EVALUATING WELFARE OF AMERICAN BLACK BEARS (URSUS AMERICANUS) CAPTURED IN FOOT SNARES AND IN WINTER DENS - Oxford Academic ...
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Journal of Mammalogy, 86(6): 1171-1177, 2005
EVALUATING WELFARE OF AMERICAN BLACK BEARS
(URSUS AMERICANUS) CAPTURED IN FOOT SNARES
AND IN WINTER DENS
ROGER A. POWELL
Departments of Zoology and Forestry, North Carolina State University, Raleigh, NC 27695-7617, USA
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Much research on wild mammals requires trapping, especially Iivetrapping, yet few methods used to capture wild
mammals have been tested against an accepted standard for animal welfare and few data exist regarding
physiological responses to capture. My coworkers and I livetrapped 208 American black bears (Ursus
americanus) 356 times between May 1981 and August 2001 in the Pisgah National Forest in the Southern
Appalachian Mountains by using Aldrich-type foot snares modified for bear safety with automobile hood springs
and swivels spliced into cables. We outfitted most bears with transmitter collars and followed 18 bears to their
winter dens. We outfitted 8 bears with transponder collars mounted with remotely dischargable darts loaded with
anesthesia. We recorded the physical injuries of all bears handled and obtained 186 standard blood chemistry
profiles from 112 bears. I compared the blood chemistry profiles of snared bears to profiles of bears in dens, to
profiles for healthy, captive bears, and to profiles for wild bears that were collar-darted. Aldrich-type foot snares
modified for bear safety, as we used them, and den handling met the accepted standard for trap injuries. Blood
chemistry profiles indicated that bears captured in snares experienced high levels of physical exertion and were
dehydrated. Blood chemistry parameters responsive to exertion increased with increasing injury scores.
Key words: animal welfare, bear, creatine kinase, lactate dehydrogenase, serum blood chemistry, snare, trap, Ursus
americana
How animals are trapped and the impacts of trapping on is 50 points, above which an animal has received unacceptable
animal populations are major societal concerns (Proulx and injury. Similar scoring patterns have been proposed since
Barrett 1989) and traps that have minimal effects on animals (reviewed by Proulx 1999). Powell and Proulx (2003) adopted
minimize aberrant effects on behavior and ecological data. Yet, a criterion for assessing live traps that is consistent with the
few traps have been tested against standards (Powell and accepted standards for killing traps (Canadian General Stand-
Proulx 2003; Proulx 1999). Traps used in research should meet ards Board 1984; Powell and Proulx 2003; Proulx and Barrett
perfonnance criteria that address state-of-the-art trapping 1994): State-of-the-art live traps should with 95% confidence
technology and that optimize animal welfare conditions within render '2:70% of animals caught with -:;50 points scored for
the context of the research (Powell and Proulx 2003; Proulx physical injury.
1999; Proulx and Barrett 1994). In addition to injuries from traps, mammals respond to
Much research on wild mammals uses live, or restraining, capture behaviorally and physiologically (Cattet et al. 2003;
traps. Very few restraining traps have been tested against Kreeger et al. 1990; Proulx et at. 1993; Seddon et al. 1999;
standards for animal welfare (Proulx 1999). Tullar (1984) and Warburton et al. 1999; White et al. 1991). Cattet et al. (2003)
Olsen et at. (1986) developed systems to score injuries caused compared blood chemistries of grizzly bears (Ursus arctos)
by live traps. Olsen et al. (1986) proposed that each bruise, darted from helicopters to those of bears captured in foothold
minor cut, or minor joint damage be scored between 5 and snares. Warburton et al. (1999) noted that blood chemistry of
50 points, depending on its extent; serious injuries each be silver-gray brush-tailed possums (Trichosurus vulpecula) cap-
scored >50 points; and severe injuries be scored> 125 points. tured in soft-catch-type foothold traps differed from that of
They proposed that an acceptable, threshold sum for all injuries possums captured in cage traps and from captive animals. To
date, no objective scoring system for live traps combines
injuries with behavioral and physiological responses (Powell
* Correspondent: newf@ncsu.edu and Proulx 2003; Proulx 1999), at least in part because inter-
preting behavioral and physiological responses is not straight-
© 2005 American Society of Mammalogists forward (Dawkins 1998). Perhaps because responses are
www.mammalogy.org confusing, researchers avoid publishing data. The consequence
11711172 JOURNAL OF MAMMALOGY Vol. 86, No.6
TAIlU; t.-Scoring system for injuries received by bears during Powell [2003], Mitchell and Powell [2004], and Powell et al. [1997]).
