Pathogens from domestic cat on Iberian lynx

Meli M., Cattori V., Martínez F., López G., Vargas A., Simón M.A., Zorrilla I., Muñoz A., Palomares F., López-Bao J.V., Pastor J., Tandon R., Willi B., Hofmann-Lehmann R. & Lutz H. 2009. Feline Leukemia Virus and Other Pathogens as Important Threats to the Survival of the Critically Endangered Iberian Lynx (Lynx pardinus). PLoS ONE, 4(3): e4744

Background

The Iberian lynx (Lynx pardinus) is considered the most endangered felid species in the world. In order to save this species, the Spanish authorities implemented a captive breeding program recruiting lynxes from the wild. In this context, a retrospective survey on prevalence of selected feline pathogens in free-ranging lynxes was initiated.

Methodology/ Principal Findings

We systematically analyzed the prevalence and importance of seven viral, one protozoan (Cytauxzoon felis), and several bacterial (e.g., hemotropic mycoplasma) infections in 77 of approximately 200 remaining free-ranging Iberian lynxes of the Doñana and Sierra Morena areas, in Southern Spain, between 2003 and 2007. With the exception of feline immunodeficiency virus (FIV), evidence of infection by all tested feline pathogens was found in Iberian lynxes. Fourteen lynxes were feline leukemia virus (FeLV) provirus-positive; eleven of these were antigenemic (FeLV p27 positive). All 14 animals tested negative for other viral infections. During a six-month period in 2007, six of the provirus-positive antigenemic lynxes died. Infection with FeLV but not with other infectious agents was associated with mortality (p<0.001). Sequencing of the FeLV surface glycoprotein gene revealed a common origin for ten of the eleven samples. The ten sequences were closely related to FeLV-A/61E, originally isolated from cats in the USA. Endogenous FeLV sequences were not detected.

Conclusions/Significance

It was concluded that the FeLV infection most likely originated from domestic cats invading the lynx's habitats. Data available regarding the time frame, co-infections, and outcome of FeLV-infections suggest that, in contrast to the domestic cat, the FeLV strain affecting the lynxes in 2007 is highly virulent to this species. Our data argue strongly for vaccination of lynxes and domestic cats in and around lynx's habitats in order to prevent further spread of the virus as well as reduction the domestic cat population if the lynx population is to be maintained.

First detection of FeLV on Iberian lynx

Luaces I, Doménech A, García-Montijano M, Collado VM, Sánchez C, Tejerizo JG, Glaka M, Fernández P & Gómez-Lucía E. 2008. Detection of Feline Leukemia virus in the endangered Iberian lynx (Lynx pardinus). Journal of Veterinary Diagnostic Investigation, 20: 381-385

Feline retroviruses are rarely reported in lynx species. Twenty-one Iberian lynx (Lynx pardinus) blood and tissue samples collected from Doñana National Park and Los Villares (Sierra Morena) in southern Spain during 1993–2003 were analyzed by polymerase chain reaction to amplify nucleic acids from feline retroviruses. Six samples were positive for Feline leukemia virus (FeLV), but no samples tested positive for Feline immunodeficiency virus. The BLAST analysis indicated that 5 of the 6 sequences were closely related to FeLV strain Rickard subgroup A, whereas 1 sequence was identical to FeLV. To the authors' knowledge, this is the first report of FeLV in the endangered Iberian lynx.

FeLV and Iberian lynx

López G, López-Parra M, Fernández L, Martínez-Granados C, Martínez F, Meli ML, Gil-Sánchez JM, Viqueira N, Díaz-Portero MA, Cadenas R, Lutz H, Vargas A & Simón MA. 2009. Management measure to control a feline leukemia virus outbreak in the endangered Iberian lynx. Animal Conservation, 12: 173-182

