223 SOME OBSERVATIONS OF THE MOOSE HUNT IN THE BLACK STURGEON AREA OF NORTHWESTERN ONTARIO.

Transcription

1 223 SOME OBSERVATIONS OF THE MOOSE HUNT IN THE BLACK STURGEON AREA OF NORTHWESTERN ONTARIO. H. R. Timmermann Ontario Ministry of Natural Resources Wildlife Biologist, Thunder Bay, Ontario Abstract,c Antler development, body size and eye lens weight were related to age. Moose of ages 8.5 to years generally produced the largest sized antlers as measured by three dimensions. Body measurements and weights continued to increase with age, with males being larger than females. Eye lens weights separated only calf and yearling age classes reliably. The Black Sturgeon timber cutting limits bordering the west side of Lake Nipigon is a vast area stretching nearly 150 miles' north to the town of Armstrong and south to the Trans Canada Highway #17. These limits, for many years a favourite haunt of sportsmen, represent an ideal model of timber cutting followed by regeneration and moose harvesting. The pulpwood operations that began in the late 19)0's have followed what we believe to be a progression most compatible with moose production. Although major cutting operations in the area ceased in 1965 some logging is planned to continue until 1975, generally in a scattered pattern throughout the limits. The land when disturbed by logging produces highly favourable moose habitat. The Black Sturgeon Limits (B.S.L.) is placed by Rowe in Section B9 of the boreal forest and is typical of a large area of that Section that is not under the immediate influence of Lake Superior.

2 224 Throughout the area the precambrian basic intrusive bedrock of gabbro and diabase is overlain by relatively deep glacial deposits according to Ellis (1972). To the west and south of Black Sturgeon Lake this consists mainly of water worked till. Extensive sand plains occur to the northwest. The topography is gently rolling with only occasional rock bluffs. Bedrock exposures are infrequent. In the numerous streams and rivers stretches of rapid flow alternate with sluggish sections and swampy areas. Soil parent materials vary in texture from sand to clay loam and is usually deep. Stands composed of aspen, birch, spruce and balsam fir are typical of most sites. Past logging disturbance appears to favour the development of hardwoods at the expense of the conifers. On moist sites black spruce becomes prominent and on dry sites jack pine becomes important. Although the ARDA land classification did not include this area, extrapolation of their findings would indicate a rating of high 4 or even a 3 in some sections. Access for hunting is provided by a network of main and secondary haul roads estimated at 600 miles, plus countless miles of tote roads and skid trails. Because the logging was carried out on an extensive basis, with small cuts occurring over a period of years, the roads were kept in a constant state of good repair. l-iore recently recreational funds have been spent on an annual maintenance of main and secondary arteries. Public use of the area had been controlled by a timber company gate situated 18 miles north of Highway #17 on the main Armstrong road. by permit only. During the late 1950's access was allowed The year 1965, however, marked the end of major cutting operations and hence gate control. The gatehouse was subsequently turned over to the Department of Lands and Forests (now Ontario Ministry of Natural Resources) for use as a game and fish check

3 225 station. Alternate access routes to the area were developed in 1969 and A second check station situated on the Spruce River Road (Highway #800) was subsequently established in order to monitor all hunters in the area. Records of the moose harvest have been kept since Company gate men cooperated by recording the moose kill for the period Beginning in 1966 the Department conducted an intensive study of the early season moose hunt in the area. Hunters and harvested game were monitored past the check station during the first two weeks of the season at a time when approximately 80% of the annual kill takes place. Interim.reports concerning the early season moose harvest for the area were documented by Timmermann (1966) and (1968) and Tolmie (1967). Initially check station activities were patterned after those carried out on the long established Red Lake Road Station. During the six year study many new approaches at data collection were attempted, some discarded and others retained in an overall effort to obtain factual information concerning moose hunter activities in specific areas within the B.S.L. This data includes information on hunter activity and harvest, sex and age composition of the kill, time of day and location of kill, antler development related to age, weights and measurements related to age, eye lens weight related to age, as well as specific data concerning kill locations related to access, and past logging activities. We are now specifically concerned with how long a quality hunt can be maintained under the present reduced logging operation. The purpose of this paper is to examine the data that has been collected to determine which information will be most valuable to indicate changes in the moose population or in the utilization of the resource

