Home range of feral cats on Rota Is.

Leo, B. T., Anderson, J. J., Brand Phillips, R., & Ha, R. R. (2016). Home range estimates of feral cats (Felis catus) on Rota Island and determining asymptotic convergence 1. Pacific Science, 70(3), 323-331.

Feral cats (Felis catus) have been shown to be a main contributor to species decline throughout the world and are especially threatening to insular species that lack appropriate defense characteristics. To mitigate the impact of feral cats on threatened species, space-use data are commonly used to design control strategies. In this article we report on the performance of GPS datalogging collars and provide baseline information on daily space use and home ranges of feral cats that threaten an endangered species on Rota Island in the Commonwealth of the Northern Mariana Islands. Using 100% Minimum Convex Polygon (MCP), average adult male home range was 1.32 km²(n = 2) and average adult female home range was 0.22 km²(n = 3). Home ranges were deemed fully revealed if asymptotes were approached using incremental analysis. Currently, there is no objective method for assessing where an asymptote is approached. Here, we describe a methodology to do so with the application of a Michaelis-Menten model to incremental data. We conclude that GPS datalogging collars are a viable tool for feral cat location data collection on Rota Island and that the Michaelis-Menten model is useful for determining asymptotic convergence of incremental location data.

An examination of feral cats control techniques for the protection of critically endangered species

Leo, B. T. (2016). An examination of predator control techniques for the protection of critically endangered species (Doctoral dissertation).

Feral cats (Felis catus) have been shown to be a main contributor to species decline throughout the world and are especially threatening to insular species that lack adequate defense characteristics. Feral cat control programs have been implemented on islands throughout the world with varied success. Many islands present unique limitations and therefore require custom control strategies. Furthermore, the adaptive nature of feral cat populations makes it difficult to predict space use and the effect of control on population size. To mitigate the impact of feral cats on threatened species, space use data are commonly used to design control strategies. With the use of GPS data logging collars, chapter two describes daily space use and home ranges of feral cats that threaten an endangered species on Rota Island in the Commonwealth of the Northern Mariana Islands. Using 100% Minimum Convex Polygon (MCP), average adult male home range was 1.32 km² and average adult female home range was 0.22 km². Home ranges were deemed fully revealed if asymptotes were reached using incremental analysis. A Michaelis-Menten model was applied to predict home ranges of cats with datasets that did not show convergence. The ability of the model to estimate home ranges of cats with limited location datasets was evaluated by comparing predictions derived from truncations of the full time series of complete datasets. Findings suggest that cat management on Rota should be multifaceted in order to maximize the protection of endangered species and that the Michaelis-Menten model is a useful tool for home range analysis. Chapter three examines the Rota hunting strategy to determine its impacts on the population. A discrete form of the Schaefer model was applied to a 29-month time series of control data. A likelihood framework was used to determine maximum likelihood parameter estimates and calculate population projections to compare control strategies. Model results suggest that the hunting strategy on Rota was effective at initially reducing the cat population, however an unfeasible amount of effort would be required to maintain such a rate of decline. Findings show that it is feasible to maintain cat abundance at lower levels and suggest that a concentrated-effort strategy is preferable to a fixed-effort strategy. While more complex population model forms are available, the Schaefer model is well suited for assessing the impacts of limited predator control programs, such as the one conducted on Rota Island.

Spatial ecology and prey choice of tagged feral cats

van der Ende, J. M. (2015). Spatial ecology and prey choice of tagged feral cats on Schiermonnikoog. M.Sc. Dissertation.  Master of Science in Geographical Information Systems (UNIGIS) Faculty of Economics and Business Administration Vrije Universiteit Amsterdam
The Netherlands

