Bells reduce predation by cats in NZ

Gordon, J. K., Matthaei, C., & Van Heezik, Y. (2010). Belled collars reduce catch of domestic cats in New Zealand by half. Wildlife Research, 37(5), 372-378.

Context. As evidence accumulates implicating domestic cats as significant predators of urban wildlife, the need for effective mitigation of potentially negative impacts becomes more pressing. Belled collars are probably one of the cheapest and least intrusive methods, although the opinion of a proportion of members of the public in New Zealand is that they are not effective.

Aims. We aimed to determine whether belled collars reduced prey catch.

Methods. Prey caught and brought back home by cats that were regular hunters during 6 weeks when they wore a belled collar was compared with prey caught during 6 weeks when they did not wear a collar.

Key results. Predation of birds and rodents was reduced by 50% and 61%, respectively. The number of rats, lizards and insects was not significantly reduced; however, these constituted a small proportion of the total catch. Sex and age of cats, as well as time did not affect catch rates, with the exception that older cats were more likely to catch rats (Rattus spp.) than were younger cats. Most of the cats in the study were young, reflecting our selection criteria that cats be regular and frequent hunters.

Conclusions. The degree to which catch of birds and rodents was reduced is similar to that reported in two experimental studies in the UK, and confirms that belled collars are effective in the New Zealand environment.

Implications. In New Zealand, small mammals are introduced pests and hunters of native wildlife; predation by cats may regulate their populations in urban areas and so care should be taken when instituting cat-control measures. It is also possible that a 50% reduction in predation may be insufficient to ensure viability for some urban wildlife populations.

Read a short review about belling effectiveness

Life+ project on wolf-dog hybridisation in Italy

See more about wild canid hybridisation with dogs

Los gatos y la pérdida de arena amenazan Maspalomas

http://www.canariasahora.es/articulo/medio-ambiente/gatos-y-perdida-arena-amenazas-reserva-maspalomas/20130722160540409692.html

 La caza de crías de chorlitejo por los felinos se suma a la pérdida anual de 40.000 metros cúbicos de arena como peligro del ecosistema dunar.
La intensa actividad sexual que se desarrolla en la Reserva Natural de las Dunas de Maspalomas, que ha vuelto a poner de actualidad un reportaje sobre Gran Canaria emitido recientemente en televisión, no es de las cosas que más preocupa a los gestores de la reserva. “Eso es un problema de orden público, a mí me da lo mismo un señor que arranca una planta como que dos personas se encuentren en las Dunas para mantener relaciones, son usos que no están contemplados en la norma”, comenta Miguel Ángel Peña, biólogo y director conservador de la Reserva Natural Especial de las Dunas de Maspalomas. Desde el área de conservación de este peculiar ecosistema, único en todo el Archipiélago canario, denuncian la falta de agentes medioambientales en la Reserva que vigilen la actividad humana, que incide fuertemente en la pérdida de arena y en la fauna de la zona. “Nos hemos gastado 18.000 euros en renovar la señalización, fundamental para la ordenación del uso público de la Reserva, pero no es suficiente” sentencia Peña. Desde hace varias semanas, la Reserva cuenta con 63 nuevas señales integradas en la Red Natura 2000 con aluminio amonizado (preparado para el exterior), escritas en 3 idiomas y con códigos QR para los teléfonos inteligentes. Sin embargo, comenta con indignación Peña, "las personas que transitan la zona continúan haciendo uso indebido de los distintos espacios que integran la Reserva”. En uno de estos espacios, la Charca, zona de exclusión en la que no está permitido el tránsito, no es el hombre, precisamente, quién trae de cabeza a los técnicos de la Reserva, sino los gatos. “Yo mismo he visto a más de uno, procedente de los chalés colindantes, darse un festín junto a la orilla de la Charca de Maspalomas”, señala Peña. El instinto cinegético de estos animales, que se escapan de las casas cercanas por la negligencia de sus propietarios, es una de las principales preocupaciones de los operarios de la Reserva puesto que está incidiendo especialmente en la desaparición de las crías de los pocos ejemplares que quedan de dos especies protegidas que nidifican en la zona: el chorlitejo chico y el chorlitejo patinegro. Estas dos especies, que se unen al centenar de aves que pueblan la Reserva Natural entre residentes en la zona y especies migratorias, “crían en tierra, en los bordes de agua y en los bordes de sitios con mucha salinidad, por lo que es frecuente ver a los gatos dándose un banquete con los pollitos de estas especies, que ponen sus nidos cerca de la charca”, explica Peña. Además de esta devastadora estampa, es frecuente ver la orilla de la charca llena de peces muertos porque la gente que se acerca hasta allí, -aunque está prohibido- les echa comida y luego cuando sube la temperatura y falta el oxígeno, muere el sobrante de especies que no puede soportar el reducido ecosistema de la charca. También la mano humana ha hecho que aumente considerablemente el tamaño de los lagartos gigantes que proliferan en la Reserva Natural, puesto que además de la comida que les suministra la gente, comen todos los restos que encuentran en la zona, un asunto sobre el que Peña se pronuncia rotundamente: “las Dunas de Maspalomas no es un parque temático, es una Reserva Natural, hay que dejar que el ecosistema evolucione solo, ni soltar gatos, ni echar comida a las especies animales ni repoblarlo beneficia al sistema sino que lo altera y perjudica sustancialmente”. La Reserva Natural de Maspalomas tiene un Plan Director de ordenación que se aprobó en el año 1999 y que regula íntegramente los usos y actividades tanto desde el punto de vista ambiental como urbanístico. En dicho documento quedan establecidas las distintas zonas que existen dentro de la Reserva: zona de Anexo II, zona dunar o de arenas, el palmeral y la zona de la charca. A cada una de estas zonas se le da un uso específico. “Las Dunas están categorizadas como zona de uso restringido”, explica Miguel Ángel Peña, “las personas, por tanto, pueden pasar caminando para usos educativos o para ir a la playa por uno de los cinco senderos habilitados para ello. Cualquier persona que haga otro uso de esas infraestructuras está infringiendo la ley”. En Maspalomas se pierden 40.000 metros cúbicos de arena al año Para este biólogo la circulación de personas fuera de los senderos no es por capricho, sino que responde a la necesidad de afectar lo menos posible al movimiento de arena, a la fauna y a la vegetación que están allí. “Numerosos estudios científicos muy sesudos han dejado patente que en Maspalomas se pierden 40.000 metros cúbicos de arena al año”, sentencia Miguel Ángel Peña. Esta pérdida de arena se debe, según el conservador de la Reserva Natural de las Dunas de Maspalomas, a las corrientes marinas que arrastran arena hacia la Punta de Maspalomas, desde dónde cae a una fosa oceánica, a la actividad turística -que ha afectado a la geomorfología de la zona, a la vegetación y a la fauna-, y al tránsito de personas que afecta negativamente al movimiento dunar. “Es como una gota de agua que está cayendo de forma permanente desde hace 50 años” explica Miguel Ángel Peña. Estudios procedentes de expertos de la Universidad de Las Palmas de Gran Canaria, de la Universidad de Cantabria y de la Universidad de Valencia acreditan que tanto la destrucción de las plantas de balancones, que se sitúan paralelas a la línea de costa, (sólo queda un 30% de las que inicialmente había en las Dunas de Maspalomas), como el yacimiento submarino por el que se pierde la arena de la playa y la actividad humana intensifican la reducción de arena. Un proyecto piloto para detener la pérdida incesante Una de las soluciones para evitar esta continua pérdida es darle una segunda vida a la arena. “Antes de que se pierda por la Punta de Maspalomas, lo que se trata es de extraerla y reinyectarla a la Playa del Inglés”. Según Miguel Ángel Peña, hay un proyecto que explica cómo hacer esto a través de una experiencia piloto en la sede del Ministerio de Medio Ambiente, un proyecto que realizó la empresa Ingenia SGI -a instancias del Consorcio para la Rehabilitación Turística del Sur de Gran Canaria- con el nombre Intervención Piloto y Monotorización del Balance Sedimentario de las Dunas y Playas de Maspalomas y el Inglés. “Estamos a la espera de que se pronuncie el Ministerio”, responde Peña en cuanto a la viabilidad de este proyecto, “evidentemente es una experiencia piloto que tiene unos costes y luego hay que evaluar el impacto del mismo”. Para Peña la falta de arena en Maspalomas es un problema turístico, no medioambiental, con consecuencias directas en el empleo y en la economía. “Ni la arena ha estado siempre ahí ni va a estar” pero nos convendría poner en valor lo que tenemos porque no lo hacemos. En Canarias no hay ningún otro ecosistema como el de las Dunas de Maspalomas, con un sistema arenoso, una laguna costera y un palmeral, esto no se tiene en cuenta por el común de las personas que lo perciben como un solarium a dónde ir a tenderse para tomar el sol”. El palmeral, declarado BIC, y la celebración de bodas en las Dunas Otra de las cuestiones que han devuelto a la palestra las Dunas de Maspalomas, aparte del citado reportaje de televisión, es la reciente declaración del palmeral como Bien de Interés Cultural por ser un lugar dónde estuvo, en su tránsito hacia América, el ilustre marino Cristóbal Colón. “Cuando se concluya el expediente veremos si podemos tener acceso, espero que con unos recursos adecuados para ello”, señala Peña, quien sostiene que esta declaración del palmeral como Bien de Interés Cultural por parte del Cabildo de Gran Canaria va a suponer un bien colectivo para todos. “Una de las misiones que tiene la Reserva es aumentar el conocimiento específico y espero que podamos obtener la cooperación activa de los cargos administrativos y técnicos de Patrimonio para poder operar en esa parte del Palmeral”. Respecto a la celebración de bodas en las Dunas, el conservador de la Reserva lo tiene claro. “No veo ningún problema en que se celebren bodas en la playa, que es un área de sensibilidad ecológica pero no que está dentro del término de la Reserva”. En cualquier caso tendrían que estar perfectamente organizadas, con un número determinado de personas y llevarse a cabo en unas condiciones reguladas. Lo que está totalmente prohibido es que se celebren en cualquiera de las áreas protegidas como son las Dunas, la Charca o el Palmeral”.

