Impact of feral pets on island iguanas

Iverson, J. B. (1978). The impact of feral cats and dogs on populations of the West Indian rock iguana, Cyclura carinata. Biological Conservation,14(1), 63-73.

A population of rock iguanas, Cyclura carinata, inhabiting Pine Cay in the Caicos Islands was nearly extirpated during the three years following construction of a hotel and tourist facility. The decline, from an estimated adult lizard population of nearly 5500, was due primarily to predation by domestic dogs and cats introduced to the island simultaneously with hotel construction. Population declines on other nearby islands were also attributed to predation by these feral mammals.

Fearing the predator: Sublethal effects of cats

Bonnington, C., Gaston, K. J., Evans, K. L. (2013), Fearing the feline: domestic cats reduce avian fecundity through trait-mediated indirect effects that increase nest predation by other species. Journal of Applied Ecology, 50: 15–24.

Summary

Urban areas contain high densities of non-native species, which in the UK include the domestic cat Felis catus (Linnaeus 1758) and the grey squirrel Sciurus carolinensis (Gmelin 1788). The direct predation effects of domestic cats on prey populations attract intense debate, and such influences of the nest-predatory grey squirrel are receiving increasing attention. In contrast, theory predicts that sublethal and indirect effects are more important, but empirical evidence is currently lacking.

We conducted controlled model presentation experiments at active urban blackbird Turdus merula (Linnaeus 1758) nests to provide the first empirical evidence that quantifies the potential sublethal and indirect effects of predators (domestic cat and grey squirrel) on avian reproductive success.

Domestic cat models reduced subsequent parental provisioning rates, a strong indicator of sublethal effects, by one-third relative to a nonpredatory rabbit Oryctolagus cuniculus (Linnaeus 1758) control. There was no compensatory increase in food load size. Previous experiments demonstrate that this magnitude of reduced food delivery will reduce nestling growth rates by c. 40%. The grey squirrel model induced similar but weaker effects.

Following the brief presence of the domestic cat model, subsequent daily nest predation rates, chiefly by corvids, increased by an order of magnitude relative to the squirrel and rabbit models. The intensity of parental nest defence elicited in response to model presentations predicts the probability of such third-party predator predation events, and the domestic cat model generated significant increases in nest defence behaviour.

Synthesis and applications

The brief presence of a domestic cat at avian nest sites reduces subsequent provisioning rates and induces lethal trait-mediated indirect effects. We provide the first robust evidence for these latter effects in any avian predator–prey system, although they are likely to be common in many avian assemblages with high predator densities. It is imperative that future assessments of the impact of predatory species on avian prey species take lethal trait-mediated indirect effects into account, as so doing will prevent biased estimates of predator effects and facilitate the design of more effective control strategies. Full mitigation of the sublethal and indirect effects of domestic cats would problematically require permanent indoor housing.

See also this posts

Disturbance of dogs to Wildlife

Lenth, B., R.L. Knight & M.E. Brennan. 2008. The Effects of Dogs on Wildlife Communities. Natural Areas Journal, 28 (3): 218-227

Domestic dogs (Canis familiaris) are frequent visitors to protected areas, but little is known about how they affect wildlife communities. We studied the effects of dogs on wildlife communities by comparing the activity levels of wildlife in areas that prohibited dogs with areas that allowed dogs. We measured wildlife activity on trails and up to 200 m away from trails using five methods: (1) pellet plots, (2) track plates, (3) remote triggered cameras, (4) on-trail scat surveys, and (5) mapping prairie dog (Cynomys ludovicianus) burrow locations. The presence of dogs along recreational trails correlated with altered patterns of habitat utilization by several species. Mule deer (Odocoileus hemionus) activity was significantly lower within 100 m of trails in areas that allowed dogs than in areas that prohibited dogs. Small mammals, including squirrels (Sciurus spp.) and rabbits (Sylvilagus spp.), also exhibited reduced levels of activity within 50 m of trails in areas that allowed dogs when compared with areas without. The density of prairie dog burrows was lower within 25 m of trails in areas that allowed dogs. The presence of dogs also affected carnivore activity. Bobcat (Felis rufus) detections were lower in areas that allowed dogs, and red fox (Vulpes vulpes) detections were higher. These findings have implications for the management of natural areas, particularly those that allow dogs to be off-leash.

New evaluation of cat's kill in US: probably tens of billions kills per year

Loss, S.R., T. Will & P.P. Marra. 2013. The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications 4, 1396 doi:10.1038/ncomms2380

Anthropogenic threats, such as collisions with man-made structures, vehicles, poisoning and predation by domestic pets, combine to kill billions of wildlife annually. Free-ranging domestic cats have been introduced globally and have contributed to multiple wildlife extinctions on islands. The magnitude of mortality they cause in mainland areas remains speculative, with large-scale estimates based on non-systematic analyses and little consideration of scientific data. Here we conduct a systematic review and quantitatively estimate mortality caused by cats in the United States. We estimate that free-ranging domestic cats kill 1.4–3.7 billion birds and 6.9–20.7 billion mammals annually. Un-owned cats, as opposed to owned pets, cause the majority of this mortality. Our findings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals. Scientifically sound conservation and policy intervention is needed to reduce this impact.

See also this entry.


Read more national surveys results on cat predation

Cats killing billions of animals in the US

By Rebecca Morelle
Science reporter, BBC World Service 29 January 2013 

Cats are one of the top threats to US wildlife, killing billions of animals each year, a study suggests. The authors estimate they are responsible for the deaths of between 1.4 and 3.7 billion birds and 6.9-20.7 billion mammals annually.

Writing in Nature Communications, the scientists said stray and feral cats were the worst offenders. However, they added that pet cats also played a role and that owners should do more to reduce their impact.

The authors concluded that more animals are dying at the claws of cats in the United States than in road accidents, collisions with buildings or poisonings. The domestic cat's killer instinct of has been well documented on many islands around the world. Felines accompanying their human companions have gone on to decimate local wildlife, and they have been blamed for the global extinction of 33 species. But their impact on mainland areas has been harder to chart.

To find out more, researchers from the Smithsonian Conservation Biology Institute (SCBI) and the US Fish and Wildlife Service carried out a review of studies that had previously looked at the predatory prowess of cats. Their analysis revealed that the cat killings were much higher than previous studies had suggested: they found that they had killed more than four times as many birds as has been previously estimated.

Birds native to the US, such as the American Robin, were most at risk, and mice, shrews, voles, squirrels and rabbits were the mammals most likely to be killed.

Dr Pete Marra from the SCBI said: "Our study suggests that they are the top threat to US wildlife."

The team said that "un-owned" cats, which they classified as strays, feral cats and farm cats, were killing about three times as many animals as pet cats, but that their owners could do more to limit the impact.

