Dogs are a significant problem for the native mammal community in one Andean region

Zapata-Ríos, G., & Branch, L. C. (2016). Altered activity patterns and reduced abundance of native mammals in sites with feral dogs in the high Andes. Biological Conservation, 193, 9-16.

Negative impacts of some introduced carnivores like feral cats are well documented, widespread, and significant. Comparatively, the effects of feral dogs (individuals that are not associated with people or human settlements) on native wildlife are poorly known, even though feral dogs occur worldwide. We assessed the density of feral dogs and compared relative abundance, activity patterns and habitat use of 10 species of mammals in areas with and without feral dogs in Cayambe-Coca National Park in the northern Ecuadorian Andes using line transect surveys, camera traps, and track and sign surveys. In areas where feral dogs were present, four native mammals were absent: mountain coati (Nasuella olivacea), mountain paca (Cuniculus taczanowskii), long-tailed weasel (Mustela frenata), and northern pudu (Pudu mephistophiles). Relative abundances of six species were lower compared to areas without feral dogs: puma (Puma concolor), Andean fox (Lycalopex culpaeus), Andean bear (Tremarctos ornatus), striped hog-nosed skunk (Conepatus semistriatus), mountain tapir (Tapirus pinchaque), and little red brocket deer (Mazama rufina). Three species significantly altered activity patterns where feral dogs were present (Andean bear, mountain tapir, and little red brocket deer). In contrast, none of the native mammal species exhibited shifts in habitat use in areas with feral dogs. Dogs used all habitat types according to availability. Our results point to feral dogs as a significant problem for the native mammal community of this Andean region, and highlight the need to consider feral dogs as a potential threat to wildlife in other regions where anthropogenic effects appear to be low but feral dogs are present, particularly natural areas that contain endangered and endemic species.

Distribution and habitat use of invasive dogs in Colombia

Manjarrés Rodríguez, T. S. (2015). Distribución y uso de hábitat del perro (Canis familiaris) en la cuenca alta del río Otún (Risaralda-Colombia).Trabajo de grado presentado para optar al titulo de: Magister en Conservación y Uso de la Biodiversidad (Modalidad de investigación)
The dog (Canis familiaris) is a alien specie that when is present in natural areas get to interact with wildlife as a competitor, predator and transmitter of disease. The present study identified through the
tracking the dog abundance index and the dog selection of habitat types, its density with the probability density Kernel-ArcGis 10 and its potential distribution related with environmental
variables that limit or favor he dog presence through the MAXENT program. How results the dog
was found in both vegetation types studied (secondary forest and grassland). The dog got a high
density and abundance in the study area, surpassing the abundance of wildlife registered. The
Bonferroni interval showed that the dog and the fox (Cerdocyon thous) shared the same types of
habitat. The variables that favors their presence were the proximity to house and roads turning the
upper basin of the river Otun in vulnerable to the constant invasion of this specie.

Study shows impact of feral cats on lizards in Greek Islands

 Male of Erhard's Wall Lizard (Podarcis erhardii) . 

Credit: Jeroen Speybroeck/Wikipedia

A team of researchers with diverse backgrounds from universities in the U.S. and Greece has conducted a study of the impact of feral cats on Aegean wall lizards living in the Cyclades (Greek islands). In their paper published in Proceedings of the Royal Society B: Biological Sciences, the team describes behavior adaptations they observed in native lizards to the presence of feral cats.

Feral cats are domestic cats that are living in the wild—reports over the past several years have implicated them in a number of extinctions and declines of other species, particularly birds. Another type of creature impacted by feral cats is lizards—cats are known to kill them whether they eat them or not. In this new study, the research team ventured to the Thera, Kea and Naxos islands in the Cyclades—where cats were introduced by humans approximately 9,500 years ago—to learn more about how the native lizards have adapted to the introduced threat.