capture. Scores are those ofObon et al. (1986) unless an injury was The study area was the 220-km2 Pisgah Bear Sanctuary, located in the
not scored by that system, in which case the score was that of Hubert Pisgah National Forest approximately 35 km southwest of Asheville,
et ai. (1996) and is marked with an asterisk (*). North Carolina (35°28'N, 82°40'W) in the southern Blue Ridge
Mountains of the southern Appalachians. Elevations ranged from 650
Injury Seore to 1,850 m. Annual rainfall often exceeded 200 em and fog frequently
Edematous swelling and hemorrhage 5 enveloped high elevations. Hardwoods, such as oaks (Quercus),
Avulsed claw (claw removed exposing pulp)* 5 hickories (Catya), tulip poplar (Liriodendron tulipijera), and maples
Cutaneous laceration < 2 cm length 5 (Acer); and pines (Pinus) and hemlocks (TsuKa) were the most
Pennanent tooth fmclure exposing pulp* 10 abundant trees.
Cutaoeous lacemtion > 2 cm 10 We trapped bears predominantly by using Aldrich-type foot snares
Tendon or ligament laceration 20 modified with automobile hood springs to provide cushioning for
Joint subluxation 30
trapped bears (Johnson and Pelton 1980). When a trapped bear
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Joint luxation 50
reached the end of its cable, which was bolted to a tree, cushioning
Compression fracture above or below earpus 30
Simple frU(;ture at or below carpus or tarsus 50 from the hood spring prevented the bear from receiving an abrupt jolt.
Compound facture at or below carpus or tarsus 75 We took care to set snares where bears could not tangle their cables
Simple fracture above carpus or tarsus 100 around small trees and shrubs, thereby negating the cushioning effect
Compound fracture above carpus or tarsus 200 of the hood spring, and we took care to set snares where bears would
Amputation of digits
be shaded during daytime. We set snares predominantly 100-300 m
from backcountry trails, some snares were set more than 6 km from
1 digit 50
2 digits 100 trailheads, and we baited snares with sardines, meat scraps, or old
3 digits 150 pastries. We checked traps each morning and handled bears promptly
4 or 5 digits 200 after all traps had been checked. However, when 2 or 3 bears were
trapped on I day, a bear or bears sometimes remained in traps into the
Amputation above digits 400
afternoon. When faced with multiple captures, we handled bears in
an order that minimized total time for handling all bears with the
is that, with few data, understanding behavioral and physio- constraint that bears that appeared stressed were handled first.
logical responses to capture is delayed. We immobilized bears with a mixture of ketamine hydrochoride and
Here I evaluate the physical injury and blood chemistry xylazine hydrochloride (approximately 200 mg of ketamine and 100
responses of American black bears (Ursus amerh·anus) mg of xylazine per milliliter) administered with a jab stick or blowgun
captured in Aldrich-type foot snares modified for bear safety at a dosage of I ml/25 kg estimated weight. We monitored vital signs
and of bears handled in their winter dens. In addition, I com- during handling (body temperature, pulse rate, and respiration rate);
we cooled with water and ice the few bears that overheated and we
pare the blood chemistries of captured bears to those of captive
warmed the few bears that became cooled by wrapping each in a space
bears and free-ranging, wild bears drugged remotely via a dart
blanket, sometimes by wrapping a researcher in the blanket with the
mounted on a radiocollar. Specifically, I tested the following
bear. We gave all bears ear tags and tattoos, took standard measure-
hypotheses. Hypothesis 1: Injury scores for bears captured in ments, extracted an upper PI tooth to estimate age by counting
snares modified for bear safety and for bears handled in their cementum annuli, and drew blood from the femoral vein. Bears were
winter dens meet the accepted standard for humane live considered to be adults when >3 years of age; 2-year-old females who
capture. Hypothesis 2: Injury scores differ among groups of bred and produced cubs the following winter also were considered
bears. Specifically, I derived the following hypotheses from to be adults. We outfitted adult bears and some juvenile bears with
field observations: Hypothesis 2a: Injury scores for snared transmitter collars, according to research goals at the time of capture.