Feral cats (Felis catus) inhabiting the island Schiermonnikoog, The Netherlands, are a potential threat for local prey species populations. To improve the understanding and retrieve more insight in the spatial ecology of this invasive predator, ten feral cats (5 male : 5 female; 5 adult : 5 subadult) were equipped with GPS tags and followed from May till July 2014. Spatio-temporal analyses were used. The home ranges we calculated using Minimum Convex Polygon and Kernel density estimators and tested for differences in sex, age and time. The displacement distance and habitat use was compared between day and night. Locomotive behaviour was compared between subjects using a pre-defined dimension dyad with daily movement variables. In addition, scats were collected and analysed on prey remains and compared with the prey present in the area.
Average 3-month home ranges were found to be 81 and 158ha using Kernel density 95% and Minimum Convex Polygon 95% home ranges respectively. Home range sizes were not significantly different between sexes or age classes. However, nocturnal home range sizes were bigger than the diurnal ones. The nocturnal habitat use did differ from the diurnal use, suggesting a small preference for short salt marsh vegetation during the night. The cats showed a higher nightly displacement (M=45m/15min) compared to during the day (M=22m/15min). The cats were very variable in their daily migration (range M=198-528m) and cumulative daily displacement (range M=1.5-4.1km). A new visualisation technique was proposed to identify differences and similarities between the feral cats and seemed to work well. Hares (Lepus europaeus) contributed the most to the diet in terms of relative prey volume, but Common vole (Microtus arvalis) was the most numerous prey item found in the scats.
In conclusion this study describes the spatial ecology of feral cats and give new insights in the behaviour of feral cats in a natural part of a Dutch Waddensea island. The home ranges of males are not necessarily bigger than female ones. They tend to use short salt marsh vegetation more during the night which could indicate they hunt on the nocturnal species foraging there like hares and rabbits. Bird remains are found in the scats which indicate a potential threat for the bird population by this invasive introduced predator. However in this research no indication is found they actively search and hunt on birds. Further research using acceleration data might be useful to better quantify their hunting behaviour.

Smartphone and GPS for free-roaming dog population monitoring

Barnard, S., Ippoliti, C., Di Flaviano, D., De Ruvo, A., Messori, S., Giovannini, A., & Dalla Villa, P. (2015). Smartphone and GPS technology for free-roaming dog population surveillance-a methodological study. Veterinaria italiana, 51(3), 165-172.

Free-roaming dogs (FRD) represent a potential threat to the quality of life in cities from an ecological, social and public health point of view. One of the most urgent concerns is the role of uncontrolled dogs as reservoirs of infectious diseases transmittable to humans and, above all, rabies. An estimate of the FRD population size and characteristics in a given area is the first step for any relevant intervention programme. Direct count methods are still prominent because of their non-invasive approach, information technologies can support such methods facilitating data collection and allowing for a more efficient data handling. This paper presents a new framework for data collection using a topological algorithm implemented as ArcScript in ESRI^® ArcGIS software, which allows for a random selection of the sampling areas. It also supplies a mobile phone application for Android^®  operating system devices which integrates Global Positioning System (GPS) and Google Maps^TM. The potential of such a framework was tested in 2 Italian regions. Coupling technological and innovative solutions associated with common counting methods facilitate data collection and transcription. It also paves the way to future applications, which could support dog population management systems.

Corridors of introduced feral cats infringing ecologically sensitive areas in NZ

Recio, M. R., Seddon, P. J., & Moore, A. B. (2015). Niche and movement models identify corridors of introduced feral cats infringing ecologically sensitive areas in New Zealand. Biological Conservation, 192, 48-56.

The mitigation of the impact caused by introduced mammalian predators is a priority for conservation managers. Reducing predator population numbers is the most realistic strategy in mainland areas or large islands, and could be a feasible alternative to pest eradication. However, the success of control campaigns depends not only on removal of resident individuals, but also on managing reinvasions facilitated by connectivity with surrounding source populations. We combined niche analysis and fine-scale movement analyses of feral cats (Felis silvestris catus) to identify least-cost corridors from sources surrounding controlled areas of the ecologically sensitive area of Tasman Valley and Aoraki/Mt. Cook National Park, New Zealand. Intensive control of exotic predators has been executed during the last ten years in this area, where they pose a threat to native species such as endangered ground-nesting birds. Species distribution models revealed that cat distribution in the region was limited by its main prey, the European rabbit, and to mid-elevation (~ 1600 m) areas. Using GPS-tracking data and step-selection functions, we found that cats moved in an optimized fashion suggesting a maximum energy gain associated with high rabbit presence, while avoiding landscape obstacles such as rugged terrain. Connectivity between the high probability of cat presence in source and destination locations (in the control area) was facilitated by 1–3 corridors between valleys and multiple paths within valleys. Identification of least-cost paths, rooted in ecological and behavioral mechanisms underlying space use, can identify realistic putative corridors for focused implementation of control measures for introduced species in ecologically sensitive areas.

