Identifying black rat (Rattus rattus) movement patterns aids the development of management programs in citrus orchards

Abstract

Context The black rat (Rattus rattus) is an invasive species found throughout much of the globe, including in many agricultural areas, where they cause significant damage to many crops including citrus. Understanding how black rats move in these orchards would substantially aid the development of management programs to combat this pest species. Aim Our goal was to determine the home-range size and mean maximum distance moved over a 24-h period, as well as to determine the activity period for black rats in orchards. Methods We used innovative cellular tracking technology to provide a more complete assessment of home-range size and maximum daily movements than previously reported in other investigations. We also used remote-triggered cameras to assess activity periods for black rats to better inform management actions. Key results We observed large home ranges for black rats in citrus orchards ( x ¯ = 2.36     ha ). Although mean home-range size did not differ between males and females, we did identify an effect of sex on the mean maximum daily distance moved by black rats (males: x ¯ = 201     m ; females: x ¯ = 148     m ). Black rats were most active during the early evening, with all observations made during night-time. Conclusions Black rats moved relatively large distances within orchards, with activity occurring exclusively at night. Implications This information on black rat activity patterns will greatly assist in the development of management programs by informing ideal spacing between traps and bait stations to minimise cost, while still yielding efficacious results. A reliance on trapping or baiting during night-time would ensure access by black rats, while eliminating access to diurnal non-target species, although such actions would be labour-intensive and may be cost-prohibitive.