Les hommes ont oublié cette vérité. Mais tu ne dois pas l'oublier, dit le renard. Tu deviens responsable pour toujours de ce que tu as apprivoisé.
Le Petit Prince, chap. 21
Showing posts with label Polynesia. Show all posts
Showing posts with label Polynesia. Show all posts

Sunday, 21 December 2014

Cat eating endangered honeycreeper





The non-native feral cat in Hawaii is the most threatening predator to critically endangered palila. Palila did not evolve with these predators and are especially vulnerable to them. Evidence of their vulnerability was documented by researchers studying nest success of palila using continuous-loop video cameras to monitor the nests. Based on predation rates of the nests monitored, feral cats cause about 10% of all palila nests to fail every year.

Nest predation on endangered Hawaiian honeycreeper

Laut, M. E., Banko, P. C., & Gray, E. M. (2003). Nesting behavior of Palila, as assessed from video recordings. Pacific science, 57(4), 385-392.

We quantified nesting behavior of Palila (Loxioides bailleui), an endangered Hawaiian honeycreeper, by recording at nests during three breeding seasons using a black-and-white video camera connected to a videocassette recorder. A total of seven nests was observed. We measured the following factors for daylight hours: percentage of time the female was on the nest (attendance), length of attendance bouts by the female, length of nest recesses, and adult provisioning rates. Comparisons were made between three stages of the 40-day nesting cycle: incubation (day 1–day 16), early nestling stage (day 17–day 30 [i.e., nestlings ≤14 days old]), and late nestling stage (day 31–day 40 [i.e., nestlings > 14 days old]). Of seven nests observed, four fledged at least one nestling and three failed. One of these failed nests was filmed being depredated by a feral cat (Felis catus). Female nest attendance was near 82% during the incubation stage and decreased to 21% as nestlings aged. We did not detect a difference in attendance bout length between stages of the nesting cycle. Mean length of nest recesses increased from 4.5 min during the incubation stage to over 45 min during the late nestling stage. Mean number of nest recesses per hour ranged from 1.6 to 2.0. Food was delivered to nestlings by adults an average of 1.8 times per hour for the early nestling stage and 1.5 times per hour during the late nestling stage and did not change over time. Characterization of parental behavior by video had similarities to but also key differences from findings taken from blind observations. Results from this study will facilitate greater understanding of Palila reproductive strategies.

Friday, 19 December 2014

Videographic evidence of endangered species depredation by feral cat in Hawaii

Judge, S., Lippert, J. S., Misajon, K., Hu, D., & Hess, S. C. (2012). Videographic evidence of endangered species depredation by feral cat. Pacific Conservation Biology, 18(4), 293.

Feral cats (Felis catus) have long been implicated as nest predators of endangered 'Ua'u (Hawaiian Petrel; Pterodroma sandwichensis) on Hawai'i Island, but until recently, visual confirmation has been limited by available technology. 'Ua'u nest out of view, deep inside small cavities, on alpine lava flows. During the breeding seasons of 2007 and 2008, we monitored known burrows within Hawai'i Volcanoes National Park. Digital infrared video cameras assisted in determining the breeding behaviour and nesting success at the most isolated of burrows. With 7 cameras, we collected a total of 819 videos and 89 still photographs of adult and nestling 'Ua'u at 14 burrows. Videos also confirmed the presence of rats (Rattus spp.) at 2 burrows, 'Oma'o (Myadestes obscurus) at 8 burrows, and feral cats at 6 burrows. A sequence of videos showed a feral cat taking a downy 'Ua'u chick from its burrow, representing the first direct evidence of 'Ua'u depredation by feral cat in Hawai'i. This technique provides greater understanding of feral cat behaviour in 'Ua'u colonies, which may assist in the development of more targeted management strategies to reduce nest predation on endangered insular bird species.

Wednesday, 17 December 2014

Comparison of managed and unmanaged wedge-tailed shearwater colonies: Effects of predation

Smith, D. G., Polhemus, J. T., & VanderWerf, E. A. (2002). Comparison of managed and unmanaged wedge-tailed shearwater colonies on O'ahu: Effects of predation. Pacific Science, 56(4), 451-457.