juvenile bears are greater than those for adult bears. Hypothesis In winter, when possible, my coworkers and I followed bears with
2h: Injury scores do not differ between the sexes for snared transmitter collars to their dens, which were hollow trees, hollow logs,
bears. Hypothesis 2c: Injury scores for snared bears are greater small caves, or open nests on the forest floor (Powell et a1. 1997). We
approached dens quietly and slowly, being careful not to disturb the
than those for bears handled in their winter dens. Hypothesis 3:
bears or to flush them. We immobilized bears in accessible dens by
Physiological responses of bears captured in snares modified
using a blow dart or jab stick, changed their collars if necessary, and
for bear safety indicate exertion and dehydration. Hypothesis 4: drew blood. We monitored vital signs as done during summer. In 1989
Physiological responses indicative of exertion and dehydration and 1990, we outfitted adult bears with 800-g transponder collars
increase with increasing injury scores. (3M, St Paul, Minnesota, and WildJink, Brooklyn Park, Minnesota-
I want to stimulate other field biologists to subject their Delgiudice et al. 1990) mounted with darts containing Telazol at a
methods of handling animals to scrutiny and to report what dosage of 5 mg/kg bear weight. I anesthetized bears wearing dart collars
they learn, whether their methods meet objective standards or remotely when their transmitter signals indicated that they were mildly
not. We cannot improve our methods systematically until we active and were confining their movements to a small area estimated to
know how they compare to objective standards. be ~800 m away (Powell et al. 1997). Mildly active bears were unlikely
to travel long distances before they could be found in the woods; they
were never seen before their darts were discharged remotely.
MATERIALS AND METHODS All injuries to bears were recorded in the field. I scored injuries
Between May 1981 and August 2001, my coworkers and I (Table 1) from data sheets by using the scoring system of Olsen et a1.
livetrappcd black bears for research related to ecology, animal (1986) unless an injury could not be scored by that system, in which
behavior, and wildlife management (summarized by Kovach and case I used the system of Hubert et al. (1996). Olsen et a1. (1986)December 2005 POWELL-EVALUATING WELFARE OF CAPTURED BEARS 1173
TABLE 2.-Blood chemistry result'>. The 2nd column states whether a blood parameter was grouped as responsive to exertion (E) or dehydration
(D) in multivariate analyses. The remaining columns list values for 112 bears captured 186 times in the Pisgah Bear Sanctuary during 1984--1996
and reference values for captive bears from the International Species Inventory System (ISIS). Both the exertion and the dehydration blood
chemistry groups differed significantly in group values between adult and juvenile bears, and between both adult and juvenile bears and darl-
collared bears.
Snared Snared Snared Denned
bears-all bears-adult bears-juvenile
"'= ISIS
Blood parameters Group x ± SD x± Sf) x ± SD n X±SD n X±SD 11 X±SD
Serum sodium (mmoVliter) o 141 ± 5 167 141 ± 5 80 141 ± 5 87 139 ± 5 7 136 ± 3 6 139 ± 4 119
Serum chloride (mmol/liter) o 104 ± 6 167 104 ± 6 80 104 ± 6 87 101 ± 4 7 103 ± 5 6 104 ± 5 !OI
Total serum protein (gJdl) o 7,1 ± 0.6 166 7.3 ± 0.6 80 7 ± 0.5 86 7.9 ± 0.4 7 7.6 ± 0.6 6 7.6 ± 0.6 126
Albumin to globulin mtio o 1.4 ± 0.4 166 1.3 ± 0.3 '0 1.4±0.4 86 1.3.±0.3 7 0.7±0.1 6 1.2
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Total serum bilirubin (mg/dl) o 0.2 ± 0.2 166 0.2 ± 0.2 80 0.3 ± 0.2 860.2±0 60.3±0.1 6 0.2 ± 0.2 99
Serum glucose (mg/dl) 0, E 170 ± 43 167 175 ± 43 80 165 ::!: 44 87 125 ± 56 7 83:!:: 35 6 102 ± 37 134
Serum albumin (gJdl) D,E 4 ± 0.5 166 4.1 ± 0.5 80 4 ± 0.5 86 4.5±0.5 7 3.2±0.1 6 4.1 ± 0.5 !O3
