Evidence for domestic dogs as a source of canine distemper virus infection for Serengeti wildlife

Cleaveland, S., Appel, M. G. J., Chalmers, W. S. K., Chillingworth, C., Kaare, M., & Dye, C. (2000). Serological and demographic evidence for domestic dogs as a source of canine distemper virus infection for Serengeti wildlife. Veterinary microbiology, 72(3), 217-227.

Following an epidemic of canine distemper virus (CDV) in Serengeti lions in 1994, the role of domestic dogs in the epidemiology of the disease was investigated by serological and demographic analyses. From 1992 to 1994, data were collected from two domestic dog populations bordering the Serengeti National Park. Several lines of evidence indicated that patterns of CDV infection differed significantly between higher-density dog populations of Serengeti District to the west of the park and lower-density populations of Ngorongoro District to the south-east: (a) CDV age-seroprevalence patterns differed significantly between years in Ngorongoro District populations but not in Serengeti District populations; (b) CDV seropositive pups (<12 months of age) were detected in Ngorongoro District only in 1994, whereas a proportion of pups in Serengeti District were seropositive in each year of the study; (c) in Ngorongoro District, the proportion of deaths attributed to disease was significantly higher in 1994 than in 1993, whereas in Serengeti District, there was no significant difference in disease-related mortality between years; (d) in Ngorongoro District, significantly more CDV seronegative dogs than seropositive dogs died in 1994, whereas there was no difference in survival of CDV seropositives and seronegatives between years in Serengeti District. We concluded that, between 1992 and 1994, CDV persisted in higher-density dog populations of Serengeti District, but occurred only sporadically in lower-density Ngorongoro District populations. Data from Ngorongoro District are consistent with exposure of dogs to CDV in 1991 and 1994, but not in 1992 and 1993. These findings suggest that higher-density domestic dog populations to the west of the Serengeti National Park were a more likely source of CDV infection for wildlife during 1994 than lower-density pastoralist dogs to the south and east of the park.

Owners attitude towards cat predation on wildlife

MacDonald, E., T. Milfont and M. Gavin, 2015.What drives cat-owner behaviour? First steps towards limiting domestic-cat impacts on native wildlife. Wildlife Research - http://dx.doi.org/10.1071/WR14164
Context: Cats can have substantial negative impacts on native wildlife. To harness the collective conservation impact of owners keeping cats inside, advocacy campaigns need to be based on empirical evidence regarding potential drivers to change cat-owner behaviour.

Aims: We assessed the degree to which different socio-psychological factors (attitudes, subjective norms, and perceived behavioural control), past cat owner behaviour, demographics and group membership explained intentions of zoo visitors to bring cats inside.

Methods: A self-report questionnaire was distributed to zoo visitors based on the theory of planned behaviour. Visitors rated 24 belief statements and four behavioural-intention questions on a scale of one to seven. We adopted an information-theoretic approach to make inferences about the drivers of intention to bring cats inside.

Key results: Attitude and normative beliefs were strong predictors of intention. Specifically, attitudinal beliefs focussed on the benefits to the cat of being inside or the positive impact on the owner were correlated with intention. Bringing cats inside for the benefit of native species was weakly correlated with intention. We found an interaction between normative beliefs (injunctive and descriptive) and past behaviour. For respondents who were intermittently bringing their cat inside, veterinarians were a key injunctive normative influence. In contrast, respondents who kept their cat outside exclusively rated descriptive norms as influential on their own behaviour.

Conclusions: Our results indicated a way forward for future advocacy campaigns. To increase the frequency of visitors bringing cats inside, future research should look at campaigns using veterinarians to advocate messages that emphasise the benefits to the cat of being inside or the positive impact on the owner. To target visitors who keep their cat outside exclusively, a normative campaign highlighting the actions of others bringing their cats inside at night may prove successful.

Implications: Given the impacts cats have on wildlife, conservation campaigns need to properly design communication campaigns to have the best chance at altering cat-owner behaviour. Our results can help guide this process.

Cats seem to predate on birds with lower immunocompetence

Møller, A.P. & Erritzøe, J. 2000. Predation against birds with low immunocompetence. Oecologia. 122(4): 500–504.

