CITES | Animal Health and Welfare | Biodiversity

Marking wild birds-animal welfare risks


Report no: VKM Report 2024: 03

Published: 03.05.2024

Key message:

The capture, handling and marking of wild birds requires ethical trade-offs between the risk of possible harm to individual birds and the need to acquire knowledge. The effects on welfare vary between methods and groups of birds.


Ethical considerations with respect to the capture, handling, and marking of wild birds must balance the risk of potential harm to individual birds against the need to obtain the necessary data to address goals in basic science, as well as conservation targets for species and ecosystems. The Norwegian Environment Agency and the Norwegian Food Safety Authority requested an updated knowledge base on methods for capture, handling, and marking of wild birds for scientific and management purposes, and associated risk-reducing measures.


The assessment includes any bird species belonging to orders of birds that are represented on the Norwegian mainland, other land areas where Norwegian law applies, or in Norwegian territorial waters; and methods that require a permit from the National Animal Research Authority, a bird ringing license and/or a wildlife permit from the Norwegian Environment Agency. Assessments of potential impacts of physical sampling methods were also included. Regarding the 3Rs approach, this report does not address whether field studies of wild birds should be replaced with alternative approaches or if the number of marked birds should be reduced but instead focuses on the refinement of methods in cases where marking is regarded as the most appropriate and adequate method.

Definition of animal welfare. The VKM project group established a common understanding of animal welfare and its indicators in free-living wild birds. We adopted an approach that synthesized the guidance on animal welfare risk assessment from the European Food Safety Authority with the Five Domains Model framework that evaluates impacts on indicators of 1: nutrition, 2: physical environment, 3: health, 4: behavioral interactions, and 5: mental state.

Evidence base. A list of 92 benchmark papers was compiled for the capture, handling, sampling, and marking of wild birds. Due to resource constraints and a lower urgency in updating the risk assessment for capture and handling methods, a full systematic literature search was only conducted for marking and tracking. The search was conducted by targeting peer-reviewed articles. Metadata was extracted from the 190 included articles, comprising 732 studies. Evidence of the impacts of capture, handling, and sampling was based on information from the list of benchmark papers, the extensive libraries and first-hand experience of project group members, and additional searches.

Risk assessment method. We employed the Five Domains model as a conceptual framework for evaluating risks to animal welfare and developed rubrics and score sheets for a systematic approach. Assessments were conducted separately for each capture, handling, sampling, and marking method. If a method has varying effects on different groups of birds, separate assessments have been conducted for each group of birds. For each method, the overall risk is assessed as either Low, Moderate, or High, and depicted in a matrix, with the probability of negative impact on the x-axis and the potential magnitude of negative impact on the y-axis. Additionally, the level of confidence in each assessment is indicated, considering the quality and quantity of the evidence.


If conducted by trained personnel following best practices, all the methods for capture, handling, or sampling were assessed as low or moderate risk for short-term or long-lasting harm to animal welfare. Among the different methods for marking and tagging of wild birds, temporary feather dyes and PIT tags were assessed as low risk, while glue and tape methods, tail mounted tags, necklace collars, and surgical implants were assessed as low or moderate risk, and flipper tags on penguins as high risk. Metal and colour rings, leg flags, patagial wing and web tags, neck bands, nasal discs and saddles, sutures and subcutaneous anchors, leg mounted tags, leg-loop and backpack (thoracic) harness were assessed as low, moderate, or high risk, depending on group of birds. The substantial heterogeneity in the impacts on animal welfare among methods and different groups of birds means that thorough pre-investigation, planning, and preparations are required for safe capture, handling, sampling, and marking of wild birds.

Risk-reducing measures

In addition to measures provided for each specific field method assessed, we have identified five key measures that would reduce the probability of adverse impacts on animal welfare: (1) follow best practises; (2) conduct pilot and effect studies; (3) ensure training routines; (4) standardise assessments and encourage reporting of animal welfare effects; and (5) continuing efforts to address the 3Rs with refinement and reduction to improve animal welfare.

The assessment spans subject areas for three of VKM's panels and is approved by a separate approval group.


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