4 226 by hunters. All data is being collated and evaluated to be presented in a larger report. Only three of the sections will be dealt with here. Results will be reported and tentative conclusions made wherever possible. ANTLER DEVELOP~ffiNT RELATED TO AGE ***~,~,* *~,********* ******* ** *** Antlers of big game are considered souvenirs or trophies of the hunt by most sportsmen. Moose exhibit the greatest antler development of any North American big game animal. Few studies except those conducted by Cringan (1955) exist regarding moose antler development related to age. Cringan's findings related antler development to wear class age and concluded that the greatest developed antlers generally occur in the wear class Vll or 8.5 to 10 year old age category. The incisor cementum ring count ageing of bulls being transported past the check station presented an opportunity to compare actual age to antler development. METHODS All specimens were measured during the first two weeks of the fall season 1966, 1968, 1969, 1970 and 1971 at the Black Sturgeon check station. Three basic measurements were taken using a steel tape measure calibrated in 1/8 inch intervals. The beam circumference was measured on either the left or right side as most convenient and recorded. The maximum antler spread was measured between the widest points judged to touch two parallel lines drawn perpendicular to the main axis of the skull. The third criterion used in determining development tallied the total number of points on both beams over one inch long and longer than wide. The incisor cementum

5 227 ring count ageing technique as described by Sergeant and Pimlott (1959) was used to correlate antler development with age. For each age classification (1.5 to 14.5 years) each of the three measurements were averaged to the nearest 1/10 of an inch. RESULTS AND DISCUSSION Table 1 illustrates thrge moose antler measurements related to age based on 383 specimens harvested in October. Figurel further illustrates antler variability related to age, based on the total number of points more than one inch in length as well as the maximum antler spread. It was found that moose in the Black Sturgeon area, of ages 8.5 to 11.5 years, generally produced the largest development of antlers (Timmermann, 1971). A progressive increase occurred in all three measured characteristics from the age of 1.5 to 6.5 years. The greatest average maximum spread (51.3") occurred at 11.5 years of age; the greatest average number of points (19.8) occurred at 10.5 years; and the largest average beam circumference (8.2") occurred at 11.5 years. Animals older than 11.5 years showed a marked reduction in antler development. A great deal of variation occurs in antler shape and size for each age classification. No two sets are ever exactly alike. The typical antlers of a Black Sturgeon yearling have two or three points on each side; however, antlers bearing four or five and in one case, seven points on each side were recorded in the sample of 107 yearlings measured and aged. Their greatest spread varied from 14.8 to 32.0 inches with an average of 24.8 inches. Older moose show a great deal of variability and this fact makes judging the animal's age by antler growth an impossible task. Antlers from 55 moose at the age of 2.5 years, for example, ranged from a minimum of 24.8 inches to a maximum of 46.5 inch spread.

6 Table 1. Three moose antler measurements related to age based on 383 specimens harvested in October. Age *(CRC) (Years) Sample Size Average Beam Circumference (in.) Average Maximum Spread (in. ) Average Number of Points more than 1" long /, *CRC = Cementum Ring Count Ie N N 00 Variability in greatest spread of moose antlers based on 383 specimens h~vested in October. Age (year) Minimum L Average MaJdmum Sample Size Variability in number of points (more than one inch long) on moose antlers based on 383 specimens harvested in October. Age (year) Minimum Average Maximum Sample Size U J

7 229 The number of points also varies a great deal. Both the 9.5 year old and the 12.5 year old age samples included antlers with as few as nine and as many as twenty-nine points. A sample of antler measurements were compared from so-called accessible areas (by vehicle) and inaccessible areas (by aircraft). The accessible areas generally have been recently disturbed by logging whereas the inaccessible areas have had no logging. No apparent correlation c~uld the basis of the data examined. be found between these two types of areas on In some cases mean measurements tended to be higher in accessible areas for some age classes and in other age classes they were higher in inaccessible areas. This also tended to be the case for the total number of points related to age. It is felt that the greatest single factor limiting a valid comparison was the small sample size availaole from inaccessible areas.