Differences in the phenotypic characteristics between individuals falling prey to predators and conspecifics avoiding predation will reflect the intensity of selection on prey. If prey are generally in poor condition, we predicted that they should have an inferior health status in comparison to individuals dying for other reasons. We investigated this prediction for prey and conspecifics that did not die from predation by comparing the size of the spleen, which is an important immune defence organ reflecting one component of immunocompetence, using 18 species of passerine birds and domestic cat Felis catus predators as a model system. Prey had consistently smaller spleens than non-prey, implying that they had weak immune systems. The data set did not indicate that sex or age, month of death, body mass, body condition, liver mass, wing length or tarsus length differed significantly between prey and non-prey. Thus there was little evidence of confounding factors affecting the results. These observations indirectly suggest that disease and parasitism may play an important role in predator-prey interactions.

Mean (+SE) spleen mass (g) for birds captured by cats (Prey) and other conspecifics (Others). Numbers are sample sizes

Human and dog disturbance to shorebirds

McCrary, M. D., & Pierson, M. O. (2000). Influence of human activity on shorebird beach use in Ventura County, California. In Proceedings of the fifth California Islands symposium (pp. 424-427).

We studied the potential influence of human and dog activity on shorebird abundance at 13 sandy beaches in Ventura County, California. The 13 study beaches were randomly selected, and each beach was 1 km long. From June 1994 to May 1997, we counted all shorebirds, humans and dogs at each beach once per month for a total of 36 counts. We found no significant relationship between instantaneous counts of either shorebirds and human or dogs. However, there was a significant relationship among the 13 beaches between total shorebird and human use. The beaches with the greatest number of shorebirds (Ormond Beaches 1 through 3) were among those with the lowest number of humans. The results suggest that inaccessibility to humans may be an important aspect of shorebird habitat quality. Relatively undisturbed sandy beaches are quite rare in southern California, and the inaccessibility of the few remaining undisturbed beaches should be maintained. 

Dogs among the main causes of death of blue penguins

Hocken, A.G. (2000) Cause of death in blue penguins (Eudyptula m.minor) in North Otago, New Zealand. New Zealand Journal of Zoology, 27:4, 305-309, DOI: 10.1080/03014223.2000.9518239

I necropsied 213 blue penguins (Eudyptula m. minor) collected during 1994 to 1998, mainly from Oamaru Harbour and urban areas, the remainder from sites south to Otago Peninsula. The dominant categories were malnutrition (16%), and cause of death (15%). Where malnutrition was involved, it was usually unclear whether it was the direct cause of death or the consequence of undiagnosed natural disease or infestation. Twenty five per cent of birds died from animal attacks. Aspergillosis was the commonest natural disease (3.3%). Endoparasitism was uncommon (1.3%). This study provides significant evidence of geographic variation in infestation of blue penguins.

Virus-vectored immunocontraception to control feral cats

Courchamp, F. & S.J. Cornell. 2000. Virus-vectored immunocontraception to control feral
cats on islands: a mathematical model. Journal of Applied Ecology, 37: 903-913.

1.  Feral cats Felis catus introduced onto oceanic islands pose a major ecological threat to endemic vertebrates, but their control is difficult. Immunocontraception has not been considered previously as a method for their control or eradication, and therefore we used a modelling approach to assess whether virus-vectored immunocontraception (VVIC) might be effective.

2.  We compared the relative efficiency of cat control/eradication using immunocontraception and three different disseminating techniques, i.e. baits, genetically modified viral vectors, or both. We accounted for several forms of dynamic compensation likely to arise in a population with artificially reduced fertility.

3.  We conclude that, under the assumptions of our model, immunocontraception can control or eradicate feral cats on oceanic islands. VVIC was found to be a more efficient dissemination technique than baits, but an integrated method involving viral-infected baits was the most likely to lead to eradication.

4.  We advocate field trials of this VVIC technique, when available, under island conditions where any risks to non-target fauna would be minimal.

Cats, mice and climate change impact on Marion island's birds

Huyser, O., Ryan, P. G., & Cooper, J. (2000). Changes in population size, habitat use and breeding biology of lesser sheathbills (Chionis minor) at Marion Island: impacts of cats, mice and climate change?. Biological Conservation, 92(3), 299-310.


