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On the use of body mass measures in severity assessment in laboratory passerine birds

Lookup NU author(s): Dr Clare Andrews



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


© 2022 Universities Federation for Animal Welfare. Criteria for assessing the severity of scientific procedures in laboratory rodents include the loss of body mass. However, guidance is limited for passerine birds and application of criteria developed for mammals risks poor welfare decisions. Here, I ask whether, and how, body mass criteria could be incorporated into laboratory welfare assessment of passerines. Passerine birds strategically adjust their body mass to minimise combined mortality risk from starvation and predation. A systematic literature review found that strategic mass changes can be sizeable (sometimes > 10%) even over short timescales. Many aspects of a bird's current or past environment, including husbandry and experimental procedures, may alter perceived starvation or predation risks and thus drive strategic mass change via evolved mechanisms. Therefore, body mass criteria used for rodents may be too stringent for passerines, potentially leading to over-estimated severity. Strategic mass changes might obscure those stemming from experimental interventions yet could also offer insights into whether birds perceive an intervention or altered husbandry as a threat. Mass criteria for severity assessment should be species- and context-specific in order to balance needs for refinement and reduction. To guide the development of appropriate criteria, a future research priority is for greater data collection and sharing based on standardised routine monitoring of mass variation under a representative range of husbandry conditions and procedures.

Publication metadata

Author(s): Andrews CP

Publication type: Article

Publication status: Published

Journal: Animal Welfare

Year: 2022

Volume: 31

Issue: 3

Pages: 387-401

Print publication date: 01/08/2022

Acceptance date: 02/04/2018

Date deposited: 05/09/2022

ISSN (print): 0962-7286

Publisher: Universities Federation for Animal Welfare


DOI: 10.7120/09627286.31.1.013


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Funder referenceFunder name
666669Commission of the European Communities