Dr Marra said: "We hope that the large amount of wildlife mortality indicated by our research convinces some cat owners to keep their cats indoors and that it alerts policymakers, wildlife managers and scientists to the large magnitude of wildlife mortality caused by cat predation."

A spokeswoman for the UK's animal welfare charity the RSPCA said that a properly fitted collar and bell could reduce a cat's success when hunting by at least a third.

http://www.bbc.co.uk/news/science-environment-21236690


Read a short review about belling effectiveness

Cats vs. birds in Japan

[PDF] de unh.edu

Takahashi, M. A. (2004). Cats v. Birds in Japan: How to Reconcile Wildlife Conservation and Animal Protection. Geo. Int'l Envtl. L. Rev., 17, 135.

Distribution and spatial genetic structure of wildcat in France

Say, L., S. Devillard, F. Léger, D. Pontier & S. Ruette. 2012. Distribution and spatial genetic structure of European wildcat in France. Animal Conservation , 15 (1): 18-27

Given the problem of hybridization with domestic cats, there is a growing need to identify populations of the European wildcat Felis silvestris silvestris in order to protect the genetic integrity of this subspecies. In this paper, we use known locations of observations of wildcats or recovered carcasses to reassess the distribution of the wildcat in France and, in cases where carcasses were collected, we use both phenotypic and molecular genetic analyses to distinguish wildcats from hybrids with domestic cats. Spatially explicit multivariate analysis of wildcat' genotypes was then performed to define genetic units. Our study confirms the presence of wildcats in a large area of c. 155 000 km² , suggestive of a range of expansion, and divided into two clearly distinct and unconnected areas – the Pyrenees and the north-eastern part of France. However, European wildcat populations may be decreasing in the French Pyrenees, whereas the north-eastern part represents the main area (MA) of wildcat presence. This extension does not appear to be primarily due to hybrids, as both wildcats and hybrids were located throughout the MA. In addition, we found that genetic diversity of wildcats in the MA is remarkably high, suggesting that French populations are not threatened by a lack of genetic diversity. Furthermore, wildcats of the MA are structured into two genetically distinct populations that are contiguous and probably extend into Germany to form the largest area of wildcat presence in Europe and an area of major interest for their conservation. Our study calls for localized examination of the feasibility and usefulness of wildlife corridors to enhance connectivity between the different populations, thereby allowing sufficient levels of immigration and gene flow within the regional meta-population to ensure the long-term viability of these populations.


See more on domestic cat introgression in wildcat

Behaviour changes in urban ecosystems

Ditchkoff, S. S., Saalfeld, S. T., & Gibson, C. J. (2006). Animal behavior in urban ecosystems: modifications due to human-induced stress. Urban Ecosystems, 9(1), 5-12.

Wildlife-human interactions are increasing in prevalence as urban sprawl continues to encroach into rural areas. Once considered to be unsuitable habitat for most wildlife species, urban/suburban areas now host an array of wildlife populations, many of which were previously restricted to rural or pristine habitats. The presence of some wildlife species in close proximity to dense human populations can create conflict, forcing resource managers to address issues relating to urban wildlife. However, evidence suggests that wildlife residing in urban areas may not exhibit the same life history traits as their rural counterparts because of adaptation to human-induced stresses. This creates difficulty for biologists or managers that must address problems associated with urban wildlife. Population control or mitigation efforts aimed at urban wildlife require detailed knowledge of the habits of wildlife populations in urban areas. This paper describes the history of wildlife in urban areas, provides examples of wildlife populations that have modified their behavior as an adaptation to urban stresses, and discusses the challenges that resource managers face when dealing with urban wildlife.

Colonias "controladas" de gatos

En un folleto de la American Bird Conservancy, producido dentro de la campaña Cats Indoors, se repasan los problemas asociados a las colonias de gatos "controlados". En ellas, los gatos callejeros se liberan tras su esterilización. En el folleto, firmado por una docena de organismos incluyendo varios colectivos de veterinarios y de activistas por los derechos de los animales, se comentan los problemas asociados a estas colonias. Entre ellos, la depredación que sigue existiendo sobre la vida silvestre, la posible transmisión de enfermedades a las personas y la falta de control sobre las condiciones de vida de los gatos, que siguen padeciendo crueldad o enfermedades. Además, las colonias atraen a gatos abandonados y sirven de "vertedero" de gatos no deseados.
Sin embargo, por ejemplo, el Ayuntamiento de Barcelona reproduce en su web, un documento técnico de trabajo sobre cómo crear y "controlar" una colonia de gatos vagabundos. En el artículo se recomienda contactar con los posibles colaboradores, y luego menciona los aspectos técnicos de la gestión de la colonia. No menciona ni por un momento la palabra "ave" o "depredación".
La información sobre las colonias controladas de gatos es enorme. Alley Cat Allies, por ejemplo, es una organización bien documentada y que tiende a argumentar su postura con criterios. Así, se oponen a los estudios sobre depredación realizada sobre aves y otra fauna silvestre apoyándose en que la extrapolación de los resultados no es realista y que las amenazas sobre las aves son otras. Así, por ejemplo, el artículo sobre el mímido gris que atribuye a los gatos la mayor parte de las bajas conocidas es criticado por extrapolar las causas conocidas de mortalidad al total. Sitios muy activos como Vox Felina, critican intensamente y de forma bastante documentada, los artículos publicados sobre el impacto de los gatos en la biodiversidad. En general, las críticas suelen caer en la ridiculización de los aspectos no tratados por un trabajo o en una caricaturización del método, así como en una demonización de la estadística como herramienta de fabricación de datos a medida. Si bien es cierto que las extrapolaciones son arriesgadas, las críticas simplemente intentan demostrar que la depredación es anecdótica, sin tener en cuenta la enorme cantidad de depredadores domésticos o errantes que constituyen, en su conjunto una presión considerable, si bien no la única, sobre los pequeños vertebrados silvestres. El debate tiene demasiados componentes emocionales (por ambas partes, todo hay que reconocerlo). 

Loss of wildlife to domestic cats

Paton, D. (1991). Loss of wildlife to domestic cats. In Potter, C. (ed), The Impact of Cats on Native Wildlife: Proceedings of a Workshop held on May 8-9 1991. ANPWS, Canberra

Questionnaires asked people how many animals they thought their cat(s) had killed in the previous 12 months. Of the 3000 questionnaires distributed, 709 were returned, covering 700 cats in Adelaide suburbs, in country towns and in rural areas. The majority of the questionnaires (88%) came from members of birders' associations.