Impacts on the native avifauna of sub-Antarctic islands by introduced vertebrates are well documented for species such as burrowing petrels (Procellariidae), but less is known about impacts on surface-nesting species. The sub-Antarctic Prince Edward Islands, comprising Marion and Prince Edward Islands, support an endemic form of lesser sheathbill (Chionis minor). Marked differences have developed over the last 20 years in winter habitat use and population trends of sheathbills between the two islands. Currently birds at Marion forage almost exclusively along the coastline and in penguin colonies during winter, but at Prince Edward they occur at higher densities and forage throughout the coastal plain. Compared to the 1970s, sheathbills at Marion are now less abundant around most of the island, forage proportionally less in the vegetation of the coastal plain, commence breeding with a lower body mass and lay smaller clutches. These changes are likely a result of a decrease in terrestrial macro-invertebrate prey, formerly an important winter food resource for sheathbills at Marion Island. The main biological difference between the two islands is the presence of many more introduced species at Marion, including house mice (Mus musculus) and feral cats (Felis catus) (now eradicated). We suggest that house mice are impacting the sheathbill population by consuming terrestrial macro-invertebrates, and that this impact has been exacerbated by the removal of feral cats, by the massive reduction in burrowing petrels (which promote invertebrate populations through manuring), and by climatic warming (which may be promoting higher densities of mice). This proposed web of interactions between sheathbills, introduced species, invertebrates and burrowing petrels needs to be further investigated, given the likelihood of further climatic change.

Spatial organization and habitat use of feral cats in California

Hall, L. S., Kasparian, M. A., Van Vuren, D., & Kelt, D. A. (2000). Spatial organization and habitat use of feral cats (Felis catus L.) in Mediterranean California. Mammalia, 64(1), 19-28.

We report on a preliminary study of the spatial organization, habitat use, and diet of feral cants (Felis catus) in a riparian reserve in Central California, to assess potential impacts of this exotic predator on native species. Home ranges of adult cats averaged 31,7 ha and did not differ significantly by sex and season. Home ranges also showed little overlap, suggesting a territorial social system. Cats strongly preferred riparian habitats and foraged primarily on native species of small mammals, especially California voles (Microtus californicus) and Botta's pocket gophers (Thomomys bottae), although birds, insects, and exotic rodents were also eaten. The preference for riparian habitats and native preys suggests that impacts on biodiversity by feral cats may be great, especially in Mediterranean climates where riparian communities already are heavily impacted by urbanisation and agriculture.

Evaluating two census methods

Edwards, G. P., De Preu, N. D., & Crealy, B. S. I. (2000). An evaluation of two methods of assessing feral cat and dingo abundance in central Australia.Wildlife Research, 27(2), 143-149.

We evaluated the efficacy of spotlight surveys and passive track surveys conducted along roads for assessing the relative abundance of feral cats and dingoes in a semi-arid rangeland environment in central Australia. Track surveys were more time-efficient than spotlight surveys and offered higher precision. We cover a range of issues that need to be considered when using track-based surveys to assess population change. We also discuss the merits of other techniques used to monitor the abundance of mammalian carnivores.

Eradication of feral cats from Gabo island, Victoria

Twyford, B. K. L., Humphrey, P. G., Nunn, R. P., & Willoughby, L. (2000). Eradication of Feral Cats (Felis catus) from Gabo Island, south‐east Victoria.Ecological Management & Restoration, 1(1), 42-49.

Concerns about the effects of predation by Feral Cats (Felis catus) on native fauna, particularly breeding seabirds, precipitated a decision in 1987 to control and eventually eradicate cats from Gabo Island. The size of the population prior to control was at least 30 animals. A control programme, undertaken between 1987 and 1991, centred on shooting, trapping and an extensive 1080 poison-baiting programme. Trapping and shooting were ineffectual. Poisoning was the most successful and effective technique for the rapid and widespread reduction in the Feral Cat population on Gabo Island. The effectiveness of dead 1-day-old chickens as a poison carrier was demonstrated. Effective poison baiting was attributed to bait selection and strategic timing of baiting to periods when prey was at low levels. Outcomes from the trapping programme and post-control monitoring strongly suggested that the cat population had been reduced to only two or three animals, possibly of the same sex. Monitoring between 1992 and 1998 failed to record any evidence of cats, indicating that the cats remaining after poison baiting had been unable to sustain a viable population. On the basis of the available evidence, Feral Cats appear to have been successfully eradicated from Gabo Island.

