NINA Minirapport 203. Refinement of research capture techniques for Eurasian lynx in Norway ( )

Transcription

1 Refinement of research capture techniques for Eurasian lynx in Norway ( ) John Odden John D. C. Linnell Jon M. Arnemo Finn Berntsen

2 Odden, J., Linnell, J.D.C., Arnemo, J. M. & Berntsen, F Refinement of research capture techniques capture of Eurasian lynx in Norway NINA Minirapport 203. Trondheim, september 2007 RETTIGHETSHAVER Norsk institutt for naturforskning TILGJENGELIGHET Upublisert PUBLISERINGSTYPE Digitalt dokument (pdf) ANSVARLIG SIGNATUR John D.C. Linnell (sign.) OPPDRAGSGIVER(E) Direktoratet for naturforvaltning, Forsøksdyrutvalget KONTAKTPERSON(ER) HOS OPPDRAGSGIVER Morten Kjørstad (DN) NØKKELORD Gaupe, Lynx lynx, Norge, fangstmetoder KEY WORDS Eurasian lynx, Lynx lynx, capture techniques, Norway, FOTO NINA Minirapport er en enklere tilbakemelding til oppdragsgiver enn det som dekkes av NINAs øvrige publikasjonsserier. Minirapporter kan være notater, foreløpige meldinger og del- eller sluttresultater. Minirapportene registreres i NINAs publikasjonsdatabase, med internt serienummer. Minirapportene er ikke søkbare i de vanlige litteraturbasene, og følgelig ikke tilgjengelig på vanlig måte. Således kan ikke disse uten videre refereres til som vitenskapelige rapporter. KONTAKTOPPLYSNINGER NINA hovedkontor 7485 Trondheim Telefon: Telefaks: NINA Oslo Gaustadalléen Oslo Telefon: Telefaks: NINA Tromsø Polarmiljøsenteret 9296 Tromsø Telefon: Telefaks: NINA Lillehammer Fakkelgården 2624 Lillehammer Telefon: Telefaks:

3 Preface The National Animal Research Authority (Forsøksdyrutvalget) in a letter dated 30 th March 2007 (ref S-2007 / 7883) requested that we provide a review of the capture methods used by the lynx project in Norway, with special emphasis on the ways in which our methods have been refined during the projects life time. This document is intended to fulfill this requirement. Trondheim, September 2007 John D. C. Linnell 3

4 Introduction The modern era of lynx research in Scandinavia started in the mid 1990s, with 4 large scale radiomarking projects started in Norway and Sweden. The projects are now organized under a common umbrella, referred to as Scandlynx ( Linnell et al. 2005). In the mid 1990s lynx had recolonized most parts of Scandinavia, but management of the species was based on a near total absence of scientific information concerning the species ecology. However, 13 years of intensive lynx research in several parts of Scandinavia have provided a wealth of information about the ecology of this species (Andersen et al. 2005). We can now provide decision makers (politicians and wildlife managers) with a great deal of detailed and robust data about many aspects of lynx ecology. We know how large areas each animal needs, how many roe deer they kill, how many kittens they produce, how well they survive, what they die of, how many lynx there are in a population etc. This information is vital when making management decisions, and when conservation plans are being made that will secure their future in Scandinavia, and ensure that management is sustainable. It is fair to say that 99% of this knowledge has been gained through the use of radio-transmitters and could not have been gained in any other way. Radio-collaring implies live-capturing an animal, immobilising it, and releasing it with a radio around its neck. All these procedures impose a certain stress on the animal and have an associated risk, because, despite the most elaborate planning, and the use of state of the art equipment and drugs, things occasionally do go wrong and unfortunate accidents happen. It is clearly our goal to minimise these events for a number of reasons. Firstly, as scientists, the data that we collect from an animal is useless to us if our marking influences their behaviour or lives in any way. Secondly, as both professionals and individuals we recognise the welfare and ethical issues associated with research and do not want to induce unnecessary risk and suffering to animals. Therefore, we are very careful to analyse the impact of our actions on the animals that we study. In this report we evaluate the mortality risks associated with research capture of lynx using different methods during the last 13 years of activity in Norway and outline how we have learnt from our experience to minimise the chances of the same circumstances repeating themselves. Refining lynx capture techniques Capture mortality Since 1995, 140 individual lynx have been captured and equipped with radio-transmitters and/or microchips/tattoos in Hedmark, Akershus, Østfold, Buskerud, Telemark, Troms and Finnmark counties. We have captured adult lynx and juveniles (> 5 months) using walk through box-traps, springloaded foot-snares and trained dogs. We have also immobilized lynx on foot and from cars and helicopters. Finally, neonatal kittens were captured by hand at natal lairs. In Norway, 5 capture related deaths (2.9%) occurred during 175 capture events since 1995 (Table 1). Due to refining of our capture methods and the increasingly experienced personnel, the overall capture mortality rate has dropped from 3.7% (107 captures) during 1995 to 2002 to 1.4% (70 captures) during Box traps No lynx has ever died or been seriously injured in a wooden or metal mesh walk through box-trap (44 captures). In the initial years we used box-traps made of metal mesh following a design widely used in central Europe for lynx research. However, to reduce the minor damage that we occasionally observed on claws, we changed our methods to only use boxes constructed of solid wood or with wood covering on the inside. This has reduced the problem with claw injuries to a minimum. Since the start in 1995 all box-traps have been checked using electronic radio-alarms (VHF) or sms-alarm on the box traps to determine when captures occur. As technology develops we antici- 4