8 230 antler spread ~... no. of points fr... sample size (n 383) ~ ~ 50 ~.E 1 ~ Ii ~ D E ~ 30.~ ~ j t tt I L J t 1~ 2'.<, 3'.<, ~...,,'.<, 61(, 7'.<, I'.., 91(, 10'.., HI(, 121(, 13~ I~"" age in y.aol + Figure 1. Moose antler variability related to age. WEIGHT AND MEASUREJIlENTS RELATED TO AGE ****** **~( *********~(** *~(***** *~, *** Hunters continually speculate on the live weight of moose which they harvest. Game managers on the other hand face the dilemma of being unable to accurately calculate weight since few Ontario weights have been fully documented. Each year stories of moose in the 1,500 to 1,800 pound range are circulated. Due to the large size of this

9 231 species, it is not an easy task to weigh moose unless special equipment is available. One of the most difficult problems encountered is that of getting both scale and freshly killed moose together. Bearing these factors in mind it was decided to attempt to weigh as many as possible of the whole dressed moose (i.e. with only the blood and viscera removed) being transported past the check station. V~THODS All specimens were weighed and measured during the first two weeks of the fall hunting season, 1966 through Vehicles carrying whole moose generally drove beneath a fixed overhead beam supporting a block and tackle with a scale attached. The scale was lowered and affixed to the animal by means of a heavy rope. The entire carcass was then elevated by hand until it swung clear of all ground support. Two types of weighing scales were employed. In 1966 a large dial scale calibrated in 20 pound intervals and found to read accurate within 10 pounds was used. In all subsequent years a Dillon Dynamometer calibrated in 10 pound intervals and found to read accurate within 5 pounds was employed. In most cases all body measurements were taken on the elevated animal using a steel tape measure calibrated in 1/8 inch intervals. Body measurements recorded included: total length, shoulder height, neck circumference, heart girth, ear length and hind foot length. Estimated live weights were calculated using a 24% loss on field dressing estimated by Nunan (1965). Both wear class age as described by Passmore, Peterson and Cringan (1955) and the incisor cementum ring count age (Sergeant and Pim10tt, 1959) were recorded for each specimen wherever possible.

10 232 RESULTS AND DISCUSSION A total of 81 aged moose were weighed and measured during the six year study. The heaviest animal weighed was a 4.5 year old bull who tipped the scale at 1,050 pounds field dressed weight. A male calf weighing 240 pounds field dressed was the lightest animal documented. The variability in dressed weights are shown in Table 2 and Figure 2. Table 2. Variability in Field Dressed Weight of Black Sturgeon Moose by Sex and Age Male Minimum Average Maximum Sample Size FEmale Minimum Average Maximum Sample Size o Seven male calves averaged 309 pounds while three female calves averaged 345 pounds dressed weight. The heaviest calf, a female, weighed 410 pounds field dressed. Nineteen male yearlings averaged 561 pounds field dressed while seven females averaged 509 pounds. Eight bulls aged 2.5 years old averaged 718 pounds while two females of the same age averaged 689 pounds dres~ed. It appears from the limited data that in each age category except calves, males are some-

11 233 what heavier than females. The greatest weight increase occurs during the first half of an animal's life and continues somewhat reduced up to three years of age after which increased growth tends to level off. The very rapid growth of calves during the first five months of their lives has also been documented by Simard (1970) in Quebec where calves reach a live weight of 300 to 500 pounds by October. Very old animals (13.5+ years) appear to be lighter on the average than those in the prime or middle age category. Additional weights of older animals are needed however to draw more definite conclusions. The heaviest animals weighed were bulls in the 4.5 and 5.5 year old age category. In three cases a complete live or round weight except for blood loss, was followed by field dressing and re-weighing. Weight loss varied from 14.8 to 28.9%. It appears that there may be a good deal of variation concerning percentage weight loss due to field dressing among sexes and ages. It should therefore be stressed that the 24% loss described by Nunan (1965) is an average rule of thumb rather than an accurate method of calculating such weight loss. Of the six body measurements taken along with body weight, most tended to increase as the animal increased in age from calf to 2.5 years. Again as found with weight, it appears from the limited data that in each age category except calves, males are somewhat larger in body form. This dimensional difference shows up well in total length. Ear length and hind foot measurements tend to have reached maximum growth by 2.5 years for both sexes.

