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DOCUMENT CONTROL

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ALASKA RESOURCES LIBRARY

Arctic Gas u.s. DEPT. OF INTERIOR

BIOLOGICAL REPORT SERIES VOLUME FIVE

DISTURBANCE STUDIES OF CARIBOU AND OTHER MAMMALS IN THE

YUKON AND ALASKA, 1972

Ka H. ~cCOURT, J. D,. FEIST, D. DOLL, J. J. RUSSELL

Prepared by

RENE\VABLE RESOURCES CONSULTING SERVICES LTD.

JANUARY, 1974

CP\NADIAN ARCTIC GAS STUDY LIMITED

ALASKAN ARCTIC GAS STUDY COMPANY

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TABLE OF CONTENTS

PAGE

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . A STUDY OF THE REACTION OF CARIBOU AND DALL SHEEP TO THE SIMULATED SOUND OF A COMPRESSOR STATION - ABSTRACT. • • . . . . INTRODUCTION. • • • • • • • • • • 0 • • • • • • •

APPAR-ATUS . . . . . . . . . ~ . . . " . . . . . . . . . Purpose of Equipment . • • • • • • • • • • 0 • • •

METHODS . • . . . . . . . . . . . . . . . . Selection of Study Area. • . • • • • •.....• Assembly of Apparatus. • • . • • . . . . . . . . • .• Data Collection. . . . . . . •.••.•....• a. Design of the Experiment. . . . • • . . . • . . . b. Types of Data Recorded • . • • . . . • . • . Definition of Terms •••• e •• ~ • • ••••••

Sex and Age Categories. . . ......••• Chute Pass and Old Crow Mountain Experiments •.•.. Jago River, Bell River and Schaeffer Mountain Experitnents • • . . • . • . . . • . . • . Individual Behavior . . • • . ~ • . . . . . . . . ..

Feeding Behavior . . . . . . • • • . . • Walking, Trotting, Running . • • . . . . Bedding. • • . • • . • • . . • •. Nur·s ing. • . • . • . . . . . Ear-Eye., . . . . . . . . . . . . Alann Pose . . ~ . . . . . . . . . . . .

PRESENTATION AND ANALYSIS OF RESULTS. . . . . . . . . . . . . . EXPERIMENTS WITH CARIBOU .•• . . . I. SPRING MIGRATION - CHUTE PASS EXPERIMENT . . .

A. B.

c. D.

Introduction. • . . . . . . . . • . Methods . . . . . . . . . . . . • . . . • 1. Selection of Study Area. . . . . . . 2. Assembly of Apparatus. . . . . . 3. Data Collection. . • . . • . . . Description of Study Area . . . . . . Results . . . . . . . . • . . . . . . . • 1. Meteorological Conditions. . . . 2. Group Size and Composition • . . . . 3. Comparison of Caribou Behavior During

and Control Periods. . . . . . . . . a. General Behavior. . • . b. Initial Reactions .

Overall Responses • . . . .

c. • • • If • •

. . . . . . .

. . . . . . . . . . . . . . • . . . . . . . . . . • . . . . . . . • . . . . . . . • . • . Test . . • . . .

. • . • . . . : . . .

' ' . • • . '\ . ' . - • I ~ • o

i

1

3

6 6

8 8 9 9 9

10 11 11 12

12 12 12 12 12 12 13 13

14

15

15 15 15 15 16 18 18 19 19 21

21 21 23 24

' . .. . .. .. . • ~ 0 • • •

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E. Summary . . . . . . . . . . . . . II. SPRING MIGRATION - OLD CROW EXPERlMENT •.....

4. Introduction .•..............••... · . B. Methods . . . • . .. . . . .. . . • . n • • • • .... ; • ..

1. Selection of Study Area. . ...•.•. 2. Assembly of Apparatus. . . . . . . . .. 3. Data Collection. . • . . . . . ...

C. Description of Study Area. . . ..•.• D. Sound Levels . • • . . • . . . . • . . . . . . • . E . Re su 1 t s . . . • . . . . . . . . • • . . . . . . . . .

1. Meteorological Conditions ....... . 2. Group Size and Composition • . . . . . . . . 3. Group Responses ......•........

a. Initial Reactions . . . . . . . . . .. b. Overall Responses . . • . • . . . .

4. Behavior of Individuals. . • . .. . • . . . • a. Nature of the Sample. . . . • . . . . . b. Comparison of Caribou Activity During

Test and Control Periods •......... F. Sununary . • • • • c: • • • • • ~ • • • .. •

III. CALVING GROUNDS - JAGO RIVER EXPERIMENT .• A. Introduction. . . . . • . q •

• • • 0

• 4

B.

c. D. E.

F.

Methods . • . • • • . . . . . 1. Selection of Study Area .. . . . . . . 2. Assembly of Apparatus. 3. Data Collection ..... . . . . . . . . Description of Study Ar~a . . . • • • .. . . . . . . . Sound Levels. . . . . . . . e • • • • • • • • • • • •

Results . . . . . . . . . . . . . . t. •• o •

1. Meteorological Conditions. . . . . . . . • . . . 2. Group Size and Composition . • • . . . • . . . . 3. Gener~l Behavior ..•.••••••••••.. 4. Behavior of Individuals. ~ . . . • . . .•.

a. Nature of the Sample •••••••••••. b. Comparison of Proximity of Caribou to

the Sound Simulator during Test and Control Periods • • . . • . • • • • • . . .

c. Comparison of C~ribou Activity during Test and Control Periods. . . ...

Summary . . . . . . . . . . . . . . . . . . . .

PAGE

24

32 32 32 32 32 33 33 36 36 36 39 42 42 42 47 47

50 59

62 62 62 62 62 63 63 65 65 65 65 68 71 71

74.

74 87

• ~ • • ... .. • • . • • 0 • .

• u ":: , • 0 ' • ,

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\. ... IV . SUMMER MOVEMENTS - BELL RIVER EXPERIMENT . . . . . . .

PAGE

89 89 89

A. Introduction. . • . • . . . . . . . ...•. B. Me thad s . . . . • • • . . . . . • • . . . . • . .

c. D.

E.

1. Selection of Study Area and Assembly of Apparatus. . • . . . . . . . . . . . . .

2. Data Collection. . . . • . . • . • . . . Description of Study Area • . • • . . . . • • Res.ul ts . . . . . . . . . . . . . . . . . . . " . 1. Meteorological Conditions .• ~ •...... 2. Group Size and Composition . • • • • . . • • . . 3.. Comparison of Caribou Behavior During Test

and Control Periods •....•.•.....•. Sununary . . . . . . . . . . . . . . . . .

89 90 92 92 92 92

93 97

FALL MIGRATION - SCHAEFFER MOUNTAIN EXPERIMENT • . . . . . 98 A. Introduction. . . . . . . . . . . . • . • . . . • 98 B. Methods . . . . . . . . . . . . . . . . . . . . . 98

c. D. E.

F.

1. Selection of Study Area. • • . . . • • . • . 98 2. Assembly of Apparatus. . • . 9 • • • • • • • 99 3. Data Collection .•.... ~ n • • • • • • • • • 99 Description of Study Area . . • • • . . . . . . . 99 Sound Levels ........•.••......••. 100 Results . . ,. . . . . . . (t • • • • • • • • • • • • • 100 1. Meteornlogic~l Conditions. . • • . • . . • . . . 100 2. Group Sizt; and Composition • • • . • . • 100 3. Comparison of Caribou Behavior During Test

and Control Periods ..•.•. s •••••••• 103 Summary . . . . .: . . '~ . . . . . . . . . . . 107

DISCUSSION .... . . . . . . . 109 ~ ... B.

c.

Seasonal Activity • . . • • . • • Environmental Variants ....

. . . . 109 . . . . . . . . . . 109 . . . . . . . . 109 . . . . . . . . . . 110

1. Climate .•.•.. 2. Terrain and Vegetation . 3. Parasites and Predators. Social Variants . . • . 1. Group Size .••.•.. 2. Group Composition .•..