5 pate going over to a more regular use of sms alarms that will allow our response time to become slightly faster. Table 1 Capture mortality using different techniques in Norway See text for explanations of the different methods. Methods N Number of deaths Capture 1 Anaesthetic 2 Snares old type Snares modified type Box traps Dogs Immobilized from a helicopter Immobilized from a car Immobilized on foot (stalking) Kittens at den radio-marked Kittens at den tattoo Deaths directly associated with capture technique involved mainly due to physical injury. 2 Deaths due to physiological reactions, mainly from adverse effects of drugs, not associated with injury from capture technique 3 This includes only kittens captured at natal dens where we know the fate of the kitten after capture. Snares We have captured lynx 48 times with spring-loaded foot-snares placed at lynx-killed prey. Two animals (one yearling female and adult male) were euthanized due to leg fractures, and as a consequence the snares and snaring procedure were changed in several ways. First, snares are covered with a plastic sleeve to reduce the possibility of teeth injures. The snares are now fixed to trees both at the end and at the front to reduce the mobility radius of the captured animal, and consequently the possibilities for leg fracture. We also now routinely cut down small trees or move the kill away from trees to reduce possibilities for leg fracture. The snares have always been continually monitored using radio-alarms. However, we have reduced our reaction time upon capture to less than 20 minutes. We do not capture if the roe deer kills are far from roads. No injures have been recorded after these changes were made. Following observation of some corrosion inside the spring tubes, we have overhauled all our snares, replacing parts with stronger components and adding a safety feature to ensure that the animal will remain snared even if the spring should break. Capture by darting (car, helicopter, stalking) We immobilized 13 lynx by darting on foot, or from car and helicopter. We have had no deaths from dart misplacement. However, 2 animals died from drug related effects see below. Darting from helicopter and cars is difficult, therefore, we only use a skilled and experienced capture team to reduce the risk of mortality to a minimum. To avoid stress and physiological side effects (hyperthermia) during immobilization, we avoid intensive chasing and the total time of pursuit does not exceed 30 minutes. Dogs When pursued by dogs, lynx will readily climb trees, thus enabling their capture by darting. We have used dogs to recapture lynx and to capture > 5 months old kittens of radio-collared females. The dogs were released as close to the radio-located lynx as possible, and the lynx were chased until they escaped, climbed a tree, or sought refuge under rocks. Once a lynx was in a tree, they were darted and caught in a net if they fell. We had no accidents with trained dogs (15 captures). Based on Swedish experience, we make sure the total time of pursuit does not exceed 30 minutes to avoid stress and physiological side effects (hyperthermia) during immobilization. 5