On O‘ahu, Wedge-tailed Shearwaters (Puffinus pacificus) and other seabirds nest primarily on small offshore islets, but fossil evidence shows that many seabirds formerly bred on O‘ahu itself. Predation by introduced mammals is suspected to be the primary factor preventing shearwaters and other seabirds from reestablishing large nesting colonies on O‘ahu. We investigated the effects of predation on Wedge-tailed Shearwaters by comparing three small unmanaged colonies at Mālaekahana State Recreation Area on O‘ahu, where feral cats are fed by the public, with a large managed colony at nearby Moku‘auia Island State Seabird Sanctuary, where predators are absent. During three visits on 19 April, 16 June, and 23 October 2000, we located 69 occupied burrows in three colonies at Mālaekahana and 85 occupied burrows in four monitoring plots at Moku‘auia. Many more nests produced chicks at Moku‘auia (62%) than at Mālaekahana (20%). Among plots at Ma¯laekahana, reproductive success was lowest (zero) at the colony closest to the cat feeding site. In addition, 44 adult shearwater carcasses were found at Mālaekahana near the cat feeding site. Predation, most likely by cats attracted to supplemental food, had a devastating impact on shearwaters at Mālaekahana. At one colony there was complete reproductive failure and almost all adults were killed. Populations of long-lived species like seabirds are sensitive to adult mortality, and Ma¯laekahana may act as a sink, draining birds away from other areas.

Tuesday, 16 December 2014

Mongooses may be more dangerous predator than cats to burrowing seabirds

DUFFY, D. C. & CAPECE, P.I. 2014. Depredation of endangered burrowing seabirds in Hawai’i: management priorities. Marine Ornithology 42: 149–152.

Small Indian Mongooses Herpestes javanicus have until recently been absent from the island of Kaua’i, Hawai’i. In anticipation of required management, we examine evidence that mongooses may be a significantly more dangerous predator than cats Felis catus for burrowing seabirds, particularly the endangered Hawaiian Petrel Pterodroma sandwichensis and threatened Newell’s Shearwater Puffinus newelli. Mongooses are small enough to enter burrows, allowing them to take eggs, nestlings and adults. In contrast, cats appear too broad to enter any but the widest burrows, so they tend to attack adults and young when these come to the burrow mouth. Given that these seabird species no longer persist in any numbers at low elevations on islands where mongooses are present, and that Kaua’i is one of the lowest of the main Hawaiian islands, if resources are limited, local control or eradication of mongooses would be a higher priority for management than control of cats or rats Rattus spp., although control of just one predator might result in increases in the others. The most important management action is to keep mongooses off islands where they are not already established.

Sunday, 28 April 2013

Structure of a cat population on Hawai'i islands

Danner, R.M., C. Farmer, S.C. Hess, R.M. Stephens & P.C. Banko. 2010. Survival of Feral Cats, Felis catus (Carnivora: Felidae), on Mauna Kea, Hawai‘i, Based on Tooth Cementum Lines. Pacific Science, 64 (3): 381–389

Feral cats (Felis catus) have spread throughout anthropogenic and insular environments of the world. They now threaten many species of native wildlife with chronic depredation. Knowledge of feral cat population dynamics is necessary to understand their ecological effects and to develop effective control strategies. However, there are few studies worldwide regarding annual or lifetime survival rates in remote systems, and none on Pacific islands. We constructed the age distribution and estimated survival of feral cats in a remote area of Hawai‘i Island using cementum lines present in lower canine teeth. Our data suggest annual cementum line formation. A log-linear model estimated annual survival ≥1 yr of age to be 0.647. Relatively high survival coupled with high reproductive output allows individual cats to affect native wildlife for many years and cat populations to rebound quickly after control efforts.

Wednesday, 10 April 2013

Cats' diet on some Pacific islands

Jarvis and Howlnad
R.D. Kirkpatrick and Mark J. Rauzon. 1986. Foods of Feral Cats Felis catus on Jarvis and Howland Islands, Central Pacific Ocean. Biotropica, 18 (1): 72-75

Food habits of feral cats (Felis catus) were studied on two small uninhabited islands in the central Pacific Ocean. Cat stomach contents, collected on Howland Island in May 1979 and on Jarvis Island during May 1979 and June-July 1982, revealed that sooty terns (Sterna fuscata) were the primary prey species. Other seabirds, lizards, insects and, on Jarvis Island, house mice were also eaten. Fetal cats may have virtually exterminated the wedge-tailed shearwater colony on Jarvis Island.

Kermadec
Fitzgerald, B.M.; Kark, B.J. & Veitch, C.R. 1991. The diet of feral cats (Felis catus) on Raoul Island, Kermadec Group. New Zealand Journal of Ecology 15(2): 123-129.

