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
Showing posts with label 2002. Show all posts
Showing posts with label 2002. Show all posts

Monday, 13 June 2016

Distemper outbreak and its effect on African wild dog conservation

Sunday, 1 May 2016

FeLV and FIV in free-roeaming cats

Lee, I.T., Levy, J.K., Gorman, S.P., Crawford, P.C. and Slater, M.R.2002. Prevalence of feline leukemia virus infection and serum antibodies against feline immunodeficiency virus in un-owned free-roaming cats. Journal of the American Veterinary Medical Association, 220: 620–622.

Objective—To determine prevalence of FeLV infection and serum antibodies against feline immunodeficiency virus (FIV) in unowned free-roaming cats.
Design—Cross-sectional serologic survey.
Animals—733 unowned free-roaming cats in Raleigh, NC, and 1,143 unowned free-roaming cats in
Gainesville, Fla.
Results—In Raleigh, overall prevalence of FeLV infection was 5.3%, and overall seroprevalence for FIV was 2.3%. In Gainesville, overall prevalence of FeLV infection was 3.7%, and overall seroprevalence for FIV was 4.3%. Overall, FeLV prevalence was 4.3%, and seroprevalence for FIV was 3.5%. Prevalence of FeLV infection was not significantly different between males (4.9%) and females (3.8%), although seroprevalence for FIV was significantly higher in male cats (6.3%) than in female cats (1.5%).
Conclusions and Clinical Relevance—Prevalence of FeLV infection and seroprevalence for FIV in unowned free-roaming cats in Raleigh and Gainesville are similar to prevalence rates reported for owned cats in the United States. Male cats are at increased risk for exposure to FIV, compared with female cats.

Wednesday, 17 December 2014

Comparison of managed and unmanaged wedge-tailed shearwater colonies: Effects of predation

Smith, D. G., Polhemus, J. T., & VanderWerf, E. A. (2002). Comparison of managed and unmanaged wedge-tailed shearwater colonies on O'ahu: Effects of predation. Pacific Science, 56(4), 451-457.

On O‘ahu, Wedge-tailed Shearwaters (Puffinus pacificus) and other seabirds nest primarily on small offshore islets, but fossil evidence shows that many seabirds formerly bred on O‘ahu itself. Predation by introduced mammals is suspected to be the primary factor preventing shearwaters and other seabirds from reestablishing large nesting colonies on O‘ahu. We investigated the effects of predation on Wedge-tailed Shearwaters by comparing three small unmanaged colonies at Mālaekahana State Recreation Area on O‘ahu, where feral cats are fed by the public, with a large managed colony at nearby Moku‘auia Island State Seabird Sanctuary, where predators are absent. During three visits on 19 April, 16 June, and 23 October 2000, we located 69 occupied burrows in three colonies at Mālaekahana and 85 occupied burrows in four monitoring plots at Moku‘auia. Many more nests produced chicks at Moku‘auia (62%) than at Mālaekahana (20%). Among plots at Ma¯laekahana, reproductive success was lowest (zero) at the colony closest to the cat feeding site. In addition, 44 adult shearwater carcasses were found at Mālaekahana near the cat feeding site. Predation, most likely by cats attracted to supplemental food, had a devastating impact on shearwaters at Mālaekahana. At one colony there was complete reproductive failure and almost all adults were killed. Populations of long-lived species like seabirds are sensitive to adult mortality, and Ma¯laekahana may act as a sink, draining birds away from other areas.

Thursday, 2 October 2014

TNR program for feral cats on Prince Edward Is.

Gibson, K. L., Keizer, K., & Golding, C. (2002). A trap, neuter, and release program for feral cats on Prince Edward Island. The Canadian Veterinary Journal, 43(9), 695.

A new program to address the feral cat population on Prince Edward Island was undertaken during the spring and summer of 2001. Feral cats from specific geographic areas were trapped, sedated, and tested for feline leukemia virus and feline immunodeficiency virus. Healthy cats were neutered, dewormed, vaccinated, tattooed, and released to their area of origin. A total of 185 cats and kittens were trapped and tested during a 14-week period; 158 cats and kittens as young as 6 weeks of age were neutered and released. Twenty-three adult cats were positive for feline leukemia virus, feline immunodeficiency virus, or both, and were euthanized.

