Cats and Tropci birds

Boeken, M. (2016). Breeding success of Red-billed Tropicbirds Phaethon aethereus on the Caribbean island of Saba. Ardea, 104(3), 263-271.

In 2011 and 2012 the breeding success of Red-billed Tropicbirds Phaethon aethereus mesonauta was monitored on Saba, a 13-km2 island in the Caribbean Netherlands. The two colonies on the south and south-west side of the island both contain approximately 100–300 nests; breeding success was zero at these sites, due to predation of newly hatched chicks by Feral House Cats. In the single large colony of Old Booby Hill (estimated to contain approximately 1000 nests) on the east side of the island, rates of predation were lower, resulting in a breeding success (survival from laying until fledging, as far as observed) of 65%. Calculations of daily survival of eggs and chicks following Mayfield, resulted in a nesting success of 48% per pair. I conservatively estimated the size of the Saba breeding population to be at least 1300–1500 pairs, which is larger than the previous estimate of 750–1000 pairs. Potentially, the number of breeding pairs may be as high as 1850 pairs.

Feral cat killing chick and adult of endangered Newell's Shearwater

Kaua'i Endangered Seabird Recovery Project

A feral cat in Hono o Na Pali NAR killing first an endangered Newell's Shearwater chick and then the adult - in an area with ongoing introduced predator control. Warning : Graphic Content, this is not pleasant viewing. However it needs to be shown to illustrate the serious conservation impact of feral cats in the wilds of Kaua'i.

Monitoring feral cats' movements at important seabird colony

Bonnaud, E., Berger, G., Zarzoso-Lacoste, D., Bourgeois, K., Palmas, P., & Vidal, É. (2015). First steps in studying cat movement behaviour through VHF tracking at a major world breeding site for the Mediterranean endemic Yelkouan shearwater. Revue d'Ecologie, 70 (12)

Cats are considered one of the most harmful invasive predators of island native species, particularly adult shearwaters, which are highly vulnerable to predation. Populations of Yelkouan shearwater, an endemic species of the Mediterranean basin with only a few large breeding colonies, are predicted to decline in response to feral or free-roaming cats. In a previous study, the impact of introduced cats on the Yelkouan shearwater population of Le Levant Island was assessed through the analysis of cat diet over a two-year period. The study showed that cats prey upon three staple species: rabbits, rats, and shearwaters, with a peak of predation on shearwaters immediately upon their arrival at colonies (prospecting period). Here, we supplement this previous work by conducting a preliminary study on the movement patterns of four free-roaming cats (three feral and one domestic) using very high frequency (VHF) tracking to analyse individual behaviour and home ranges on Le Levant Island, one of the Yelkouan shearwater’s major breeding sites. Our results show that two of the three feral cats were recorded inside and in close vicinity to the shearwater colonies, mainly during the prospecting period, while the domestic cat was never recorded inside the colonies. This suggests that some feral cats could show movement behavioural patterns linked to the shearwater presence as soon as these seabirds arrive at the colonies. The monitored domestic cat also showed a relatively small home range, while feral cats covered larger distances and with overlapping territories. Based on these preliminary results of cat movement behaviour, in addition to the previous results of cat predation, it is evident that cat impact must be reduced. This may be achieved through accurate management strategy that takes cat movement behaviour into account to avoid exhausting one of the most important breeding sites for this Mediterranean endemic species

Studying cat movement behaviour through VHF tracking on Mediterranean island

Bonnaud, E., Berger, G., Zarzoso-Lacoste, D., Bourgeois, K., Palmas, P., & Vidal, É. (2015). First steps in studying cat movement behaviour through VHF tracking at a major world breeding site for the Mediterranean endemic Yelkouan shearwater. Revue d'Écologie, 70  Sup.12

