Helicopter‐based immobilization of moose using butorphanol–azaperone–medetomidine

Abstract

Chemical immobilization is an important tool for the capture, study, and management of wildlife. Increased regulation of traditional opioids has necessitated a search for alternative drugs in wildlife capture. Butorphanol–azaperone–medetomidine (BAM) is one promising alternative that has been used in a range of taxa, though often on medium‐size mammals using ground‐based methods. We tested the efficacy of BAM via remote delivery from a helicopter in a wild population of moose (Alces alces shirasi) in northwestern Wyoming. In March 2020 and 2021, we immobilized male (n = 15) and female (n = 26) moose with butorphanol (0.20 mg/kg), azaperone (0.066 mg/kg), and medetomidine (0.079 mg/kg), with antagonists atipamezole (0.495–0.527 mg/kg) and naltrexone (0.124–0.151 mg/kg) to reverse immobilizations. Mean induction (x̄ ± SE; 9.2 ± 0.6 min) and mean recovery times (7.2 ± 0.5 min) were longer but still comparable to published instances of moose captured using traditional chemical immobilizers (carfentanil, etorphine, thiafentanil). All animals survived >60 days post‐capture. Our findings add to a body of work demonstrating that BAM provides rapid inductions, reliable sedation, and quick reversals in a variety of taxa and by aerial remote delivery. We assessed the efficacy of butorphanol–azaperone–medetomidine via remote delivery from a helicopter in a wild population of moose (Alces alces shirasi). Moose had brief inductions and recoveries, were unresponsive during handling, and had high rates of post‐capture survival. Butorphanol‐azaperone‐medetomidine is accessible to researchers and managers, has low toxicity to humans, and provided induction quality comparable to conventional immobilizers for a wild ungulate population.

Full text

Received: 10 May 2021
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Revised: 15 December 2021
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Accepted: 22 December 2021
DOI: 10.1002/wsb.1327
FROM THE FIELD
Helicopter‐based immobilization of moose using
butorphanol–azaperone–medetomidine
Rebecca L. Levine
1
|Samantha P. H. Dwinnell
2
|Bart Kroger
3
|
Corey Class
3
|Kevin L. Monteith
4
1
Haub School of Environment and Natural
Resources, University of Wyoming, 804 E
Fremont Street, Laramie, WY 82071, USA
2
Arctic and Terrestrial Biology, The University
Centre in Svalbard, P.O. Box 156 N−9187,
9170, Longyearbyen, Norway
3
Wyoming Game and Fish Department, 2820
WY‐120, Cody, WY 82414, USA
4
Haub School of Environment and Natural
Resources, Wyoming Cooperative Fish and
Wildlife Research Unit, Department of
Zoology and Physiology, University of
Wyoming, 804 E Fremont Street, Laramie,
WY 82071, USA
Correspondence
Rebecca L. Levine, University of Wyoming,
804 E Fremont Street, Laramie, WY 82071.
Email: rlevine1@uwyo.edu
Funding information
Wyoming Game & Fish Department;
A. Young and J. Nielson; M. Newhouse;
Wyoming Governor's Big Game License
Coalition; M. and C. Rumsey
Abstract
Chemical immobilization is an important tool for the capture,
study, and management of wildlife. Increased regulation of
traditional opioids has necessitated a search for alternative
drugs in wildlife capture. Butorphanol–azaperone–medetomidine
(BAM) is one promising alternative that has been used in a range
of taxa, though often on medium‐size mammals using ground‐
based methods. We tested the efficacy of BAM via remote
delivery from a helicopter in a wild population of moose (Alces
alces shirasi) in northwestern Wyoming. In March 2020 and 2021,
we immobilized male (n= 15) and female (n= 26) moose
with butorphanol (0.20 mg/kg), azaperone (0.066 mg/kg), and
medetomidine (0.079 mg/kg), with antagonists atipamezole
(0.495–0.527 mg/kg) and naltrexone (0.124–0.151 mg/kg) to
reverse immobilizations. Mean induction (x±SE; 9.2±0.6min)
and mean recovery times (7.2 ± 0.5 min) were longer but still
comparable to published instances of moose captured using
traditional chemical immobilizers (carfentanil, etorphine, thiafen-
tanil). All animals survived >60 days post‐capture. Our findings
add to a body of work demonstrating that BAM provides rapid
inductions, reliable sedation, and quick reversals in a variety of
taxa and by aerial remote delivery.