0 • • • • • • • • • 111 . . . . . . . . . . . 112

. . . . . . . . 112 . . . . . . . . . . 113

CONCLUSIONS AND RECOMMENDATIONS . . 118

DALL SHEEP EXPERIMENT • . . . . . . • • • . . . . . 119 A. Introduction. • • • . . . . . • . • . 119 B. Methods • . . . . . • . . . . .•....•. 119

le Selection of Study Area. . ......•.. 119 2. Assembly of Apparatus. • . . • • . . ..•••. 120 3. Data Collection. . . . • • • . . . . • . • . 120

C. Description of Study Area . . . ...•.•... 121 D. Results and Discussion. . . • • • • . . • • . • • . • 123

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PAGE

1. Activity Patterns. . . . . . . . . . ...• 123 2~ Additional Behavior Observations . • • . • • . . 127 3o Dispersion ... 0 •• o • o ••••••• " o • 128 4. Relationships between Activity and Dispersion •. 131

E • S UII1II1a ry . . . • . . • . . . • . . . . 13 3 F. Conclusions and Recommendations . • • ••.... 134

A STUDY OF THE RESPONSE OF CARIBOU TO CUTLINES ENCOUNTERED DURING WINTER AND SPRING MIGRATION - ABSTRACT . • • . . • . 135

INTRODUCTION. . . . . . . . . . . . . . . . . . 136

OBJECTIVES . . • • • • • • • • • ao • • " • • • • • . 137

MARCH STUDIES . . . . . . . . . . . . . . . 138

I.

II.

METHODS. • s • • • • • • • • • • . . . • 0 • • . . 138

Results . ......... ~ ....... . . . . . . 139 . 140 . 140

A. Non-nival Characteristics . • • 0 •

B.

1. Use by Vehicles. . . . . . .• • 0 • • • •

2. Density of Forest in Area Adjacent to

3. 4.

Corridor . • . . • • • . . . . • • • 140 Orientation of Line .••• Corridor Wi-dth • . • • • •

. . . .

. . . . . • . • . . . 141

. . . . . 141 Nival Characteristics • • • • • • • • • 0 • • 141 1. Snow Crust • • • • . • . • • • • . . . . . • 141

a. Depth of Crusts . • . • ., • • • b. Number and Hardness of Crusts • o •

2. Snow Depth and Track Depth • 0 • • •

. . 141 . . • • 142 • $ • • 144

III. S~1ARY OF RESULTS • . . . . . • • . . . . . . . . . . 151

IV. DISCUSSION • ~ • 0 • • • . . . . . . . . . . . . . 152

MAY STUDIES . . . . • . • • • . • • . • . . . • 156

I. METHODS. . . . . . • • • . • . . . . . . e . . . • 156

II. RESULTS. . . . . . . . . • . . • • • • . . . . • • 158 A. Snow Conditions . • . . . . . • . . . . . . . • " 159 B. Forest Cover. • • . • . • . . . • • . • • . • • • • . 159 C. Terrain . . . . . . . . . . . . . . . . . . . 162 D. Use of Vehicles . . . . • • • • . . . . . 162 E. Orientation . . • . • • • . . • • • • • . . . • . 164

III. SUMMARY OF RESULTS . . . . . . . . . . . . . . 168

IV. DISCUSSION . • • • • . . . . . . . . . . 169

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___ ,,.._.,,... ... -.--~

• ~ • ' I • ; "" • • . • . •

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v. CONCLUSIONS AND RECOMMENDATIONS. . . . . . . . . . . Ar Winter Range ........ . . . . . . . . . . . . B. Spring Migration ..... . . . . . . . . . . .

EXPERIMENTS ON DEFLECTION OF CARIBOU FROM CUTLINES. 8 ••••

A. Introduction. . . • . . . . . . . • . • . • • • • 8

B. Methods . o • • • • • • • • • • • • • e ••••

c. D. E.

Results ..•. . . . . . . . . . . . . . . Discussion .•••••••• . . . . Conclusions • . • . . . . . . . . . . .

A STUDY OF THE REAGTIONS OF CARIBOU, MOOSE AND GRIZZLY BEAR

PAGE

. 173

. 173 - 175

• 177 . 177 • 177 • 177 . 179 . 180

TO AIRCRAFT DISTURBANCE - ABSTRACT? • . • . • • . • . • . • 181

I. REACTIONS OF CARIBOU TO AIRCRAFT DISTURBANCE . . . . . A. B. c.

D.

Introduction. . • . . • . . . . . . . . . . . . Methods . . . . . . . . . . . . • . . " . . . 0 • . Results . . • . . . • • . . . . . . . . . • • . . . 1. Reactivity of Caribou to Different Types

of Aircraft. . . . . . . . . . . . . . . . . . 2. Reactivity of Caribou to Aircraft Flying

at Different Altitudes . . . . . . . . . . . . 3. Reactivity of Groups of Caribou Engaged

in Different Activities. . . . . . . • . . 4. Reacti,Jity of Caribou in Relation to Group

Size .. . . . . . . . . . . . . . . . . . 5. Reactivity of Caribou in Relation to

6. Seasonal Activity. . • . • . • • • . . • • . . Reactivity of Caribou in Relation to Habitat Type • • • . • • • • . . . . . • .

Summary of Results. . <> • • • • • • • • • • • • • •

E. Discussion .••••• ~ • • • • . . • . .

183 . 183 . 184 . 185

. 185

• 187

. 188

• 193

. 193

. 198

. 201 • 202

I~. REACTIONS OF MOOSE AND BARREN GROUND GRIZZLY BEAR TO AIRCRAFT DISTURB~~CE • . . . . . • . • • • • • . . 209 A. Introduction and Methods ••••.••......•• 209 B. Results . . . . . . . . . . . • . . . . . . . ... " 209

1. Moose. . . . . . . . . . . . . . . . . . . . . . 209 2. Barren Ground Grizzly. . . . • • • . • • • • . . 211

C. Discussion .•• ~ •••••••.•••.••••.. 213

RECOMMENDATIONS . . • . . • e. • • • • • • . . . . . . . 215

REACTIONS OF CARIBOU TO MAN-MADE OBJECTS. . . . , . . . • 216

PARKIN BASE CAMP. • • • • • • • • • • • • • • • 4 • 2.16

orL STORAGE TANKS . . . . . . . . . . . . $ • • • • • • • ~ 216

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vTHITE SNOW MOUNTAIN SEISEMIC CAMP · • • • • . . . • 0 0 • •

PAGE

216

OLD CROW TOWNSITE . . . . . . . . . . . . . . . 217

GROUNDED AIRCRAFT • • • . . . . . 0 • . . ~ . . . . . .. . . . • 217

218 LITERATURE CITED. • • • • • 0 . . . . . . . . . .

Table 1.

Table 2.

Table 3.

Table 4o

Table 5o

Table 6.

Table 7.

Table 8.

TABLES

A comparison of meteorological conditions observed during periods of caribou movement through the Chute Pass under experimental and control conditions, and periods of no caribou movement .•••• o • • • • • • • •

. . . 20

Comparison of group size and composition of caribo~ observed during the Chute Pass experiment 22

Comparison of the distances caribou groups passed from the sound simulator during the Chute Pass experiment .•.••••••• . . . . . . . . Sound pressure level readings at the Old Crow experfmental site • • • • . • o • • • • • • •

• •

• •

Summary of meteorological conditions at the Old Crow experimental site, 1972. . • • o • . . .

29

37

38

Con~arison of sex and age composition of groups of caribou observed each day for control and test periods of the Old Crow experiment. • • . • . . • 40

The closest distance caribou groups were observed from the sound simulator during the Old Crow experiment • • • • • • • • • . • • . . • • . • • • 46

Sex and age composition of caribou for which behavioral observations were recorded during the Old Crow experiment .•••••.•••• . . 48

. . , r . • .. · • • • • - • . • . . - . . . . .

..

• •

•

•

Table 9.

Table 10.

Table 11.

Table 12.

Table 13.

Table 14.

Table 15.

Table 16.

Table 17.

Table 18.

Comparison of the temporal distribution of caribou for which behavioral observatio~ls were made during control and test periods of the Old Crow experiment ....... .

Comparison of numbers of caribou for which observations were made at various distances from the sound simulator during control and test periods of the Old Crow exp~riment

Comparison of mean number of changes in activity per animal during a five minute period for different age-sex classes during test and control periods of the Old Crow experiment. • • . . • • • . . . • • . .

