The Omnivorous Diet of the Western Chicken Turtle (Deirochelys reticularia miaria)

Abstract

Chicken Turtles (Deirochelys reticularia) are morphologically adapted for carnivory, and this specialization has been corroborated by diet studies of the eastern and Florida subspecies (D. r. reticularia and D. r. chrysea, respectively). However, the diet of the western subspecies (D. r. miaria) has not been examined. To investigate this important aspect of this subspecies' ecology, we collected 54 fecal samples from 22 adult D. r. miaria and 13 samples from nine juvenile D. r. miaria in southeastern Oklahoma. White River Crayfish (Procambarus acutus) were found in 88.9% of adult samples (mean of 2.3 crayfish per sample), and appeared to be the dominant food source for adults. There was a significant positive relationship between turtle size and crayfish size, and on average the crayfish were 29.8 mm in carapace length. Insects representing six orders (predominantly Hemiptera and Coleoptera) were found in 57.4% of adult fecal samples. Surprisingly, plants were present in 92.6% of adult fecal samples. While most of the plant matter was unidentifiable, Common Rush (mostly seeds; Juncus effusus), Broadleaf Cattail (Typha latifolia), Giant Cutgrass (seeds; Zizaniopsis miliacea), and Purple-fringed Riccia (Ricciocarpus natans) were identified in several fecal samples. There was a significant difference between the diets of juveniles and adults, with juveniles consuming more insects, fewer crayfish, and fewer plants than adults. These results suggest both that there is an ontogenetic shift in the diet of D. r. miaria and that, unlike the other subspecies, D. r. miaria is demonstrably omnivorous.

Shell variability in the stem turtlesProterochersisspp.

“…The shell of turtles, although relatively conserved structurally among taxa, tends to show considerable variation between individuals (Parker, 1901; Gadow, 1905; Newman, 1906a; Coker, 1910; Lynn, 1937; Młynarski, 1956; Zangerl & Johnson, 1957; Zangerl, 1969; McEwan, 1982; Rothschild, Schultze & Pellegrini, 2013; Cherepanov, 2015, 2016; Farke & Distler, 2015; and many others). This variation may be potentially caused by numerous factors, out of which a suboptimal humidity (Lynn & Ullrich, 1950) or temperature (Yntema, 1970) during incubation, and a low genetic variation (bottleneck) within populations (Velo-Antón, Becker & Cordero-Rivera, 2011; McKnight & Ligon, 2014) were proposed. Expressions of atavistic morphologies were frequently cited as a cause of abnormal shell variants (Gadow, 1905; Newman, 1906b; Grant, 1936a, 1936b), but this always remained rather speculative (Coker, 1905, 1910; Cherepanov, 1989, 2006, 2014) and in most cases it is easy to refute by comparison with the shell composition (number and layout of shell elements) of stem turtles (Gaffney, 1990; Li et al, 2008; Szczygielski & Sulej, 2016, 2018).…”

Dietary Niche of Three Omnivorous Turtle Species in a Northern Florida River: Insights from Stable Isotope Analysis

“…As adults, M. suwanniensis potentially forage on a broader suite of larger prey unavailable to the smaller individuals (Ewert et al 2006). Ontogenetic changes in diet have been well-documented in many other turtle species, including Chelonia mydas (L.) (Green Turtle; Morais et al 2014), Deirochelys reticularia miaria Schwartz (Western Chicken Turtle; McKnight et al 2015), Emydura macquariii kreffii (Gray) (Krefft's River Turtle; Georges 1982), Kinosternon hirtipes Wagler (Rough-footed Mud Turtle; Platt et al 2016), Sternotherus minor (Agassiz) (Loggerhead Musk Turtle; Zappalorti and Iverson 2006), and T. scripta (Bouchard and Bjorndal 2006, Clark and Gibbons 1969). Isotope studies have also detected ontogenetic shifts in Apalone ferox Schneider (Florida Softshell Turtle) populations in lakes in northwestern Florida (Aresco et al 2015), as well as in a Malaclemys terrapin terrapin Schoepff (Northern Diamondback Terrapin) population in southern Barnegat Bay, NJ (Denton et al 2023).…”

Abundance, diet and prey selection of arboreal lizards in a grazed tropical woodland

“…To identify the diet of an organism, dissection of stomach contents (Shine ), stomach flushing (Legler & Sullivan ) or faecal dissection (McKnight et al . ) are relatively instant and inexpensive methods for determining diet. However, each technique has pros and cons: examining stomach contents generally require sacrificed animals or museum specimens; stomach flushing can be harmful to the animal if not done properly; and faecal dissection results can be bias towards organisms with durable exoskeletons, bones and body parts that remain intact after digestion (Rabinowitz & Tuttle ).…”