Dispersal and Mortality of Red Foxes Author(s): R. L. Phillips, R. D. Andrews, G. L. Storm, R. A. Bishop Reviewed work(s): Source: The Journal of Wildlife Management, Vol. 36, No. 2 (Apr., 1972), pp. 237-248 Published by: Allen Press Stable URL: http://www.jstor.org/stable/3799056 . Accessed: 06/02/2012 09:10 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact firstname.lastname@example.org. Allen Press is collaborating with JSTOR to digitize, preserve and extend access to The Journal of Wildlife Management. http://www.jstor.org OF REDFOXES AND MORTALITY DISPERSAL lowa ConservationCommission,Boone1 R. L. PHILLIPS, lowa ConservationCommission,ClearLake R. D. ANDREWS, G. L. STORM,Departmentof Ecologyand BehavioralBiology, Universityof Minnesota,Minneapolis R. A. BISHOP,lowa ConservationCommission,ClearLake Abstract: Duringthe periodfrom 1963 to 1968, 926 red foxes (Vulpes fulva) were capturedat dens ear-tagged,and releasedat the pointsof capturein IowaandIllinois. Tag returnsfrom367 markedfoxes provideddata concerningdispersaland mortality.Somejuvenilesapparentlybegin to dispersefromie natalareain late Septemberand earlyOctober.The averagestraight-linedistancesbetweenreleasesites and recoverysites were 18.4 miles and 6.2 milesfor 171 juvenilemalesand 124 juvenilefemales,respectively. Fourteenjuvenilemalesand one juvenilefemale were recoveredmore than 50 miles from their natalranges. Locationsof recaptureswere not randomlydistributed(P < 0.05) with respectto direction of travel. The MississippiRiverappearsto act as a barrierto foxes that disperseon eitherside of it in Iowaand Illinois. Huntingand trappingaccountedfor about80 percentof the mortalityof the foxes recoveredin this study. Annualrecoveryratesfor taggedfoxes rangedfrom22 to 44 percentin Iowa of foxes to huntingappearsto be interrelatedwith and from18 to 35 percentin Illinois. Vulnerability snowcoverand land use in localareas. Dispersal-typemovementsof red foxes havebeenreportedby ErringtonandBerry (1937), Sheldon(1950,1953), Arnoldand Schofield(1956), Longley (1962), Ables (1965), Marcstrom(1968), and Jensen (1968). Their studies provided ample evidencethatred foxescommonlymove15 to 20 milesfromtheirnatalrangesand that a few individualsdispersemore than 100 miles. Publishedreportsdo not, however, providedataon suchaspectsof dispersalas seasonaltiming,travelroutes,ratesof moveof juvenilesandadultsof ments,proportion each sex that disperse,and factorsassociated with initial and terminalphasesof dispersal. The types and extentof mortalityin fox populationsundoubtedlyvary with area, season, weathercondition,and unknown factors.Differencesin mortalityratesmay alsorelateto differencesin ratesof dispersal in localregions.To ourknowledge,no one has undertakenan intensivestudy of the natureof mortalityin redfox populations. This paper presents preliminarydata 1 Present address: Bureau of Sport Fisheries and Wildlife, Forestry Sciences Laboratory, Missoula, Montana. concerningdispersaland mortalityof red foxesin Illinois,Iowa,andMinnesota. This study was financedby the Iowa by NIHTraining Commission, Conservation andby theU. S. GrantNo.5 TO1GMO1779, (CO0-133246) AtomicEnergyCommissilon directedby Dr. J. R. Tester. Preliminary work in Illinois was supportedby PHS GrantNo. CC00047directedby Dr. G. C. Sanderson,IllinoisNaturalHistorySurvey. We acknowledgethe cooperationof farmers, conservationofficers,and game managerswhoassistedin locatingfox dens. We thankG. G. Good,G. F. Hubert,Jr.,G. E. Hubert,K.P. Dauphin,andE. I. Eickertfor assistancein the field, and Dr. D. B. Siniff and JudithE. Baxterfor preparingcomputerprograms.AnnH. Jones,Drs. E. D. KlonglanandR. B. Finley,Jr.reviewedthe manuscript. STUDYAREAS Fieldworkto capture,mark,and release and foses was conductedin north-central and Illinois,andnorth-central northwestern Iowa ( Fig. 1) . In northwestnortheastern ern Illinois,work centeredin Carroll,Jo Daviess,andWhitesidecounties.Thewest237 Journal of Wildlife Alanagement, Vol. 36, No. 2, April 1972 238 FOX TAGGING AREAS m m > 30 MILES < 30 MILES Fig 1. Fox tagging areas in lowa, Illinois, and Minnesota. ern partsof these countiesare includedin the Wisconsindriftlesssection of Illinois. Slopesvaryfromgentleto steep. About40 Carroll percentof the landin