Survival and Cause-Specific Mortality of River Otters in Southern Illinois

Rutter, Andrew U.; Hanrahan, Alex T.; Nielsen, Clayton K.; Schauber, Eric M.

doi:10.1674/0003-0031-180.1.160

Cited by 7 publications

(11 citation statements)

References 24 publications

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“…We provide insight and recommendations regarding Comstock traps as a live-capture method for river otters. Given a recent focus on river otter conservation, especially in the Midwest where populations have rebounded from historic lows during the 20th century (Nielsen 2016;Rutter et al 2018;Hanrahan et al 2019;Holland et al 2019), we believe that our findings are applicable to those considering alternative methods to live-capture river otters for research purposes.…”

Section: Discussionmentioning

confidence: 78%

“…We measured the functionality of a new design of box trap called a Comstock Custom Cage trap (Comstock Custom Cage LLC, Gansevoort, NY) (hereafter, ''Comstock trap'') to capture river otters for a radio telemetry study (Rutter et al 2018;Hanrahan et al 2019). Comstock traps differ from other cage-type live traps in that they include a suspended wire trigger mechanism rather than a traditional foot treadle and spring-powered doors.…”

Section: Introductionmentioning

confidence: 99%

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Functionality of a New Live-Capture Device for River Otters

Rutter

Hanrahan

Nielsen

et al. 2019

Journal of Fish and Wildlife Management

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Assessments of novel capture techniques are important to wildlife research. We used Comstock traps, a new live-capture technique, to capture North American river otters Lontra canadensis. We measured Comstock trap functionality in terms of river otter capture efficiency, furbearer capture efficiency, nonfurbearer capture efficiency, and malfunction rate. During 2014–2016, we captured 36 river otters (19 male, 17 female) in Comstock traps during 2,533 trap nights (1 capture/63 trap nights) at Crab Orchard National Wildlife Refuge in southern Illinois, USA. Eleven of 20 (55%) river otters assessed for capture-related injuries received an injury as a result of capture in a Comstock trap. The most common injury was claw loss (45%), followed by tooth fracture (25%) and lacerations (10%). The ease of setting Comstock traps and of releasing nontarget captures made them an appealing option for river otter live capture; however, two river otters died because of hypothermia, two died because of drowning, and one died because of traumatic injuries sustained during capture. Special care should be taken when selecting locations to set Comstock traps with regard to temperature and fluctuating water levels. Researchers attempting to live-capture river otters using this method would benefit by restricting their use to locations with predictable water levels and seasons with mild weather patterns.

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Section: Discussionmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Functionality of a New Live-Capture Device for River Otters

Rutter

Hanrahan

Nielsen

et al. 2019

Journal of Fish and Wildlife Management

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“…However, we noted several problematic issues that occurred, including contamination of equipment (solved by using backup supplies; we recommend having duplicates of every item that needs to be sterile), and a gust of wind that knocked the tent over during setup (solved by tying down the tent early during future setups when windy). Although intubation of animals under anesthesia is a standard procedure to reduce the risk of regurgitation, we felt the increased handling time and risk of injury from intubation outweighed the benefits, especially as a previous study performed surgeries on 35 river otters in our study area without intubating subjects and with no mortalities during surgery (Rutter et al 2018). Use of a pulse oximeter is also common for any type of chemical immobilization, but we struggled to obtain consistent readings from a paw (the tongue was covered by the mask), so we prioritized a faster processing time over obtaining blood oxygen saturation, which is also consistent with Rutter et al (2018).…”

Section: Discussionmentioning

confidence: 99%

“…Monthly temperatures during November–March 2018–2020 ranged from −17.8°C to 26.1°C and averaged 3.6°C (National Oceanic and Atmospheric Administration 2020). Further description of our study area can be found elsewhere (Rutter et al 2018, Hanrahan et al 2019, Rutter et al 2020).…”

Section: Study Areamentioning

confidence: 99%

River otter chemical immobilization and field surgery using nonscheduled drugs

Gettelman

Nielsen

Scimeca

et al. 2022

Wildlife Society Bulletin

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Radiotelemetry provides valuable information about wildlife populations that is often unattainable using other methods. Many vertebrate species can carry radiotransmitters on collarsor harnesses, but radiotelemetry can be more problematic for other species. River otters (Lontra canadensis) are typically radiomarked by surgically implanting intra-abdominal transmitters under general anesthesia. However, surgical requirements and restrictions on some immobilizing drugs may limit options for implanting river otters with radiotransmitters in the field.To address these issues, we developed a protocol for chemically immobilizing live-captured river otters with nonscheduled drugs (by estimated weight class; dexmedetomidine 0.06 mg/kg and nalbuphine 1.2 mg/kg) and conducting field surgeries at capture sites. We surgically implanted 23 river otters with radiotransmitters in southern Illinois during November 2018−March 2020. A plane of anesthesia suitable for surgery was maintained with isoflurane (1−4%). After surgery, capture drugs were reversed with atipamezole and river otters were typically released in 30−60 min. We recorded one surgery-related mortality and one post-surgery mortality.Our surgical method for radiomarking river otters minimized stress and handling time without compromising their health and demonstrated the efficacy of less-restricted chemical immobilization agents for river otters.

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“…Wisconsin has a large, stable river otter population but harvest tag availability is limited, and the season can be subject to early closure (Dhuey and Rossler 2018 b , Roberts 2018). River otters are captured incidental to beaver trapping because both species occupy similar habitats, are similar in size, and move through habitat in a similar manner (Swimley et al 1999, Kruuk 2006, Reid 2006, Bieber et al 2018, Rutter et al 2018). Consequently, most river otters harvested by licensed trappers (82%) and incidentally taken by USDA‐WS (85%) during beaver management activities in Wisconsin are caught in body‐grip traps (U.S. Department of Agriculture 2017, Dhuey and Rossler 2018 a ).…”

mentioning

confidence: 99%

An Evaluation of Body‐grip Trap Trigger Configurations for Reducing River Otter Take Incidental to Beaver Trapping

Sundelius

Forman

Roberts

et al. 2021

Wildlife Society Bulletin

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River otter (Lontra canadensis) populations in North America have been the focus of significant restoration efforts. Wildlife management agencies, concerned about the unintentional take of river otters incidental to beaver (Castor canadensis) trapping, may recommend techniques to avoid capturing river otters. River otter avoidance techniques that are ineffective or diminish trap performance for beavers are undesirable. We conducted a field evaluation in 2015 and 2016 in Wisconsin to assess how two trigger configurations (offset and center) on body‐grip traps would affect the incidental capture rate of river otters during beaver trapping. We also evaluated effects of each configuration on beaver capture rates, body lengths, and anatomical locations of trap‐jaw strikes. We used size 330 body‐grip traps equipped with identical triggers and alternated between trigger configurations during beaver damage management activities. We captured 8 river otters with each trap trigger configuration. Trap‐jaw strikes on beavers differed between trigger configurations, with offset triggers resulting in more abdomen strikes and center triggers causing more cervical vertebrae strikes. We found that an offset trigger configuration did not reduce incidental take of otters and was less effective for trapping beavers. © 2021 The Wildlife Society. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

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Survival and Cause-Specific Mortality of River Otters in Southern Illinois

Cited by 7 publications

References 24 publications

Functionality of a New Live-Capture Device for River Otters

Functionality of a New Live-Capture Device for River Otters

River otter chemical immobilization and field surgery using nonscheduled drugs

An Evaluation of Body‐grip Trap Trigger Configurations for Reducing River Otter Take Incidental to Beaver Trapping

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