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Noxious Menu: Chemically Protected Insects in the Diet of Caracara cheriway (Northern Crested Caracara)
Joan L. Morrison, Jeffrey Abrams, Mark Deyrup, Thomas Eisner, and Michael McMillian

Southeastern Naturalist, Volume 6, Number 1 (2007): 1–14

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2007 SOUTHEASTERN NATURALIST 6(1):1–14 Noxious Menu: Chemically Protected Insects in the Diet of Caracara cheriway (Northern Crested Caracara) Joan L. Morrison1,*, Jeffrey Abrams1,2, Mark Deyrup3, Thomas Eisner4, and Michael McMillian5,6 Abstract - Analysis of regurgitated pellets of Caracara cheriway (Northern Crested Caracara) at a site in south-central Florida produced a wide variety of insects and spiders from 34 families and at least 72 genera. Species identified occur in dung, on carrion, and in both aquatic and terrestrial habitats. Some taxa identified are known to be chemically protected, and their consumption exposes Northern Crested Caracaras to a broad diversity of chemical deterrents: 1,4-benzoquinones, isoprenoids, carboxylic acids, esters, aldehydes, an alcohol, and ammonia, for example. Other species identified in pellets indicate that Northern Crested Caracaras likely experience other noxious substances, such as those produced by species with dischargeable defensive glands (i.e., formic acid), plant-derived deterrents ejected when the insects are disturbed, and venom produced by those that sting (i.e., piperidine alkaloids). Our collection of pellets represents only part of one year; therefore, the list of noxious chemicals ingested by these raptors with their insect food may be even more extensive than is now evident. Further analysis of more pellets and from both breeding season and non-breeding season months is warranted to obtain a more complete picture of this raptor’s insect diet. Introduction The Crested Caracara is a New World falcon of prairies and pastures. The southern species, Caracara plancus (J.F. Miller) (Southern Crested Caracara), is widespread throughout South America while C. cheriway (Jacquin) (Northern Crested Caracara, hereafter Caracara) occurs in parts of Mexico and Central America and, rarely, in southern North America. An isolated, threatened population of Caracaras occurs in central peninsular Florida (Morrison 1996). Caracaras feed on almost any kind of animal matter, dead or alive, including insects, reptiles, amphibians, small birds and mammals, carrion, and even aquatic animals in the shallows of drying seasonal wetlands (Morrison 1996, Morrison and Pias 2006). This raptor often forages on the ground, as described by Brown and Amadon (1968): “The long legs and 1Department of Biology, Trinity College, 300 Summit Street, Hartford, CT 06106. 2Current address - 128 Beechwood Road, Holden, MA 01520. 3Archbold Biological Station, PO Box 2057, Lake Placid, FL 33862. 4Cornell Institute for Research in Chemical Ecology, Department of Neurobiology and Behavior, W347 Seeley G. Mudd Hall, Cornell University, Ithaca, NY 14853. 5MacArthur Agro-Ecology Research Center, 300 Buck Island Ranch Road, Lake Placid, FL 33852. 6Current address - Florida Fish and Wildlife Conservation Commission, 1630 Royce Ranch Avenue, Lake Placid, FL 33852. *Corresponding author - 2 Southeastern Naturalist Vol. 6, No. 1 flat claws enable it to walk, run around, or scratch for food, almost with the facility of a chicken. It uses its feet to turn over branches or cakes of dried cow dung in search of beetles and to scratch like a hen. Or it will walk about picking up caterpillars. Again, at dusk, we have seen one proceeding very cautiously in water three or four inches deep, peering under leaves of floating plants, presumably in search of frogs. It comes to dead livestock with vultures, though when the carrion is very foul, it is