Comparison of mean number of changes in act­ivity per animal during a five minute period at various distances from the sound simulator during test and control periods of the Old Crow

PAGE

49

51

58

experiment. • • • • • . . . . . • . . . . . . 60

Sound meter level readings of the sound simula-tor on June 20 at the Jago River experiment . • . 66

Comparison of weather conditions during exper­imental and control periods at the Jago River experimental site . . . . • • . . . . . . . . • . 67

Comparison of age~sex composition of caribou for which behavioral observations were recorded dur­ing control and test periods of the Jago River experiment. • • • • • . . . • . . . . . . • . 72

Comparison of the temporal distribution of caribou for whiGb R§havioral Qbservations were made during control and test periods of the Jago River experiment. . . ~ • ! ~ ! • ! • • • • , ! • • • • 7 3

Comparison of numbers of caribou for which be­havioral observations were made at various dis-tances from thg sound simulator during control and test periods of the Jago River experiment . . 75

Comparison of mean number of changes in activity per animal during a five minute period for dif­ferent age-sex classes test and control periods of the Jago River experiment. . . • . • • . • . • 84

•

•

Table 19.

Table 20.

Table 21.

Table 22.

Table 23.

Table 24.

Table 25.

Table 26.

Table 27.

Table 28.

Table 29.

Table 30.

..

Comparison of mean number of changes in act­ivity per animal during a five minute period at various distances from the sound simulator during test and control periods of the Jago

PAGE

River experiment . . . . . . . • . . . . . . 86

Sound pressure level readings at the Schaeffer Mountain experimental site . • . . . . .. • . . . 102

Sex and age composition of caribou classified during the Schaeffer Mountain experiment. • • 104

The closest distance caribou groups were observ­ed from the sound simulator during the Schaeffer Mountain experiment . • . . . . . . . . . Comparison of the average number of sheep using high, talus, and low zones of the ridge during

• 106

four phases of the experiment • • • • • • . . . • 129

Numbers of observations of animals engaged in various activities at different elevations and experimental conditions . . . • • • • . • • . • . 132

A comparison of the numbers of snow crusts in the forest adjacent to corridors showing concen­trated use by caribou and those showing no con-. centrated use, March, 1972. • • • • • • • . . 143

A comparison of the numbers of snow crusts on and adjacent to cutlines, where snow had not been disturbed by vehicles, March, 1972 .••••... 145

A comparison of snow depths in the forest adja-cent to cutlines ~.vhere ~oncentrated and no con­centrated use was observed, March, 1972 .•..• 147

A comparison of track sinking depths in forest adjacent to cutlines where concentrated and no concentrated use was observed, M~rch, 1972. • • . 147

A comparison of snow depths on c.utlines where concentrated caribou use was observed to snow depths on cutlines where no concentrated use was observed, March, 1972 • • • • • . • • • . 148

A comparison of track sinking depths on cutlines where concentrated caribou use was observed to track sinking depths where no concentrated use was observed, March, 1972 ••••. ~ ,. a •••• 148

• ..

•

Table 31.

Table ~2.

Table 33.

Table 34.

Table 35.

Table 36.

Table 37.

Table 38.

Table 39.

Table 40.

Table 41.

PAGE

A comparison of the difference in snow depths, on and adjacent to cutlines where concentrated use was observed to differences where no concen­trated use was observed, March, 1972. . . . . .. 150

.t\ cor·.~-,~ f. ison of the difference in track sinking dleprd·~:: :m and adjacent to cutlines where concen­tratt.·' .;.ise vJas observed to differences where no conce:...:::rat .: use was obr:;erved, March, 1972 .... 150

A comparil;on of the percentage snow cover on corridors foll::>.'wetl :I: .. th that on corridors crossed by caribou w·han encountered during spring migra-tion; May, 1972 ... ! ••••••••••• 160

A comparison of tl:e forest co .. .ter adjacent to cor­ridors followed by carj_bov.:.:,. 9{l.th those crossed when encountered on dpring migration; May, 1972 . 161

A comparison of the terrain type 1'£1 the vicinity of corridors followed to those c1:-osse{l when en­countered by caribou on spring migration; Nay, 1972. e e • •. • • e ••• I. •. e. D •• 163

A comparison of the numbers of corridors followed as opposed to crossed where the corridor had or had not been travelled by a vehicle; May, 1972 .. 165

A co~parison of the numbers of corridors crossed to ~allowed in a range of angles cf deflection or podsible deflection • • • . • • • • • . • ~ . 165

The degree of reaction of caribou to Cessna 185 and Bell 206 aircraft for four ranges of altitude of aircraft. March - October, 1972 • ! ••••• 186

Comparison of the reaction of caribou engaged in four different activities to fixed-wing aircraft at three different altitude ranges. : .•••.• 191

Reactions of various sizes of groups of caribou to fixed-wing aircraft at different altitudes • . 194

Comparison of the reactions of caribou to fixed­wing aircraft during winter range, spring migra-tion, and sununer movements .••••..•..•. 196

•

•

... •

Table 42.

Table 43.

Table 44.

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Figure 8.

Figure 9.

PAGE

Comparison of the reactivity of caribou in two different habitat types to fixed-wing aircraft .. 199

Reactions of moose to disturbances from Cessna 185 aircraft in a range of altitudes, March - October, 1972. . . . . . . . . . . . . 0 • • • • • •••• 210

Reactions of barren ground grizzly to disturbance from Cessna 185 aircraft in a range of altitudes, March - October, 1972 ••.••••••..••• 212

TABLE OF FIGURES

Diagram of the Chute Pass experimental site • • • 17'

Routes travalled by caribou groups during test conditions of the Chute Pas.s experiment • • • • • 25

Routes travelled by caribou groups during con-trol conditions of the Chute Pass experiment. • • 26

Comparison of the time of day at which caribou crossed the Chute Pass under test and control conditions. . . . . . . . . . . . . . . . . . Location of Old Crow experimental study area and caribou movements during spring migration

Physiography and vegetation of the Old Crow experimental study area • • • • • • • • • •

Daily age-sex composition of caribou during the

28

34

35

Old Crow experiment • • • • • . • • . . . . • 41

Relative number of caribou, as shown by arrow widths, and routes used to traverse the Old Crow experimental study area during test conditions. • • • • • • . • • • • • . • • 43

Relative number of caribou, as shown by arrow widths, and routes used to traverse the Old Crow experimental study area during control conditions 44

. . "" • • ' ' '!,..) • • \> I • ., ~ ' n '

• ..

•

•

Table 42.

Table 43.

Table 44.

Figure 1.

Figure 2.

Figure 3.

Fig,~lre 4.

Figure 5.

Figure 6.

Figure 7.

Figure 8.

Figure 9.

PAGE Comparison of the reactivity of caribou in two different habitat types to fixed-wing aircraft .. 199

Reactions of moose to disturbances from Cessna 185 aircraft in a range of altitudes, March - October, 1972~ . . . . . 0 • • • • • • • • • • • • • • • • 210

Reactions of barren ground grizzly to disturbance from Cessna 185 aircraft in a range of altitudes, March - October, 1972 ••.•••••...••• 21~

TABLE OF FIGURES

Diagram of the Chute Pass experimental site • • • 17

Routes travelled by caribou groups during test conditim.1s of the Chute Pas.s experiment • • • . • 25

Routes travelled by caribou groups during con-trol conditions of the Chute Pass experiment. . • 26

Compa:risc" of the time of day at which caribou crossed the Chute Pass under test and control conditions. . . . . . . . . . . . . . . . . . . . Location of Old Crow experimental study area and caribou movemants during spring migration

Physiography and vegetation of the Old Crow experimental study area • • • • • • • • • • . . .

28

34

35

Daily age-sex composition of caribou during the Old Crow experiment a • • • • • • • • • • • • 41

Relative number of caribou, as shown by arrow widths, and routes used to traverse the Old Crow experimental study area during test conditions. • • • • • • • • • • • • • • • • . 43

Relative number of caribou, as shown by arrow widths, and routes used to traverse the Old Crow experimental study area during control conditions 44

•

•

' "'' ...... ~~·~ ).,..,~~....;....,_~---~..-,.,._,. ---~- .,.;; ____ ~--~ . .-.....:. .. -;;"_;.__ -~- ··-·--·-·-- '

Figure 10.

Figure 11.

Figure 12.

Figure 13.

Figure 14.

Figure 15.

Figure 16.

Figure 17.

Figure 18.

Figure 19o

Figure 20.

Figure 21.

Figure 22.

Figure 23.

Comparison of caribou activity during test and control periods at various distances from sound simulator during Old Crow experiment .. . . Comparison of daily a'" tivity patterns e:1:hibited by caribou during test and control periods of the Old Crmv experiment . . • • • • . • • . .