• Cats in rural areas were reported to catch over twice as many prey as suburban cats. 
• The average number of prey reported caught per year was 30. 
• Suburban cats (the majority of cats) were reported to catch less, and rural cats (far fewer in number) caught more. 
• Bells were ineffective 
• Most preys were non native

Stable isotopes to know cat's diet on islands

MECKSTROTH, A. M., MILES, A. K. & CHANDRA, S. 2007. Diets of Introduced Predators Using Stable Isotopes and Stomach Contents. The Journal of Wildlife Management, 71: 2387–2392.

In a study of predation on ground-nesting birds at South San Francisco Bay (South Bay), California, USA, we analyzed stomach contents and stable isotopes of carbon and nitrogen to identify commonly consumed prey. We obtained the stomach contents from 206 nonnative red foxes (Vulpes vulpes regalis) collected in the South Bay area and Monterey County during 1995–2001 and from 68 feral cats (Felis silvestris) from the South Bay area during 2001–2002. We determined prey identity, biomass, and frequency, described seasonal diet trends, and derived an Index of Relative Importance. Avian species were the most frequent prey we found in the stomachs of red foxes from South Bay (61%), whereas small rodents were most frequent for red foxes from Monterey County (62%). Small rodents were the most frequent prey we found in feral cats (63%). Carbon and nitrogen isotopic signatures for foxes supported stomach content findings. However, isotope results indicated that cats received a majority of their energy from a source other than rodents and outside the natural system, which differed from the stomach content analysis. We demonstrated the utility of both stable isotope and stomach content analyses to establish a more complete understanding of predators' diets. This information aids natural resource managers in planning and evaluating future predator-removal programs and increases our understanding of the impacts of nonnative foxes and cats on native species.



Petra Quillfeldt, P.,  I. Schenk, R.A. R. McGill, I. J. Strange, J.F. Masello, A. Gladbach, V. Roesch & R.W. Furness. 2008.Introduced mammals coexist with seabirds at New Island, Falkland Islands: abundance, habitat preferences, and stable isotope analysis of diet. Polar Biology 31:333–349 

The largest known colony of Thin-billed prions Pachyptila belcheri has been coexisting with introduced mammals for more than 100 years. Three of the introduced mammals are potential predators of adults, eggs and chicks, namely ship rats Rattus rattus, house mice Mus musculus and feral cats Felis catus. We here determine habitat preferences over three seasons and dietary patterns of the unique set of introduced predators at New Island, Falkland Islands, with emphasis on the ship rats. Our study highlights spatial
and temporal diVerences in the levels of interaction between predators and native seabirds. Rats and mice had a preference for areas providing cover in the form of the native tussac grass  Parodiochloa  xabellata or introduced gorse  Ulex europaeus. Their diet differed markedly between areas, over the season and between age groups in rats. During the incubation period of the prions in November–December, ship rats had mixed diets, composed mainly of plants and mammals, while only 3% of rats had ingested birds. The proportion of ingested birds, including scavenged, increased in the prion chick-rearing period, when 60% of the rats consumed prions. We used 13C and 15N to compare the importance of marine-derived food between mammal species and individuals, and found that rats in all but one area took diet of partly marine origin, prions being the most frequently encountered marine food. Most house mice at New Island mainly had terrestrial diet. The stable isotope analysis of tissues with different turnover times indicated that individual rats and mice were consistent in their diet over weeks, but opportunistic in the short term. Some individuals (12% of rats and 7% of mice) were highly specialized in marine-derived food. According to the isotope  ratios in a small sample of cat faeces, rodents and rabbits were the chief prey of cats at New Island. Although some individuals of all three predators supplement their terrestrial diet with marine-derived food, the current impact of predation by mammals on the large population of Thinbilled prions at New Island appears small due to a number of factors, including the small size of rodent populations and restriction mainly to small areas providing cover.

Diet of cats on islands

Bonnaud, E., F. M. Medina, E. Vidal, M. Nogales, B. Tershy, E. Zavaleta, C. J. Donlan,  B. Keitt, M. Le Corre & S. V. Horwath. 2011. The diet of feral cats on islands: a review and a call for more studies. Biological Invasions, 13: 581–603.

Cats are among the most successful and damaging invaders on islands and a significant driver of extinction and endangerment. Better understanding of their ecology can improve effective management actions such as eradication. We reviewed 72 studies of insular feral cat diet from 40 islands worldwide. Cats fed on a wide range of species from large birds and medium sized mammals to small insects with at least 248 species consumed (27 mammals, 113 birds, 34 reptiles, 3 amphibians, 2 fish and 69 invertebrates).
Three mammals, 29 birds and 3 reptiles recorded in the diet of cats are listed as threatened by the IUCN.
However, a few species of introduced mammals were the most frequent prey, and on almost all islands mammals and birds contributed most of the daily food intake. Latitude was positively correlated with the predation of rabbits and negatively with the predation of reptiles and invertebrates. Distance from landmass was positively correlated with predation on birds and negatively correlated with the predation of reptiles.
The broad range of taxa consumed by feral cats on islands suggests that they have the potential to impact almost any native species, even the smallest ones under several grams, that lack behavioral, morphological or life history adaptations to mammalian predators. Insular feral cat’s reliance on introduced mammals, which evolved with cat predation, suggests that on many islands, populations of native species have already been reduced.

Impact of cats on islands endangered vertebrates

Medina, F.M., E. Bonnaud, E. Vidal, B. Tershy, E.S. Zavaleta, C. J. Donlan, B.S . Keitt, M. Le Corre, S.V. Horwath & M. Nogales. 2011. A global review of the impacts of invasive cats on island endangered vertebrates.Global Change Biology, 17, 3503–3510


Cats are generalist predators that have been widely introduced to the world’s ~179 000 islands. Once introduced to islands, cats prey on a variety of native species many of which lack evolved defenses against mammalian predators and can suffer severe population declines and even extinction. As islands house a disproportionate share of terrestrial biodiversity, the impacts of invasive cats on islands may have significant biodiversity impacts. Much of this threatened biodiversity can be protected by eradicating cats from islands. Information on the relative impacts of cats on different native species in different types of island ecosystems can increase the efficiency of this conservation tool. We reviewed feral cat impacts on native island vertebrates. Impacts of feral cats on vertebrates have been reported from at least 120 different islands on at least 175 vertebrates (25 reptiles, 123 birds, and 27 mammals), many of which are listed by the International Union for the Conservation of Nature. A meta-analysis suggests that cat impacts were greatest on endemic species, particularly mammals and greater when non-native prey species were also introduced. Feral cats on islands are responsible for at least 14% global bird, mammal, and reptile extinctions and are the principal threat to almost 8% of critically endangered birds, mammals, and reptiles.

