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Food of the Southern Short-tailed Shrew (Blarina carolinensis) on Cumberland Island, Georgia
John O. Whitaker, Jr. and Carol Ruckdeschel

Southeastern Naturalist, Volume 5, Number 2 (2006): 361–366

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2006 SOUTHEASTERN NATURALIST 5(2):361–366 Food of the Southern Short-tailed Shrew (Blarina carolinensis) on Cumberland Island, Georgia John O. Whitaker, Jr.1,* and Carol Ruckdeschel2 Abstract - The main foods of 73 Blarina carolinensis (southern short-tailed shrews) taken during 2003 and 2004 on Cumberland Island, GA, were the introduced terrestrial amphipod, Talitroides topitotum (Amphipoda, 21.8% volume), larval beetles (Coleoptera, 12.4%), centipedes (Chilopoda, 11.8%), earthworms (Annelida, 9.1%), moth larvae (Lepidoptera, 8.6%), and spiders (Araneae, 7.4%). The primary foods identified in this study were similar to results from a study in South Carolina, except that amphipods, T. topitotum, comprised 21.8% of the Georgia food, but did not occur in the South Carolina sample, and subterranean fungi Endogonaceae made up 16.8% of the South Carolina food, but only 3.8% in Georgia. The importance of amphipods in the diet in coastal Georgia was probably due to the great abundance of these amphipods in the study area. Talitroides topitotum is a terrestrial amphipod of Indo-Pacific origin and this is apparently the first report of this species from Georgia. There was little seasonal variation among the primary foods, but centipedes and ants were eaten most heavily in spring, annelids and spiders in summer, and fungi in winter. Introduction The southern short-tailed shrew, Blarina carolinensis (Bachman), occurs primarily in damp woods throughout the lower elevations in the southeastern United States (Whitaker and Hamilton 1998). Little information has been published on the food of this species. The main food items reported for this species in the Upper Coastal Plain of South Carolina (Whitaker et al. 1994, based on 45 individuals) were slugs and snails (Mollusca, 18% by volume), subterranean fungi (Endogonaceae, 16%), earthworms (Annelida, 15%), adult beetles (Coleoptera, 10%), beetle larvae (Coleoptera, 6%), and spiders (Araneae, 5%). Little vertebrate or plant material was eaten. Two additional studies reported food items consumed by the southern short-tailed shrew, but both are based on much smaller sample sizes. Calhoun (1941) reported beetles (including Scarabaeidae and Coleoptera larvae), moth larvae (Lepidoptera), ants (Formicidae), true bugs (Hemiptera), and slugs (Limacidae) among the food items consumed by nine southern short-tailed shrews from Tennessee. In Florida, insect material, including the remains of a caterpillar in one, were reported based on an assessment of three southern short-tailed shrews (Rand and Host 1942). The purpose of this paper is to present additional information on food consumed by southern short-tailed shrews based on samples collected at 1Department of Ecology and Organismal Biology, Indiana State University, Terre Haute, IN 47809. 2Cumberland Island Museum, PO Box 796, St. Marys, GA 31558. Corresponding author – lswhitak@isugw.indstate.edu. 362 Southeastern Naturalist Vol. 5, No. 2 Cumberland Island, a barrier island off the coast of Georgia. The southern short-tailed shrew is the only shrew definitely occurring on Cumberland Island. The record of a Cryptotis parva (Say) (least shrew) on Cumberland Island by Neuhauser and Baker (1974) was from remains in an owl pellet and it is not known if this individual originated from the island. Materials and Methods This study was conducted on Cumberland Island, a barrier island off the coast of Georgia. The shrews in this study were incidentally caught during 2003–2004 in pitfall traps (sunken buckets) along drift fences during a survey of amphibians and reptiles of the island. The traps were checked once per