University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln

Symposium Proceedings—Coyotes in the Southwest: A Compendium of Our Knowledge Wildlife Damage Management, Internet Center (1995) for

April 1995

TECHNIQUES FOR ESTIMATING COYOTE ABUNDANCE

Scott E. Henke Texas A&M University- Kingsville, Kingsville, TX

Fred F. Knowlton USDA-APHIS

Follow this and additional works at: https://digitalcommons.unl.edu/coyotesw

Part of the Environmental Health and Protection Commons

Henke, Scott E. and Knowlton, Fred F., "TECHNIQUES FOR ESTIMATING COYOTE ABUNDANCE" (1995). Symposium Proceedings—Coyotes in the Southwest: A Compendium of Our Knowledge (1995). 28. https://digitalcommons.unl.edu/coyotesw/28

This Article is brought to you for free and open access by the Wildlife Damage Management, Internet Center for at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Symposium Proceedings—Coyotes in the Southwest: A Compendium of Our Knowledge (1995) by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. TECHNIQUES FOR ESTIMATING COYOTE ABUNDANCE

SCOTT E. HENKE, Caesar Kleberg Wlldlife Research Institute, Campus Box 2 18, Texas A&M University- Kingsvllle, Kingsville, TX 78363

FRED F. KNOWLTON, USDA-APHIS Denver Wildlife Research Center, Utah State Univers~ty,Logan, Utah 84322-5295

Absirad Knowledge of coyote abundance is needed to make intelligent management decisions Several methods have been devised to ennumerate coyote (Canis latrans) population size. We review several techniques and attempt to identify biases associated with each method. Once biases are understood, recommendations can be made to minimize theu impact on data collection processes and yield better estimates of coyote population trends.

Enumerat~onof population status (i e ,denslty, Methods used to estimate coyote population trends) is impostant in research and management of slze, dens~ty,and relative abundance have included wildlife. Management of coyote populations has scent stations (Linhart and Knowlton 1975, typically involved population control (Beasom Roughton and Sweeney 1982), vocalization 1974). Ranchers may be interested in the number of responses (Okoniewsk~and Chambers 1984), scat coyotes in an area to assess the potentla1 severity of counts (Andelt and Andelt 1984), mark-recapture livestock losses (Scrivnel- et al. 1985). Wildlife (Clark 1972), removal (Z~ppln1958), rad~oisotope managers sometunes attempt to reduce the density of markers (Crabtree et al 1989), aerial surveys (Nellis coyotes to aid I-ecruitment of game species (Beasom and Keith 19761, and radiotelemet~y(Andelt 1985) 1974, Gamer et al. 1978, Hamlin et al. 1984) However, all methods provide vanable results and Assessing populat~onslze has been 1 method to none glve a complete census of coyote populations judge the success of such management PI-ograms. (Spowal-t and Samson 1986). A census is a Unfo~tunately,estimation of coyote population size complete count of evely animal within the is difficult because of species' secretive behaviol- and populat~on Obv~ously,because of the behavior of low dens~t~es. coyotes, a census is not practical