KEYWORDS
aerial capture, Alces, azaperone, BAM, butorphanol, helicopter,
immobilization, medetomidine, moose
Wildlife Society Bulletin 2022;46:e1327. wileyonlinelibrary.com/journal/wsb
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© 2022 The Authors. Wildlife Society Bulletin published by Wiley Periodicals LLC on behalf of The Wildlife Society.

Capture yields valuable information for the management and conservation of wildlife populations (Clutton‐Brock
and Sheldon 2010, Monteith et al. 2014). Large‐bodied mammals introduce a variety of challenges to capture
because animals can be susceptible to musculoskeletal injury and aggressive towards humans. Thus, helicopters are
used commonly for the remote delivery of chemical immobilizers. Potent opioids, including carfentanil, etorphine,
and others have been used to immobilize wild mammals since the 1970s and 1980s (Woolf et al. 1973, Franzmann
et al. 1984). More recently, thiafentanil largely replaced other opioids as it provides similar induction quality with a
lower therapeutic index and faster induction time (Kreeger et al. 2005, Lian et al. 2016). Although the induction
qualities, physiological effects, and reversal methods of conventional drugs are well documented (Delvaux et al.
1999, Roffe et al. 2001, Evans et al. 2012), many are no longer available for wildlife capture. Rising opioid abuse
worldwide resulted in heightened regulation of narcotics (Jones et al. 2019); etorphine hydrochloride, carfentanil,
and thiafentanil are all restricted as U.S. Drug Enforcement Agency schedule II opioids with a manufacturing
cessation further impacting carfentanil availability (Drug Enforcement Administration 2016,2020). The
identification of more accessible immobilizers with comparable effectiveness and safety is therefore timely and
critical.
The drug combination butorphanol–azaperone–medetomidine (BAM) has grown in popularity for wildlife
capture (Wolfe et al. 2014,Semjonovetal.2018). Butorphanol is a synthetic opioid with sedative and pain‐
relieving properties, azaperone is a tranquilizer that depresses the nervous system, and medetomidine is a
pain‐relieving sedative (MacDonald et al. 1988, Kreeger and Arnemo 2012). Together, BAM is a reversible
drug combination with low toxicity to humans that has been used successfully for immobilization in many
taxa (e.g., elk [Cervus canadensis nelsoni,Wolfeetal.2014]; beaver [Castor canadensis,Rougetal.2018];
cheetah [Acinonyx jubatus,Semjonovetal.2018]; black bear [Ursus americanus, Williamson et al. 2018]). Most
published BAM immobilizations have used ground‐based methods on medium‐sized mammals, thus, the
efficacy of remote delivery via helicopter to capture megafauna is largely undetermined (Harms et al. 2018,
McDermottetal.2020). Yet, BAM is uniquely promising for remote delivery systems because medetomidine
potentiates butorphanol, thereby reducing injection volume and allowing for improved accuracy with lighter
darts (Jalanka and Roeken 1990).
We evaluated the effectiveness of remote delivery of BAM from a helicopter in a wild population of adult
Shiras moose (Alces alces shirasi). During a study on moose ecology, we located and darted adult male and female
moose via helicopter with BAM premix (butorphanol 27.3 mg/ml, azaperone 9.1 mg/ml, and medetomidine
10.9 mg/ml). We subsequently reversed inductions with atipamezole and naltrexone. We tested how BAM
compared with traditional immobilizers for the helicopter‐based capture of wild ungulates. To evaluate BAM, we
focused on sedation quality, capture efficiency, and animal welfare. First, we assessed sedation quality by response
to stimuli and duration of immobilization. Second, we measured capture efficiency by timing of induction and
recovery. Third, we assessed animal welfare by checking vitals (rectal temperature, pulse, and oxygen saturation),
quantifying recovery times, and monitoring for post‐capture mortality. We further compared the responses of
males and females to the drug by dose per kilogram of body mass. Finally, to assess whether BAM is a viable
alternative for the capture of large mammals, we compared our findings to previously published moose
immobilizations with etorphine, carfentanil, xylazine, succinylcholine, thiafentanil, and their permutations.