Wildlife response to dogs

Miller, S.G., Knight, R.L. & Miller, C.K. 2001. Wildlife responses to pedestrians and dogs. Wildlife Society Bulletin, 29 (1): 124-132.

You can download here the homonimous report from 1996 

As participation in outdoor recreational activities escalates, land managers struggle to develop management policies that ensure coexistence of wildlife and recreation. However, this requires an understanding of how wildlife responds to various forms of recreational activities and the spatial context in which the activities occur. Therefore, we measured responses of 2 species of grassland songbirds, one species of forest songbird, and mule deer (Odocoileus hemionus) exposed to a pedestrian, a pedestrian accompanied by a dog on leash, and a dog alone (only for grassland birds), on and away from recreational trails. We assessed the "area of influence" for each treatment by determining the probability that an animal would flush or become alert (for mule deer only) given its perpendicular distance to a trail or a line of movement in areas without trails. When animals were disturbed, we measured flush distance (the distance between the disturbance and the animal when flushed), distance moved, and, for mule deer, alert distance (the distance between the disturbance and the deer when it became alert). For all species, area of influence, flush distance, distance moved, and alert distance (for mule deer) was greater when activities occurred off-trail versus on-trail. Generally, among on-trail and off-trail treatments in grasslands for vesper sparrows (Pooecetes gramineus) and western meadowlarks (Sturnella neglecta), the smallest area of influence and shortest flush distance and distance moved resulted from the dog-alone treatment, and these responses were greater for the pedestrian-alone and dog-on-leash treatments. In forests, for American robins (Turdus migratorius), the area of influence, flush distance, and distance moved did not generally differ between the pedestrian-alone and dog-on-leash treatments. For mule deer, presence of a dog resulted in a greater area of influence, alert and flush distance, and distance moved than when a pedestrian was alone. Natural lands managers can implement spatial and behavioral restrictions in visitor management to reduce disturbance by recreational activities on wildlife. Restrictions on types of activities allowed in some areas such as prohibiting dogs or restricting use to trails will aid in minimizing disturbance. Additionally, managers can restrict the number and spatial arrangement of trails so that sensitive areas or habitats are avoided.

Predation on NZ shorebirds

Dowding, J. E., & Murphy, E. C. (2001). The impact of predation by introduced mammals on endemic shorebirds in New Zealand: a conservation perspective.Biological Conservation, 99(1), 47-64.

The avifauna of New Zealand has been severely depleted since human colonisation and currently contains a disproportionately high number of threatened species. Of the 23 threatened shorebird species worldwide, six are endemic to New Zealand. We review the status of New Zealand's endemic shorebirds and examine the impact on them of various threats, particularly predation by introduced mammals. The conservation status of the 10 extant species (three oystercatchers, one stilt, four plovers and two snipe) is outlined and the factors that predisposed them to predation by introduced mammals are summarised. Individual species accounts are presented, including data on population trends, known or suspected impacts of predation, identification of important predator species, other threats, and conservation measures currently in place or required. One species and two subspecies are extinct, three species are confined to predator-free islands and another is found only on the Chatham Islands group. Six survive on the mainland but three have declined to varying degrees and are assigned threatened status by Collar et al. (1994). Only one plover and two oystercatchers are still relatively numerous and/or widespread. Rats, cats and mustelids have had the greatest overall impacts. Conservation measures in place to mitigate the effects of introduced predators include the formulation of recovery plans, predator control around breeding areas, captive breeding and rearing programmes and the founding of new populations by translocation. There are often substantial differences in susceptibility to predation of closely related or ecologically similar taxa, and we stress the importance of basing conservation management decisions on relevant and detailed demographic and ecological studies. The main threat to threatened shorebirds elsewhere in the world is loss or degradation of habitat; the disproportionate impact of mammalian predators on New Zealand shorebirds is unusual but not unique.

Cats Indoors!

Cats Indoors! The Campaign for Safer Birds and Cats, was initiated by the American Bird Conservancy (ABC) to end the unnecessary suffering and death of birds and other wildlife caused by free-roaming domestic cats. Cats Indoors! seeks to educate cat owners, decision makers and the general public that free-roaming cats pose a significant risk to birds and other wildlife, suffer themselves, and pose a threat to human health.

 

Cats Indoors! encourages cat owners to keep their cats indoors and advocates laws, regulations, and policies to protect cats and birds, including the humane removal of free-roaming cats from areas important to wildlife. The campaign promotes grassroots efforts to address the issue at state and local levels.

Urban dogs as a source of virus for wild carnivores

Acosta-Jamett, G., Cleaveland, S., Cunningham, A. A., & Bronsvoort, B. M. D. (2010). Demography of domestic dogs in rural and urban areas of the Coquimbo region of Chile and implications for disease transmission. Preventive veterinary medicine, 94(3), 272-281.

A cross-sectional household questionnaire survey was conducted along two transects (80 and 45 km long) from Coquimbo and Ovalle cities to the Fray Jorge National Park (FJNP) in the Coquimbo region of Chile in 2005–2007 to investigate the demography of dogs in the context of a study of canine infectious diseases. Data were collected on the number of dogs per household, fecundity, mortality, and sex and age distribution. The results from 1021 households indicated that dog ownership was common, with a higher proportion of households owning dogs in rural areas (89%), than in towns (63%) or cities (49%). Dog density ranged from 1380 ± 183 to 1509 ± 972 dogs km^-2 in cities, from 119 ± 18 to 1544 ± 172 dogs km^-2 in towns, and from 1.0 ± 0.4 to 15.9 ± 0.4 dogs km^-2 in rural sites. The dog population was estimated to be growing at 20% in cities, 19% in towns and 9% in rural areas. The human:dog ratio ranged from 5.2 to 6.2 in cities, from 2.3 to 5.3 in towns, and from 1.1 to 2.1 in rural areas. A high percentage of owned dogs was always allowed to roam freely in the different areas (27%, 50% and 67% in cities, towns and rural areas, respectively). Observations of free-roaming dogs of unknown owner were reported from a greater proportion of respondents in cities (74%), followed by towns (51%) and finally by rural areas (21%). Overall only 3% of dogs had been castrated. In addition, only 29% of dogs were reported to have been vaccinated against canine distemper virus (CDV) and 30% against canine parvovirus (CPV). The higher population size and density, higher growth rate and a higher turnover of domestic dogs in urban than in rural areas and the poorly supervised and inadequately vaccinated dog populations in urban areas suggest that urban areas are more likely to provide suitable conditions for dogs to acts as reservoirs of pathogenic infections.

Acosta-Jamett, G., Chalmers, W. S. K., Cunningham, A. A., Cleaveland, S., Handel, I. G., & Bronsvoort, B. M. (2011). Urban domestic dog populations as a source of canine distemper virus for wild carnivores in the Coquimbo region of Chile. Veterinary microbiology, 152(3), 247-257.