Serum CO 2 (mmol/liter) E 22 ± 4 167 23 ± 4 80 22 ± 5 R7 20 ± 5 7 21 ± 5 6 19 ± 5 39
Alkaline phosphatase (lU/liter) E 54 ± 35 166 35 ± 22 79 72 ::!: 36 87 12 ± 5 7 55±22 6 29 ± 19 109
Alanine aminotransferase
(IU/liter) E 101 ± 93 167 96 ± 99 80 106 ± 87 87 18 ± 8 7 29±5 6
Lactate dehydrogenase
(IU/liter) E 2,024 ± 2,021 166 1,693 ± 1,949 80 2,332 ± 2,048 86 574 ± 325 7 598±92 6644±356 45
Creatine kinase (lU/liter) E 10,720.± 17,839 162 9,299 ± 19,008 78 12,038::!: 16,688 84 328 ± 272 7 133 ± 34 6 151 ± 121 60
Serum cholesterol (mg/dl) E 282 ± 50 166 271 ± 50 80 293 ± 48 86 265 ± 76 7 296 ± 39 6 268 ± 68 107
Serum triglycerides (mg/dl) E 268 ± 108 166 250 ± 104 80 284 ± 109 86 222 ± 86 7240±77 6 234 ± 78 50
Amylase (IU/liter) E 57.2 ± 49.2 41 49.5 ± 36.7 19 63.9 ± 57.9 22 17:!:: 13 6 22 ± 15 46
Serum pota~sium (mmol/liter) 4.5 ± 0.5 167 4.4 ± 0.5 80 4.5 ± 0.4 87 4.5 ± 0.4 7 4.9 ± 0.4 6 4.6 ± 0.4 II'
Blood urea nitrogen (mg/dl) 14 ± 7 167 12 ± 5 80 16 :±. 8 87 7 ± 4 7 21 ± 8 6 20 ± 13 121
Serum creatinine (mg/dl) 1.4 ± 0.5 167 1.6 ± 0.5 80 1.2 ± 0.4 87 2.8 ± 0.5 7 1.2 ± 0.3 6 2 ± 0.6 118
Serum uric acid (mgldl) 1.6 ± 1.3 166 1.3 ± 0.7 80 1.8 ± 1.6 86 2.6 ± 2.2 7 0.7 ± 0.3 6 1.4 ± I 114
Calcium (mg/dl) 8.7 ± 0.8 167 8.5 ± 0.9 80 8.8 ± 0.8 87 8.5 ± I 7 8,2 ± 0,6 6 9.3:!: 0.6 126
Serum phosphorus (mgJdl) 4.6 ± 1.8 166 3.8 ± 1.2 80 5.3 ± 1.9 86 3.7 ± 0.7 7 5 ± 0.8 6 5.6 ± I II'
Direct bilirubin (mg/dl) 0.1 .± 0.2 165 0.1 ± 0.1 80 0.1 :!: 0.2 85 O±O 6 0.2±0.1 6 O±O.I 34
Indirect bilirubin (rug/dl) 0.1 .± 0.2 164 0.1 ± 0.2 79 0.2 :!: 0.2 850.2±O 6 O.I±O.I 6 0.2±0.2 34
Gamma-glutamyltransferase
(lU/liter) 14 .± 9 163 15 ± 9 78 13 ± 8 85 8± 5 7 17 ± 5 6
Aspartate aminotransferase
(lU/liter) 589 ± 847 166 522 ± 832 80 652 .± 861 86 62 ± 16 7 85 ± 15 6
Serum iron (mg/dl) 128 ± 66 152 131 ± 58 67 125 ± 72 8520±44 8 144 ± 67 5 167:!: 98 17
developed their scoring system by performing necropsies on comparison, I obtained 2 sets of reference chemistry profiles. First, I
kill-trapped animals, whereas we closely examined live animals for obtained profiles (mean, SD, and sample size) for captive black bears
injuries. Because we would have missed some injuries obvious only through the Intemational Species Inventory System (ISIS; Table 2).
from necropsy, my scores are biased low by an unknown, but presum- When the mean reference (ISIS) value for a blood parameter differed
ably small, amount. I used the scoring system of Olsen et al. (1986) by 2 SDs from the mean value obtained for wild bears (either ISIS SD
because it is objective, because it is well known, because it can be used or wild SD), I considered the difference significant. I used this criterion
to score injuries of live animals, and because researchers need an a priori because only summary statistics were available from ISIS (original
set of measures to assess injuries to animals captured alive (Powell and data for each bear were not available). Because the distributions of
Proulx 2003). My coworkers and I treated all injuries as well as possible some pammeters are not normal, reporting medians and quartiles
under field conditions; our research team included at different times would be preferred were the ISIS data available in that fonnat. Second,
veterinarians, veterinary technicians, and veterinary students. Our I used as reference the profiles for bears darted remotely by using darts
research was approved by the Institutional Animal Care and Use mounted on transponder collars. I compared these blood chemistry
Committees of North Carolina State University and Auburn University, profiles to those of bears captured in snares and handled in dens. These
and was in accordance with the principles and guidelines of the bears that were darted remotely in the wild should have had blood
American Society of Mammalogists (Animal Care and Use Committee chemistry profiles representative of mildly active, wild bears.