Location of the Jago River e~periment on the caribou calving grounds in Alaska • . • • • • . . Percentage of cows without antlers on the calv­ing grounds in June during the Jago River

PAGE

52

54

64

experiment. . . . . . • • • • • • • • • • • • . • 70

Caribou activity at various distances from sound simulator during Jago River experiment. • • • • • 77

Comparison of daily activity patterns exhibited by caribou during Jago River experiment • • • 81

Caribou herd size, location and movements on July 24, in relation to the Bell River experi-mental study area • • • • • • • . . . o . . . . • 91

Movements of caribou through the Bell River experimental site on July 24, 1972 .••.• . . . Progression of movement of the caribou herd past the sound simulator during the test period

94

of the Bell River experiment •..•..•.•• ~ 96

Location, physiography and vegetation of the Schaeffer Mountain experimental study area ••

Caribou movements during test and control con­ditions of the Schaeffer Mountain experiment.

• •

• •

101

105

Patterns of habitat utilization by Dall sheep at the experimental site in the Richardson Mountains 122

Dall sheep activity patterns during cont~ol con-ditions of the Dall sheep experiment. . . . • 124

Dall sheep activity patterns during test condi­tions and helicopter disturbance of the Dall sheep experiment. • • . • . . . • . • • • • • ~ . 126

• •

(J , '" • , • • • I ~ ~ ' , • • • • • . .... . .. . . . . . ' ,. . . , •

Figure 24.

Figure 25.

Figure 26.

Figure 27.

Figure 28.

Figure 29.

Appendix A.

Appendix B.

Appendix C.

Appendix D.

Appendix E.

Appendix F.

PAGE

The realtionship of orientation of a corridor to the distance of deflection by caribou. . •.• 167

Paths of three groups of caribou which encoun-tered a snow~ence barrier on a cutline. • • • • . 178

Reactions of caribou groups to disturbance from Cessna 185 and Bell 206 aircraft • . • • • • 189

Reaction of caribou groups engaged in various activities to aircraft disturbance •••••••. 192

Reactions of various sizes of groups of caribou to aircraft disturbance . . . . . • • • • • . • • 195

A comparison of the reactivity of caribou in dif­ferent habitat types to aircraft disturbance. • • 200

APPENDICES

Photographs illustrating some aspects of dis­turbance studies carried out during 1972

A description of the Mann-Whitney U Test compar­isons of data collection on behavior of indivi­dual caribou during test and control periods of the Old Crow and Jago River experiments • . • • • 223

Data pertaining to nival conditions on corridors which were used extensively by caribou; March, 1972. • • • • • • • • • • • e • • • e • • • e • • 231

Data pertaining to nival conditions on cutllnes not used extensively ~y caribou. March, 1972 •• 232

Data pertaining to conditions on corridors on which caribou travelled during the 1972 spring migration. May, 1972 ••••••••• .. . . . . . 236

Data pertaining to corridors which were immedi­ately crossed during spring migration. May, 19 7 2 e • a .c • e • • e • e e • • • • • e eo • • • e 2 3 9

•

..

•

- i -

PREFACE

Studies of the environmental impact of a proposed gas pipe­

line on large mammals involve three major phases of research: base­

line studies, problem solving studies, and monitoring studies.

Results of baseline studies, including research on the distribution

and abundance of mammal populations and their relationships with

their environment, have been documented in "A Study of the Porcupine

Caribou Herd, 1971", "Distribution and Movements of the Porcupine

Caribou Herd in the Yukon, 1972", "Distribution and Movements of the

Porcupine Caribou Herd in Northeastern Alaska, 1972", and "Distribu­

tion of Moose, Muskox, and Sheep in Northeastern Alaska, 1972"4

The following report incl·.·des the results of studies per ...

taining to the second phase of research. The rationale for these

studies is that in order to minimize the possibility of adverse

effects on the animal population, it is desirable to experimentally

test behavioral responses of animals to simulated environmental

modification. This enables subsequent alterations in engineering

design if necessary. The investigations reported on in this volume

include observations on responses of animals to compressor station

noise, artificial corridors, aircraft disturbance, and miscellaneous

man-made objects.

•

.. •

- 181 -

A STUDY OF THE REACTIONS OF CARIBOU, MOOSE

AND GRIZZLY BEAR TO AIRCRAFT DISTURBANCE

ABSTRACT

While carrying out survey flights data were collected on the

reactions of caribou, moose and grizzly bear to aircraft.

Caribou reacted more strongly to a Bell 206 helicopter than a

Cessna 185 at low altitudes (·-300ft.). No difference in reactivity

to different aircraft occurred for altitudes greater than 300 ft. The

reactivity of caribou to aircraft disturbance decreases as the altitude

of the aircraft increases, up to an altitude of approximately 1000 ft.

Reactions to aircraft at altitudes greater than 1000 ft. are unpredict­

able but infrequent. Groups of caribou which were feeding or bedded

reacted most often to aircraft disturbance, the bedded animals exhibiting

the strongest reaction. A correlation between group size and reactivity

to aircraft was found only at altitudes less than 300 ft. Larger groups

reacted most often and most intensely. Although data were incomplete

for some seasons of the year, no outstanding changes in reactivity were

observed between seasons. Comparison of data collected in two different

habitat types (the Richardson Mountains, and Old Crow wintering areas and

spring migration routes) suggested that the reactivity of caribou was

basically similar between the two. However, the decrease in the proportion

of strong responses with increased altitude that is obvious in the data

for the latter habitat type did not occur in the mountains between the

<300 ft. and 301 - 600 ft. altitude ranges. This may have resulted from

a possible inconsistent relationship between altitude and strength of

stimulus in the mountains because of acoustic factors.

Moose reacted more often than not to aircraft at altitudes less

thau 200 ft. Fixed-wing aircraft at altitudes above 600 ft. elicited no

..

•

•

... _,.

- 181 -

A STUDY OF THE REACTIONS OF CARIBOU, MOOSE

AND GRIZZLY BEAR TO AIRCRAFT DISTURBANCE

ABSTRACT

While carrying out survey flights data were collected on the

reactions of caribou, moose and grizzly bear to aircraft.

Caribou reaeted more strongly to a Bell 206 helicopter than a

Cessna 185 at low altitudes (·-300ft.). No difference in reactivity

to different aircraft occurred for altitudes greater than 300 ft. The

reactivity of caribou to aircraft disturbance decreases as the altitude

of the aircraft increases, up to an altitude of approximately 1000 ft.

Reactions to airc+.aft at altitudes greater than 1000 ft. are unpredict­

able but infrequent. Groups of caribou which were feeding or bedded

reacted most often to aircraft disturbance, the bedded animals exhibiting

the strongest reaction. A correlation between group size and reactivity

to aircraft was found only at altitudes less than 300 ft. Larger groups

reacted most often and most intensely. Although data were incomplete

for some seasons of the year, no outstanding changes in reactivity were

observed between seasons.. Comparison of data collected in two different

habitat types (the Richardson Mountains, and Old Crow wintering areas and

spring migration routes) suggested that the reactivity of caribou was

basically similar between the two. However, the decrease in the proportion

of strong responses with increased altitude that is obvious in the data

for the latter habitat type did not occur in the mountains between the

<300 ft. and 301 - 600 ft. altitude ranges. This may have resulted from

a possible inconsistent relationship between altitude and strength of

stimulus in the mountains because of acoustic factors.

Moose reacted more often than not to aircraft at altitudes less

than 200 ft. Fixed-wing aircraft at altitudes above 600 ft. elicited no

• •

..

•

- 182 -

reaction by moose. Data on reactions of grizzly bear to Cessna 185

aircraft. sho-t·7 ·no consistent trend of decreased sensitivity with

increased altitude. The grizzly bear is more sensitive to aircraft

disturbance than caribou or moose ..

The recommended minimum flight altitude for aircraft in areas

inhabited by caribou, m!Jose, and grizzly is 1000 ft. above ground

,.

I

" "'

•

..

- 183 -

I. REACTIONS OF CARIBOU TO AIRCRAFT DISTURBANCE

A. Introduction:

Exploration and development of northern resources has already

resulted in a great increase in the exposure of the Porcupine Herd to

aircraft. Feasibility studies of a gas pipeline (especially the envir­

onmental sector) have escalated this exposure. Future expansion of air

traffic to include large cargo aircraft, personnel carriers (helicopters

and fixed-wing), and aircraft used in inspection and maintenance of the

pipeline necessitates a knowledge of the tolerance of caribou and other

marmnals to disturbance by aircraft.

Incidental to the collection of data on the distribution and

movements of caribou in 1972 were observations concerning the reactions

of the caribou to the survey aircraft., The majority of the data was

derived from observations from Cessna 185 aircraft; however, a consider­

able number of observations of reactions to Bell 206 jet helicopters

were also made.