perhaps chiefly interested in insects.” Like other falcons, Caracaras regurgitate indigestible prey remains in the form of pellets. These pellets often contain bits of insects enmeshed in a matrix of hair or plant matter. Our study deals with the insect fragments found by dissection of 200 pellets produced at one site in south-central Florida. Study Area and Methods Pellets were collected once each month during January through September 1999 (excluding May) from underneath two communal roosts at the MacArthur Agro-Ecology Research Center (MAERC, 27o10'N, 81o12'W), a division of Archbold Biological Station, near Lake Placid, FL. Currently, the landscape in south-central Florida is a mosaic of habitats that reflects complex patterns of land ownership and uses. Common habitats include large, open expanses of grasslands dotted with numerous shallow ponds, wetlands, and marshes and scattered or small clumps of Quercus virginiana P. Mill. (live oak), Sabal palmetto (Walt.) Lodd ex J.S. & J.H. Schultes (cabbage palm), Pinus spp. (pine), and Taxodium spp. (cypress). Principal land uses include cattle grazing, citrus, sugar cane, and other agricultural production. The primary land use at MAERC is cattle grazing on improved pasture and turf. Improved pastures are those in which native grasses have been removed and replaced with primarily exotic grasses that are intensively managed as forage for cattle. Improved pastures are generally laced with extensive networks of ditches and canals established for drainage. Each roost was a group of > 10 cabbage palms located in an improved pasture. The original roost found in January 1999 disbanded in late April; thus, no pellet collections were made in May. The second roost was also on MAERC, approximately 5 km east of the original roost. Pellet collections made in June through September were made at the second roost. Although numbers of Caracaras observed at the roosts ranged from 18 to 66 (n = 17 observation periods), accurate nightly counts are not available because individuals often returned to the roost after light was no longer adequate to count them. We also attempted to age individuals and noted individuals that were not in adult plumage; however, individuals often came in too quickly or in groups and after dark, and thus an accurate age distribution of roosting Caracaras during these observation periods could not be determined. At each sampling visit to collect pellets (n = 8), all pellets under the roost were collected; therefore, each collection represents approximately 1 month and an unknown number of individual Caracaras. 2007 J.L. Morrison, J. Abrams, M. Deyrup, T. Eisner, and M. McMillian 3 Pellets remained frozen after collection until they were analyzed. For analysis, twenty-five pellets were randomly chosen from each monthly sample (n = 8 months); broken or degraded pellets were excluded from analysis. Pellets were air dried then dissected using a 20x dissecting microscope. Insect fragments were identified to the lowest taxonomic level possible by matching wing covers, legs, head capsules, tergites, sternites, and mandibles with those of specimens in the extensive insect collection (over 30,000 specimens collected since the 1940s) at Archbold Biological Station. The quantity of insects represented in each pellet was recorded as the greatest number of individuals possible given the remnant fragments that are not replicated in an individual, such as the head capsule (used for ants), right wing cover (used for beetles) or right hind leg (used for grasshoppers). Results and Discussion Overall, 2868 insects and 78 spiders were found in the Caracara pellets (Appendix 1). These individuals represent 34 families and a minimum of 72 genera and are grouped by general adult habitat: dung, carrion, aquatic, and terrestrial (pasture) (Appendix 1). Most