1998) and of the Canadian Council on Animal Care (1984,1993). To avoid multiple cases of spurious significance when testing
I used the general linear model of SAS (PROC GLM-SAS multiple hypotheses on many blood parameters, I used multivariate
Institute Inc. 1999) to test for differences in injury scores among bears Kruskal-Wallis tests (multivariate analysis of variance [MANOVA1
of different maturity and sex. Each capture was then scored binomially option PROC GLM on ranks-SAS Institute Inc. 1999). For these
as being "Acceptable" (score ::; 50) or not. The exact lower 95% analyses, I grouped together those blood parameters expected to
confidence limit was calculated for the binomial probability that a respond to exertion and dehydration (Kaneko 1989; Table 2). The
bear's injury score was "Acceptable." exertion group included serum albumin, alanine aminotransferase,
Blood chemistry profiles were generated using standard methods at amylase, alkaline phosphatase, cholesterol, CO 2 , creatine kinase,
Mission Memorial Hospital, Asheville, North Carolina (Table 2). For glucose, and lactate dehydrogenase, whereas the dehydration group1174 JOURNAL OF MAMMALOGY Vol. 86, No.6
TABLE 3.-Injury scores for black bears of different age and TABLE 4.-Blood chemistry pararneters a with significant contrasts.
maturity classes. Bears were captured in foothold snares modified for Blood parameters known to respond to exertion or to dehydration
bear safety and were handled in their dens. To meet accepted standards differed as groups between adult and juvenile bears, and between
for animal welfare, a method of capture should have an injury score :S; bears trapped in snares and free-ranging bears wearing dart collars
5070% of the time with 95% confidence. The far right column shows (multivariate analysis of variance). The individual parameters that
the lower 95% confidence limit for the probability that injury score contributed those significant differences (least significant differences
will be :S;50 for each method of capture as used in this study. Both means test, general linear model procedure of SAS-SAS Institute
foothold snares modified for bear safety and den handling met the Inc. 1999) are listed below along with individual parameters that
criterion during this study. differed between snared bears and captive bears, between denned
bears and free-ranging bears, and between free-ranging bears and
95% lower
captive bears. ISIS stands for blood profiles for captive bears provided
confidence limit
that injury score
by the International Species Inventory System.
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will be ::;50
Blood chemistry parameters
Number (must exceed
Score with ~ignificant contrasts
Capture with score 70% to be
technique SO' Maturity X ± SD N :S 50 (%) acceptable) (%) Exertion Dehydration All
Foothold All bears 8 ± 15 340 334 (97) 94 Comparison parameters parameters parameters
snare Female Adult 7 ::':: 9 84 Snared adults versus AP, ALT, TP
Female Juvenile 10 ± 12 70 LDH, CK, Tri
juveniles
Male Adult 8 ± 8 61
All snared bears Glu, Alb, AP, Glu, Alb,
Male Juvenile 10 ± 21 125
versus dart collared ALT,LDH,CK NG,TP
IX" All bears 1.4 ± 2.3 18 18 (\00) 81
Snared adults Glu, Alb, ALT, Na, Glu,
handling
versus dart collared LDH,CK Alb, A/G
Snared juveniles Glu, Alb, ALT, Na, Glu,
included albumin, albumin to globulin ratio, Cl, glucose, Na, total versus dart collared LDH, CK Alb, AJG
bilirubin, and total protein. Because some bears were captured more All snared bears LDH, CK,
versus ISIS Amy
than once, I tested for an effect of individual bears and would have
Snared adults versus ISIS LDH,CK
blocked tests had it been necessary. Where MANOVAs found LDH,CK,
Snared juveniles
significant variation for blood parameter groups, I tested individual versus ISIS Amy
blood chemistries by using analyses of variance (ANOVAs) to find Denned bears versus Alb, AP AP
those responsible for the significance. Because I perfonned many dart collar
ANOV As, I set statistical significance at P = 0.01 to be conservative Denned versus ISIS BUN, UA,
and to avoid spurious acceptance of significance. Finally, I regressed P, AP
the values for each blood parameter against the injury score for each Dart coUar versus ISIS UA,Alb
bear captured by snare (PROe REG-SAS Institute Inc. 1999). a Alb: alhumin; A/G: alhumin to globulin ratio; ALT: alanine aminotransfera;e;
Hypotheses 1-4 were the null research hypotheses and were Amy: amyla!;e; AP: alkaline phO!;phatase; BUN: blood urea nitrogen; CK: creatine kinase;
developed from field experience before data sheets were scored for Glu: glucose; LDH: lactate dehydrogenase; Na: sodium; Tri: triglycende,; VA: uric acid.
