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Great Basin Naturalist54(4), © 1994,pp.329-334 HABITAT PREFERENCE AND DIURNAL USE AMONG GREATER SANDHILL CRANES Donald E. Mclvorl and Michael R. Conover^ — Abstract. We e.xamined patterns ofhabitat use by Greater Sandhill Cranes {Grits canadensis tahicla) in the Interniountain West, April-October 1991-92, to determine whether cranes exhibited a specific preference for crops, fields, andareaswithin afield. This information will helpfarmersandwildlife managers directnonlethalcontrolmeth- odstothesiteswherecranedamageis mostlikelytooccur.Weconductedsurveysalongtwo37-kmtransectsweeklyin CacheValley, Utah,andbiweeklyin BearRiverValley, RichCounty, Utah,and LincolnCounty,Wyoming. Werecorded 5814 cranes in 662 separate groups. Most were located in pasture/hay (34%), small grain (39%), alfalfa (9%), plowed (9%), fallow(4%),orcom(1%)fields.Anindexoffeedingactivityforeachfieldandhabitattypesuggestedcranes fedat approximately the same rate in each field and habitat type. Crane diurnal activity patterns during summer and fall revealedthatgrainfieldswereusedheaviK-throughouttheday. Keywords:GreaterSandhillCranes, Gruscanadensistabida,habitat, depredation, diurnalactivity, Utah, Wyoming. The most recent population estimate for ows and grainfields ranged from 69 to 100% the Rockv Mountain Greater Sandhill Crane (Rowland etal. 1992). is 17,000-20,000 (Drewien et al. 1987:27). We examined habitat preferences and for- Records oflocal summer populations are less aging habits of summer resident Sandhill complete, but the crane population in Cache Cranes because of increasing depredation Valley, Utah, has increased from 14 individuals complaints from farmers growing corn and in 1970 (Drewien and Bizeau 1974) to approx- small grains (e.g., barley, oats, rye, wheat) in imately 200 in 1990 (Bridgerland Audubon Cache and Rich counties, Utah. As one means Society 1990). Between 1985 and 1987, of evaluating these problems and potential Rowland etal. (1992) reported 255 cranes sum- solutions, we tested the hypothesis that crane meringin Lower Bear RiverValley, Wyoming. use was concentrated in corn and small-grain Crop depredation complaints attributed to fields in particular and in agricultural fields in cranes are risingconcomitantlywith population general. High use of a field may alarm a numbers (Lockman et al. 1987). In response to farmer, but little damage may occur if birds depredation complaints, Wyoming instituted a are not foraging. Hence, we also tested the limited Sandhill Crane hunt in 1982. Utah in- hypothesis that cranes forage in habitats in stituted a hunt in 1989, but the decision gen- proportion to their availability. In addition, we erated enough public controversy that the assessed whether habitat use varied diumally huntwas canceled in 1992. during summer and fall. Additional questions Cranes are omnivorous (Mullins and Bizeau relevant to selecting an appropriate scale for 1978) and readily feed in agricultural lands, management include (1) whether cranes use although habitat use seems to vary widely. all fields available to them or concentrate their Agricultural fields comprised 91% of habitat activities in a few fields, and (2) how cranes used by wintering cranes in western Texas distribute theiractivities within fields. (Iverson et al. 1985). During spring staging in Nebraska, Krapu et al. (1984) reported that Methods 70% of habitat use was in agricultural lands. Withinagricultiualfields 99%ofusewas incom The study areais in CacheValley, Utah, and stubble. Approximately 80% ofspring diurnal Bear River Valley, Utah and Wyoming, and habitat use in Alaska was in barley (Iverson et includes three contiguous counties: Cache and al. 1987). In Wyoming crane use ofwet mead- Rich counties in northern Utah and Lincoln ^DepartmentofFisheriesandWildlife,UtahStateUniversity,Logan,Utah84322. 329 330 Great Basin Naturalist [Volume 54 County in southwestern Wyoming. A compre- by the distance within which 90% ofall cranes hensive description ofthe area is inchided in had been located duringweekly siuAcys. Mclvor and Conover (1992). Cranes normally An index offeeding activity was developed occup\' the region from April until early to allow comparison among habitat types. October When > 1 crane was sighted, an individual was To determine patterns of field use, we chosen at random from the flock and observed established a 37-km transect in Cache Valley for 1 min to determine ifthe bird was feeding. and another in Bear River Valley. The tran- The result was a logical variable (feed/no sects traversed a sample ofhabitat types avail- feed), and these data were compiled and com- able to cranes, including cultivated fields, pas- paredacross habitat types. tures, and natural habitats. Sampling was con- Quantitative