Dispersal of Feral Cats: Evidence from Genetics and GPS

Plummer, V. N. (2015). Dispersal of Feral Cats: Evidence from Genetics and GPS.
Invasive species are a considerable threat to many native habitats and species along with being considered a major cause of biodiversity loss . Economic damages associated with controlling invasive species and their effects amount to approximately $120 billion a year. Feral cats (Felis catus) are listed as one of the '100 world's worst invasive alien species'. There are as many as 70-100 million feral cats in the United States as well as an estimated 117-157 million domestic indoor and outdoor cats. Management efforts include nonlethal and lethal control methods. Nonlethal methods include a feeding and sterilization program known as "trap-neuter-release" (TNR) where cats are surgically sterilized and returned to the environment. Immigration may hinder TNR's success due to a decrease of natural mortality. Using genetic methods, the influence of immigrants on local population can be quantified and assessed. Microsatellite loci have been used for the analysis of natural population structure and molecular methods of identifying population structure can be a tool for the management and ecology of wildlife especially when paired with behavioral, demographic, or spatial information. The use of spatial information can aid in predicting the efficiency of different control strategies. GPS monitoring has been used on feral cats to study individual movements and interactions with environments, conspecifics and other species. Effective population control strategies should include a broad understanding of how feral cats occupy and move through the environment. The overarching goals of my study are to assess the amount of genetic variation of feral cat colonies on and around campus and to compare the distribution and movements of domestic and feral cats. To accomplish these goals I will 1) evaluate genetic diversity and population structure of feral cats through assessing microsatellite variation using 10 microsatellite markers and 2) determine home-ranges of domestic and feral cats through GPS technology.

Spatial ecology of feral cats on San Clemente Island

Bridges, A. S., Sanchez, J. N., & Biteman, D. S. (2015). Spatial ecology of invasive feral cats on San Clemente Island: implications for control and management. Journal of Mammalogy, 96(1), 81-89.

Feral cats, Felis catus, inhabiting San Clemente Island, California, are both predators and competitors of multiple sympatric endemic species. To improve our understanding and management of these invasive predators, we used GPS-equipped radiocollars to track 11 (6F:5M) cats for a total of 3,108 days, resulting in 15,419 GPS locations. Average 100% minimum convex polygon, 95% kernel density, and 50% kernel density estimates were 229, 132, and 33 ha, respectively. The point estimate for average male home-range size was larger than the average for females, but there was substantial variation among individuals of both sexes. Overlap indices indicated similar usage areas during nocturnal and diurnal time periods. Sample size limited our ability to definitively detect habitat preference, but data suggested areas within 50 m of roads were avoided, and that thicker land cover was preferred over open grasslands. Three test collars deployed within active cat home ranges indicated GPS locations were precise, with 96% of locations having < 10-m error estimates, and that horizontal dilution of precision indices were not useful in screening data. Our results describe feral cat spatial ecology on a semiarid island and can be used to inform population estimation, control, and mitigation programs.

Feral cat monitoring with GPS in NZ

Recio, M. R., Mathieu, R., Maloney, R., & Seddon, P. J. (2010). First results of feral cats (Felis catus) monitored with GPS collars in New Zealand. New Zealand Journal of Ecology, 34 (3): 00-00

The presence of feral cats (Felis catus) in the braided river valleys of New Zealand poses a threat to native species such as the critically endangered black stilt (Himantopus novaezelandiae). Trapping remains the most common method to control introduced predators, but trap placement criteria have not been fully informed by advances in the understanding of the spatial ecology of the pest species. We assessed the suitability of Global Positioning System (GPS) tags to study the spatial behaviour of feral cats in New Zealand braided rivers. We tagged and tracked five individual adults, one female and four males. Tracking periods varied from 3 to 18 days at a fix rate of one location every 15 min. This rate was considered an adequate trade-off between battery limitations and the opportunity to approximate the continuous displacement path of a cat for a representative number of days. Individual home range size estimates (100% Minimum Convex Polygon, MCP) varied from 178 to 2486 ha. For four of the six cats incremental analysis revealed that at least 460 locations are required to calculate a home range using MCP. Habitat selection analysis showed significant differences among individuals tending to select ‘Mature riverbed’ habitats. Trapping effort should be focused on this habitat. Movements and distances travelled revealed that cats move mainly between mid-afternoon (1500 hours) and early morning (0300 hours). This study showed that GPS telemetry provides a powerful method to study feral cat movements in open landscapes in New Zealand.