ll ' I l . 1‘ l 91‘ w 1 f: N | w l r I \ 1 —‘l (A) _I H: [ I \J N H‘ (I) 01 \1 ~' i“ 32:45: 95:22:: NATEOH 3.7? macaw: {Eaggvow 2.07m LENNAEUSE nan-n- mv - 11133‘ '54”. ‘ 732mg {m- i‘ha Dogma cé M. 3-. M3CHIGAH STATE UN Robe-r1“ Arnold Sunde” SKY h, II III llllll “I II“ III llllll III! II “II" II "II Illlll lll Ill III” II 3 1293 10306 3198 £1.11 ”’9 13“" I: AGE DETEMENATION STUDIESOF m RACCOON (PROCYON LOTOR LINNAEUS) BY Robert Arnold Sundell AN ABSTRACT Submitted to the College of Agriculture of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Fisheries and Wildlife 1956 Approved fffé .7 .m V This study consisted of two phases: the investigation of (1) growth of first-year animals, and (2) age criteria of fall-caught animals. Growth of the humerus, radius and ulna-was studied in X-rays of captive specimens between two and 30 months of age. measurements of maximum length seemed to offer a basis for estimating the ages of young animals and also for separating the 0.5 and 1.5 year classes among fall-caught specimens. The hump erus, radius and ulna of a 0.5 year old animal measured 90, 89 and 109 milli- meters, respectively, while comparable measurements of a 1.5 year old animal were 101, 100 and 118 millimeters. The weights of eight juvenile wild raccoons on first capture and when la- ter killed were used to estimate their ages based on the growth curve present- ed by Stuewer (l9h3). Three of the estimated birth dates (May 26, June 3 and 25) were later than Stuewer's latest date. As Stuewer also observed, the growth of most wild raccoons evidently is slower than that of captives. In fall-caught Specimens, skull characteristics (rostral suture closure, tooth wear and sagittal crest development), shape and texture of the baculum, length and epiphyseal fusion of the foreleg bones were combined to separate four age classes: 0.5, 1.5, 2.5 and older-than—2.5 years. On 13 skulls of 0.5 year old animals, all the sutures of the rostrum were distinct. On the skull of one 1.5 year old animal, all the rostral sutures were distinct except the nasofrontal and nasopremaxillary sutureS'which were nearly fused but still discernible as indistinct lines. On five specimens 2.5 years old or older, all the rostral sutures were nearly or completely fUSed. The molar cusps of 13 skulls of 0.5 year old specimens were sharp while those of one 1.5 and one 2.5 year old specimens were rounded or slightly flat- tened. 0n four specimens more than 2.5 years of age, the molar cuSps were much worn and nearly or completely level with the intercusp tooth surfaces. Sagittal crest development was variable but in general the 0.5 year old male specimens exhibited temporal ridges which were fairly straight, approxi— mately parallel and flattened against the temporal bones. In the 1.5 year old specimen, the ridges were curved, wider than the 0.5 year olds at the point of maximum width, constricted just anterior to the lambdoidal crest and raised from the temporal bones. In the specimen 2.5 years of age, the ridges were straight, raised one to two millimeters from the temporal bones and nearly joined to form the sagittal crest characteristic of all older male specimens. The bacula of five 0.5 year old specimens possessed small proximal ends with minutely-perforated surfaces and cartilaginous ligaments on the distal ends. The bacula of five specimens 1.5 years old and older exhibited enlarg— ed proximal ends with roughened surfaces while the cartilaginous ligaments were absent. . The degree of epiphyseal fusion of the bones of the foreleg, studied on cleaned bones and in X—rays, was defined as none in 0.5, partially fused in 1.5, and fused in specimens 2.5 years old and older. Application of the skull criteria to a sample of 109 unknown-age wild specimens gave the following results: 0.5 years, 8h; 1.5-2.5 years, 17; old- er-than—2.5 years, 8. AGE DEEERlflNATION STUDIES OF THE Raccoon (PROCYON LOTOR LINNAEUS) By Robert Arnold Sundell A THESIS Submitted to the College of Agriculture of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Fisheries and Wildlife 1956 TABLE OF CONTENTS W‘OGNO‘O‘O‘WUWNHH LIST OF TABLES AND GRAPES 11 LIST OF FIGURES m “ iii ACENOILENEIIDITS ___ iv INTRODUCTIQI Previous Investigations hterials Available _ GRCITH OF FIRST-YEAR ANIMALS ~ A Growth of Leg Bones ——— Isights and Birth Dates AGE CRITERIA OF FALL-CAUGHT ANIMALS -—--- Slcull Characteristics ——— Suture closure Tooth wear — ~— Temporal ridge and sagittal crest development All slmll criteria —- n w Characters of the Baculum Epiphwseal Fusion of Leg Bones —— 10 Other Characters ~ 12 COMBINED DATA FOR HALF-YEAR CLASSES 12 SUMMARY === _ l2 FIGURES .1 ~ A —— 15 23 LITERATURE CITED “ Table l. 2 . 