Western North American Naturalist

Volume 63 Number 3 Article 16

8-6-2003

Fall diet of Chukars (Alectoris chukar) in eastern Oregon and discovery of ingested lead pellets

Hanspeter Walter California Department of Water Resources, Sacramento, California

Kerry P. Reese University of Idaho, Moscow

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Recommended Citation Walter, Hanspeter and Reese, Kerry P. (2003) "Fall diet of Chukars (Alectoris chukar) in eastern Oregon and discovery of ingested lead pellets," Western North American Naturalist: Vol. 63 : No. 3 , Article 16. Available at: https://scholarsarchive.byu.edu/wnan/vol63/iss3/16

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FALL DIET OF CHUKARS (ALECTORIS CHUKAR) IN EASTERN OREGON AND DISCOVERY OF INGESTED LEAD PELLETS

Hanspeter \\Talter1 and Kerry P. Reese2

Key words: Alectoris chukar, Bromus tectorum, cheatgrass, Chukar, crops, diet, lead shot, Lithophragma parviflOlum, Oregon, prairie starflower.

Chukars were widely introduced into the steppe community dominated by the Wyoming United States in the early WOOs and have big sagebrush (Artemisia tridentata wyomin­ thrived in the arid Intermountain \Vest. gensis) / bluebunch wheatgrass (Agropyron spi­ Numerous investigations occurred during catum) habitat type (Hironaka et al. 1983). their introduction and establishment, but few Annual precipitation in the area averaged 23.8 field studies have examined this species in em during 1995-1998 (National Oceanic and North America during the last 35 years. Chukar Atmospheric Administration 1998). food habits were reported from Nevada (Alcorn Crops and gizzards of harvested Chukars and Richardson 1951, Christensen 1952, 1996, were opportunistically collected from hunters Weaver and Haskell 1967), Washington (Gal­ in the field from October to January during breath and Moreland 1953), California (Harper the 1995-1998 hunting seasons and frozen. et al. 1958, Zembal 1977), Colorado (Sandfort These were later thawed and their contents 1954), and Hawaii (Cole et al. 1995), but never separated into component items. We carefully from Oregon despite an average annual har­ examined crops and gizzards for entry wounds vest of 86,872 during 1990-1996, the highest to differentiate ingested lead pellets from those among upland game birds in the state (Oregon shot into the organs. Crop items were dried at Department of Fish and Wildlife 1998). Earlier 60°C for 24 hours and weighed to the nearest diet reports were investigations of small, local­ 0.01 g with an electronic scale. To assure that ized samples from throughout the West and drying temperature and duration were suffi­ consequently may not reflect current Chukar cient to render all weights constant, we evalu­ diets in eastern Oregon. Changes in composi­ ated the procedures with a subsample ofcrops. tion of plant communities in western range­ Crop items were identified to the lowest lands over the past decades, particularly the practical taxonomic level using reference sam­ impact of exotic species (Franklin et al. 1999) ples collected from the study area and a seed and fire (Whisenant 1990), reinforce the need manual (Martin and Barkley 1961). We recorded for regionally specific and timely diet informa­ the number of distinct food items and their tion. Our objectives are to report the fall diet dry weight for each crop, excluding empty of Chukars in eastern Oregon and compare crops from analysis. We calculated frequency results to previous studies. of occurrence of crop items for the total sam­ The study area was Succor Creek State Park ple and reported standard deviation and range and surrounding lands in the Vale District of when applicable. Contribution of each item is the Bureau of Land Management (BLM) in expressed using aggregate weight (Litvaitus et Malheur County, southeastern Oregon. Private­ al. 1994). Items occurring in <3.0% ofcrops or ly owned irrigated pasture occupies a small contributing <3.0% of aggregate dry weight portion of the area. Typical of Chukar habitat were excluded fi'om analysis. Although there in Oregon, there are many canyons, steep was annual variation, samples from all years slopes, and loose rock with elevations ranging were combined to form a single aggregate sam­ from 600 m to 1700 m. Vegetation is a shrub- ple describing general fall diet. This facilitated

ICaljfornia Department of\\'ater Resources, 3251 ·S~ Street, Sacramento. CA 95816-7017. 2Department of Fish and Wildlife Resources. University of Idaho. Box 441136, Moscow, ID 83844·1136.