analyses were based on meth- ducted based on a visual sui^vey method simi- ods devised b>' Neu et al. (1974). We used a lar to that used by Iverson et al. (1985, 1987). goodness-of-fit test (F < .05) to examine the Transects were surveyed weekly in Cache hypothesis that cranes used habitats in pro- Valley and biweekly in Bear River Valley from portion to habitat availability, and to deter- April through mid-October 1991-92. mine whether cranes fed preferentially in cer- Surveys began 2 h after sunrise from a tain habitat types. We used a Bonferroni Z-sta- vehicle moving at 40 km/h. Habitats on both tistic to test for habitat and feeding prefer- sides ofthe transects were scanned systemati- ence. The Z-statistic and resulting family con- cally. As cranes were located, avariety ofpara- fidence intei^val for testing each contingency meters, including type ofhabitat in use, were table cell were generated using a Monte Carlo recorded. Habitat was categorized by crop sampling simulation from a binomial distribu- (alfalfa, com, small grain, pasture, hay, ormixed tion, on a mainframe computer using Minitab (1989). use) or groundcover type (riparian, sage [Arte- In 1992we mapped die distribution ofgrain- moifsciraasnpeps.]wistcrhuibn).fiTeoldse,xawmeinreectoherddeidsttrihbeutdiiosn- and cornfields along the sui"vey transects. We then compared distribution ofavailable fields tance between field edge and the individual with the frequency distribution of cranes crane closest to the edge using a range finder obsei"ved to test the Hg ofequal use among all These data produced a distance-to-edge esti- grain- and cornfields. These data were ana- mate, which we used as a general indication of lyzed usingagoodness-of-fit test. whether cranes preferentially used edges or Patterns ofdiunial habitatusewere recorded interiors of fields. Using the range finder, we overa5-d period inJune 1991 usingboth tran- also recorded minimum distance from the sects andduring September 1992 usingonlythe transect to the crane flock. Cache Valley transect. Data-collection methods Each sighting of cranes was given equal were identical to those used in the haliitat-use weighting in constructing contingency tables sui"vey described above, except that transects to maintain statistical independence among were sampled 5 times/day: sunrise, 2 h after field-use obsei"vations. A few observations of sunrise, noon, 4 h before sunset, and 2 h before cranes were made in mixed-use fields and on sunset. rural roads. These sightings were combined We used PC-SAS (SAS Institute, Inc. 1988) under the miscellaneous category. Early sea- and the PROC CATMOD routine to examine son hayfields were difficult to distinguish from June 1991 diurnal-use data, and the PROC pastures, and these obsen'ations werepooled. FREQ routine to examine September 1992 Habitat availability was quantified along data. Both SAS routines used a goodness-of-fit each transect in July 1991 and 1992. A sample test (F < .05) to examine the null hypothesis of 125 random points on each transect was that cranes maintained the same pattern of selected a priori, and each point was located field use throughout the day. and its habitat type recorded. To be selected as representative ofhabitat, each point had to Results meet two criteria. First, any sampling point not visible from the transect was not used. Fifty-three sui-veyswere conducted in Cache Second, the peri:)endicular distance from tran- Valley and29 in Bear RiverValley. During two sect to sampled habitat locations was bounded field seasons we recorded 5814 cranes in 662 1994] Sandhill Crane Habitat Preference 331 groups. Most groups were observed in pas- 1991-92, a crop not cultivated in Bear River ture/hay (34%), small grains (39%), alfalfa (9%), Valley. Analysis indicated variation in habitat plowed fields (9%), fallow (4%), or cornfields availability between years along each transect, (1%). Remaining cranes were located in ripari- although the change was not statistically sig- an (3%), sagebrush (1%), and miscellaneous nificant (P = .2230). For these reasons, col- (2%) habitats. lapsing the contingency tables across sample Habitat availability differed between the sites or across years would have made the two survey transects (Table 1). Although the results ambiguous. Cache Valle\' transect contained no sagebrush Cranes were not distributed randomly habitat, the Bear River Valley transect con- among nine available habitats in either 1991 tained extensive sagebrush (61% in 1991, 58% (X2 = 374.0, df= 13, P < .005) or 1992 {X^ = in 1992). Conversely, the Cache Valley tran- 464.1, df = 14, P < .005). Along the Cache sect contained a small amount ofcorn (7%) in Valley transect, cranes avoided alfalfa and Table L Habitat availabilitv, use, and selection among Sandhill Cranes in