of these species disperse readily so individuals could also have been obtained as they were moving about. Many of the ground-dwelling species are frequently found under dried cow dung, where they may find a sheltered microhabitat. Unidentified species in the list (e.g., Ataenius sp.) represent fragments that could not be identified to species and might be the same as species already in the list (e.g., Ataenius fattigi) or one or more species not listed. Only the smallest insects such as Solenopsis invicta (fire ants) were sometimes intact. Soft-bodied prey, such as maggots or caterpillars, are probably underrepresented in our list. Based on the current sample, adult insect prey items tend to be larger than 4 mm in length. There are no species with highly developed capabilities for evasive flight, characteristic of most adult Odonata, Hymenoptera, Lepidoptera, and Diptera. Jumping Orthoptera are well represented (Appendix 1). Most insect prey are native species, but the best represented scarab beetle, Onthophagus gazella, was introduced from Africa (Peck and Thomas 1998). Chemical defenses of ingested insects Of the insect species positively identified from the Caracara pellets, a number are from taxa known to be chemically protected. Five species of this group produce defensive secretions of known composition, so it is possible to list with certainty at least some of the noxious chemicals to which Caracaras are exposed. These five insects—two carabid beetles (Attygalle et al. 1991, McCullough 1966), a silphid beetle (Eisner and Meinwald 1982, Eisner et al. 1986), a staphylinid beetle (Jefson et al. 1983), and an earwig (Eisner et al. 2000)—are listed in Table 1, together with their known defensive products, designated by numbers 1 to 23 (Table 1, Fig. 1). Clearly, consumption of just these five species would in itself suffice to expose Caracaras to a broad 4 Southeastern Naturalist Vol. 6, No. 1 diversity of chemical deterrents, including 1,4-benzoquinones, isoprenoids, carboxylic acids, esters, aldehydes, and alcohols. Of the other species on the list, a number belong to groups also known to possess dischargeable defensive glands. Although these species have not themselves been studied chemically, their chemistry can be inferred from what is known about their close relatives. Thus, we are inclined to add formic acid (24) to the list of chemicals “experienced” by Caracaras. Formic acid is a ubiquitous component of the defensive spray of formicine ants (Hölldobler and Wilson 1990), and it is almost certainly produced by Camponotus floridanus, itself a member of the Formicinae. In fact, we have worked with C. floridanus (Eisner et al. 1993) and found this ant, when disturbed, to emit an odor unmistakably recognizable as formic acid. Caracaras may also ingest formic acid when they consume Agonum extensicolle, a carabid beetle whose congeners have been shown to produce formic acid as Table 1. Insects found in Northern Crested Caracara pellets whose secretion is known chemically. Compound numbers correspond to structures in Figure 1: 1) isobutyric acid; 2) methacryclic acid; 3) isocrotonic acid; 4) crotonic acid; 5) angelic acid; 6) tiglic acid; 7) salicylaldehyde; 8) caprylic acid; 9) capric acid; 10) (E)-3- Decenoic acid; 11) (E)-4-decenoic acid; 12) lavandulol; 13) 􀁟-necrodol; 14) 􀁠- necrodol; 15) isoamyl alcohol; 16) isoamyl acetate; 17) iridodial; 18) actinidine; 19) dihydronepetalactone; 20) (E)-8-oxocitronellyl acetate; 21) 2-methyl-1,4-benzoquinone; 22) 2,3-dimethyl-1,4-benzoquinone; 23) pentadecane. Compound(s) present in Insect defensive secretion Coleoptera Carabidae Scarites subterraneus 1–6 Calosoma sayi 7 Silphidae Necrodes surinamensis 8–14 Staphylinidae Creophilus maxillosus 15–20 Dermaptera Forficulidae Doru taeniatum 21–23 Figure 1 (facing page). Defensive products from