Saturday, 20 September 2014

Cat population density in a sub-Antarctic island

Say, L., Gaillard, J. M., & Pontier, D. (2002). Spatio-temporal variation in cat population density in a sub-Antarctic environment. Polar Biology, 25(2), 90-95.

We used the walked-line transect method for estimating the density of cats and coefficients of variation of density estimates in 4 contrasted sites on the main island of Îles Kerguelen between 1998 and 2000. Density estimates varied from 0.44±0.15 cats per km2 to 2.42±0.23 cats per km2  according to site and period. Coefficient of variation of density estimates ranged from 11.92% to 34.76%. The line transect method was, therefore, an efficient method for monitoring the density of the cat population in a sub-Antarctic environment characterised by short vegetation. Our results suggest that cat population size at the main island of Îles Kerguelen (the total number of cats expected is around 7,000) is much lower than previously thought.

Friday, 15 August 2014

Cat eradication on Hermite island


Feral cats (Felis catus) and black rats (Rattus rattus) became established on the Montebello Islands, an archipelago of about 100 islands, islets and rocks off the Pilbara coast of Western Australia, during the late 19th century. They were probably introduced from pearling vessels. The largest island in the group is Hermite at 1020 ha. Three species of native mammals and two of birds became extinct well before the British used the islands for testing nuclear weapons in the 1950s. Montebello Renewal (part of the ‘Western Shield’ fauna recovery programme) aims to eradicate feral animals from, and reintroduce and introduce threatened animals to, the Montebellos. Rats occurred on almost every island and islet when eradication was attempted in 1996. In 1999 small numbers of rats were detected on Hermite and two adjacent islands and work is under way to eliminate them. Feral cats occurred on several islands at various times, but by 1995 were naturally restricted to Hermite. Feral cat eradication took place in 1999 and comprised two stages – aerial baiting and trapping. Aerial baiting utilised recently developed kangaroo meat sausage baits with flavour enhancers and the toxin 1080. About 1100 baits were dropped by hand from a helicopter. Hermite Island has two main soil types – sand and limestone. Aerial baiting primarily targeted sandy soils. Four cats, all females, remained after baiting. These were trapped using Victor ‘softcatch’® traps set either in association with phonic and odour lures or set in narrow runways. Eradication was achieved over a six-week period. Searches for evidence of cat activity in 2000 confirmed that cats had been eradicated.










The eradication of alien mammals from five offshore islands, Mauritius

Bell, B. D. (2002). The eradication of alien mammals from five offshore islands, Mauritius, Indian Ocean. In Veitch, C. R., & Clout, M. N. (2002). Turning the Tide: The Eradication of Invasive Species: Proceedings of the International Conference on Eradication of Island Invasives,[University of Auckland, 19 to 23 February 2001] (No. 27). IUCN 40-45.

Following the removal of rabbits from Round Island in 1979 and the publication of a management plan in 1989, the Mauritius Government contracted Wildlife Management International Limited in 1993 to fulfil one of the plan’s recommendations to survey the offshore islands of Mauritius and Rodrigues and to prepare an offshore islands management plan. This plan made a number of recommendations and priorities in relation to the removal of alien species. In 1995 work on the priorities began with the removal of Norway rats (Rattus norvegicus) and hares (Lepus nigricollis) from Gunner’s Quoin, ship rats (R. rattus) from Gabriel Island and mice (Mus musculus) from Ile Cocos and Ile aux Sables. In 1998 cats (Felis catus), ship rats and mice were removed from Flat Island and rabbits (Oryctolagus sp.), which had been illegally released following the earlier eradications, from Gunner’s Quoin. These programmes were hand-laid operations. In all cases the main bait was grain-based pellets containing 0.02gm/kg brodifacoum. The bait was set out on at least half of the maximum grid recommended for the rodent species targeted. The exception was cats, which were trapped in leg-hold traps. Plans are being considered for the re-introduction of reptiles and birds. Some planting of native trees has begun. This paper covers the eradication sector of the management plan

Introduced mammal eradications for nature conservation on Western Australian islands: a review

Burbidge, A. A., & Morris, K. D. (2002). Introduced mammal eradications for nature conservation on Western Australian islands: a review. In Veitch, C. R., & Clout, M. N. (2002). Turning the Tide: The Eradication of Invasive Species: Proceedings of the International Conference on Eradication of Island Invasives,[University of Auckland, 19 to 23 February 2001] (No. 27). IUCN, 64-70.