402 2003] NOTES 403 comparisons with past studies. A discussion of other kinds of seed was 7.4%, 18 other plant possible causes ofannual diet variation includ­ parts 1.8%, and 10 unidentified items 0.1%. ing climate and habitat use is presented in Many of our findings were similar to those Walter (2000). of past studies. Cheatgrass seeds and leaves We found 72 different items in crops from were also the predominant food items found fall 1995 (n = 10), 1996 (n = 66), 1997 (n = 36), in other studies (Alcorn and Richardson 1951, and 1998 (n = 28). Number of different items Christensen 1952, 1970, 1996, Weaver and per crop averaged 4.8 (s = 2.6, range = 1-12 Haskell 1967, Zembal 1977). Other seeds of items, n = 140). Mean weight ofcrop contents importance to Chukars in eastern Oregon after drying was 2.51 g (s = 2.5, range = such as filaree (Erodium spp.), and insects 0.01-10.93 g, n = 140). such as grasshoppers and ants, also have been Eighteen distinct items occurred in more documented (Alcorn and Richardson 1951, than 3.0% of the crops (Table 1). Cheatgrass Christensen 1952, Weaver and Haskell 1967). seeds were the most frequently encountered Seventy-two items were identified from crops item, occurring in 87.5% ofcrops, while leaves in our study, but only 6 contributed 82.2% of and shoots of grasses, predominantly cheat­ the total dry weight. Previous studies also grass, were in 58.6% ofthe sample. The subter­ indicated that Chukars rely on relatively few ranean bulbils ofprairie starflower occurred in foods for the bulk of their fall diet. Only 13 of 46.4% of the sample. Twenty other kinds of 55 items were major components ofthe Chukar seeds occurred in 41.3% of crops and 18 other diet in California (Zembal 1977), and of22 dif­ plant parts occurred in 15.7% of crops, collec­ ferent plant genera found in crops from tively. Ten unidentified items occurred in 7.3% Nevada, only 5 comprised over 72% of the total volume (Weaver and Haskell 1967). Our ofcrops. Arthropods were found in 26.4% of crops. data also suggest Chukars are opportunistic feeders that consume a wide variety of foods Grasshoppers (Orthoptera) were the most ccm­ but heavily rely on only a small subset in a mon, but others included ants (Hymenoptera), particular region. This exploratory foraging bugs (Hemiptera), and spiders (Arachnidae). nature may have facilitated establishment and Sagebrush (Artemisia spp.) leaves were found range expansion in North America by enabling in 5.7% of crops, but galls, which are charac­ Chukars to rapidly sample and identifY suit­ teristic of sagebrush parasitization gall by able foods in new areas. midges (Jones 1971), were found in 26.4% of Subterranean bulbils of prairie starflower crops. contributed most to the dry weight of our OUf most startling discovery was ingested sample and ranked 4th in frequency, but they shot pellets in 7.1% of 140 non-empty crops. were less significant in previous studies. The The mean number ofingested lead pellets was bulbils, which function as asexual reproductive 1.7 (s = 0.5, range = 1-2 pellets, n = 8) and 2 structures (Taylor 1965), occurred in 42.7% of crops had 1 and 3 steel pellets, respectively. fall crops collected in Washington but con­ Investigation of 123 gizzards also revealed in­ tributed only 4.6% to wet volume (Knight et gested lead pellets in 7 (5.7%). Unfortunately, a!. 1979). They also OCCUlTed in 35.0% ofcrops our collection of samples from sportsmen in from central Nevada, contributing 8.3% to wet the field precluded identification of crops and volume (Weaver and Haskell 1967). The high gizzards from the same bird. contribution to aggregate weight of bulbils in Drying and weighing of the sample indi­ our sample may be due to the fact that they cated that of the 18 most frequent cUet items, were denser than other food items and lost an even smaller subset contributed the great­ less weight when dried, a factor not accounted est amount to dry weight (Table 1). The sub­ for in the previous wet volume analyses. It terranean bulbils of prairie starflower com­ may also be due to the large quantity of bul­ prised 29.5% of dry weight of the sample and bils found in individual crops. Crops full of cheatgrass seeds 24.9%. Boragiuaceae spp. bulbils added significantly more to aggregate seeds accounted for 12.6% of dry weight, with weight than tl,ose containing few bulbils, but other items including grass leaves (7.2%), sage­ frequency of occurrence remained the same. brush galls (4.2%), arthropods (3.9%), and grit Bulbils appear to be an important fall food (1.6%). The contribution to dry weight of 25 item where available in eastern Oregon. 404 WESTERN NORTH AMERICAN NATURALIST [Volume 63

TABLE L Items found in Chukar crops from eastern Oregon during fall, 1995-1998.

