Cats "protecting" birds

Courchamp F, Langlais M, Sugihara G. 1999. Cats protecting birds: Modelling the mesopredator release effect. Journal of Animal Ecology, 68: 282–292

1- Introduced predators account for a large part of the extinction of endemic insular species, which constitutes a major component of the loss of biodiversity among vertebrates. Eradication of alien predators from these ecosystems is often considered the best solution.
2- In some ecosystems, however, it can generate a greater threat for endemic prey, through what is called the "mesopredator release". This process predicts that, once superpredators are suppressed, a burst of mesopredators may follow that leads their shared prey to extinction.
3- This process is studied through a mathematical model describing a three species system (prey-mesopredator-superpredator). Analysis of the model, with and without control of meso- and superpredators, shows that this process does indeed exist and can drive shared prey to rapid extinction.
4- This work emphasises that, although counter-intuitive, eradication of introduced superpredators, such as feral domestic cats, is not always the best solution to protect endemic prey when introduced mesopredators, such as rats, are also present.

Cats, toxoplasmosis and human culture

Lafferty, K.D.2006. Can the common brain parasite,Toxoplasma gondii, influence human culture? Proceedings of the Royal Society B: Biological Sciences 273: 2749-2755

The latent prevalence of a long-lived and common brain parasite,Toxoplasma gondii, explains a statistically significant portion of the variance in aggregate neuroticism among populations, as well as in the ‘neurotic’ cultural dimensions of sex roles and uncertainty avoidance. Spurious or non-causal correlations between aggregate personality and aspects of climate and culture that influence T. gondii transmission could also drive these patterns. A link between culture and T. gondii hypothetically results from a behavioural manipulation that the parasite uses to increase its transmission to the next host in the life cycle: a cat. While latent toxoplasmosis is usually benign, the parasite's subtle effect on individual personality appears to alter the aggregate personality at the population level. Drivers of the geographical variation in the prevalence of this parasite include the effects of climate on the persistence of infectious stages in soil, the cultural practices of food preparation and cats as pets. Some variation in culture, therefore, may ultimately be related to how climate affects the distribution of T. gondii, though the results only explain a fraction of the variation in two of the four cultural dimensions, suggesting that if T. gondii does influence human culture, it is only one among many factors.

Cats, rats and seabirds

Le Corre, M. 2008. Cats, rats and seabirds. Nature, 451: 134-135.
Cats kill birds, and therefore eradicating cats from an island would seem to be a good strategy for protecting the native population of seabirds. But that thinking does not take account of ecological complications.

Cats' diet in rural Poland

Krauze-Gryz, D., J. Gryz, J. Goszczyński. 2012. Predation by domestic cats in rural areas of central Poland: an assessment based on two methods, Journal of Zoology, 288 (4): 260-266

Studies of cat trophic behaviour can be based on collections of the prey brought home or the prey eaten by cats (i.e. analyses of scat/gut contents). Both methods involve biases with respect to palatability, prey size and assessment of hunting rates. Furthermore, these methods are often used on different groups of cats (i.e. house-based vs. feral), thus results are difficult to compare. In the present study, cats from the same area (rural areas in central Poland) were studied by both methods: prey brought home and prey eaten (scat and gut analyses). Both methods identified mammals as the most frequent prey (followed by birds). However, differences occurred in the percentages of the four main vertebrate groups brought home versus eaten by cats: reptiles tended to be brought home, whereas amphibians tended to be eaten. No such difference was found for birds and mammals. Second, the relative proportions of presumably more palatable and presumably less palatable prey differed. The relative proportions of mice and voles (the latter eaten more frequently) and the relative proportions of soricomorphs and rodents (the latter eaten more frequently) were different. Finally, small prey items (i.e. invertebrates) were recorded incompletely for the brought-home method. Overall, the prey-brought-home method underrepresented small prey and underestimated the predation rate for cats, whereas the prey-eaten method was less likely to record unpalatable prey. We thus recommend to combine these two methods to obtain fuller and truer assessment of cat predation.

