What is better for animal conservation translocation programs : soft‐ or hard‐release? A phylogenetic meta‐analytical approach

Resende, PS, Viana‐Junior, AB, Young, RJ ORCID: https://orcid.org/0000-0002-8407-2348 and Azevedo, CS ORCID: https://orcid.org/0000-0003-0256-9017 2021, 'What is better for animal conservation translocation programs : soft‐ or hard‐release? A phylogenetic meta‐analytical approach' , Journal of Applied Ecology, 58 (6) , pp. 1122-1132.

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Access Information: This is the peer reviewed version of the following article: Resende, P.S., Viana‐Junior, A.B., Young, R.J. and Azevedo, C.S. (2021), What is better for animal conservation translocation programs: soft‐ or hard‐release? A phylogenetic meta‐analytical approach. Journal of Applied Ecology., which has been published in final form at https://doi.org/10.1111/1365-2664.13873. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.


Animal conservation translocation is an important tool available to conservation biologists to address problems of isolated, declining or endangered populations. This approach includes both captive‐bred and free‐ranging origin animals, which are used to rescue genetically limited populations and re‐establish extirpated populations. Both soft and hard release protocols (the release of animals with or without acclimatization, respectively) are used in animal conservation translocation programs; however, there is no consensus on whether one has better conservation outcomes than the other. Here, we analyzed data from 17 studies to measure the efficiency of both techniques for fauna conservation. Using phylogenetic meta‐analysis, we compared results from articles that used soft and hard release protocols to determine the overall effect size. In addition, we examined if the success metrics, type of environment, taxonomic group, and animal’s origin affected the outcomes of each type of translocation programs. We calculated 61 effect sizes for 17 species. We found that the soft‐release protocol is approximate 40% better than the hard‐release protocol (Estimates = 0.44, CI95: 0.11 – 0.76). Soft‐release program increased success by 77% (Estimates = 0.78, CI95: 0.37 ‐ 1.19) when movement metrics were used (as compared to hard‐release) and were 41% more successful with terrestrial species. In general, soft releases showed better outcomes by reducing movements away from the release site, but this was driven mostly by terrestrial reptile translocations (77% chance of success); when birds and mammals or the other success metrics were evaluated, both release techniques had similar effects. Lastly, the origin (i.e. captive or wild) of the released animals did not influence the success rate of soft‐ vs. hard‐releases. Synthesis and Applications. We conducted a meta‐analysis to evaluate which is the best release protocol for success in animal conservation: soft‐ or hard‐release. Our results showed that soft‐releases are in general better than hard‐releases, especially for reptiles. Protocol outcomes were similar for birds and mammals and were not linked to the origin of the released animals. We recommend that the decision of which protocol to use needs also to consider the financial costs of the used protocol.

Item Type: Article
Additional Information: ** Article version: VoR ** From Crossref journal articles via Jisc Publications Router **Journal IDs: pissn 0021-8901; eissn 1365-2664 **History: issued 20-03-2021; published_online 20-03-2021 **License for this article: starting on 20-03-2021, , http://onlinelibrary.wiley.com/termsAndConditions#vor
Schools: Schools > School of Environment and Life Sciences
Journal or Publication Title: Journal of Applied Ecology
Publisher: Wiley
ISSN: 0021-8901
Related URLs:
Funders: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Coordination for the Improvement of Higher Education Personnel), Biodiversity Research Consortium Brazil-Norway (BRC), Hydro-Alunorte
SWORD Depositor: Publications Router
Depositing User: Publications Router
Date Deposited: 30 Mar 2021 14:05
Last Modified: 20 Mar 2022 02:30
URI: https://usir.salford.ac.uk/id/eprint/59955

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