Potential use of secondary poison to control feral cat on islands

Dowding, J. E., Murphy, E. C., & Veitch, C. R. (1999). Brodifacoum residues in target and non-target species following an aerial poisoning operation on Motuihe Island, Hauraki Gulf, New Zealand. New Zealand Journal of Ecology, 23(2), 207-214.

Aerial poisoning using Talon^® 7-20 baits (active ingredient 20 ppm brodifacoum) was carried out on Motuihe Island, Hauraki Gulf, during the winter of 1997. The operation aimed to eradicate Norway rats (Rattus norvegicus) and house mice (Mus musculus) and to reduce rabbit (Oryctolagus cuniculus) numbers significantly. We studied the diet of feral house cats (Felis catus) before the operation, then monitored the impact of the operation on them to determine whether secondary brodifacoum poisoning caused a reduction in their numbers. Large numbers of rabbits remained after poisoning; this and other observations suggested that insufficient bait had been applied to achieve the aims of the programme. Cat mortality, based on radio-collared animals, was 3/14 (21%). Cats on Motuihe Island appeared to eat rabbit muscle tissue in preference to internal organs; brodifacoum concentrations are lower in muscle than in liver and we suggest that rabbits may be a poorer vector than rodents for secondary poisoning of cats. We also confirmed the risk of an aerial brodifacoum application to a range of non-target bird species. Mortality of pukeko (Porphyrio p. melanotus) and paradise shelducks (Tadorna variegata) was 49% and 60% , respectively. No mortality of New Zealand dotterels (Charadrius obscurus) or variable oystercatchers (Haematopus unicolor) was detected. Twenty-nine individuals of 10 bird species (five indigenous and five introduced) were found dead after the operation and livers of all of them contained residues of brodifacoum; toxin levels averaged 0.84 µg g^-1 (range 0.12-2.31 µg g^-1).

Dog, the most recorded carnivore in Brazilian Atlantic forest

Paschoal, A. M. O., Massara, R. L., Santos, J. L., & Chiarello, A. G. (2012). Is the domestic dog becoming an abundant species in the Atlantic forest? A study case in southeastern Brazil. Mammalia, 76(1), 67-76.

The Brazilian Atlantic forest has been reduced to a small fraction of its original area, with most remaining fragments being small and surrounded by anthropogenic matrices. This degree of disturbance, together with the increasing sprawl of cities towards the rural zone, greatly facilitates the entrance of domestic animals into these remnants. We used camera traps to compare the abundances of the domestic dog with a similarly sized native carnivore, the ocelot, in a 957-ha reserve of the Brazilian Atlantic forest in a landscape largely composed by pastures and agriculture. The dog was the most recorded species among all 17 mammal species “captured” by the cameras. Dog abundance (32–38 dogs) and density (0.812–1.813 dogs/km²) were significantly higher than that of the ocelot (n=2 ocelots; density=0.158–0.347 ocelots/km²). Although our result is restricted to a single study site, it is supported by an increasing number of recent studies, which have detected dogs inside other Atlantic forest reserves. Our study suggests, therefore, that this invasion might be more widespread than generally thought. The presence of the domestic dog is a threat to native fauna and constitutes an important edge effect of human presence at the rural zone.

Dogs outcompete Indian foxes for human-derived food

Vanak, A. T., & Gompper, M. E. (2009). Dietary niche separation between sympatric free-ranging domestic dogs and Indian foxes in central India. Journal of Mammalogy, 90(5), 1058-1065.