Frequency 01)' weight Crop itema Scientific name (%) (%) Years foundb Cheatgrass seeds Bromus tectorom 87.5 24.9 95,96,97,98 Crass leaves Various 58.6 7.2 96,97,98 Grit n/a SO.O 1.6 95,96,97,98 5tarf]ower bulbils Lithophragma parviflonlt11 48.4 29.5 95,96,97,98 Borage seeds Boraginaceae spp. 31.4 12.6 95,96,97,98 Sagebrush galls Artemisia spp. 26.4 4.2 96,97,98 Filaree seeds Erodium spp. 26.4 1.5 95,96,97,98 Arthropods Arthropoda spp. 26.' 3.9 96,97,98 Spiny lettuce Lactuca scarioln 22.9 1.0 96,97,98 Hawksbeard Crepis acuminata 8.5 1.0 96,97 Sunflower Helianthus annus 6.4 1.0 96,97 Sagebrush leaves Artemisia spp. 5.7 < 0.1 96,97,98 Bluebunch wheatgrass seeds Agropyron spicatum 5.0 0.3 96,97 Shot pellets n/. 4.9 0.5 96,97,98 Spiny greenbush Clossopetakm nevadense 4.3 0.4 95,96,97,98 Feathers n/. 4.3 < 0.1 96,97 Broomrape Orobanche sp. 3.6 0.7 97,98 Idaho fescue seeds Festuca idahoensis 3.6 0.5 95,96 Othe' seeds (20) n/. 41.3 7.4 95,96,97,98 Other plants (18) n/. 15.7 1.8 95,96,97,98 Unidentified (10) n/. 7.3 0.1 96,97,98 aonly items occurring in >3.0% orsample or contributing >3.0% to dry weight of the sample are listed. bl995 (II = 10), 1996 (II = 66), 1997 (II = 36), 1998 (II = 28).