The objectives of this study were to gather quantitative

information on:

( 1)

(2)

The response of caribou to different types of aircraft

at different altitudes.

The response of caribou to aircraft disturbance at

difference phases of their annual cycle of activity to

determine whether reactivity to aircraft is dependent

(a) general activity (e.g. migrations, calving),

(b) specific Rctivity (feeding, bedding),

(c) group size and social structure, or

on:

{d) habitat type (forest density or terrain features).

• ..

..

- 184 -

The ultimate objective is the determination of acceptable

levels for ~isturbance of large mammals under the above conditions, to

serve in the development of guidelines for aircraft flying over areas

with known large mammal populations. Delineation of areas of particular

sensitivity is important as well.

B. "t-'!ethods:

Data on the reaction of caribou to survey aircraft were

collected from March to October 1972. Information collected specifically

for this program included the distance of the aircraft from animals and

the degree of reaction of the animals.

Since the aircraft was, in most cases, nearly directly above

the animals observed, distance of the aircraft from the animals usually

corresponded to its altitude above them. For this reason, distances

have been expressed as altitude of the aircraft above the animals.

This distance was estimated to the nearest 100 ft. As the accuracy

of the individual observation was limited, four ranges of altitude were

used in analysis: less than 300ft., 301 - 600 ft., 601 - 1,000 ft.,

and greater than 1,000 ft.

. The degree of reaction to the aircraft was classified in

three categories:

(1) Nil (or no reaction). No interruption of the activity

of the individual animal or group of animals resulted

due to the presence of the aircraft (i.e. feeding animals

remained feeding, bedded animals bedded, etc.). Mere

recognition of the presence of the aircraft by motion

of the head was included in this category. "

(2) Mild reaction. A short interruption in the.activity of

the individual or group occurred as a result of the

•

•

- 185 -

presence of the aircraft. This would include the rousing

o.f bedded animals or a significant interruption in feeding

behavior. The greatest degree of reaction in terms of a

flight response would be trotting.

(3) Strong. The interruption of caribou activity to the extent of

a rapid full scale flight response would be included in this

category. This involved the running flight of a group.

Comparisons of response under different conditions of the aircraft

type ond altitude, physical habitat, location ~nd caribou activities are

made graphically and statistically.

C. Results:

1. Reactivity of Caribou to Different Types of Aircraft:

There is a considerable difference in the intensity (sound

pressure levels), frequency and rhythmic quality of sound produced

between a Cessna 185 airplane and a Bell 206 helicopter. The airplane

noise consists of a more constant droning, while the helicopter pro-

duces a number of distinct sounds, including the '1whine" of the turbine

engine, "roar" of exhaust, and the "slapping" noise produced by the

blades. A total of 1012 observations of caribou reactions to aircraft

were recorded. Of these, 859 were made from the Cessna 185, the remainder

from the helicopter. A comparison of the p~oportions of responses in the

"nil", "mild" and "strong" reaction categories bet\.;reen airplane and heli ~

copter observations, were made to determine whether the nature of the

response was dependent upon the type of aircraft. Tne data and sample

sizes are present in Table 38. A chi-square test was used to test for

independence of the degree of reaction from aircraft type at four ranges

of aircraft elevation. In the 301 -600ft., 601 - 1000 ft., and

greater than 1000 ft., altitude categories, the distribption of nil,

mild and strong responses was independent of the aircraft type.

.. •

•

..

•

. ..

~~-

Table 38:: The degree of reaction of caribou to Cessna 185 and Bell 206 aircraft for four r'anges of altitude of aircraft. March ~ October., 1972 e

AIRCRAFT TYPE <300' 301'-600 1 601'-1000' >1000'

NIL MILD STRONG NIL MILD STRONG NIL MILD STRONG NIL MILD STRONG -- --·---~ - -

Cessna 185 n 46 131 92 110 84 31 216 34 2 93 19 1

% 17.1 48.7 34.3 48.9 37e3 13.8 85.7 13.5 .8 82 16.8 .9

Bell 206 n 0 1 16 46 23 9 41 4 0 14 0 0

% 0 5 .. 9 94.1 59 2.9.5 11.5 91 9.0 0 100 0 0

._. 00 ()'\

_""""',.~_.,. ,....__ l-4--- ....- ......... ---....----- ~ ,- ~ ~t ·~ ,-s~ ~ "J;::'It ·~w

-~, ·-~:-·_,.--~- ~"'~"->'!:'*~~~,-. ~---,-·

•

.. •

- 187 -

At altitudes below 300 ft. a definite diffe · h renee 1n t e reaction of caribou w~s observed, in that virtually all caribou exposed to a heli~

copter reacted strongly, while only 34% of those exposed to the airplane

reacted strongly.

Several possible explanations for this difference in reactions

could be proposed. The nature of the flight of helicopters at this

altitude may have been responsible for the difference, in that more

erratic motion, or a longer period of time spent above the animals

could have caused more alarm than the more constant motion and speed of

the airplane. The differences in noise levels produced by the helicopter

as contrasted to airplane would be greatest at low elevations, as the

equalizing effect of sound dispersion would be least here, and hence

animals would react differently because noise le·vels are perceptually

different. Responses of caribou to the two aircraft at altitudes

greater than 300 ft. were not significantly different.

2. Reactivity of Caribou to Aircraft Flying at Differ~nt Altitudes:

Since both the in.tensity of noise and visual perceptability of

the aircraft increase DS the altitude of the aircraft decreases, a re­

lationship between the altitude of the aircraft and the intensity of

the response it evokes in the caribou was hypothesized. Data relating

the intensity of reaction to the altitude of the aircraft are found

in Table 38.

The percentage of animals showing no reaction it1creased as

the altitude of the aircraft increased, or conversely the number of

caribou showing a reaction to the aircraft decreased as the altitude

increased, The degree of response that was elicited varied with the

altitude of the aircraft. The strength of the response was found to

-~ . . '. •• . • ' • . • : . ·. • . . ·o ·~ _, . ' . . . . •. . . •. • , ."' • ... :" 6 , • •. • .

.. •

..

\ -~

- 188 -

diminish as the altitude of the aircraft increased. The highest proportion

of "strong" resp9nses occurred in the "below 300 ft." altitude range and

comprised 34.3% and 94.1% of all responses to Cessna 185 and Bell 206

helicopter respectively. "Strong" responses comprised 13.8% and 11.5%

of all responses to Cessna 185 and Bell 206, respectively in the 300 -

600 ft. altitude range and less than 1% of the sample in altitudes

exceeding 600 ft. The "mild" response formed the greatest proportion

(48. 7%) of sample in the ''below 300 ft." altitude range for the Cessna 185.

A decrease in the percentage of animals showing mild responses followed

an increase in the 3ltitude.

Mild responses were most commonly observed in the 300 - 600 ft.

altitude range for the helicopter, comprising 29.5% of the sample.

Observations of mild responses declined from this point to 9% in the

601 - 1000 ft. altitude range and no observations of mild reactions were

made at altitudes greater than 1000 ft.

Figure 26 is an illustration of the responses of caribou to

aircraft at difterent altitudes.

The data from the Cessna 185 suggest that increase in elevation

from one level to the next, (e.g. from less than 300 ft. to 300 - 600 ft.)

is characterized by the diminishing of strong responses to mild responses.

The percentage of mild reactions in the higher altitude range is a good

approximation of the percentaga of strong reactions in the lower

altitude range.

of a group

is engaged

3. Reactivity of Groups of Caribou Engaged in Differe~ Activities:

The

of

in

hypothesis

caribou to

was tested.

that a relationship exists between the reactivity

aircraft disturbance and the activity the group

A chi-square test showed that at~the less than

. . . . • 0 • • • • -1 ••

. . . ,..., ·., li-· - . •

• •

' . '

•

··~··

- 189 -

- CESSNA 185 ~ 90 -z 0 1-1 H c..:>

r:l ~

~ 60 0

f;;l::l c..:> z f;;l::l

~ :::::> u C,) 0 30 ~ 0

~ (.) z f;;l::l

§. ~ ~ ~

<300' 301 ''-600' 601'-1000' >1000'

ALTITUDE

MILD

STRONG -BELL 206

90

60

30

<300' 301'-600' 601'-1000' >1000'

ALTITUDE

Figure 26: Reactions of caribou groups to disturbance from Cessna 185 and Bell 206 aircraft.

• •

•

..