The competitive dynamics between domestic and native carnivores are poorly studied. We examined competition for food between sympatric populations of free-ranging dogs (Canis familiaris) and Indian foxes (Vulpes bengalensis) through dietary analysis in a protected, dry grassland habitat in central India. We expected significant dietary overlap between dogs and foxes because of clear evidence of interference competition between dogs and foxes in this area. However, dogs subsisted largely on human-derived foods (HDFs) from direct feeding, and scavenging on garbage, crop residue, and livestock carcasses (83% relative occurrence [RO]). Wild-caught foods constituted only 11% RO of the diet of dogs. The majority of the diet of Indian foxes consisted of invertebrates (33% RO), rodents (20% RO), and fruits of Zizyphus (18.5% RO). Indian foxes did not consume HDF, nor did they scavenge from large-mammal carcasses, and included only a small portion of agricultural produce in their diet. The low contribution of HDF and agricultural food sources to the diet of Indian foxes was surprising because this species is a generalist omnivore. Dogs may be preventing foxes from accessing agricultural lands and human-associated foods by interference competition.

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Effect of free‐ranging dogs on a native mesocarnivore

Vanak, A. T., & Gompper, M. E. (2010). Interference competition at the landscape level: the effect of free‐ranging dogs on a native mesocarnivore. Journal of Applied Ecology, 47(6), 1225-1232.

1. Free-ranging domestic dogs are the world’s most common carnivore and can negatively interact with native wildlife at multiple levels. Yet the intraguild competitive effects of dogs on the distribution and habitat use of native carnivores are poorly known, especially in areas of conservation concern.

2. We examined the spatial distribution of sympatric populations of radiocollared Indian foxes and free-ranging dogs to determine if Indian foxes alter their habitat use in the presence of dogs. We tested the effects of landcover type, primary prey abundance (rodents) and the presence of dogs as predictors of Indian fox spatial distribution in a threatened grassland habitat in central India.

3. By counting rodent burrows, we determined that the relative abundance of rodents was higher in fallow land and agricultural land compared to natural grasslands. From radiotelemetry data, we determined that the presence of dogs was closely linked to human-modified habitats, such as agricultural land and human settlements.

4. Top ranked models, based on Akaike’s Information Criterion corrected for small sample size, indicated that the negative effects of the presence of dogs and agricultural land, and the positive effects of the presence of grassland and fallow land habitats were the strongest predictors of Indian fox spatial distribution. Thus, the use of the landscape by Indian foxes was determined not only by habitat type, but also by the presence of a mid-sized carnivore, the dog.

5. Synthesis and applications. Our results show that the presence of domestic dogs on the periphery of natural habitats can interfere with the spatial distribution of a sympatric carnivore. Vaccination and sterilization programmes, aimed at reducing population sizes and pathogen prevalence, do not restrict the free-ranging behaviour of dogs. Therefore, in areas of conservation value, control of free-ranging dogs would be required to fully mitigate the deleterious effects of dogs on native carnivores and other wildlife.
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Behavioural interactions between dogs and wild canids

Vanak, A. T., Thaker, M., & Gompper, M. E. (2009). Experimental examination of behavioural interactions between free-ranging wild and domestic canids.Behavioral Ecology and Sociobiology, 64(2), 279-287.

The structure of mammalian carnivore communities is strongly influenced by both intraguild competition and predation. However, intraguild interactions involving the world’s most common carnivore, the domestic dog (Canis familiaris), have rarely been investigated. We experimentally examined the behavioural responses of a small canid, the Indian fox (Vulpes bengalensis), to the presence of dogs and dog odours. Resource competition between dogs and Indian foxes is low, so it is unclear whether foxes perceive dogs as interference competitors. To test this, we exposed foxes to neutral, live dog, and animal odour stimuli at food trays, and recorded the time spent at food trays, the amount of food eaten, and vigilance and non-vigilance behaviours. When dogs were visible, foxes continued to visit the food trays, but reduced the amount of time spent and food eaten at those trays. Foxes were more vigilant during dog trials than during neutral and odour trials and also exhibited lower levels of non-vigilance behaviour (resting and playing). In contrast, dog odours did not affect fox foraging and activity. These results show that vigilance/foraging trade-offs due to interference competition can occur between native and domestic carnivores despite low dietary overlap. These negative effects of dogs on a smaller member of the carnivore guild raise conservation concerns, especially for endangered carnivores. In many parts of the world, free-ranging dog densities are high due to human subsidies, and these subsidized predators have the potential to exacerbate the indirect effects of human presence.

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Hybridisation of canids in Australia

Stephens, D. (2011). The molecular ecology of Australian wild dogs: hybridisation, gene flow and genetic structure at multiple geographic scales. PhD, The University of Western Australia, Perth.

Advances in molecular ecology, particularly over the past two decades, have allowed studies of populations to extend to increasingly broad geographic and temporal scales without sacrificing detail. Limitations on sample numbers and types are decreasing, as efficiency and techniques for extracting DNA from suboptimal sources (such as hair or scats) improve. In this thesis I use microsatellite DNA markers to produce the first study of population genetics in Australian wild dogs, including dingoes (Canis lupus dingo), feral domestic dogs (C. l. familiaris) and their hybrids. Dingoes are unique among the Australian vertebrate fauna because they were transported to the continent approximately 5,000 years ago.
They have therefore not been in the ecosystem on evolutionary timescales, but have been present much longer than other introduced species. Dingoes are Australia’s apex predator, and have spread across habitats from deserts to tropical forests, but are currently under threat of extinction due to widespread hybridisation with domestic dogs. The conservation of dingoes is a management priority in some areas, but in others they are actively persecuted to protect livestock from predation.
The research areas addressed in this thesis are: the type of genetic samples best suited to different questions in research on wild dogs; the locations of pure dingoes; the patterns of gene flow among individuals and groups; and the degree of variability in spatial ecology across their range. Research outcomes are also placed into the context of how they can inform the management of wild dogs. Comparison of three non-invasively collected DNA sources with each other and with an invasively collected source (DNA swabs) showed that non-invasive samples, particularly scats, can be an appropriate source of DNA for monitoring based on
identification of individual. The costs and time involved in quality control of noninvasive samples, however, make them a less attractive option for large-scale or population-level studies, which require more genetic markers. I therefore employed tissue samples sourced from culling programs to examine aspects of
gene flow at four geographic scales. At the continental scale, I assessed the level of interbreeding between dingoes and domestic dogs, using both established methodology and a Bayesian clustering approach. Both methods provided similar results, showing increased hybridisation in coastal areas, particularly the
southeast of Australia, but fewer hybrids in the inland areas with lower densities of human settlement. Because population structure may affect approaches to control of wild dogs and conservation of dingoes, I then examined the scale and pattern of genetic subdivision and relatedness in three regions: the Tanami desert in the northern central region of Australia; south Queensland on the east coast; and across the western third of the continent. Wild dogs showed unexpected patterns of population structure, with variations in the geographical extent and separation of clusters. Relationships and spatial ecology of wild dogs in the Tanami desert appeared to be strongly affected by human activity, particularly the presence of artificially abundant food resources. The wild dogs sampled in south Queensland and Western Australia showed distinct genetic clusters in the absence of geographic barriers, showing that Australian wild dogs display cryptic genetic
subdivision at a similar scale found in wolves in vastly different habitats. The findings of this study reinforce the variability found in Australian wild dogs previously demonstrated by studies of diet and movements, and provide a novel and comprehensive overview of gene flow both among wild dogs and between dingoes and domestic dogs.