Impact of cats and foxes on the small vertebrate fauna in Western Australia

Short, J., Calver, M. C., & Risbey, D. A. (1999). The impact of cats and foxes on the small vertebrate fauna of Heirisson Prong, Western Australia. I. Exploring potential impact using diet analysis. Wildlife Research, 26(5), 621-630.

The diets of cats (Felis catus) and foxes (Vulpes vulpes) killed during predator control at a semi-arid site in Western Australia were studied to see which prey species may be affected by predation from these introduced predators. The number of items, biomass and frequency of occurrence of each food type in the gut contents from 109 fetal cats, 62 semi-feral cats and 47 foxes were used to calculate an Index of Relative Importance for each food category for each predator. Mammals were the most important prey group for all three predators, with rabbit being the most highly ranked prey species. The diets of feral and semi-feral cats were similar in dietary diversity but differed in the frequency of occurrence of some food categories. Native rodents, birds and reptiles occurred more frequently and were ranked higher in the diet of feral cats, and food scraps occurred more frequently in the diet of semi-feral cats. The diet of foxes was less diverse than that of either group of cats. Invertebrates and sheep carrion were more important prey categories for foxes than for cats. In the summer-autumn period, foxes ate more sheep carrion and invertebrates than they did in winter-spring. The diet of feral cats was more diverse in summer-autumn, including a greater range of invertebrates and more rodents, birds and reptiles than in the winter-spring period. We predict that cats are more likely to have an impact on small vertebrates at this site and that the control of cats could lead to recoveries in the populations of native rodents, birds and reptiles. By contrast, the control of foxes alone may lead to a rise in cat numbers and a consequent detrimental impact on small vertebrate populations.


Risbey, D. A., Calver, M. C., Short, J., Bradley, J. S., & Wright, I. W. (2000). The impact of cats and foxes on the small vertebrate fauna of Heirisson Prong, Western Australia. II. A field experiment. Wildlife Research, 27(3), 223-235.

The hypothesis that predation by feral cats and introduced foxes reduces population sizes of small, native vertebrates was supported by results of a predator-removal experiment at Heirisson Prong, a semi-arid site in Western Australia. The methods of control used against cats and foxes to protect native mammals reintroduced to Heirisson Prong produced three broad ‘predator zones’: a low-cat and low-fox zone, where foxes were eradicated and spotlight counts of cats declined after intensive cat control; a high-cat and low-fox zone where spotlight counts of cats increased three-fold after foxes were controlled; and a zone where numbers of cats and foxes were not manipulated. Small mammals and reptiles were monitored for one year before and three years after predator control began. Captures of small mammals increased in the low-cat and low-fox zone, but where only foxes were controlled captures of small mammals declined by 80%. In the absence of cat and fox control, captures of small mammals were variable over the sampling period, lower than where both cats and foxes were controlled, yet higher than where only foxes were controlled. The capture success of reptiles did not appear to be related to changes in predator counts. This study presents the first experimental evidence from mainland Australia that feral cats can have a negative impact on populations of small mammals.

People and dogs in rural Zimbabwe

Butler, J.R. & Bingham, J. 2000. Demography and dog-human relationships of the dog population in Zimbabwean communal lands. Veterinary Record, 147: 442-446.

Dogs are Zimbabwe's primary vector for rabies, and the majority live in communal lands (traditional agropastoralist rural areas). In 1994, a household questionnaire survey was conducted to provide baseline data on the demography and dog-human relationships of the dogs in the communal lands. The survey showed that all the dogs were owned, and there was no evidence of a feral population. They were unrestricted and semi-dependent on people. The numbers of dogs per capita varied little in each communal land, resulting in higher dog densities in communal lands with higher human densities, and indicating that people were not intolerant of dogs at higher densities. The population turnover was rapid: the life expectancy of the dogs was 1.1 years, the mean age 2.0 years, and 71.8 per cent died in their first year. The population was heavily skewed towards juveniles, with 40.8 per cent aged less than 12 months. Despite the high juvenile mortality, the population was growing by 6.52 per cent per annum. It was estimated that in 1994 there were 1.36 million dogs in communal lands.