Coyote populat~onsize can be expressed as Our purpose here is to identify methods which density or relative abundance. However, these te~ms can be used to assess coyote abundance and to are sometimes confused and used erroneously. ~dentifysome mer~tsand problems of each. While Population density is the number of individual not an exhaustive treatment of the subject, this report animals per unit al-ea, for example, the number of provides a general assessment of our current coyotes pel- square mile Relat~veabundance refers undcl-standings to the ranking of populations according to their population size. For example, Ranch A has more coyotes than Ranch B. Often, relative abundance is Density estimates derived fi-om an index or an ind~catorof population size. Aet.~alColrrits. Aerial sulveys are commonly used to sample animals or animal signs (e.g., nest Reseaschers of coyotes often rely on population colonies) visible from the alr. Aerial counts can be indices because of the d~fficulty in obtaining conducted from e~ther a fixed-wing plane or adequate data to estimate population size. However, helicopter. No~~nally,a pilot and 1 or 2 observers because the relationship between the ~ndexand the are requlred to conduct aerial sulveys. A Global true population size is often unknown, the use of Positioning System (GPS) is useful in mainta~nlng indices should be restl-icted to measures of relative flight patterns (R. Cumow, Denver Wildl. Res abundance between populations of different areas Center, pers. cornrnun.) Surveys should be duing the same time period, or between populations conducted when there is adequate visibility during on the same area over time. the ewly mo~ningor late aftelnoon hours (Beasom et al. 198 1). However, there have been few serious attempts the use of traps exists over concern that substantial to use aerial counts, either from planes or injury to the trapped animals occurs (Jotham and helicopters, to assess coyote abundance. Equipment Phillips 1994). Llnhart et al. (1 98 1) and Zemlicka costs may make the technique prohibitive for many and Bruce (1 99 1 ) suggested that affixing tranquilizer situat~ons,and biases assocrated wrth aircraft speed tabs containing pl-opiopromazine HCI can and height above ground, transect width, differing significantly decrease foot injury to coyotes. The ground cover and tei~ain, differing vegetation dug diazepam also has been used to reduce Injury to conditions, time of day, and visual acuity of coyotes caught in steel foot-hold traps (Balser 1965). observers probably precludes this technique as a reliable procedure except under very specialized Neck snares equipped with safety stops to circumstances (e.g., snow cover). Use during the pl-event choking have been used to reduce injury to winter after deciduous foliage has fallen and where individual animals, and capture rates are typically there is complete snow cover on the ground may greater than those of foot-hold traps (Guthery and improve the performance of this technique (Nellis Beasom 1978), at least in areas where net-wire andKeith 1976); however, little or no evaluation of fences are common. Also, experience in the the estimates obtained have been made. placement of the safety stops is required; too tight or too loose will result in killing the coyote or escape For~vard-Look~ngInf'sar-ed (FLIR) sensing by the coyote, respectrvely. Coyote pups have been shows promlse as a new teclmrque to count caught at dens In live traps (Foreyt and Rubenser predators A plane equipped wrth a FLIR deuce 1980); however-, adult coyotes seldom enter boxtraps would fly tl-ansects as outlined above, except the (R Sramek, Texas Animal Damage Control Serv., intixed image of the an~malwould be videorecorded pers commun.). for later analys~s.Best results from th~stechnique are obtained fsom transects flown during the early Coyotes have been dar-ted by use of a Cap-Chur morning haul-s (within 2 hours of sunrise) over flat, gun hmthe gsound (Ramsden et al. 1976) and from open areas. Resolution of infrared images has the air (Baer et al 1978). Dosages ranged from 8 - improved significantly in recent years and now 2 1 mgAg body weight for ketamine hydrochloride observers can drfhentrate among some specles (S (Ramsden et al 1976, Colnely 1979) and 2 mg/kg Beasom, Caesar- Klcberg Wrldl Res. Inst., unpubl body weight for phencyclidine hydrochloride (Bailey data). 