Consumption Patterns of a Generalist Omnivore: Eastern Box Turtle Diets in the Long Island Pine Barrens

Abstract

Eastern Box Turtles (Terrapene carolina) are diet generalists and as such are predicted to have diverse diets in which familiar, low-quality foods are eaten consistently at low levels, and high-quality foods are rare but eaten whenever available. Previous work showed that they feed opportunistically on seasonally available plants (shoots, leaves, flowers, and fruit), invertebrates, mushrooms, and occasionally carrion. We used fecal samples to test optimal foraging predictions relevant to diet generalists and also whether the Eastern Box Turtle diets varied seasonally in a northeastern U.S. pine-oak habitat. We found that in-depth prey species consumption patterns of six different individuals were similar to those of the sampled population overall. Leaf and stem material was consumed by 100% of the turtles in all months despite being lower-quality than other prey available. Invertebrates were consumed by at least 80% of turtles in every study period; Coleopterans were found more commonly than other invertebrates. Snails were not eaten by more than 20% of the turtles in any study period, and mushroom consumption varied from 31–75% of samples in different study periods. Monthly diet overlap was measured using both Pianka’s Index of Overlap (PIO) and the Morisita–Horn Index (MH). The PIO method indicated that the prey consumption patterns were broadly similar from June–October, while the M–H method showed that only the July vs. August comparison was highly similar. The turtle diets changed only slightly between seasons, and they conform to predictions of diet generalist models usually applied to mammals.

The diet of Florida Box Turtles (Terrapene bauri) in a coastal ecosystem in southwestern Florida

“…We found evidence of turtles eating dragonflies (Odonata) and ants (Formicidae) only during the wet season. Although ants are not considered a primary prey item for box turtles, several studies (Klimstra and Newsome 1960;Worthington et al 2017;Figueras et al 2021) have indicated their presence in the box turtle diet. However, given that a single observation was the only evidence of predation on ants in the study, we cannot discount the possibility of incidental ingestion.…”

The topography of diet: Orientation patch count predicts diet in turtles

“…Turtles occupy a wide range of ecological roles, including ambush predators ( Chelydra serpentina , Alcott et al, 2020), habitat‐engineering herbivores ( Gopherus polyphemus , Richardson & Stiling, 2019), shell‐crushing durophages ( Malaclemys terrapin , Kays et al, 2019), and generalist omnivores ( Terrapene carolina , Figueras et al, 2021). This diversity in diet can be surprising given that upon first observation, turtle rhamphothecae have the same basic shape in all but the most extreme outliers.…”

Food preferences in a generalist pollen feeder: A nutritional strategy mainly driven by plant carbohydrates

“…These strategies have been extensively studied in vertebrates, where generalism at the individual scale is the rule (Bernays and Minkenberg, 1997). Indeed, examples of such generalist feeding strategies at the individual scale can be found in mammals (Wiggins et al, 2006;Cui et al, 2018;Takahashi et al, 2021;Windley et al, 2022), birds (Fargallo et al, 2020;Cady et al, 2021;Oortwijn et al, 2022), reptiles (Figueras et al, 2021), and fishes (Yeager et al, 2014;Laske et al, 2018). In herbivorous insects, however, where most species are specialists (Bernays and Graham, 1988), feeding strategies of generalist species have received much less attention.…”