Le chat représente un des prédateurs invasifs les plus menaçants pour les espèces natives des îles et particulièrement pour les oiseaux marins adultes qui sont fortement vulnérables à la prédation. Les populations du Puffin Yelkouan, espèce endémique du bassin méditerranéen, sont réparties en quelques grandes colonies de reproduction et sont en voie de déclin, notamment du fait de l’impact des chats harets et errants. Dans une étude précédemment publiée, l’impact des chats introduits sur la population de puffins de l’île du Levant a été évalué au travers du régime alimentaire du chat sur une période de deux ans. Cette étude a mis en évidence que les chats consommaient trois proies principales : le Lapin, le Rat noir et le Puffin Yelkouan, et qu’un pic de prédation de puffins était observé dès leur arrivée sur les colonies (période de prospection). Nous avons donc cherché à compléter ce travail par une étude préliminaire visant à étudier les patrons de mouvement de quatre chats (trois chats harets et un chat domestique) via un suivi VHF (very high frequency), dans le but d’analyser leurs comportements individuels et leurs domaines vitaux sur l’île du Levant, qui est l’un des principaux sites de reproduction du Puffin Yelkouan. Nos résultats montrent que deux des trois chats harets ont été détectés dans les colonies de puffins durant les périodes de prospection et de reproduction de cet oiseau marin alors que le chat domestique n’a jamais été détecté dans ces colonies. Cela suggère que les patrons de déplacement des quatre chats suivis puissent être liés à la présence des puffins dès que ces oiseaux marins arrivent à la colonie. Les chats suivis montrent des domaines vitaux de taille relativement réduite, plus larges pour les chats harets qui couvrent de plus grandes distances, et avec des territoires chevauchants, que pour le chat domestique. Ces résultats préliminaires de patrons de déplacements, couplés aux résultats précédents de prédation du chat sur le Puffin Yelkouan, nous indiquent que l’impact du chat haret se doit d’être limité. Cet objectif doit être atteint en effectuant une stratégie de gestion efficace qui tiendrait compte des patrons de déplacements des chats afin d’éviter l’épuisement d’un des sites de reproduction les plus importants pour cette espèce de puffin endémique de Méditerranée


Cats are considered one of the most harmful invasive predators of island native species, particularly adult shearwaters, which are highly vulnerable to predation. Populations of Yelkouan shearwater, an endemic species of the Mediterranean basin with only a few large breeding colonies, are predicted to decline in response to feral or free-roaming cats. In a previous study, the impact of introduced cats on the Yelkouan shearwater population of Le Levant Island was assessed through the analysis of cat diet over a two-year period. The study showed that cats prey upon three staple species: rabbits, rats, and shearwaters, with a peak of predation on shearwaters immediately upon their arrival at colonies (prospecting period). Here, we supplement this previous work by conducting a preliminary study on the movement patterns of four free-roaming cats (three feral and one domestic) using very high frequency (VHF) tracking to analyse individual behaviour and home ranges on Le Levant Island, one of the Yelkouan shearwater’s major breeding sites. Our results show that two of the three feral cats were recorded inside and in close vicinity to the shearwater colonies, mainly during the prospecting period, while the domestic cat was never recorded inside the colonies. This suggests that some feral cats could show movement behavioural patterns linked to the shearwater presence as soon as these seabirds arrive at the colonies. The monitored domestic cat also showed a relatively small home range, while feral cats covered larger distances and with overlapping territories. Based on these preliminary results of cat movement behaviour, in addition to the previous results of cat predation, it is evident that cat impact must be reduced. This may be achieved through accurate management strategy that takes cat movement behaviour into account to avoid exhausting one of the most important breeding sites for this Mediterranean endemic species

Little recovery of burrowing petrels after cat eradication

Cerfonteyn, M., & Ryan, P. G. 2016. Have burrowing petrels recovered on Marion Island two decades after cats were eradicated? Evidence from sub-Antarctic skua prey remains. Antarctic Science, 1-7.