3. Graph 1. LIST OF TABLES AND GRAPHS Leg Bone Measurements from Known-Age Raccoons Page 1: Dates of Epiphyseal Fusion of Leg Bones of Known-Age Raccoons ---- 11 Multiple Key for Age Determination in the Raccoon ——— Growth of Tagged Juvenile Wild Baccoons in Central Michigan 1h Figure 1. 2. 3. h. 5. 6. 7. LIST OF FIGURES Skulls of one-half year old and one and one-half year old P880 captive Isle raccoons — Skulls of one-half year, one and one-half year and two and 17 one-half year old captive male raccoons I-rays of the forelimbs of a captive one-half year old ——18 raccoon —— ‘v I-rays of the fore- and hindlimb of a captive one and one- —19 half year old raccoon X-rays of the fore- and hindlinb of a captive two and one- ~—— 20 half year old raccoon —~ — Proinal end of humerus of one-half, one and one-half and two and one-half year old captive raccoons ——~ Distal end of femur of one-half, one and one-half and two and one—half year old captive raccoons iii ACKN OWLENEMEVTS The author expresses gratitude to Dr. George A. Petrides, Associate Professor, Department of Fisheries and Wildlife, Michigan State University, for many suggestions and for guidance throughout the study and for supplying X-rays, skeletons and skins of animals of known age. Dr. C. T. Black of the Game Division of the Michigan Department of Conservation provided several known-age skulls, a number of unknown-age skulls and weight data for several retrapped raccoons. Jerry Werbelow, owner of Jerry Werbelow Hides, Furs and Wool, of Alma, Michigan, donated 109 skulls. Roswell D. Van Deusen, Director of Michigan State University's Kellogg Bird Sanctuary, Aelred Geis, Instructor, Department of Zoology, Michigan State University, Jack Mall, Michigan State University undergraduate student and Merl lemon, Lansing, Michigan, raccoon hunter, also provided useful specimens. Drs. Don Hayne, John Cantlon and Rollin Baker, all of the Michigan State University faculty, read the manu- script and offered suggestions. 4' INTRODUCTION The raccoon (.Procm lotor Linnaeus) is an important game and fur animal througiout most of its range in the United States. In the stuw of population dynamics of any species, the ability to identify age classes is essential. The purpose of this study was to evaluate and refine methods used in age determina- tion in the raccoon. Previous Investigations Several workers have investigated age criteria in this species. Stuewer (l9h3) presented growth curves indicating that young-of-the-year attain full ear length by August and full hind foot length by December. He separated fall juveniles from adults by weight. Adults were identified as those weighing over 11: pounds. Unworn upper canine teeth indicated immaturity to him, while well worn teeth characterized an adult three years or older. Petrides (1950) found that the adult baculum was characterised by a pro- nounced basal enlargement with roughened surfaces not present in first-year juveniles. He also found that I-rays of the forepaws of both sexes revealed fusion of the distal epiphyses of the radius and ulna with their respective diaphyses by the third year. Complete fusion of the proximal epiphyseal plate was noted in the humerus of a four-year old. Thus, in males, using bacula and forepaw epiphyses together, first-year, second—year and older animals could be identified as such. For females, tests of those which had bred were found to be enlarged, dark and wrinkled while teats of females which had not bred were swell, pinkish and smooth. Since only about 50 per cent of one and one—half year old females breed (Stuewer, 19113), however, these criteria even in com- bination with I—rays, did not permit the certain separation of first- and second- year females. Sanderson (1950) found the presence of unossified cartilage on the distal end of the baculun to be characteristic of first-year juveniles. He used a body weight of 15 pounds in male adult-juvenile separation and found it to be 90 per cent accurate. Dellinger (19514) reported that the most useful aging criterion of the baculum was the condition of the basal end which was described as porous in juveniles and well ossified in adults. His conclusions regarding weight paralleled those of Sanderson (1950). Materials