injuries and before blood data were analyzed. For SAS and other
non-Bayesian statistical software, however, hypotheses 1-4 are con-
sidered to be alternative hypotheses to a statistical null hypotheses Injury scores for snared bears exceeded those for bears handled
assuming "no effect." Biological null hypotheses, however, represent in their dens (F ~ 16.94, df ~ 1,390, P < 0.01; Table 3).
standard knowledge and are the nonn against which alternative Aldrich-type foot snares modified for bear safety and
hypotheses should be tested. To test my biological null hypotheses handling bears in dens both met the standard of being 95%
by using conventional statistics, I used and report the probability of confident that injury scores will be :::;50 points for ~70% of
lype II error for the tests of the statistical null hypotheses (F-values captures (Table 3). The 95% lower confidence limit was 94%
and degrees of freedom are given for the type I error of conven- of captures for modified Aldrich-type foot snares and 81 % of
tional statistics). captures for den handling (both well above 70%).
Between January 1984 and August 1996, my coworkers and
RESULTS I collected blood samples from 112 bears (66 males and 46
females) captured 186 times (171 times in snares, 8 by dart
My research team and I livetrapped 208 black bears (125 collars, and 7 in dens). Means (± SD) for all blood chemistries
males, 81 females, and 2 sex unknown) 366 times (340 in are given in Table 2. Blood chemistry profiles for male and
snares, 8 by dart collars, and 18 handled in their dens). Exertion female bears did not differ for either blood chemistry group
and dehydration occurred during some captures and appeared (exertion or dehydration), nor did blood chemistry profiles
to differ by capture method. Bears captured in snares often differ for lactating compared to nonlactating females.
struggled vigorously to escape, whereas bears handled in dens Individual values for amylase, creatine kinase, and lactate
and collar-darted did not struggle. Bears captured in snares dehydrogenase were high for bears captured in snares
were sometimes without water for hours, whereas collar-darted compared to the ISIS values (Tables 2 and 4). In addition,
bears were normally hydrated. albumin and uric acid values were low for collar-darted bears
Injury scores did not differ among snared bears of different compared to ISIS values; and alkaline phosphatase, blood urea
sex and age classes (F = 0.64, dj. = 3, 388, P» 0.05; Table 3). nitrogen, and serum phosphorus values were low for bearsDecemher 2005 POWELL-EVALUATING WELFARE OF CAPTURED BEARS 1175
captured in their dens. However, levels for den capture were Nonetheless, the struggling of juvenile bears did affect their
confounded by occuning only in winter, whereas ISIS values blood profiles, leading to higher exertion and more dehydration
were taken during summer for active bears. The differences than shown by adults (Table 2).
between ISIS and den blood chemistry profiles highlight the I accept hypothesis 3. Bears captured in snares had blood
differences in renal function between active and denning bears parameter values that differed from values for captive bears and
(Nelson et al. 1973, 1983, 1984). from values for free-ranging, wild bears darted remotely
The blood chemistry profiles in the exertion blood chemistry (Tables 2 and 4). ISIS values for amylase, creatine phospho-
group differed among individual bears, differed by maturity kinase, and lactate dehydrogenase differed from those of snared
Uuveniles compared to adults), and differed between the sexes bears, consistent with higher activity levels and some de-
(for all P < 0.01). MANOVAs testing for effects of both hydration by bears in snares. Snared bears differed significantly
individual bears and maturity and testing for effects of both sex from collar-darted bears in their exertion and dehydration
and maturity showed that the significance found by testing for profiles. In addition to differences in creatine kinase and lactate
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effects of individual bears and sex alone was actually caused dehydrogenase identified in comparisons with ISIS values,
by differences in maturity. Consequently, subsequent tests for values for glucose, albumin, total protein, alkaline phosphatase,
differences were blocked for maturity effects. and alanine aminotransferase differed between snared bears
Both exertion and dehydration profiles for bears captured in and collar-darted bears.