12 i r " 400 J! ~ co: 300 o:! t> male meano~(n'7") IwnaIe mean.6. ~/ 100 ~, I~, 21-, 31-, 41-,,I-,,It, 7~ lit,.it, IOIt, lilt, 12~, 13~ 1.1t, age In~. Figure 2. Variability in field dressed. weights of moose related to age and sex. EYE LENS WEIGHT RELATED TO AGE *** **** ****** ******* ** *** The use of the eye lens weight as a criterion of ageing is based on the concept that lens growth does not cease with that of the rest of the body, but is continuous throughout the whole period of the animal's life. Since Lord (1959) described the use of the oven dry weight of the eye lens for ageing cottontail rabbits (Silvilagus floridanus) this technique has been applied to a number of other mammals and birds with varying degrees of success. (1967) examined eye lens weights of moose and found considerable Simkin overlap among age classes. The objective of this study was to gather

13 235 lens weight information to directly compare to that collected by Simkin. METHODS The methods of collection, preservation, age determination and lens weight calculation closely followed those described by Simkin (1967). All calves and yearlings were aged by tooth eruption. The balance of the adults 2.5 years old and older were aged by the incisor cementum ring count technique as described by Sergeant and Pimlott (1959). RESULTS AND DISCUSSION Table 3 illustrates the comparison of the eye lens weights by sex and age using this ageing criterion. A total of 481 moose (328 males and 153 females) were aged, placed into one of sixteen age classifications and mean weights of each classification calculated. The lightest lens weighed came from a male calf being.2739 grams and the heaviest from a thirteen year old male whose lens weighed.9588 grams. Figure 3 further illustrates the actual lens weight distribution related to age. Continuous data, above and below the mean is shown by means of a diamond shaped distribution pattern centered about each mean. Individual lens weights which fall outside this continuous distribution pattern are s~parately plotted. Only 3 of 142 lenses taken from yearling moose fall in the 2.5 year old continuous weight distribution pattern. However 3 lenses of 51 designated 2.5 years old, 3 out of 60 designated 3.5 years old and 1 of 44 designated 4.5 years old, fall in the yearling continuous weight distribution pattern.

14 236 Table 3. Comparison of Moose Eye Lens Weights by Sex and Incisor Cementum Ring Age _ 5 Age nm x gms nf x gms nnmf xgms -! H! H HlO ! ~ ! ! ! ! ! ! lo! ll! ! ! ! 2.8' ! f, I By cementun annuli in first incisor 2 Number of males in sample 3 Number of females in sample 4 Total sample both sexes 5 Mean lens weight in grams

15 237 It appears therefore that the age of yearlings and calves can be determined with a high degree of exactness, solely by the dried eye lens weight. Adult moose exhibit a much slower rate of lens growth as age increases. Hence overlapping of continuous lens weight data is common. There are cases, for example, of a lens from a 6.5 year old moose, whose weight could also fit into the continuous weight distribution pattern of a 5.5, 4.5 and 3.5 year old animal. The data from this study support the findings of Simkin which indicated that lens weight reliably separated calves and yearling moose. Overlapping of lens weight in animals older than yearlings indicated that lens weights appear to have little application as an exact criterion of age.

16 I. : ~ ~. 2 'sampl e size.. ~. - ~ '= C).- ~.6 tn c: Q) ~ 6_meon- Donom eon... V Dalo a Age in Year. Figure 3. Eye lens weight distribution related to age.

17 239 LITERATURE CITED Cringan, A. T Studies of moose antler development in relation to age. Appendix B, North American Moose by R. L. Peterson, University of Toronto Press. Cringan, A. T About moose antlers. Northern Sportsman, November, 4pp. Ellis, R. C The impact of management practice on boreal ecosystems. Projet Program Analysis, Unpublished, Great Lakes Forest Research Centre Canadian Forestry Service, Sault Ste. Marie, Ontario. Lord, R. D., Jr The lens as an indicator of age in cottontail rabbits. J. Wildl. Mgmt. 23(3): Nunan, P. J Moose Weighing Project, Port Arthur District. Unpublished District Report. Rowe, J. S.; Forest Regions of Canada. Canada Department of Northern Affairs and Natural Resources, Forestry Branch, Bulletin 123. Sergeant, D. E., and D. H. Pimlott Age determination in moose from sectioned incisor teeth. J. Wildl. Mgmt. 23(3): Simard, B. R The Moose. National Meat Institute Inc. Montreal, Que. 192pp. Simkin, D. W A comparison of three methods used to age moose. Proc. N. E. Sec. Wildl. Soc., Quebec, P. Q. 13pp. Timmermann, H. R. 1966, A study of the moose harvest, Black Sturgeon area, Port Arthur District. Unpublished District Report. Timmermann, H. R The Antlers of the Moose, development related to age. Ontario Fish and Wildlife Review. 10(1-2): Tolmie, K. J Black Sturgeon moose checking station. Unpublished District Report.