northwestern County is woodland ( Storm 1965) . The counties easternpartsof the northwlestern are under intensivecultivation,with relatively few woodlots. In north central Illinois,workwas donein DeKalb,LaSalle, and Kane counties. This area is characterizedby flat prairielandsused primarily is flat forintensiveagriculture.Topography to gentlysloping,and thereare fewer timIllinois. bered areasthan in northwestern North central Iowa is under intensive cultivationand the topographyvariesfrom flat to gentlyrolling.Lessthanone percent Iowa of the areais woodland.Northeastern hasgentleto steepslopes,andfarmlandsare withwoodlands.About25 perinterspersed cent of the areais in timber(Thorntonand Morgan1959). Foxeswerecapturedandreleasedin both regions: statesin two generalphysiographic in hilly areaswith mixedfarmsand woodlotswithin30 milesof the MississippiRiver, and in relativelyflat areasunderintensive cultivation,more than 30 miles from the MississippiRiver. No attemptwas made to delternlinethe relativenumbersof foxes. However,bounty recordsfromIllinoisindicatedthatfox densities were higher in countiesadjacentto the MississippiRiver than in the central counties( Mohr1947,Chiasson1953) . Further evidence for higher fox densitiesin countiesadjacentto the MississippiRiver is providedby bounty recordsfor Iowa. Bountyrecordsby countiesindicatedthat 0.8 and 2.5 foxes per square mile were bountiedfromthe northcentraland northeasternareasof Iowa,respectively(Phillips 1970) . work referredto in The radio-tracking thispaperwasconductedin CarrollCounty, Illinois,and on the Cedar Creek Natural History Area ( CCNHA) in east central Minnesota.The latter area has been describedby Pierce( 1954),Brayet al. (1959), and Rongstadand Tester( 1969) . METHODS The basic methodused was to capture, mark,and releasefoxes at dens duringthe springwhen litterswere restrictedto denning sites. The date and locationof the for each originalcapturesite wererelcorded tagged fox. Later,the date, location,and method of kill were recordedfor each markedfox reportedto projectpersonnel. Computerfacilities at the Universityof Minnesotawere used to aid in analysisof the data. Foxeswere foundduringthe April-June periodby locatingactivedens reportedby officers,farmers,hunters,and conservation trappersfamiliarwithlocaldens;by searching fromgroundandair;andby requesting, conthroughlocalnewspapers,information pups were sites where fox cerning den present. Foxes were chased from dens with the use of a mechanicalwireferret( Stormand Dauphin 1965) . Some foxes were pulled REDFOXES* Philltps et al. 239 out of denswhen theirbody hairsbecame Table 1. Distances in miles between first and last capturesof red foxes tagged as juvenilesand recoveredduring entangledin the wire;otherswere caught their first year of life. by hand or with a dip net when they MALES FEMALES emergedfromthe dens. Steeltraps( Nos.1 MONTH Number Mean Number Mean and2) placedat orneardensitesfor 1 or 2 RECAPof Distance of Distance TURED Animals Traveled Animals Traveled nights were used to capturea few foxes thatwerenotchasedfromdensby ferreting. April 2 0.0 5 0.0 14 0.4 5 0.1 Afterbeingmarked,eachfox was returned May June 10 0.7 7 0.8 to the denwhereit wascaptured. July 7 1.6 1 0.9 Metal tags were placed in the ears of August 4 2.5 4 0.9 1.1 1 1.6 each fox. Two typesof tags were used: a September 1 October 8 14.8 6 2.0 No. 681 monelmetal tag (NationalBand November 27 25.4 20 7.8 and Tag Co., Newport,Kentucky)and a December 38 21.1 27 7.8 48 25.8 32 9.0 button tag ( Nasco, Inc., Fort Atkinson, January February 11 20.8 14 4.8 Wisconsin).Tags were stampedwith the March 1 51.5 2 10.8 appropriateidentificationso that an indi- Total 171 124 vidualwho killeda taggedfox wouldknow Mean 18.4 6.2 whereto sendthe recoveryinformation. Radio transmitterswere attachedto 8 juvenilefoxes in Illinois and 23 juvenile were tagged in Illinois and 631 in Iowa. foxesin Minnesotato determinewhenthey Tag returnswere obtainedfrom367 foxes left the natal area. The equipmentde- by June 1969. These data providedthe scribedby Storm(1965)wasusedto monitor primarybasis for determiningthe initial radio-taggedfoxes in Illinois,and similar periodof dispersal,ratesof travel,distances trackingdeviceswereusedto monitorfoxes