In the 1980s, penguins dominated the prey remains of sub-Antarctic skuas Stercorarius antarcticus breeding on Marion Island, whereas on neighbouring Prince Edward Island burrowing petrels made up >95% of prey remains in nest middens. This difference resulted at least in part from the impact of introduced cats Felis catus on Marion Island’s burrowing petrel populations. Cats were introduced to Marion Island in 1949, and prior to their eradication in 1991, they killed an estimated 450 000 petrels each year, greatly reducing the densities of petrels breeding on the island. A repeat survey of skua prey remains showed that penguins still dominated the prey of breeding sub-Antarctic skuas on Marion Island in the summer of 2010–11, two decades after cats were eradicated from the island. The proportion of penguin remains decreased slightly compared to 1987–88, but this might be expected given the decreases in penguin numbers on Marion Island over this period. Regurgitated pellets confirmed the dominance of penguin prey on Marion Island. Taken together with the decrease in skua numbers on Marion Island over the last two decades, our results suggest that there has been little recovery in the population of at least summer-breeding burrowing petrels since cats were eradicated.

Feral cat predation on seabirds on Japanese islands

KAWAKAMI, K., & FUJITA, M. (2004). Feral cat predation on seabirds on Hahajima, the Bonin Islands, southern Japan. Ornithological Science, 3(2), 155-158.



The feral cats in the Bonin Islands are the cause ofgreat concern in relation to the conservation of native birds. Among the species found dead during this study, Tristram’s Storm-Petrel is listed as‘Vulnerable’ in the Japanese Red Data Book, so it isespecially urgent to take measures to conserve them. Many other threatened seabirds such as Matsudaira’s Storm-Petrel O. matsudairae and Audubon’s Shearwater P.lherminieri bannermani also breed in the Bonin Islands and they sometimes accidentally land on the ground in bad weather making them vulnerable to cat attacks. Thus, it is necessary to clarify the extent of feral cat predation in the islands and to control the cat population.

Different cat diet between islands

Bonnaud, E., Palmas, P., Bourgeois, K., Ollier, S., Zarzoso-Lacoste, D., & Vidal, E. (2015). Island specificities matter: cat diet differs significantly between islands of a major breeding archipelago for a vulnerable endemic seabird. Biological Invasions, 1-15.

Domestic cats are one of the most widespread predators on islands worldwide and are responsible for numerous reductions and extinctions of species on islands. The three main islands of the Hyères Archipelago house one of the largest colonies of the Mediterranean endemic Yelkouan shearwater Puffinus yelkouan that has recently been up-listed by the IUCN to ‘vulnerable’. The main objectives of this study were to assess the diet of cats and to study the effect of cat predation on Yelkouan shearwater populations at the archipelago scale. The diet of cats was studied using scat analyses according to years and seasons for each island. Simultaneously, Yelkouan shearwater breeding success was monitored during a period of 8 years on Port-Cros and Porquerolles, and 3 years on Le Levant. Descriptive analyses and GLM were used to compare data gathered on each island. At the archipelago scale, cats preyed strongly upon introduced mammals and shearwaters. Surprisingly, large differences appeared in cats’ diet according to the island considered. The Yelkouan shearwater was the primary prey of cats on Le Levant, but secondary on Port-Cros and Porquerolles. Cat predation was mainly concentrated during the shearwater prospecting period, when birds arrive at the colonies and look for a mate (if they are not already paired) and a burrow before breeding. Consequently cat impact was low on shearwater breeding success. However, this study demonstrates that the cat management conducted on Port-Cros was positive for fledging success. The successful cat eradication on Port-Cros supports the need to continue working for Yelkouan shearwater conservation with Le Levant as a priority, because this is where the colonies are largest and predation on Yelkouan shearwaters is very high.

Long-term protection of seabird breeding colonies on Tasman Island through eradication of cats

Robinson, S., Gadd, L., Johnston, M., & Pauza, M. (2015). Long-term protection of important seabird breeding colonies on Tasman Island through eradication of cats. New Zealand Journal of Ecology, 39(2), 0-0.

