Feral cat eradication in the presence of endemic San Nicolas Island foxes

Hanson, C. C., Jolley, W. J., Smith, G., Garcelon, D. K., Keitt, B. S., Little, A. E., & Campbell, K. J. (2014). Feral cat eradication in the presence of endemic San Nicolas Island foxes. Biological Invasions, 1-10.

Projects to eradicate invasive species from islands are a high priority for conservation. Here we describe the process used to successfully eradicate an introduced carnivore on an island where a native carnivore of similar size was also present. We primarily used padded leg-hold live trapping to capture feral cats (Felis silvestris catus). Trapped feral cats were transported off-island and housed in a permanent enclosure on the continent. We used additional methods, such as tracking dogs and spotlight hunting, to detect and remove more-difficult individuals. Project implementation caused no significant negative impacts to the endemic San Nicolas Island fox (Urocyon littoralis dickey) population. Mitigation measures included on-site veterinary resources, modified padded leg-hold live traps, conditioned trap aversion, a trap monitoring system and personnel training. To confirm eradication, we utilized camera traps and sign search data in a model to predict project success. A key part of the success of this project was the partnerships formed between NGOs, and government organizations. With support from the partnership, the use of innovative technology to improve traditional trapping methods allowed feral cats to be removed effectively in the presence of a native species occupying a similar niche. This project shows that strong partnerships, innovative methods, and use of technology can provide the conditions to eradicate invasive species when major barriers to success exist.

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.

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.

Feral cats on Stewart Island and their effects on kakapo

Karl, B. J., & Best, H. A. (1982). Feral cats on Stewart Island; their foods, and their effects on kakapo. New Zealand journal of zoology, 9(2), 287-293.

Kakapo

The foods of feral house cats (Felis catus) on Stewart Island were determined by examining 229 scats collected during surveys of the distribution and numbers of kakapo (Strigops habroptilus), an endangered ground-parrot species. Rats occurred in 93% of the scats, birds in 44. 1%, wetas (large orthopterans) in 26.2%, and lizards in 24.0%. Twelve (70.6%) of the 17 species of birdswere native. Kakapo remains were found in 6 (5.1%) of the 118 scats collected from areas where kakapo have been recorded.

Feral cats threaten endemic Barau's Petrel

Faulquier, L., Fontaine, R., Vidal, E., Salamolard, M., & Le Corre, M. (2009). Feral Cats Felis catus Threaten the Endangered Endemic Barau's Petrel Pterodroma baraui at Reunion Island (Western Indian Ocean). Waterbirds,32(2), 330-336.

Cats (Felis catus) were probably introduced to Reunion Island (Western Indian Ocean) in the seventeenth century and feral populations are now spread over all anthropogenic and native habitats. The diet of feral cats living in the breeding habitat of Barau's Petrel (Pterodroma baraui), an endemic and threatened seabird of Reunion Island, were studied. Results from the analysis of 217 scat (333 prey items) showed that Barau's Petrel were the most common prey of feral cats, followed by introduced rodents. Numerous dead birds at breeding colonies that had been killed by cats were found, 58% of the birds were adults. Given the high sensitivity of the population growth rate of a long-lived seabird to any additive mortality of adults, these results are particularly worrying. As this species is also threatened by massive light-induced mortality of fledglings, it is highly likely that this population is declining. A control of cats at breeding colonies is urgently needed to save this species from extinction.

Pinet, P., Salamolard, M., Probst, J.M., Russell, J.C., Jaquemet, S. & Le Corre, M. 2009. Barau’s Petrel Pterodroma baraui: history, biology and conservation of an endangered petrel. Marine Ornithology 37: 107–113.

The Barau’s petrel Pterodroma baraui is an endangered gadfly petrel endemic to Reunion Island. It nests in pristine cloud forests between 2200 m and 2800 m above sea level. Although locally abundant, this species is one of the least-studied seabirds in the world. The lack of basic biological information constrains effective conservation action. In this paper, we compile information on past and present status and distribution, ecology, threats and conservation actions. The objectives were to: (i) summarize current knowledge and identify major gaps, (ii) outline major threats to Barau’s Petrel and (iii) propose management actions to mitigate those threats. Critical gaps in our knowledge include (i) a lack of precise demographic parameters, (ii) the exact distribution of this species at sea and the factors that influence it, and (iii) habitat requirements associated with nesting. Barau’s Petrel is classified endangered (International Union for Conservation of Nature Red List 2008). The major threats include, in order of importance, predation by alien mammals, light-induced mortality and modification of nesting habitat. These threats affect the various age classes of the population (eggs, chicks, juveniles and adults) differently. A recent modelling exercise suggested the extinction of Barau’s Petrel in fewer than 100 years, attributable to feral cat predation at breeding colonies in the absence of cat control. The recent establishment of a National Park on Reunion Island should unify conservation and research actions, and prioritise controlling feral cats in breeding colonies. This control should commence as soon as possible in association with a dedicated education program on the effects of feral cats on the Barau’s Petrel population.

Socorro island's endemics and cats

Arnaud, G., A. Rodriguez, A. Ortega-Rubio, S. Alvarez-Cardenas. 1993. Predation by Cats on the Unique Endemic Lizard of Socorro Island (Urosaurus auriculatus), Revillagigedo, Mexico. Ohio Journal of Science, 93 (4): 101-103

During 1990 the distributions of the endemic lizard (Urosaurus auriculatus) and the feral cat (Felis catus) of Socorro Island were observed and scats of the last species were collected. A total of 46 cat scats were analyzed, showing that lizards were an important prey item, varying in frequency from 33.33% in February to 66.66% in November. Because of the impact of sheep (Ovis aries) on the natural vegetation and because of the impact of cat predation, we recommend that a plan be developed for the removal of exotic species and the restoration of natural vegetation to Socorro Island.

Jehl, J.R.& K.C. Parks. 1983. 'Replacements' of landbird species on Socorro Island, Mexico. Auk 100: 551-559.
The endemic dove Zenaida graysoni of Socorro Island, an oceanic island in the Pacific south of Baja California, became extirpated between 1958 and 1978 and the endemic mockingbird Mimodes graysoni diminished during the same years and was approaching extinction by 1981. The mainland mourning dove Z. macroura became established on Socorro between (probably) 1971 and 1978 and the mainland northern mockingbird Mimus polyglottos between 1978 and 1981. Superficially an instance of replacement of island endemics by mainland relatives through competitive exclusion, the case is actually more complicated. It is argued that extermination of the endemics was probably caused by predation by feral cats introduced in 1957 or later. There is no evidence of any actual competition between the pairs of species and their preferred habitats overlap only slightly. The nearly concurrent establishment of the 2 invading species, known to have occurred frequently as casual visitors to Socorro and other islands is attributed largely to the provision of fresh water made available as a result of human settlement. Simple comparison of island species lists compiled at intervals is an inadequate base for theories of island species turnover.

More info about Socorro's threatened birds:
BirdLife International (2013) Species factsheet: Zenaida graysoni. Downloaded from http://www.birdlife.org on 12/04/2013.
BirdLife International (2013) Species factsheet: Mimus graysoni. Downloaded from http://www.birdlife.org on 12/04/2013. 

BirdLife International (2013) Species factsheet: Aratinga brevipes. Downloaded from http://www.birdlife.orgon 12/04/2013.
BirdLife International (2013) Species factsheet: Troglodytes sissonii. Downloaded from http://www.birdlife.orgon 12/04/2013.
BirdLife International (2013) Species factsheet: Puffinus auricularis. Downloaded from http://www.birdlife.orgon 12/04/2013.