See more about wild canid hybridisation with dogs

Free ranging domestic cats' demography

Warner, R. E. (1985). Demography and movements of free-ranging domestic cats in rural Illinois. The Journal of wildlife management, 49(2): 340-346.

Free-ranging domestic cats on farmsteads were censused annually in August 1977-81 within a 5,182-ha area typical of the cash-grain region in central Illinois. The estimated average number of cats on the area in late summer was 326 (6.3/100 ha). Annual recruitment of immature cats into the late summer population averaged 1.5/adult female. Survival beyond 3-5 years of age was rare; <1% survived 7 or more years. Eleven adult cats were radio-monitored during a 30-day period in summer; four males ranged over larger areas (P < 0.01) than seven females (228 ± 100 ha and 112 ± 21 ha, respectively). When cats were not on farmsteads, approximately 73% of their radiolocation points (N = 1,227) were in edge or linear configurations of cover. Cats made disproportionately high (P < 0.05) use of farmsteads and perimeters, roadsides, and field interfaces and disproportionately low use (P < 0.05) of fields of corn and soybeans. Domestic cats on the area were well fed by humans but routinely deposited prey at their residences.

Cat predation on rural and urban landscapes

Lepczyk, C.A., Mertig, A.G. & Liu, J. (2003) Landowners and cat predation across rural-to-urban landscapes. Biological Conservation 115: 191–201

Fluctuations of bird abundances have been attributed to such factors as supplemental feeding, landscape change, and habitat fragmentation. Notably absent from consideration, however, is the role of private landowners and their actions, such as owning free-ranging domestic cats (Felis catus; cats allowed free access to the outdoors). To understand the impacts of cat predation on birds, we surveyed all 1694 private landowners living on three breeding bird survey (BBS) routes (∼120 km) that represent a continuum of rural-to-urban landscapes in Southeastern Michigan, where the majority (>90%) of land is privately owned. Our data indicate that among the 58.5% of landowners that responded, one quarter of them owned outdoor cats. On average a cat depredated between 0.7 and 1.4 birds per week. A total of 23+ species (12.5% of breeding species) were on the list of being killed, including two species of conservation concern (Eastern Bluebirds and Ruby-throated Hummingbirds). Across the three landscapes there were ∼800 to ∼3100 cats, which kill between ∼16,000 and ∼47,000 birds during the breeding season, resulting in a minimum of ∼1 bird killed/km/day. While the number and density (no./ha) of free-ranging cats per landowner differed across the rural to urban landscapes, depredation rates were similar. Landowner participation in bird feeding showed no relationship with the number of free-ranging cats owned. Similarly, selected demographic characteristics of landowners were not significantly related to the number of free-ranging cats owned. Our results, even taken conservatively, indicate that cat predation most likely plays an important role in fluctuations of bird populations and should receive more attention in wildlife conservation and landscape studies.

Interspecific variation in susceptibility to cat predation

Møller, A. P., Erritzøe, J., & Nielsen, J. T. (2010). Causes of interspecific variation in susceptibility to cat predation on birds. Chinese Birds, 1(2), 97-111.

Generalist mammalian predators hunt for prey in different ways than raptors, often relying on ambush attack. Such differences in predator behavior can have profound effects on susceptibility of different species of prey to predation, but can also modify the behavior of prey. We investigated susceptibility of common birds to predation by domestic cats Felis catus, relying on an extensive data set on prey abundance and prey availability as determined by standardized bird counts. Susceptibility to cat predation for different species of birds was not significantly correlated with susceptibility to predation by sparrowhawk Accipiter nisus, but with susceptibility to goshawk Accipiter gentilis predation. Susceptibility to goshawk predation was independently predicted by susceptibility to cat and sparrowhawk predation. We cross-validated our estimate of susceptibility to cat predation by showing that the frequency of birds with tail loss increased strongly with susceptibility to cat predation. Male birds were disproportionately preyed upon, especially if having song posts low in the vegetation, and if having short flight distances when singing. Colonially breeding species were less susceptible to predation than solitary species. Bird species with high levels of innate immune defense against bacterial infections had high susceptibility to cat predation. These findings suggest that predation by cats has been an important selection pressure affecting anti-predation behavior, sexual display and immune function in common birds.

Birds' choice of song posts

Møller, A. P. (2011). Song post height in relation to predator diversity and urbanization. Ethology, 117(6), 529-538.

Birds may sing from positions in the vegetation (song posts) to allow efficient transmission of sexual and territorial vocal displays while simultaneously minimizing the risk of predation because of avian and mammalian predators. Because urban areas are deficient in specialized avian predators, but have many cats while the opposite is the case for nearby rural areas, urban birds should display higher in the vegetation. In a comparison of the abundance of predators in three cities (Oslo, Brønderslev, Orsay), I show that avian predators are more common in rural areas, while mammalian predators are more common in urban areas. Singing birds sang from higher positions in the vegetation of urban than nearby rural areas. Differences in song post heights between urban and rural areas were consistent among cities, suggesting inherent specific difference in microhabitat choice. Bird species that have become urbanized recently had similar song post heights in urban and rural habitats, while species that have been urbanized for a long time sang from relatively higher song posts in urban areas. These findings suggest that urban and rural birds differ in habitat use when singing. These differences in song post choice between urban and rural habitats may have a number of consequences for vocal displays in the two different habitats.

Escape behaviour related to different predators in urban or rural habitats

Møller, A. P., & Ibáñez-Álamo, J. D. (2012). Escape behaviour of birds provides evidence of predation being involved in urbanization. Animal Behaviour, 84 (2): 341–348

Altered predation risk in urban environments may contribute to animals becoming successfully urbanized by individuals from rural habitats. Escape behaviour has evolved to allow an individual to escape once captured by a predator. We tested whether altered predation risk in urban environments is associated with colonization of such habitats by comparing escape behaviour of 1132 individual birds belonging to 15 species from nearby rural and urban populations when captured by a human. Raptors (of which the Eurasian sparrowhawk, Accipiter nisus, was one of the most common species) were more common in rural than in urban habitats, whereas cats, Felis catus, showed the opposite pattern. There were consistent differences in escape behaviour between habitats, showing divergence in behaviour from the ancestral rural state. Urban birds wriggled less, showed higher tonic immobility, more often lost feathers, were less aggressive by biting less often, and emitted fear screams and alarm calls more often than rural birds. Furthermore, differences in escape behaviour between habitats were related to susceptibility to predation by sparrowhawks, as expected if differences in behaviour were due to differences in predation risk. Finally, an analysis of differences in escape behaviour between rural and urban birds revealed a significant relationship with time since urbanization, suggesting that escape behaviour has changed in urban environments over time. These findings suggest that release from predation and change in predator community associated with urbanization has altered the antipredator behaviour of birds colonizing towns and cities.