anddirectionsof travel,andmortality. in Minnesota( G. L. Storm,unpublished Dispersal data). In thispaper,a movementof overS miles Initialdispersalof juvenilefoxes appar( airline distance) between the point of ently occurredduring late Septemberor originalcaptureand the recoverysite is early Octoberwhen most juvenileswere considereda dispersal-type movement.The about 7 monthsold. Our data indicated arbitraryfigure of 5 miles is based on that juvenileswere still in the areaof the reportedevidencethatsizesof homeranges natalden at leastthroughAugust(Table1). of nondispersingred foxes are less than In September,only two taggedfoxeswere S miles in diameter( Scott 1943:443444, killed an averageof 1.4 miles from their Storm1965, Ables 1969, Sargeant1972) . nataldens. Dataobtainedfromradio-trackThe juvenileage-class(l-year or less) for ing of foxes also gave no evidenceof disthis study is from the month of birth persalbeforeOctober.Noneof six juvenile throughMarch31 of the followingyear. foxes (five malesandone female) carrying functionalradioslefttheirnatalareasbefore RESULTS October1 in Illinois,and 23 juvenilefoxes A total of 926 red foxes (899 juveniles ( 10 malesand 13 females)radio-tagged in and 27 adults) were captured,ear-tagged, Minnesotastayed in their natal ranges and releasedat or neardens duringApril- throughOctober1 (G. L. Storm,unpubJuneof 1963through1968. Of these,295 lisheddata). 240 Journal of Wildlife Management, Vol. 36, No. 2, April 1972 site; anotherwas killed November25, approximately99 miles from his natal area AINE DISTANCE (Table 2). Both movedover 90 miles in SEX BETWEENNATAL (ALL RANGEANDPOINT less than 60 days, assumingthey did not JWEDATE OF RECAPTUREa NILES) OF KILL (MILES) leave the natalrangebeforeOctober1. One juvenilemale in Illinoiswas moniMale toreddailywithradioequipmentuntilradio October12 14 October19 39 contactwas lost October23, 1966. Thisfox October28 45 was killedDecember10 by a trapper7 100 November 6 57 milesfromits birthplace(45 daysafterhe November 8 95 November10 72 was last locatedon the natalrange). Female Anotherradio-taggedjuvenilemale that November11 27 dispersed from ie CCNHAin Minnesota November24 26 traveledan averageof 11 miles per night Male November24 54 in one directionduringa S-dayperiodin November25 99 November(G.L. Storm,unpublished data). November29 46 This distance is approximately equal to the a All movements were made in less than 8 weeks, assuming that onset of dispersal occurred after October 1. distancetraveledin 1 night by a resident fox in familiarrange in late fall ( A. B. ). If The onset of dispersalappearedto be Sargeant, personal communication earlierin malesthan in females. By mid- dailymovementsof about11 milesin one October,somejuvenilemaleshad traveled generaldirectionare typical of red foxes more ian 20 miles from the natal areas. duringdispersaldistancesof 100 miles or EightmalesrecovereddunngOctoberhad moremayeasilybe attainedduringperiods traveledan averagedistanceof 14.8miles, of less fqan 1 month. ccympared with 2.0 miles for six juvenile The recoverydistancesof juvenilemales in thisstudyrangedfrom0.0 to 101.2miles, femalesrecoveredduringthis period. Differencesin onsetof dispersalbetween with a meanof 18.4milesand a medianof sexesmaybe relatedto seasonalchangesin 10.1miles ( Fig. 2 ) . Morejuvenilefemales reproductive activityof foxes. Venge(19S9) than juvenilemales remainedin or close reportediat malesweresexuallymaturein to the natal rangesduringthe first year late Novemberand December,whereas ( March31) . Eighty-twopercent of the femalesdid not begin estrusuntilJanuary juvenilefemalesrecoveredin theirfirstyear or February. McIntosh( 1963) reported were within10 milesof theirnatalranges. thatthe testesof malefoxesbeganincreas- Recovery distancesfor juvenile females ing in size about 3 monthsprior to the rangedfrom0.0 to 52.1miles,with a mean height of ie breedingseason,but ovaries of 6.2 miles and a median of 2.2 miles of femalesbeganto increasein size about (Fig. 2). 