Cats' diet on some Pacific islands

Jarvis and Howlnad

R.D. Kirkpatrick and Mark J. Rauzon. 1986. Foods of Feral Cats Felis catus on Jarvis and Howland Islands, Central Pacific Ocean. Biotropica, 18 (1): 72-75

Food habits of feral cats (Felis catus) were studied on two small uninhabited islands in the central Pacific Ocean. Cat stomach contents, collected on Howland Island in May 1979 and on Jarvis Island during May 1979 and June-July 1982, revealed that sooty terns (Sterna fuscata) were the primary prey species. Other seabirds, lizards, insects and, on Jarvis Island, house mice were also eaten. Fetal cats may have virtually exterminated the wedge-tailed shearwater colony on Jarvis Island.

Kermadec
Fitzgerald, B.M.; Kark, B.J. & Veitch, C.R. 1991. The diet of feral cats (Felis catus) on Raoul Island, Kermadec Group. New Zealand Journal of Ecology 15(2): 123-129.

Feral cats became established on Raoul Island some time between 1836 and 1872; the prey available to them included a great variety of nesting seabirds, few of which are present now, landbirds and kiore (Rattus

exulans). Norway rats reached the island in 1921, providing additional prey for cats, but also another potential predator of seabirds. The diet of cats is described from guts and scats collected between 1972 and 1980. Rats are the main food, with land birds second in importance, and seabirds are now a minor item. More than 90% of the rats eaten by cats are kiore although more Norway rats than kiore are trapped. Eradicating cats from Raoul Island is feasible but because Norway rats too are important predators of birds on islands, it is likely that eradicating cats without also eradicating Norway rats will do little to restore the diversity of bird species on Raoul Island, although the densities of a few species now present might be increased.

Hawai'i
Hess, S. C.; Hansen, H.; Nelson, D.; Swift, R. & Banko, P. C. 2007. Diet of feral cats in Hawai'i Volcanoes National Park. Pacific Conservation Biology, 13: 244–249.

We documented the diet of feral cats by analysing the contents of 42 digestive tracts from Kilauea and Mauna Loa in Hawai'i Volcanoes National Park. Small mammals, invertebrates, and birds were the most common prey types consumed by feral cats. Birds occurred in 27.8-29.2% of digestive tracts. The total number of bird, small mammal, and invertebrate prey differed between Kilauea and Mauna Loa. On Mauna Loa, significantly more (89%) feral cats consumed small mammals, primarily rodents, than on Kilauea Volcano (50%). Mice (Mus musculus) were the major component of the feral cat diet on Mauna Loa, whereas Orthoptera were the major component of the diet on Kilauea. We recovered a mandible set, feathers, and bones of an endangered Hawaiian Petrel (Pterodroma sandwichensis) from a digestive tract from Mauna Loa. This specimen represents the first well-documented endangered seabird to be recovered from the digestive tract of a feral cat in Hawai'i and suggests that feral cats prey on this species.

Smucker, T. D., G. D. Lindsey, & S. M. Mosher. 2000. Home range and diet of feral cats in Hawaii forests. Pacific Conservation Biology 6: 229–237.

Feral cat Felis catus home range in a Hawaiian montane wet forest and their diet in three habitats - montane wet forest, subalpine dry forest, and lowland dry forest - were determined to provide baseline ecological data and to assess potential impacts to native terrestrial fauna. Seven cats (three males and four females) were captured in 624 trap nights. Mean weight of adult cats was 2.85 0.27 (SE) kg for males and 1.87 0.03 kg for females. Mean diurnal home range using the adaptive kernel method was 5.74 2.73 km² for three males and 2.23 0.44 km²  for two females. Daytime locations were always within the montane wet forest with the borders on one or more sides of the home ranges of all cats defined by open grassland pastures. Rodents comprised the majority of the cat diets in all three habitats, with the frequencies of occurrence between 0.88 and 0.91. Bird remains were a regular component of the diet of cats, with montane wet forest having the highest frequency of occurrence (0.68), followed by subalpine dry forest (0.53). and lowland dry forest (0.21).

