The Omnivorous Diet of the Western Chicken Turtle (Deirochelys reticularia miaria)
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.
Invertebrate consumption by adult and juvenile Western Chicken Turtles (Deirochelys reticularia miaria) shown as the percent of consumed invertebrates represented by each taxa. Adults from all study sites were combined. Only taxa that comprised at least 1% of all invertebrates are shown (see Table 1).
Plant matter found in the stomachs and guts of two representative White River Crayfish (Procambarus acutus; top) and the plant matter found in the feces of two representative Western Chicken Turtles (Deirochelys reticularia miaria; bottom).
Linear regressions of carapace length against gastric tooth length and carapace length against mandible width for 18 White River Crayfish (Procambarus acutus).
Size distribution of White River Crayfish (Procambarus acutus) that were consumed by Western Chicken Turtles (Deirochelys reticularia miaria).
Linear regression of Western Chicken Turtles' (Deirochelys reticularia miaria) carapace lengths against the carapace length of the largest White River Crayfish (Procambarus acutus) that was consumed by each individual. Large gray circles and the solid line represent all turtles (R2 = 0.302, P = 0.0120). Small black circles and the broken line represent only adult turtles (carapace length >120 mm, R2 = 0.031, P = 0.5305).
Contributor Notes
Associate Editor: J. D. Litzgus.