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Fatal toxoplasmosis in endemic NZ birds

Howe, L., Hunter, S., Burrows, E., & Roe, W. (2013). Four cases of fatal toxoplasmosis in three species of endemic New Zealand birds. Avian Diseases.  58(1): 171-175

Four cases of fatal toxoplasmosis in three endemic avian species are reported. Between 2009 and 2012, two kereru, one North Island brown kiwi, and one North Island kaka were submitted for necropsy examination. On gross post mortem the kiwi had marked hepatosplenomegaly while the kaka and two kereru had swollen, slightly firm deep red lungs. Histologically, there was extensive hepatocellular necrosis in the liver of the kiwi while the kaka and kereru showed severe fibrinous bronchointerstitial pneumonia. In the kiwi, protozoal organisms were present within both hepatocytes and Kupffer cells of the liver and within the epithelial cells and macrophages of the interstitium of the lung in the kaka and two kereru. The diagnosis of toxoplasmosis was confirmed with immunohistochemistry and PCR on the liver and/or lung of paraffin embedded formalin-fixed tissue. Genotyping of up to seven markers revealed an atypical Type II isolate of T. gondii was present in at least three of the cases. This study provides evidence that T. gondii can cause mortality in these endemic species and suggests further research is needed to determine that full extent of morbidity and mortality caused by this parasite in New Zealand's unique avifauna.

Dog predation on kiwis

Taborsky, M. (1988). Kiwis and dog predation: observations in Waitangi State Forest. Notornis, 35(3), 197-202.

A wild dog was found to kill 13 out of 23 kiwis marked with transmitters. 

The whole population may have lost 500 out of 900 birds, although this estimate may be conservative. The population will probably need 10-20 years and a rigorous protection scheme to recover to previous densities

Dogs among the main causes of death of blue penguins

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

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

Cat predation on Middle East wildlife

Brickner-Braun, I., Geffen, E., & Yom-Tov, Y. (2007). The domestic cat as a predator of Israeli wildlife. Israel Journal of Ecology & Evolution, 53(2), 129-142.

Predation of wildlife by domestic cats was studied in Israel. Analysis of stomach contents and data provided by observers revealed that many domestic cats enriched the diet provided by their owners with many species of wild animals, including 12 mammals, 26 birds, 18 reptiles, and one amphibian, and scavenged from garbage. The proportion of manufactured cat food and garbage dump food in the diet of urban cats decreased from 70% of stomach volume among those living in rural settlements to 44% among cats living in open areas, with the rest of the stomach contents consisting of wild animals. Of the wild animals hunted by cats, the most common category was mammals (75% of the stomach volume), followed by amphibians (10%), birds (9%), and reptiles (6%).

Most cats do not wander more than 200 m away from either a food source or cover. Female cats living in (southern) desert settlements do not leave the inhabited area and have very small home ranges, while those living in the Mediterranean region (central and northern) wander outside under the cover of trees and bushes and have significantly larger home ranges. The mean distance traveled daily by females from their center of activity was 51.3 m and 103.4 m for the southern and northern populations, respectively. Males were studied only in the Mediterranean region, and their travel distances were greater than those of females.

Although our results of predation are mainly qualitative, this study supports those done elsewhere in the world where the cat was shown to be a generalist predator whose potential impact on some species, especially endangered ones, may be considerable.

Little blue penguins killed by dogs

From http://www.stuff.co.nz
03/09/2014

At least eight little blue penguins were killed by dogs near Little Kaiteriteri Beach over the weekend, prompting a call for public help to keep the birds safe.Department of Conservation staff were devastated to find the dead birds, and are urging dog owners to be more vigilant.

Multiple kagu deaths caused by dogs

Hunt, G. R., Hay, R., & Veltman, C. J. (1996). Multiple Kagu Rhynochetos jubatus deaths caused by dog attacks at a high-altitude study site on Pic Ningua, New Caledonia. Bird Conservation International, 6(04): 295-306.

Dog predation has been cited as an important factor in the decline of the threatened Kagu of New Caledonia but direct evidence of predation was restricted to single kills. Here we report the first documented case of multiple Kagu deaths caused by dogs, which occurred at our 200 ha, high-altitude (800-1,300 m) study site on Pic Ningua. The deaths were discovered because we were radio-tracking Kagus there as part of our behavioural study on the birds. In 1993 we found 20 Kagus either dead (15) or wounded (5; one survived) from dog attacks in four distinct episodes over a 14-week period from late April to early August. Two other birds whose older remains were found also probably died from dog attacks. Of the 22 birds 18 wore radio transmitters; the four non-radio-tracked birds were found by chance. Dogs errant from a nearby tribal village were strongly implicated in carrying out most, if not all, of the attacks. They climbed around 1,000 m in altitude to reach the study site and attacked birds there on repeat visits to the site. The apparent recent disappearance of Kagus in forest neighbouring the study site suggests the dogs caused the deaths of most of the birds on the peak. Dog predation is probably an ongoing problem for the Kagu and the attacks at Pic Ningua are probably not an isolated incident. Protecting birds outside Riviere Bleue Park from dogs will require: (1) establishment of additional intensively managed reserves; (2) continuing education of the public and administrators about the need for Kagu protection and associated dog control; (3) involvement of tribal communities in Kagu conservation; and (4) enforcement of dog control laws. The events at Pic Ningua demonstrate the necessity for additional and non-connected reserves to safeguard against catastrophes and increase the probability of long-term Kagu persistence in the wild.

