Why catch when you can throw? A framework for tagging animals without capture or restraint

Abstract Background: The attachment of electronic tags to animals has led to data collection that has hugely enhanced our understanding of wild animal behavioural ecology and physiology. However, animals are normally captured and restrained/sedated so that the tags can be attached, which is stressful for the animals and threatens to compromise the quality of the data gathered, at least during an initial acclimation period. We note that many plant seeds have evolved to become attached to passing animals and suggest that an approach, based on plant burs, could be used to attach tags to animals without capture or restraint. Methods: We present a framework for ‘bur-tagging’ and provide details of the design of a bur-tagging system, highlighting issues that we feel should be considered for the approach to be successful. Results: We report how the tagging site in the environment and animal neophobia critically affect the probability that an animal will be tagged over any given time period and also document what needs to be done to ensure that only the target species is tagged as well as illustrating the steps that can be taken to enhance the accuracy of tag placement on the animal. In addition, we discuss the criticality of the choice of the adhesive mechanism between the tag and the animal and illustrate how animals react to being tagged using this system. Conclusion: Although in an early stage of development, we believe that ‘bur-tagging’ shows great promise for deploying sophisticated electronic tags on wild animals with less stress than the conventional capture and restraint approach.