1 monthbeforethe peakbreedingperiod. The tendencyfor more males than feData conceiningthe dailyrate of kave malesto leavetheirnatalareaswas evident of dispersingfoxeshave not been reported for both young-of-the-year and 2-year-olds in the literature.Two of the juvenilemales (Table3 ) . Forty-nine( 78 percent) of 63 in the studytraveledmorethan90 milesby juvenilemalefoxesrecoveredin Iowa dur3ateNovember.One was killedNovember ing 196869 were takenmorethan5 miles 8 approxim-ately 95 miles fromthe release fromtheirnatal ranges. Vuringthe same Table 2. Long-distancemovementsby juvenile red foxes recoveredduringOchber and November. REDFOXES* P/l illi ps et al . 24 1 their first year of life and remainedthere untiltheydied. Whetherdispersalas adults was relatedto dispersalduringtheir first year of life was not clear. Radio-tracking studiesof foxes ( Storm196S,Ables 1969) showedno evidenceof dispersalby adults duringspringand summer.Thissuggested ffiatadults,like juveniles,dispersedduring tn 70the fall andwinter. o Informationon the directionof travel duringdispersalwas providedby plotting o the recoverylocationsfor foxesthatmoved ILI SOm more than S miles from their respective 2 N = 295 pointsof release.Thedataanalyzedto date z 40* MALES indicatedthat the kill locationswere not a FEMALES randomlydistributed(P < 0.05) with respect to directionof travel. For example, 26 67 and 57 percentof the foxes recovered 20| in Iowa and Illinois, respectively,were killednorthof theirrespectivereleasesites (Table 4). A similartendencyis evident fromthe datareportedfor Michiganfoxes by Arnoldand Schofield(1956), and for 0-}0 11 20 21-30 3l-40 41-so s>*o 61+ DISTANCETRAVELED(AIR MILES) foxesin NorthDakota(Donahoo1962). The higher proportionof tagged foxes Fig. 2. Distoncesbetween first and lost copturesfor male killed north of the points of releasemay and female foxes recoveredwithin the first year of life. reflecta tendencyfor a generalnorthward movement of red foxes, but evidencefor period, 22 of 23 2-year-oldmale foxes such a migration wasnotconclusive( Butler ( taggedin 1967)wererecoveredmorethan 1951, Macpherson 1964). Anotherreason S milesfromtheirnatalranges.The higher proportion,among adults, of long-range may be the relationshipbetweenweather of foxesto movements wasalsoevidentamongfemales conditionsandthe vulnerability hunting pressure. For example, foxes may (Table 3). These data indicatedthat not all foxesset up permanent residenceduring be morevulnerablein areaswith abundant X L 60- 30- | nL1 X Table 3. Proportionof lowa foxes recoveredmore than 5 miles from their natal ranges during the period of OctoberMarch,196K69, 1 and 2 years after tagging. YEAROF TAGGING 1968 1967 a b AGE SEX Young-ofthe-year 2-year-oldb Male Female Male Female NUMBEROF FOXESRECOVERED TOTAL NUMBER S Miles More Than RECOVERED or Less 5 Miles 63 45 23 12 14 30 1 6 49 15 22 6 RANGEa 6.0-63.0 6.0-52.1 7.0-97.0 25.0-43.5 Upper and lower limits of recovery distances for foxes that moved more than 5 miles from their natal ranges. About 1.5 to 2.0 ye;lrs old. 242 Journal of Wildlife Management, Vol. 36, No. 2, April 1972 Table 4. Directionol distributionof recoveries for foxes that traveled more than 5 miles from their natal ranges. TAGGING NUMBEROF ANIMALS ARAENADNE DIREC- (OO_ TION 90°) Iowa Illinois North South NW (971°360°) SE (91°180°) SW (181°270°) CHI_ SQUARE VALUE 59 10 26 16 20 7 25.02** 8.64* 16.70** 36 21 126 69 . ADJACENT TO RIVER AWAY FROM RIVER Northcentral * Significant ( P < 0.05 ) . * * Significant ( P < 0.01 ) . snowcover. Sincesnowwas morefrequent in regions north of our study areas, the higherproportionof foxes killed north of releasepointsmay reflecthighermortality ratesratherthan greaterratesof dispersal towardthe north. Except for the higher proportionof recoveriesnorthof releasepoints,the distributionof recoverylocationsin the northcentralcountiestendedto be randomlydistributed. A differentpatternwas evident for animalstagged in countiesadjacentto the MississippiRiver (Fig. 3). Therewas Northwestern lowa Illinois Fig. 3. Comparativepattern of dispersal for foxes tagged and released in north-centrallowa (more than 30 miles from MississippiRiver) and foxes tagged in northwestern Illinois (less than 30 miles from MisssisippiRiver);interval between concentriccircles equals 20 miles. Dots are placed according to direction of travel; center of circle represents tagging site. no evidenceof tagged foxes crossingthe MississippiRiveralongtheIowaandIllinois boundaries,and it appearedtha,tthe