Cats reduce effective protected area

Wierzbowska, I.A, J.Olko, M.Hędrzak, K.R. Crooks. 2012. Free-ranging domestic cats reduce the effective protected area of a Polish national park, Mammalian Biology - Zeitschrift für Säugetierkunde, 77 (3) 204

Poland's Animal Protection Act, as of 2002, made it legal to shoot free-ranging cats and dogs. The act triggered substantial social debate with opponents arguing that this legislation was weakly supported by scientific evidence of the ecological impacts of free-ranging pets. Our main research goal was to examine the activity of free-ranging domestic cats within a Polish protected area by applying radio-telemetry methods to determine space use and degree of encroachment into the national park. We trapped and radio-tracked 19 animals from three sites (focal households) located in Ojcow National Park (ONP) in southern Poland from June 2003 to March 2006. Annual 100% MCP home range size varied from 0.02 km² to 1.46 km², and was significantly larger for males (mean ± SE = 0.79 ± 0.34 km²; median = 0.53 km²) than for females (mean ± SE = 0.13 ± 0.05 km²; median = 0.13 km²). The distance travelled by individual cats from focal sites did not significantly differ between males (mean ± SE = 232.00 ± 21.05 m; median = 191 m) and females (mean ± SE = 232.50 ± 12.47 m; median = 228 m), with maximum distances of 1.5 km for males and 1.1 km for females. All monitored cats were in close proximity to nature reserves and ranged into protected areas without any human control. Cats living in the households in the park and its surrounding buffer zone, roaming at 200 m and 1000 m radius distances from their households, occupied from 6% to 100% of the park area, respectively. Our results reveal that free-ranging domestic cats roam through and potentially impact the entire national park, thus reducing its effective protected area.

Canine exiles from Constantinople

THE ADVERTISER, ADELAIDA, MONDAY, OCTOBER 3, 1910

SUFFERING DOGS 

THE CANINE EXILES FROM CONSTANTINOPLE

Further particulars have been received regarding the condition of the «crowds of dogs» collected from the streets of Constantinople and placed on a neighboring island. In response to protests, it was stated that the dogs were to be killed, but nothing has been done.An account of their terrible ' plight is given in a message from Reuter’s Constantinople representative, -who states:-"In company with a party of English and American friends, I visited the Island of Oxia, in the Sea of Marmora, the place of exile of the dogs. A picture of misery and desolation met our eyes. Dead and dying animals were to be seen everywhere. I saw dogs eating their dead companions. We were soon covered with flies, and were only able to shake them off when we got out to sea again. There were many dogs which still preserved their robust and fit appearance, but the lack of fresh water will doubtless bring those to the same stage as the others. In two respects I noticed an improvement There were some half-dozen men on the island who fed the dogs twice a day, for which purpose bread is imported weekly. The dogs greeted us on landing by wagging their tails and brushing up against us, so if to say, "Take us away from this inhospitable place." Several actually tried to swim behind the dinghy when leaving the island, but soon had to abandon the attempt owing to their weak condition. The men lived in a wooden hut on the elevated part of the island. I was informed by them that there were some 40.000 dogs in the place, though this is evidently an exaggeration. Probably half that number would be nearer the mark and include the total deportation thus far. The death-rate was about 200 a day. An industry has been started on the island by a Frenchman, who skins the dead carcases and boils them for the purpose of extracting the bones, both, skin and bones being exported to Europe. Fresh arrivals at the island now take place once a week only, as the supply is fast diminishing, which is not surprising, seeing that the city has been practically cleared of dogs."

See also Barking island

The dogs of Istambul

Pinguet, C. 2008. Les chiens d'Istanbul, Saint-Pourçainsur-Sioule: Bleu Autour

Catherine Pinguet’s Les chiens d’Istanbul (The Dogs of Istanbul) explores the history of stray dogs in Istanbul. The book sheds light on a neglected facet of the past – the perception of dogs by different cultures and religions. Pinguet tellgs the readers about the massacre of Istanbul's stray dogs in 1910 by offering accounts from travelogues and from residents of the city, along with visual materials such as photographs and cartoons. She also covers contemporary issues such as animal shelters, animal rights and societies for animal protection. Les chiens d’Istanbul reflects on a silent aspect of history and interjects itself well into the history of animal welfare as a whole. Pinguet’s humanitarian tone and comparative analysis powerfully relate the story to readers ...

See also Barking island

Overview of the impacts of feral cats on Australian native fauna

Chris R.Dickman. 1996. Overview of the Impacts of Feral Cats on Australian Native Fauna. Institute of Wildlife Research and School of Biological Sciences. University of Sydney. Australian Nature Conservation Agency. Pp. 97.