STUDY AREA
We conducted our work in the Absaroka Mountains, Wyoming, USA, (44°1′27.84″N, 109°10′18.48″W) during
March 2020 and 2021. The climate was temperate and semi‐arid with average annual precipitation of 43cm (PRISM
Climate Group, https://www.prism.oregonstate.edu/). March had a mean low temperature of −9°C and mean high
temperature of 6°C. Ambient temperatures during capture were −8–4°C. Elevation of captures ranged from 1,900
to 3,000 meters above sea level. Snow accumulation in capture areas was <0.5 meters. The region had coniferous
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forests at high elevations, open shrubby habitat at low elevations, deciduous riparian areas, and agricultural land.
High elevation conifer species included subalpine fir (Abies lasiocarpa), Englemann's spruce (Picea engelmannii),
whitebark pine (Pinus albicaulis), and limber pine (Pinus flexilis). Lowlands were dominated by big sagebrush
(Artemisia tridentata), Rocky Mountain juniper (Juniperus scopulorum), and mixed grasslands. Riparian areas were
comprised of cottonwoods (Populus angustifolia, P. trichocarpa) and willows (Salix spp.). Agricultural land use was
predominantly hay cultivation (Medicago sativa).
METHODS
We located 41 adult moose (26 females and 15 males) via helicopter and darted them with a cartridge‐fired
projector (Model 196, Pneu‐Dart, Williamsport, PA, USA). Chase times were routinely <2 minutes, and never
exceeded 5 minutes. Darts contained a premix of butorphanol (27.3 mg/ml; ZooPharm, Laramie, WY, USA),
azaperone (9.1 mg/ml; ZooPharm), and medetomidine (10.9 mg/ml; ZooPharm). We loaded darts for females with
2.2 ml and darts for males with 2.4 ml of BAM premix. We monitored moose responses to the initial dose and
darted the moose again with a full dose if there was no response to the drug within 15minutes. Capture crews
recorded the time darted and time of recumbency.
Uponarrivaltotheimmobilizedmoose,weadjustedheadposturetoaidrespirationandpreventaspiration
(Arnemo et al. 2003), although moose routinely remained in sternal recumbency, with head positioned
horizontally against the body. We removed the dart, and administered an anti‐inflammatory, flunixin
megalumine, intravenously (8.0 ml for males, 6.0 ml for females; 50 mg/ml; VetOne, Boise, ID, USA), and
prophylactically administered an antimicrobial, tulathromycin, subcutaneously (9.0 ml for males, 7.0 ml for
females; 100 mg/ml; Zoetis, Parsippany, NJ, USA). We measured pulse and oxygen saturation (SpO
2
)usinga
pulse oximeter (Ohmeda TuffSat, General Electric Healthcare,Chicago,IL,USA);ininstanceswhereoxygen
saturation was seemingly low, we continued to monitor thereafter (Kreeger and Arnemo 2012). In the event of
consistently low oxygen saturation (<70%) or a downward trend in readings, we were prepared to supply
supplemental oxygen or reverse the immobilization. We took rectal temperature (Vicks SpeedRead Digital
Thermometer, Procter & Gamble, Cincinnati, OH, USA) andusedanupperlimitof40.5°Cforthecontinuation
of processing. As part of a different research objective, we also collected morphometric measurements,
counted tick abundance, extracted an incisiform canine (for those captured for the first time), drew blood, and
collected hair and fecal samples. We assessed nutritional condition via palpation and ultrasonography of fat
depth (Stephenson et al. 1998,Monteithetal.2014). We checked pregnancy status via transrectal
ultrasonography (Stephenson et al. 1995), fitted pregnant females with vaginal implant transmitters, and
deployed GPS collars on all moose (VERTEX PLUS Collar; Vectronic Aerospace GmBH, Berlin, Germany).