river served as a barrierto dispersalof foxes. Theriverin thisareais generallynotfrozen duringNovember,but slomeyears it may be frozen and coveredwith snow by late Decemberor earlyJanuary. Table 5. Numberof red foxes recoveredwith respect to types of mortality,lowa and Illinois. AGE AND SEX Juvenileb Male Female STATE NUMBER RECOVERED (ALL YEARS) MORTALITY TYPE Hunting Trapping Road-kills Miscellaneousa Iowa 118 84 71 (61) 57 (66) 28 20 250 22 (19) 10 (11) 7 (6) 5 (6) 18 (15) 12 (14) 24 (86) 12 (60) 164 (66) 3 (11) 6 (32) 41 (16) 1 (3) 1 (5) 14 (6) 1 (5) 31 (12) 53 40 25 (47) 22 (55) 17 (32) 12 (30) 8 (15) 3 (7) 3 (12) 3 (7) Male Female Subtotal 16 8 117 7 (44) 4 (50) 58 (50) 5 (31) 5 (50) 38 (32) 1 (6) 3 (19) 12 ( 10) 9 (8) Total 367 222 (60) 79 (22) 26 (7) e Adultd Male Female Subtotal Juvenileb Male Female Illinois Adultd 40 (11) Includes pups found dead at dens, killed at farln buildings, killed by farm machines, and dead from unknown causes. Young-of-the-year through March 31 of the following year. 2 Percentage given in parentheses. d Older than young-of-the-year. a b RED FOXES* P7>illipset al. 243 Table 6. Numberof juvenile foxes killed by monthwith respect to type of mortality. KILLED NUMBEROF FOXES Hunting Trapping Miscellaneousa Road-kills TOTAL MONTH Males Females Males Females Males Females Males Females January February March April May June July August September October November December 42 11 4 1 2 1 2 8 25 30 14 2 1 1 2 12 17 6 3 17 13 2 3 7 10 1 3 6 2 3 - 1 2 1 3 1 - 2 10 7 2 - 5 4 5 1 - 80 25 3 7 19 17 8 8 2 14 47 65 Total 96 79 39 22 15 8 21 15 295 RECOVERIES (27)b (7) ( 1) (2) (6) (6) (3) (3) ( 1) (5) ( 16) (23 ) Includes pups found at dens, those killed at farm buildings and by farm machines, and those dead from unknown causes. b Percentage of total recoveries in parentheses. a Thefactorsassociatedwith dispersalpat- tions concerningthe influenceof environterns in mammalsare not well known. mental factors on dispersalof red foxes haveimplicatedexternal remainunanswered.We feel that these Someinvestigators causativefactors,such as high population problemsdeservefurtherstudy. of habitat,or both levels or deterioration 1963:78).Otthers Mortality (Elton1927:146,Errington have suggestedinternalcausativefactors, The data presented here concerning suchas changinghormonelevels,as partof mortalityare based entirelyon reported the stimulusfor long-distancemovements mortalityassociatedwith the taggedfoxes (Slonaker1924,1927,Cahn1925,Howard recoveredduringour study. The relative 1960,Beer and Meyer1951). Manyques- importance factors,such of naturalmortality Table 7. Recoveryrates of juvenile male and female red foxes. Numberin parenthesesis percentage recovered. NUMBEROF FOSESTAGGED TAG- DURING NUMBERRECOVERED FIRSTYEAF(OF LIFE YEAR Males Females Males Females 1966 1967 1968 39 128 166 40 107 137 17(44) 29(23) 70(42) 18(45) 23(22) 46(34) 333 284 116(35) 87(31) 68 22 56 48 16 43 21(31) 3(14) 18(32) 19(40) 4(25) 14(33) Subtotal 146 107 42 (29) 37 (35) Total 479 391 158(33) 124(32) AREA Iowa Subtotal Illinois 1966 1967 1968 944 Journalof WildlifeManagement,Vol. 36, No. 2, April1972 Toble 8. Vulnerabilityof juvenile and adult red foxes to hunting and trapping (vulnerobilitymeosured by year-oftagging recoveries). YEAR-OFFOXES TAGGING RATIOOF TAGGED RECOVERIESRECOVERY RATE ADULTTO JWENILE JuveJuveJuveVULNER_ Adults niles Aduks niles Adults niles asILITYt 14 617 3 155 21.4 25.1 1: 1.17 Vulnerability quotient or index = juvenile recovery rate/adult recovery rate = 1.17. 8 Table 9. lowa. Tag recoveries by two geogrophic regions in TAGGING REGION NUMBER NUMBER PERCENTOF FOXES RECOV- AGERETAGGED ERED COVERED Within 30 miles of Mississippi River 54 10 19* More than 30 miles from Mississippi River S77 236 41* * Rate of recoverywas significantlydifferent (P < 0.05). as diseases,parasites,and accidentsother than those associatedwith man, was not determined. Hunting and trapping acoountedfor about80 percentof the mortalityof foxes recovered(Table 5 ) . These results are similarto thosereportedby Jensen(1968) andMarcstrom ( 1968). Eighty-twopercent of the reportedmortalityoccurredfrorn SeptemberthroughFebruary.Trappingof foxes was done primarilyduringOctober, November,December,and January.All of the trappedfoxes