day. They contained water, thus the shrews were quickly killed. A total of 73 shrews was caught throughout the year: two in autumn (September– November), 39 in winter (December–February), 24 in spring (March–May), and eight in summer (June–August). Trapping was in two locations: a pineoak scrub at the edge of a temporary pond and in a wetland at the head of a wooded swamp. The predominant hardwoods in the trapping areas were various scrub oaks, primarily Quercus myrtifolia Willd. (myrtle oak) and Quercus chapmanii Sarg. (Chapman’s oak) and Acer rubrum L. (red maple) The pines mostly were Pinus elliottii Engelm. (slash pine) and Pinus serotina Michx. (pond pine). Persea borbonia L. Spreng. (bay) also was common. The main understory plants were Serenoa repens (Bartram) Small (saw palmetto), Lyonia lucida (Lamb.) K. Koch (fetterbush), and L. ferruginea (Walter) Nutt. (rusty lyonia). Spartina bakeri Merr. (sand cordgrass) formed the main vegetation in the temporary pond. There were 830 trap-nights in the swamp habitat that yielded 36 shrews and 3696 trapnights in the scrub habitat that yielded 37 shrews (one of the shrews was found dead in the scrub). The stomach of each shrew was removed and its contents were placed in water in a watchglass for identification under a dissecting microscope. The percent volume of each item in each stomach was estimated visually. Data were compiled as percent volume (sum of individual volumes/number of individuals) and percent frequency (percentage of individuals feeding on each item) for each type of food in the sample (Whitaker 1988). Results and Discussion The primary food of 73 southern short-tailed shrews from Cumberland Island, GA (Table 1), was the terrestrial amphipod, Talitroides topitotum (Burt). It formed 21.8% of the volume of food overall, was found in 35.6% of the individuals, and many stomachs contained only amphipods. This fully terrestrial amphipod is of Indo-Pacific origin, and this is apparently its first report in Georgia. It is not known when these amphipods arrived on Cumberland Island, but two species, Talitroides topitotum and T. alluaudi (Chevreux), now are common in some wetlands and low areas. However, 2006 J.O. Whitaker, Jr. and C. Ruckdeschel 363 only T. topitotum was found in the actual study area and was the only one found in stomachs of these shrews. These terrestrial amphipods emerged in profusion at night during rain and wet weather. They were abundant on the ground and were often observed on the vegetation up to a height of about 1 m. There were about four centimeters of them in the sunken cans overnight after a soaking rain. Thus, it is not surprising that they were eaten by shrews in such numbers, and throughout the year (except fall, n = 2). Two other vertebrate species, Rana sphenocephala Cope (Southern Leopard Frogs) and Gastrophryne carolinensis [Holbrook] (Eastern Narrow-mouth Toads), caught at the same site also had eaten T. topitotum (C. Ruckdeschel, unpubl. data). Amphipods have been reported as a food item for at least one other shrew species in eastern North America. Sorex cinereus Kerr (masked shrew) on Bon Portage Island, NS, Canada, ate the littoral scavenging marine amphipod, Platorchestia platensis (Kroyer) (Stewart et al. 1989). Like the amphipod on Cumberland Island, it was very abundant, heavily fed upon, and many stomachs contained only amphipods. However, in Nova Scotia, amphipods and also kelp flies (Coelopidae) occurred in greatest numbers on the beach and decreased in abundance with distance from the beach, whereas Talitroides topitotum on Cumberland Island was abundant only in leaf litter in wetlands away from the beach. The second most abundant item in the diet of southern short-tailed shrews in coastal Georgia was unidentified larval beetles, Coleoptera Table 1. Food of 73 southern short-tailed shrews (Blarina carolinensis) from Cumberland Island, Camden County, GA. Overall Seasonal percent volume Percent Percent Winter Spring Summer Fall Food item volume frequency (n = 39) (n = 24) (n = 8) (n = 2) Amphipoda 21.8 35.6 22.1 21.9 25.6 0.0 Coleopteran larvae 12.4 21.9 13.6 13.5 0.0 25.0 Chilopoda 11.8 31.5 9.5 17.9 8.1 0.0 Annelida 9.1 16.4 8.3 7.5 20.0 0.0 Lepidopteran larvae 8.6 16.4 7.3 8.3 10.6 30.0 Araneae 7.4 23.3 9.2 6.9 1.9 0.0 Mollusca 6.8 11.0 10.5 3.8 0.0 0.0 Endogonaceae 3.8 6.8 6.9 0.4 0.0 0.0 Dipteran larvae 3.6 11.0 2.2 2.1 4.4 45.0 Scarabaeid larvae 3.5 5.5 1.9 7.5 0.0 0.0 Formicidae 3.2 15.1 0.2 9.2 1.3 0.0 Coleopteran adult 2.8 21.9 2.7 0.8 10.0 0.0 Plecoptera? 