Urban areas can support dog populations dense enough to maintain canine distemper virus (CDV) and can be a source of infection for rural dogs and free-ranging carnivores. The aim of this study was to investigate the relationships between urban and rural domestic dog and wild carnivore populations and their effects on the epidemiology of CDV to explain retrospectively a CD outbreak in wild foxes in 2003. From 2005 to 2007 a cross-sectional household questionnaire survey was conducted in Coquimbo and Ovalle cities, in three towns and in rural sites along two transects from these cities to the Fray Jorge National Park (FJNP) in the Coquimbo region, Chile. Blood samples were collected from unvaccinated dogs at surveyed households and from free-ranging foxes in rural areas along the transects. The seroprevalence of CDV in domestic dogs was higher in urban than in rural areas and in the later was highest in dogs born before 2001–2002. The seroprevalence of CDV in foxes was higher in areas closer to human settlements. A high seroprevalence in dogs born before 2001–2002 further supports a link between CDV patterns in rural dog and fox populations. In our study area, urban dogs are proposed to be the source of CDV infection to wild carnivores. The large dog population size and density detected in Coquimbo and Ovalle provides optimal conditions for maintaining a large and dense susceptible population of dogs, which can act as a reservoir for highly infectious diseases and could have been the source of infection in the CD outbreak in wild foxes.

Survey on metropolitan domestic cats

Millwood, J. & T. Heaton 1994. The Metropolitan Domestic Cat. Petcare Information and Advisory Service, Melbourne. UAM Conference Proceedings - Canberra 1994

BACKGROUND 

In Australia in recent years, concern has been raised about the possible impact of cats, both domestic and feral, on native fauna populations. 

Concern about the role of domestics cats in particular has led some groups to consider cat management options. 

Management decisions are hampered, however, by a scarcity of scientific information on the interaction of domestic cats with native fauna.

Previous research has shown that domestic cats are catching native wildlife. But - how many? To date, none of the studies published have used sample groups which reflect domestic cat distribution, making it very difficult to draw conclusions about the behaviour of the cat population as a whole. 

Most people live in highly urbanised areas. It was suspected that a survey conducted over the full range of 

metropolitan populations would show that domestic cats in fact catch very few native fauna. 

Petcare Information and Advisory Service (PIAS) thus commissioned Reark Research Pty Ltd, an independent market research organisation, to conduct a detailed survey of the metropolitan cat in all Australian capital cities (except Darwin). The sample group was selected to represent domestic cat distribution within each city, thus ensuring that conclusions could be drawn about the metropolitan cat population. 

The survey was to provide information on the hunting behaviour of domestic cats and determine the size, age and neuter status of the metropolitan cat population. 

OBJECTIVES 

1. To clarify the hunting behaviour of the metropolitan domestic cat, including: 

• What creatures are caught; 
• How many creatures are caught; 
• How many native creatures are caught. 

2. To provide detailed information on the metropolitan cat population, including: 

• what percentage are desexed; 
• changes in cat population over the last 12 months

3. To provide information on factors likely to effect cat hunting behaviour, including: 

• confinement of cats by the owner to the property at night; 
• tendency of cats to roam from the owner's property; 
• wearing bells. 

SURVEY METHODOLOGY 

The survey was designed to provide complete coverage of the cat population within metropolitan Australia, covering the entire Statistical Division for each of the capital cities. 

The metropolitan region included within the scope of the survey covers 62.7 percent of the private dwellings 

throughout the whole of Australia. Within each city, sample selection was controlled to appropriately represent population distribution, and results were weighted accordingly. 

A systematic probability sample of telephone 'white page directory' listings within postcodes classified as 'relatively low' to 'high' population densities was generated. 

Over 4000 households were surveyed. The size of the sample group ensured that the maximum degree of error was limited to not more than + /-2 percent for all estimates relating to the total metropolitan domestic cat population. 

The questionnaire was sequenced to establish a rapport between interviewer and subject, and invite an open and non threatening discussion of the cat's behaviour, thus reducing possible bias due to recent media coverage of 'cat issues'. 

RESULTS 

1. Hunting Behaviour

The proportion of domestic cats which caught prey.

• 41 percent of cats caught introduced mammals such as mice, rats and rabbits (vermin), and 2 percent caught native mammals such as possums or bats. 
• 17 percent of cats caught reptiles or amphibians such as lizards, skunks, snakes or frogs. 
• 19 percent of cats caught introduced birds such as sparrows and starlings, and 7 percent caught native birds such as magpies or honey eaters. 

Overall, 56 percent of cats were reported to catch prey. (Note that as cats could catch more than one type of creature, the total number of cats catching prey is less than the sum of cats catching individual creatures) 

The number of prey caught by domestic cats

Over the period 12 months to April 1994, native species were 33% of metropolitan domestic cats caughts.

2. Domestic cat population

• Almost one million households (985 000), that is 25.2 percent of households throughout the capital cities of Australia own a cat. 
• The total number of cats living within those households is estimated as 1,397,000. 
• Fewer households own cats than a year ago, and the number of cats per cat owning household has also dropped. 
• In the past twelve months there has been a 10 percent decline in the metropolitan cat population. 

3. Factors likely to affect cat hunting behaviour

• 39 percent of the cat population was securely contained at night. 
• 79 percent of the cat population was reported to not roam away from the home surrounds during the day. 
• The proportion of cats which caught any creature was lower for those cats which were confined to the house at night, than those which were allowed out. 
• The proportion of cats which caught any creature was higher for those which wore bell collars than those which did not.

CONCLUSIONS 

The findings support the suspicion that metropolitan domestic cats are in fact catching substantially fewer native fauna than previously supposed. 

During the survey year, each domestic cat is estimated to have caught on average: 

• One fiftieth of a native mammal; 
• One fifth of a native bird; 
• One and a third native reptiles or amphibians; 
• Half of all creatures caught were vermin - mice, rats and rabbits. 

Contrary to common perceptions that cat numbers are increasing, it appears the metropolitan domestic cat population is in decline.

• The metropolitan domestic cat population decreased by 10 percent over April 1993-1994. 
• The vast majority (94 percent) of adult metropolitan domestic cats are desexed. 

Bell collars do not appear to be effective in preventing hunting, although conclusions are difficult to draw as owners are more likely to place bells on cats which are proven hunters. 

Those cats which spend most of their time around the home tend to hunt less.


Read a short review about belling effectiveness

Dog attacks to sheep

Jennens, G. 2002. Domestic dog attacks on sheep in the urban fringe areas of Perth, Western Australia. PhD thesis, Murdoch University.

