Methods for marking New Zealand wildlife: Amphibians, reptiles and marine mammals

151 Pages·2011·1.56 MB·English

Methods for marking
New Zealand wildlife
Amphibians, reptiles and marine mammals
Ngaio J. Beausoleil, David J. Mellor, Kevin J. Stafford
Methods for marking
New Zealand wildlife
Amphibians, reptiles and marine mammals
Ngaio J. Beausoleil, David J. Mellor, Kevin J. Stafford
Cover: Archey’s frog (Leiopelma archeyi) Multi-imaging device records four different image angles of
each frog in a single digital photograph, allowing rapid documentation of natural markings which can
be used to identify individual frogs. Photo: Avi Holzapfel, DOC.
This literature review was funded by DOC (investigation no. 3489). The report was prepared for
publication by DOC Science Publishing, Science & Research Unit; editing by Sue Hallas and Helen
O’Leary, layout by Ruth Munro, project management by Jaap Jasperse and Don Newman. Publication
was approved by the Manager, Science & Research Unit, Science Technology and Information Services,
Department of Conservation, Wellington.
All DOC Science publications are listed in the catalogue which can be found on the departmental web
site http://www.doc.govt.nz
© Copyright 2004, New Zealand Department of Conservation
ISBN 0–478–22631–4
In the interest of forest conservation, DOC Science Publishing supports paperless electronic
publishing. When printing, recycled paper is used wherever possible. Printed by Astra Print,
Wellington, New Zealand.
This book may be cited as: Beausoleil, N.J.; Mellor, D.J.; Stafford, K.J. 2004: Methods for marking New
Zealand wildlife: amphibians, reptiles and marine mammals. Wellington, Department of Conservation.
147 p.
Corresponding author: D.J. Mellor, Animal Welfare Science and Bioethics Centre, Massey University,
Private Bag 11-222, Palmerston North, New Zealand. Email: [email protected]
ii .
Contents
Introduction 1
Why mark wildlife? 1
General safeguards for marking wildlife 2
The ideal mark 2
Selecting an appropriate marking method 3
Specific objectives of the study and the nature of the data required 4
Duration of the study 4
Level of recognition required 5
Life history and physical attributes of the species involved 5
Welfare of the animals involved 6
Size and conservation status of population 8
Amount of time and resources available to researchers 9
Level of training and experience of researchers 9
Extent of public access to the study site 10
Responsibilities of scientists 10
Direct evaluation of the effects of marking 11
Appropriate methods for marking New Zealand wildlife 13
Amphibians 13
Reptiles 14
Cetaceans 14
Pinnipeds 15
Methods 17
Temporary marks 17
Painting 18
Dyeing 19
Attached devices 19
Hair removal 19
Fluorescent powders 20
Radioisotope marking 21
Semi-permanent marks 23
Tags 23
Collars, harnesses or bands 24
Nocturnal lights 25
Telemetry 26
Permanent marks 28
Hot branding 29
Freeze branding 30
Chemical branding 32
Tattooing 32
Passive Integrated Transponders 33
Visible Implant Fluorescent Elastomer tags 35
Tissue removals 36
Autotransplantation 37
Vital stains 38
. iii
Natural marking identification 38
Amphibians 41
Temporary marks 42
Semi-permanent marks 46
Permanent marks 51
Natural marking identification 65
Summary 67
Reptiles 69
Temporary marks 70
Semi-permanent marks 76
Permanent marks 80
Natural marking identification 86
Summary 87
Marine mammals—cetaceans 89
Temporary marks 90
Semi-permanent marks 90
Permanent marks 99
Natural marking identification 100
Summary 103
Marine mammals—pinnipeds 105
Temporary marks 106
Semi-permanent marks 109
Permanent marks 116
Natural marking identification 122
Summary 123
References 125
iv .
Introduction
Marking individuals or groups of animals is an integral part of wildlife research
and management, and usually involves the application of an artificial mark.
However, marking can affect the animals by altering: their behaviours or
interactions with their own or other species; their health and welfare; their
capacity to survive or reproduce; population dynamics; ecological balance and
other factors. Such disturbances should be minimised for ethical, scientific and
practical reasons. This can be done by recognising the advantages and
disadvantages of different marks and marking procedures, and by employing the
most effective and humane ways of applying the chosen marks (Mellor et al.
2004).
The purpose of this book is to describe key features of marking methods that
have particular relevance to New Zealand species. Therefore, the information
presented refers mainly to methods that have been or may be used to mark New
Zealand wildlife. Information on other species is included when there are no
reports of marking similar New Zealand species. Likewise, information on
methods used in dissimilar species is included if their use seems plausible in
New Zealand species, or if such information is deemed to be of value in some
other way. It must be noted that this book does not explicitly address the
effects of capture and handling on wild animals, but concentrates on the effects
of the application, wearing and observation of identifying marks.