Cache Valley (C), Utah, and Bear River Valley(B), UtahandWyoming.'in 1991and 1992. Habitat 332 Great Basin Naturalist [Volume54 miscellaneous habitats in both years, selected transect, primarily with newly planted corn grain and plowed habitats in excess of their crops. Cranes pulled up corn plants and con- availabilit\', and used pasture in proportion to sumed the still-attached seed. Farmers also its availability. Along the Bear River transect, reported minor damage from cranes trampling cranes avoided sagebrush habitat, selected emergent alfalfa and small grains (winter grain and pasture habitats, and used alfalfa wheat, barley, oats). The growing season along and plowed habitat types in proportion to the Bear River transect in Rich and Lincoln their availability. Results from other habitat counties is too short for corn production, and types along the two transects either varied crop damage occurred primarily in the fall, between years or were not tested due to pat- affecting small-grain crops (Lockman et al. terns of sampling or structural zeros in the 1987, Mclvor and Conover 1994). Some tram- contingency tables. pling damage in spring was also leported in We examined distribution of cranes using this area. grain- and cornfields in 1992 and found that Cranes concentrated activities in small-grain certain grainfields received preferential use in fields during our surveys. Fields planted in Cache Valley {X^ = 272.4, df = 72, F < .001) corn constituted only 7% ofavailable habitat, and in Bear River Viilley {X^ = 42.6, df = 10, and <3% ofcranes sighted were in corn. Most P < .001). Insufficient data were available for activity in cornfields occurred during germi- cornfields in 1992. Cranes tended to exploit nation or while plants were young. Thereafter, field interiors but were broadly distributed cranes avoided cornfields until han^est. within fields. In 1991-92 mean distance-to- Large expanses of sagebrush habitat were field-edge for flocks in corn was 82.2 m (n = little used, although they constituted about 7, SE = 21.2) and 72.1 m {n = 2,50, SE = 60% of available habitat. Sagebrush habitat 7.26) for flocks usinggrainfields. may have reduced crane foraging efficiencyby Cranes were recorded feeding in 75% of creating dense cover, limiting movement, and our observations. A goodness-of-fit test was offering few plant foods. Agricultural fields in used to examine the distribution of cranes Bear River Valley were surrounded by vast feeding in each habitat type in comparison to expanses of sagebrush, a condition that may habitat availability (Table 2). Feeding cranes have concentrated cranes into agricultural = were not distributed randomly in 1991 (A- fields. 242.8, df = 13, P < .0005)'or 1992 {X^ = Feeding activity closely approximated pat- 332.4, df = 14, P < .0005). Distribution of terns ofhabitat use, suggesting cranes fed with feeding cranes approximated distribution ofall the same intensity in each habitat t\'pe. Migrat- cranes obsei^ved, except in the case ofriparian ing cranes in Nebraska relied on a diversity of habitat along the Bear River transect. While habitats to provide various components of cranes used this habitat type disproportionate- their diet (Reinecke and Krapu 1986). Alfalfa ly to its availability in 1991, they appeared to fields (Walker and Schemnitz 1987) and grass- feed in this habitat type in proportion to its lands (Reinecke and Krapu 1986) provided a availability. Data for 1992 were insufficient for source of invertebrates for cranes. Although analysis. invertebrates may provide certain proteins Crane diurnal use offield types varied with absent from plant foods (Reinecke and Krapu time of day (summer diurnal sampling: X^ = 1986), they comprise only a small component 91.04, df = 48, P = .0002; fall diurnal sam- of the diet, varying from 3% (Reinecke and pling: X2 = 72.65, df = 24, P < .01). Crane Krapu 1986) to 27% (Mullins and Bizeau 1978). numbers peaked after sunrise, decreased In this study cranes appeared to avoid feeding steadily throughout the day, and then in Cache Valley alfalfa fields, possibly obtain- increased again before sunset. ing invertebrates from pastures or plowed fields. In Bear RiverValley cranes fed actively Discussion in pasture. Corn (Reinecke and Krapu 1986) and cere- Crop depredation attributed to cranes was al grains (Krapu and Johnson 1990) provide reported by farmers in Cache, Rich, and important nutrient sources for fat synthesis in Lincoln counties (Mclvor 1993). Crane dam- cranes. Habitat use and feeding activity in age occurred in spring in the Cache Valley grainfields, along both transects and in both 1994] Sandhill Crane Habitat Preference 333 Table2. DistributionofSandliillCranesobservedfeedinginvarioushabitattypesinCacheValley(C), Utali,andBear RiverValle>'(B), UtahandWVoming,in 1991 and 1992. Habitat 334 Great Basin Naturalist [Volume 54 concentration of cranes in small-grain fields, and distribution. L'Tipuhhshed report, Logan, Utah. npaormtiiccultahrrleyatintothfearfamlel,rsp.osDeeslaaypeodtehntairavlesetcoo-f Dhkwi8tkrpinpb,.utRi.onC,ofaGnrdeaEt.erG.SaBnidzheialul.C1r9a7n4.esStiantutsheanRdocdiksy- grains in fall due to wet weather is likely to Mountains. Journal of Wildlife Management 38: exacerbate the problem because standing 720-742. grain remains available to an increasing num- Drewien, R. C, W. M. Brown, and J. D. Varley. 