1.4 1.4 0.0 0.0 12.5 0.0 Insect internal organs 1.2 1.4 2.3 0.0 0.0 0.0 Salientia 1.0 1.4 1.9 0.0 0.0 0.0 Unidentified insect 0.8 8.2 0.4 0.2 4.4 0.0 Dipteran adult 0.3 2.7 0.3 0.0 1.3 0.0 Vegetation 0.2 2.7 0.4 0.0 0.0 0.0 Lygaeidae 0.1 1.4 0.1 0.0 0.0 0.0 Curculionidae 0.1 1.4 0.1 0.0 0.0 0.0 364 Southeastern Naturalist Vol. 5, No. 2 (12.4% volume). The total volume of beetles was 18.7% when larval scarabaeids, adult Coleoptera, and Curculionidae were included (Table 1). Coleopteran larvae were eaten about equally in winter and spring, but were not observed in summer samples, which may have reflected the small sample size (n = 8). Despite their small sample sizes, Whitaker et al. (1994) and Calhoun (1941) also found adult and larval beetles in the foods consumed by southern short-tailed shrews, suggesting the importance of beetles in the diet of this species. Centipedes were the third most important item by volume. Centipedes were eaten most heavily in spring. Centipedes were common within our study area and because they have been reported as a common food of the closely related Blarina brevicauda (Say) (northern short-tailed shrew) (Whitaker and Mumford 1972), the occurrence in the diet of southern shorttailed shrews was not unexpected. Centipedes were also eaten by Sorex cinereus, S. fumeus (Miller), S. hoyi Baird, and S. longirostris Bachman (Whitaker and Cudmore 1987, Whitaker and Ferraro 1963, Whitaker and Mumford 1972). Earthworms are an important food of shrews, especially larger shrews (Whitaker and Cudmore 1987, Whitaker and Ferraro 1963, Whitaker and Mumford 1972), and they were the fourth most abundant food item in this sample, followed by Lepidopteran (moth) larvae, spiders, and molluscs, which are all important foods of many shrews (Whitaker and Cudmore 1987, Whitaker and Ferraro 1963, Whitaker and Mumford 1972, Whitaker et al. 1994). Spiders were eaten throughout the year. Mollusks (slugs and snails) were more heavily eaten in spring than in summer. Spores of Endogonaceae were eaten primarily in winter on Cumberland Island. They often are eaten by shrews, usually in relatively low volume (Whitaker 1962, Whitaker and Cudmore 1987, Whitaker and Ferraro 1963, Whitaker and Mumford 1972, Whitaker et al. 1994). It is clear that shrews and other small mammals feed specifically on this item, rather than simply getting it incidentally with other foods, as in a few individuals the entire stomach may be filled with this item. We suspect that they find it using olfactory clues. Two species of Endogonaceae were seen, one with large black spores and one with tiny yellow spores. Dipteran larvae, which formed a small portion of the diet throughout the year, are commonly eaten by shrews (Whitaker and Cudmore 1987, Whitaker and Mumford 1972, Whitaker et al. 1994). Ants formed 3.2% of the total food, eaten least frequently in winter and most often in spring. Frog remains were found in only one shrew, and this was the only vertebrate in the sample. Various vertebrates are taken occasionally, but are not important shrew foods. Regional comparison There were many similarities, but some differences in the results between our study from coastal Georgia (n = 73) and the results of Whitaker et al. (1994) from South Carolina (n = 45). The diversity of the diet of the 2006 J.O. Whitaker, Jr. and C. Ruckdeschel 365 