snares differed between adults and juveniles (exertion: F = 9.93, Blood chemistry results were consistent with my anecdotal
df ~ 9,161, P < 0.01; dehydration: F ~ 4.01, df ~ 7,163, P < observations of captured bears: bears struggled in snares and
0.01; Tables 2 and 4), differed between snared bears and collar- some struggled vigorously. Bears that were collar-darted
darted bears (exertion: F ~ 4.65, df ~ 9, 168, P < 0.01; remotely were usually found in the woods as though they had
dehydration:F~ 7.33,df ~7, 170,P < 0.01; Tables 2 and 4), simply lain down to sleep but in a position so as not to
differed between snared adult bears and collar-darted bears roll downslope. Bears captured in snares contrasted with
(exertion: F ~ 9.93, df ~ 9,161, P < 0.01; dehydration: F ~ collar-darted bears by having elevated values for alanine
4.01, df ~ 7, 163, P < 0.01; Tables 2 and 4), and differed aminotransferase, alkaline phosphatase, creatine kinase, lactate
between snared juvenile bears and collar-darted bears (exertion: dehydrogenase, glucose, albumin, and albumin to globulin ratio,
F ~ 5.23, df ~ 9, 87, P < 0.01; dehydration: F ~ 2.92, df ~ 7, reflecting exertion and dehydration (Tables 2 and 4). In addition,
89, P < 0.01; Tables 2 and4). The statistical significances among alanine aminotransferase, creatine kinase, and lactate dehydro-
these profiles were caused by individually significant differences genase all increased with increasing injury scores, indicative of
in albumin, alanine aminotransferase, alkaline phosphatase, exertion. The high levels of aspartate aminotransferase with high
creatine phosphokinase, glucose, lactate dehydrogenase, and injury scores could be an artifact of high levels of lactate
triglycerides for exertion; and albumin, albumin to globulin ratio, dehydrogenase, which confounds the aspartate aminotransferase
glucose, Na, and total protein for dehydration (Table 4). test (Kaneko 1989). Bears captured in snares also contrasted
Five blood parameters increased with increasing levels of with collar-darted bears in level of dehydration by having
injury: alanine aminotransferase, aspartate aminotransferase, elevated values for albumin, albumin to globulin ratio, total
creatine kinase, glucose, and lactate dehydrogenase (P < 0.05 protein, and glucose (Tables 2 and 4).
for each). Of these significant parameters, alanine aminotrans- I accept hypothesis 4. Creatine kinase, lactate dehydroge-
ferase, creatine kinase, glucose, and lactate dehydrogenase nase, glucose, and alanine aminotransferase all increased with
were included in the exertion group. increasing injury scores, indicating that increased exertion led
to increased injury.
The exertion and dehydration profiles showed that adult
DISCUSSION
bears captured in snares exerted themselves less and were less
I accept hypothesis 1. Modified Aldrich-type foot snares, as dehydrated than juveniles. This result is consistent with the
used by my research team, and handling bears in their winter anecdotal observations that young bears struggled more in
dens met the accepted standard for injuries due to capture snares, even though juvenile bears did not have significantly
(Powell and Proulx 2003): we can be 95% confident that higher injury scores.
captured bears will have injury scores::; 50 points in 270% of General discussion.~Blood chemistry profiles from ISIS for
captures. These statistical results are so strong that the potential captive bears and for collar-darted, wild bears were similar,
bias (from scoring live bears, not doing necropsies) in my injury differing only in serum uric acid and albumin levels. Even
scores appears not to have affected the overall assessment of though the sample size for collar-darted bears was small, use of
capture methods. Table 3 shows that acceptable injury scores the blood chemistry profiles of these bears for comparison
should be obtained well in excess of 70% of captures. appears sound, especially because these bears were wild, free-
I accept hypotheses 2b and 2c but cannot accept hypothesis ranging, and naturally active.
2a. Injury scores for bears captured in snares modified for bear Creatinine kinase, lactate dehydrogenase, and amylase were
safety were higher than those for bears handled in their winter high in bears captured in snares, indicative of exertion
dens. However, injury scores did not differ either between the compared to reference values from ISIS and to values for
sexes or for juvenile bears compared to adults. Although young collar-darted bears. Warburton et a1. (1999) and Cattet et al.
bears struggled in snares more than adults, their small bodies (2003), respectively, noted elevated levels of these chemistries
and light weights apparently limited injuries due to struggling. for brush-tailed possums and grizzly bears captured in foot-1176 JOURNAL OF MAMMALOGY Vol. 86, No.6
restraining traps. What level of these parameters might indicate Field methods evolve by researchers dealing with conditions
excessive exertion? Wild black bears can be extremely active: unique to each field site and to each study. Pawlina and Proulx
they tear open logs, move large boulders, and climb trees. The (1999) recommended that traps and trapping methods be
effects of such exertion on blood profiles are unknown. The assessed only after an acclimatization period during which
blood chemistry profiles for collar-darted bears are represen- researchers become familiar with their methods.