The feline leukemia virus (FeLV) is a retrovirus that affects domestic cats all over the world. Its pathogenic effects generally include anemia, immunosuppression or tumors. Dissemination over populations is linked to cat sociality, because the virus is transmitted by direct contact. Although the domestic cat is its common host, FeLV infection has also been described in some wild felids. In the Iberian lynx Lynx pardinus, some sporadic FeLV infection cases have been reported since 1994, but an outbreak with the involvement of several animals has never been described until now. During spring 2007, an FeLV outbreak hit the Doñana (SW Spain) population. The infection rapidly spread throughout the densest subpopulation throughout Doñana. Infected animals showed very acute anemic disease, most of them dying in o6 months. To avoid FeLV dissemination, a control program was carried out that included removal of viremic lynxes, vaccination of negative individuals and reduction of the feral cat population. The program was implemented both in Donana and in Sierra Morena populations. In Doñana, around 80% of the total lynx population and 90% of the outbreak focus subpopulation were evaluated. Seven out of the 12 infected individuals found died and two reverted to latency; the remaining viremic animals have been kept in captivity. The outbreak appears to have been successfully confined to the subpopulation where the virus appeared and no more cases have been found since August 2007. In the larger Sierra Morena population, 8% of the lynx population was surveyed. Thirtyfour uninfected Iberian lynxes were vaccinated at least once. The FeLV prevalence was found to be 27% in the Doñana population and 0% in the Sierra Morena population.

100 millions prey in five months in UK!!

Woods, M., R.A. McDonald & S. Harris. 2003. Predation of wildlife by domestic cats Felis catus in Great Britain. Mammal Review 33 (2), 174-188.

1. A questionnaire survey of the numbers of animals brought home by domestic cats Felis catus was conducted between 1 April and 31 August 1997. A total of 14 370 prey items were brought home by 986 cats living in 618 households. Mammals made up 69% of the items, birds 24%, amphibians 4%, reptiles 1%, fish <1%, invertebrates 1% and unidentified items 1%. A minimum of 44 species of wild bird, 20 species of wild mammal, four species of reptile and three species of amphibian were recorded.

2. Of a sample of 696 individual cats, 634 (91%) brought home at least one item and the back-transformed mean number of items brought home was 11.3 (95% CI 10.4–12.2). The back-transformed means and number of cats retrieving at least one item from each prey group were: 8.1 (7.4–8.9) mammals for 547 (79%) cats, 4.1 (3.8–4.5) birds for 506 (73%) cats, 2.6 (2.2–3.0) herpetofauna for 145 (21%) cats and 2.2 (1.8–2.7) other items for 98 (14%) cats. 

3. The number of birds and herpetofauna brought home per cat was significantly lower in households that provided food for birds. The number of bird species brought home was greater in households providing bird food. The number of birds and herpetofauna brought home per cat was negatively related to the age and condition of the cat. The number of mammals brought home per cat was significantly lower when cats were equipped with bells and when they were kept indoors at night. The number of herpetofauna brought home was significantly greater when cats were kept in at night.

4. Based on the proportion of cats bringing home at least one prey item and the backtransformed means, a British population of approximately 9 million cats was estimated to have brought home in the order of 92 (85–100) million prey items in the period of this survey, including 57 (52–63) million mammals, 27 (25–29) million birds and 5 (4–6) million reptiles and amphibians.

5. An experimental approach should be taken to investigate the factors found by this descriptive survey to influence the numbers of prey brought home by cats. In particular, investigation of potential management practices that could reduce the numbers of wild animals killed and brought home by cats will be useful for wildlife conservation, particularly in suburban areas.


Read more national surveys results on cat predation

Read a short review about belling effectiveness

Cats predation and winter shortages for raptor prey

George, W.G.. 1974. Domestic cats as predators and factors in winter shortages of raptor prey. The Wilson Bulletin 86(4):384-396.

The  reader  who  has  digested  my  findings  can  imagine  that  a hawk  visiting my  study  site  in  the  winters  of  1968-1971  was  more  apt  to  see a  cat  than  a rodent

A  continuous  study  of  predation  by  three  rural  cats  was  conducted  in  Union  County, southern  Illinois,  from  1  January  1968  through  31  December  1971.  The  results  established  a  basis  for  examining  the  possibility  that  cat  predation  may  result  in  depleted winter  populations  of  microtine  rodents  and  other  prey  of  Red-tailed  Hawks,  Marsh Hawks,  and  American  Kestrels. 