197 1). Both dlugs have a wide margin of safety, were easily administered by syringe, and took effect Mo\vever, the FLIR te~hnic1ueIS not without its typically within 5 minutes Recovery time for problems Tenain, radiated heat fsom the ground or drugged coyotes can take up to 30 minutes (Pond other environmental heat sources, and canopy cover and O'Gal-a 1994). can obscurc images (G. Henrcke, Caesar Kleberg Wrldl Res. Inst., pers conm). ~t the present time, Nellis (1 968) described a technique of chasrng FLIR technology has not progessed to a point where coyotes with motorized toboggans until they tired. it appears practical to use to assess coyote At this point the coyote could be easily abundance. ove~po\vei-ed, however, he still advised using caution to avord lnjury to all pal-ties concerned. The Catch-rrlark--r.elease: This technrque typically use of ATVs could replace motorized toboggans in involves mult~plecaptures of lnd~vidualcoyotes. areas that lack sufficient snowfall. However, this During the inrtial captwe the coyote must be technique appears to be limited to areas of open niamta~nedalive, aRer which, subsequent collections ten-a~n which offer greater maneuverabilrty to can be by lethal means. Coyotes have been live- motorized vehicles. Death or disability can result caught by foot-hold traps, snares, boxtraps, and from capture myopathy associated with over- tranquilizer darts exeltion by the coyotes, especially in warm and hot conditions. Turkowskr el al. (1 984) described improved foot-hold traps which resulted in coyote capture rates Clark (1 972) estimated coyote density using a of over 84% and excluded smallel-, non-target modlficatron of the Petersen estimate (Bailey 1951) predators. Skinner and Todd (1 990) reported that He located active coyote dens, eartagged the pups, foot-hold traps resulted In a 3-fold greater. coyote and then 11-appedcoyotes In the same area several capture rate than foot snares Public opposition to months later The proportion of eartagged coyotes among the total number of pups captured was used Coyotes preferentially use secondary roads as travel to estimate the density of coyote pups. This lanes (Andrews and Bogess 1978), thus causing an procedure appeared to yield a sellable density upwal-d bias In density estimates. However, if estimate, but it was vely label- intensive. coyotes were routinely hunted fiom vehicles at night, a leaned aversion to vehicles and roads could result, The major problem with catch-mark-release resulting in underest~mation of coyote density. estimators is that recovely rates of tagged coyotes is Factors which Influence animal activity might also typically low (Andelt et al. 1985, Windberg and influence counts, Including time of day, season, Knowlton 1990). Gionfsiddo and Stoddalt (1 988) weather conditions, and condit~onof roadside cover. repo~tedthat coyotes marked with ear tags and vinyl Therefore spotlight surveys as an enumerat~on collars were recovered at rates of 21% and 25%, technique for coyotes should be viewed with respectively Recove~yrates increased to 50% if skepticism until the behavioral biases are assessed. coyotes also were equipped with radio collars; however, telemet~yequipment often can be cost prohibitive. Wlndberg and Knowlton (1 990) Relative abundance indices demonstrated that coyotes are seldom captured in the areas they fi-equent most and are usually captured on Catch-pel.-uiiit eSfooi.t: A variety of catch-per-unit the edges, or well outside their usual haunts. effort ~nd~ceshave been used with carnivores in general and coyotes in pasticular. Many of the Radio~sotopema-kess have been used as a trapping techniques descr~bedabove also could be means to circumvent low recovely rates. Individual used as long as capture effort is recorded. Despite coyotes are intramuscularly Injected with garnrna- whether effort is measured in man-years (Cain et al. emtting radioactive ~sotopes,which eventually gets 1972, Wagner 1972) or individual "unit-nlghts" excreted (Pelton and Marcum 1975, Knowlton et al. (e.g., trap nights) (Clark 1972, Knowlton 1972), 1989) The proportion of marked to unmarked feces standardization of procedures remains a major can be used to constluct a population estimate. problem, pa~ticularlywith regard to the manner in Estimates derived fiom these procedures appear to which different individuals use or set equipment. be quite reliable, especially ~fthe marked animals B~asesresult~ng fi-om the use of various types of are equipped with sadlo transmitters to assess the equipment as well as unequal capture vulnerab~l~ty degree to which the animals remain on the survey of animals wlthln varlous population segments need area, but this technique is labor intens~ve to be addsessed (Windberg and Knowlton 1990).