In common with many cities, Perth, Western Australia has a problem with domestic dogs attacking livestock, such as sheep on its urban fringe areas. The current study used multiple sources to document 1479 attacks on livestock on 1105 properties by 1900 dogs across eight metropolitan local authorities over a three-year period. The hypothesis that dog attacks on sheep are poorly understood by the community and continue as a result of inaction by local authorities, dog owners and livestock owners, rather than being an unavoidable predator/prey interaction, was supported. The predatory behaviour of domestic dogs and the anti-predatory behaviour of sheep were observed to be similar to that of wild canids and ungulates respectively.

The reluctance of local authorities to prosecute offenders and enforce by-laws meant that there was little voluntary compliance by dog owners to control their dogs. It therefore, became necessary for livestock owners to protect their livestock; however, most failed to take effective preventive measures.

Wild canids predominantly attack the head and neck of prey animals, whereas in contrast, domestic dogs may attack any part of a sheep. Examination of injury sites, in conjunction with information collected from other investigative techniques, assisted with the identification of the breed, size and number of dogs responsible. To overcome difficulties in locating a dog not sighted attacking, tracker-dogs were trained to follow the attacker's scent back to its home. The majority of dogs (60%) lived within 200 metres of the livestock they attacked and used the same route to and from the property on subsequent attacks.

A single or pair of owned dogs from the same household, belonging to 14 breeds were primarily responsible for attacks. Poor management by dog owners on inadequately fenced smallholdings enabled these dogs to wander unnoticed from their properties. Although most dog owners accepted evidence of their dogs' involvement, few accepted blame and most were surprised that their "friendly" pet could attack livestock. Unless dogs were destroyed, relocated or contained by their owners they were likely to attack again.

It is concluded that dog attacks occur commonly in urban fringe areas; however, with appropriate management of dogs and livestock these can be minimised.

Canine virus impact on island fox

Clifford, D.L., J.A.K. Mazet, E.J. Dubovi, D.K. Garcelon, T.J. Coonan, P. A. Conrad & L. Munson. 2006. Pathogen exposure in endangered island fox (Urocyon littoralis) populations: Implications for conservation management. Biological Conservation, 131: 230 – 243

Island fox (Urocyon littoralis) populations on four California Channel Islands have declined severely since 1994. Canine distemper (CDV) was suspected to be responsible for the decline of the Santa Catalina Island fox, so knowledge of infectious disease exposure in the remaining island fox populations was urgently needed. This study reviewed previous pathogen exposure in island foxes and investigated the current threat by conducting a serologic survey of foxes on all islands and sympatric feral cats on three islands from 2001 to 2003 for antibodies against canid pathogens. Before the decline, foxes had evidence of exposure to CDV, canine adenovirus (CAV), canine parvovirus (CPV), and Toxoplasma, with exposure to these five pathogens differing greatly by island. Exposure to canine coronavirus (CCV), canine herpesvirus (CHV), and Leptospira was rare. In 2001–2003, wild-born foxes had evidence of exposure to CDV (5.2–32.8%) on 5 of 6 islands, CPV (28–100%) and CAV (4.7–100%) on five islands, and Toxoplasma gondii (2.3–15.4%) on four islands. Exposure to CCV, CHV and Leptospira was less common. Sharing of infectious agents between sympatric foxes and feral cats appeared minimal, but CDV exposure was detected in two cats on Santa Catalina Island. Domestic dogs have historically been present on the islands, but it is not known if canine diseases can be maintained in fox populations without the continual presence of dogs. Targeted vaccination programs against the most virulent pathogens and continued intensive disease surveillance may help protect the critically small remaining fox population

Dogs prefer poo to rodents, so few competition for Ethiopian wolf

Atickem A., A. Bekele & S.D. William. 2009. Competition between domestic dogs and Ethiopian wolves (Canis simensis) in the Bale Mountains National Park, Ethiopia. African Journal of Ecology, 48: 401–407.

The potential effects of the domestic dogs (Canis familiaris) on the Endangered Ethiopian wolf (Canis simensis) through exploitative and interference competition were studied in the Web Valley of Bale Mountains national park between November 2001 and February 2003. All dogs were owned in the study area and no feral dogs were reported or observed during the research period. The diet of domestic dogs was dominated by barley husks and human faeces which contributed 45% and 20.7% of the total 382 meals observed during focal watch observations. Analysis of dog faeces provided similar results with barley husks, human faeces and animal carcasses occurring in 86.8%, 21.4% and 19.4% of the 1200 faecal samples analysed. Both focal watch and faecal analyses revealed that rodents contributed only a very small proportion of the diet of dogs accounting for only 4.2% of the focal watch and 2.8% of the faecal analysis of roaming dogs. As Ethiopian wolves fed almost exclusively on rodent year round, no significant exploitative competition between dogs and wolves were assessed. Only small proportion of the domestic dogs roamed in the Ethiopian wolf range and interference competition did not appear to be a serious threat for the Ethiopian wolf.

Impact of feral and free roaming dogs on Wildlife: review and study case in Mongolia

Young, J.K, K. A. Olson, R.P. Reading, S. Amgalanbaatar & J. Berger. 2011. Is Wildlife Going to the Dogs? Impacts of Feral and Free-roaming Dogs on Wildlife Populations. BioScience, 61(2):125-132.

In human-populated landscapes, dogs (Canis familiaris) are often the most abundant terrestrial carnivore. However, dogs can significantly disrupt or modify intact ecosystems well beyond the areas occupied by people. Few studies have directly quantified the environmental or economic effects of free-roaming and feral dogs. Here, we review wildlife-dog interactions and provide a case study that focuses on interactions documented from our research in Mongolia to underscore the need for studies designed to best determine how dogs affect native wildlife and especially imperiled populations. We suggest additional research, public awareness campaigns, and the exclusion of dogs from critical wildlife habitat. The application of scientific findings to management and enhanced public outreach programs will not only facilitate recovery and maintenance of wildlife populations globally but also has the potential to reduce economic losses.

Effect of cats being fed on parks' wildlife

Hawkins, C.C., W.E. Grant & M.T. Longnecker. 2004. Effect of house cats, being fed in parks, on California birds and rodents. . In: Shaw et al.,(eds) Proceedings 4th International Urban Wildlife Symposium:   164-170.