insects. Structures 1–23 are from secretions of species identified from our pellet samples (Table 1). Structures 24–29 are from close relatives of insects found in the pellets and therefore assumed to be produced by the latter species as well. These include 24) formic acid; 25) ammonia; 26) (E)-2-hexenal; 27) desoxycorticosterone; 28) 2-ethyl-1,4-benzoquinone; and 29) 2- methyl-6-undecylpiperidine. Compounds 21 and 22, produced by D. taeniatum (one of the species in Table 1), are also widely present in tenebrionid secretions. Compound 29, from S. invicta (an ant present in the pellets), is a toxic product of the venom of the ant and therefore of potential danger to Northen Crested Caracaras should these birds be stung by the ant. 2007 J.L. Morrison, J. Abrams, M. Deyrup, T. Eisner, and M. McMillian 5 part of their spray (Schildknecht et al. 1968). Additional insect defensive agents likely to be ingested by Caracaras are: ammonia (25) present in the defensive effluent of silphid beetles (Schildknecht 1970); aliphatic aldehydes (for instance, E-2-hexenal [26]) and their hydrocarbon solvents, such 6 Southeastern Naturalist Vol. 6, No. 1 as are commonly discharged by pentatomid Hemiptera (Aldrich 1988); steroids (including desoxycorticosterone [27] or similar pregnanes) known from the defensive glands of belostomatid Hemiptera (Lokensgard et al. 1993); and 1,4-benzoquinones (21, 22, 28), such as are commonly produced by tenebrionids (Tschinkel 1975). Some of the compounds listed in Table 1 may also enter the Caracara diet by way of additional insect sources. The carboxylic acids 1, 2, 5, and 6, for instance, which Caracaras ingest with Scarites subterraneous, could also be taken in by the birds with Pachymachus that they eat (e.g., P. punctulatus, P. sublaevis), given that these compounds are known to be secreted by another species of the genus (P. subsulcatus; Davidson et al. 1989). The list of noxious chemicals ingested by Caracaras with their insect food is likely more extensive than is now evident. Some insects found in the pellets belong to groups known to be chemically protected, but their specific chemical products have yet to be characterized. There is evidence, for instance, that some scarabs have glandular defenses (Eisner et al. 2005b), but their secretions have not been analyzed. By the same token, the cercopid Prosapia bicincta reflex-bleeds from the legs when disturbed, but nothing is known about the chemistry of its blood (Eisner et al. 2005b, Peck 2000). By feeding on grasshoppers, Caracaras are also exposed to plant-derived deterrents ejected by grasshoppers with the regurgitant they emit when disturbed (Eisner 1970, Sword 2001). Species of Melanoplus and Schistocerca, for instance, are known to vomit when attacked and, given their polyphagous habits, are bound at times to be carriers of noxious enteric chemicals. The ingestion of ants that sting could also be potentially hazardous to Caracaras. Both Solenopsis invicta and the Odontomachus species found in the pellets have a capability to sting (Hölldobler and Wilson 1990). Ant venoms are chemically complex, and their mode of action is often not fully understood. In the case of S. invicta, the pain one feels after being stung by this ant is due in part to the presence of piperidine alkaloids in the venom (e.g., 29 in Fig. 1), which act by inducing the release of histamine from mast cells (Leclercq et al. 2000). Whether Caracaras manage somehow not to get stung when they ingest these ants is open to question. Caracaras at our Florida site probably have a limited interest in S. invicta and possibly ingest this species incidentally with carrion. Sites throughout south-central Florida where these birds occur are dotted with the conspicuous mounds of S. invicta, whose workers are ready to rush out in large numbers at any disturbance. Given