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Highlights

► We investigated escape behaviour of urban and rural birds. ► Urban birds tried to escape less actively and gave more alarm calls than rural birds. ► These differences were related to susceptibility to predation by sparrowhawks. ► The degree of divergence was related to time since urbanization. ► Predation is an important selection force driving adaptation to urban habitats.

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.

Identifying seabirds' predators with DNA and cams

Steffens, K. E., Sanders, M. D., Gleeson, D. M., Pullen, K. M., & Stowe, C. J. (2012). Identification of predators at black-fronted tern Chlidonias albostriatus nests, using mtDNA analysis and digital video recorders. New Zealand Journal of Ecology, 36(1), 48. 

Predators at black-fronted tern (Chlidonias albostriatus) nests on the Wairau braided riverbed in Marlborough, New Zealand, were identified using (1) mtDNA analysis of 438 swabs from shell remains, nest contents, and carcass remains, and (2) digital video surveillance of 85 nests. DNA analysis suggested harriers (Circus approximans) were the main predator of tern eggs (171 of 192 shell samples containing predator DNA). Cats (Felis catus) and stoats (Mustela erminea) were the probable predators of the majority of adult terns killed (9 and 8 respectively, of swabs from 19 carcasses). Video results were broadly, though not entirely, consistent with the DNA results, and showed that harriers were the main predator of eggs (9 of 19 videoed predation events), followed by Southern black-backed gulls (Larus dominicanus dominicanus; 3/19); hedgehogs (Erinaceus europaeus occidentalis; 2/19), ship rats (Rattus rattus; 2/19), pied oystercatchers (Haematopus finschi; 2/19) and stoats (1/19). DNA was analysed from nine of the 19 videoed nests but the only predator DNA obtained was from harriers (four nests). Sixty-four percent of depredated nests (683/1063) contained no eggshell remains at the next monitoring visit after predation. DNA analysis of nest material from 71 of these empty nests yielded only one predator result; video footage was therefore essential to identify the cause of 12 empty nests at 19 videoed nest predations. Terns removed the depredated egg remains from eight nests; blackbacked gulls consumed eggs at three nests; and a stoat carried the eggs away from one nest. Hedgehog DNA was not found on shell remains from nests with videoed hedgehog predations. Analysing DNA from eggshell and carcass remains is a valuable new tool in wildlife research and management because it can identify predator species and indicate their relative importance. However, our results show that predator species are not equally detectable using this technique, leading to biases in the DNA results. This ‘detectability bias’ needs to be further quantified, and recognised when interpreting DNA results.

DNA to prove cat predation on native carnivores

Glen, A. S., Berry, O., Sutherland, D. R., Garretson, S., Robinson, T., & De Tores, P. J. (2010). Forensic DNA confirms intraguild killing of a chuditch (Dasyurus geoffroii) by a feral cat (Felis catus). Conservation Genetics, 11(3), 1099-1101.

Because animals killed by predators are often found partially consumed or decomposed, identification of the predator is often unachievable by post mortem examination. Forensic DNA offers an alternative in such situations. Using a novel method to analyse DNA from bite wounds on a freshly-killed chuditch Dasyurus geoffroii, we describe the first confirmed instance in this species of intraguild killing by a feral cat. Unlike post mortem examination, our method of DNA melt curve analysis is highly accurate and requires less time and expense than DNA sequencing.

Antiquity of dog introduction on California's Channel Islands

Rick, T. C., Walker, P. L., Willis, L. M., Noah, A. C., Erlandson, J. M., Vellanoweth, R. L., Braje, T.J. & Kennett, D. J. (2008). Dogs, humans and island ecosystems: the distribution, antiquity and ecology of domestic dogs (Canis familiaris) on California's Channel Islands, USA. The Holocene, 18(7), 1077-1087.

Archaeologists have made significant contributions to our understanding of ancient island environments, including the timing and implications of the introduction of non-native animals (pigs, chickens, rats, etc.) by humans.
Here, we focus on the historical ecology and biogeography of domestic dogs (Canis familiaris) on California's Channel Islands during the Holocene. Dogs are the only animal known unequivocally to have been introduced by Native Americans to the islands, but relatively little is known about their distribution, antiquity or influence on native island fauna and flora. We identified a minimum of 96 dogs from 42 archaeological sites on six of the eight islands. Dogs were present for at least 6000 years and appear to have increased in abundance through time. Our analysis suggests that dogs, along with humans and island foxes (Urocyon littoralis), would have had an impact on native animals and ecosystems, especially breeding birds and marine mammals. Dogs and island foxes likely competed with one another for food, however, and the impacts of dogs on island ecosystems may have been reduced by the presence of island foxes and the symbiotic relationship between dogs and humans. Dogs have been removed from all but one of the islands today, eliminating one of the few terrestrial carnivores present for most of the Holocene.

Dog as a disturbance agent

Holderness-Roddam, B (2011) The effects of domestic dogs (Canis familiaris) as a disturbance agent on the natural environment. Research Master thesis, University of Tasmania.

This study assesses the impact of domestic dogs on the natural environment. The principal issue investigated is that of disturbance and the consequences for native wildlife, particularly vertebrate species. In addition to the catastrophic effects of killing, maiming and orphaning of wildlife; disturbance can contribute to energetic loss through premature flight or reduced feed intake and reproductive disruption due to nest disturbance. Dogs have been implicated in disease transmission to native wildlife; with faecal contamination of waterways having potential negative affects for marine mammal health. Hybridisation with other canid species is also an issue of concern, as is expropriation of land for the production of food for pet dogs.

The study commences with an overview of ecological disturbance. The literature review then assesses the role of domestic dogs in ecological disturbance, public attitudes towards compliance with dog management legislation and the remediation and mitigation of disturbance by dogs. 

Data obtained from the Resource Management and Conservation section of the Tasmanian Department of Department of Primary Industries, Parks, Water and Environment regarding native wildlife presenting for care was analysed in order to determine the principal reported causes of death and injury to native wildlife in Tasmania. These results were then compared with data from the Australian Wildlife Health Centre - Wildlife Hospital at Healesville Sanctuary in Victoria and the data submitted by Tasmanian veterinarians through a three month diary of wildlife presentations recorded by ten practices.
The data is indicative of domestic dogs having a more deleterious effect than domestic cats on native wildlife in Tasmania; particularly in urban and suburban areas and on beaches.