There are about 3400 islands off the Western Australian coast, many of which have high nature conservation
values. Eleven species of introduced mammals occur or occurred on 124 islands, including three domestic animals (horse, camel and sheep) that have not become feral. In addition, Aborigines introduced dingoes to at least four islands before European settlement. Six exotic mammals (red fox, feral cat, goat, rabbit, black rat and house mouse) have now been eradicated from more than 45 islands in a series of projects since the 1960s. Most effort has been directed at black rats with more than 31 islands now clear of this species. Pindone, vacuum-impregnated into oats, was used until the 1990s, when bran pellets with brodifacoum were used in the Montebello Islands. Rabbits have been eradicated using carrots soaked in sodium monofluoroacetate (1080), red foxes with dried meat baits impregnated with 1080 and cats with a combination of baiting and trapping. After a period of 20 years of ground shooting, goats were finally eradicated from Bernier Island using an experienced shooter operating from a helicopter. The house mouse has been eradicated from Barrow Island four times after introductions in food and equipment, and from Varanus and adjacent islands after introduction in food containers. Both islands are utilised by the petroleum industry. Difficulties and how they were overcome, and future eradication priorities, are discussed.

Alien mammal eradication and quarantine on inhabited islands in the Seychelles

Mertori, D., Climo, G., Laboudallon, V., Robert, S., & Mander, C. (2002). Alien mammal eradication and quarantine on inhabited islands in the Seychelles. In Veitch, C. R., & Clout, M. N. (2002). Turning the Tide: The Eradication of Invasive Species: Proceedings of the International Conference on Eradication of Island Invasives,[University of Auckland, 19 to 23 February 2001] (No. 27). IUCN, 182-198.

During the period 1996-2000, eradication of five introduced mammal species (feral cat (Felis catus), rabbit (Oryctolagus cuniculus), ship rat (Rattus rattus), Norway rat (R. norvegicus) and house mouse (Mus domesticus)), was attempted on four inhabited islands, including three resort islands, ranging in size from 101–286 ha in the Seychelles group, Indian Ocean. Objectives were to avert extinctions of, and restore urgently-needed habitat for, localised threatened endemic animals and to facilitate ecological restoration in line with a national biodiversity strategy. Local political, economic and biological constraints meant that adaptations were necessary to traditional poisoning and trapping methods and regimes. Furthermore, since no rat-free island was available to which native animals at risk from primary and/or secondary poisoning might be transferred, it was necessary to maintain approx. 590 individuals of three threatened animal species in captivity for the three months of the eradication programme. Strategies and techniques developed, and some of the many challenges encountered in conducting eradication and quarantine programmes on inhabited, tropical islands are outlined, together with progress to date. One island (Bird) has been maintained free of rats and rabbits since their eradication in 1996. Two others (Denis and Curieuse) are now free of feral cats but have been recolonised by Rattus rattus since eradication attempts in 2000. The fourth (Frégate), was successfully cleared of R. norvegicus and mice in 2000, in time to avert extinctions of localised threatened endemic animals. These positive results will, we hope, inspire similar effort on other inhabited islands with high biological values or potential.

Cat eradication and the restoration of endangered iguanas on Long Cay


Endangered Turks and Caicos rock iguanas (Cyclura carinata) are being displaced on Big Ambergris Cay
by an expansive development project. We chose Long Cay, Caicos Bank, as a relocation site for some iguanas because it: (1) is a large (111 ha), uninhabited, protected reserve, (2) previously supported iguanas but did not have a current population, (3) could support thousands of iguanas, and (4) had no native mammals, few scavenging birds, and no nesting colonies of scavengers. There was a small population of feral cats, well-known iguana predators. To restore the island, we conducted an intensive cat poisoning campaign using sodium monofluoroacetate (1080), in July 1999. In November 1999, a test-group of 25 iguanas was taken from Big Ambergris Cay to Long Cay. Since their successful establishment we have relocated more than 400. The first hatchlings were confirmed in January 2001. Occasional trapping may be necessary to maintain Long Cay free of cats. We have begun patrols and courtesy visits to vessels cruising the area, installed informative and cautionary signs, and produced public service announcements for TV to reinforce the importance of keeping domestic animals away from uninhabited islands.