tative of mildly active bears; they are not representative for Most important now is the need for researchers to evaluate
natural, strenuous activity. Before we can set criteria for their field methods with respect to objective criteria and to
physiological measures, we need physiological data for animals report the results. My coworkers and I worked hard over many
across the entire range of nonnal activities. Consequently, at years to minimize the impact of our trapping methods on the
present, no objective criteria exist to combine physiological bears we studied, yet I did not know before doing the analyses
measures with injury scores to evaluate whether traps are reported here that our methods would meet accepted standards.
humane. Similarly, no behavioral data exist to develop To accept hypothesis 1 was rewarding, yet analyses of field
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objective criteria for humane trapping. methods should be reported whether field methods meet
The blood chemistry levels reported here (Table 2) are accepted standards or not. Without such evaluations, we do
similar to those reported elsewhere for black bears (Eubanks not know how well our methods stand up to accepted, objective
et al. 1976; Hellgren et al. 1989; Matula et al. 1980) and other standards, we cannot improve the treatment of animals captured
bears (Cattet et al. 2003; Halloran and Pearson 1972), as is the for field research, we cannot reduce our impacts on their lives,
lack of difference of blood profiles for males and females and we chance having our methods bias our research results.
(Brannon 1985; Hellgren et al. 1989; Matula et al. 1980;
Schroeder 1987). Consistent with these other studies, I did find ACKNOWLEDGMENTS
that females had lower blood phosphorus levels, but not for the
Graduate students G. Warburton, J. Zimmerman, M. Homer, M.
reason often given: that lactating females have high P demand
Fritz, D. E. Seaman, J. Noel, A. Kovach, V. Sorensen, P. Mooreside,
(Brannon 1985). The lactating females I studied actually had T. Langer, M. Reynolds, J. Sevin, J. Favreau, and L. Brongo, and Visit-
higher P levels than did nonlactating adult females. The lack of ing Scientist F. AntoneIli collected data. More than 30 undergraduate
significant difference between profiles of lactating and non- interns, technicians, and volunteers also assisted in data collection, as
lactating females suggests that lactation does not place high did personnel from the North Carolina Wildlife Resources Commis-
physiological demands on bears in my study area. Given that sion, and more than 300 Earthwatch volunteers. M. Stoskopf, M.
lactation is energetically demanding in mammals (Kenagy et al. Mitchell, and 4 anonymous reviewers made suggestions that
1989, 1990; review by Moen 1973), bears in my study area significantly improved the manuscript. Financial and logistic support
appear to be in good condition with ample energy reserves and came from R. Bacon and K. Hailpern, the Bear Fund of the Wyoming
not subjected to food limitation. This suggestion is supported Chapter of The Wildlife Society, D. Brown, J. Busse, Citibank Corp.,
the Conservation Fund of the Columbus (Ohio) Zoo, the Geraldine R.
by data on food supplies and home ranges (Powell et a1. 1997).
Dodge Foundation, Earthwatchrrhe Center for Field Research, Federal
How foot snares are set is important (Mowat et al. 1994).
Aid in Wildlife Restoration Project W-57 administrated through the
Although we did not regularly note on data sheets whether North Carolina Wildlife Resources Commission, Grand Valley State
a snared bear had tangled its cable around logs, saplings, or University McNair Scholars Program, International Association for
shrubs, anecdotal evidence noted in field journals indicated that Bear Research and Management, G. & D. King, Mcintire Stennis
bears were more likely to be injured when hood springs could funds, the National Geographic Society, the National Park Service, the
not function well. Mowat et al. (1994) noted that tangled cables National Rifle Association, the North Carolina Agricultural Research
led to injuries for Canada lynxes (Lynx canadensis) trapped Service, North Carolina State University, 3M Co., the United States
with foot snares. Johnson and Pelton (1980), Huber et aL Department of Agriculture Forest Service, Wildlands Research
(1996), and Graf et aL (1992) noted that a foot snare must be Institute, Wil-Burt Corp., and Wildlink, Inc. Port Clyde and Stinson
Canning Companies donated sardines.
outfitted with something to cushion the strain when a bear
struggles at the end of its cable. My research does not suggest
carte blanc approval of foot snares for black bears but shows LITERATURE CiTED
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