Although  one of  the  three  cats never  ate  prey  and  each cat  was  assured  an  ample  supply  of  daily  food  at  home,  all  captured  prey.  Their  combined  predation  removed  an annual  average  of  483.5  vertebrates  and  286.4  mammalian  fetuses  from  a  combined  home range  of  22  acres  of  field  habitat  and  three  acres  of  woods.  By  volume,  the  principal prey  were  non-adult  cottontails,  by  frequency  of  captures,  prairie  voles.  Rodents  of seven  species  constituted  81.9  percent  of  the  total  combined  diurnal-crepuscular- nocturnal  catch,  and  over  95  percent  of  the  crepuscular-nocturnal  catch. 

The  cats  obtained  92.6  percent  of  their  average  annual  diurnal  captures  between  1 March  and  30  November.  Their  hunting  sucess in  winter  was  very  poor,  probably  as a  result  of  prey  shortages that  their  own  prior  predation  may  have  helped  create.  It  is suggested  that  when  captures  of  preferred  prey  by  skillful,  experienced  cats  on  their natal  hunting  grounds  sharply  decline,  the  home  range  of  the  cats  contains  few  such prey  for rodent-seeking  hawks. 

Migración e islas / Migration and islands

Islands are important stopovers for many migrant passerines. Birds arrive exahusted and with few chances to avoid predators. When these are abundant, for instance because of being well fed by domestic waste, islands become traps for birds.

Many stray cats can also kill without a need and neglect their preys. 

(foto, Gonzalo Martínez Salcedo)

Las islas son escalas fundamentales en la migración de muchas especies de paseriformes. Las aves llegan agotadas y con pocas posibilidades de reaccionar ante los depredadores. Cuando estos alcanzan densidades importantes, por tratarse de poblaciones bien alimentadas por los restos domésticos, las islas se convierten en una trampa.

Los gatos errantes también matan sin necesidad inmediata de alimentarse y abandonan sus presas.

Effect on dogs on nightjars

Langston, R.H.W., Liley, D., Murison, G., Woodfield, E. & Clarke, R.T. (2007). What effects do walkers and dogs have on the distribution and productivity of breeding European Nightjar Caprimulgus europaeus? Ibis, 149(Suppl. 1): 10.

Several successive studies of European Nightjars Caprimulgus europaeus (hereafter, Nightjar) on the Dorset heaths demonstrated negative effects of the proximity of urban development and associated disturbance from access on foot by people and dogs. Surrogate measures of human density and settlement, including the amount of developed land around each heathland patch and the number of houses, were significantly and negatively related to the density of Nightjars (using data from the 1992 national survey) on heathland patches, regardless of patch size. These findings prompted targeted field studies, the subject of this paper, which investigated the mechanisms and effects of recreational disturbance on breeding Nightjars. Fieldwork in 2002 focused on a suite of heathland sites representing a range of access from sites closed to the public to heaths heavily used for recreation, notably by dog walkers. Studies in 2003 concentrated on the heavily used heaths. Nests which failed were significantly closer to paths, tended to be closer to the main points of access to heaths, in areas with higher footpath density, notably of high levels of use, and in more sparsely vegetated locations. The proximate cause of nest failure was most frequently egg predation. Nest cameras, deployed in 2003 in an attempt to identify the predators of eggs or chicks, recorded just one instance of predation, that of an egg by a Carrion Crow Corvus corone, and two instances of the incubating bird being flushed by a dog, once from an egg and once from a chick, neither event preventing fledging. Flushing rate of Nightjars from the nest was associated with the height of vegetation around the nest and the extent of nest cover. The studies indicate that access disturbance interacts with environmental conditions for breeding birds. Birds flush more readily from eggs, which are highly visible when exposed, especially in areas with sparse nest cover, leaving them vulnerable to predation. Although Nightjar flushing rates were observed to be low in 2003, just one event leading to predation is enough to end that nesting attempt. Management measures are recommended to minimize the effects of walkers and their dogs on Nightjars.