Removing cats from islands in NW Mexico

Wood, B., Tershy, B. R., Hermosillo, M. A., Donlan, C. J., Sanchez, J. A., Keitt, B. S., Croll, D.A. Howald, G.R. & Biavaschi, N. (2002). Removing cats from islands in north-west Mexico. In Veitch, C. R., & Clout, M. N. (2002). Turning the Tide: The Eradication of Invasive Species: Proceedings of the International Conference on Eradication of Island Invasives,[University of Auckland, 19 to 23 February 2001] (No. 27). IUCN, 374-380.


Feral cats have been associated with extinctions of endemic island species throughout the world. Removing cats from islands is an effective way to protect biodiversity, but compared to other invasive alien mammals, cats are difficult to eradicate. Here we describe the techniques we used to eradicate cats from 15 islands in north-west Mexico between <1 and 43 km2  These eradication techniques were developed and refined on small islands (<1 km2) and then adopted successfully on larger islands (1– 43 km2 . Experienced hunters and trappers, and high quality hunting dogs were critical for successful cat eradication. The most effective technique was trapping and the most critical components of trapping were trap design and placement.

Tuesday, 15 April 2014

Eurasian origin of American dogs

Leonard, J. A., Wayne, R. K., Wheeler, J., Valadez, R., Guillén, S., & Vila, C. (2002). Ancient DNA evidence for Old World origin of New World dogs. Science,298 (5598), 1613-1616.

Mitochondrial DNA sequences isolated from ancient dog remains from Latin America and Alaska showed that native American dogs originated from multiple Old World lineages of dogs that accompanied late Pleistocene humans across the Bering Strait. One clade of dog sequences was unique to the New World, which is consistent with a period of geographic isolation. This unique clade was absent from a large sample of modern dogs, which implies that European colonists systematically discouraged the breeding of native American dogs.

Wednesday, 1 January 2014

Social and genetic analysis of a population of free-living cats at a waste disposal site

Denny, E., Yakovlevich, P., Eldridge, M. D., & Dickman, C. (2002). Social and genetic analysis of a population of free-living cats (Felis catus L.) exploiting a resource-rich habitat. Wildlife Research, 29(4), 405-413.

Free-living cats (Felis catus L.) exploiting a waste-disposal site in rural Australia were studied for two years to investigate population structure and dynamics, and the relatedness of constituent individuals. The density of the population was equivalent to 700–750 cats  km-2  the sex ratio was heavily skewed towards males, breeding occurred from July to April, and kitten survival rates were low. A combination of observational data, biometrics and microsatellite loci analyses was used to assess the relatedness of individuals in the population; these methods yielded highly congruent results. Thus, a female kin-group of three was identified, there was no female immigration, the average relatedness amongst the population was high and there was no indication of male dominance. The results indicate that cats at the site formed a tightly structured group, rather than an ad hoc collection of individuals. The stable, resource-rich habitat of waste-disposal sites may generally support high densities of group-forming cats in rural Australia, and pose broad-scale but previously unrecognised problems for effective management of free-living cats.

Saturday, 9 November 2013

Cats, the main predator of ground nesting birds in the Upper Waitaki Basin


We used video cameras over 5 years to quantify causes of mortality at 172 nests of three species of ground-nesting birds that nest on braided riverbeds of the Upper Waitaki Basin, South Island, New Zealand. The species were banded dotterels Charadrius bicinctus (n=114), black stilts Himantopus novaezelandiae (n=23), and black-fronted terns Sterna albostriata (n=35). Of 77 recorded lethal events (excluding four desertions caused by us), 66 involved deaths of only eggs, and 11 involved deaths of adults and/or chicks, and/or eggs. The main predators were cats Felis catus, hedgehogs Erinaceus europaeus, and ferrets Mustela furo, which were responsible for 43, 20, and 18% of lethal events, respectively. Cats were the only predator species to take adult birds. We recorded only two avian predations: a harrier Circus approximans took a chick and a hatching egg from one nest, and an Australian magpie Gymnorhina tibicen ate chicks at one nest. Other causes of mortality were incubating adult birds, floods, and sheep Ovis aries. Each accounted for <4% of lethal events. Ninety percent of visits (151 of 168) by predators or potential predators happened between sunset and sunrise. We found no evidence that video cameras or infra-red lighting influenced predation rates during 2 years of testing for such effects.

