Fall and Winter Diets of Eastern Gray Squirrels in a Seasonally Flooded Ecosystem in Alabama

Wilson, Sarah Beth; Steury, Todd D.; Gitzen, Robert A.; Ditchkoff, Stephen S.

doi:10.1656/058.019.0414

Cited by 4 publications

(4 citation statements)

References 11 publications

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“…Following wild pig removal, consumption of acorns by squirrels nearly doubled. Grey squirrels are hard mast specialists and rely heavily on acorns for their dietary needs during winter (Wilson et al 2020). Population density of grey squirrels are linked to acorn availability and populations have been known to crash when acorns are unavailable (McShea 2000).…”

Section: Resultsmentioning

confidence: 99%

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Impacts of wild pigs on acorn availability as a food source for native wildlife

Fay,

Zenas,

Smith

et al. 2023

Wildlife Res.

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Context. 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). Aims. Our objective was to estimate the consumption of acorns by wild pigs relative to that of other native wildlife species. Methods. 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/km 2 . 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. Key results. 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). Key conclusions. 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. Implications. 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.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Impacts of wild pigs on acorn availability as a food source for native wildlife

Fay,

Zenas,

Smith

et al. 2023

Wildlife Res.

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“…When we detected a squirrel's radiotransmitter emitting a mortality signal, we attempted to locate the squirrel as soon as possible. Squirrels with a mortality signal were assigned to the “confirmed and probable” mortality category based on either the presence of a carcass (i.e., confirmed) or significant evidence of a mortality event in the absence of a carcass (e.g., deep, rounded bite marks on the collar assembly, large amounts of squirrel fur, or evidence the collar assembly was removed by a human; Adams et al, 2004 ; Tebo & Norton, 2017 ; Wilson et al, 2019 ). When possible, we tried to ascertain the cause of mortality (McCleery et al, 2008 ).…”

Section: Methodsmentioning

confidence: 99%

“…or significant evidence of a mortality event in the absence of a carcass (e.g., deep, rounded bite marks on the collar assembly, large amounts of squirrel fur, or evidence the collar assembly was removed by a human; Adams et al, 2004;Tebo & Norton, 2017;Wilson et al, 2019). When possible, we tried to ascertain the cause of mortality (McCleery et al, 2008).…”

Section: Translocation Experimentsmentioning

confidence: 99%

Rural selection drives the evolution of an urban–rural cline in coat color in gray squirrels

Cosentino,

Vanek,

Gibbs

2023

Ecology and Evolution

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Phenotypic differences between urban and rural populations are well‐documented, but the evolutionary processes driving trait variation along urbanization gradients are often unclear. We combined spatial data on abundance, trait variation, and measurements of fitness to understand cline structure and test for natural selection on heritable coat color morphs (melanic, gray) of eastern gray squirrels (Sciurus carolinensis) along an urbanization gradient. Population surveys using remote cameras and visual counts at 76 sites along the urbanization gradient revealed a significant cline in melanism, decreasing from 48% in the city center to <5% in rural woodlands. Among 76 squirrels translocated to test for phenotypic selection, survival was lower for the melanic than gray morph in rural woodlands, whereas there was no difference in survival between color morphs in the city. These results suggest the urban–rural cline in melanism is explained by natural selection favoring the gray morph in rural woodlands combined with relaxed selection in the city. Our study illustrates how trait variation between urban and rural populations can emerge from selection primarily in rural populations rather than adaptation to novel features of the urban environment.

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Behavioral adaptations of scatterhoarders to seasonal flooding

et al. 2023

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Scatterhoarder responses to factors that influence stored food (i.e. flooding) is important given the strong reliance on hoarded food for survival. We examined how eastern gray squirrels (Sciurus carolinensis, Gmelin 1778) have adapted to a seasonally flooded ecosystem in Alabama. Our study area was dry September – November and flooded the rest of the year. We predicted squirrels would respond to flooding by storing food in areas that stay dry during winter, seasonally shifting to dry habitat, or decreasing the amount of hard mast in their winter diet. We also examined previously reported survival differences between the dry and flooded seasons. During the dry season, 72% of acorns were buried in areas that later flooded. Habitat use did not change significantly during the flooded and dry seasons; however, squirrels used habitat that stayed dry during flooding to a greater degree during non-flood seasons. The amount of hard mast in the diet did not change significantly between the dry and flooded seasons. However, squirrels were more likely to die during the flooded season (P = 0.02). We did not find any behavioral adaptations to seasonal flooding. Further research is needed to fully understand the effects of fluctuating environmental conditions on scatterhoarders.

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Fall and Winter Diets of Eastern Gray Squirrels in a Seasonally Flooded Ecosystem in Alabama

Cited by 4 publications

References 11 publications

Impacts of wild pigs on acorn availability as a food source for native wildlife

Impacts of wild pigs on acorn availability as a food source for native wildlife

Rural selection drives the evolution of an urban–rural cline in coat color in gray squirrels

Behavioral adaptations of scatterhoarders to seasonal flooding

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