Dataset: An invasive commensal and a native marsupial maintain disease vector populations at the urban fringe

The dataset contains numbers of larval, nymphal, and adult ticks collected from small mammals in Sydney's Northern Beaches as part of the project focused on identifying the important hosts of urban ticks. The dataset includes unique animal ID numbers, date of sampling, season, transect (1, 2, or 3), animal sex (M = male, F = female), weight, and species. Study abstract: Vertebrate communities change in response to urbanisation with important flow-on effects for the arthropod disease vectors that use them as hosts. Ticks are major vectors of disease globally making it increasingly important to understand how altered vertebrate communities in urban areas shape tick dynamics and disease risk. Despite looming public health crises in Australian urban landscapes, little is known about which native and introduced small mammals maintain tick populations preventing host-targeted management and leading to human-wildlife conflict. To address this, we determined 1) larval, nymphal, and adult tick abundances on host species and effects of season, host sex and size, 2) the number of ticks supported by the different host populations (tick abundance on each species multiplied by their abundance) and 3) the proportion of medically significant tick species feeding on the different host species in Northern Sydney, Australia. We counted 3551 ticks on 241 individual mammals at 15 sites and found that long-nosed bandicoots hosted more ticks of all life stages than other small mammals but introduced black rats were more abundant at most sites (33-100%) and therefore important in supporting larval and nymphal ticks in our study areas. Black rats and long-nosed bandicoots hosted a greater proportion of medically significant tick species including Ixodes holocyclus and Ixodes tasmani compared to other hosts. Our results show clearly that an introduced commensal contributes to the maintenance of urban tick populations and suggests that ticks could possibly be managed by controlling rat populations on urban fringes.The dataset is the raw data. Details of sample collection: For each captured mammal, we first recorded species, weight, sex, and reproductive status. Animals were lightly anaesthetised using isoflurane vaporised in medical grade oxygen. To induce anaesthesia, isoflurane was delivered at a concentration of 2-5% and lowered to 1% for maintenance. We then systematically searched the entire body for ticks within a 10-minute timeframe (~1-2 min per body part: head, body, axilla, genitalia, and limbs), recording the number of each life stage found. Total processing time was limited to a total of 30 minutes, which included anaesthetic induction and recovery times, the latter of which was up to 10 minutes for some individuals. Thus, our search time aimed to balance obtaining an accurate estimate of tick burden with minimising the impact on animal welfare (Lydecker et al. 2019a). A subset of ticks was removed from each individual and stored in 70% ethanol for later identification. All animals were provided with inhaled oxygen and kept warm until fully recovered and alert. We marked individuals by clipping a section of fur on the back to avoid sampling recaptures within the same trapping session then released recovered animals at the capture point