Available Materials utilised in the study included complete skeletons and skins of six captive, known-age male specimens from the Raccoon Farm of the Ohio Depart- mnt of Natural Resources at Milan, Ohio. These specimens were 0.5, 1.5, 2.5, 5.5, 7.5 and 9.5 years old at the time of death. There were two additional specimens (0.5 and 1.5 years old) from Chic with skulls lacking. Twenty-five I-rays of the leg bones and bacula of the known-age Ohio specimens were avail- able. Thirteen skulls of known-age (12 six-months old and one 8.0 years old) wild animals and 12h skulls from mknown-age, wild specimens were secured from populations in central Michigan. ‘ The skeletons of the eight known-age, captive specimens were cleaned by dermsstids. The skulls of the 13 known-age and 15 of the tmknown-age, wild ani- mals were cleaned by maceration and dermestid action during outdoor exposure in a wire cage. The 109 skulls from caresses of fur animals were studied in the flesh. GROWTH OF FIRST-EAR ANIMALS Growth of Leg Bones The lengths of a humerus, radius and ulna of a captive male specimen were measured from I-rays at 2, 6, 10, 12 and 30 months of age. ' Measurements also were ands of the bones of two additional specimens 18 months old. These lengths are given in Table l and seem to offer a basis for estimating the ages of young animals and also for separating at least the 0.5 and 1.5 year classes among fall- caught specimens. Further investigation of variability, however, is desirable. v.1 ghts and Birth Dates Eight Juvenile wild raccoons were handled twice each at the Rose Lake Hild- 1ife Experimt Station near Lansing , Michigan. Their weights on first capture and when later killed by hunters were recorded by Station personnel. These weights were plotted on the growth curve for three captive juveniles presented by Stuewer (1910) and ages and birth dates were estimated. Five of the estimat- ed dates fell within the seasonal extremes listed by Stuswer (from the first week of April to the second week of May) but three (May 26, June 3 and 25) were later than his latest date. Either the actual breeding season is longer than determined by Stuewer or the animals concerned (numbers 2, h and 6 of Graph 1) underwent their early development at a slower rate than Stuewer's captives and appeared younger at first capture than they actually were . Since the recapture Table 1. Leg Bone Measurements from Known-Age Raccoonsl Length in millimeters Source Age in months Humerus Radius Ulna X-rayz 2 76 72 85 I-ray2 6 903 89 109 X-ray2 10 97 96 116 X-ray2 12 98 97 116 Bone sh 18 101 100 118 Bones 13 103 ' 102 120 I—ray2 30 106 102 120 1 The bones of only one foreleg from each animal were measured. 2 Measurements from successive X-ray negatives of the same captive animal. 3 A close approximation from an X-ray in which the entire tip of the bone did not show on the plate. it An I-ray also was available; measurements from the X—ray and from the bones were identical. L ( 0 (:3 [hi (‘1 LG C \ rd C) C J r. If. \£ (— 5: UN LN (”H H ('3 ‘1 ‘U\ L r—’ C,“ O U\ C“ C \L 1M <’ ) (' x 1 r‘ oma n ma .pmmm .m moeanmmo m.hesmasm ,- so me :0 npsoao OCCH Q. : _ E to u om .pmwm .o H T Is I )-J .p 10 srzm .m ooom NHH I mm .pmow .: 2 e cma I mm .pmew .m . sl 1 3.4)) a. med mo .+;u, .m a N 000m mm 1 a anew .H mm i n: mi mm cw ore campmmo w an vopmfiflwwm pmhwm mo ewom m cm Mm coo: Wm H cm .awmflnoflm Heapsmo ca mcoooomm UHflE maflcmbsw nommma mo gasses .H gamma coco Doom s l k C 11/ .}~‘ r: weights of these particular individuals were quite close to those expected from Stuswer's curve, however, it seems likely that they actually were born late in the season near the dates indicated. is Stuswer also observed, the growth of most wild raccoons (Graph 1) evidently is slower than that of captives. AGE CRITERIA OF FALL-CAUGHT ANIMAIS According to Stuswer (1913), most raccoons are born during April and May. Some possibly are born in June (see above). The age characteristics described beyond are presumed to be most useful in aging animals taken during fall hunt- ing and trapping seasons, about six months or 0.5 years after birth. Skull Characteristics Skull characters investigated on 19 known-age specimens were closure of the sutures of the rostrum, wear of the teeth, and developmnt of the temporal ridges and sagittal crest. 