Major advancements in ecology and biodiversity conservation have been made thanks to methods for marking and individually tracking animals. Marking animals is both widely used and controversial due to the potential consequences for animal welfare, which are often incompletely evaluated prior to implementation. Two outstanding knowledge gaps concerning the welfare consequences of individual marking are their short-term behavioural impacts and the relative impacts from marking versus the handling of animals while carrying out procedures. We addressed these knowledge gaps through an experimental study of alpine newts (Ichthyosaura alpestris) in which we varied handling and marking procedures. Examining individual responses to handling, toe clipping and visible implant elastomer (VIE) injection over 21 days showed that handling and marking elicited increased newt activity and hesitancy to feed compared to animals that did not get handled or marked. These effects were apparent even when animals were handled only (not marked), and marking did not further increase the magnitude of responses. Increases in newt activity and feeding hesitancy were transient; they were not observed in the weeks following handling and marking. While previous studies emphasise the welfare impacts of marking procedures themselves, these findings highlight that handling alone can elicit behavioural changes with possible costs to welfare. Yet, the transient nature of behavioural responses suggests that immediate costs of handling may be subsequently compensated for in the short term.

Conservation biology and animal welfare science are multidisciplinary fields of research that address social concerns about animals. Conservation biology focuses on wild animals, works at the level of populations, ecological systems and genetic types, and deals with threats to biodiversity and ecological integrity. Animal welfare science typically focuses on captive (often domestic) animals, works at the level of individuals and groups, and deals with threats to the animals’ health and quality of life. However, there are many areas of existing or potential overlap: (i) many real-life problems, such as environmental contamination, urban development and transportation, create problems for animals that involve both welfare and conservation; (ii) research methods from each field are needed to address some of the scientific problems of the other; and (iii) policies and practices targeting either conservation or animal welfare may prove unproductive if they do not take account of both areas of concern. Moreover, scientists in both fields face the common challenge of applying science to guide policy and practice, often to issues that are both empirical and ethical, and often under conditions of uncertainty. There are many cases where communication and co-operation between the fields should lead to better science and better practical outcomes.

Policy-making concerned with animals often includes human interests, such as economy, trade, environmental protection, disease control, species conservation etc. When it comes to the interests of the animals, such policy-making often makes use of the results of animal welfare science to provide assessments of ethically relevant concerns for animals. This has provided a scientific rigour that has helped to overcome controversies and allowed debates to move forward according to generally agreed methodologies. However, this focus can lead to policies leaving out other important issues relevant to animals. This can be considered as a problem of what is included in welfare science, or of what is included in policy. This suggests two possible solutions: expanding animal welfare science to address all ethical concerns about animals’ interests or widening the perspective considered in policymaking to encompass other important ethical concerns about animals than welfare. The latter appears the better option. This requires both a ‘philosophy of animal welfare science’, a ‘philosophy of decision-making about animals’, and greater transparency about what is included or excluded from both animal welfare science and the politics of animal policy.