Feral cats became established on Raoul Island some time between 1836 and 1872; the prey available to them included a great variety of nesting seabirds, few of which are present now, landbirds and kiore (Rattus
exulans). Norway rats reached the island in 1921, providing additional prey for cats, but also another potential predator of seabirds. The diet of cats is described from guts and scats collected between 1972 and 1980. Rats are the main food, with land birds second in importance, and seabirds are now a minor item. More than 90% of the rats eaten by cats are kiore although more Norway rats than kiore are trapped. Eradicating cats from Raoul Island is feasible but because Norway rats too are important predators of birds on islands, it is likely that eradicating cats without also eradicating Norway rats will do little to restore the diversity of bird species on Raoul Island, although the densities of a few species now present might be increased.

Hawai'i
Hess, S. C.; Hansen, H.; Nelson, D.; Swift, R. & Banko, P. C. 2007. Diet of feral cats in Hawai'i Volcanoes National Park. Pacific Conservation Biology, 13: 244–249.
We documented the diet of feral cats by analysing the contents of 42 digestive tracts from Kilauea and Mauna Loa in Hawai'i Volcanoes National Park. Small mammals, invertebrates, and birds were the most common prey types consumed by feral cats. Birds occurred in 27.8-29.2% of digestive tracts. The total number of bird, small mammal, and invertebrate prey differed between Kilauea and Mauna Loa. On Mauna Loa, significantly more (89%) feral cats consumed small mammals, primarily rodents, than on Kilauea Volcano (50%). Mice (Mus musculus) were the major component of the feral cat diet on Mauna Loa, whereas Orthoptera were the major component of the diet on Kilauea. We recovered a mandible set, feathers, and bones of an endangered Hawaiian Petrel (Pterodroma sandwichensis) from a digestive tract from Mauna Loa. This specimen represents the first well-documented endangered seabird to be recovered from the digestive tract of a feral cat in Hawai'i and suggests that feral cats prey on this species.

Smucker, T. D., G. D. Lindsey, & S. M. Mosher. 2000. Home range and diet of feral cats in Hawaii forests. Pacific Conservation Biology 6: 229–237.
Feral cat Felis catus home range in a Hawaiian montane wet forest and their diet in three habitats - montane wet forest, subalpine dry forest, and lowland dry forest - were determined to provide baseline ecological data and to assess potential impacts to native terrestrial fauna. Seven cats (three males and four females) were captured in 624 trap nights. Mean weight of adult cats was 2.85 0.27 (SE) kg for males and 1.87 0.03 kg for females. Mean diurnal home range using the adaptive kernel method was 5.74 2.73 km2 for three males and 2.23 0.44 km for two females. Daytime locations were always within the montane wet forest with the borders on one or more sides of the home ranges of all cats defined by open grassland pastures. Rodents comprised the majority of the cat diets in all three habitats, with the frequencies of occurrence between 0.88 and 0.91. Bird remains were a regular component of the diet of cats, with montane wet forest having the highest frequency of occurrence (0.68), followed by subalpine dry forest (0.53). and lowland dry forest (0.21).

Trap-Neuter-Release vs. Trap-Euthanasia

Lohr, C. A., Cox, L. J. & Lepczyk, C. A. (2013), Costs and Benefits of Trap-Neuter-Release and Euthanasia for Removal of Urban Cats in Oahu, Hawaii. Conservation Biology, 27: 64–73. 

Our goal was to determine whether it is more cost-effective to control feral cat abundance with trap-neuter-release programs or trap and euthanize programs. Using STELLA 7, systems modeling software, we modeled changes over 30 years in abundance of cats in a feral colony in response to each management method and the costs and benefits associated with each method . We included costs associated with providing food, veterinary care, and microchips to the colony cats and the cost of euthanasia, wages, and trapping equipment in the model. Due to a lack of data on predation rates and disease transmission by feral cats the only benefits incorporated into the analyses were reduced predation on Wedge-tailed Shearwaters (Puffinus pacificus). When no additional domestic cats were abandoned by owners and the trap and euthanize program removed 30,000 cats in the first year, the colony was extirpated in at least 75% of model simulations within the second year. It took 30 years for trap-neuter-release to extirpate the colony. When the cat population was supplemented with 10% of the initial population size per year, the colony returned to carrying capacity within 6 years and the trap and euthanize program had to be repeated, whereas trap-neuter-release never reduced the number of cats to near zero within the 30-year time frame of the model. The abandonment of domestic cats reduced the cost effectiveness of both trap-neuter-release and trap and euthanize. Trap-neuter-release was approximately twice as expensive to implement as a trap and euthanize program. Results of sensitivity analyses suggested trap-neuter-release programs that employ volunteers are still less cost-effective than trap and euthanize programs that employ paid professionals and that trap-neuter-release was only effective when the total number of colony cats in an area was below 1000. Reducing the rate of abandonment of domestic cats appears to be a more effective solution for reducing the abundance of feral cats.