Spotliglit col(nts Spotlight counts have been used Most catch-per-unit-eKo~ttechniques are labor to estimate wh~te-talleddeer (Ha~~vellet al 1979) intensive and many have the added disadvantage of and lagomo~phs(Kllne 1965, Fafaman and Whyte modifying the population by removing individuals 1979). Few attempts have been conducted to Removal methods have been employed to estlmate ennumerate coyote populat~ons by th~smethod relative coyote population size (Henke 1992). This (Henke 1992). Spotl~ghtsulveys should begin 1 estimator IS based on the assumption that more hour after sunset and should be conducted several animals are caught during the initial effort and that times duling the same moon phase and under similar the number of captures declines with subsequent weather conditions The number of replicates effo~ts(Zippin 1958). However, the more ~ntensive depends upon the variab~lityanlong counts as well the capture effort in relat~onto the size of the area, as the precision desired. Two obse~verswith the geater the potential impact upon the population 300,000-candlepowel- spotlights and a driver are being enurnel-ated Also, coyotes quickly immigrate required to count coyotes along each roadside. The to areas where te~ritorialvacancies occur. Henke vehicle should maintam a speed of approximately 10 (1992) noted that coyote density returned to pre- mph during the survey removal levels in less than 3 months after the removal effort Rapid recolonization rates can Coyote denslties are obtained by dividing the confound removal estimators number of coyotes obsel-ved by the visible acreage. Henke (1992) believed that this method Scent statrot1 vrsitatrot~rates: Coyote visitation sates overestimated the coyote population in West Texas, to altilicial scent stations probably have been the but stated that coyote populations could be positively most widely used, standardized method for index~ng or negatively biased by their use of secondary roads. coyote abundance. Scent station indices also have been evaluated more critically than any other from wild coyotes (Alcorn 1946, Wenger and technique for indexing coyote abundance (Linhal-t Cringan 1978, Okoniewski and Chambers 1984). and Knowlton 1975, Roughton and Bowden 1979, Locations for attempting to elicit coyote responses Roughton and Sweeney 1982). This technique are identified along predetermined routes at spaclngs employs a series of kansects, each composed of a set generally greater than 2 5 miles. The routes are of regularly-spaced stations 39 inches (1 m) in usually driven between dusk and dawn and the diameter The ground sui-face is scarified and number of stations with responses, or the number of smoothed so that animal tracks can be recognized. responding groups per station, is used as the Powdered clay soils are preferred for building measure of relative coyote abundance. stations. Several factors have been identified which may Typ~cally,stations are spaced at 550 yard influence the rate at which coyotes respond, intervals with consecutive stations located on irrespective of coyote abundance. Carley (1 973) alternate sides of a road The basic sampling unit is obta~neda 4-fold difference in response rates to 3 a 3 mile line containing 10 stations. A standard types of sirens used to elicit the response. He also artificial olfactory attractant is placed In the center of noted a bimodal response pattern during nocturnal each station. Attractants have included plaster-of- sampling, with an absence of response in the middle paris disks impregnated with a scent (Roughton and of the n~ght when animals were not active. Sweeney 1982) or histology ttlssue capsules Okoniewsh and Chambers (I 984) did not detect any containing scented-cotton (I-Ienke 1992) Stations apprec~able difference between response rates are typically set out 1 day and examined the next to ellcited by siren and human voice but they d~dnote, dete~minethe number 01' stat~onsthat have been as did Quinton (1976) and Laundre (1981), a visited by coyotes. The indes of abundance nolmally seasonal pattern in coyote responsiveness. is espresscd as Among penned coyotes, it seems that an~mals (No. stalior?~w~tli co,vote visits) not associated with "terntorial groups" do not ...... X 1000. respond to other coyotes and likely would not (No. ope/-ablestations) respond to other sounds that no~mally elicit vocalizations. Camenzind (1 978) and Bowen (1 98 I) suggest similar behav~oraldifferences among Coyote bchavior can affect the number of wid coyotes. This suggests that transients within a "vis~ts".Hams (1 983) found that coyotes are more coyote population might be excluded from the l~kelyto visit scent-stat~onswhen they were away enumeration process. fi-om areas with wh~chthcy were famil~arthan when they were within familiar arcas. Andelt et al. (1 985) In addition to variable responsiveness on the suggested that prcvious advci-sc esperiences, such as part of coyotes, a var~ctyof envit-onmental factors having been trapped, reduced scent-station including topography, vegetat~onheight and dens~ty, visitations by coyotes. Fagre et al (1 983) suggested relative hunlid~ty,wind veloc~ty,air temperature, and that coyotes may become habituated to specific lures presence or absence of temperature inversions can if they are repeatedly exposed to it; however, influence the range over wh~chcoyote responses can changing lures could elicit a different response. bc dctected (Wolfe 1974) Potentially differential auditoly aculty among obsavers could also pose Env~ronmentalfactors such as strong winds, significant b~ases precipitat~on,and frozen ground, and biotic factors such as grazlng livestock and vehicular traftic can Scat depos~t~onrates Th~stechnique appears to be render scent-stat~onsunusable. Fag~eet al. (1981) one ofthe more practical because it (a) requires only noted that young coyotes were more attracted to one obsei-ver with minimal training, (b) can odors than adults; therelore, unequal vulnerabil~ty accumulate info~mation over a period of time could result in b~as. without an obseiver in attendance (Clark 1972), and (c) does not require an artificial behavioral response Elicited liowlir~g /.espor?ses: Sirens, bugles, on the part of the coyote. Davison (1980) and broadcasting recorded coyote howls, human Stoddart (1984) have used the number of coyote iniitat~onsof coyote howls, and a variety of other scats deposited along 1.0 mile segments of sound stimuli have been used to el~citresponses unimproved road In a specified period of time to depict trends in coyote abundance. Each transect is did not yield satisfactory estimates. Juveniles walked at the beginning of the sample period and all represented the majority of coyotes killed on the scats detected are removed Subsequently the highway, suggesting a strong age bias. Differential transects are walked again at a later date and the vulnerability to vehicular traffic was also reported by number of scats recovered per mile per day is used Windberg and Knowlton (1 990). Average vehicle as an index to coyote abundance. speed, weather, season, and location of preferred areas may present additional biases (Downing Balcomb (unpubl. data) indicates biases 1980). associated with this technique include: (I) removal of scats may slightly reduce the number of scats Ha~vestquestionnaires and bounvpaynrents. Many deposited in subsequent days; (2) scat persistence is agencies use harvest data from questionnaires to inversely related to the amount of vehicular traffic; estimate coyote population trends (Krause et al. and (3) failure to detect scats while walking the 1969). However, these data are subject to biases transects. About 30% of the scats were missed, ansing 60m sample size, pelt prices, and honesty of independent of observer, each time a transect was respondents. Krause et al. (1969) suggested that walked, with some indication the problem was many hunters reported they were hunting coyotes greater on transects with fewer scats. This bias can only if they happen to kill one, thus overestimating be reduced by walking transects twice, once in each coyote harvest by underestimating effort. County direction. Also, seasonal changes in scat abundance bounty systems may overestimate relative coyote may result from differentla1 scat production abundance because coyotes may be collected fiom associated with d~eta~ychanges (Andelt and Andelt nearby counties, but hunters may clalm the kill 1984), suggesting comparison of scat depos~tion occurred in the jurisd~ction paying the highest rates should not be made across seasons. bounty.