Low density feral cats cause local extirpation of small mammals in Australia

Frank, A.S.K, C.N. Johnson, J. M. Potts, A. Fisher, M. J. Lawes, J.C. Z. Woinarski, K. Tuft, I. J. Radford, I.J. Gordon, M.-A. Collis & S. Legge. 2014. Experimental evidence that feral cats cause local extirpation of small mammals in Australia's tropical savannas. Journal of Applied Ecology. doi: 10.1111/1365-2664.12323

Small mammal species are declining across northern Australia. Predation by feral cats Felis sylvestris catus is one hypothesised cause. Most evidence of cat impacts on native prey comes from islands, where cat densities are often high, but cats typically occur at low densities on mainland Australia.

We conducted a field experiment to measure the effect of predation by low-density cat populations on the demography of a native small mammal. We established two 12.5-ha enclosures in tropical savanna in the Northern Territory. Each enclosure was divided in half, with cats allowed access to one half but not the other. We introduced about 20 individuals of a native rodent, Rattus villosissimus, into each of the four compartments (two enclosures x two predator-access treatments). We monitored rat demography by mark-recapture analysis and radio-tracking, and predator incursions by camera surveillance and track and scat searches.

Rat populations persisted over the duration of the study (18 months) in the predator-proof treatment, where we detected no predator incursions, but declined to extinction in both predator-accessible compartments. In one case, cat incursions were frequently detected and the rat population was rapidly extirpated (< 3 months); in the other, cat incursions were infrequent, and the population declined more gradually (c. 16 month) due to low recruitment. We detected no incursions by dingoes Canis dingo, the other mammalian predator in the area.

Synthesis and applications. This is the first study to provide direct evidence that cats are capable of extirpating small mammals in a continental setting, in spite of their low population densities. This finding supports the hypothesis that predation by feral cats is contributing to declines of small mammals in northern Australia. The conservation management of native small mammals in northern Australia may require intensive control of cat populations, including large cat-free enclosures.

Human infrastructures and feral pets explain the distribution of native carnivores

Zapata G, Branch L, 2014. Evaluación de los factores determinantes de presencia – ausencia de los carnívoros en los Andes ecuatorianos. En: Cuesta F, Sevink J, Llambí LD, De Bièvre B, Posner J, Editores. Avances en investigación para la conservación de los páramos andinos, CONDESAN.

Carnivore surveys using scent stations, camera traps and reconnaissance surveys were carried out in five study areas in the northern Ecuadorian Andes. Nine species of carnivores are known to occur in the Ecuadorian Andes (puma, pampas cat, Andean fox, long-tailed weasel, Colombian weasel, striped hog-nosed skunk, mountain coati, neotropical river otter, and Andean bear).
A total of six species were recorded. The pampas cat, the Colombian weasel, and the Neotropical river otter were the three species that were not recorded. Data analysis suggests that the “distance to the nearest
house”, the “distance to roads”, and the “presence of exotic carnivore species” (feral cats and dogs) are the
most important variables that explain the presence of native carnivore species in the paramo ecosystem of northern Ecuador.

Introduced predators selectively culls medium-sized species from island mammal faunas

Hanna, E., & Cardillo, M. (2014). Predation selectively culls medium-sized species from island mammal faunas. Biology letters, 10(4), 20131066.

Globally, elevated extinction risk in mammals is strongly associated with large body size. However, in regions where introduced predators exert strong top-down pressure on mammal populations, the selectivity of extinctions may be skewed towards species of intermediate body size, leading to a hump-shaped relationship between size and extinction risk. The existence of this kind of extinction pattern, and its link to predation, has been contentious and difficult to demonstrate. Here, we test the hypothesis of a hump-shaped body size–extinction relationship, using a database of 927 island mammal populations. We show that the size-selectivity of extinctions on many islands has exceeded that expected under null models. On islands with introduced predators, extinctions are biased towards intermediate body sizes, but this bias does not occur on islands without predators. Hence, on islands with a large-bodied mammal fauna, predators are selectively culling species from the lower end of the size distribution, and on islands with a small-bodied fauna they are culling species from the upper end. These findings suggest that it will be difficult to use predictable generalizations about extinction patterns, such as a positive body size–extinction risk association, to anticipate future species declines and plan conservation strategies accordingly.

