boughton EH, Robeson MS, Piaggio AJ (2018) Using DNA metabarcoding to examine wild pig (Sus scrofa) diets in a subtropical agro-ecosystem. Proceedings of the Vertebrate Pest Conference 28, 90-95.
| Crossref | Google Scholar |
Barrett RH (1978) The feral hog at Dye Creek Ranch, California. Hilgardia 46, 283-355.
| Crossref | Google Scholar |
Barrett RH (1982) Habitat preferences of feral hogs, deer, and cattle on a Sierra Foothill Range. Journal of Range Management 35, 342-346.
| Crossref | Google Scholar |
Beasley JC, Ditchkoff SS, Mayer JJ, Smith MD, Vercauteren KC (2018) Research priorities for managing invasive wild pigs in North America. The Journal of Wildlife Management 82, 674-681.
| Crossref | Google Scholar |
Beckerton PR, Middleton ALA (1982) Effects of dietary protein levels on ruffed grouse reproduction. The Journal of Wildlife Management 46, 569-579.
| Crossref | Google Scholar |
Berger J (1985) Interspecific interactions and dominance among wild Great Basin ungulates. Journal of Mammalogy 66, 571-573.
| Crossref | Google Scholar |
Bevins SN, Pedersen K, Lutman MW, Gidlewski T, Deliberto TJ (2014) Consequences associated with the recent range expansion of nonnative feral swine. BioScience 64, 291-299.
| Crossref | Google Scholar |
Bolds SA, Lockaby BG, Ditchkoff SS, Smith MD, VerCauteren KC (2021) Impacts of a large invasive mammal on water quality in riparian ecosystems. Journal of Environmental Quality 50, 441-453.
| Crossref | Google Scholar |
Bradley EA, Lockaby G (2021) Invasive wild pigs: a significant disturbance in coastal forests. Forests 12, 1042.
| Crossref | Google Scholar |
Campbell TA, Long DB (2009) Strawberry-flavored baits for pharmaceutical delivery to feral swine. Journal of Wildlife Management 73, 615-619.
| Crossref | Google Scholar |
Cutini A, Chianucci F, Chirichella R, Donaggio E, Mattioli L, Apollonio M (2013) Mast seeding in deciduous forests of the northern Apennines (Italy) and its influence on wild boar population dynamics. Annals of Forest Science 70, 493-502.
| Crossref | Google Scholar |
Eiler JH, Wathen WG, Pelton MR (1989) Reproduction in black bears in the southern Appalachian Mountains. The Journal of Wildlife Management 53, 353-360.
| Crossref | Google Scholar |
Elston JJ, Hewitt DG (2010) Intake of mast by wildlife in Texas and the potential for competition with wild boars. The Southwestern Naturalist 55, 57-66.
| Crossref | Google Scholar |
Fournier-Chambrillon C, Maillard D, Fournier P (1995) Diet of the wild boar (Sus scrofa L.) inhabiting the Montpellier garrigue. Journal of Mountain Ecology 3, 174-179.
| Google Scholar |
Fox JF (1982) Adaptation of gray squirrel behavior to autumn germination by white oak acorns. Evolution 36, 800-809.
| Crossref | Google Scholar |
Geisser H (1998) The wild boar (Sus scrofa) in the Thurgau (Northeastern Switzerland): population status, damages and the influence of supplementary feeding on damage frequency. Gibier Faune Sauvage 15, 547-554.
| Google Scholar |
Goodrum PD, Reid VH, Boyd CE (1971) Acorn yields, characteristics, and management criteria of oaks for wildlife. The Journal of Wildlife Management 35, 520-532.
| Crossref | Google Scholar |
Harlow RF, Whelan JB, Crawford HS, Skeen JE (1975) Deer foods during years of oak mast abundance and scarcity. The Journal of Wildlife Management 39, 330-336.
| Crossref | Google Scholar |
Havera SP, Smith KE (1979) A nutritional comparison of selected fox squirrel foods. The Journal of Wildlife Management 43, 691-704.
| Crossref | Google Scholar |
Henry VG, Conley RH (1972) Fall foods of European wild hogs in the Southern Appalachians. The Journal of Wildlife Management 36, 854-860.