922353. closure 3 In the 13 known-age young-of-the-year (approximately 0.5 years old), all the rostral sutures were distinct (Figure l). m the only known 1.5 year old specimen, the nasofrontal and nasopremaxillary sutures were nearly fused but still discernible as indistinct lines. as specimens 2.5, 5.5. 7.5, 8.0 and 9.5 years old, all of the rostral sutures were fused except that sev- eral millimeters of the anterior portion of the internasal suture were open in the 7.5 aid 8.0 year old specimens. The nasopremaxillary suture was present as an indistinct line as the 5.5 and 7.5 year old skulls. Of all the rostral sutures, the man110premaxillary was thought to be most reliable in separating 0.5 year old from older specimens. 01 all 13 skulls of half-year old animals, this suture was distinct mile on the cranium of the 1.5 year old specimen, it was fused but present as an indistinct line (Figure l). 01 all five specinns of animals older than 1.5 years, it was completely fused and not evident. A possible indication of the age of fusicm was found in a wild specimen aged by leg bone length as nearly ten months old. The manllopremaxil- lary suture was fused but still ev ident as an indistinct line. The rostral area of the skull must be scraped or cleanedto permit use of this mthod. 392251325: The reliability of the tooth wear differences in captive specimens is uncertain. According to E. D. Martin of the (hie Division of Wildlife (per- sonal letter), the raccoons studied at the Raccoon Farm in film, mic, were fed a mash diet composed of a variety of ground meals and neat scraps. Dr. nar- tin believed that there was less wear on the teeth of the game farm raccoons than would be true of raccoons feeding on a coarser natural diet. That this is likely true was borne out by a comparison of the 9.5'year captive skull with the 8.0 year wild one , wherein there was considerably more wear on the younger wild specimen. Some useful age differences in tooth wear seemedto prevail, however, in the younger age classes. None of the 13 skulls of half-year old animals showed any evident wear on molar or preeolar teeth. The tips of the canines were sharp. Slight wear was obsemd on the inner surfaces of the mandibular canines but could not be used to differentiate age classes. The characteristic most useful in identifying age classes seemed to be the degree of wear of the molar cusps. The molar cusps of the skulls of 0.5 year old specimens were sharp whereas they were flattened or rounded on the specimnswof 1.5 and 2.5 year old animals. 0n specimens of ani- male older than 2.5 years, they were worn aid nearly or completely level with the intercusp tooth surface (except for the anterior lingual paraconid cusp of the last mandibular molar which.remainsd elevated). The mandibular molars of the specinn 2.5 years old exhibited less wear than those of the 1.5 year old animal. All. four specimens older than 2. 5 years had the canines much blunted and oftentappsrently broken naturally. Degree of tooth wear was combined'sith rostral suture closure and sagittal crest development to separate skulls into three age classes: 0.5 years, 1.5-2.5 years, and older-than-2.5 years (see Table 3). Temporal £E§£E.§E§;E§Eifital crest development: The development of the temporal ridges and.sagittal crest was too varied to be useful by themselves in separa- ting age classes. lhen combined with rostral suture closure and tooth wear, however, these criteria were helpful. 0n the 13 skulls of half-year old ani- mals, the temporal ridges were fairly straight, approximately parallel and flat- tened against the temporal bones. The outer margins were seven to nine milli— meters apart at the point of mm width. 01 the skull of a 1.5 year male, these ridges were curved, 16 millimeters apart at the point of maximum width and constricted just anterior to the lambdoidal crest (Figure 2). The ridges were slightly raised from the temporal bones. On the skull of a 2. 