Canine distemper impact on African wild dogs

Alexander, K.A. & M.J. Appel. 1994. African wild dogs (Lycaon pictus) endangered by a canine distemper epizootic among domestic dogs near the Masai Mara National Reserve, Kenya. Journal of Wildlife Diseases, 30 (4): 481-485

A longitudinal study of canine distemper (CD) among domestic dogs on Malsai communal land to the north of the Masai Mara National Reserve in Kenya was conducted from 1989 to 1991. Prevalence of antibodies to CD was very low among domestic dogs in 1989 and 1990 (4%, n = 49; and 1%, n = 119, respectively) and no African wild dogs (Lycaon pictus; n = 16) collected simultaneously from the same area had detectable antibodies. Among 51 domestic dogs sampled in 1991, however, prevalence of CD antibodies rose significantly (P < 0.01) to 76%. Disease-related mortality rates among domestic dogs were estimated from 1990 to 1992; they rose significantly (P < 0.01) from 21% in 1990 to 50% in 1991 and then decreased significantly (P < 0.01) to 38% in 1992. The 1992 mortality rate remained significantly (P < 0.01) higher than that of 1990. Signs observed in clinically ill domestic dogs were consistent with CD and included listlessness, decreased appetite, bilateral serous to mucopurulent oculonasal discharge, and diarrhea. No carcasses could be retrieved for virus isolation and postmortem examination. Concurrent with this CD epizootic in domestic dogs, the known African wild dog packs in this region disappeared.

CDV impact on island foxes

Timm, S. F., L. Munson, B.A. Summers, K.A. Terio, E.J. Dubovi, C.E. Rupprecht, S. Kapil & D.K. Garcelon.  2009. A suspected canine distemper epidemic as the cause of a catastrophic decline in Santa Catalina Island foxes (Urocyon littoralis catalinae). Journal of Wildlife Diseases 45(2): 333-343.

The island fox (Urocyon littoralis catalinae) population on Santa Catalina Island, California, USA declined precipitously in 1999 with an approximate 95% reduction on their eastern range, an area representing 87% of the island. During this investigation, between October 1999 and April 2000, evidence of live foxes dramatically decreased. The only carcass recovered during the decline succumbed to a co-infection of canine distemper virus (CDV) and toxoplasmosis. Sequence analysis of the viral P gene, derived by polymerase chain reaction, indicated that the virus was closely related to CDV from a mainland USA raccoon (Procyon lotor). Nine of 10 foxes trapped in 1999–2000, on the eastern portion of the island after the decline, had serologic evidence of exposure to CDV, whereas only four of 19 foxes trapped in this region in 1998 had antibodies reactive against CDV. The confirmation of CDV in one deceased fox, evidence of exposure to CDV in east-end foxes in 1999–2000 compared to 1998, and documentation of raccoon introductions to the island, implicates canine distemper as the cause of the population decline.

Two reviews on feral cat eradications on islands

Nogales M., Martin A., Tershy B.R., Donlan C.J., Witch D., Puerta N., Wood B. & Alonso J. (2004) A review of feral cat eradication on islands. Conservation Biology, 18, 310-319.



Feral cats are directly responsible for a large percentage of global extinctions, particularly on islands. We reviewed feral cat eradication programs with the intent of providing information for future island conservation actions. Most insular cat introductions date from the nineteentb and twentieh centuries, whereas successful eradication programs bave been carried out in the last 30 years, most in the last decade. Globally, feral cats bave been removed from at least 48 islands: 16 in Baja California (Mexico), 10 in New Zealand, 5 in Australia, 4 in the Pacific Ocean, 4 in Seychelles, 3 in the sub-Antarctic, 3 in Macaronesia (Atlantic Ocean), 2 in Mauritius, and 1 in the Caribbean. The majority of these islands (75%; n = 36) are small (<5 km²).
The largest successful eradication campaign took place on Marion Island (290 km²) cat density been successfully removed from only 10 islands (21%) of >10 km²  On Cousine Island (Seychelles) cat density reached 243 cats/km², but on most islands densities did not exceed 79.2 cats/km²(n = 22; 81%). The most common methods in successful eradication programs were trapping and bunting (often with dogs; 91% from a total of 43 islands). Frequently, these methods were used togetber. Other methods included poisoning (1080; monofluoracetate in fish baits; n = 13; 31%), secondary poisoning from poisoned rats (n = 4; 10%), and introduction of viral disease (feline panleucopaenia; n = 2; 5%). Impacts from cat predastion and, more recently, the benefits of cat eradications bave been increasingly documented. These impacts and benefits, combined with the continued success of eradication campigns on larger islands, show the value and role of feral cat eradications in biodiversity conservation. However, new and more efficient techniques used in combination with current techniques will likely be needed for success on larger islands.