Standar.dized track counts. Establishing standard track counting areas may have the potential for being Conclusions the most I-ellable technlque for detel-min~ngrelative coyote abundance. In most situations it probably Developing techniques to assess the relative or also entails the most work. This method consists of absolute numbers of wild animals is an intriguing counting the number of fresh coyote tracks detected but complex process. In the case of the coyote, 2 within set distances of road. In snow, sand, or soft techn~ques seem to have particular merit for earth it may be I-elalivelyeasy, but on rocky or hard assessing rclative abundance: scent-station visitation substrates it may be neai-ly impossible. Todd and rates and scat deposition rates In addition, practical Keith (1 976) used liesh snowfall and Beasom (1 973, density estimates seem feasible through use of 1974) used the sandy soils of South Texas to their radioisotopes for long-te~mmarking of feces of advantages. However, environmental conditions, specific animals. However, reasons for enumerating vehicular traffic, and unworkable substrates make a population, situations at hand, and resources widespread use of this technlque impractical. available should be assessed before a technique is selected. Road-killed coyotes. The number of coyotes killed by vehicles can be used, if standardized, to estimate Before engaging in any attempt to detect trends relative abundance of coyotes. Henke (1 992) drove or changes in coyote abundance, thought should be the same 30 miles of highway roads evely day for 2 devoted to the sensitlvlty required of the estimator. weeks each season and recorded the number and How large or small a difference In abundance that locat~onof freshly-killed coyotes. He estimated the can be detected w~llbe a function of (1) the relative relative abundance of coyotes fi-om the equation, response level of Ihe particular index being used, (2) variation ~nherentin the index method, and (3) the sampling effort. Little can be done about variation inherent in an indexing technique except to rigidly where: n = number of fi-esh road-k~lledcoyotes; l = adhere to standardized methods, not only in terms of length of the road (km) surveyed; and V = average procedures but also to the conditions under which daily volume of traffic. the methods are performed. The relative level of response presumably IS a function of the number of However, f1enke (1 992) reported this technique animals present, and cannot be changed artificially, but expectations of the response rates to be , J.C. Hood, and J. R. Cain. 198 1. The effect encountered pe~mitadjustments in the sampling of stsip width on helicopter censusing of deer. J. intensity to achieve the degrce of sensitivity desired. Range. Manage. 34.36-37. In short, the quality of "the answer", in te~msof precision and accuxacy, is closely related to the effort Bowen, W.D. 198 1. Var~ationin coyote social involved and the relative scale of that particular organizat~onthe influence of prey size. Can. J. enumeration data. ZOO^. 59:639-683.