Sunday, 20 October 2013

Two examples of cat colony management in Texas and in Florida

Hughes, K. L., & Slater, M. R. (2002). Implementation of a feral cat management program on a university campus. Journal of Applied Animal Welfare Science, 5(1), 15-28.

In August 1998, Texas A&M University implemented on campus a trap-test-vaccinate-alter-return-monitor (TTVARM) program to manage the feral cat population. TTVARM is an internationally recognized term for trapping and neutering programs aimed at management of feral cat populations. In this article we summarize results of the program for the period August 1998 to July 2000. In surgery laboratories, senior veterinary students examined cats that were humanely trapped once a month and tested them for feline leukemia and feline immunodeficiency virus infections, vaccinated, and surgically neutered them. They euthanized cats testing positive for either infectious disease. Volunteers provided food and observed the cats that were returned to their capture sites on campus and maintained in managed colonies. The program placed kittens and tame cats for adoption; cats totaled 158. Of the majority of 158 captured cats, there were less kittens caught in Year 2 than in Year 1. The proportion of tame cats trapped was significantly greater in Year 2 than in Year 1. The prevalence found for feline leukemia and feline immunodeficiency virus ELISA test positives was 5.8% and 6.5%, respectively. Following surgery, 101 cats returned to campus. The project recaptured, retested, and revaccinated more than one-fourth of the cats due for their annual vaccinations. The program placed 32 kittens, juveniles, and tame adults for adoption. The number of cat complaints received by the university's pest control service decreased from Year 1 to Year 2.

Hughes, K. L., Slater, M. R., & Haller, L. (2002). The effects of implementing a feral cat spay/neuter program in a Florida county animal control service. Journal of Applied Animal Welfare Science, 5(4), 285-298.

In 1995, a county animal control service implemented a feral cat sterilization program with the goal of reducing the number of healthy cats euthanized, complaints, and the county's costs. Theservice collected data from a 6-year period both before and after the program's implementation. The service totaled the numbers of both cat and dog impoundments, surgeries, adoptions, euthanasias, and complaints for each year; standardized both sets of numbers on a per- 10,000-person basis to compare trends between dogs and cats; and calculated estimated costs for neutering versus impounding and euthanizing the feral cats. Changing from a policy of euthanasia of feral cats to support for trap-neuter-return did not result in an increase in the number of complaints or cat impoundments. The percentage of impounded cats euthanized decreased between the periods before and after the program began, and the percentage adopted increased. The ratio of complaints to impounds decreased between the 2 periods, and the ratio of surgeries to impounds increased. Impoundments of cats were relatively steady in spite of the continually increasing human population. Euthanasias decreased for both cats and dogs since 1997. Since 1996, complaints decreased for both. Surgeries for both cats and dogs increased over the 12 years. Adoptions for cats and dogs increased greatly in fiscal year 1998/1999.

Friday, 18 October 2013

Introduction and spread of cats in Australia

Abbott, I. (2002). Origin and spread of the cat, Felis catus, on mainland Australia, with a discussion of the magnitude of its early impact on native fauna.Wildlife Research, 29(1), 51-74.

A comprehensive search of historical sources found no evidence that the cat, Felis catus, was present on mainland Australia prior to settlement by Europeans. Nor were records of cats found in journals of expeditions of exploration beyond settled areas, undertaken in the period 1788–1883. Cats did not occupy Australia from the earliest point of entry (Sydney, 1788), but instead diffused and were spread from multiple coastal introductions in the period 1824–86. By 1890 nearly all of the continent had been colonised. This new chronology for the feline colonisation of Australia necessitates a re-appraisal of the early impact of the cat on native mammal and bird species. The evidence for early impacts of cats causing major and widespread declines in native fauna is considered tenuous and unconvincing.

