Northern Harrier Predation on Greater Prairie Chickens in Southwest

146 SHORTCOMMUNICATIONS VOL. 19, NO. 4

Northern Harrier Predation on Greater Prairie forbs,as well asinvading cool season grasses such as fescue (Festuca Chickens in Southwest Missouri sp.).Old and reclaimedstrip mines and deciduouswoody growth are scatteredthroughout the area.Neighboring lands are mostly cropsand fescue(Larson 1982). BRIAN TOLAND A total of 325 h were spentobserving harriers and prairie chickensfrom 7 April - 7 August1984. Using techniquesde- Although habitatpreferences of the Northern Harrier (Circus scribedby Hamerstrom(1969), I found 7 harrier nests(density of cyaneus)and the Greater PrairieChicken (Tympanuchus cupido) are 1 pair/121 ha) clumped in 3 looseaggregations in undisturbed quite similar (Berger et al. 1963), harriers are rarely reported to grasslands. prey upon these galliformes(Yeatter 1943; Schwartz 1945; Approximately150 prairiechickens were concentrated around Grange 1948; Weller et al. 1955; Ammann 1957; Berger et al. 4 booming grounds on the study area during early spring 1963). Other similar-sizedavian prey suchas Ring-neckedPheas- (April-May) and later scatteredthroughout the area during nest- ant (Phasianuscolchicus), Sharp-tailed Grouse (T. phasianellus), ing (May-July).At least2 prairiechicken nests were located within American Bittern (Botauruslentiginosus), ducks and the Domestic 200 m of 2 harrier nests. Chicken(Gallus spp.) are, however,not infrequentlytaken (Fisher Visitsto Northern Harrier nestsduring the nestlingstage were 1893; Peabody 1900; Errington and Breckenridge 1936; Bent madeto collectprey remains and/or pellets.! calculatedfrequency 1937; Brown and Amadon 1968) although usually asjuveniles of occurrenceof preytypes from freshpellets and identifiedprey (Peabody0p. cit.; Saunders1913;Randall 1940; Hecht 1951). remains.Percent composition of eachprey specieswas calculated This notereports harrier predationon adult and youngGreater from the number of each type divided by the total. Percent PrairieChickens in the tall-grassprairie region of southwestMis- biomasswas estimated by weightsgiven in Schwartzand Schwartz souriduring springand summer1984. The studyarea of 850 ha (1959), Terres (1980) and Steenhof (1983). consistedof Prairie State Park and surrounding private lands. Analysisof food itemsrevealed a catholicdiet (Table 1). The Prairie State Park is 1 mi southwestof Liberal, Missouri, in Barton diet of nestingNorthern Harriers in other regionshas been of a County.Vegetation consists ofbluestem grasses (Andropogon spp.), similareuryphagus composition (Randal op. cit.; Hecht op. cit , Indian grass(Sorghastrum nutans) and other native grassesand Craigheadand Craighead 1956; Brown and Amadon 1968;Smith

Table 1. Preyof nestingNorthern Harriersat PrairieState Park in southwestMissouri, 1984.

FREQUENCY AVERAGE OF % WEIGHT (G) ESTIMATED PREY OCCURRENCE COMPOSITION % BIOMASS

BIRDS

Greater Prairie Chicken 8 6.6 624 22.6 (Tympanuchuscupido ) Adults 3 908 12.3 Juveniles 5 454 10.3

Mourning Dove 3 2.5 134 1.8 (Zenaidamacroura )

Eastern Meadowlark 6 4.9 95 2.6 (Sturnellamagna)

Common Grackle 2 1.6 112 1.0 (Quiscalusquiscala ) Red-wingedBlackbird 6 4.9 50 1.4 (Agelaiusphoeniceus )

Brown-headed Cowbird 3 2.5 41 0.5 (Molothrusater)

Unidentified passerines 11 9.0 75 3.7

Total birds 39 32.0 33.6 (Table 1 continued) WINTER 1985 S•IORT COMMUNICATIONS 147

(Continuation of Table 1)