were reportedlykilled duringthesemonths(Table6). SomefoxeswereshotduringOctoberand November,andit appearedthatthe taking of these animalswas incidentalto other huntingactivity.Fox huntingin Iowa and IllinoisoccurredprimarilyduringDecem- ber and Januaryas was reflectedby the high numberof tagged foxes reportedly shot duringDecemberandJanuary(Table 6). Moremales than femaleswere killed by huntingand trapping,but the differenceswerenot significant(Table7). The slightlyhigherrecoveryof malesmayreflect theirhigherdispersalrateandgreatertravel n untamlllar range. Seventy-twofoxes were recovered as adults(olderthanyoung-of-the-year), and only three of these were reportedlykilled on roads. One adultwas reportedlykilled by farm machines.These data indicated thatmortalitydueto carsandfalmmachines was not an importantfactor affecting markedadultred foxes. The rateof kill on roadwayswas higher r .1 . Table 10. Numberand percentogeof foxes recovered1-3 years after tagying. STATE Iowa YEAR OF TAGGING Total FOXESRECOVERED DURINGb Year 1 Year 2 1966 1967 1968 79 235 303 617 35(44) S2(22) 116 (38) S(6) 36(1S) 0 1966 1967 1968 116 38 99 253 40(35) 7(18) 32 (32) 3(3) 6(16) 0 Total Illinois NUMBERa TAGGED Year 3 TOTAL 2(3) O ° 42(53) 88(37) 116(38) 246 (40) 0 ° 0 43(37) 13(34) 32(32) 88(35) Tagged and released where captured as pups. Number in parentheses is the percentage recovered after spring tagging; year 1 is from time of tagging through March 31 of next year; year 2 is from April 1, 1 year after tagging through March 31 of the next year; and year 3 is from April 1, 2 years after tagging through March 31 of the next year. a b REDFOXES* Phillips et al. 245 Table 11. A comparisonof fox tag recovery rates from different areas. LOCATION REFERENCE Iora New York Michigan Russia North Dakota Sweden Denmark Iowa Illinois Erringtonand Berry (1937) Sheldon(1950) Arnoldand Schofield(1956) Tchirkova( 1955) Donahoo( 1962) Marcstrom( 1968) Jensen ( 1968) This study ( 1966-68) This study ( 1963-68) NUMBEROF FOXES TAGGED 236 120 37 126 179 163 17S 631 295 RECOVERY RATE ( PERCENT ) 7a 33 54 21 25 36 31 40b 39b aFoxes b tagged in this study were transported from natal dens to other release sites. Includes recoveries to June 1969. for juvenilesthanfor adultfoxes. Seventy- the sameforjuvenilesandadults.Ourdata fourpereentof thismortalityoeeurreddur- indicatedthat juvenileswere 1.17 times ing June,July,and August(Table 6). In more vulnerableto huntingand trapping thesemonths,juvenilefoxeswerebeeoming thanadults(Table8) andwere 1.54times less restrietedto denningsites and were morevulnerablethanadultswhenall types likely to cross roads during exploratory of mortalitywereconsidered. movements.It is probablethatsometagged The rateof mortaliity of foxestaggedand foxeswerekilledon roadwaysandwerenot recoveredin areasover 30 milesfromthe reportedto us. Thefur of road-killed foxes MississippiRiver appearedto be higher is of no value duringthe summermonths, (P < 0.05) thanthatfor foxestaggedand and road-killedanimalswere generallynot recoveredwithin 30 miles of the river handledby man. Some foxes hit by cars (Table 9). Evidencefor lower mortality may be throwninto ditehesby the impact ratesin the hilly and morewoodedlands and remainineonspieuousto man. Thus, adjacentto the riverwas providedby agewe believe our data underestimatedthe structuredata (Phillips1970) thatshowed importanee of this type of mortality. adult:juvenile ratios of about 1:2.6 for Differeneesin vulnerabilityto hunting northeasternIowa and 1:5.6 for central and trappingbetweenjuvenilesand adults Iowa. Whether differencesin mortality were ealculatedby modifieationof a for- betweenphysiographic regionswererelated mulapreparedby Bellroseet al. (1961:435). to differencesin natality,incidenceof disWe assumedthat the rateat whiehhunters eases,hunting,trapping,farmingpractices, and trappersreportedmarkedfoxes was andweatherconditionswas not clear. Table 12. The relationshipof winter huntingconditionsto recoveryrates, pelt prices, and fox harvestsin lowa, 1966-68. WINTER PERIOD NUMBEROF JUVENILE FOXESTAGGED DURINGSPRING 1966-67 79 1967-68 23S 1968-69 303 aData compiled in cooperation PERCENTAGE RECOVERED 44.3 21.1 38.3 DAYSaW1TH CUMULATIVEa >2 INCHES AVERAGE SNO\FALL ACCUMULATION PELT (INCHES) OF SNOW PRICE 25.6 11.5 44.2 50 6 97 $5.80 $4.12 $10.39 FOX FURS SOLDTO IOWA FUR BUYERS 13>072 10,688 27,661 with the U.S. Department of Commerce, the Iowa Department of Agriculture, and the Ioxva Weather Bureau at Mason City, Iowa. 246 Journalof WildlifeManagement,Vol. 36, No. 2, April1972 About30 percentof the foxestaggedas juvenileswere recoveredduringthelirfirst year (Table10). Annualrecoveryratesfor taggedjuvenilefoxesrangedfrom22 to 44 percentin Iowa and from18 to 35 percent in Illinois(Table 10). Obviously,not all foxes killed by man were reported. We know of entire unreportedlitters of markedfoxes killed at den sites. Three unreportedtagged foxes were also foundduringexamination of fox pelts sold to fur dealers.Recoveryratesof taggedfoxes in this studywere similarto thosereportedby previousworkers(Table tionof foxesthatdisperse,iPtis obviousthat dispersalis a majorinfluenceaffectingthe populationdynamicsof red foxes. Knowledge of dispersalof foxes should be an importantoonsideration whendealingwith the epidemiologyof diseases associated with foxes, diseasecontrolprograms,programsdesignedto reducenumbersof foxes, managementof foxes for economicand recreationaluse, and evolutionlary studies of foxes. Currently, thereis littleknownaboutthe relationshipsbetween dispersaland incidence of diseasesin foses. Someworkers 11). have suggestedthat an increasein rabies Recoveryrates in Iowa appearedto be in foxesduringthe fall-winterperiodmay relatedto weatherconditionsfavorablefor be associatedwith the time of dispersal huntingduringwintermonths.Snowcover ( Muller1966,Pitzschke1966,Ulbrich1967, wasabundantin thewintersof 196S67 and Friend 1968) . Recent data presentedby 198W69yearsmarkedby highfoxharvests JohnstonandBeauregard (1969)forOntario andrecoveryrates(Table12). Duringthe showedthat 66 percentof the rabidfoxes 196748 wintertherewas littlesnowon the in late summerandfall weremalesand 65 Iowa studyareas,and a relativelylow re- percenitof the maleswerejuveniles.Since coveryratewas experienced. dispersalappearsto be more intensivein Mortalit,v in foxeswas associatedwith a malesthanfemales,thepotentialforcontact complexset of factors. Mortalitydue to betweenfoxesis higherfor malesthanfor hunting appearedto be related to the females,and therebymay accountfor the amountof annuial snowcover,anddifferent differencesin the incidenceof rabiesbemortalityrateswerenotedbetweenphysio- tween sexes. However,the role of behavgraphic regions. Thus, vulnerabilityof ioralisolatingmechanisms in the transmisfoxes to man appearedto be interrelated sion of rabiesbetweensexes is unknown withsnowcoverandlanduse in localareas. (Johnstonand Beaureglard 1969). Programsto reducefox numbersin the DISCUSSIONAND CONCLUSIONS north-centralUnited States do not seem ltis study indicated-iat approximatelyfeasible,and perhapsthey are not justified 70 percentof the markedand recovered at this time. Vertsand Storm(1966) rejuvenilemale foxes moved more than 5 portedthaitred foxes were neitheracting miles from thelirnatal rangesduringtheir as reservoirsof rabiesduringthe pre-epifirst year. This figure increasedto over 200ticperiod,nor contributingto the in90 percentif the males survivedanother fections among striped skunks ( Mephitis year. About 30 percentof ffie recovered mephitis)duringthe epizooticof the disjuvenilefemalesdispersedmorethan5 miles ease in Illinois. in their first year, and the proportioninWith the high rate of interchangebecreasedto 50percentif thefemalessurvived tween local populationsbecause of disanotheryear. In view of the high propor- persingfoxes,it is apparentwhy programs REDFOXES* Phillips et al. 247 ) designedto flow, and ultimatelyon the evolutionof (such as bounty payments redueefox numbershave generallyfailed redfoxesin the Midwest,is notfullyunderto meettheirobjeetives.Evenif loealpop- stood. Furthertaxonomicsltudiesof foxes ulationsare markedlyredueed,the vaeant shouldbe a fertilefield forfutureresearch. areasbeeomerepopulatedwiithin1 yearby foxes moving in from surroundingareas. LITERATURE CITED Ourdatashowthatmanyfoxestraveled20 ABLES,E. D. 196S. An exceptional fox moveto 40 miles to oceupynew rangesduring ment. J. Mammal. 46 ( 1 ): 102. 