Abbott, I. (2008). The spread of the cat, Felis catus, in Australia: re-examination of the current conceptual model with additional information.Conservation Science Western Australia, 7(1), 1-17.

This paper is an update of Abbott, I (2002) Origin and spread of the cat, Felis catus, on mainland Australia, with a discussion of the magnitude of its early impact on native fauna. Wildlife Research 29, 51–74. An additional 33 journals of expeditions of exploration or excursions beyond settled areas before 1895 were located, and as expected from the current conceptual model, none of these recorded cats. These accounts of travel through country as yet unsettled or sparsely settled by Europeans necessitate only one small modification (relating to north-east Queensland) to the conceptual model presented previously. In addition, nearly 150 new records of cats were located in other parts of Australia, and all are consistent with the chronology of spread hypothesized in the previous paper. For Tasmania, following their introduction in 1804, cats were first recorded there as feral in the 1840s. Incidental records were found indicating that in parts of Australia the spread of the cat was assisted by their release in regions experiencing their first outbreaks of rabbits, by flood-linked irruptions of the long-haired rat (Rattus villosissimus), and by their release to control rodents destroying sugar cane plantations in northern Queensland. Feral cats of large size were first detected in various regions of Australia some 10–30 years after local settlement.

Thursday, 3 October 2013

Mammal extinctions on Australian islands due mainly to cats

Burbidge, A. A., & Manly, B. F. (2002). Mammal extinctions on Australian islands: causes and conservation implications. Journal of Biogeography, 29(4), 465-473.

Aim

Data on Australian landbridge islands were analysed to seek relationships between the extinction of mammals on islands and a number of variables related to the islands, the native mammal species that occur on them and the presence or absence of exotic mammalian predators. The data base included attributes of the mammals (mean adult body weight, diet and shelter habitat) and of the islands [area, rainfall, presence/absence of significant areas of rockpile habitat, presence/absence of European red fox Vulpes vulpes Linnaeus, 1758, feral cat Felis catus Linnaeus, 1758, and rats Rattus rattus (Linnaeus, 1758) and R. exulans (Peale, 1848)].

Methods

Statistical analysis of the 388 cases where a Critical Weight Range (CWR) mammal is extant and the forty-one cases where a CWR mammal is extinct was conducted using logistic regression to model the probability of extinction as a function of the island and mammal variables.

Results

Foxes and cats are correlated with CWR mammal extinctions, but cats are associated with extinctions particularly on more arid islands. Extinctions are more likely on islands with an absence of significant areas of rockpile habitat and where the native mammal is restricted to the ground's surface, and is relatively large.

Conclusions

An association between the presence of cats and native mammal extinctions has not previously been demonstrated for Australian islands. The introduction of exotic predators to Australian islands with native mammal species should be avoided and should any of these predators establish all means should be employed to eradicate them. For Australian continental islands the introduction of exotic predators, not habitat clearance, has been the major factor in extinctions.

Sunday, 22 September 2013

Feral cat home range and habitat selection in central Australia

Edwards, G. P., De Preu, N., Shakeshaft, B. J., Crealy, I. V., & Paltridge, R. M. (2001). Home range and movements of male feral cats (Felis catus) in a semiarid woodland environment in central Australia. Austral Ecology, 26(1), 93-101.

There is a paucity of data on the movement patterns of feral cats in Australia. Such data can be used to refine control strategies and improve track-based methods of monitoring populations of feral cats. In this study the home ranges and movements of male feral cats were examined over 3.5 years in a semiarid woodland environment in central Australia. Two home range estimators were used in the examination: (i) minimum convex polygon (MCP); and (ii) fixed kernel. The most widely used method of estimating home range in feral cats is MCP, while the fixed kernel method can be used to identify core areas within a home range. On the basis of the MCP method, the long-term home ranges of feral cats in central Australia were much larger than those recorded elsewhere (mean, 2210.5 ha). Twenty-four hour home ranges were much smaller (mean, 249.7 ha) and feral cats periodically shifted their 24 h ranges within the bounds of their long-term home ranges. Core area analysis indicated marked heterogeneity of space use by male feral cats. Several instances where feral cats moved large distances (up to 34 km) were recorded. These long distance movements may have been caused by nutritional stress. Using data from the literature, it is shown that prey availability is a primary determinant of long-term home range size in feral cats. The relevance of the results to the design of management strategies for feral cats in central Australia is also discussed.