We administered antagonists upon completion of handling procedures. Antagonists, atipamezole
(25 mg/ml; ZooPharm) and naltrexone (50 mg/ml; ZooPharm), were administered intramuscularly using
2 separate syringes. For females, we used target doses of 6.0 ml atipamezole (0.02/kg body mass) and 0.75 ml
naltrexone (0.002/kg body mass). In males target doses were 7.0 ml atipamezole (0.02/kg body mass) and
1.0 ml naltrexone (0.003/kg body mass). We recorded the start time of handling, time of antagonist injection,
andtimethemoosewasfirststanding.
We used the recorded times to calculate the following variables: induction time (darting to recumbency),
approach time (recumbency to approached), handling time (approached to reversed), recumbent time (start of
recumbency to standing), and recovery time (antagonist dose to standing). We used Welch's 2 Sample t‐test to
compare event times and first vitals between males and females. We calculated body mass using body length and
chest girth (body mass = 87.8 + 30.0 × body length × chest girth
2
; Hundertmark and Schwartz 1998), and
subsequently tested relationships between event times (induction and recovery) and drug dose per kilogram of
body mass with the Pearson correlation coefficient. We performed all analyses with R (v. 4.0.3; R Core Team 2020).
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RESULTS
A single dart was sufficient to immobilize 37 of 41 moose. The 4 moose that required an additional dose of BAM
were darted with a full second dart after 15 minutes. One female was initially darted in the abdomen and showed
partial response. The second dart was administered from the ground and, though induction time after the second
dart was <10 minutes, the exact start of recumbency was not observed. One male and a second female showed no
response because the initial darts had frozen, rendering the agonist inert. Lastly, in a male showing no response to
the initial dose, the first dart partially penetrated the tuber ischium and consequently, none or very little of the
agonist was received by the animal as evidenced by the full dart upon removal. All moose that required a second
dart either had shot placement that prevented absorption of BAM into the bloodstream or inert agonist. We
censored the 4 moose who required additional darting from our analyses because they were not representative of
standardized capture conditions. Upon recumbency, no additional doses were necessary. Mean induction time was
9.2 ± 0.6 minutes (n= 36) and induction times did not differ between males and females (Table 1). Induction time did
not vary with BAM dose per kilogram of body mass (Pearson's r=−0.277, P= 0.102).
Upon approach, all moose were in sternal or lateral recumbency with head lowered. Approach time was
25.4 ± 1.6 minutes (n= 28) and did not differ between males and females (Table 1). We noted persistent salivation
and sporadic respiratory vibrations (i.e., snoring) during immobilizations. We did not observe muscle twitching or
responses to stimuli. Temperature, pulse, and oxygen saturation also did not differ between males and females
(Table 1). Mean rectal temperature was 38.0 ± 0.2°C (n= 36). Mean pulse was 113.0 ± 8.4 beats per minute (n= 31;
slightly reduced sample size because of technological malfunction and failed reading of heart rate). Mean oxygen
saturation was 84.7 ± 1.3% (n= 36). In instances where oxygen saturation was initially low (<70%), we did not
observe downward trends and in no instances did saturation remain low. No supplemental oxygen was
administered. Mean body mass estimated via morphometric equations was 330 ± 7.9 kg and did not differ between
sexes (t
21
= 0.466, P= 0.646, n= 37). Ingesta‐free body fat was greater for females (6.53 ± 0.27%, n= 24) than for
males (5.24 ± 0.23%, t
34
= 3.651, P< 0.001, n= 13).
Mean recovery time was 7.2 ± 0.5 minutes (n= 37). Recovery time did not differ between sexes (Table 1).