A restoration programme was initiated in 2008 in response to high levels of seabird predation by feral cats (Felis catus) at Australia’s largest fairy prion (Pachyptila turtur) colony on Tasman Island, Tasmania. The primary knockdown involved aerial baiting with para-aminopropiophenone (PAPP) in meat baits. The efficacy of baiting was lower than expected resulting in trapping and hunting commencing earlier than planned. Cats were successfully eradicated over two weeks. Key to the success of the programme was the identification of a narrow window of low prey availability for cats. Post-eradication monitoring of the two most common seabird species, fairy prions and short-tailed shearwaters (Ardenna tenuirostris), showed positive signs towards population recovery. Prion activity increased three-fold and shearwater breeding success increased.

A Feral Cat hunting for a Streaked Shearwater chick

SHIOZAKI,Tatsuya,  Masaki SHIRAI, Masato OSUGI, Maki YAMAMOTO, and Ken YODA. 2014. Predation by Feral Cat on Streaked Shearwater chicks on Awashima. Jpn J Ornithol 63(1) 2014, doi:10.3838/jjo.63.1

Feral cat attacks an endangered Hawaiian Petrel

Video provided by the Kauai Endangered Seabird Recovery Project shows a feral cat eating an endangered Hawaiian Petrel.

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.

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.

Cat predation on Zino's petrel

Zino, F. (1992). Cat amongst the freiras. Oryx, 26(03), 174-174.

A further threat to Pterodroma madeira was identified in 1991 when feral cats killed 10 petrels on a single ledge

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.

Feral Cats in the Ogasawara Islands

from http://www.japanprobe.com

Last week, the Ogasawara Islands were named a UNESCO World Natural Heritage site:

The island chain, which has never been connected with a continent, has been dubbed the “Galapagos of the Orient” because animals and plants there have undergone unique evolutionary processes–similar to wildlife on the Galapagos Islands.

In particular, 100 of the 106 species of land snails found on the islands are indigenous.

The islands, which include Chichijima and Hahajima islands, are regarded as the only place in the world where geological features visible from the ground show how an archipelago is formed when oceanic plates bump against each other.

Conservation groups have been working hard to protect the islands’ unique ecosystem. One conservation project involves the capture of feral cats, descendants of pets that humans brought to the island

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Increase in seabirds and changes in soil nutrients after removal of feral predators and alien plants

VanderWerf, E. A., Young, L. C., Crow, S. E., Opie, E., Yamazaki, H., Miller, C. J., Anderson, D.G., Brown, L.S., Smith D.G. & Eijzenga, J. (2014). Increase in Wedge‐tailed Shearwaters and Changes in Soil Nutrients following Removal of Alien Mammalian Predators and Nitrogen‐fixing Plants at Kaena Point, Hawaii. Restoration Ecology.

A predator-proof fence was built at Kaena Point Natural Area Reserve, Hawaii in 2010 as part of an ecosystem restoration project. All non-native mammalian predators were removed and are now excluded. Non-native plants are being removed and native species are being outplanted. We monitored abundance and reproduction of Puffinus pacificus (wedge-tailed shearwaters), collected soil samples before and after fence construction, and examined the relationship between changes in shearwater numbers and soil nutrients. Shearwater numbers increased over time, from 11 young produced in 1994 to 3,274 in 2012. The average number of shearwaters produced during the 3 years before and after fence construction increased from 614 ± 249 to 2,359 ± 802 (384% increase). The average number of shearwater pairs attempting to nest also increased during the same periods, from 3,265 ± 827 to 4,726 ± 826 (45% increase). Soil samples from 2010 to 2013 showed an overall decline in concentration of ammonium (NH₄⁺) and no change in concentration of nitrate (NO₃⁻) or orthophosphate (PO₄³⁻). . However, there was a positive relationship between changes in shearwater numbers and changes in ammonium. Examination of spatial patterns in nutrient abundance showed that the highest nutrient concentrations occurred in areas dominated by the non-native nitrogen-fixing plants Leucaena leucocephala and Prosopis pallida. Removal of these plants caused local nutrient declines, but increases in shearwater numbers have countered this at some points. We anticipate that shearwaters and other seabirds will replace non-native plants as the dominant source of nitrogen and phosphorous and facilitate recovery of a native-dominated plant assemblage.