This report provides an overview of the impact of feral cats Felis catus on native fauna of the Pacific region, with particular reference to Australia and its island territories. In Australia, cats take a wide variety of native species of mammals, birds and reptiles, but show evident preference for young rabbits or small marsupials where these are available. Reptiles are taken primarily in and habitats, while birds often feature predominantly in the diet of cats on islands. Despite their catholic diet, population-level impacts of feral cats on native fauna have been poorly documented. There is considerable potential for competition to occur between cats and carnivorous species such as quolls and raptors, but no critical evidence has yet been adduced. There is also potential for amerisal impacts to occur, either via transmission of the pseudophyllidean tapeworm Spirometra erinacei or of the protozoan parasite Toxoplasma gondii, but evidence for deleterious effects in freeliving animals is not compelling. Direct predatory impacts have been inferred from anecdotal and historical evidence, more strongly from failed attempts to reintroduce native species to their former ranges, and most critically from the decimation of island faunas and responses of prey species following experimental removal of cats or reduction of cat numbers. Attributes of the biology of feral cats and their prey species derived from the literature review were used to develop a rank-scoring system to assess the susceptibility of native species to cat predation. Species listed federally as endangered or vulnerable were designated as being at zero, low or high risk of impact from cats according to their attribute scores, and their distributions mapped from primary sources and actual locality data. Based on the number of threatened species they contain, localities and regions within Australia were placed in order of priority for future research to clarify the precise impacts of feral cats. Although difficult and expensive to carry out, controlled and replicated field removal experiments are recommended to elucidate cat impacts in all mainland areas. Removal of cats should take place also on offshore islands and island territories, but only if pilot studies show that this will not release populations of alternative predator species such as introduced rats. If release appears likely, cats should be removed only as a component of an integrated control program that targets all relevant predators.

Barking island

En 1910, miles de perros callejeros fueron enviados a la isla desierta de Sivriada u Oχeia ( Ὀξεία) en el mar de  Marmara, para evitar su presencia en las calles de Estambul. Un corto de 2010 nos ilustra la historia.

In 1910, thousands of dogs were sent to Sivriada ( Ὀξεία, Oχeia) Island in Marmara Sea, close to Istambul, to avoid their presence in the streets. A shortfilm tells us the story.

¿Cuánto matan los gatos?

How much do cats actually kill?

Un reciente cómic ilustra muy gráficamente los resultados de un estudio llevado a cabo por la Universidad de Georgia y National Geographic. El autor concluye que los gatos matan "por diversión" en la mayor parte de los casos.


El estudio, realizado con cámaras que portaban las mascotas muestra que sólo una pequeña proporción de las presas son detectadas por los dueños, mientras que una parte es consumida y el resto abandonada.

Además, el estudio ponía de manifiesto las situaciones arriesgadas a las que se exponían las mascotas.

Spatio-Temporal variation in predation by cats

Thomas R.L., Fellowes M.D.E., Baker P.J. (2012) Spatio-Temporal Variation in Predation by Urban Domestic Cats (Felis catus) and the Acceptability of Possible Management Actions in the UK. PLoS ONE 7(11): e49369. doi:10.1371/journal.pone.0049369

Urban domestic cat (Felis catus) populations can attain exceedingly high densities and are not limited by natural prey availability. This has generated concerns that they may negatively affect prey populations, leading to calls for management. We enlisted cat-owners to record prey returned home to estimate patterns of predation by free-roaming pets in different localities within the town of Reading, UK and questionnaire surveys were used to quantify attitudes to different possible management strategies. Prey return rates were highly variable: only 20% of cats returned ≥4 dead prey annually. Consequently, approximately 65% of owners received no prey in a given season, but this declined to 22% after eight seasons. The estimated mean predation rate was 18.3 prey/cat/year but this varied markedly both spatially and temporally: per capita predation rates declined with increasing cat density. Comparisons with estimates of the density of six common bird prey species indicated that cats killed numbers equivalent to adult density on c. 39% of occasions. Population modeling studies suggest that such predation rates could significantly reduce the size of local bird populations for common urban species. Conversely, most urban residents did not consider cat predation to be a significant problem. Collar-mounted anti-predation devices were the only management action acceptable to the majority of urban residents (65%), but were less acceptable to cat-owners because of perceived risks to their pets; only 24% of cats were fitted with such devices. Overall, cat predation did appear to be of sufficient magnitude to affect some prey populations, although further investigation of some key aspects of cat predation is warranted. Management of the predation behavior of urban cat populations in the UK is likely to be challenging and achieving this would require considerable engagement with cat owners.

Rabbits killing birds revisited

Zhang, J., M Fan & Y. Kuang. 2006. Rabbits killing birds revisited. Biosciences, 203:100-123


We formulate and study a three-species population model consisting of an endemic prey (bird), an alien prey (rabbit) and an alien predator (cat). Our model overcomes several model construction problems in existing models. Moreover, our model generates richer, more reasonable and realistic dynamics. We explore the possible control strategies to save or restore the bird by controlling or eliminating the rabbit or the cat when the bird is endangered. We confirm the existence of the hyperpredation phenomenon, which is a big potential threat to most endemic prey. Specifically, we show that, in an endemic prey–alien prey–alien predator system, eradication of introduced predators such as the cat alone is not always the best solution to protect endemic insular prey since predator control may fail to protect the indigenous prey when the control of the introduced prey is not carried out simultaneously.

