The impact of RHDV-K5 on rabbit populations in Australia: an evaluation of citizen science surveys to monitor rabbit abundance

Abstract

The increasing popularity of citizen science in ecological research has created opportunities for data collection from large teams of observers that are widely dispersed. We established a citizen science program to complement the release of a new variant of the rabbit biological control agent, rabbit haemorrhagic disease virus (RHDV), known colloquially as K5, across Australia. We evaluated the impact of K5 on the national rabbit population and compared citizen science and professionally-collected spotlight count data. Of the citizen science sites (n = 219), 93% indicated a decrease in rabbit abundance following the release of K5. The overall finite monthly growth rate in rabbit abundance was estimated as 0.66 (95%CI, 0.26, 1.03), averaging a monthly reduction of 34% at the citizen science sites one month after the release. No such declines were observed at the professionally monitored sites (n = 22). The citizen science data submissions may have been unconsciously biased or the number of professional sites may have been insufficient to detect a change. Citizen science participation also declined by 56% over the post-release period. Future programs should ensure the use of blinded trials to check for unconscious bias and consider how incentives and/or the good will of the participants can be maintained throughout the program.

Good intentions with adverse outcomes when conservation and pest management guidelines are ignored: A case study in rabbit biocontrol

“…We excluded all data relating to the national K5 release as this was a government coordinated activity that encouraged land managers to release K5 in March 2017. For our RHDV supply data this meant excluding all records for February 20, 2017; for our RHDV release data this meant excluding virus releases that were reported between March 1, 2017 and May 31, 2017, inclusive (Cox et al, 2019).…”

“…One of these variants is RHDV GI.1c, from the former Czech Republic (designated “v351”), initially released in Australia in 1995. However, because infection with a nonpathogenic rabbit calicivirus, endemic in south‐eastern Australia, offers cross‐protection to infection with this original virus (v351), a novel variant of RHDV, GI.1a, from South Korea (designated “K5”), was released through a coordinated national release program in 2017 (Cox et al, 2019; Le Pendu et al, 2017; Strive et al, 2013). Despite RHDV GI.1c and RHDV GI.1a both being intentionally released across Australia, another virus, RHDV GI.2 (RHDV2), emerged in 2015 and has become the dominant RHDV in the environment (Mahar et al, 2018).…”

Bayesian evaluation of temporal changes in sensitivity and specificity of three serological tests for multiple circulating strains of rabbit haemorrhagic disease virus

“…We monitored the RHDV1 and RHDV2 viruses in wild rabbit populations at 41 sites in Queensland, New South Wales, Australian Capital Territory, Victoria, South Australia and Western Australia (Cox et al, 2019). Monitoring occurred at approximate three-monthly intervals in Summer (January), Autumn (April), Winter (July) and Spring (October) between 2011 and 2021.…”

Immunological Cross-Protection between Different Rabbit Hemorrhagic Disease Viruses—Implications for Rabbit Biocontrol and Vaccine Development

“…Rabbit hemorrhagic disease virus (RHDV), a member of the genus Lagovirus in the family Caliciviridae, is used effectively as a biocontrol agent in Australia to reduce the significant environmental and economic impact of feral European rabbit ( Oryctolagus cuniculus ) populations [ 1 ]. Specifically, viruses within the GI.1 genotype are deliberately released as part of these control efforts, with a GI.1c (classical RHDV) virus in use since 1995 and a GI.1a (RHDV1a) virus in use since 2017 [ 2 , 3 , 4 ]. In addition to these intentionally released lagoviruses, a non-pathogenic rabbit calicivirus, GI.4 (RCV-A1), is endemic, while another virus, GI.2 (RHDV2), is currently the dominant pathogenic variant across Australia [ 5 , 6 ].…”

“…Rabbit biocontrol programs are very successful in Australia, with the resulting feral population decline delivering an estimated $1 billion AUD in economic and environmental benefits annually [ 1 , 3 , 9 ]. Nevertheless, both intentionally released and naturally circulating lagoviruses also have significant impacts on domestic rabbits.…”