Feral cat eradication from Pacific atolls

Rauzon, M. J., Everett, W. T., Boyle, D., Bell, L., & Gilardi, J. (2008).Eradication of feral cats at Wake Atoll. National Museum of Natural History, Smithsonian Institution.

Feral cats (Felis catus) were introduced at Wake Atoll, (19°18' N, 166° 38' E) in the 1960s as pets and probably to control rats on this U.S. military base in the North Pacific Ocean. After base-downsizing in the 1970s, feral cats became a noticeable problem. Hunting and trapping to control their numbers has been sporadic over time but began seriously in 1996 and continued through 2002, during which time about 200 cats were removed. The eradication effort began in July 2003 and by January 2004 another 170 cats had been removed. During visits from late 2004 to 2007, two feral cats were seen but no cat reproduction was detected.

Bird populations responded quickly to the release of predation: Masked Boobies (Sula dactylatra) increased from three breeding pairs in 1996 to 25 by 2007; the Brown Booby (S. leucogaster) population rose from 73 nests in 1996 to 162 in 2003. Wedgetailed Shearwaters (Puffinus pacificus) recolonized around 1998 and populations expanded to form at least three colonies with individuals in numerous locations around the atoll. Gray-backed Terns (Onychoprion lunata), not recorded breeding on the atoll since the 1980s, began nesting in two new sites, and Great Frigatebirds (Fregata minor), which had not been recorded nesting since the 1960s, renewed reproductive efforts in 2005. Due to feral cat removal and wet weather, Pacific Rats (R. exulans) greatly increased. Current rodent control effort was less effective than it should be because hermit crabs (Coenobita perlata) ate the bait before the rats did. A bait station model design to exclude crabs was designed and tested. The island managers continued to control rats at Wake around housing areas, and rodent populations have declined since their peak following cat eradication.

On Aug. 31, 2006, Wake Island was struck by Super Typhoon Ioke. Winds over 130 mph knots broke many trees and damaged the island infrastructure but the island was soon functioning again. In June 2007, we returned and found a few cats survived. They appear to be the same cats known to remain at the end of our eradication, are likely the same sex since no kittens have been detected since then.

Can cat predation help competitors coexist in seabird communities?

Pontier, D., Fouchet, D., & Bried, J. (2010). Can cat predation help competitors coexist in seabird communities?. Journal of theoretical biology, 262(1), 90-96.

On oceanic islands, nest site availability can be an important factor regulating seabird population dynamics. The potential for birds to secure a nest to reproduce can be an important component of their life histories. The dates at which different seabird species arrive at colonies to breed will have important consequences for their relative chances of success. Early arrival on the island allows birds to obtain nests more easily and have higher reproductive success. However, the presence of an introduced predator may reverse this situation. For instance, in the sub-Antarctic Kerguelen archipelago, early arriving birds suffer heavy predation from introduced cats. Cats progressively switch from seabirds to rabbits, since the local rabbit population starts to peak after early arriving seabird species have already returned to the colony. When late-arriving birds arrive, cat predation pressure on seabirds is thus weaker. In this paper, we investigate the assumption that the advantage of early nest monopolization conferred to early arriving birds may be counterbalanced by the cost resulting from predation. We develop a mathematical model representing a simplified situation in which two insular seabird species differ only in their arrival date at the colony site and compete for nesting sites. We conclude that predation may ensure the coexistence of the two bird species or favor the late-arriving species, but only when seasonal variations in predation pressure are large. Interestingly, we conclude that arriving early is only favorable until a given level where high reproductive success no longer compensates for the long exposure to strong predation pressure. Our work suggests that predation can help to maintain the balance between species of different phenologies.

Reducing feral cat threats to native wildlife in Hawai`i

Hess, S. C., H. Hansen, and P. C. Banko. 2007. Reducing feral cat threats to native wildlife in Hawai`i. Hawai`i Cooperative Studies Unit Technical Report HCSU-010. University of Hawai`i at Hilo. 102 pp., incl. 14 figures, & 19 tables.