Impact of dogs on gazelle kids

Manor, R., & Saltz, D. (2004). The impact of free-roaming dogs on gazelle kid/female ratio in a fragmented area. Biological Conservation, 119(2), 231-236.

One of the consequences of fragmentation is a combination of increased proximity to human dominated areas and an influx of free-roaming dogs. In fragmented habitats those dogs are expected to have a considerable impact on ungulate populations since conditions are, in effect, similar to alien species on islands.

 We studied the impact of free-roaming dogs (Canis familiaris) on the kid/mother ratio of mountain gazelle (Gazella gazella gazella) in an isolated area heavily disturbed by human activity. We used the kid/female ratio as an index of recruitment in the gazelle populations and evaluated the impacts of dog presence, intensity of human disturbance, and forage and cover availability on this ratio over space and time. Data were collected from direct observations. Overall, kid/female ratio in the area is too low for population growth; a finding that is in agreement with drive counts indicating a consistent decline over the past four years (1998–2001). Our results show that free-roaming dogs were the overwhelming factor affecting kid/female ratio in this area. Gazelles responded positively and quickly to dog culling. Thus, free-roaming dogs appear to be a considerable threat to the gazelle population in the study area. Removal of those dogs on a regular basis is an adequate short-term management protocol for increasing gazelle recruitment rate. However, a permanent solution would require reducing the number of dogs by limiting human waste disposal. These results suggest that, in addition to the loss of habitat and connectivity, free-roaming dogs can be a major threat to native ungulates in human dominated fragmented landscapes.

Effect of guard dogs on gazelles

Gingold, G., Yom‐Tov, Y., Kronfeld‐Schor, N., & Geffen, E. (2009). Effect of guard dogs on the behavior and reproduction of gazelles in cattle enclosures on the Golan Heights. Animal Conservation, 12(2), 155-162.

Cattle on the Golan Heights are kept in enclosures and some of these enclosures have guard dogs. We studied the effect of such dogs on the behavior and breeding success of mountain gazelles Gazella gazella living within enclosures. We found that guard dogs have both direct and indirect effects on gazelles. Gazelles living in enclosures with dogs spent more time in vigilance behavior and running, and less time resting and walking, in comparison with gazelles in dog-free enclosures. In the absence of dogs, gazelle female herds in enclosures tended to stay closer to the cattle, but shunned away from them in the presence of the dogs, which, in turn, remained near the cattle. The percentage of fawns per female was higher in enclosures without dogs in comparison with those with dogs, but the difference was not significant. However, the largest of the enclosures with dogs, which had the largest number of gazelles, had only an average number of dogs in it. Hence, the gazelles in this enclosure were better able to avoid the dogs in comparison with those in smaller enclosures. Removing this enclosure from the overall calculation revealed that guard dogs have a significant negative effect on gazelle reproductive success. In two of the four enclosures with dogs no fawn still survived 6 months after birth, while in each of the four enclosures without dogs some fawns did survive to that age and beyond, suggesting that the dogs themselves may predate the fawns.

Domestic dogs and edge effect

Lacerda, A. C. R., Tomas, W. M., & Marinho‐Filho, J. (2009). Domestic dogs as an edge effect in the Brasília National Park, Brazil: interactions with native mammals. Animal Conservation, 12(5), 477-487.

Edge effects are a well-known result of habitat fragmentation. However, little has been published on fragmentation, isolation and the intrusive influence from the surrounding matrix at the landscape level. The objectives of the present study are to evaluate the presence of dogs in the Brasília National Park (BNP) in relation to habitat type and the influence from the surrounding matrix. In addition, this study examines the response of the native mammal fauna to the presence of dogs. Track stations were built along dirt roads in the BNP and subsequently examined for the presence or absence of tracks. We used a stepwise logistic regression to model the occurrence of five mammal species relative to habitat variables, with an α=0.05 to determine whether to enter and retain a variable in the model. A simulation of each species occurrence probability was conducted using a combination of selected habitat variables in a resource selection probability function. Results indicate a negative relationship between distance from the BNP edge and the probability of dog occurrences. From an ecological perspective, the presence of dogs inside the BNP indicates an edge effect. The occurrence of the maned wolf was positively associated with distance from a garbage dump site and negatively associated with the presence of dog tracks. The maned wolf and giant anteater seem to avoid areas near the garbage dump as well as areas with dog tracks. There is no support for the possible existence of a feral dog population inside the BNP, but the effects of free-ranging dogs on the wildlife population in such an isolated protected area must not be neglected. Domestic dog Canis familiaris populations and disease control programs should be established in the urban, sub-urban and rural areas surrounding the BNP, along with the complete removal of the garbage dump from the BNP surroundings.

Diet of feral cats and dogs in suburban Brazil

Campos, C. B., Esteves, C. F., Ferraz, K. M. P. M. B., Crawshaw, P. G., & Verdade, L. M. (2007). Diet of free‐ranging cats and dogs in a suburban and rural environment, south‐eastern Brazil. Journal of Zoology, 273(1), 14-20.

In spite of the worldwide occurrence of domestic cats and dogs, and their close relationship with humans, the number of published papers on free-ranging cats Felis catus and dogs Canis familiaris, is small. The diet of both species was estimated in a suburban and rural environment in July 2002 and January 2003. Visual observations and scat collection of both species were accomplished along a 10 km transect line in the Campus ‘Luiz de Queiroz’, University of São Paulo, Piracicaba, south-eastern Brazil. The diet of both species was determined by analysis of sterilized, washed, dried and sorted scats. Estimated abundances of free-ranging cats and dogs in the sampled area were 81 (±4.32) and 42 (±2.96), respectively. Cats and dogs were more abundant in the suburban than in the rural environment (t=3.78, P<0.001, N=55; t=8.38, P<0.001, N=55, respectively) and cats were more abundant than dogs in the suburban environment (t=6.76, P<0.001, N=55), even though there was no significant difference between the abundance of both species in the rural environment (t=0.82, P=0.46, N=55). Invertebrates were the most commonly consumed item by both species, followed by mammals (cats: 63.24 and 20.51%; dogs: 57.05 and 25.15%, respectively). Niche breadth was 0.4892 for cats and 0.4463 for dogs. Niche overlap was almost complete (0.97108). The consumption of mammals was estimated to be between 16.76 and 25.42 kg individual−1year−1 for dogs and between 2.01 and 2.9 kg individual−1year−1 for cats. These data might be useful to establish a management program to minimize the predation pressure of free-ranging cats and dogs on wildlife.

Dogs in rural Zimbabwe: disease transmission and competition with scavengers

Butler, J. R. A., & Toit, J. T. (2002). Diet of free‐ranging domestic dogs (Canis familiaris) in rural Zimbabwe: implications for wild scavengers on the periphery of wildlife reserves. Animal Conservation, 5(1), 29-37.