| Crossref | Google Scholar |
Johnson AS, Hale PE, Ford WM, Wentworth JM, French JR, Anderson OF, Pullen GB (1995) White-tailed deer foraging in relation to successional stage, overstory type and management of southern Appalachian Forests. The American Midland Naturalist 133, 18-35.
| Crossref | Google Scholar |
Macarthur R, Levins R (1967) The limiting similarity, convergence, and divergence of coexisting species. The American Naturalist 101, 377-385.
| Crossref | Google Scholar |
Massei G, Genov PV, Staines BW (1996) Diet, food availability and reproduction of wild boar in a Mediterranean coastal area. Acta Theriologica 41, 307-320.
| Crossref | Google Scholar |
McDonald RI, Peet RK, Urban DL (2003) Spatial pattern of Quercus regeneration limitation and Acer rubrum invasion in a Piedmont forest. Journal of Vegetation Science 14, 441-450.
| Crossref | Google Scholar |
McDonough MT, Ditchkoff SS, Smith MD, Vercauteren KC (2022) A review of the impacts of invasive wild pigs on native vertebrates. Mammalian Biology 102, 279-290.
| Crossref | Google Scholar |
McKee S, Anderson A, Carlisle K, Shwiff SA (2020) Economic estimates of invasive wild pig damage to crops in 12 US states. Crop Protection 132, 105105.
| Crossref | Google Scholar |
McShea WJ (2000) The influence of acorn crops on annual variation in rodent and bird populations. Ecology 81, 228-238.
| Crossref | Google Scholar |
McShea WJ, Schwede G (1993) Variable acorn crops: responses of white-tailed deer and other mast consumers. Journal of Mammalogy 74, 999-1006.
| Crossref | Google Scholar |
Nixon CM, McClain MW, Donohoe RW (1975) Effects of hunting and mast crops on a squirrel population. The Journal of Wildlife Management 39, 1-25.
| Crossref | Google Scholar |
Poudyal NC, Caplenor C, Joshi O, Maldonado C, Muller LI, Yoest C (2017) Characterizing the economic value and impacts of wild pig damage on a rural economy. Human Dimensions of Wildlife 22, 538-549.
| Crossref | Google Scholar |
Rogers L (1976) Effects of mast and berry crop failures on survival, growth, and reproductive success of black bears. In ‘Transactions of the 41st North American wildlife and natural resources conference, 21–25 March 1976, Washington, DC, USA’. pp. 431–438. (Wildlife Management Institute: Washington, DC, USA)
Rose AK, Greenberg CH, Fearer TM (2012) Acorn production prediction models for five common oak species of the eastern United States. The Journal of Wildlife Management 76, 750-758.
| Crossref | Google Scholar |
Servello FA, Kirkpatrick RL (1988) Nutrition and condition of ruffed grouse during the breeding season in southwestern Virginia. The Condor 90, 836-842.
| Crossref | Google Scholar |
Strickland BK, Smith MD, Smith AL (2020) Wild pig damage to resources. In ‘Invasive wild pigs in North America’. (Eds KC VerCauteren, JC Beasley, SS Ditchkoff, JJ Mayer, GJ Roloff, BK Strickland) pp. 143–168. (Taylor & Francis Group: Boca Raton, FL, USA) doi:10.1201/b22014-7
Taylor RB, Hellgren EC (1997) Diet of feral hogs in the Western South Texas plains. The Southwest Naturalist 42, 33-39.
| Google Scholar |
Taylor RB, Hellgren EC, Gabor TM, Ilse LM (1998) Reproduction of feral pigs in Southern Texas. Journal of Mammalogy 79, 1325-1331.
| Crossref | Google Scholar |
Wentworth JM, Johnson AS, Hale PE, Kammermeyer KE (1992) Relationships of acorn abundance and deer herd characteristics in the Southern Appalachians. Southern Journal of Applied Forestry 16, 5-8.
| Crossref | Google Scholar |
Wilson SB, Steury TD, Gitzen RA, Ditchkoff SS (2020) Fall and winter diets of eastern gray squirrels in a seasonally flooded ecosystem in Alabama. Southeastern Naturalist 19, 771-780.
| Crossref | Google Scholar |
Wood GW, Roark DN (1980) Food habits of feral hogs in Coastal South Carolina. The Journal of Wildlife Management 44, 506-511.
| Crossref | Google Scholar |