- 190 -

300 ft. and 301 - 600 ft. altitude ranges the degree of reaction was not

independent o.f the. activity of the animals. At the 601 - 1000 ft. level

reactivity was independent of group activity. Insufficient data in the

greater than 1000 ft. altitude range precluded testing at this altitude.

The results of the comparison of reactivity vs. activity are found in

Table 39. A representation of the reactivity of caribou engaged in

various activities for the three altituae ranges is found in Figure 27.

The greatest reactivity, as shown earlier, occurs at the "less

than 300 ft." altitude range. Groups engaged in feeding reacted most

often to aircraft flying at this altitude level. Travelling groups,

then bedding, and standing ones followed. Groups that were bedded

shewed a high proportion of strong reactions and fewer of the mild

reactions. One possible explanation for this phenomenon is that the

threshold of disturbance for a strong reaction is close to the thres­

hold for the rousing of animals from the bedded position. This explana­

tion does not hold as well for altitudes greater than 300 ft.

The reactivity of caribou at the 301 - 600 ft. altitude range

was considerably less than at the "less than 300 ft." range. Eeeding

animals again showed the greatest tendency to react to aircraft dis­

turbance. Bedding animals were second in reactivity followed by the

"travelling" and "standing" categories. A small percentage of

animals reacted to the aircraft at the 601 - 1000 ft. range. A general

equalization itl reactivity between activity classes seemed to occur at

this altitude range.

In summation, the reactivity of a group of caribou is related

~o their activity. Feeding and bedded groups react most often, the

bedded group most intensely.

• •

I

•

,;.._ ' < I -""' ' ' ';. . " ' ' ' . ·l "'.). ' - . . "' . .

;I • t "t: . . ., . - ~ ... '* • • ,. = l I • ~ -, ' , -·-- . 't • * . -

•·

- .

Table 39: Comparison of the reaction of caribou engaged in four different activities to fixed-wing aircraft at three different altitude ranges.

ACTIVITY <300 I 300'-600' 600'-1000'

l·'JIL MILD STRONG NIL MILD STRONG NIL MILD STRONG -- - -Bed n 18 6 29 27 19 6 49 9 1 % 34 11.3 54.7 51.9 36.5 11.5 83.1 15.2 1.7

Stand n 6 7 1 9 2 2 20 7 0 % 42.9 50 7.1 69.2 15.4 15.4 74.1 25.9 0

Travel n 13 20 ;29 55 12 13 94 11 1 % 20.9 32.3 46.8 68.8 15 16.3 88.7 10.4 .9

Feed n 13 42 44 34 36 13 89 8 0 % 13.1 42.4 44.4 42.5 43.4 15.7 91.7 8"3 0

1-1 \0 1-1

,, \

90

...-. ~ 60 -· z 0 H :--. u ;J p:::l

p;., 30 0

~ C,) z 1".;1:::1

::::::> 0" ~ l::x:l ~

60

30

...-. 60 ~ -z 0 H E-1 C,)

;J ~ 30 ~ 0

~ C,)

~ § ga ~

BED

BED

BED

- 192 -

<300 ft.

STAND TRAVEL

301 ft - 600 ft.

STAND TRAVEL

601 ft. - 1000 ft.

·•·•·•·· ••••o••• •····••· :·:·:·:· ······•• ········ ········ ········ .... ···•··•• ····••·• ·.•:a•.•. ······•· •···•·•· :·:···:·

STAND TRAVEL

FEED

FEED

FEED

STRONG REACTIONS

MILD REACTIONS -

Figure 27: Reaction of caribou groups engaged in various activities to aircraft disturbance.

•

··.,--~-----T·--·~~· ,~~- ·-. -

'( ~

..

•

- 193 -

4. Reactivity of Caribou in Relation to Group Size:

Group sizes vary considerably, both within seasons and between

them. In order to assess the influence of group size on the reactivity

of caribou to airplane disturbance various ranges of group sizes were

compared. Data used were collected throughout the 1972 field season,

the majority arising from observations on the winter r~nge and spring

migrations. Only data collected in the Cessna 185 were used. The

results of 901 encounters are presented in Table 40. The data were

well distributed throughout the various altitude ranges, but a lack of

observations of groups larger than 500 animals existed.

In the "J.ess than 300 ft." altitude range, the tendency was

for the larger groups to be more reactive. In the 301 - 600 ft. altitude

range this trend disappeared, and may even have reversed somewhat. In

the 600 - 1000 ft. and "greater than 1000 ft." ranges no trends in the

relationship of group size to reactivity to aircraft were obvious. A

~hi-square test was done to determine whether the reactivity of the

caribou was statistically independent of the group size. Small sample

sizes in the higher group size ranges necessitated the lumping of groups

greater than 100 animals. Only in the "less than 300 ft." altitude

rang~ was the reactivity of the animals dependent on the group size.

As was stated earlier, the larger groups reacted most frequently and

most strongly. A graphical presentation of results is found in Figure 28.

5. Reactivity of Caribou in Relation to Seasonal Activity:

Variation in reactivity of caribou associated with a change in

the seasonal activity of the herd was investigated. Reactions to the

Cessna 185 aircraft 'tl7ere compared for winter range, spring migrations

and summer movements. The data appear in Table 41. Unfortunately the

skewed distribution of the data from the smruner movements precluded

the statistical comparison of this phase to winter and spring observations.

• a

"

•

•

. ..

:

!'·,;<

Table 40: Reactions of various sizes of groups of caribou to fixed-wing aircraft at dif­ferent altitudes.

-ALTITUDE <300 301• - 600 1

601' - 1000' > 1000 '· GROUP SIZE

NIL MILD STRONG NIL MILD STRONG NIL MILD STRONG NIL MILD srrRONG - - -1-9 n 30 39 31 35 29 10 31 1 1 7 2 1 % 30 39 31 47.3 39.2 13.5 93.9 3.0 3.0 70 20 10

10-49 n 23 32 50 50 27 14 59 11 0 33 4 0 % 21.9 30.5 47.6 54.9 29.7 15.4 84.3 15.7 89.2 10.8

50-99 n 6 17 14 15 12 2 14 2 0 13 3 0 % 16 .. 2 45.9 37.8 51.7 41.4 6.9 87.5 12.5 81.25 18.75

100-499 n 2 7 20 24 14 4 44 7 0 18 9 0 % 6.9 24.1 68.9 57.1 33.3 9.5 86.27 13.7 66.7 33.3

500-999 n 0 0 3 1 2 1 11 5 0 7 0 0 % 100 25 50 25 68.75 31o25 100

1000-5000 n 0 1 6 2 2 0 40 7 1 3 0 0 % 14.29 85.7 50 50 83.3 14.6 2.1 100

>5000 n 0 2 0 1 3 3 25 2 0 .5 1 0 % 100 14.3 42.8 42.8 92.6 7 .. 4 83.3 16.7

1-' \0 .p.

______ ,.., - *~~- ,,,_,__ . .....,_.,.__ - ~ ~..._. --~-----...., • ' lllllii

f' f f

I t i

•

•

•

• •

1-:rj

~ .0

~ n ~

0 1-:rj

0 n n

~ ~ n tL:I

,...... ~ "-J

~--·!-- -- .... -. ...

100

80

60

40

20

}--1 1-' IJ1 I-' IJ1 I-' v I OOOOOV1

\0 f I 0 0 00 .P..\01 I 00 \0 \0 .p.. \0 ! 0

\.0\.0lTI \.0 \0 0

0 0

<300 ft.

I-' I-' VI I-' IJ1 I-' V I OOOOOIJ1

\0 I I 0000 .p.. \0 I l 00 \0 \.0 .p.. \0 I 0

\0 \0 IJ1 \.0 \0 0

0 0

301 ft. - 600 ft.

1-'1-' I 0

\0 I .p.. \.0

STRONG REACTIONS -

MILD REACTIONS -

IJ1 1-' IJ1 1-' v 0 00 OlTI I 00 00

\0 I I 0 0 \.0 .p.. \.0 I 0

1.0 \0 IJ1 \0 \0 0

0 0

601 ft. - 1000 ft.

GROUP SIZES AND AIRCRAFT ALTITUDE

·: ·:·:· :· :· :·:·: ·:.:. :·:.:. ".•.•.•.• .. •.•.• .. • .. •.• .. • .. • .. •

1-'1-'lTI 1-' IJ1 1-' v 100 OOOV1 \01 I 0000

.P..\0 ! I 00 \.0 \0 +='- \.0 I 0

\0\0lTl \0\00

0 0

>1000 ft.