Cain, S.A., J.A. Kadlec, D.L. Allen, R.A. Cooley, Literature Cited M.G. Hoinocker, A.S. Leopold, and F.H. Wagner. 1972. Predator control - 197 1. Report Alcoin, J.R. 1946. On the decoying of coyotes. J. to the Council on Environmental Quality and the Mammal. 27: 122-1 26. Dept. of Inter., Univ. M~chPress, Ann Arbor. 207pp. Andelt, W.F. 1985. Behavioral ecology of coyotes in South Texas Wildl. Monogr. 94: 1-45. Camenzind, I;. J. 1978. Behavioral ecology of coyotes on the National Elk Refuge, Jackson,

-> -> and S.H. Andelt. 1984. Diet bias in scat- Wyoming. Pages 267-293 in M. Bekoff, (Ed.), deposition rate sulveys of coyote density Wildl. Coyotes: b~ology,behavior, and management. Soc. Bull 12:74-77. Academic Press, NY.

, C.E. Ha~is,and F.F Knowlton. 1985. Prior Carley, C.J. 1973. Development of coyote census trap experience might bias coyote responses to techmques. Presented at Colorado Chapter, The scent stations Southwest Natural 30:3 17-3 18. Wildl Soc and Colo Sec. Soc. Range, Manage., Englewood, CO. Andrews, R.D , and E.K. Boggess. 1978. Ecology of coyotes In Iowa. Pages 249-265 M Clark, F W. 1972. Influence ofjackrabbit density Bekoff, (Ed.), Coyotes: b~ology,behavior, and on coyote population change. J Wildl. Manage. management. Academic Press, New York. 36'343-356.

Baer, C H , R.E. Severson, and S.B. Linhart. 1 97 8. Comely, J.E. 1979 Anesthesia of coyotes with Live capture of coyotes from a hellcopter with ketamine hydrochloride and xylazine J. Wildl. ketamine hydrochloride J. Wildl. Manage. Manage. 43,577-579. 42:452-454 Crabtree, R L , F.G. Buston, T.R. Garland, D.A. Bailey, N T J. 195 1. On estimat~ngthe size of Cataldo, and W.H. hckasd. 1989. Slow-release mobile populat~onsfi-om recapture data radioisotope as individual markers for carni- B~ometrika38.293-306. vores. J. Wildl. Manage. 53:949-954.

Bailey, T.N.197 1. Immobilization of bobcats, Davison, R.P. 1980. The effects of exploitation on coyotes, and badgers with phencyclidine some parameters of coyote populations Ph.D. hydrochloride. J. Wildl. Manage. 35347-849. Thesis, Utah St. Univ., Logan. 120pp.