Numbers of free-ranging dogs (Canis familiaris) have reached unprecedented levels in Zimbabwean communal lands (agropastoralist rural areas). This study examined the potential competitive interactions between dogs and wild scavengers on the boundary of Gokwe Communal Land (GCL) and the Sengwa Wildlife Research Area (SWRA) in 1995–96. Dietary studies showed that dogs were primarily scavengers of human waste and animal carcasses. Twelve experimental carcasses indicated that dogs were the most successful species in the vertebrate scavenger guild, consuming 60% of available biomass and finding 66.7% of carcasses. Dogs monopolized the supply of domestic animal carrion within GCL, but also consumed wild carrion up to 1 km within the SWRA, and were seen 3 km inside the reserve. Their principal competitors for carcasses were vultures, and to a lesser degree lions (Panthera leo), leopards (P. pardus) and spotted hyaenas (Crocuta crocuta). Dogs outcompete vultures on wildlife reserve boundaries owing to their high densities, nocturnal and diurnal activity, physical dominance and greater tolerance of human disturbance. With a population growth rate of 6.5% per annum the influence of dogs will intensify on the peripheries of reserves, exacerbating their existing threat to wild scavengers. This scenario is probably occurring in many other African countries.

Butler, J. R. A., Du Toit, J. T., & Bingham, J. (2004). Free-ranging domestic dogs (Canis familiaris) as predators and prey in rural Zimbabwe: threats of competition and disease to large wild carnivores. Biological Conservation, 115(3), 369-378.

Domestic dogs (Canis familiaris) arrived in Zimbabwe ca. 1000 years ago. Numbers of free-ranging dogs have reached unprecedented levels in communal lands (agro-pastoralist rural areas), and interact with large wild carnivores along boundaries with wildlife reserves as predators and prey. This study examined a population of 236 dogs in a 33-km² section of Gokwe Communal Land (GCL) bordering the Sengwa Wildlife Research Area (SWRA) in north-western Zimbabwe in 1995–1996. Dogs were found up to 6 km within the SWRA, and were the most common carnivore on the GCL–SWRA boundary. Observations of 16 radio-collared dogs showed that they were inefficient predators. Only 20 kills were recorded amongst the remaining dog population, of which three were wild ungulates. Dogs were unsuccessful predators due to their small group size (mean 1.7) and body mass (mean 14.7 kg), and the abundance of alternative food. It is therefore unlikely that they compete with large carnivores for wild prey. However, leopards (Panthera pardus), lions (P. leo) and spotted hyaenas (Crocuta crocuta) preyed on dogs in GCL, removing ⩾6% of the dog population in 1993. Such predation provides ideal circumstances for disease transmission. Canid disease was prevalent in the study area; including rabies and probably distemper. The risk of infection is greatest during the dry season (May–October), when peaks in rates of disease, carnivore incursions into GCL, and predation on dogs coincided. The role of jackals (Canis adustus and Canis mesomelas) and spotted hyaena predation of dogs is discussed in relation to disease epidemics within wildlife reserves. With a dog population growth rate of 6.5% per annum, and the prevalence of canid diseases, the conservation threat posed by dogs is escalating on communal land–wildlife reserve boundaries in Zimbabwe. Measures to control dog numbers and improve vaccination coverage of dogs are discussed.

Conservation in Florida Keys campaign

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PVA supports cats' control to manage endangered mammal

Forys, E. A., & Humphrey, S. R. (1999). Use of population viability analysis to evaluate management options for the endangered Lower Keys marsh rabbit. The Journal of wildlife management, 251-260.

We conducted a population viability analysis (PVA) for the federally endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri). We estimated parameters via livetrapping, radiotelemetry, and fecal-pellet counting during a 2.5-year study. Historically, this subspecies ranged throughout the Lower Keys of Florida, but today the marsh rabbit is limited to 41 subpopulations occurring in 3 distinct metapopulations. To evaluate this subspecies' risk of extinction, we used VORTEX, a simulation modeling program, that combined deterministic and stochastic birth and death events, differing migration rates based on spatially explicit patch structure, and extinction and recolonization. Our simulation calculated the chance that each metapopulation would go extinct under current conditions and several management scenarios. Under current conditions, the model predicted there is a 100% chance that all metapopulations will go extinct. The metapopulation with many small patches went extinct faster than the metapopulations with fewer, larger patches. The most effective strategy to decrease the risk of extinction of all 3 metapopulations was to increase the survival rate in several age and sex classes by eliminating predation by domestic cats.

Cat killed critically endangered orange-bellied parrots

From http://www.themercury.com.au
June, 27, 2013
Tasmania

TWO of the estimated 320 remaining orange-bellied parrots (Neophema chrysogaster) have died after a cat made its way into a government breeding enclosure.

The endangered birds, described by the Tasmanian Parks and Wildlife Service as one of the world's most rare and endangered bird species, died at Taroona last month.
Environment Minister Brian Wightman confirmed the deaths in Tasmanian Parliament yesterday.

"With a population of perhaps fewer than 50 individuals [in the wild], the species is critically endangered," he said."That is why it is very important we have correct housing for these birds."We will continue to ensure that the facilities we have in the north and south of the state are secure and my expectation as minister would be that if there has been an issue that it is fixed in a timely manner and we will undertake to make sure it has occurred."

Tasmanian Greens environment spokeswoman Cassy O'Connor said nothing should be left to chance with so few of the birds left in the wild."The orange-bellied parrot is perched at the brink of extinction, and this breeding program is critical to the survival of this treasured species," Ms O'Connor said."There is some incredible work being done to ensure the survival of the orange-bellied parrot in Tasmania, and the Greens commend everybody involved in the program."If we are going to put the effort and resources into a breeding program, then it's important to ensure that the security and staffing are adequate."

An inspection of an enclosure at Taroona, one of three major breeding facilities in Australia, showed a hole in the enclosure.A letter from Sandy Bay vet James Harris to Mr Wightman in late May said he suspected the intrusion by the cat had startled the birds.

A cat was trapped in the enclosure two days after the birds' deaths.

Two classics in ecology: Mesopredator release

Soulé, M. E., Bolger, D. T., Alberts, A. C., Wrights, J., Sorice, M., & Hill, S. (1988). Reconstructed dynamics of rapid extinctions of chaparral‐requiring birds in urban habitat islands. Conservation Biology, 2(1), 75-92.