this ant’s broad distribution and availability, if it were a favored food item, it should occur in much larger numbers in pellets. Caracaras are evidently able to tolerate a diversity of noxious chemicals from the armamentarium of insects. Some of these compounds, such as the carboxylic acids, including the structurally “simplest” of these, formic acid, are potent irritants that one might expect to be deterrent to birds. Ingestion of Pasimachus, Agonum, and Camponotus species by Caracaras would therefore not necessarily have been predicted. Other birds, however, are known to 2007 J.L. Morrison, J. Abrams, M. Deyrup, T. Eisner, and M. McMillian 7 feed on formic acid-producing insects, notably on ants, by the behavior “anting,” a pre-ingestive procedure by which the ants are seized in the bill by the bird and wiped into the plumage, thereby being forced to expel their secretory reserves and being rendered tasty (Eisner et al. 2005a, Judson and Bennet 1990). Caracaras are not known to engage in anting (the behavior appears to be restricted to passerine birds), but they could conceivably have alternative ways of avoiding full exposure to their prey’s defenses. Also surprising was that the pellets contained remnants of pentatomids as well as of cydnids, which share with pentatomids the possession of “stink” glands and produce the same sort of defensive substances as pentatomids (Aldrich 1988). Pentatomids are assumed to be protected by their glands, but their protection is evidently not absolute, at least not vis à vis some non-avian predators (Aldrich 1988, Eisner 2003) and perhaps including Caracaras. One beetle encountered in the pellets, the silphid Necrodes surinamensis, was shown, in laboratory tests with mealworms as controls, to be unacceptable to Catharus ustulatus (Nuttall) (Swainson’s Thrush) (Eisner and Meinwald 1982). Similarly, data with a carabid beetle of the genus Calosoma (not C. sayi itself, but another salicylaldehyde-producing species) indicate that such beetles may be unacceptable to Cyanocitta cristata (Linnaeus) (Blue Jays) (Eisner et al. 1963). Although not nearly enough is known about the antiavian effectiveness of insect defensive compounds, Caracaras seem to be constituted to withstand a formidable array of such substances. Some of the chemicals presumably ingested by Caracaras with insects could conceivably induce delayed effects upon the birds. For example, pregnane steroids, such as those that Caracaras may ingest with belostomatids, could have a sedative effect on the birds similar to that which they are known to have on other vertebrates (Miller and Mumma 1976). The consumption of silphid beetles by Caracaras is of special interest. These large, somewhat clumsy beetles are found dependably at carcasses. This predictable aggregation makes them vulnerable to predators and may have led to the evolution of powerful deterrent chemicals, advertised by warning coloration. Caracaras, as insectivores that also feed on carrion, must have had a long-term association with silphids, and may therefore have developed a degree of tolerance to the beetles’ protective substances. As our collection of pellets represents only part of one year, further analysis of more pellets and from both breeding season and non-breeding season months is warranted to obtain a complete picture of this raptor’s insect diet. In addition, Caracaras range broadly from Florida, through parts of Texas, Arizona, and Central America and throughout South America. It would be interesting to know whether the bird adheres, throughout its range, to its Floridian habit of ingesting chemically protected insects. Acknowledgments We thank S. McGehee for assistance with collecting pellets in the field, and K. Pias and L. Wang for assistance with dissecting pellets. Funding was provided by a 8 Southeastern Naturalist Vol. 6, No. 1 Faculty Research Grant from Trinity College (to J.L. Morrison), an internship to J. Abrams from the Archbold Biological Station, and grant number AI02908 from the National Institutes of Health to T. Eisner. This paper is contribution #93 from the MacArthur Agro-Ecology Research Center of the Archbold Biological Station. Literature Cited Aldrich, J.R. 1988. Chemical ecology of the Heteroptera. Annual Review of Entomology 33:211–238. Attygalle, A.B., J. Meinwald, and T. Eisner. 