Increasingly, cat (Felis catus) advocates are establishing feeding stations or cat colonies in public parks and often claim that the well-fed cats pose little threat to wildlife populations. This claim was tested on East Bay Regional Park District land east of San Francisco, California during 1995 and 1996. Rodents were livetrapped on 100-trap grids for 8 nights at 9 sites (5 in 1995) in a no cat area and 9 sites (5 in 1995) in a cat area. Bird surveys, 6 in each area in 1995 and 8 in each area in 1996, were conducted along 2.2km transects. The number of cats seen in the 2 areas differed both years (P<0.0001). In 1995, more harvest mice (Reithrodontomys megalotis) were trapped in the no cat area (P=0.022) whereas the numbers of deer mice (Peromyscus sp.) (P=0.207), house mice (Mus musculus) (P=0.257), and California voles (Microtus californicus) (P=0.362) trapped were not different in the cat and no cat areas. In 1996, more harvest mice (P=0.0003) and deer mice (P=0.019) were trapped in the no cat area, more house mice (Mus musculus) were trapped in the cat area (P=0.008), and the numbers of California meadow voles (P=0.838) trapped were not different between areas. More native rodents were trapped in the no cat area both years, 1995 (P=0.033), 1996 (P=0.005). Over 85% of the deer mice and the harvest mice trapped occurred in the no cat area and 79% of the house mice trapped were in the cat area. Birds that were resident year-round were seen more often in the no cat area(P=0.009). California quail (Callipepla californicus) (P <0.0001) and California thrashers (Toxostoma redivivum) (P=0.002) were more likely to be seen on a survey in the no cat area than in the cat area.

Urban stray cats' spatial behaviour

Steen-Ash, S. 2004. Intraspecific spatial dynamics of urban stray cats. In: Shaw et al.,(eds) Proceedings 4th International Urban Wildlife Symposium: 222-227

Supporters of the TTVAR (trap-test-vaccinate-alter-release) approach for the control of stray cat populations assume that a group of cats sharing a common food source will defend their space and resources from immigrating individuals. Previous studies have indicated that group- living domestic cats exhibit a high degree of home range overlap, associate frequently and amicably with group members, and defend their resources against immigrating individuals. This study was designed to examine the spatial relationships among cats managed with the TTVAR method on the Texas A&M University campus. Specific objectives of this study include quantifying individual home ranges and examining the spatial overlap and degree of association between individuals.
Nineteen cats from 6 sites were fitted with radiocollars in September and October 1998, and 11 cats from 5 sites were fitted with radiocollars in January and February 1999. Males ranged an average area of 15.2 ha. The mean female home range size was 12.8 ha. No significant difference was found in home range size between males and females (P< 0.3244, Mann-Whitney U). In all 6 sites, cats exhibited a high degree of home range overlap; however, only 15 individuals were found to associate with other cats. The majority of associating pairs of individuals were found together infrequently. The findings of this study suggest that most cats living on the Texas A&M University campus do not exhibit the same spatial dynamics as expected from colonies of individuals sharing a common food source. Behaviors common to cats living in cohesive groups were observed in this population of cats only occasionally. Consequently, the assumption of resource defense by individuals sharing a common feeding area may not fully apply for this population of stray cats.

One more review on cat's impacts on wildlife

Brickner, I. 2003. The impact of domestic cat (Felis catus) on wildlife welfare and conservation: a literature review with a situation summary from Israel. Tel Aviv University report.

Reviews dozens of articles on cat impact on wildlife. After discussin the role of domestic cats as predators, the author reviews predation impact and choice of preys around the world, as well as the indirect impact of predation by domestic cats. The document also discusses hybridization problems, diseases transmition, to wildlife and to humans. There's also a review of spatial and social organisation and demographic parameters of domestic cats. The last chapters discuss moral issues and management measures.

A review of the interactions between free-roaming domestic dogs and wildlife

Hughes, J. & D.W. Macdonald. 2013. A review of the interactions between free-roaming domestic dogs and wildlife. Biological Conservation, 157: 341–351

Negative impacts from the presence of domestic animals pose particular issues for biodiversity conservation as they are intimately tied to the economic, social and political values of local people, requiring interdisciplinary cooperation for successful outcomes. Despite domestic dogs being widespread there is little information on the scale and scope of any conservation problems they may cause. Dog management is already carried out by human health and welfare groups in order to improve welfare and reduce disease spread, primarily rabies. By reviewing information about interactions between dogs and wildlife, this paper aims to provide a clear summary of current knowledge and facilitate interdisciplinary collaboration between conservation biologists and other experts.

Data from dog population and human population studies indicate that the global domestic dog population abundance is over 700 million. Studies on interactions between free-roaming dogs and wildlife were gathered from searches of seven online databases and other sources. In total, 69 peer-reviewed studies were found. The wildlife taxon mainly studied was mammals (78%) and the main interaction recorded was predation by domestic dogs, followed by disease transmission, wildlife disturbance, hybridization and predation of dogs by wild carnivores. Conservation issues with domestic dogs were recorded from around the world, both on islands and continents. Suggestions of solutions were limited, or not offered, beyond extermination which, given the close relationship between local people and dogs, may not often be appropriate. We propose some steps that will aid cooperation between conservationists and other sectors and enhance the effectiveness of conservation activities.

Highlights

► Domestic dogs Canis familiaris are a globally abundant domestic carnivore.
► We review documented interactions between wildlife and free-roaming domestic dogs.
► Globally, free-roaming dogs cause issues for species conservation and human health.
► Dogs negatively interact with wildlife, mainly by predation and disease spread.
► Interdisciplinary collaboration between experts is needed for effective solutions.

Abstracts of the First Conference on Dog Population Management

Book of Abstracts of the 1st Conference on Dog Population Management, held in York (UK) in September 2012. 
Contains the abstract of 67 oral communications and 17 posters on dog fertility control, zoonoses and conservation problems. Motsly focused on human-dog interactions and attitudes, provides many management tools and solutions.

Libro de resúmenes de la primera conferencia sobre manejo de poblaciones de perros, celebrada en York (Reino Unido) en Septiembre de 2012. 
Contiene el resumen de 67 comunicaciones orales y 17 pósteres sobre control de fertilidad, problemas de zoonosis y de interacción con fauna salvaje. Aunque muy focalizado en la relación humano-perro, facilita diversas herramientas de manejo.

Rabies vaccination in rural Tanzania

Cleaveland, S., M. Kaare, P. Tiringa, T. Mlengeya & J. Barrat. 2003. A dog rabies vaccination campaign in rural Africa: impact on the incidence of dog rabies and human dog-bite injuries. Vaccine, 21: 1965–1973

Despite the availability of safe and effective rabies vaccines, the incidence of dog rabies has been increasing throughout much of sub-Saharan Africa. Here we describe a vaccination strategy that has resulted in successful control of rabies in a rural dog population of Northwestern Tanzania. From October 1996 to February 2001, four central-point dog vaccination campaigns were conducted in villages within Serengeti District with a mean interval between campaigns of 338, 319 and 456 days. Vaccination coverage of the dog population was estimated from household questionnaires as 64.5, 61.1, 70.6 and 73.7% following each of the four campaigns, respectively. The incidence of dog rabies declined significantly in Serengeti District falling by 70% after the first campaign and by 97% after the second campaign. Over the same period, the incidence of dog rabies did not differ significantly in unvaccinated control villages of Musoma District. The incidence
of human bite injuries from suspected rabid dogs declined significantly in Serengeti District after dog vaccination but not in adjacent unvaccinated districts. Vaccination of 60–70% of dogs has been sufficient to control dog rabies in this area and to significantly reduce demand for human post-exposure rabies treatment. Dog-bite injuries can provide a valuable and accessible source of data for surveillance in countries where case incidence data are difficult to obtain.