The distribution of native, chaparral-requiring bird species was determined for 37 isolated fragments of canyon habitat ranging in size from 0.4 to 104 hectares in coastal, urban San Diego County, California. The area of chaparral habitat and canyon age (time since isolation of the habitat fragment) explains most of the variation in the number of chaparral-requiring bird species. In addition, the distribution of native predators may influence species number. There is statistical evidence that coyotes control the populations of smaller predators such as foxes and domestic cats. The absence of coyotes may lead to higher levels of predation by a process of mesopredator release. The distance of canyons from other patches of chaparral habitat does not add significantly to the explained variance in chaparral-requiring species number–probably because of the virtual inability of most chaparral-requiring species to disperse through developed areas and nonscrub habitats. These results and other lines of evidence suggest that chaparral-requiring birds in isolated canyons have very high rates of extinction, in part because of their low vagility. The best predictors of vulnerability of the individual species are their abundances (densities) in undisturbed habitat and their body sizes; together these two variables account for 95 percent of the variation in canyon occupancy. A hypothesis is proposed to account for the similarity between the steep slopes of species-area curves for chaparral-requiring birds and the slopes for some forest birds on small islands or in habitat fragments. The provision of corridors appears to be the most effective design and planning feature for preventing the elimination of chaparral-requiring species in a fragmented landscape.

En el condado urbano de San Diego, California 37 fragmentos de hábitat de cañón que varían de tamaño de 0.4 a 104 hectáreas fueron examinados para determinar la distribución de especies de aves nativas que requieren de chaparral. El tamaño del área de hábitat de chaparral y la edad del cañón (tiempo transcurrido desde que ocurrió el aislamiento del fragmento de hábitat explican la mayor parte de la variación en el número de especies de aves que requieren de este hábitat Así mismo, la distribución de depredadores nativos puede influenciar el número de especies. Existen evidencias estadísticas de que los coyotes controlan las poblaciones de depredadores menores tales como los zorros y los gatos domésticos. La ausencia de coyotes puede conducir a niveles de depredación mas altos mediante un proceso de liberación de mesodepredadores. El aislamiento de cañones con respecto a otros pedazos de hábitat de chaparral no incrementa significativamente la varianza en el número de especies que requieren chaparral – probablemente debido a la virtual inhabilitad de la mayoría de las especies que requieren chaparral para dispersarse en áreas desarrolladas y en hábitats no—arbustivos. Estos resultados y otras evidencias sugieren que las aves que requieren chaparral en los cañones aislados tienen muy altas tasas de extinción, en parte debido a su baja dispersabilidad. Los mejores pronosticadores de la vulnerabilidad de una especie en particular son su abundancia (densidad) en habitats no perturbados y el tamaño de sus cuerpos; juntas, estas dos variables explican el 95% de la variación de su residencia en el cañón. Una hipótesis es propuesta para explicar la similaridad entre las fuertes pendientes de la curves de especies-área para las aves que requieren chaparral y las pendientes para algunas aves de bosque en pequeñas islas o en hábitats fragmentados. La provisión de corredores parece ser el diseño y el rasgo de la planificación más efectivo para prevenir la eliminación de especies que requieren chaparral en un paisaje fragmentado.

Crooks, K. R., & Soulé, M. E. (1999). Mesopredator release and avifaunal extinctions in a fragmented system. Nature, 400(6744), 563-566.

Mammalian carnivores are particularly vulnerable to extinction in fragmented landscapes, and their disappearance may lead to increased numbers of smaller carnivores that are principle predators of birds and other small vertebrates. Such 'mesopredator release' has been implicated in the decline and extinction of prey species. Because experimental manipulation of carnivores is logistically, financially and ethically problematic, however, few studies have evaluated how trophic cascades generated by the decline of dominant predators combine with other fragmentation effects to influence species diversity in terrestrial systems. Although the mesopredator release hypothesis has received only limited critical evaluation and remains controversial, it has become the basis for conservation programmes justifying the protection of carnivores. Here we describe a study that exploits spatial and temporal variation in the distribution and abundance of an apex predator, the coyote, in a landscape fragmented by development. It appears that the decline and disappearance of the coyote, in conjunction with the effects of habitat fragmentation, affect the distribution and abundance of smaller carnivores and the persistence of their avian prey.

Dog attacks to livestock in Spain

Echegaray, J. & Vilà, C. (2010). Noninvasive monitoring of wolves at the edge of their distribution and the cost of their conservation. Animal Conservation, 13(2), 157-161.

Large predators are recolonizing areas in industrialized countries, where they have been absent for decades or centuries. As they reach these areas, the predators often encounter unwary livestock and unprepared keepers, which translates into large economic costs. The cost per individual may have important repercussions on the conservation and management of large predators. During the years 2003–2004, we collected 136 feces preliminarily identified as belonging to gray wolves Canis lupus along the north-eastern limit of the wolf range in the Iberia peninsula (Basque Country, Spain). Genetic analyses allowed us to identify the species of origin in 86 cases: 31 corresponded to wolves, two to red foxes Vulpes vulpes and 53 to dogs Canis familiaris. Among the wolves, we identified 16 different individuals. We estimated the cost of conserving wolves to be >€3000 per wolf per year, based on the cost of damage compensation and prevention during the 2003–2004 period. However, most of the wolf feces contained wild prey whereas dog feces contained mostly remains of domestic animals. This finding suggests that uncontrolled dogs could be responsible for some of the attacks on livestock, contributing to negative public attitudes toward wolf conservation and increasing its cost.

Feral dogs attack ... vultures!!

In 2009, a photographer witnessed the attack of apack of feral dogs to vultures in Segovia province, central Spain. They were probably attracted by the same carrion that the vulture had eaten, and this was probably too sated and cannot fly and escape the feral dogs. 

The photographer, Juan Pablo Fuentes Serrano, was able to save the bird and take it to a wildlife recovery center.

Forensics to identify livestock predators

Caniglia, R., Fabbri, E., Mastrogiuseppe, L., & Randi, E. (2012). Who is who? Identification of livestock predators using forensic genetic approaches. Forensic Science International: Genetics, 7(3): 397-404.

Molecular identifications of salivary DNA are increasingly applied in wildlife forensic investigations, and are successfully used to identify unknown livestock predators, or elucidate cases of large carnivore attacks to humans. In Europe most of livestock predations are attributed to wolves (Canis lupus), thought free-ranging dogs are sometime the responsible, and false predations are declared by breeders to obtain compensations.
 In this study we analyzed 33 salivary DNA samples collected from the carcasses of 13 sheep and a horse presumably predated by wolves in seven farms in central Italy. Reliable individual genotypes were determined in 18 samples (corresponding to samples from nine sheep and the horse) using 12 unlinked autosomal microsatellites, mtDNA control-region sequences, a male-specific ZFX/ZFY restriction-site and four Y-linked microsatellites. Results indicate that eight animals were killed by five wolves (a male and four different females), the ninth by a female dog while the horse was post-mortem consumed by a male dog. The genotype of one female wolf matched with the genetic profile of a female wolf that was non-invasively sampled 4 years before in the same area near livestock predation remains. Genetic identifications always supported the results of veterinary reports. These findings show that salivary DNA genotyping, together with detailed veterinary field and necropsy reports, provides evidence which helps to correctly identify species, gender and individual genetic profiles of livestock predators, thus contributing to clarify attack dynamics and to evaluate the impact of wolf predations on husbandry.