We documented the diet of feral cats (Felis catus) on Kīlauea and Mauna Loa within Hawai`i Volcanoes National Park (HAVO), determined the incidence of three feline diseases on Mauna Kea, studied feral cat home range, developed and tested trap-signaling devices, tested food-based baits and attractants, analyzed feral cat population dynamics using genetic techniques, and developed an adaptive strategy for reducing predation on endangered Hawaiian birds.

We documented the diet of feral cats by analyzing the contents of 42 digestive tracts from Kīlauea 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 Kīlauea and Mauna Loa. On Mauna Loa, significantly more (89%) feral cats consumed small mammals, primarily rodents, than on Kīlauea 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 Kīlauea. 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.

We determined prevalence to feline immunodeficiency virus (FIV) antibodies, feline leukemia virus (FeLV) antigen, and Toxoplasma gondii antibodies in feral cats on Mauna Kea Hawai`i from April 2002 to May 2004. Six of 68 (8.8%) and 11/68 (16.2%) were antibody positive to FIV and antigen positive for FeLV, respectively; 25/67 (37.3%) were seropositive to T. gondii. Antibodies to FeLV and T. gondii occurred in all age and sex classes, but FIV occurred only in adult males. Evidence of previous or current infections with two of these infectious agents was detected in eight of 64 cats (12.5%). Despite exposure to these infectious agents, feral cats remain abundant throughout the Hawaiian Islands.

Feral cats in dry subalpine woodland of Mauna Kea, Hawai`i, live in low density and exhibit some of the largest reported home ranges in the literature. While 95% fixed kernel home range estimates for three females averaged 772 ha, four males averaged 1,418 ha, and one male maintained a home range of 2,050 ha. Mean daily movement rates between sexes overlapped widely and did not differ significantly (P = 0.083). Log-transformed 95% kernel home ranges for males were significantly larger than those of females (P = 0.024), but 25% kernel home ranges for females were larger than those of males (P = 0.017). Moreover, logtransformed home ranges of males were also significantly larger than those of females in this and seven other studies from the Pacific region (P = 0.044). Feral cats present a major threat to endangered Hawaiian birds, but knowledge of their ecology can be used for management by optimizing trap spacing and creating buffer zones around conservation areas.

Frequent checks of live traps require enormous amounts of labor and add human scents associated with repeated monitoring which may reduce capture efficiency. To reduce efforts and increase efficiency, we developed a trap-signaling device with long-distance reception, durability in adverse weather, and ease of transport, deployment, and use. Modifications from previous designs include a normally-open magnetic switch and a mounting configuration to maximize reception. The system weighed < 225 g, was effective ≤ 17.1 km, and failed in < 1% of trap-nights. Employing this system, researchers and wildlife managers may reduce the amount of effort checking traps while improving the welfare of trapped animals.

Successful feral cat control programs require effective baits and lures. Non-targets may interfere with trapping efforts by rapidly consuming bait before feral cats encounter traps, necessitating frequent bait replacement. We compared the effectiveness of baits and lures by analyzing capture rates of feral cats and non-targets and monitoring animal visits to bait stations with remotely-triggered cameras. We tested four different baits and attractants: canned cat food, sardines, catnip, and a bait sausage that we formulated from pork and fat. We trapped for a total of 3,389 trap nights and captured 35 feral cats. There were 323 incidences of trap interferences, reducing the effective trap nights (ETN) to 3,225. The primary cause of trap interference was feral pigs rolling over traps (n = 185, 57.3% of interferences). The primary non-target species captured were small Indian mongooses (n = 74, 22.9% of interferences). Overall, more cats and mongooses were captured using sardines, although the catch frequencies were not dependent on the bait type used. We obtained photographs of 1,476 small mammals at the bait stations. Mongooses were the principal mammals photographed (n = 939, 69.5% of pictures). We also obtained 398 photographs of rats (29.5%) and 9 (0.7%) of mice. Feral cats were photographed only 5 (0.4%) times. We found strong differences between mongooses, rodents, and cats photographed at the four bait types. Sardines were the most visited bait type (n = 641, 47.4% of photographs). Pork sausage and cat food accounted for 383 (28.3%) and 322 (23.8%) visits while catnip had only 67 (5.0%) visits. Feral cats were photographed only at sardine bait. Mongooses were attracted primarily to  sardines (49.3%). Pork sausage was the most attractive bait to rats, accounting for 44.5% of photographs. Due to the high rate of non-target interference, other attractants need to be tested for successful feral cat control programs.