Costos y Beneficios de Captura-Esterilización-Liberación y Eutanasia para la Remoción de Gatos Urbanos en Oahu, Hawaii

Nuestra meta fue determinar si es más rentable controlar la abundancia de gatos ferales con programas de captura-esterilización-liberación o con programas de captura y eutanasia. Utilizando STELLA 7, software para modelar sistemas, modelamos cambios a lo largo de 30 años en la abundancia de gatos en una colonia feral en respuesta a cada método de manejo, así como de los costos y beneficios asociados con cada uno. En el modelo incluimos los costos asociados con la alimentación, el cuidado veterinario y los microchips para la colonia de gatos y el costo de la eutanasia, los salarios y el equipo de captura. Debido a la falta de datos sobre las tasas de depredación y de transmisión de enfermedades por gatos ferales, la reducción de la depredación sobre Puffinus pacificus fueron los únicos beneficios incorporados en el análisis. Cuando no hubo abandono adicional de gatos por sus dueños y el programa de captura y eutanasia removió 30,000 gatos en el primer año, la colonia fue extirpada en por lo menos 75% de las simulaciones del modelo en el segundo año. Tomó 30 años para que la captura-esterilización-liberación extirpara la colonia. Cuando la población de gatos fue suplementada con 10% del tamaño poblacional inicial por año, la colonia regresó a la capacidad de carga en 6 años y se tenía que repetir el programa de captura y eutanasia, mientras que la captura-esterilización-liberación nunca redujo el número de gatos a casi cero en los 30 años del marco de tiempo del modelo. El abandono de gatos domésticos redujo la rentabilidad tanto de la captura-esterilización-liberación como de la captura y eutanasia. La implementación de la captura-esterilización-liberación costó casi el doble que el programa de captura y eutanasia. Los resultados de los análisis de sensibilidad sugirieron que los programas de captura-esterilización-liberación que emplean voluntarios son aun menos rentables que los programas de captura y eutanasia que emplean profesionales pagados y que la captura-esterilización-liberación solo fue efectiva cuando el número total de gatos en un área era menor a 1000. La reducción de la tasa de abandono de gatos domésticos parece ser una solución más efectiva para reducir la abundancia de gatos ferales.

Tuesday, 9 April 2013

Toxoplasmosis affecting endangered native Hawaiian bird

Work,T.M.,  J. G. Massey, B.A. Rideout, C.H. Gardiner, D. B. Ledig, O. C. H. Kwok & J. P. Dubey. 2000. Fatal toxoplasmosis in free-ranging endangered 'Alala from Hawaii. Journal of Wildlife Diseases, 36(2): 205–212

The ‘Alala (Corvus hawaiiensis) is the most endangered corvid in the world, and intensive efforts are being made to reintroduce it to its former native range in Hawaii. We diagnosed Toxoplasma gondii infection in five free-ranging ‘Alala. One ‘Alala, recaptured from the wild because it was underweight and depressed, was treated with diclazuril (10 mg/kg) orally for 10 days. Antibodies were measured before and after treatment by the modified agglutination test (MAT) using whole T. gondii tachyzoites fixed in formalin and mercaptoethanol. The MAT titer decreased four-fold from an initial titer of 1:1,600 with remarkable improvement in physical condition. Lesions of toxoplasmosis also were seen in two partially scavenged carcasses and in a third fresh intact carcass. Toxoplasma gondii was confirmed immunohistochemically by using anti-T. gondii specific serum. The organism was also cultured by bioassay in mice from tissues of one of these birds and the brain of a fifth ‘Alala that did not exhibit lesions. The life cycle of the parasite was experimentally completed in cats. This is the first record of toxoplasmosis in ‘Alala, and the parasite appears to pose a significant threat and management challenge to reintroduction programs for ‘Alala in Hawaii.
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