1991. Biosynthesis of methacrylic and isobutyric acids in a carabid beetle, Scarites subterraneus. Tetrahedron Letters 32:4849–4852. Brown, L., and D. Amadon. 1968. Eagles, Hawks, and Falcons of the World. McGraw-Hill Book Co., New York, NY. 945 pp. Davidson, B.S., T. Eisner, B.W. Witz, and J. Meinwald. 1989. Defensive secretion of the carabid beetle Pasimachus subsulcatus. Journal of Chemical Ecology 15:1689–1697. Downie, N.M., and R.H. Arnett, Jr. 1996. The Beetles of Northeastern North America. The Sandhill Crane Press, Gainesville, FL. 1721 pp. Eisner, T. 1970. Chemical defenses against predation in arthropods. Pp.. 157–218, In E. Sondheimer and J. B. Simeone (Ed.). Chemical Ecology. Academic Press, New York, NY. 336 pp. Eisner, T. 2003. For Love of Insects. Harvard University Press, Cambridge, MA. 449 pp. Eisner, T., and J. Meinwald. 1982. Defensive spray mechanism of a silphid beetle (Necrodes surinamensis). Psyche 89:357–367. Eisner, T., C. Swithenbank, and J. Meinwald. 1963. Defense mechanisms of arthropods. VIII. Secretion of salicylaldehyde by a carabid beetle. Annals of the Entomological Society of America 56:37–41. Eisner, T., M. Deyrup, R. Jacobs, and J. Meinwald. 1986. Necrodols: Anti-insectan terpenes from defensive secretion of carrion beetle (Necrodes surinamensis). Journal of Chemical Ecology 12:1407–1415. Eisner, T., I.T. Baldwin, and J. Conner. 1993. Circumvention of prey defense by a predator: Ant lion vs. ant. Proceedings of the National Academy of Sciences USA 90:6716–6720. Eisner, T., C. Rossini, and M. Eisner. 2000. Chemical defense of an earwig (Doru taeniatum). Chemoecology 10:81–87. Eisner, T., M. Eisner, and D. Aneshansley. 2005a. Pre-ingestive treatment of bombardier beetles by jays: Food preparation by “anting” and “sand-wiping.” Chemoecology 15:227–233. Eisner, T., M. Eisner, and M. Siegler. 2005b. Secret Weapons. Harvard University Press, Cambridge, MA. 332 pp. Hölldobler, B., and E.O. Wilson.1990. The Ants. Harvard University Press, Cambridge, MA. 732 pp. Jefson, M., J. Meinwald, S. Nowicki, K. Hicks, and T. Eisner. 1983. Chemical defense of a rove beetle (Creophilus maxillosus). Journal of Chemical Ecology 9:159–180. Judson, O.B., and T.D. Bennett. 1990. Anting as food preparation: Formic acid is worse on an empty stomach. Behavioral Ecology and Sociobiology 31:437–439. 2007 J.L. Morrison, J. Abrams, M. Deyrup, T. Eisner, and M. McMillian 9 Leclercq, S., J.C. Braekman, J.C. Daloze, and J.M. Pasteels. 2000. The defensive chemistry of ants. Progress in the Chemistry of Organic Natural Products 79:115–129. Lokensgard, J., R. Smith, T. Eisner, and J. Meinwald. 1993. Pregnanes from defensive glands of a belostomatid bug. Experientia 49:175–176. McCullough, T. 1966. Quantitative determination of salicylaldehyde in the scent fluid of Calosoma macrum, C. alternans sayi, C. affine, and C. parvicollis (Coleoptera: Carabidae). Annals of the Entomological Society of America 59:1018. Miller, J.R., and R.O. Mumma. 1976. Physiological activity of water beetle defensive agents. I. Toxicity and anesthetic of steroids and norsesquiterpenes administered in solution to the minnow Pimephales promelas Raf. Journal of Chemical Ecology 2:115–130. Morrison, J.L. 1996. Crested Caracara. Birds of North America 249:1–28. Morrison, J.L., and K.E. Pias. 2006. Assessing the vertebrate component of the diet of Florida’s crested caracaras (Caracara cheriway). Florida Scientist 69:36–43. Peck, D.C. 2000. Reflex bleeding in froghoppers (Homoptera: Cercopidae): Variation in behavior and taxonomic distribution. Annals of the Entomological Society of America 93:1186–1194. Peck, S.B., and M.C. Thomas. 