6 Capture at natal lair Neonatal kittens have been captured by hand at natal lairs and instrumented with free-floating intraperitoneal implant transmitters (Arnemo et al. 1998, 1999, 2006). We have subsequently stopped using implants. However, all kittens of radio-collared females get an ear tattoo and microchip when we visit the lair when the kittens are 3-5 weeks of age. We have had no accidents due to implanting in Norway. However, in 2002 a 5 week old kitten was killed by a dog. The accident happened when a female lynx overnight moved the kitten 2 km from its lair without us knowing. We went in expecting to find a kill with a dog on a leash when the dog bit the kitten lying unprotected under a tree. We have never seen this behaviour from a female lynx before or after. Refining the chemical immobilisation 123 captures have involved chemical immobilisation of lynx, and 2 deaths were due to effects of the chemical immobilizing. In 1996 a male lynx died from possible hyperthermia after being immobilized with medetomidine ketamine, and reversed by atipamezole. After this we changed the doses of both medetomidine and atipamezole. In addition, we are now consequent about giving the antidote (atipamezole) through intra-muscular, rather than intra-venous, injection. In 2007 a 13.5 year old (this is very old for a lynx) female died after being immobilized from helicopter in Troms. The autopsy, which was carried out at the National Veterinary Institute, showed a tumour which may have contributed to her poor body condition and subsequent death. Chemical immobilization or anaesthesia of free-ranging mammals is a form of veterinary anaesthesia conducted under the most difficult circumstances, and the risk of severe side effects, injuries and death can never be eliminated. The health of a free-ranging animal can seldom be assessed prior to capture, and the presence of any pathologic condition will significantly increase the risk of mortality. However, there is no doubt that the anaesthetic risk in wild animals is highly influenced by the capture protocol that is being applied. Therefore, we use the official biomedical and anaesthetic protocol developed during the past years in Scandinavia (Arnemo og Fahlman 2007). Discussion This short summary demonstrates that no live animal capture techniques are without risk, however, we have also demonstrated that by refining our capture methods the percentage of animals being killed has dropped dramatically. Each accident has been investigated, and where possible we have taken steps to prevent the same mistake from happening again. What does the future hold? There has been a rapid development in recent years of new noninvasive techniques such as DNA sampling from hair, faeces and urine and camera-trapping. Hopefully the future development and application of these methods will minimise the need to use handson, capture-based methods. However, there are many questions that cannot be answered in any other way except through the application of telemetry methods, which will require capturing animals. As we gain experience and develop techniques we will continue to minimise the things that can go wrong, but no routine will ever be perfect. Advances in telemetry equipment, such as the development of GPS collars and drop-off mechanisms, will reduce the need to recapture animals to remove collars following short-term intensive studies (e.g. predation studies). However, some questions (such as those focusing on demographics) are best answered by following a small sample of individuals over many years. Again, the development of new batteries and duty-cycle based collars will reduce the required frequency of recapture. In summary, the current lynx management system that parliament have decided upon requires very detailed data about most aspects of lynx ecology. This will require that wildlife management agen- 6

7 cies continue to commission lynx research from the various wildlife research institutions. If research groups are to provide the data and ecological knowledge which management agencies require there is likely to be an ongoing need for the application of telemetry techniques, and the subsequent need for animal capture. This report provides a short insight into our ongoing work to minimise the associated mortality risks. Mortality is however only the most extreme and serious consequence. Our next steps will to examine in greater detail how capture events influence lynx reproduction and space use which may reflect more subtle effects of capture. Literature The literature and a detailed description of our capture techniques can be can be downloaded from our web page (right click, save as ) Andersen, R., Odden, J., Linnell, J. D. C., Odden, M., Herfindal, I., Panzacchi, M., Høgseth, Ø., Gangås, L., Brøseth, H. & Solberg, E. J Lynx and roe deer in south eastern Norway: activity [in Norwegian with English abstract]. NINA Rapport 29: 44pp ( Arnemo, J. M., Ahlqvist, P., Andersen, R., Berntsen, F., Ericsson, G., Odden, J., Brunberg, S., Segerström, P. & Swenson, J. E Risk of capture-related mortality in large free-ranging mammals: experiences from Scandinavia. Wildlife Biology 12: ( Arnemo, J. M., Dypsund, P., Berntsen, J., Schulze, J., Wedul, S. J., Ranheim, B. & Lundstein, L. Use of intraperitoneal radiotransmitters in large carnivores [in Norwegian with English abstract]. Norsk Veterinærtidsskrift 1998; 110: Arnemo, J. M., Linnell, J. D. C., Wedul, S. J., Ranheim, B., Odden, J., Andersen, R.. Use of intraperitoneal radiotransmitteres in lynx kittens (Lynx lynx): anaesthesia, surgery and behaviour. Wildlife Biology 1999: 5: ( tens.pdf) Arnemo, J. M. & Fahlman, Å Biomedical Protocols for Free-ranging Brown Bears, Gray Wolves, Wolverines and Lynx. Norwegian School of Veterinary Science, Tromsø, Norway. ( Linnell, J. D. C., Andrén, H., Liberg, O., Odden, J., Skogen, K. & Andersen, R Scandlynx: a vision for coordinated lynx research in Scandinavia. NINA Report 86:1-25.( 7