K. J. Campbell, G. Harper, D. Algar, C. C. Hanson, B. S. Keitt & S. Robinson. 2011. Review of feral cat eradications on islands. Pages 37-46 In: Veitch, C. R.; Clout, M. N. and Towns, D. R. (eds.).  Island invasives: eradication and management. IUCN, Gland, Switzerland

Feral cats are a substantial threat to native and endemic fauna on islands and are being eradicated with increasing frequency.  Worldwide, 87 campaigns have been completed on 83 islands, for a total area of 114,173 ha. Nineteen unsuccessful eradication attempts are known on 15 islands and lessons learnt from those failures are provided. At least five campaigns are currently underway. We review past cat eradication campaigns, and the methods used to eradicate and detect cats in those campaigns.  We also review recent advances in eradication and detection methods.  We outline proposed eradications and document a trend for increasingly larger islands being considered, but note that although post-eradication conservation impacts are generally positive, there have been some negative ecosystem impacts.

Cat eradication on Marion island

Bester, M.N., Bloomer, J.P., van Aarde, R.J., Erasmus B.H., van Rensberg P.J.J., Skinner J.D., Howell P.G. & Naude T.W. 2002. A review of the successful eradication of feral cats from sub-Antarctic Marion Island, Southern Indian Ocean. South African Journal of Wildlife Research, 32, 65-73.

This paper reviews the history of the feral cat eradication programme on sub-Antarctic Marion Island based on unpublished minutes of meetings, reports, letters, theses and published scientific papers; and reflects on the outcome of the eradication campaign. The 19-year programme comprised seven phases, commencing with a description of the effect of the cats on the Marion Island ecosystem, the characteristics of the cat population and the formulation of a management policy (phase 1: 1974–1976). Methods for control were selected and preparations were made for the implementation of the primary control measure, biological control with the feline panleucopaenia virus (phase 2: 1976/77). The virus was released in 1977 (phase 3: 1977), followed by the determination of its effects (phase 4: 1977–1980). Monitoring of the effects of the virus continued, and the secondary control measure of hunting at night was tested (phase 5: 1981–1983). Full-scale implementation of hunting and continued monitoring of the effects of both the disease and hunting followed (phase 6: 1986–1989). The inclusion of intensive trapping and poisoning as tertiary control measures culminated in the final eradication of cats from Marion Island in 1991 (phase 7: 1989–1993).

Control with padded leg-hold traps

Jolley W.J., K. J. Campbell, N.D. Holmes, D.K. Garcelon, C.C. Hanson, D. Will, B.S. Keitt1, G. Smith, A.E. Little. 2012. Reducing the impacts of leg hold trapping on critically endangered foxes by modified traps and conditioned trap aversion on San Nicolas Island, California, USA. Conservation Evidence, 9, 43-49.

Padded leg-hold live traps were used as the primary removal technique in the successful eradication of feral cats Felis silvestris catus from San Nicolas Island, California, USA. Risk of injury to endemic San Nicolas Island foxes Urocyon littoralis dickeyi, a similarly sized and more abundant non-target species, was mitigated by using a smaller trap size, modifying the trap and trap set to reduce injuries, and utilising a trap monitoring system to reduce time animals spent in traps. Impacts to foxes during the eradication campaign were further reduced by having a mobile veterinary hospital on island to treat injured foxes. Compared to other reported fox trapping efforts, serious injuries were reduced 2-7 times. Trapping efforts exceeded animal welfare standards, with 95% of fox captures resulting in minor or no injuries. Older foxes were more likely to receive serious injury. Fox captures were also reduced through aversive conditioning, with initial capture events providing a negative stimulus to prevent recaptures. Fox capture rates decreased up to six times during seven months of trapping, increasing trap availability for cats, and improving the efficacy of the cat eradication program. No aspect of the first capture event was significantly linked to the chance of recapture.