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.

1.000.000.000 birds per year in USA!!

Dauphine, N. & R.J. Cooper. 2009. Impacts of free-ranging domestic cats (Felis catus) on birds in the United States: a review of recent research with conservation and management recommendations. Proceedings of the Fourth International Partners in Flight Conference: Tundra to Tropics: 205–219

Las aves americanas se enfrentan a un estimado de 117 a 157 millones de depredadores exóticos en la forma de gatos domésticos (Felis catus) en condición de libertad, los cuales probablemente matan anualmente al menos, mil millones de aves cada año en Estados Unidos. Los gatos han contribuido a la declinación y extinción de las aves a nivel mundial, y pueden ser la mayor causa de la extinción global de las aves luego de la destrucción de hábitat.  En este articulo, yo reviso la reciente investigación científica sobre el impacto que los gatos en condición de libertad causan a las poblaciones de aves en los Estados Unidos, con énfasis en su amenaza a las aves migratorias. Estudios han demostrado que los gatos constituyen una  amenaza importante para muchas poblaciones de aves, incluyendo aquellas especies cuya conservación es prioritaria, a través de la depredación de adultos, las nidadas y los juveniles, compitiendo también con depredadores nativos, tales como las aves de presa. En adicción a la mortalidad directa causada, los gatos causan reducciones en la fecundidad y supervivencia en las aves expuestas al riesgo de depredación,  las mismas que potencialmente y substancialmente dañan y reducen las poblaciones.  Acciónas efectivas para la conservación de las aves requerirá del fortalecimiento y aplicación de leyes que prohíben los gatos en condición de libertad, muchas de las cuales ya han sido promulgadas, así como también una mejora sustancial en la educación y que este esfuerzo por enfrentar los problemas que son causados por los gatos llegue al público en general, y producir métodos para controlar las poblaciones y movimientos de los gatos en condición de libertad.

Feral cat at an illegal cat colony in McAllen, TX, February 2008

 American birds face an estimated 117 to 157 million exotic predators in the form of free-ranging domestic cats (Felis catus), which are estimated to kill at least one billion birds every year in the United States. Cats have contributed to declines and extinctions of birds worldwide and are one of the most important drivers of global bird extinctions. In this paper, we review recent scientifi c research on the impacts of free-ranging cats on birds, with an emphasis on threats to migratory landbirds in the United States. Studies have shown that cats pose threats to many bird populations, including priority species for conservation, through their predation of adult, nestling, and juvenile birds. Cats also have impacts on birds through competition with native predators such as raptors, and through the harboring and transmission of zoonotic and other diseases to birds and other wildlife. In addition to direct mortality, cats may also cause stress responses in birds due to predation risk that may result in bird population declines. A substantial increase in public outreach is urgently needed to educate citizens about the conservation and welfare problems caused and faced by outdoor cats. Effective cat and wildlife management in this context will also require strengthening and enforcing policies and laws that control outdoor cats, many of which are already in place.

Cat-killed Eastern Towhee (Pipilo erythrophthalmus), a PIF-designated species of regional conservation concern, Athens, GA, January 2008

Read more national surveys results on cat predation

Cat fear

Beckerman, A.P., M. Boots & K.J. Gaston. 2007. Urban bird declines and the fear of cats. Animal Conservation, 10 (3): 320-325

The role of domestic cats Felis catus in the troubling, on-going decline of many urban bird populations in the UK is controversial. Debate, in the UK and elsewhere, has centred on the level of avian mortality directly imposed by cats, and on whether this is principally compensatory (the ‘doomed surplus’ hypothesis) or additive (the ‘hapless survivor’ hypothesis). However, it is well established that predators also have indirect, sub-lethal effects on their prey where life-history responses to predation risk affect birth and death rates. Here, using a simple model combining cat predation on birds with a sub-lethal (fear) effect of cat density on bird fecundity, we show that these sub-lethal effects may be substantial for urban songbirds. When cat densities are as high as has been recorded in the UK, and even when predation mortality is low (e.g. <1%), a small reduction in fecundity due to sub-lethal effects (e.g. <1 offspring /year/cat) can result in marked decreases in bird abundances (up to 95%). Thus, low predation rates in urban areas do not necessarily equate with a correspondingly low impact of cats on birds. Sub-lethal effects may depress bird populations to such an extent that low predation rates simply reflect low prey numbers.