1969. Home-range studies of red foxes theirfirstyear. ) . J. Marnmal.50 ( 1 ): 10S120. ( Vulpes It may be that undercertaineonditions, ARNOLD,D. vulpes A., AND R. D. SCHOFIELD.1956 new techniquesshouldbe developedand ( 1955 ). Home range and dispersal of Michigan red foxes. Michigan Acad. Sci., Arts, and used undereloselysupervisedprogramsto Letters Papers41(pt. 2):91-97. reducenumbersof foxesin loealor regional BEER, J. R., ANDR. K. MEYER. 1951. Seasonal areas. Our data suggest that appropriate changes in the endocrine organs and behavior patterns of the muskrat. J. Mammal. 32(2): eontrol measuresmay be most effeetive 173-191. duringthe late winterandspringwhenthe BELLROSE, AND A. S. HAWKINS, F. C., T. G. SCOTT, numbersof foxesare at an annuallow and J. B. Low. 1961. Sex ratios and age ratios in North American ducks. Illinois Nat. Hist. whellfew, if any,foxesaredispersing. Survey Bull. 27 ( art. 6 ): 391474. Furtherevideneeof the eeonomieimpor- BRAY, ANDL. C. PEARSON. J. R., D. B. IAWRENCE, tance of foxes is providedby our data 1959. Primaryproductionin some Minnesota terrestrial communities for 1957. Oikos 10 showingthatman,by huntingandtrapping, ( pt. 1 ) :3S49. aeeountedfor 80 pereentof the reported BurLER, L. 1951. Population cycles and color in Illinois foxes, Red mortality. taggedfox phase genetics of the colored fox in Quebec. Canadian J. Zool. 29(1) :24-41. and Iowa, offer reereationalopportunities CAHN,A. R. 1925. The migration of animals. throughsporthuntingduringthe periodof Am. Naturalist 59 (665): 539-556. late Decemberthrough February,when CHIASSON,R. B. 1953. Fluctuations of some Illinois fox populations. Ecology 34 (3): 617most other game hunting seasons have 619. elosed. Foxhuntingmaybeeomestillmore DONAHOO, D. G. 1962. Fox tagging study, North attraetiveto huntersin futureyearsin the Dakota. U. S. Bur. Sport Fisheries and Wildl. 12pp. Mimeo. UnitedStatesif the numbers north-eentral C. 1927. Animal ecology. Sidgwick and of o!thergame animalsdeeline. A sound ELTON, Jackson, Ltd., London. 207pp. managementpoliey eoneerningred foxes ERRINGTON, P. L. 1963. Muskrat populations. The Iowa State UniversityPress, Ames. 665pp. shouldeonsiderthis speeies,not only as a , ANDR. M. BERRY. 1937. Tagging studpredator,but as an importantgameanimal. ies of red foxes. J. Mammal. 18(2):203-205. We eoneludethat,withthe existingpopula- FRIEND,M. 1968. History and epidemiology of rabies in wildlife in New York. New York tions of man and foxes,the sporthunting Fish and Game J. 15(1):71-97. of foxes shouldbe eneouraged.We agree HOWARD, W. E. 1960. Innate and environmental dispersal of individual vertebrates. Am. 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Wildl.Mgmt.34(1) :52-56. for use in studies of foxes and skunks. J. PIERCE;, R. L. 1954. Vegetationcovertypes and Wildl.Mgmt.29( 3 ):625-626. land use historyof the CedarCreekNatural TCHIRKOVA, A. F. 1955. Tagging foxes. CanHistoryReservation,Anokaand IsantiCounadianWildl.Serv.,Translations RussianGame ties, Minnesota.M.S. Thesis. Univ. of MinReports3( 1958) :208-214. nesota. 137pp. THORNTON, P. L., ANDJ. T. MORGAN.1959. T11e PrrzscKE,H. 1966 (1965). Epizootiologyof forest resourcesof Iowa. U.S. Forest Serv., rabies in Europe. Internatl.Symp. Rabies, CentralStates Forest Expt. Sta., Forest SurSymposia Ser. Immunobiol.Standardization vey Release22. 46pp. 1:231-236. ( S. Karger,Baseland New York.) ULBRICH, F. 1967. Uber regelmafiigkeiten beim RONGSTAD, O. J., ANDJ. R. TESTER. 1969. Moveauftretender tollwutim BezirkDresden: ein mentsand habitatuse of white-taileddeer in beitragzur epizootologieder tollwut. Archiv Minnesota.J. Wildl. MgInt.33( 2 ):36S379. fur ExperimentelleVeterinarmedezin 21(4): SARGEANT, A. B. 1972. Red fox spatialcharac1073-1084.( RussianandEnglishsummaries. ) teristicsin relationto waterfowlpredation.J. VENGE,O. 1959. Reproductionin the fox and mink. Animal BreedingAbstr. 27( 2 ): 129Wildl. Mgmt. 36(2):225-236. 145. SCOTT,T. G. 1943. Somefood coactionsof the northernplains red fox. Ecol. Monographs VERTS,B. J., ANDG. L. STORM. 1966. A local study of prevalenceof rabies among foxes 13(4) :427-479. and stripedskunks.J. Wildl.Mgmt.30(20): . 1955. An evaluationof the red fox. 419421. IllinoisNat. Hist.SurveyBiol.Notes35. 16pp. SHELDON,W. G. 1950. Denning habits and Received forpublication April30,1971.