I-' \0 IJ1

~r:,

,., ) ~

i r I' \ i

Figure 28: Reactions of various sizes of groups of caribou to aircraft disturbance •

• -------------·- .. ,-u> f

•

~-----~- _irlr( --

. ..

r -

Table 41: Comparison of the reactions of caribou to fixed-wing aircraft during wirlter range, spring migration, and summer movements.

---··

<300' 301' _,. 600' 601' - 1000' >lOOO'

··----· NIL MILD STRONG NIL MILD STRONG NIL MILD srrRONG NIL MILD STRONG - -- --·- -

Winter Range n 30 41 42 31 38 7 13 2 1 16 0 0

%26.5 36.3 37.2 40.8 50 9.2 81.3 12.5 6.3 100 I-' \.0

Spring Migration n 16 84 47 78 43 20 82 0\

19 0 64 18 , .1.

%10.9 57.1 32 55.3 30.5 14.2 81.2 18.8 0 77.1 21.7 lo2 Summer Movements n 0 6 3 1 3 4 121 13 1 13 1 0

% ,66. 7 33.3 12.5 37.5 50 89.6 9.6 .7 92.9 7.1

•~fJ!H, ! &~JL.JlWIA) .. FJ(IJ:., A<.~~--~~.....-..-, -- ~" "'--"' ,.,..,. ,o.r __ ,.....,..., --- - •. __,

~- _,...,. -- - - ... .,.._. ~,1

-· '

I 1

..

•

•

- -- . . . .. - -~~- ·_: ____ --~ -- --- -.. -.- .. - ·--.-_- · . .- -- ·--·. --. ---~--~------' /

• • • • ~ ~ ,J

- 197 -

In general the reactivity of the caribou appeared to remain

fairly constant through the seasons. An increase in the "mild" reaction

category in the spring migration as compared to the winter range at the

less than 300 ft. altitude range is apparent. This is a result of a

high proportion of this response from observations made in the Richardson

Mountains. This trend is not apparent if only data from the Old Crow

Migration Route is considered, and hence, we are led to assume, is a

product of other factors (terrain etc4) rather than purely seasonal differences.

In the 301 - 600 ft. altitude range, animals on the winter

range reacted more often than those on spring migration. However, a

higher proportion of the responses in thf~ spring were of the "strong"

variety, and little overall difference in reactivity between the

seasons at this altitude level is concluded.

At the 601 - 1000 ft. altitude range, the reactivity of

caribou in the winter and spring was similar, but a slight decreasE~

in the sensitivity during the summer was evident. This decrease in

sensitivity may have resulted from insect harassment, which tends to

tire and distract caribou (Lent 1964). Data gathered at altitudes

exceeding 1000 ft. suggest a higher sensitivity during spring migration.

Once again this arises from observations in the Richardson Mountains,

and the increase in reactivity is probably in response to factors other

than purely seasonal considerations.

In general, no major seasonal differences in the reactivity

of caribou to disturbance from aircraft were observed. Unfortunately

data from the calving period was lacking. It has been suggested that

this period is characterized by heightened sensitivity to unusual stimuli (Lent 1964).

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6. Reactivity of Caribou in Relation to Habitat Type:

The isolation of the various features that characterize a

habita~ and the comparison of the reactivity of caribou among them

would require more data than was collected during this study. However,

an indication of the influence of habitat on reactivity of caribou to

disturbance is suggested in the following analysis .•

Two fairly distinct habitat types are the Richardson Mountains

and the wintering area and migration routes of animals passing Old Crow.

The major differences are:

(1) The Richardson Mountains present a more rugged topography.

Slopes a~e st·eeper aud peaks higher than along the Old

Crow Route.

(2) Except for the occasionally treed river valley, the

Richardson Me~untains are unforested, while most of the

Old Crow Route is in forest.

(3) Snow conditions vary .a great deal in the Richardson

Mountains, the higher areas being wind blown anti shallow,

the valleys often cove~ red with deep loose snow. Snow

conditions along the Old Crow Route are more constant

and deeper in comparison to the Richardson Mountains.

A comparison of the reactivi.ty of car:i.bou in these two habitat

types was made. Only observations made from the Cessna 185 during

winter and spring migration were compared. The data are presented in

Table 42. A graphical representation of the data is found in Figure 29.

The data from the two locales are basically similar with respect to the

frE:quency of reactions vs. non-reactions at the various altitude ranges.

A significantly larger proportion of the reactions at the less than 300

ft. altitude range in the Old Crow Route as compared to the Richardson

Nountains were in the strong category. Sampling bias may be involved

. . :,_; ·~q : . .• •' • t j\ ~ • • \. I} .. • • ..

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Table 42: Comparison of the reactivity of caribou in two different habitat types to fixed-wing aircraft.

LOCALITY 300' 301' - 600' 601' - 1000' lOQQi

NIL MILD STRONG NIL MILD STRONG NIL MILD STRONG NIL .MILD STRONG - -Old Crow n 35 79 73 80 67 15 35 12 1 34 0 l % 18.7 42.3 39.0 49.4 41.4 9.3 72.9 25 2.1 97.1 0 2.9

Richardson n 11 46 13 29 14 12 60 9 0 10 0 0 % 15.7 65.7 18.6 52.7 25.5 21.8 86.9 13.1 100

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100

80

60

40

210

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(") ~· (")

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601'-1000 1

;;d 0 :.0 H ~ H n (")

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STRONG REACTIONS -

MILD .... --............... ·.······ .·.~.-... <. ··················•····••············ REACTIONS - ·:::::::::::::::::::::::::::::::::::: ··················fll·.·.·." ... ···•·····

>1000'

0 !Ai t-1 H tj (")

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Figure 29: .~ comparison of the reactivity of caribou in different habitat types to airct.aft dit~rcurbance.

li?ii~& ,.?54 .14!. ~:MI.. ,..,. ,_...~- -~ ~~ -~ .... -. .._ --"""---"' ·-·--- --- .... ,.. . ----· ,,_, -·· -. ......... .-- - - . ._

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here, as the likelihood of spotting a caribou when flying low over

forested areas would be greater if the animal was moving. The numbers

~f strong responses decreased in the Old Crow segment while no such

cecrease occurred in the Richardson's at the 300 - 600 ft. altitude

range. This would indicate that the strength of response in the

mountainous areas is not as closely related to the strength of stimulus.

Data indicate that at altitudes over 600 ft~ the caribou have a higher

tendency to re3pond to aircraft disturbance in non-mountainous areas.

D. Summary of Results:

Data were gathered on the reactions of caribou to aircraft

throughout the course of the "spotcheck" survey flights, as incidental

information. The findings included:

1.

2.

3.

4.

Caribou reacted more strongly to Bell 206 helicopter than

Cessna 185 at low altitudes (less than 300ft.). No differ­

en~e in reactivity to different aircraft was found in the

data for altitudes greater than 300 ft.

The reactivity of caribou to aircraft disturbance decreases

as the altitude of the aircraft increases, up to an altitude

of approximately 1000 ft. Reactions to aircraft at altitudes

greater than 1000 ft. are unpredictable, but as a rule, infrequent.

Groups of car.ibou which were feeding or bedded reacted most

often to aircraft disturbance; the bedded animals most intensely.

A correlation between group size and reactivity to aircraft

was found only at altitudes belmv 300 ft. Larger groups

reacted most often and most intensely.

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6.

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Although data were incomplete for some seasons of the year,

no. outstanding changes in reactivity were observed betTJ~en

sea~ons.

Comparisons of data collected in two different habitat types~

the Richardson Mountains and Old Crow wintering and spring

migration route~, suggested that the reactivity of caribou

was basically similar between the two. The v·aria tion in the

reactivity with altitude differed in that th~ decrease in

the proportion of strong responses with increased altitude that

is obvious in the data for the latter habitat type, did not

occur in the mountains between the under 300 ft and 301 - 600

ft. altitude levels.

It is tonceded that the collection of data involved approximations

with ragard to altitude and a degree of subjectivity in classifying the

degree of response. Sample sizes are generally small especially at the

higher altitudes and data collected in the future will inc1.·ease the valid­

ity .of many of the interpretations.

E. Discussion:

The disturbance of caribou by aircraft is a major consideration

in the general disturbance of populations which could result from the con­

struction of a northern gas pipeline. Unfortunately information on the

response of caribou to aircraft in previous studies is very limited. Ob­

servations of the reactions of caribou under other circumstances to

various types of disturbance are, however, documented in the literature.