Cat impact in Madagascar forests

Farris, Z. J., Karpanty, S. M., Ratelolahy, F., & Kelly, M. J. (2014). Predator–Primate Distribution, Activity, and Co-occurrence in Relation to Habitat and Human Activity Across Fragmented and Contiguous Forests in Northeastern Madagascar. International Journal of Primatology, 1-22.

Predator–primate interactions are understudied, yet predators have been shown to influence primate behavior, population dynamics, and spatial distribution. An understanding of these interactions is important for the successful management and conservation of these species. Novel approaches are needed to understand better the spatial relationships between predators and primates across changing landscapes. We combined photographic surveys of predators and humans with line-transect sampling of lemurs across contiguous and fragmented forests in Madagascar to 1) compare relative activity; 2) estimate probability of occupancy and detection; 3) estimate predator–primate and local people–primate co-occurrence; and 4) assess variables influencing these parameters across contiguous and fragmented forests. In fragmented (compared to contiguous) forest sites endemic predator and lemur activity were lower whereas introduced predator and local people activity were higher. Our two-species interaction occupancy models revealed a higher number of interactions among species across contiguous forest where predator and lemur occupancy were highest. Mouse lemurs show evidence of “avoidance” (SIF < 1.0) with all predator species (endemic and introduced) in contiguous forest whereas white-fronted brown lemurs show “attraction” (SIF > 1.0) with feral cats and local people in contiguous forest. Feral cats demonstrated the highest number of interactions with lemurs, despite their distribution being limited to only contiguous forest. Distance to forest edge and distance to nearby villages were important in predicting predator occupancy and detection. These results highlight the growing threat to endemic predators and lemurs as habitat loss and fragmentation increase throughout Madagascar. We demonstrate the effectiveness of a novel combination of techniques to investigate how predator species impact primate species across a gradient of forest fragmentation.

Domestic cats outcompete endemic endangered Iriomote cat

Watanabe, S., Nakanishi, N., & Izawa, M. (2003). Habitat and prey resource overlap between the Iriomote cat Prionailurus iriomotensis and introduced feral cat Felis catus based on assessment of scat content and distribution. Mammal Study, 28(1), 47-56.

The Iriomote cat Prionailurus iriomotensis occurs only on Iriomote Island in the Ryukyu Archipelago of southern Japan. The population is estimated at 100 individuals and is on the decline. We examined resource overlap for prey and habitat between this species and introduced cats Felis catus by scat census and analysis of scat contents. The distribution of scats was completely different between the two species. The distribution of scats from Iriomote cats was associated with environmental factors such as vegetation types and terrain conditions, while the distribution of scats from feral cats mainly depended on locations of garbage dumps. Although the feral cat heavily utilized human rubbish, it also preyed upon thirteen species of native animals, ten of which were also used by Iriomote cats. From 1997 to 2001, the number of observed scats from Iriomote cats declined significantly, while feral cat scat became more common. Feral cats on Iriomote Island still depend on humans, but the expansion of their distribution into habitats of Iriomote cats may increase the competition for prey and habitat resources in the future.

3/4 spp of endemics on Amami preyed by feral dogs and cats

Okubo, C., Hirao, S., & Ishikawa, M. 2014. Quantifying predation by feral cats and dogs on threatened native mammals on Amami island, Japan. Singapore International Science Challenge Proceedings 2013

Amami Island, part of the Ryukyu Archipelago in Japan, is known for high levels of diversity and endemism. However, many species are now globally threatened with extinction, especially due to predation by feral animals. We surveyed prey species based on analysis of fecal samples of feral cats and dogs and present evidence that 74.3% of endemic species are being preyed upon. We investigated eating habits of feral cats and dogs in Amami Island by directly analyzing their droppings. Identification of prey animals was based on fur and bone fragments in droppings confirmed that many threatened species are consumed not only by feral dogs but also cats. Our study shows that the introduced animals are likely to adversely affect Amami’s terrestrial ecosystems.