Toxoplasmosis affecting endangered native Hawaiian bird

Work,T.M.,  J. G. Massey, B.A. Rideout, C.H. Gardiner, D. B. Ledig, O. C. H. Kwok & J. P. Dubey. 2000. Fatal toxoplasmosis in free-ranging endangered 'Alala from Hawaii. Journal of Wildlife Diseases, 36(2): 205–212

The ‘Alala (Corvus hawaiiensis) is the most endangered corvid in the world, and intensive efforts are being made to reintroduce it to its former native range in Hawaii. We diagnosed Toxoplasma gondii infection in five free-ranging ‘Alala. One ‘Alala, recaptured from the wild because it was underweight and depressed, was treated with diclazuril (10 mg/kg) orally for 10 days. Antibodies were measured before and after treatment by the modified agglutination test (MAT) using whole T. gondii tachyzoites fixed in formalin and mercaptoethanol. The MAT titer decreased four-fold from an initial titer of 1:1,600 with remarkable improvement in physical condition. Lesions of toxoplasmosis also were seen in two partially scavenged carcasses and in a third fresh intact carcass. Toxoplasma gondii was confirmed immunohistochemically by using anti-T. gondii specific serum. The organism was also cultured by bioassay in mice from tissues of one of these birds and the brain of a fifth ‘Alala that did not exhibit lesions. The life cycle of the parasite was experimentally completed in cats. This is the first record of toxoplasmosis in ‘Alala, and the parasite appears to pose a significant threat and management challenge to reintroduction programs for ‘Alala in Hawaii.

Transmision modes for FPLV

Berthier, K., M. Langlais, P. Auger, & D. Pontier. 2000. Dynamics of a feline virus with two transmission modes within exponentially growing host populations. Proceedings of the Royal Society, Biological Sciences, 267(1457): 2049–2056.

Feline panleucopenia virus (FPLV) was introduced in 1977 on Marion Island (in the southern Indian Ocean) with the aim of eradicating the cat population and provoked a huge decrease in the host population within six years. The virus can be transmitted either directly through contacts between infected and healthy cats or indirectly between a healthy cat and the contaminated environment: a specific feature of the virus is its high rate of survival outside the host. In this paper, a model was designed in order to take these two modes of transmission into account. The results showed that a mass-action incidence assumption was more appropriate than a proportionate mixing one in describing the dynamics of direct transmission. Under certain conditions the virus was able to control the host population at a low density. The indirect transmission acted as a reservoir supplying the host population with a low but sufficient density of infected individuals which allowed the virus to persist. The dynamics of the infection were more affected by the demographic parameters of the healthy hosts than by the epidemiological ones. Thus, demographic parameters should be precisely measured in field studies in order to obtain accurate predictions. The predicted results of our model were in good agreement with observations.

Hybridisation dog/wolf

Randi, E., V. Lucchini, M.F. Christensen, N. Mucci, S.M. Funk, G. Dolf & V. Loeschcke. 2000. Mitochondrial DNA Variability in Italian and East European Wolves: Detecting the consequences of Small Population Size and Hybridization. Conservation Biology, 14 (2): 464-473

The Italian wolf (Canis lupus) population has declined continuously over the last few centuries and become isolated as a result of the extermination of other populations in central Europe and the Alps during the nineteenth century. In the 1970s, approximately 100 wolves survived in 10 isolated areas in the central and southern Italian Apennines. Loss of genetic variability, as suggested by preliminary studies of mitochondrial DNA (mtDNA) sequences, hybridization with feral dogs, and the illegal release of captive, non-native wolves are considered potential threats to the viability of the Italian wolf population. We sequenced 546 base pairs of the mtDNA control region in a comprehensive set of Italian wolves and compared them to those of dogs and other wolf populations from Europe and the Near East. Our data confirm the absence of mtDNA variability in Italian wolves: all 101 individuals sampled across their distribution in Italy had the same, unique haplotype, whereas seven haplotypes were found in only 26 wolves from an outbred population in Bulgaria. Most haplotypes were specific either to wolves or dogs, but some east European wolves shared haplotypes with dogs, indicative of hybridization. In contrast, neither hybridization with dogs nor introgression of non-native wolves was detected in the Italian population. These findings exclude the introgression of dog genes via matings between male wolves and female dogs, the most likely direction of hybridization. The observed mtDNA monomorphism is the possible outcome of random drift in the declining and isolated Italian wolf population, which probably existed at low effective population size during the last 100–150 years. Low effective population size and the continued loss of genetic variability might be a major threat to the long-term viability of Italian wolves. A controlled demographic increase, leading to recolonization of the historical wolf range in Italy, should be enforced.