It is recommended that the whole of the Methods section be read before the
sections on the different animal groups because information presented in that
section is applicable and important to all groups. In addition, reference should also
be made to the general safeguards, practical and animal welfare considerations and
information about public perceptions associated with each marking method. These
issues are discussed in the companion document entitled Marking amphibians,
reptiles and marine mammals: animal welfare, practicalities and public
perceptions in New Zealand (Mellor et al. 2004).
WHY MARK WILDLIFE?
Often it is necessary in wildlife research to mark individuals or groups of
animals. Reasons for marking animals include:
• To identify individuals or groups of animals to study demographics,
behaviour, ecology and other aspects of the lives of wild animals.
• To estimate population size and to determine rates of survival, reproduction
and recruitment within specific populations.
• To identify particular stocks and rates of stock mixing (this type of
information is used extensively to monitor populations undergoing
conservation management).
• To identify individual animals in behavioural studies.
• To develop and verify aging techniques and to ascertain growth rates in
individual animals.
Wildlife marking methods: Introduction 1
GENERAL SAFEGUARDS FOR MARKING
WILDLIFE
Regardless of the method chosen for marking a population of animals, there are
general safeguards that researchers have an ethical duty to apply (Mellor et al.
2004).
• It must be demonstrated that marking is necessary to achieve the proposed
research objectives.
• The purposes and benefits of the method chosen must be sufficient to justify
its adverse effects.
• Devices and methods must be selected carefully (see, Selecting an
appropriate marking method, pp. 3–10).
• Personnel should assess marking procedures that are new, or new to the
particular population, or modifications of existing methods, on captive
individuals or allied species before attempting to mark wild populations.
• Mark-related effects on parameters such as survival, reproductive success,
behaviour and intra- and inter-specific interactions must be quantitatively and
objectively assessed, and measures devised to minimise them. Both short- and
long-term effects should be evaluated, and effects should be assessed
separately in all age groups and sexes to be marked (see, Direct evaluation of
the effects of marking, pp. 11–13).
• Data analysis must take account of mark-related effects.
• Only experienced and/or well-trained personnel who are proficient in the
method should carry out marking.
• Since handling may cause short-term stress, use gentle and minimal handling,
and for the shortest time possible.
• Accidental injury during marking should be treated, and if sufficiently serious,
the animal should be humanely euthanased.
• Personnel must minimise the transmission of infectious diseases and parasites
between animals during the marking procedure.
• Whenever possible, personnel should monitor the health and welfare of
marked animals.
• Whenever appropriate, personnel should remove devices at the end of the
study.
• Devices applied to juvenile or growing animals should be designed to expand
or drop off.
• Marking should not compromise conservation strategies for endangered or
threatened species (e.g. kill methods or those that adversely affect
reproduction should not be used), nor should it adversely affect the ecological
balance or the environment.
THE IDEAL MARK
Ideally, an identifying mark should meet all of the following criteria (Lewke &
Stroud 1974; Ferner 1979; Neitfeld et al. 1994; Reaser 1995).
2 Beausoleil et al.—Wildlife marking methods
An ideal mark should:
• Allow the animal to be as free of pain and/or stress1 as possible.
• Identify the animal as an individual, if desired.
• Be easy to apply in both the laboratory and the field.
• Be easily and unambiguously read or observed.
• Be reliable over the duration of the study.
• Be cost-effective.
• Be adaptable to animals of different sizes.
• Utilise materials that are easy to obtain.
An ideal mark should not:
• Cause death.
• Have sub-lethal effects on fitness, e.g. reduced growth or reproductive rates.
• Influence the behaviour of marked individuals.
• Influence the behaviour of other animals towards the marked individual.
• Affect the future probability of capturing marked individuals relative to
unmarked individuals.
Of course, no one marking method is able to satisfy all of these criteria; there is
no ideal method of marking wild animals. There will always be a trade-off
between the acquisition of knowledge and the disturbance caused by acquiring
it. In order to study natural systems, we must necessarily disturb them; the
undisturbed system is unknown. Some might argue that data collected from
systems disturbed by marking do not reflect that system as it functions
normally. However, if studies are biologically and ethically sound, their benefits
should outweigh the detriment caused by such investigations. Selection of a
marking method depends primarily on the ability of the method to fulfil the
objectives of the study, while causing the least overall impact on the animals
involved (Ehmann 2000).
SELECTING AN APPROPRIATE MARKING
METHOD
The most appropriate method may differ with species, population, sub-
population, season, research group and many other factors. Therefore,
researchers must be rigorous and consistent in their assessment of the most
biologically and ethically appropriate marking method for the animals under
study. Acceptable methods should be determined by individual researchers,
research institutes (e.g. through Animal Ethics Committees) or governing
bodies, and should reflect the goals and limitations of the particular study.
Selection of the appropriate marking method should involve careful
1 Stress represents physiological responses to significant challenges, which can be emotional and/or
physical. They elicit well-documented ‘fight-or-flight’ responses and changes that help to deal with
possible injuries. Externally observable signs of stress include aggression, struggling or freezing
behaviours, abnormal postures, vocalisation or its absence, impaired grooming, altered activity
patterns, shivering, altered breathing, change in skin colour and body temperature change. The
associated physiological responses may be measured.