southern short-tailed shrew was nearly similar in these two studies with 23 food items identified from South Carolina and 20 from coastal Georgia. The major foods reported from these two studies were amphipods, coleopteran larvae, centipedes, earthworms, lepidopteran larvae, spiders, slugs and snails, Endogonaceae, and adult beetles. These comprised 88.1% of the food in our coastal Georgia sample and 79.4% in the South Carolina sample. The biggest difference between the Cumberland and South Carolina samples was that amphipods made up 21.8% of the Cumberland food, but did not occur in the South Carolina sample. This was because of the great prevalence of these amphipods in the study area on Cumberland Island. Most primary food items were eaten by shrews in both samples. This would suggest that they ate similar foods and that many of the differences were related to availability. Some of the larger differences were of the centipedes (11.8% on Cumberland, 0.5% in South Carolina) and Endogonaceae (3.8% on Cumberland, 16.3% in South Carolina). Seasonal variation The winter and spring samples were large enough to be useful, but the summer sample was small, and the fall sample was too small to draw any meaningful conclusions from. It is of interest that in the winter–summer samples, the amphipods formed the largest volume. However, the second highest was different in each of the three, coleopteran larvae in winter, centipedes in spring and annelids in summer. Beetle larvae formed about the same volume in winter and spring, but were absent in summer. Centipedes were most heavily eaten in spring, and formed about twice the volume that they did in winter or summer. Earthworms and spiders were highest in summer; mollusks were highest in winter, absent in summer; and Endogonaceae were highest in winter. Literature Cited Calhoun, J.B. 1941. Distribution and food habits of mammals in the vicinity of the Reelfoot Lake Biological Station. Journal of the Tennessee Academy of Science 16:177–185, 207–225. Mumford, R.E., and J.O. Whitaker, Jr. 1982. Mammals of Indiana. Indiana University Press. Bloomington, IN. 537 pp. Neuhauser, H.N., and W.W. Baker. 1974. Annotated list of mammals of the coastal islands of Georgia. Pp. 197–209, In A.S. Johnson et al. (Eds.). An ecological survey of the Coastal Region of Georgia. United States National Park Service. Scientific Monograph Series No. 3. 233 pp. Rand, A.L., and P. Host. 1942. Results of the Archibold Expeditions. No. 45. Mammal notes from Highland County, Florida. Bulletin of the American Museum of Natural History 80:1–21. Stewart, D.T., T.B. Herman, and T. Teferi. 1989. Littoral feeding in a highdensity insular population of Sorex cinereus. Canadian Journal of Zoology 67:2074–2077. Whitaker, Jr., J.O. 1962. Endogone, Hymenogaster, and Melanogaster as small mammal foods. American Midland Naturalist 67:152–256. 366 Southeastern Naturalist Vol. 5, No. 2 Whitaker, Jr., J.O. 1988. Food habits analysis of insectivorous bats. Pp. 171–189, In T.H. Kunz (Ed.). Ecological and Behavioral Methods for the Study of Bats. Smithsonian Institution Press. Washington, DC. 533 pp. Whitaker, Jr., J.O., and W.W. Cudmore. 1987. Food and ectoparasites of shrews of south central Indiana with emphasis on Sorex fumeus and Sorex hoyi. Proceedings of the Indiana Academy of Science 96:543–553. Whitaker, Jr., J.O., and M.G. Ferraro. 1963. Summer food of 220 short-tailed shrews from Ithaca, New York. Journal of Mammalogy 44:419. Whitaker, Jr., J.O., and W.J. Hamilton, Jr. 1998. Mammals of the Eastern United States. Cornell University Press. Ithaca, NY, and London, UK. 583 pp. Whitaker, Jr., J.O., G.D. Hartman, and R. Hein. 1994. Food and ectoparasites of the southern short-tailed shrew, Blarina carolinensis (Mammalia: Soricidae), from South Carolina. Brimleyana 21:97–105. Whitaker, Jr., J.O., and R.E. Mumford. 1972. Food and ectoparasites of Indiana shrews. Journal of Mammalogy 53:329–335.