Predator preferences impact on native prey

Gaucel, S. & D. Pontier . 2005. How predator food preference can change the destiny of native prey in predator–prey systems. Biological Invasions, 7: 795–806.

The aim of this work is to develop and analyse a mathematical model for a predator-2 preys system arising in insular environments. We are interested in the evolution of a native prey population without behavioural traits to cope with predation or competition, after the introduction of alien species. Here, we consider a long living bird population with low fertility rate. We point out the effects of the preference of the predator for either juvenile or adult stages. In addition, we study the impact of alien prey introduction in such a model. We use a reaction-diffusion system with a singular logistic right hand side. The aim of this work is to bring interesting dynamics to the fore. As a first example, oscillatory behaviour takes place in the model without alien preys and when predators have an average preference coefficient. Introduction of alien preys can lead to species extinction.

Feral cat control benefits seabirds

Bonnaud, E., K. Bourgeois, D. Zarzoso-Lacoste & E. VidalCat impact and management on two Mediterranean sister islands: “The French conservation touch”.Pages 395-401 In: Veitch, C. R.; Clout, M. N. and Towns, D. R. (eds.). 2011.  Island invasives: eradication and management. IUCN, Gland, Switzerland.


Feral cats (Felis catus) are one of the most damaging introduced species for island species worldwide. While cat control or eradication is handled with increasing efficiency on uninhabited islands, the strong bond with humans, regardless of ownership, makes cat management difficult on inhabited islands. We conducted a cat-removal programme on Port-Cros Island where both the presence of humans and their cats threaten   Puffinus yelkouan, an endangered Mediterranean endemic species of burrowing petrel. The two largest French-breeding colonies of this procellariid are on the two studied islands: Port-Cros and Le Levant. The cat-removal programme was implemented on Port-Cros, with Le Levant used for comparison. Cat diet studied through scat analysis showed cats to be responsible for killing 162 ± 46 and 21 ± 4 shearwaters per cat and per year on Le Levant and Port-Cros respectively. Bird breeding parameters were monitored during seven years on Port-Cros (before and after cat removal) and three years on Le Levant. By constructing a shearwater population viability model, we calculated that the cat impact on the yelkouan shearwaters threatens the entire population in the long term and justified cat removal. We designed a conservation management plan for Port-Cros where, taking into account human presence, feral cats were live-trapped and domestic cats were sterilised. Following this two year campaign, cat predation of shearwaters ceased, followed by an increase in the shearwater breeding population. Thus, protecting seabirds from cat predation is possible, even on islands where inhabitants are notoriously reticent to any sort of cat removal programme.

Predation of cats on Mediterranean shearwater

BONNAUD, E., G. BERGER, K. BOURGEOIS, J. LEGRAND & E. VIDAL. 2012. Predation by cats could lead to the extinction of the Mediterranean endemic Yelkouan Shearwater Puffinus yelkouan at a major breeding site. Ibis, 154, 566–577


Feral cats are considered to be one of the main harmful invasive species for island species. Adult shearwaters are highly vulnerable to predation by cats. The population of the Yelkouan Shearwater Puffinus yelkouan, a species endemic to the Mediterranean, is predicted to decline, leaving only a few large breeding colonies, due to the invasion of cats. The impact of cats on the Shearwater population of Le Levant Island, one of the major breeding sites for this species, was evaluated by studying cat diet over a 2-year period. The predation rate obtained was then included in a Shearwater demographic model. Cats preyed upon rabbits, rats and Shearwaters, with a peak of predation on Shearwaters immediately upon their arrival at the colony. Cat predation was heavy and responsible for the yearly death of about 810–3241 birds. This could lead to the extinction of the Le Levant colony within the next four decades and perhaps within just a few years. Cat predation on prospecting individuals, a parameter essential to assess the real impact of predation, may not have an immediate effect on the Shearwater breeding population but can accelerate population extinction. Cat predation must be reduced or removed to prevent the extinction of one of the most important breeding sites for this species.