Toxoplasmosis risk to sea-otters

Seventeen percent of sea otters die from brain disease caused by a single-cell deadly parasite, Toxoplasma gondii. For eons, this parasite has moved mostly without notice among animals, including humans, on land. But now, it is migrating to the sea, where it is infecting mammals, including sea otters, whose immune systems are unprepared for the assault.

Toxoplasmosis and sea otters

Parasite Shed in Cat Feces Kills Sea Otters

Conrad, P. (2007). Parasite Shed in Cat Feces Kills Sea Otters. Healthy Marine Ecosystems • November 2006

Endangered sea otters in California have been found to suffer lethal infections from a parasite, Toxoplasma gondii, shed in cat feces. These infections may be a factor contributing to the marine mammal’s slow recovery from near extinction.

Toxoplasma gondii is a protozoan parasite that attacks an otter’s brain tissue, causing lesions, depression, convulsions and death.

Because cats are the only animals known to shed Toxoplasma gondii, runoff must be carrying cat feces and the parasite to the coast. From there, it is not clear how otters are getting sick. One possibility is that they are ingesting infected mussels or other filter-feeding bivalves, which accumulate pathogens in their tissues.

The parasite is usually harmless to healthy people. The exception is pregnant women, whose fetuses can develop toxoplasmosis, hence the advice for pregnant women to avoid cleaning cat litter boxes.

Once numbering more than 300,000, southern sea otters were hunted to near extinction in the 19th century for their lush pelts. They were granted protection under the Endangered Species Act in 1977, when their numbers were about 1,789. In the mid-1990s, their recovery staggered and concerns were raised about the animal’s long-term prospects. More recently their numbers seem to be rising.

Observers tallied a total of 2,692 California sea otters for the 2006 spring survey, compared with 2,100 in 2002 and 2,377 in 1995.

Feeding cats deplates native fauna

Hawkins, C.C., W.E. Grant & M.T. Longnecker. 1999. Effect of subsidized house cats on California birds and rodents. Transactions of the Western Section of The Wildlife Society, 35: 29-33

Cat advocates are establishing feeding stations in public parks, often claiming that well-fed cats pose little threat to wildlife. This claim was tested east of San Francisco, California, in a cat area and a no-cat area. In 1995, more harvest mice were trapped in the no-cat area. In 1996, more harvest mice (Reithrodontomys megalotis) and deer mice (Peromyscus sp.) were trapped in the no-cat area, and more house mice were trapped in the cat area. The numbers of trapped California meadow voles (Microtus californicus) were not different between the areas in either year. More native rodents were trapped in the no-cat area. Birds present during the breeding season were seen more often in the no-cat area. California quail (Callipepla californicus) and California thrashers (Toxostoma redivivum) were present in the no-cat area and absent in the cat area. Cats at artificially high densities, sustained by supplementary feeding, reduced the abundance or native rodent and bird populations, changed the rodent species composition, and may have facilitated the expansion of the house mouse into new areas. Thus we recommend that the feeding of cats in parks should be strictly prohibited. 

The cats of Herekopare

Fitzgerald, B. M., & Veitch, C. R. (1985). The cats of Herekopare Island, New Zealand; their history, ecology and affects on birdlife. New Zealand Journal of Zoology, 12(3), 319-330.

House cats (Felis catus) were introduced to Herekopare Island, a mammal-free island of about 28 ha near Stewart Island, in about 1925. In winter 1970, the total population of 33 cats (20 males, 13 females) — a density of 1.2 cats/ha — was killed, mainly by trapping. Examination of stomach contents and scats showed that the cats fed mainly on petrels, supplemented by land birds and insects. The bird life of Herekopare Island was studied by H. Guthrie-Smith in 1911, L. E. Richdale in the early 1940s, and by New Zealand Wildlife Service staff in 1968 and 1970. Their accounts indicate that a vast breeding population of diving petrels and thousands of broad-billed prions were probably exterminated by the cats, though fairy prions and sooty shearwaters persisted. Among land birds, the yellow-crowned parakeet, robin, fernbird, brown creeper, Stewart Island snipe, and banded rail were exterminated. Two other species, the red-crowned parakeet and tomtit, probably disappeared but subsequently recolonised the island. Although cats had the greatest influence on the bird life over this period, wekas, which were present for some years, together with changes in the vegetation, may have affected some bird populations.