La población del lobo Italiano (Canis lupus) ha disminuido continuamente a lo largo de los últimos siglos y se ha aislado como resultado de la exterminación de otras poblaciones en Europa central y los Alpes durante el siglo diecinueve. En los años 70, aproximadamente 100 lobos sobrevivieron en 10 áreas aisladas de los Apeninos centrales y del sur. La pérdida de variabilidad genética, como lo han sugerido estudios preliminares de secuencias de ADN mitocondrial (ADNmt), la hibridización con perros silvestres, y la liberación ilegal de lobos cautivos no nativos son consideradas amenazas potenciales para la viabilidad de las poblaciones italianas de lobos. Secuenciamos 546 pares de bases de la región control del ADNmt en un grupo amplio de lobos italianos y los comparamos con perros y otras poblaciones de lobos de Europa y del Cercano Oriente. Nuestros datos confirman la ausencia de variabilidad en el ADNmt en los lobos italianos: Los 101 individuos muestreados a lo largo de su distribución en Italia tuvieron el mismo haplotipo único, mientras que se encontraron siete haplotipos en tan solo 26 lobos de la población de Bulgaria. La mayoría de los haplotipos fueron específicos a los lobos o a los perros, pero algunos lobos del este de Europa compartieron haplotipos con los perros, indicando hibridización. En contraste, ni la hibridización con perros, ni la introgresión de lobos no nativos fue detectada en la población italiana. Estos resultados excluyen la introgresión de genes de perros mediante cruzas entre lobos machos y hembras de perros, la dirección más probable de hibridización. El monomorfismo de ADNmt observado es el posible resultado de la deriva génica en el declive de la población aislada del lobo italiano, la cual probablemente ha existido en un tamaño poblacional efectivo bajo durante por lo menos los últimos 100–150 años. El bajo tamaño poblacional efectivo y la continua pérdida de variabilidad genética podría ser una mayor amenaza para la viabilidad a largo plazo del lobo italiano. Un incremento demográfico controlado, que conduzca hacia la recolonización del rango histórico del lobo en Italia, debería ser puesto en ejecución.


See more about wild canid hybridisation with dogs

Rabbits killing birds

Courchamp, F., M. Langlais & G. Sugihara. 2000. Rabbits killing birds: modelling the hyperpredation process. Journal of Animal Ecology, 69 (1): 154-164

1. Introduced rabbits are known to have catastrophic effects on oceanic islands, either by direct destruction of the vegetative cover, or by the resulting disturbance of indigenous vertebrates.

2. Another dramatic effect, less well known, but potentially of major importance, is the hyperpredation process. This process, related to apparent competition, predicts that an introduced prey species, well adapted to high predation pressure, could induce the extinction of an indigenous prey, through the sudden increased population size of an introduced predator. In many island ecosystems, the simultaneous presence of introduced feral cats and rabbits is thus potentially a further threat for small vertebrates endemic of these islands.

3. Through a mathematical model, we tested this hypothesis, using a tri-trophic system comprising an indigenous prey (birds), an introduced prey (rabbits) and an introduced predator (cats), and we demonstrated the theoretical existence of the hyperpredation process.

4. In addition, the numerical analysis of the model allowed a quantification of this process. It shows that the conditions required for an indigenous species to cope with the hyperpredation process imply very high intrinsic growth rates and/or carrying capacity, as well as behavioural anti-predator response to the introduced predator. Since these conditions are unlikely to be met, this process is a further potential threat to most indigenous vertebrate prey.

5. Finally, our model shows that, although it can be induced by both types of adaptation together or alone, behavioural adaptations alone are more powerful in generating the hyperpredation process, than are life history traits adaptations.