Edwards, G. P., Preu, N., Crealy, I. V., & Shakeshaft, B. J. (2002). Habitat selection by feral cats and dingoes in a semi‐arid woodland environment in central Australia. Austral Ecology, 27(1), 26-31.

Habitat use by feral cats and dingoes was examined within a heterogeneous semi-arid woodland site in central Australia over 2 years. Density estimates of feral cats based on tracks were higher in mulga habitat than in open habitat. Isodar analysis implied that this pattern of habitat use by feral cats was consistent with the consumer-resource model of density-dependent habitat selection, which is an ideal free solution. The reason why mulga supported higher densities of feral cats was unclear. Foraging success of feral cats may be higher in the mulga because the stalk and ambush hunting tactics typically employed by felids are well suited to dense cover. Mulga may also have offered feral cats more protection from dingo predation. Dingo activity was distributed uniformly across habitats. The dingo isodar was statistically non-significant, suggesting that habitat selection by dingoes was independent of density.


Sunday, 4 August 2013

Cats favoured by habitat fragmentation and isolation

Crooks, K.R. 2002. Relative sensitivities of mammalian carnivores to habitat fragmentation. Conservation Biology 16(2): 488-502.

I examined the effects of habitat fragmentation on the distribution and abundance of mammalian carnivores in coastal southern California and tested the prediction that responses to fragmentation varied with the body size of carnivore species. I conducted track surveys for nine native and two exotic carnivore species in 29 urban habitat fragments and 10 control sites. Fragment area and isolation were the two strongest landscape descriptors of predator distribution and abundance. Six species were sensitive to fragmentation, generally disappearing as habitat patches became smaller and more isolated; three species were enhanced by fragmentation, with increased abundance in highly fragmented sites; and two species were tolerant of fragmentation, with little to no effect of landscape variables on their distribution and abundance. Within urban habitat fragments, the carnivore visitation rate increased at sites with more exotic cover and closer to the urban edge, a pattern driven largely by the increased abundance of fragmentation-enhanced carnivores at edge sites. Finally, body size, in conjunction with other ecological characteristics, partially accounted for the heterogeneity in responses to fragmentation among carnivore species. These differential sensitivities are useful criteria for choosing appropriate focal species for ecological research and conservation planning, a choice that depends on the scale of fragmentation in a region and the commensurate responses of carnivore populations at that scale.

___________________

Examiné los efectos de la fragmentación del hábitat sobre la distribución y abundancia de mamíferos carnívoros en la costa del sur de California y evalué la predicción de que las respuestas a la fragmentación variaban con el tamaño corporal de carnívoros. Se realizaron muestreos de huellas para nueve especies nativas y dos exóticas en 29 fragmentos de hábitat urbano y 10 sitios control. El área fragmentada y su aislamiento fueron los dos principales descriptores de la distribución y abundancia de depredadores. Seis especies fueron sensibles a la fragmentación, generalmente las especies desaparecían conforme los fragmentos eran más pequeños y aislados, tres especies fueron favorecidas por la fragmentación, con incremento en su abundancia en sitios altamente fragmentados, y dos especies fueron tolerantes a la fragmentación con poco o ningún efecto de las variables del paisaje sobre su distribución y abundancia. Dentro de los fragmentos de hábitat urbano, las tasas de presencia de carnívoros incrementaron en sitios con mayor cobertura exótica y cercanos al borde urbano, un patrón dirigido principalmente por el incremento en la abundancia de carnívoros favorecidos por la fragmentación en el borde de los sitios. Finalmente, el tamaño corporal, conjuntamente con otras características ecológicas, fueron parcialmente responsables de la heterogeneidad en respuestas a la fragmentación entre especies de carnívoros. Estas sensibilidades diferenciales son un criterio útil para seleccionar especies focales apropiadas para investigaciones ecológicas y la planeación de la conservación, una selección que depende de la escala de fragmentación en una región y de las respuestas apropiadas de las poblaciones de carnívoros a esa escala.
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