1998. A distributional checklist of the beetles (Coleoptera) of Florida. Arthropods of Florida and Neighboring Land Areas 16:1–180. Schildknecht, H. 1970. The defensive chemistry of land and water beetles. Angewandte Chemie 9:1–9. Schildknecht, H., U. Maschwitz, and H. Winkler. 1968. Zur Evolution der Carabiden-wehrdrüsensekrete. Naturwissenschaften 55:112–117. Sword, G.A. 2001. Tasty on the outside, but toxic in the middle: Grasshopper regurgitation and host plant-mediated toxicity to a vertebrate predator. Oecologia 128:416–421. Tschinkel W.R. 1975. A comparative study of the chemical defensive system of tenebrionid beetles: Chemistry of the secretions. Journal of Insect Physiology 21:753–784. Woodruff, R.E. 1973. The scarab beetles of Florida. (Coleoptera: Scarabaeidae). Part I. The Laparosticti (Subfamilies: Scarabaeinae, Aphodiinae, Hybosorinae, Ochodaeinae, Geotrupinae, Acanthocerinae). Arthropods of Florida and Neighboring Land Areas 8:1–220. 10 Southeastern Naturalist Vol. 6, No. 1 Appendix 1. Numbers of individual insects and spiders found in pellets of the Northern Crested Caracara collected at two communal roosts on the MacArthur Agro-Ecology Research Center, Lake Placid, FL, January through September (excluding May), 1999. Proportion of Proportion appearance Ecological niche Order Family Species Number in diet in pellets Dung insects1 Coleoptera Scarabaeidae Onthophagus gazella Fabricius 573 12.6 36.0 O. hecate blatchleyi Brown 152 3.4 39.0 Aphodius pseudolividus Balthasar 19 0.4 4.0 A. floridanus Robinson 16 0.4 6.0 A. campestris Blatchley 3 0.1 1.5 A. nigritus (Fabricius) 1 < 0.1 0.5 Phaenius vindex MacLeay 6 0.1 3.0 Boreocanthon depressipennis (LeConte) 3 0.1 1.5 B. probus (Germar) 1 < 0.1 0.5 Carrion insects2 Coleoptera Silphidae Necrodes surinamensis Fabricius 114 2.5 21.5 Oiceoptoma inaequale (Fabricius) 4 0.1 0.5 Nicrophorus carolinus (Linneus) 4 0.1 1.0 Nicrophorus sp. 7 0.2 3.5 Silphid larva 1 < 0.1 0.5 Histeridae Euspilotus assimilis (Paykull) 78 1.7 15.0 Hister abbreviatus Fabricius 79 1.7 20.5 Saprinus pennsylvanicus Paykull 6 0.1 2.5 Trogidae Omorgus sp. 20 0.4 13.0 Trox sp. 1 < 0.1 1.0 Staphylinidae Creophilus maxillosus (Linneus) 2 < 0.1 0.5 Cleridae Necrobia rufipes Degeer 5 0.1 2.5 Nitidulidae Nitidula ziczac Say 2 < 0.1 1.0 Dermestidae Dermestes sp. (adults) 157 3.5 30.0 Dermestes sp. (larvae) 3 0.1 1.0 2007 J.L. Morrison, J. Abrams, M. Deyrup, T. Eisner, and M. McMillian 11 Proportion of Proportion appearance Ecological niche Order Family Species Number in diet in pellets Diptera Stratiomyidae Hermetia sp. (larvae and pupae) 48 0.2 1.5 Aquatic insects Coleoptera Hydrophilidae Enochrus fimbriatus (Melsheimer) 1 < 0.1 0.5 E. perplexus (LeConte) 4 0.1 1.5 Enochrus sp. 2 < 0.1 0.5 Tropisternus mexicanus Laporte 3 0.1 1.5 T. lateralis nimbatus (Say) 1 < 0.1 1.0 Hydrochus rugosus Mulsant 1 < 0.1 0.5 Noteridae Hydrocanthus regius Young 1 < 0.1 0.5 Heteroptera Corixidae Unidentified genus 2 < 0.1 1 Belostomatidae Belostoma sp. 7 0.2 3.0 Lethocerus griseus (Say) 1 < 0.1 0.5 Ground-dwelling Coleoptera Scarabaeidae Dyscinetus morator (Fabricius) 176 3.9 32.0 pasture insects Euetheola humilis rugiceps (LeConte) 177 3.9 29.0 and spiders D. morator or E. humilis 80 1.8 12.5 Euphoria sepulchralis (Fabricius) 4 0.1 2.0 Anomala marginata (Fabricius) 1 < 0.1 0.5 Ataenius alternatus (Melsheimer) 9 0.2 4.0 A. fattigi Cartwright 20 0.4 5.5 Ataenius sp. 19 0.4 5.0 Cotinus nitida (Linneus) 9 0.2 4.5 Phyllophaga latifrons (LeConte) 24 0.5 1.5 Phyllophaga sp. 2 < 0.1 