5 year old male, the ridges were straight, raised one to two millimeters from the temporal bones and nearly joined to form a sagittal crest. Sagittal crest development in fe- males may not paralled that of males. The skull of'the 8.0 year old female em- hibited temporal ridges similar to the type observed on 0.5'year old male speci- mens. Unfortunately, only the one knownrage female skull was available beyond the first-year class. _A_l_:_l._ s__kul_J_. criteria: In applying these criteria to a sample of 109 skulls of wild unknown-age specimens, the age classes and numbers determined were 0.5 years, 814; 1.5-2.5 years, 17; older—than-2.S years, 8. Theoretical kill fig- arcs of a population of 109 based on a regular annual 20 per cent survival rate would be: 0.5 years, 87.2; 1.5 years, l7.h; 2.5 years, 3.5. The differ- ences between the two sets of data were not significant (P - .01) according to chi-square tests. The large number of specimens identified as older than 2.5 years may reflect an increasing survival rate in older raccoons or a se- lectiveness in the sample (favoring the larger and hence older animals by trappe rs ) . Characters of the Baculum The size and shape differences of the baculum reported by Petrides (1950) were evident in the sample of six known-age bacula, although a rather striking exception was observed. This was the baculun of a 0.5 year old animal which showed moderate enlargement of the basal end. In an X-ray of the series of six known-age bacula, however, the penis bone of this 0.5 year old animal appeared to possess a hollow, or at least unossified, basal and while the bacula from older animals were solid. This X-ray and the baculum of the 0.5 year old speci- men also exhibited cartilage on the distal end as reported by Sanderson (1950). It was not as evident on the cleaned specimen, however, as on five fresh bacula from animals which were classified as 0.5 years old according to all other cri- teria utilized in this study. These five bacula all possessed small basal ends while five bacula of 1.5, 2.5, 5.5. 7.5 and 9.5 year old animals exhibited pro- nounced basal enlargements. The cleaned baculum of a 0.5 year old raccoon ex- hibited a proximal end which was covered with minute perforations. This agrees with Dellinger's (1951;) description of the pmn‘mal end of the Juvenile (ap- parently referring only to first-year animals) baculum as “porous". Five clean- ed bacula from specimens 1.5, 2.5, 5.5, 7.5 and 9.5 years old possessed roughen- ed proximal ends as described by Petrides (1950). Epiphyseal Fusion of leg Bones Progressive fusion of all epiphyses of the long bones was investigated in both X-rays and cleaned bones. In two X—rays and four cleaned bones of two specinns 0.5 years old, the opposing margins of the diaphyses and distal epi- physes of the radius and ulna were distinct and unfused. They appeared as a double line. Corresponding X—rays and bones of 1.5 and 2.5 year old specimens showed the cartilaginous epiphyseal plate as an indistinct double line (par- tially fused) and as an indistinct single line (fused), respectively. No con- starrt bone differences within the 2.5 year and older specimens were noted. The single indistinct line of separation apparently usually persists. Pstrides (19- 50) also found no definite differences in the ossification of the distal epiph- ses of the radius and ulna between specimens three to four years old and those ten and eleven years of age. Figures 3, h and 5 and Table 2 provide some details of X-ray differences inthe distal epiphyses of the radius and ulna of 0.5, 1.5 and 2.5 year old specimens. In X-rays of a front and hind leg and in all 20 cleaned leg bones of five specinens, two 0.5, two 1.5 and one 2. 5 years old, respectively, the op- posing margins of the diaphyses and epiphyees of the proximal end of the humerus and the distal and of the femur were found to be particularly distinct (see Fig- Table 2. Dates of Epiphyseal Fusion of Leg Bones of Known-Age Raccoons. Specimen Sex Date of Birth Date of X-ray Age Degree of Epiphyseal Fusion} of long Bones 1 M Early April, 6/20/51 2 mos. None; distinct double line 1951 2 ll Early April, 10/11/ 51 6 mos. None; distinct double line 1951 3 u 24/17/50 1/16/51 8 mos. None; distinct double line 1; ll 3/21/ 50 1/16/ 51 9 mos. None; distinct double line 5 )1 Early April, 2/11/52 10 mos. None; distinct double line 1951 6 ll Early April, 14/15/52 1 yr. None; distinct double line 1951 A 7 F 3/26/h9 1/16/ 51 1% yrs. Partially fused; indistinct double line 8 M h/7/h9 l/16/51 1% yrs. Partially fused; indistinct double line 9 u h/ll/h8 1/16/51 2% yrs. Fused; indistinct single line 10 u h/l/hs 1/16/51 5% yrs. Fused; indistinct single line 11 M 1916 1/16/51 7% yrs. Fused; indistinct single line 12 ll l9hl 1/16/51 9% yrs. Fused; indistinct single line * S” text, page 100 urea 6 and 7). Other Characters Investigation of eight skeletons of known-age specimens failed to reveal any additional obvious differences between specimens of the different age clas- ses. Structures examined included processes of the vertebrae, ribs, and pec- toral and pelvic girdles. Hairs from corresponding parts of pelts from specimens 0. 