Wildlife marking methods: Introduction 3
consideration of the following issues (Ferner 1979; Heyer et al. 1994; Reaser
1995; Baker & Johanos 2002):
• Specific objectives of the study and the nature of the data required.
• Duration of the study.
• Level of recognition required.
• Life history and physical attributes of the species involved.
• Welfare of the animals involved.
• Size and conservation status of the population.
• Amount of time and resources available to researchers.
• Level of training and experience of researchers.
• Extent of public access to the study site.
Specific objectives of the study and the nature of the data
required
A marking method should be able to provide the level and nature of information
required to meet the specific objectives of the study. For example, there would
be little point in using a marking method that allowed only recognition of
marked versus unmarked animals in a study of social behaviour, when a method
that identified individual animals would provide more valuable information.
Similarly, if information on the undisturbed behaviour of the animals is
required, then marks should allow remote identification of individuals or
groups.
The marking method selected should not influence the variables under study.
Marks and marking procedures can alter the behaviour, reproductive success,
intra- and inter-specific interactions and survivability of the bearer. For
example, a mark used to estimate the annual survivorship of individuals in a
population should not alter an animal’s conspicuousness to potential predators.
Any data collected using such a mark would misrepresent the natural survival
rate of that population. Similarly, if the objective of a study is to determine the
annual number of reproductive events in a population, a mark that affects the
capacity of an animal to engage in mating behaviour or that influences the
bearer’s attractiveness to conspecifics, will have a significant effect on the data
collected. It is not only negative changes in such variables, but also positive
changes, that can adversely affect the data collected, and subsequent outcomes.
Duration of the study
A mark must be effective for the duration of the study. A mark that is lost before
the conclusion of a study can seriously bias the results. For example, tag loss in
demographic studies of Antarctic seal species can cause overestimation of
population size, which might affect the design of conservation strategies. In
addition, if a mark is lost prematurely, the marked animal may have suffered
because of marking without any redeeming benefit in terms of knowledge
gained. This type of imbalance cannot be ethically justified. Researchers have
an obligation to select a method that has been proven to last for the appropriate
amount of time when applied to the species of interest. If the durability of a
mark is unknown, the researcher has an obligation to conduct a preliminary
study to determine how long the mark will endure and allow accurate
identification (e.g. be legible).
4 Beausoleil et al.—Wildlife marking methods
If mark loss is inevitable, as is the case with tags used in seal species, the rate of
mark loss must be calculated, and this rate must be incorporated into the results
of the study and its outcomes (e.g. modelled population estimates). It is
important that estimated rates of mark loss be specific to the marking
equipment, species and habitat in question, as loss rates vary greatly with these
factors. Other factors that may affect the rate of mark loss include operator
technique and experience, which are inherently difficult both to standardise
and quantify.
If a less harmful, temporary mark is sufficient then this type of method should
be used in preference to a more invasive, longer-lasting mark. The use of a
temporary mark will mean that the effects of marking are also likely to be short
term. Conversely, if a temporary mark is lost before the end of a study, any harm
associated with that mark would be unjustifiable, and a more permanent
method should have been used.
Level of recognition required
Proximity
Researchers must decide the distance at which they require recognition of the
mark. Some marks allow identification of marked animals from a considerable
distance. Others, especially those on small animals, require recapture and
handling of the marked animals to identify them. If minimising disturbance is of
primary importance to the study objectives or to the welfare of the animals,
then the marking method should allow recognition at a distance, without
recapture and handling. However, researchers must be aware that marks
allowing remote identification or recognition are also likely to increase the
conspicuousness of the bearer to predators or prey, or can alter the appearance
enough to affect intraspecific interactions.
Specificity
Some studies require that marked animals be distinguished only from unmarked
animals. For example, estimates of population size do not require identification
of individual animals. Mathematical models are used to convert sample numbers
(ratio of marked to unmarked animals) into estimates of the total population
size. In contrast, most ethological studies require the identification of
individuals to assess facets of animal behaviour such as predator–prey
interactions, home ranges, habitat use, foraging and reproductive behaviours
and social interactions. A mark that does not identify the animal as an individual
is of little use in such studies.
Life history and physical attributes of the species involved
The physical and anatomical attributes, habits and ecology of a species will play
a major role in deciding which marking method is appropriate. A method
appropriate for use in whales is unlikely to be useful for studying frogs.
Physically, the animal’s size, the presence or absence of appendages, and tissue
characteristics are some of the features that will influence mark choice. Small
size limits the use of certain marking methods, primarily because of the need for
low mark-to-body weight ratios. This ratio should not exceed 10%, but devices
should be kept as small as possible (American Society of Mammalogists 1987;
Heyer et al. 1994).
Wildlife marking methods: Introduction 5