The disturbance of caribou by aircraft involves both auditory

and visual stimuli. The two aircraft types investigated in the present

study provided a good deal of v~riation in the nature of tbe sound

V produced and appearance in flight. It is difficult to assess which

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component of aircraft disturbance is most disturbing to the caribou, as

it is difficult to isolate situations where the stimulus is exclusively

auditory or visual.

The flight of large birds (eagles) over a caribou herd might

be considered analogous to the visual stimulus from aircraft. Lent (1964)

describes how golden eagles swooping low over ~ group of caribou caused

the animals to scatter wildly. Renewable Resources personnel had an

opportunity to observe four bald eagles making flights over groups of

caribou on the calving ground. The response of the caribou was a mild

escape reaction. It is possible that the reaction to visual stimulation

from the aircraft is derived in part from the response of the caribou to

predatory birds. Harassment of an animal by eagles could reinforce a

strong reaction to aircraft. It is unlikely that all or even most

caribou have been harassed by eagles and have learned to associate an

object in flight as a threat; however, the variability in the response

of different animals or groups may be a function of this factor.

Another situation where animals appear to react to a visual

effect of aircraft flight is the response to aircraft shadov1s. A report

by a bush pilot that animals were alarmed when the shadow of the aircraft

passed through the herd, when investigated further, indicated that

animals would react to the sight of the shadow, but only when its approach

was obvious for a considerable length of time (on a hillside).

Numerous observations of caribou reacting to auditory stimuli

alone were made. In low flights over forested areas animals often

reacted before visual contact between the aircraft and the animals was made.

As was mentioned earlier, the type and intensity of visual and

auditory stimuli emitted by a Bell 206 helicopter as compared to a Cessna 185

aircraft are different. Our results have shown that at altitudes below

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300 ft. the helicopter elicited a more severe reaction by the caribou

than did the Cess~a 185o However, at altitudes greater than 300 ft. the

differences in reactivity became negligible. An explanation of this

phenomenon could be based directly on variation in the intensity of the

stimulus. The difference in sound intensity of two sound sources would

diminish as distance from the sources increased. The same could be said

for the size of a visual stimulus. The additional strength of stimulus

required to elicit a strong response as compared to a mild one would

have to be less than the difference in intensity of one stimulus as

compared to another. For example, if the difference in the intensity of

noise emitted by a helicopter as compared to fixed-wing was 20 de~ibels,

and an increase of 10 decibels was required to promote a mild reaction

to a strong one, the strong response would be observed~ However, at

some distance away from the aircraft, where the difference in intensity

of noise between the two aircraft was only five decibels, no difference

in the intensity of ::.esponse could be e.xpected. Measurements of the

intensity of noise of different aircraft flying at different altitudes

were not made; therefore this discussion must remain largely hypothetical.

The same argument could apply to variations in the frequency and rhythmic

quality of the noise and visual stimuli. The length of time for which

the caribou are exposed to aircraft disturbance will influence the inten­

sity of their reactions. A helicopter hovering or flying very slowly

over a group of animals is more likely to stimulate strong reactions

them is rapid straight-line flight over the group by either helicopter

or fixed-wing aircraft.

The intensity of response of caribou to aircraft disturbance

was found to be inversely related to the altitude at which the aircraft

was flying. In other words, a direct relationship between strength of

stimulus and strength of response can be postulated. Since responses

were categorized, threshold levels for the stimulation of a response in

terms of altitude can be determined. To determine a thresh~ld level for

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a sample in which variation is found, it is necessary to define the

threshold leve~ as the point at which the probability of eliciting a

response with a certain strength of stimulus is greater than 50%. Thres­

hold levels for mild and strong r,esponses in the Cessna 1S5 differ from

those in the case of the Bell 206. The threshold for mild and strong

responses in terms of altitude for the Cessna 185 would be approximately

500 ft. and 200 ft. re~pectively. The threshold for mild and strong

respons~s for th~ Bell 206 would approximate 500 ft. ancl 300 ft.

A thzeshold level must not be confused with an acceptable

disturbance tolerance level. The defit1ition cf a tolerance level

usually involves qn arbitr~ry level of stress based on energy expend­

iture or some other indices.

The definition of a tolerance level, exprsssed as an alt~,.tude

which is re~s0uable in terms of disturbance to caribou and realistiG in

terms of aircraft operation, is necessary. 'ine invfrse relationship of

frequency and strength of responses to aiJ.";craft ::1ltitude is maintained

to ~n elevation of approximately 1000 ft. At altitudes greater than

100-!0 ft., the re!activity of caribou· is somewhat unpredic ~able, but

uevertheles$ very infrequent. As a result, 1000 ft. is suggested as

a minimum altitude tolerance level.

Tne relationship between the reactivity of caribou to distur­

bance and the acti-vity in '\vhich they are en,gaged has not been discussed

to any length in the literature. A comparison of the responses of groups

of caribou i~ similar situations (altitude etc.) indicated tnat the

reactivity oi caribou was not independent 1'\f activity.. FPn.ding caribou

seemed to re~ct most often and bedding animals most intensely.

Several observations were made where caribou were being harassed by wolves

and bears. In these circumstances the caribou seemed to concentrate on the aet­

ivities of the predator, and no additional stress from the presence of

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the aircraft was uoted, suggesting perhaps that in some cases caribot.l will

filter out. norma·lly disturbing stimuli because they are preoccupied with

some other activity.

An argument somewhat along the same line could be applied to

the apparent differences in the sensitivity between travelling animals

and feeding and bedded ones. Movement of caribou through habitat which

is largely unfamiliar might result in an increase in the threshold for

disturbance, including aircraft disturbance. Animals feeding and bedding •

in surroundings which are somewhat familiar, merely because they have

spent a longer period of time in one place, would have less frequent

contact with disturbing stimuli and would react more strongly when

disturbed.

The variation in the reactivity of caribou to aircraft dis­

turbance according to group size was investigated. There is a large

variation in group sizes within any particular season as well as large

seaEv~~al varjation. Lent (1964), Murie (1935), Banfield (1954) and

Kelsall (1957) commented about the unwary behavior of caribou in large

aggregations. Lent (1964) stated that lone caribou are more sensitive

to noises. Lent (1964) hypothesized that Pnimals in a large herd do not

react ;:;.s strongly due to the "repetitive stimulation" the animal

receives from the large number of animals in proximity to it. In other

words, the abundance of noise and motion associated ~-lith a large group

should increase the threshold to disturbance by another stimulus. This

theorum did n_at .seem to apply in the case of aircraft disturbance.

Larger groups, in fact, reacted more strongly to aircraft disturbance.

One possible explanation might be that in large groups more animals

receive the disturbing stimulus because of its overhe~d source, and

the transfer of alarm reactions between an~.mals is mo:r;e efficient due

to the compact nature of these groups. The ~ifferences according to

group size are not found at altitudes over 300 ft.

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The changes in social structure, physical and biological

environment, behavioral motivation, physiological cQndition and sensory

ca.pat::itites between seasons suggest that accompanying changes in the

~eactivity of caribou to aircraft differences shouM result. Lertt (1964)

states that the greatest difference arises in cows with calves between

the calving period and summer movements. Unfortunately few data were

collected during the calving period and this comparison could not be

made. Lent (1964) suggested that caribo~'!J~ are most sensitive to sounds

in the wiuter when temperatures are below -20° C. He also states that

caribou are more sensitive to movement during the winte~, and suggests

this sensitivity is a compensatory mechanism for the inability to

detect odors. Comparisons of reactions of caribou in different seasons

(winter, spring and summer) did not reveal any outstanding seasonal

diffe~ences. It is possible that the classification of responses into

only three categories was insufficient to detect the. magnitude of

changes that could have occurred.

A comparison of two physical habitat types (i.e. mountainous

vs. non-mountainous o~ forested vs. non-forested) did not reveal a con­

sistent trend at different altitude ranges. The outstanding feature of

this comparison was the fact that the direct relationship between strength

of stimulus and strength of response in the non-mountainous area did

not apply as well in the mountainous area. This is likely a product, at

least to some degree, of the inconsistency of acoustic reception in

different positions on the mountains. It is possible that the relation­

ship of the strength of stimulus to strength of response was intact, but

the relationship of altitude to strength of stimulus was inconsistent.

Ber,gerud (1971) notes that when caribou take flight they norm­

ally move toward open habitat:, suggesting that open habitat is favored

escape terrain. Animals in the Richardson Mountains therefore could

be expected to be less wary because they were already in prime escape

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terrain. Unfortunately the inconsistency of the data as mentioned

earlier preclude.s judgement on this hypothesis.

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