5 to 9.5 years of age were mounted and neasured with an optical micrometer under the microscope. No useful differences in hair diameter were observed. COMBINED DATA FOR HALF-mill AGE CLASSES A key to age determination in raccoons, so far as suitable criteria are available, is given Table 3. SUMMARY 1. The lengths of several bones of the foreleg permitted the determina- tion of age up to about 18 months. 2. The opposing surfaces of the diaphyses and epiphyses ofthe leg bones of five raccoons, two 0.5, two 1.5 and one 2.5 years old, appeared as distinct double lines, indistinct double lines and indistinct single lines, respectively, on bones and in X-raya. 3. In general, the sutures of the rostrum were found to be distinct in 0.5 year olds, distinct except for the nasofrontal and nasopremaxillary in 1. 5 year olds, and indistinct or indiscernible in 2.5 year olds and older specimens. h. Wear on the mandibular molars was observed as lacking (cusps sharply pointed) in 0.5 year olds, moderate (cusps flattened or rounded) in 1.5 and 2.5 year olds, and heavy (cusps nearly or completely level with intercusp area) in animals over 2. 5 years old. 5. Temporal ridge developmnt was observed as flattened and approximately parallel ridges in 0.5 year old sales. In 1.5 year old ales, the temporal rid- ges were slightly raised and parallel or curved. Sagittal crests usually were present in males 2.5 years old and older. 6. The proximal end of the baculun was usually small and with a minutely perforated surface in 0.5 year old mles and enlarged and with a roughened sur- face in males 1.5 years old and older. 7. The distal end of the baculum was found to possess a cartilaginous ligament in 0.5 year old miles which was absent in all elders pecimens. A. B. C. CO. D. Table 3. Multiple Key for Age Determination in the Raccoon. Condition '0 Humerus, radius and ulna approximately 90, 89 and 109 milli- meters long (maximum length) respectively; opposing surfaces of diaphyses and epiphyses of leg bones evident as distinct double lines on bones and in X-rays; all sutures of the ros- trun distinct; no evidence of wear on mandibular molars (cusps sharply pointed); temporal ridges in male flattened and ap- proximately parallel; proximal end of baculum usually small and with perforated surface, distal end with cartilaginous hmnt ‘ttadled .0...0.0...0....OOOOOOOOOOOCOOOOOOOOOO0.0.. Not “ in A OOOOOOOOOOOOOOOO0000......OOOCOCOOCOOOOOOOOOO B Humerus, radius and ulna approximately 101;, 101 and 119 mil- limeters long respectively; opposing surfaces of diaphyses and epiphyses of leg bones evident as indistinct double lines on bones and in X-rays; sutures of rostrum open except nasc- frontal and nasopremaxillary which are evident on the skull as indistinct lines; some wear on mandibular molars (cusps flattened or rounded; never pointed except anterior lingual cusp on third molar); temporal ridges in male slightly raised from temporal bones and parallel or curved; proximal end of baculun enlarged and with roughened surface, distal end with- OUt cartilaginous ligament attached eeeeeeeeeeeeeeeeeeeeeeee NOt 38 in B eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee C Humerus, radius and ulna approximately 106, 102 and 120 mil- limeters long respectively; opposing surfaces of diaphyses and epiphyses of leg bones evident as indistinct single lines on bones and in X—rays; all sutures of rostrum usually closed; wear on mandibular molars similar to 1.5 yrs. old; sagittal crest usually present in male; baculum similar to 1.5 yrs. old N013 ‘8 in C OOOOOOOOOOOOOOO0.00.0.0...OOOOOOOOOOOOOOOOCC D Characters as in 0 except for much wear on mandibular molars (cusps nearly or completely level with intercusp area) ...... Ia. Approximate A80 6 m03e 1 yr. 6 MOSe 2 yrs. 6 m08e older than 2 yrs. 6 mos. '0. e e g e a Q ' . CW. 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Breeding season, productivity and population trends of raccoons in Missouri. M..A. Thesis, Univ. Missouri, 82 pp. (typed), 10 tabs., 6 figs. Petrides, George A. 1950. The determination of sex and.age ratios in fur animals. Amer. Midl. Nat., h3 (2): 355-382. Sanderson, Glen C. 1950. Methods of measuring productivity in raccoons. Journ. Wildl. Hgto, 1h (b): 389-h02. Stuswer, Frederick W; l9h3. Raccoons: their habits and management in Michigan. Ecol. Mom, 13 (2): 203-257. a: it “W. . 9H3 DemCOo293 -Date Due LI "Illll?!l‘l‘l‘iilll'fl'lll'“