MAMMALS

Prairie vole 24 20.0 8 4.1 (Microtusochrogaster)

Fulvous harvest mouse 4.9 21 0.5 (Reithrodontomysfulvescens )

Deer Mouse 1.6 20 0.2 (Peromyscusmaniculatus )

Cotton rat 0.8 120 0.5 (Szgmodonhispidus )

Eastern wood rat 0.8 255 1.2 (Neotomafloridana )

Unidentified rodents 5.8 30 0.9

Eastern cottontail 7.4 1200 49.0 (Sylvilagusfloridanus )

Total mammals 50 41.3 56.4

REPTILES

Plainsgarter snake 1 0.8 109 0.5 (Thamnophisradix )

Unidentified snakes 11 9.1 190 9.5

Total reptiles 12 9.9 10.0

INSECTS

Coleopterans 12 9.9 0.5 tr •

Orthopterans 8 6.6 1 tr

Total insects 20 16.5 tr

TOTAL PREY ITEMS 121 100.0 100.0

•tr = trace.

and Murphy 1973; Snyderand Wiley 1976). A total of 7 prairie harrier returned to her kill after nearly 20 min. Berger et al. chicken remains were collected from the 2 harrier nests closest to (1963) observedprairie chickensbeing captured by raptors (in- prairie chicken nests.Of these 7 remains,5 representedhalf- cluding 1 female Northern Harrier) early in the morning. grownjuveniles and 2 representedadults. Campbell (1950) reported an unsuccessfulcapture attempt of a An eighth prairie chickenwas captured by an adult female LesserPrairie Chicken (T. pallidicinctus)during evening hours. harrieron 25July at 0700 H. The hawkhovered briefly 4 m above Poorlight during earlymorningand late evening hours may make a densestand of bluestemgrasses and fescue,before diving into approachingraptors more difficult for prairie chickens(or other the vegetation.After waitingabout 10 min, I approachedthe site quarry) to spot(Berger et al. 1963). and the hawkflushed when I wasabout 20 m away.I discovereda All prairiechicken prey was brought to harrier nestsduring the dead adult female prairie chickenthat was partly deplumed and last half'of the nestlingstage. During this time female harriers stdl warm. I was unable to find a prairie chicken nest in the spentas much time hunting for their young as did males. It is •mmediatevicinity, but numerousdroppings and matted vegeta- probablethat the larger females(50% heavierthan adult males) non (form) indicatedthat the prairie chickenhad beenon itsroost. caught the adult prairie chickens(Berger et al. 1963). I observed I left the site and watched from a distance of ca 300 m until the severaladult male harriers feeding on mammalian prey among 148 SHORT COMMUNICATIONS VOL. 19, NO 4 displayingprairie chickens at boominggrounds just prior to the populations: their biologyand decline. Univ. Wiscon- nestingseason. The prairiechickens seemed oblivious of these sin Press, Madison. male harriers. Female harriers, however, usually evoked a re- HECHT,W.R. 1951. Nestingof the Marsh Hawk at Delta, sponsefrom prairie chickens, ranging from a briefsquat to an all Manitoba. Wilson Bull. 63:167-175. out flush.Berger et al. (1963)reported that over a 4-yearsample LARSON,L. 1982. Prairie State Park: an introduction to of harrier-prairiechicken reactions, prairie chickensflushed one of Missouri'spublic prairies. MissouriPrairie J. nearly70% of the timesfemale harriers approached, but only 30% 3:4-11. of the timesmales approached. Of the 33 timesthat prairie chickens completelyignored approachingharriers, 94% were male MARQUISS,M. 1980. Habitat and diet of male and female hawksand 6% were females.Female Hen Harriers (C. c. cyaneus) Hen Harriers in Scotland in winter. British Birda take significantlymore Red Grouse(Lagopus lagopus) and other 73:555-560. gamebirdsthan do males(Marquiss 1980). Peabody, P.B. 1900. How a Marsh Hawk grows. Btrd I have found no evidenceof Northern Harriers preying on Lore 2:43-49. GreaterPrairie Chickens during winter or on boominggrounds in RANDALL,P.E. 1940. Seasonal food habits of the Marsh earlyspring. However, prairie chickens did comprisea significant Hawk in Pennsylvania.Wilson Bull. 52:165-172. proportionof Northern Harrier diets(22.6% biomass;Table 1) SAUNDERS,A.A. 1913. A study of the nesting of the during the nestingseason when femaleand juvenile prairiechick- Marsh Hawk. Condor 15:99-104. ens in closeproximity to harrier nestsmay be more vulnerableto raptor predation. SCHWARTZ,C.W. 1945. The ecology of the prairie chicken in Missouri. Univ. Missouri Studies 20:1-99. AND E.R. SCHWARTZ. 1959. The wild ACKNOWLEDGMENTS mammals of Missouri. Univ. Missouri Press and Mis- Toney Chilescontributed invaluable field assistance.The Mis- souri Dept. Conserv. souri Departmentof Natural Resourcesprovided funding and SMITH,D.G. ANDJ.R.MURPHY. 1973. Breeding ecology technicalassistance for this studythrough a state park research ofraptors in the easternGreat Basinof Utah. Brigham grant. NancyThompson-Toland helped with expensesand field Young Univ. Sci.Bull., Biol. Ser., Vol. 28(3). work. Keith Bildstein,Clayton White and an anonymousreferee SNYDER,N.F.R. ANDJ.W. WILEY. 1976. Sexual size di- made editorialsuggestions which improved the manuscript. morphismin hawksand owlsof North America.AOU