Because they must be uprooted from below­ colchicus; Hunter and Rosen 1965), and Wild ground, we do not suspect bulbils are as read­ Turkey (Me/eagris gallopavo; Stone and Butkas ily available or ingested when the ground is 1972). This discovery rep,esents what may frozen or covered in heavy snow. occur in Chukars during seasons ofheavy hunt­ It appears fall food requirements ofChukars ing pressure in areas where conditions favor­ in eastern Oregon will be mel provided annual able to shot pellet ingestion are p,esent. The grasses, especially cheatgrass, are available. arid climate and presence of rocky benches Heterogeneity of vegetation, however, is rec­ may leave pellets exposed for long periods, ommended due to the ingestion ofmany other increasing their chance of random ingestion food items and likely diet variation among sea­ by Chukars who mistake them for seeds or sons and age groups. Cheatgrass is not favored grit. Rocky areas are heavily used by Chukars by other rangeland birds (Goebel and Berry (Lindbloom 1998, Walter 2000) and are often 1976), and its high level of consumption by where hunters focus activity. Concentrated Chukars suggests that there is not strong com­ hunting pressure in crop fields was reported petition between Chukars and native birds for to increase chances of lead shot ingestion by food. Because the success of the Chukar in Mourning Doves (Zenaida macroura) favoring Torth America appears linked to cheatgrass, those fields (Le\vis and Legler 1968), and a this is an interesting case ofone exotic species similar phenomenon may have occurred in facilitating the establishment of another (Sim­ our study. berloff and Von Holle 1999). Additional stud­ While the hazards oflead shot are well doc­ ies should investigate food preferences and umented for waterfowl and birds of prey, they causes ofannual variation in Chukar diets. are less known in other species; however, risk Ingested shot pellets have never been re­ oflead shot to upland birds is becoming increas­ ported in Chukars, although they have been ingly apparent and acknowledged as a potential found in other Gallifonnes such as Northern management concern (Locke and Bagley 1967, Bobwhite (Colinus virginianus; Westminster Kendall et aJ. 1996). Our findings are site spe­ 1966), Scaled Quail (Callipepla squamnta; Camp­ Cific, but the possibility that lead ingestion may bell 1950), Ring-necked Pheasant (Phasianus be occurring in other populations of Chukars 2003J NOTES 405 or in other bird species in arid environments KENDALL, R.j., T.E. LACHER, JR., C. BUNCK, B. DA:-lIEL, C. should be investigated. Continued documenta­ DRIVER, C.E. GRUE, E LEICHTO:-l, ET AL. 1996. An ecological risk assessment of lead shot exposure in tion ofthis situation is necessary to evaluate the non-waterfowl avian species: upland game birds and overall impact of lead shot on ground-foraging raptors. Environmental Toxicology and Chemistry birds, especially in light of improved alterna­ 15:4-20. tives to lead shot. KNIGHT, R.L., A.D. AVERY, A."iD A.W ERICKSO:-l. 1979. Sea­ sonal food habits of four game bird species in Okanogan County, \VA. Murrelet 60:58-66. The Oregon Department of Fish and Wild­ LEWIS, J.C., A~D E. LECLER, JR. 1968. Lead shot ingestion life provided support and funding for this pro­ by Mourning Doves and incidence in soil. Journal of ject. The Department of Fish and Wildlife Wildlife Management 32:476-482. Resources at the University ofIdaho provided LINDBLom.l, A. 1998. Habitat use, reproduction, move­ ments, and survival of Chul-ar Partridge in west· research and laboratory facilities. We thank K. central Idaho. 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Climatological data-Oregon. Volume 104. Partridge in western Nevada. Master's thesis, Uni­ National Climatic Data Center, Asheville, NC. versity of Nevada, Reno. OREGON DEPARTMENT OF FISH .....ND WILDLIFE. 1998. Guide _-,,,. 1970. The Chukar Partridge: its introduction, life to upland gamebirds in Oregon. Oregon Department history. and management. Biological Bulletin 4, of Fish and Wildlife, Portland. Nevada Department ofFish and Game, Reno. S.....NDF"OIIT, WW 1954. Evaluation of Chukar Partridge o 1996. Chukar (Alectoris chukar). In: A. Poole and range in Colorado. Proceedings ofthe Western Asso­ --"F.Gill, editors, The birds of North America No. 258. ciation of Fish and Game Commissioners 32:244-250. The Birds of North America, Inc., Philadelphia, PA. SIMBERLOFF, D., AND B. VON HOLLE. 1999. Positive inter­ COLE, F.R., L.L. LooPE, A.C. MEDEIROS, J.A. RAKES, AND actions of nonindigenous species: invasional melt­ e.S. WOOD. 1995. Conservation implications of intro­ down? 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Apparent lead poisoning in a wild ment 26:393-400. bobwhite. Wilson Bulletin 78:471-472. HARPER, H.T., B.H. HARRY, A~D WD. BAILEY. 1958. The WIIISENANT, S.G. 1990. Changing fire frequencies on Chukar Partridge in California. California Fish and fdaho's Snake River plains: ecological and manage­ Game 44:5-50. ment implications. Pages 4-11 in Proceedings of HIRO~AKA, M., M.A. FOSBERG, ...... ;.\0 A.H. WIXWARD. 1983. the symposium on cheatgrass invasion, shrub die·off, Sagebrush-grass habitat types of southern Idaho. and other aspects of shrub biology. USDA Forest Bulletin 35, University of Idaho, Forest, Wildlife, Service General Technical Report INT-276. and Range Experiment Station,University of Idaho, ZDlBAL, R.L. 1977. The feeding habits of the Chukar Par­ Moscow. tridge, Alectom chukar; in the Argus and Coso HUNTER, B.F., AND M.N. ROSEN. 1965. Occurrence orJead Mountains of California. Master's thesis, California poisoning in a wild pheasant (Phasianus colchicus). 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