Using Genetics to Evaluate the Success of a Feral Cat (Felis catus) Control Program in North-Western Australia

Abstract

Simple Summary: The management of invasive species is a major challenge for the conservation of biodiversity globally. One technique that has been widely used to control feral cats (Felis catus) and red foxes (Vulpes vulpes) in Western Australia is the aerial broadcast of toxic baits, but assessing its efficacy can be difficult. Here, we report on a method of evaluating the effectiveness of this method for the abatement of feral cats using genetic analysis techniques. However, our results were unable to provide robust evidence that, over a five-year program, baiting had a detrimental impact on both genetics and demography in this population, and the results were not significant. Monitoring the impact of control programs in this way may provide valuable information to managers on the effectiveness of their management strategy, but further refinement of the methodology is recommended. Abstract:The feral cat has been implicated in the decline and extinction of many species worldwide and a range of strategies have been devised for its control. A five-year control program using the aerial broadcast of toxic Eradicat ® baits was undertaken at Fortescue Marsh in the Pilbara region of north-western Australia, for the protection of biodiversity in this important wetland area. This program has been shown to have had a significant detrimental effect on cats in this landscape, but the long-term impact is difficult to ascertain. We assessed population genetics across three cohorts of feral cats sampled as part of the control program. We also compared cat populations in natural habitats and around human infrastructure. A key challenge in any study of wild animal populations is small sample sizes and feral cats are particularly difficult to capture and sample. The results of this study superficially appear to suggest promising trends but were limited by sample size and many were not statistically significant. We find that the use of genetic techniques to monitor the impact of invasive species control programs is potentially useful, but ensuring adequate sample sizes over a long enough time-frame will be critical to the success of such studies.

Molecular detection of feline hemoplasmas and retroviruses in free-roaming and shelter cats within a university campus

“…Differences in the mean PCV values were statistically significant (Student's t-test, P = 0.037), such that the mean PCV was 28.2% (95% CI [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] for positive cats and 34.6% (95% CI [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] for negative cats (Table 1). Although hemoplasmas have been shown to be opportunistic pathogens associated with arthropod-borne diseases, 37 previous studies on the same cat population found anti-T gondii (Fisher's exact test, P = 0.06), anti-Rickettsia rickettsii (Fisher's exact test, P = 0.07) and anti-R parkeri (P = 0.38) antibodies that did not present any associated risk factor for coinfection.…”

“…This may impair extrapolation of the findings to the whole population, particularly with regard to free-roaming cats. 30 This small, free-roaming cat sample was a result of difficulties in catching the cats, 32 together with the potential *Indirect immunofluorescence assay was used to determine serological status 30,31 OR = odds ratio; CI = confidence interval; FIV = feline immunodeficiency virus; FeLV = feline leukemia virus risk to life posed by trapping, the temporary duration of permission for sampling from the campus and an excess of cat food offered by visitors to the campus at several (more than 40) campus locations, which strongly competed with cat bait traps. A more representative free-roaming cat sample is needed in future studies, and this should extend to other university campuses.…”

“…31 The relatively low number of free-roaming cats sampled reflected difficulties in catching them, as previously documented in studies conducted on feral cats. 32 The sampled cats were examined for ticks and fleas; when found, these were collected and preserved in isopropyl alcohol, followed by taxonomic identification using morphological keys. 33 Molecular analyses DNA extraction was performed using a commercial kit (Illustra Blood Genomic Prep Mini Spin Kit; GE Healthcare), following the manufacturer's recommendations.…”

The Promise of Genetics and Genomics for Improving Invasive Mammal Management on Islands

“…Different classes of molecular markers have been employed in invasive species research, historically including protein-based allozymes, polymorphic nuclear and organellar DNA fragments [e.g., restriction/amplified fragment length polymorphisms (RFLPs/AFLPs), mitochondrial/chloroplast DNA (mtDNA/cpDNA), respectively], and hypervariable tandemly repeated DNA sequences (e.g., microsatellites and minisatellites; Le Roux and Wieczorek, 2009). Microsatellites and mtDNA, in particular, have seen frequent application in IMS research (Browett et al, 2020), although they may not be sensitive enough to reconstruct invasion histories and delineate eradication units in recently diverged populations or those exhibiting contemporary gene flow (Cowen et al, 2019;Yoshida et al, 2020).…”

Two Methods of Monitoring Cats at a Landscape-Scale

“…From an economic perspective, it is essential that we measure the outcomes of the pre- and post-management abundance of cats. Cats can breed rapidly, potentially doubling in abundance each year [ 25 ], and disperse over long distances [ 26 , 27 ]. This allows populations of feral cats to potentially recover quickly post-management.…”