1.0 Diplotaxis bidentata LeConte 1 < 0.1 0.5 Carabidae Scarites quadriceps Chaudoir 4 < 0.1 1.0 S. subterraneus Fabricius 12 0.3 6.0 Pasimachus punctulatus Haldeman 1 < 0.1 0.5 12 Southeastern Naturalist Vol. 6, No. 1 Proportion of Proportion appearance Ecological niche Order Family Species Number in diet in pellets Ground-dwelling Coleoptera Carabidae P. sublaevis (Palisot de Beauvois) 2 < 0.1 1.0 pasture insects Amblygnathus sp. 2 < 0.1 1.0 and spiders Calosoma sayi Dejean 11 0.2 5.5 Agonum extensicolle (Say) 1 < 0.1 0.5 Cyclotrachelus faber (Germar) 14 0.3 1.0 Cyclotrachelus sp. 2 < 0.1 1.0 Selenophorus palliatus 1 < 0.1 0.5 Megacephala virginica (Linneus) 3 0.1 1.5 Carabidae Unidentified genera 10 0.2 5.0 Curculionidae Pachnaeus litus (Germar) 50 1.1 17.5 Sphenophorus venatus vestitus Chittenden 70 1.5 19.0 S. necydaloides (Fabricius) 7 0.2 2.5 S. cariosus (Olivier) 2 < 0.1 1.0 S. inaequalis (Say) 1 < 0.1 0.5 S. chittendeni Blatchley 1 < 0.1 0.5 Sphenophorus sp. 12 0.3 4.0 Curculionidae Unidentified genus 1 < 0.1 0.5 Elateridae Blauta cribraria (Germar) 3 0.1 1.5 Neotrichophorus carolinensis Schaeffer 1 < 0.1 0.5 Heteroderes amplicollis (Gyllenhal) 3 0.1 1.0 Conoderus bellus (Say) 1 < 0.1 0.5 Melanotus americanus Herbst 5 0.1 1.0 Elateridae Unidentified genus 8 0.2 4.0 Histeridae Phelister subrotundus Say 1 < 0.1 0.5 Hydrophilidae Phaenonotum minor Smetana 1 < 0.1 0.5 2007 J.L. Morrison, J. Abrams, M. Deyrup, T. Eisner, and M. McMillian 13 Proportion of Proportion appearance Ecological niche Order Family Species Number in diet in pellets Coleoptera Tenebrionidae Opatrinus minimus (Palisot de Beauvois) 36 0.8 13.0 Lobopoda erythrocnemis Germar 2 < 0.1 1.0 Bothrotes canaliculatus acutus (LeConte) 3 0.1 1.0 Poecilocrypticus formicophilus Gebien 1 < 0.1 0.5 Gondwanocrypticus sp. 2 < 0.1 0.5 Allobates pennsylvanicus (Degeer) 1 < 0.1 0.5 Hybosoridae Hybosorus illigeri (Reiche) 1 < 0.1 0.5 Heteroptera Pentatomidae Acrosternum pennsylvanicum (Gmelin) 1 < 0.1 0.5 Andrallus spinidens (Fabricius) 1 < 0.1 0.5 Euschistus sp. 1 < 0.1 0.5 Cydnidae Cyrtomenus ciliatus (Palisot de Beauvois) 1 < 0.1 0.5 Homoptera Cercopidae Prosapia bicincta (Say) 1 < 0.1 0.5 Dermaptera Forficulidae Doru taeniatum (Dohrn) 2 < 0.1 1.0 Labiduridae Labidura riparia (Pallus) 40 0.9 8.0 Carcinophoridae Anisolabis maritima Gene 1 < 0.1 0.5 Euborellia annulipes (Lucas) 64 1.4 14.5 Labiidae Vostox brunneipennis (Serville) 13 0.3 4.0 Dermaptera Unidentified genus 2 < 0.1 1.0 Orthoptera Acrididae Melanoplus sp. or Paroxya sp. 6 0.1 2.0 Schistocerca americana (Drury) 1 < 0.1 0.5 Schistocerca sp. 1 < 0.1 0.5 Acrididae Unidentified genus (primarily legs, head 53 1.2 23.0 capsules of immatures) Gryllidae Gryllus assimilis (Fabricius) 4 0.1 0.5 Gryllidae Unidentified genus 18 0.4 6.0 Gryllotalpidae Scapteriscus vicinus Scudder 5 0.1 2.5 Neocurtilla hexadactyla (Pertt) 1 0.1 2.0 14 Southeastern Naturalist Vol. 6, No. 1 Proportion of Proportion appearance Ecological niche Order Family Species Number in diet in pellets Ground-dwelling Orthoptera Gryllotalpidae Unidentified genus 33 0.7 1.6 pasture insects Tettigoniidae Neoconocephalus triops (Linnaeus) 1 < 0.1 0.5 and spiders Tetrigidae Paratettix mexicanus (Saussure) 1 < 0.1 0.5 Hymenoptera Formicidae Solenopsis invicta Buren 453 9.9 6.5 Camponotus floridanus (Buckley) 1 < 0.1 1.0 Odontomachus sp. 2 < 0.1 1.0 Araneida Lycosidae Unidentified genus 76 1.7 29.0 Gnaphosidae Unidentified genus 1 < 0.1 0.5 Salticidae Unidentified genus 1 < 0.1 0.5 Total 2946 100 1Our association of these beetles with dung is derived from information on collection labels in the Archbold insect collection and from Woodruff (1973). 2Our association of these beetles with carrion is derived from information on labels in the Archbold insect collection and from Downie and Arnett (1996) and Peck and Thomas (1998).