Demography of a common urban bird

Balogh, A.L., T.B. Ryder & P. P. Marra. 2011. Population demography of Gray Catbirds in the suburban matrix: sources, sinks and domestic cats. Journal of Ornithology, DOI 10.1007/s10336-011-0648-7

Understanding factors that limit the productivity and survival of birds in rapidly changing human-dominated landscapes are key to managing future population persistence. To date, few studies have quantified both nest
success and post-fledging survival for birds breeding within the suburban matrix. Here, we estimated nest success and juvenile post-fledging survival for Gray Catbirds (Dumetella carolinensis) and used those site-specific parameters to model source–sink dynamics at three sites in suburban Washington DC (USA). Cumulative nest success probability varied substantially among suburban sites and indicated that in some cases suburban habitats may provide suitable breeding sites for passerine birds. In addition, we documented the effects of sex and brood size on post-fledging survival rates and determined the role of predation on dispersing fledglings. Like nest success, estimates of post-fledging juvenile survival also varied among sites and highlight the importance of site-specific demographic estimates in urban habitats. Predation accounted for 79% of all mortalities, with 47% of known predation events attributable to domestic cats (Felis catus). Our models of source–sink dynamics underscore the importance of seasonal recruitment parameters for calculating population growth rate and subsequent persistence. This study provides parameter estimates for two critical life history stages in the avian annual cycle in the suburban matrix and posits that predation drives differential nest and post-fledging survival within human-dominated environments.

Rabies in India

M.K. Sudarshan, S.N. Madhusudana, B.J. Mahendra, N.S.N. Rao, D.H. Ashwath Narayana, S. Abdul Rahman, F.-X. Meslin, D. Lobo, K. Ravikumar & Gangaboraiah. 2007. Assessing the burden of human rabies in India: results of a national multi-center epidemiological survey. International Journal of Infectious Diseases, 11, 29—35


Objective: Human rabies has been endemic in India since time immemorial, and the true incidence of the disease and nationwide epidemiological factors have never been studied. The main objectives of the present study were to estimate the annual incidence of human rabies in India based on a community survey and to describe its salient epidemiological features.
Methods: The Association for Prevention and Control of Rabies in India (APCRI) conducted a national multi-center survey with the help of 21 medical schools during the period February-August 2003. This community-based survey covered a representative population of 10.8 million in mainland India. Hospital-based data were also obtained from the 22 infectious diseases hospitals.
A separate survey of the islands of Andaman, Nicobar, and Lakshadweep, reported to be free from rabies, was also undertaken.
Results: The annual incidence of human rabies was estimated to be 17 137 (95% CI 14 109-20 165). Based on expert group advice, an additional 20% was added to this to include paralytic/atypical forms of rabies, providing an estimate of 20 565 or about 2 per 100 000 population. The majority of the victims were male, adult, from rural areas, and unvaccinated. The main animals responsible for bites were dogs (96.2%), most of which were stray. The most common bite sites were the extremities. The disease incubation period ranged from two weeks to six months.

Rabies in Tanzania / Rabia en Tanzania

Cleaveland,S., E.M. Fèvre, M. Kaare & P.G. Coleman. 2002. Estimating human rabies mortality in the United Republic of Tanzania from dog bite injuries. Bulletin of the World Health Organization, 80: 304-310.


Objective: To make quantitative predictions about the magnitude of underreporting of human rabies deaths in the United Republic of Tanzania.
Methods: Human rabies deaths were estimated by using a series of probability steps to calculate the likelihood of rabies developing
after the bite of a suspected rabid dog, incorporating field data on the incidence of animal bite injuries, the accuracy of rabies
recognition, the distribution of bite wounds, and post-exposure treatment.
Findings: Predicted human rabies mortality was estimated to be (a) 1499 deaths per year (95% confidence interval 891–2238),
equivalent to an annual incidence of 4.9 (2.9–7.2) deaths/100 000, when active surveillance data on bite incidence were used, and
(b) 193 deaths per year (32–409), corresponding to an annual incidence of 0.62 (0.1–1.32) deaths/100 000, when national bite
statistics were used. The annual mean number of rabies deaths officially recorded for the same period was 10.8 (7.7–14.0).
Conclusion: In the United Republic of Tanzania, cases of rabies in humans have been greatly underreported. Dog bite injuries are an accessible source of epidemiological data that may be used to estimate the public health burden of rabies and to monitor epidemiological trends in developing countries.

Estimación de la mortalidad por rabia humana causada por mordeduras de perro en la República Unida de Tanzanıa.

Objetivo: Hacer predicciones cuantitativas sobre la magnitud de la subnotificación de las defunciones por rabia humana en la República Unida de Tanzania.
Métodos: Se estimó la mortalidad por rabia humana usando una serie de pasos probabilísticos para calcular el riesgo de desarrollar rabia tras la mordedura de un perro presuntamente rabioso; a ese fin, se incorporaron datos de campo sobre la incidencia de mordeduras, la precisión del diagnóstico de la rabia, la distribución de las mordeduras y el tratamiento posterior a la exposición.
Resultados: Según las predicciones efectuadas, usando los datos aportados por la vigilancia activa de las mordeduras la mortalidad ascendía a (a) 1499 defunciones al año (intervalo de confianza (IC) 95%: 891–2238), lo que equivale a una incidencia anual de 4,9 (2,9–7,2) defunciones/100 000; al emplear las estadísticas nacionales sobre mordeduras, en cambio, se obtenían 193 defunciones anuales (32–409), lo que se traduce en una incidencia anual de 0,62 (0,1–1,32) defunciones /100 000. La media anual oficial para el mismo periodo fue de 10,8 (7,7–14,0) muertes por rabia.
Conclusión: En la República Unida de Tanzania, la notificación de los casos de rabia humana ha estado muy por debajo de las cifras reales. La información sobre las lesiones por mordedura de perro es una fuente accesible de datos epidemiológicos que pueden utilizarse para estimar la carga de salud pública que supone la rabia y para vigilar las tendencias epidemiológicas en los países en desarrollo.