Recovery time did not vary depending on dose of BAM, atipamezole, or naltrexone per kilogram of total body mass
(Pearson's r= 0.019, P= 0.913; r=−0.001, P= 0.995; r=−0.002, P= 0.990, respectively). Upon recovery,
TABLE 1 Welch's 2 Sample t‐test comparison of event times and vitals for male and female moose (Alces alces
shirasi) immobilized with butorphanol‐azaperone‐medetomidine during helicopter‐based captures in March
2020–2021, Wyoming, USA. Event times include induction (darting to recumbency), approach (recumbency to
approached), handling (approached to reversed), recumbent (start of recumbency to standing), and recovery
(antagonist administration to standing).
Females Males Tests
Mean Range nMean Range nt P df
Induction (min) 9.4 5–19 23 8.6 6–18 13 0.751 0.459 27.32
Handling (min) 25.3 20–32 24 20.6 13–28 13 3.027 0.007 19.85
Approach (min) 25.7 11–52 18 25.0 18–36 10 0.214 0.833 24.46
Recumbent (min) 51.1 36–83 18 45.2 36–54 10 1.844 0.077 25.75
Recovery (min) 6.7 3–13 24 8.3 5–18 13 −1.633 0.117 21.08
Temperature (°C) 38.0 35.2–40.5 23 38.0 36.4–39.8 13 −0.174 0.863 31.05
Heart rate (bpm) 114.4 40–240 21 109.9 62–175 10 0.289 0.774 26.35
SpO
2
(%) 84.4 62–100 23 85.2 67–98 13 −0.268 0.791 22.17
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we observed 5 moose coughing for up to one minute. Moose were recumbent for an average of 49.0 ± 1.8 minutes
(n= 28). Time to recumbency did not differ between sexes. Handling time was longer for females than males
(Table 1), likely because of additional time for pregnancy assessment. There were no mortalities during capture, nor
in the 2 months following capture.
DISCUSSION
A viable alternative to traditional immobilizers must provide timely inductions and reversals, induce reliable
sedation, and require a small injection volume that is compatible with remote delivery systems. Our results indicate
that BAM provided induction and recovery times that were longer but comparable to traditional drugs used for
moose immobilization (Table 2). Our immobilizations with BAM induced complete and consistent loss of
consciousness; moose remained unresponsive to stimulus until antagonists were administered. As for injection
volume, BAM doses fell within the range of volumes for traditional immobilizers (Table 2). The absence of significant
relationships between dose per kilogram of body mass and induction or recovery times suggests a buffered margin
for safe, effective dosing with BAM and its antagonists. Thus, BAM is a viable immobilant for aerial capture in terms
of induction quality, timing, and remote delivery.
TABLE 2 Comparison of chemical immobilants in moose (Alces alces) by mean dose per kilogram body mass,
event times, and mortalities
a
. Values for butorphanol‐azaperone‐medetomidine were from the present study,
March 2020–2021, Wyoming, USA
b
. Doses and timing for other drugs are from published accounts of capture.
Agonist
Dose
(mg/kg)
Volume
(ml)
Induction
(min) Antagonist
Dose
(mg/kg)
Recovery
(min) Mortalities nSource
Butorphanol‐
azaperone‐
medetomidine
0.197–0.198 2.2–2.4 9.2 ± 0.6 Atipamezole
naltrexone
0.495–0.527 7.2 ± 0.5 0 37 Present study
0.066 0.124–0.151
0.079
Butorphanol‐
azaperone‐
medetomidine
0.26 ± 0.08 3–4 8.3 ± 2.6 Atipamezole
naltrexone
~0.55 6.7 ± 3.8 0 53 Lamglait et al.
2021
0.09 ± 0.03 ~0.78
0.11 ± 0.03
Thiafentanil 0.030–0.033 1 2.4 ± 0.4
3.6 ± 0.2
Naltrexone 0.90–0.99 2.9 ± 0.2 3 73 Kreeger et al.
2005
Succinylcholine 0.051 0.95–1.90 13.0 ± 0.4 ———18 252 Delvaux et al.