Balser, D.S. 1965. Tranquilizer tabs for captul-ing Downing, R.L. 1980. Vital statistics of animal wild casnivores. J Wildl. Manage. 29: 438-442. populations Pages 247-268 in S.D. Schernnitz, (Ed ), Wildlife management techniques manual. Beasom, S L. 1973 Ecological factors affecting 4th ed., The Wildlife Society, Bethesda, MD. wild turkey reproductive success in South Texas. Ph.D Dissert. Texas A&M Univ. Fafaman, K.li., and R.J. Whyte 1979. Factors 2 15pp. influencing nighttime roadside counts of cottontail rabbits. J. Wildl. Manage. 43:765- . 1974. Intensive sho~t-tarnpredator removal 767. as a game management tool. Trans. Am. Wildl. Nat. Resource Cod 39:230-240. Fagre, D.B , B.A Butler, W.E Howard, and R. Kline, P.D. 1965 Factors influencing roadside Teranishi 1981 Behavioral responses of counts of cottontails. J Wildl. Manage. 29:665- coyotes to selected odors and tastes. Pages 966- 671. 983 in J.A. Chapman and D. Pursley, (Eds.), Worldwide Furbearer Conf. Proa, Frostburg, Knowlton, F F. 1972. Preliminary interpretations of MD. coyote population mechanics with some management implications. J. Wildl. Manage , W.E. Howard, D.A. Bamum, R. Teranishi, 36369-382. T H. Schultz, and D J. Stern. 1983. Criteria for the development of coyote lures Vertebr. Pest , L.C. Stoddart, R.L. Crabtree, and J.W. Blatt. Control and Manage. Mater. 4:265-277. 1989. Evaluation of some radioisotopes as marking agents for monitoring bait con- Foreyt, W. J., and A. Rubenser. 1980 A live trap for sumption Pages 52-62 in K A. Fagerstone and multiple capture of coyote pups from dens. J. R D. Curnow, (Eds.), Vertebr. Pest Control Wildl. Manage. 44:487-488. and Manage. Materials. 6th Vol., Amer. Soc. Test. Mater. Publ. 1055. Gamer, G.W., J.A. Mom son, and J.C. Lewis 1978. Mortality of white-tailed deer fawns in the Krause, G.F., F W. Samson, and J M Orr 1969 Wichita Mountains, Oklahoma. Proc Southeast. Biased coyote harvest estimates: a paradox J. Assoc. Game and Fish Comm. 30:493-506. Wildl Manage 33 444-446

Gionfriddo, IP., and L.C. Stoddart. 1988 Laundre, J W 1981. Temporal variation in coyote Comparative recovery rates of marked coyotes. vocalization rates J Wildl. Manage. 45:767- Wildl. Soc Bull. 16 310-311 769.

Gutheiy, F S , and S.L Beasom. 1978 Effective- Linhart, S.B , and F.F. Knowlton 1975. Determin- ness and selectivity of neck snares in predator ing the relative abundance of coyotes by scent control. J. Wildl Manage 42:457-459 station lines. Wildl. Soc Bull 3119-124

Hamlin, K.L., S.J. Riley, D. Pyrah, A.R. Dodd, and , G.J. Dasch, and F.J. Turkowski. 1981. The R.J. Mackie. 1984. Relationships among mule steel leg-hold trap: techniques for reducing foot deer fawn mortality, coyotes, and alternate prey injury and increasing selectivity. Proc Vertebr species during summer J. Wildl Manage. Pest Conf 3:1560-1578 48 489-499. Nellis, C.H 1968. Some methods for capturing Harris, C.E. 1983 Differential behavior of coyotes coyotes alive J Wildl. Manage. 32:402-405 with regard to home range limits. Ph.D. Diss., Utah State Univ , Logan, UT. 120pp. , and L B. Keith. 1976. Population dynamics of coyotes in central Alberta, 1964-68. J. Wildl. Harwell, W.F , R L Cook, and J.C. Barron. 1979 Manage. 40389-399. The spotlight count method for surveying white- tailed deer in Texas Texas Parks and Wildl. Okonievvski, J.C, and RE Chambers. 1984 Dept Fed Aid Proj. No. W-109-R. FA Rep. Coyote vocal response to an electronic siren and Serv No. 21. 25pp. human howling. J. Wildl. Manage. 48:217-221

Henke, S E. 1992 Effect of coyote removal on the Pelton, M.R., and L C. Marcum 1975 The faunal community ecology of a short-grass potential use of radioisotopes for determining prairie Ph.D Dissert , Texas Tech Univ., densities of black bears and other carnivores. Lubbock, TX. 229pp Pages 221-236 in R.L. Phillips and C Jonkel, (Eds), Proc. Predator Symp., Mont. Forest Jotham, N., andR.L Phillips. 1994. Developing and Cons. Expt. Sta., Univ Mont., Missoula. international trap standards - a progress report Proc. Vertebr. Pest Conf. 16-308-310.

