Les hommes ont oublié cette vérité. Mais tu ne dois pas l'oublier, dit le renard. Tu deviens responsable pour toujours de ce que tu as apprivoisé.
Le Petit Prince, chap. 21

Tuesday, 31 March 2015

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.

Colony cats' parasites in an urban area in N Italy

Zanzani, S. A., Gazzonis, A., Magistrelli, S., & Manfredi, M. T. (2015). Pulmonary and intestinal parasites in colony cats as markers for biodiversity in an urban area. Urban Ecosystems, 1-11.

Urban colony cats are part of the vertebrate community in urban ecosystems in the metropolitan area of Milan, Lombardy, Italy (45° 27′ N, 9° 11′ E) their management is mainly based on the practice of their capture/sterilization/release. Aims of this research, performed from May 2013 to March 2014, were to determine the qualitative and quantitative composition of endoparasitic infections in urban colony cats, the spatial distribution of infected colony cats, and the likelihood that parasites of colony cats act as markers for biodiversity in an urban ecosystem. Pulmonary and intestinal parasites were detected in feces of 35.92 % of colony cats specifically, four intestinal nematodes (Toxocara cati, Toxascaris leonina, Ancylostomatidae and Trichuris vulpis), two intestinal cestodes (Dipylidium caninum and Spirometra sp.), one intestinal protozoan (Cystoisospora sp.) and one pulmonary nematode (Aelurostrongylus abstrusus) were isolated. Infected and non-infected colony cats did not show any statistically significant difference as to their distances from the center of the city. However, in urban colony cats infected and non-infected by A. abstrusus, in cats infected and non-infected by parasites presenting an indirect life cycle (ILC) and in cats with or without multiparasitic infections were detected appreciable differences in their distances from the edges of the nearest green urban areas having different sizes. For A. abstrusus, parasites with an indirect life cycle (ILC), and multiparasitic infections, significant differences in distance from green urban areas were detected for infected vs. non-infected urban colony cats particularly, shorter distances for infected cats were observed, suggesting that cats living closer to green urban areas with higher biodiversity were more likely to be infected.

Wednesday, 25 March 2015

Pet cat home-range sizes may be underestimates in some studies

Coughlin, C. E., & van Heezik, Y. (2015). Weighed down by science: do collar-mounted devices affect domestic cat behaviour and movement?. Wildlife Research, 41(7), 606-614.

Context: Animals carrying tracking and logging devices are subject to a range of instrument effects that negatively affect survival, reproduction and behaviour. The common recommendation is that device weight should not exceed 5% body mass (BM) for terrestrial species; however, this rule-of-thumb has little empirical basis. Modelling indicates that devices weighing less than 3% BM may still have impacts. Several studies have used telemetry and data loggers on domestic cats (Felis catus) with instruments ranging in weight from 30 g to 125 g, but there has been no quantitative evaluation of instrument effects. In addition, inexpensive GPS tags such as iGotU are increasingly being used to track domestic cats, but often with little acknowledgement of habitat-related location error.

Aims: We evaluated the impact of wearing devices of different weights on domestic cat movements, and quantified location error across typical suburban habitats.

Methods: We recorded movements of cats wearing three different GPS collar weights for a week at a time: light, 30 g (<1% BM); medium, 80 g (~2% BM); and heavy, 130 g (~3% BM). Location error (LE) and fix success rates (FSR) were compared between backyard habitats and up- or downward orientation of the GPS tags on collars.

Key results: Home-range size and distance travelled from home were smaller when cats wore the heaviest collar. LE was lower and FSR higher for GPS tags with direct-line-of-sight to satellites (e.g. on lawns), but there was no difference between tags placed in dense vegetation (hedges) or more open vegetation (trees), or tags oriented up or down.

Conclusions: Collars carrying instruments on cats should be no more than 2% BM (medium-weight collar). LE was large relative to typical urban habitat size, indicating that misclassification of locations into habitats could easily occur in habitat-selection studies.

Implications: Some published accounts of cat home-range sizes may be underestimates, resulting in underestimates of the extent of impacts on prey species. Habitat-use studies should acknowledge the error associated with GPS tags and incorporate it into analyses using techniques such as Brownian Bridges.

Monday, 23 March 2015

Activity and exploration range of house cats in rural areas of central Poland

Goszczynski, J., Krauze, D., and Gryz, J. (2009). Activity and exploration range of house cats in rural areas of central Poland. Folia Zoologica 58, 363–371.  

Domestic cats are the most numerous predators in Poland. They are commonly kept at farms but hardly controlled, so penetrate freely wide range of habitats. The work aimed at determining the range of greatest impact of cats by identifying patterns of their activity and area searching, over daily, monthly and annual cycles. The density index, estimated from transect counts, performed along standard routes, proved to be dependent on temperature, precipitation and time of the day. In spring and summer, cats presented a two-peaked activity pattern, while in cold seasons it was more stable throughout the day. In warm months cats were registered at a further distance from the buildings than in colder ones. The animals were much less active when rain was falling. Cats’ responses on noticing an observer showed that the further they were from the edges of settlements the more timid and cautious they became. The results showed that the potential pressure that cats may exert on their prey is the biggest around dawn and dusk and in summer. During a daytime it is confined to the immediate vicinity of build-up areas.

Sunday, 8 March 2015

Cats killing endangered night parrot

The latest twist in the rather secret story of the Night Parrot (Pezoporus occidentalis) is that a cat-killed individual has been found in an area of arid spinifex country SW of Winton, in W Queensland, close to where John Young photographed the species for the first time in May 2013.
Apparently, according to Queensland government sources, professional marksmen have been employed by a private conservation company to patrol the area at night with spotlights, shooting feral cats (Felis catus) on sight. The programme is funded by mining company Fortescue Metals, whose involvement dates back to the reported discovery of Night Parrots in a mineral exploration area in Western Australia in 2005. However, government agencies have been kept in the dark concerning the whereabouts of Night Parrots in Queensland, and the sites where the species occur are on a privately leased grazing property. Feral cats have long been implicated in the decline of this once widespread species: in 1892, it was reported that ‘numerous’ parrots were killed by cats near Alice Springs. Some observers have noted increases in feral cat populations in recent years in parts of inland Australia. The region around Winton where the parrots occur has been drought-afflicted for several years.
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