Population genetics can provide information about the demographics and dynamics of invasive species that is beneficial for developing effective control strategies. We studied the population genetics of feral cats on Hawai`i Island by microsatellite analysis to evaluate genetic diversity and population structure, assess gene flow and connectivity among three populations, identify potential source populations, characterize population dynamics, and evaluate sex-biased dispersal. High genetic diversity, low structure, and high number of migrants per generation supported high gene flow that was not limited spatially. Migration rates revealed that most migration occurred out of West Mauna Kea. Effective population size estimates indicated increasing cat populations despite control efforts. Despite high gene flow, relatedness estimates declined significantly with increased geographic distance and Bayesian assignment tests revealed the presence of three population clusters. Genetic structure and relatedness estimates indicated male-biased dispersal. Mauna Kea may be a source population that can be targeted for control. However, recolonization seems likely given the great dispersal ability that may not be inhibited by barriers such as lava flows. Genetic monitoring will be necessary to assess the effectiveness of future control efforts.

Despite the long history of feral cats in Hawai`i, there has been little research to provide strategies to improve control programs and reduce depredation on endangered species. Our objective was to develop a predictive model to determine how landscape features on Mauna Kea such as habitat, elevation, and proximity to roads affect the number of feral cats captured at each trap. We used log-link generalized linear models and QAICc model ranking criteria to determine the effect of these factors. We found that the number of cats captured per trap was related to trapping effort, habitat type, and whether traps were located on the West or North Slope of Mauna Kea. We recommend an adaptive management strategy to minimize trapping interference by non-target small Indian mongoose (Herpestes auropunctatus) with toxicants, to focus trapping efforts in māmane (Sophora chrysophylla) habitat on the West slope of Mauna Kea, and to cluster traps near others that have previously captured multiple cats.

Myths and facts about “managed” cat colonies

Winter, L. (undated). Myths and facts about “managed” cat colonies. ABC

1. Cat colonies don't just die out in one or two years: Although promoters of Trap/Neuter/Release (TNR) often claim that the colonies die out through attrition in just a few years, there is very little evidence to support this claim. Even the Adams Morgan cat colony of only 30 original cats in the District of Columbia, which was "managed" by the founders of Alley Cat Allies, took 10 years to die out. It is often difficult to trap all of the cats, the cat food that is left out attracts more cats, and cat colonies often become dumping grounds for unwanted pets (Donald, R.L. 1992. Should Feral Cats Be Euthanized? Shelter Sense: 3-7). Volunteers can become overwhelmed and may not have all of the financial resources or the manpower needed to trap and alter every cat in a colony (Passamsi, w.c., D.W. Macdonald. 1990. The Fate of Controlled Feral Cat Colonies. Universities Federation for Animal Welfare, Hertfordshire, England. 48).
Please note the following: "It's just so overwhelming. I'm in over my head. I can't even afford to eat or buy clothes or do anything. I wake up in the morning hoping I can make it through the day." (Puzzanghera, J. 1995. So Many Cats, So Little Time, San Jose Mercury News, July 19, 1995.)