1999
Xylazine 4.0 4.3–5.0 8.7 ± 1.5 RX821002A 0.58 2.8 1 40 Delvaux et al.
1999
Carfentanil‐
xylazine
0.007 1.17–1.50 6.6 ± 0.4 Naltrexone 0.709 3.7 4 72 Delvaux et al.
1999
0.181
Etorphine 0.192–0.260 0.77 4.4 ± 2.6 Diprenorphine ——0 19 Haga et al.
2009
Etorphine‐xylazine‐
acepromazine
0.010 3.75 6.5 ± 2.5 Diprenorphine
atipamezole
0.013 2.2 ± 0.5 0 15 Evans et al.
2012
0.221 0.022
0.440
a
Post‐capture mortality monitoring was not standard, with some publications lacking mention of the time window. Known
mortality monitoring ranged from several days to 12 weeks.
b
Doses (mg/kg) for present study and Kreeger et al. 2005 calculated with mean body mass for Shiras moose (Schladweiler
and Stevens 1973).
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Like many immobilizers, BAM has cardiovascular side effects. Butorphanol can reduce respiration via nervous
system depression, azaperone has caused tachycardia and hypotension in domestic ungulates, and medetomidine
can prompt vasoconstriction and bradycardia (Serrano and Lees 1976, Sinclair 2003, Malamed 2017). Although
some of the side effects may counteract each other (i.e., tachycardia and bradycardia, hypotension and
vasoconstriction), the use of BAM is not without risk, including mainly respiratory depression and aspiration
(Arnemo et al. 2003, Mich et al. 2008, Siegal‐Willott et al. 2009). We observed a wide range of oxygen saturation
levels (62–100%) with one animal dropping below 70%. Yet, recovery times were predictable (3–18 minutes), and
all moose survived more than 60 days post‐capture with no obvious detrimental effects. Variable oxygen saturation
may point to the inconsistency of pulse oximetry, possibly because of vasoconstriction from medetomidine (Talke
and Stapelfeldt 2006, Malinowski et al. 2019). Given technological shortcomings, trends in oxygen saturation are
regarded as more informative than absolute SpO
2
values (Kreeger and Arnemo 2012). Moose with low initial
oxygen saturation all showed subsequent upward trends after adjustment of head position.
General wildlife handling protocols recommend corrective action in the event of sustained (>2 minutes) low
oxygen saturation (<70%; Kreeger and Arnemo 2012). A respiratory stimulant, doxapram hydrochloride, can be
used with supplemental oxygen to treat respiratory depression (Thompson et al. 2020) or in combination with chest
compressions to treat respiratory arrest (Arnemo et al. 2003). Appropriate interventions to treat low oxygen
saturation can protect against organ damage, capture myopathy (Kreeger and Arnemo 2012), and post‐capture
hyperthermia (Thompson et al. 2020). Nevertheless, respiratory depression in sedated moose remains under-
studied, and currently no standard lower threshold for oxygen saturation exists for this cervid (Arnemo et al. 2003).
Such limitations on species‐specific protocols highlight the importance of supplemental oxygen availability and fast
acting antagonists for precautionary reversal of immobilization.
Aspiration of saliva or regurgitated rumen fluid is a known risk during moose capture and is exacerbated by
chemical immobilization (Arnemo et al. 2003). Our protocols mitigated aspiration risk and facilitated saliva drainage
by positioning moose in sternal recumbency and supporting the head with nose below the neck or positioning the
head horizontally against the body (Arnemo et al. 2003). Such precautions, however, were only possible after the
arrival of capture crews. We noted coughing after recovery in a few instances, though, we suspected the coughing
to be associated with excessive salivation with BAM as opposed to aspiration of rumen fluid (Ellis et al. 2019).