1987. ber of prestaging cranes (Lockman et al. TheGreater Sandhill CraneinYellowstone National Park:apreliminaiysurvey. Proceedingsofthe North 1987). AmericanCraneWorkshop4:27-38. Diurnal changes in habitat use may allow IVERSON, G. C, R A. VOHS, AND T. C. Tacha. 1985. cranes to forage while minimizing heat stress. HabitatusebySandhillCraneswinteringinwestern Cranes usingpastine and hayfields in midafter- Texas.JoumalofWildlifeManagement49: 1074-1083. 1987. Habitat use by mid-continent Sandhill noon were probably loafing before feeding . Cranes during spring migration. Journal ofWildlife prior to sunset. For reasons that are unclear, Management51:448-458. activity patterns observed in Cache Valley Johnsgard, E A. 1991. Crane music: a natural history of were less distinct in Bear River Valley. Cranes American cranes. Smithsonian Institution Press, may have moved less, visiting fewer habitat KrapuW,asGh.inL.g,toann,dDD..C.H.13J6ophpn.son. 1990. Conditioningof types as aresult ofthe pattern ofhabitat distri- Sandhill Cranes during fall migration. Journal of bution in Bear River Valley. Additionally, the WildlifeManagement54:23-^238. Bear River Valley survey may have included a Krapu, G. L., D. a. Facey, E. K. Fritzell, and D. H. greater proportion of paired individuals, Johnson. 1984. Habitat use by migrant Sandhill which remained on territories during early Cranesin Nebraska.JournalofWildlife Management 48:407-417. summer (Johnsgard 1991) and subsequently Lockman, D. C, L. Serdiuk,and R. Drewien. 1987. An visited fewerhabitat types. experimental Greater Sandhill Crane and Canada Crane depredation occurs under two dis- Goose hunt in Wyoming. Proceedings ofthe North parate conditions: in association with spring AmericanCraneWorkshop4:47-57. McIvoR, D. E. 1993. Incidence and perceptions of planting ofcorn and just before fall hai-vest of Sandhill Crane crop depredations. Unpublished cereal grains. Encouraging rapid germination master'sthesis, UtahStateUniversity,Logan.75pp. ofcorn and early harvest ofgrains would mini- McIvoR, D. E., and M. R. Conover. 1992. Sandhill mize availability of these resources to cranes Crane habitat use in northeastern Utah and southwestern Wyoming. Proceedings of the North during periods of susceptibility to depreda- AmericanCraneWorkshop6:81-84. tion. Crane damage was concentrated in a few 1994. ImpactofGreaterSandhill Cranes foraging . fields, rather than being evenly distributed in on corn and barley crops. Agriculture, Ecosystems, all fields, indicating that nonlethal techniques andEnvironment49:233-237. to alleviate these problems need to be focused MiNlTAB. 1989. Minitab statistical software. Release 7.2. in these same fields. Farmers who experience MuLLiMNisn,itWab,HI.n,c.a,nSdtaEte.CGo.llBeigzee,auP.enn1s97y8l.vaSniuam.mer foods chronic depredation problems may wish to ofSandhillCranesinIdaho.Auk95: 175-178. consider the economic feasibility ofproducing Neu, C. W, C. R. Byers, and J. M. Peek. 1974. A tech- crops less prone to crane damage. nique for analysis ofutilization availability data. JournalofWildlife Management38:541-545. Acknowledgments ReineocfkeS,anKd.hiJ.l,lanCdraGn.esL.dKur.r4iPnU.g1s9p8r6i.nFgeemdiignrgateicoolnog>i'n Nebraska. Journal ofWildlife Management 50: Project funding was provided by the Utah 71-79. State UniversityWildlife Damage Management Rowland, M. M.. L. Kinter, T. Banks, and D. C. Lockman. 1992. Habitat use by Greater Sandhill Program and the Utah Division of Wildlife Cranes in Wyoming. Proceedings ofthe North Resources. We thank D. A. Brink, K. V Dustin, AmericanCraneWorkshop5:82-85. and H. Lowforfield assistance. R. S. Krannich, SAS Institute, Inc. 1988. SAS/STAT user's guide. Jh.elAp.fuBlismsaonnuestctrei,ptanrdevPi.ewMs., aMnedyeS.rsL.pDruovrihdaemd WalkeCRraer,loelaDis.neaL.6..,100a32ne8ddiptSpi..onD..SSAcSheImnnstiittzut.e,1I9n8c7.., CFoaoidyhNaobritths gave invaluable assistance with matters statis- ofSandhill Cranes in relation to agriculture in cen- tical. tral and southwestern New Mexico. Proceedings of theNorthAmericanCraneWorkshop4:201-212. Literature Cited Received2September1993 Accepted20April1994 BridgerlandAudubon SociEri. 1990. Resident Saiulhill Crane popiilatioTis in Cache CJounty, Utah; numbers