77 Pond, D.B , and B.W. O'Gara. 1994. Chemical Todd, A W., and L.B. Keith. 1976. Responses of immobilization of large mammals Pages 125- coyotes to winter reductions in agricultural 139 rn T.A Bookhout, (Ed.), Research and ca~rion.Alberta Dcpt. Rec., Parks and Wildl., management techniques for wildlife and Fish and Wildl Drv., Wildl Tech. Bull. 5: 1-32. habitats. 5th ed. The Wildlife Society, Bethesda, MD. Tuskowski, F J., A R Armistead, and S.B. Linhart. Quinton, D.A. 1976. An evaluation of two coyote 1984 Select~vityand effectiveness of pan census techniques, Final rep., Contract No. 14- tension devices for coyote foothold traps. J. 16-0008-1 142, Texas Tech. Univ., Lubbock, Wildl. Manage. 48.700-708. TX. 3 1 pp. Wagner, F.H 1972. Coyotes and sheep, some Ramsden, R.0 ,P.F. Coppin, and D.H. Johnston. thoughts on ecology, economics, and ethics. 1976. Clinical observations on the use of keta- Utah State Univ., Logan Faculty Honor Lecture mine hydrochloride in wild carnivores. J. Wildl. 44: 1-59. Dis. 12.221-225. Wenger, C.R , and A.T. Cringan 1978. Siren- Roughton, R.D , and D. Bowden. 1979 Esperi- ellcited coyote vocalizat~ons.an evaluation of a mental design for the field evaluation of odor census technique. Wildl. Soc. Bull 6.73-76. attractants for predators. Pages 249-254 in J.R. Beck, (Ed.), Ve~tebr.pest control and manage. Windberg, L.A., and F.F. Knowlton 1990 Relative materials. Amer Soc. Test Mates. STP 680, vulnerabil~tyof coyotes to some capture Philadelph~a,PA procedul-es. Wildl Soc. Bull. 18:282-290.

, and M W Sweeney. 1982 Refinements in Wolfe, G.J 1974 Siren elicited howling response scent station nielhodolo~yfor assessing trends as a coyote census technique. M.S. Thesis, in carnivore populat~ons.J W~ldl.Manage. Colo State Univ., Folt Collins, CO 206pp. 461217-229. Zemlicka, D. E., and K B~uce.1991. Comparison Sclivner, J.H., D A. Wade, G.E. Connolly, and L.C. of handmade and molded rubber tranquilizer Howard. 1985. Cost and other effects of tabs for delivet-ing tranquilizing materials to predation on an angora goat ranch. Rangelands coyotes captured in leg-hold traps. Pages 52-56 7:54-57. in S E Hygnstrom, R M. Case, and R. J. Johnson, (Eds.), Proc. loth Great Plains Skinner, D.L , and A. W. Todd. 1990. Evaluating Wildl Damage Control Workshop, Great efficiency of footholding devices for coyote Plains Agl-ic. Council Publ 137. capture. Wildl. Soc Bull. 18.166- 175. Zippin, C. 1958 The l-emoval method of popula- Spowat, R.A., aid F.B. Samson. 1986 Cam~vores. lion estimation. J. Wildl Manage 22:82-90. Pages 475-496 111 A.Y. Coopenider, R.J Boyd, and H R Stual-t, (Eds.), Inventory and monitor ing of wildlife habitat. U S. Dept Inter., Bur. Land Manage. Setvice Center, Denver, CO

Stoddall, L.C. 1984. Relative abundance of coyotes, lagomol-phs, and rodents on the Idaho Nat'l Engrneering Lab. Ann. Rep of Pred Ecol and Beh Proj , Denver Wildl. Res Ctl-. Denver, CO. 24pp