Although we observed respiratory side effects (audible respiration, coughing upon recovery, and variable
oxygen saturation), survival post‐capture was unaffected. Outcomes of eastern moose (Alces acles americanus)
captured with BAM reflected our findings (Lamglait et al. 2021). Similar capture protocols with a different
subspecies yielded moderate induction and reversal times, reliable immobilization, and only low oxygen saturation
as the primary animal welfare concern (Lamglait et al. 2021). Agonist and antagonist dosing varied between studies;
our captures used lower drug volumes and doses per kilogram body weight of BAM and naltrexone yet produced
similar induction, sedation quality, and reversal (Table 2). Accordingly, we conclude that BAM is a promising tool for
the aerial immobilization of moose and suggest follow‐up studies to further investigate blood oxygen levels, validate
our results, and test the efficacy of BAM in other species.
MANAGEMENT IMPLICATIONS
Moose immobilized with BAM had brief inductions and recoveries, were unresponsive during handling, and had
high rates of post‐capture survival. Furthermore, injection volume, induction time, and recovery time were
compatible with aerial capture needs (light darts for remote delivery and efficient use of flight time). As with all
capture efforts, dosages were specific to capture technique and animal size. We suspect associated dosage would
be less for ground capture when animals are less aroused (Kreeger et al. 2005, Thompson et al. 2020). Larger moose
subspecies also may require greater drug volume (Lamglait et al. 2021). Based on variability in oxygen saturation
levels, we recommend that supplemental oxygen be available when using BAM. The mean cost of inducing and
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antagonizing one moose with BAM, atipamezole, and naltrexone was $45–55. Inducing and reversing moose with
BAM was roughly 500% less expensive than costs reported for opioids used in the 1980s and 1990s (Delvaux et al.
1999). Helicopter flight time is expensive and poses high risk to personnel; thus, rapid and reliable inductions and
reversals, like those found with BAM, are essential to efficient use of resources and mitigation of flying risk. Though
BAM was efficacious for the capture of free‐ranging moose, in many instances, a potent and commercially available
opioid like thiafentanil is preferable for shorter inductions and reversals, smaller drug volumes, and upright head
position (Kreeger et al. 2005, Lian et al. 2016). Nevertheless, on the shifting landscape of opioid regulation,
manufacturing, and availability, BAM is accessible to researchers and managers, has low toxicity to humans, and
provided induction quality comparable to traditional immobilizers for a wild ungulate population.
ACKNOWLEDGMENTS
We thank A. Pils with the Shoshone National Forest, and the Wyoming State Veterinary Lab. A special thank you to
our pilots: K. Stenberg with Yarak Aviation, D. Rivers with Native Range Capture Services, and T. Herby with 307
Aviation. We acknowledge C. Kroger for her continued support of capture efforts. This work was made possible by
the gracious permission of many private landowners in the Meeteetse region. A special thank you to S. Brainerd
(Associate Editor), A. Knipps (Editorial Assistant), A. Tunstall (Copy Editor), J. Levengood (Content Editor), and 2
anonymous reviewers for their careful consideration and feedback on the manuscript. Our work was supported by
the Wyoming Game and Fish Department, M. and C. Rumsey, M. Newhouse, A. Young and J. Nielson, and the
Wyoming Governor's Big Game License Coalition.
CONFLICTS OF INTEREST
The authors declare no conflicts of interest.
ETHICS STATEMENT
All capture and handling protocols were approved by the Wyoming Game and Fish Department (Chapter 33–1285)
and the University of Wyoming Institutional Animal Care and Use Committee (protocol 20200305KM00412‐01).
ORCID
Rebecca L. Levine http://orcid.org/0000-0002-3913-2911
Kevin L. Monteith http://orcid.org/0000-0003-4834-5465
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Associate Editor: S. Brainerd.
How to cite this article: Levine, R. L., S. P. H. Dwinnell, B. Kroger, C. Class, and K. L. Monteith. 2022.
Helicopter‐based immobilization of moose using butorphanol–azaperone–medetomidine. Wildlife Society
Bulletin 46:e1327. https://doi.org/10.1002/wsb.1327
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23285540, 2022, 3, Downloaded from https://wildlife.onlinelibrary.wiley.com/doi/10.1002/wsb.1327 by Rebecca Levine - Wyoming State Library , Wiley Online Library on [19/09/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License