LITERATURE CITED Monogr. 20. STEENHOF,K. 1983. Preyweights for computingpercent AMMANN,G.A. 1957. The prairie grouse of Michigan. biomassin raptor diets.Raptor Res. 17:15-27. MichiganDept. Conserv.Tech. Bull. 200 pp. TERRES,J.K. 1980. The Audubon Soc.encyclopedia of BERGER, D.D., F. HAMERSTROM AND F.N. HAMER- North American birds. Alfred A. Knoopf, Inc., New STROM.1963. The effect of raptors on prairie chic- York. kenson boominggrounds. J. Wildl.Manag. 27:778- WELLER, M.W., I.C. ADAMS, JR. AND B.J. ROSE. 791. 1955. Winter roosts of Marsh Hawks and Short-eared BENT, A.C. 1937. Life historiesof North American birds Owls in central Missouri. Wilson Bull. 67:189-192. of prey (order Falconiformes).Part 1. U.S. Natl. Mus. YEATTER,R.E. 1943. The prairie chickenin Illinois.I1- Bull. 167. Dover Publ., New York. linois Nat. Hist. Surv. Bull. 22:377-416. BROWN,L.H. ANDD. AMADON.1968. Eagles,hawks and falcons of the world. McGraw-Hill, New York. Missouri Department of Natural Resources,Natural History CAMPSELL, H. 1950. Note on the behavior of Marsh Program,P.O. Box 176,Jefferson City, MO 65102. Current Hawks toward Lesser Prairie Chickens. J. Wildl. address: Route 4, Box 165, Columbia, MO 65201. Manag. 14:477-478. CRAIGHEAD,J.J. ANDF.C. CRAIGHEAD,JR. 1956. Hawks, Received8 April 1985; Accepted15 July 1985. owlsand wildlife. StackpoleCo., Harrisburg, PA. ERRINGTON,P.L. ANDW.J. BRECKENRIDGE.1936. Food habitsof Marsh Hawks in the glaciatedprairie region of north-central United States. Am. Midl. Nat. 7:831- 848. FISHER, A.K. 1893. The hawks and owls of the United Statesand their relationto agriculture.U.S. Dept. Agr. Bull. 3, Washington,D.C. GRANGE,W.B. 1948. Wisconsingrouse problems. Wis- consinConserv. Dept. 318 pp. HAMERSTROM,F. 1969. A harrier population study. Pages367-383. InJ.J. Hickey(Ed.), PeregrineFalcon