2. TNR is not meant to eliminate colonies of cats: The purpose of TNR is NOT to eliminate cat colonies, but to perpetuate them because cat feeders believe that if a neutered colony is removed, an intact colony will move in and take it's place.
Please see the following: "You will never get rid of the cats in that area, and it is not advisable to do that. Because if you're doing a neutering to eradicate the cats by neutering, and remove them completely from the area, you are just being the same as somebody who wishes to go and trap them out and kin them. All you're doing is delaying the day Of death." (From a presentation by Roger Tabor, Alley Cat Allies Seminar, "Focus on Ferals," July 8, 1994, Washington, DC.)
More cats may move into an area ONLY if the food source remains. If cats are trapped out and the food source is removed, a cat colony will not reform in that location. This is exactly what occurred at Riverside National Park where over 25 cats were being fed daily. Over the strong objections of the cat feeders and Alley Cat Allies, and in the face of a negative media campaign, the National Park Service removed the cats, the feeding was stopped, and no additional cats have congregated in the area. The Cats were not euthanized, but taken to a local Shelter (Sealy, D. 1996. Removal of a Colony of Free-Ranging Cats From an Area Administered by the National Park Service: A Case History, in: Proceedings of the 1995 International Wildlife Rehabilitation Council Conference, Virginia Beach, VA. Pp 75-77).

3. Cat colonies attract other predators: The cat food left out attracts raccoon, skunk, opossum, fox, coyote, and rats, all predators of birds and carriers of diseases that can be transmitted to other cats, wildlife, or humans, such as rabies. No one is neutering and giving rabies vaccinations to these animals to control their populations and the spread of disease. I have personally witnessed a huge rat hole right under a cat feeding station, and studies have shown that cats do not do a very good job of Controlling rat populations (Childs, J. E. 1991. And the Cat Shall Lie Down With the Rat, Natural History: 16 - 19).
I also have slides of raccoons at cat feeding stations, and e-mail messages from cat feeders discussing the problem of raccoon and opposum at their stations.

4. The cats are not always tested or vaccinated for fatal feline diseases: Some groups, such as the Feral Cat Coalition (http://www.feralcat.com/tpolicy.html), do not follow the American Veterinary Medical Association's guidelines which state that cats in a "managed" cat colony should be tested and vaccinated for infectious diseases and adopted or euthanized if positive. Thus, diseased cats in "managed" cat colonies could come in contact with and infect free-roaming pet cats. Cats with fatal feline diseases will suffer and die a miserable death, calling into question the very humaneness of this practice.

5. Domestic cats are not strictly territorial: Cat feeders will often say that altered cats defend their territory, and do not let other cats join the colony. There is scant scientific evidence to support this claim either. It is well-known that the home ranges of domestic cats overlap. In fact, Dr. Carol Haspel, who conducted a number of studies of cat colonies in Brooklyn, NY, says that cats occupying a certain area "absolutely do not" keep others out, "particularly if there is a feeder." (Donald, R.L. 1992. Should Feral Cats Be Euthanized? Shelter Sense: 3-7).

6. Well-fed, altered cats still kill birds and can impact wildlife populations: It has been extensively documented that domestic cats can severely impact seabird populations on islands (Moors, P.J. and I.A.E. Atkinson. 1984. Predation on seabirds by introduced animals, and factors affecting its severity. ICBP Technical Publication 2:667-690), and well-fed Cats still kill wildlife (Adamec, R.E. 1976. The interaction of hunger and preying in the domestic cat (Felis catus): an adaptive hierarchy? Behavioral Biology 18: 263-272.)
Cats and other predators can also have an impact on songbird populations in fragmented and isolated habitat (Wilcove, D.S. 1985. Nest predation in forest tracts and the decline of migratory songbirds. Ecology 66: 1211- 1214.)

Please see the following quote regarding a scientific study conducted in two California parks-one with over 20 cats that were fed daily, and one without cats:
Cats at artificially high densities, sustained by supplemental feeding, reduced the abundance of 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. (Hawkins, C.C., W.E. Grant, М.Т. Longnecker. 1999. Effect of Subsidized House Cats on California Birds and Rodents. 1999 Transactions of the Western Section of The Wildlife Society 35: 29-33.)