Proposed management plan for cats and black rats on Christmas Island.

Algar, D., & Johnston, M. (2010). Proposed management plan for cats and black rats on Christmas Island. Government of Western Australia Department of Environment and Conservation.

Proposed management plan for cats and black rats on Christmas Island 1Report outline The impact of cats on the biodiversity of Christmas Island is of concern to land management agencies and the broader  community.  Domestic  and  stray  cats  reside  in  the  residential,  commercial  and  light industrial  area while a population of feral cats exists across the rest of the island (i.e. mining lease, national park and other  Crown  land).  Concern  has  been  raised  regarding  the  threat  that  all ‘classes’  of  cats  present  to  the  viability  of  a  number  of  endangered  fauna  populations. Additionally,  previous  research  has  demonstrated  that  the  cats  on  the  island  also  have  a  very high  prevalence  of  Toxoplasmosis, a  parasite  that  can  lead  to  serious  human  health complications.The  management  of  cats  on  the  island  is  a  complex  task  as reduction/eradication in cat numbers alone could lead to changes in the abundance of other exotic species populations, especially  the  introduced  black  rat  which  then  may  threaten  wildlife  species  and  also  have disease implications.  

Land  management  agencies  on  Christmas  Island  have  commissioned  this report  which  describes  the  rationale and development of a long-term cat and black rat management and eradication plan to mitigate the environmental  and  social  impacts  of  cats  and  black  rats across  all  land  tenures  (shire-managed  lands,  Crown land including mine leases and Christmas Island National Park).   

The  report  provides  a  background  to  the  threats  and  impacts  of  cats and  black  rats  on  the  island’s  natural  and  social  environment,  including  wildlife  predation  and disease  threats  to  wildlife  and  human  health.  It  documents  previous  reports  in  relation  to impact  and  management  of  cats  and  black  rats  on  Christmas  Island.  The  current  local  cat management  laws  (Shire  of  Christmas  Island  Local  Law  for  the  Keeping  and  Control of Cats 2004) under the Local Government Act 1995 (WA) (CI) are evaluated (see Appendix 1) with the aim of limiting domestic and stray cat impact on the iconic native fauna of Christmas Island, promoting responsible cat ownership, compliance and enforcement of cat management laws and measures required to implement a ‘last cat policy’ for the Island.  

Cat  and  rodent  eradication  programs  and strategies  developed  and/or  implemented  by other conservation  agencies and local governments, particularly for islands are evaluated for their utility on Christmas Island. A strategy  is recommended that  provides  a staged approach  to  cat  and black  rat  management and  control  leading to eradication of one or both target species. Techniques, actions and priorities are described as are recommendations   of   where   additional   research   is   required.   A   monitoring   program   to   measure   the   effectiveness  of  the  strategy  is  reported which  enables  investigation  of  the potential  relationships  between  cats  and  their  invasive species  prey,  including  rodents  and centipedes,  and  strategies  to  address  any  negative environmental or social impacts of cat control. Monitoring requirements to maintain a cat and black rat free status including quarantine requirements to prevent, detect and quickly manage, new incursions are also discussed. 

Timelines and resource requirements to undertake this program are provided in Appendix 2. 

The eradication of alien mammals from five offshore islands, Mauritius

Bell, B. D. (2002). The eradication of alien mammals from five offshore islands, Mauritius, Indian Ocean. In Veitch, C. R., & Clout, M. N. (2002). Turning the Tide: The Eradication of Invasive Species: Proceedings of the International Conference on Eradication of Island Invasives,[University of Auckland, 19 to 23 February 2001] (No. 27). IUCN 40-45.

Following the removal of rabbits from Round Island in 1979 and the publication of a management plan in 1989, the Mauritius Government contracted Wildlife Management International Limited in 1993 to fulfil one of the plan’s recommendations to survey the offshore islands of Mauritius and Rodrigues and to prepare an offshore islands management plan. This plan made a number of recommendations and priorities in relation to the removal of alien species. In 1995 work on the priorities began with the removal of Norway rats (Rattus norvegicus) and hares (Lepus nigricollis) from Gunner’s Quoin, ship rats (R. rattus) from Gabriel Island and mice (Mus musculus) from Ile Cocos and Ile aux Sables. In 1998 cats (Felis catus), ship rats and mice were removed from Flat Island and rabbits (Oryctolagus sp.), which had been illegally released following the earlier eradications, from Gunner’s Quoin. These programmes were hand-laid operations. In all cases the main bait was grain-based pellets containing 0.02gm/kg brodifacoum. The bait was set out on at least half of the maximum grid recommended for the rodent species targeted. The exception was cats, which were trapped in leg-hold traps. Plans are being considered for the re-introduction of reptiles and birds. Some planting of native trees has begun. This paper covers the eradication sector of the management plan

Cats on Dassen Island

Apps, P. 1984. Cats on Dassen Island. Acta Zool. Fennica, 172: 115-116.

Dassen Island, a small island off the west coast of South Africa, is an important nesting site for sea birds. Introduced mammals include Felis catus and Oryctolagus cuniculus. Studies on the ecological impact of the feral cat population showed that birds and rabbits contributed almost equally to the diet of the cats, but that most of the birds were scavenged, so that the impact of cat predation on their populations was insignificant, while rabbits were hunted and the effect may have been ecologically important. The cats' ecological role was influenced strongly by their behaviour, which must be considered in the planning of conservation or control measures.

Introduced mammals impacts on seabirds in Îles Éparses

Russell, J. C., & Le Corre, M. (2009). Introduced mammal impacts on seabirds in the Îles Éparses, Western Indian Ocean. Marine Ornithology, 37, 121-128.

Invasive mammals have devastated endemic island communities throughout the world, and seabirds have proven particularly vulnerable, with many species extinctions. Introduced predators have had the greatest effect through direct predation, but this effect can now be mitigated by modern eradication techniques. However, the removal of a species from a community can generate different indirect effects depending on the trophic levels that are interacting. Conservation managers eradicating introduced mammals must consider ecosystemwide effects and view island management within a “whole ecosystem” context. It is important to consider unexpected indirect effects from eradications. However, eradication of introduced mammals should not be delayed, especially when direct effects such as predation are a known cause of terminal decline for a threatened species. We use the French Îles Éparses of the Western Indian Ocean, with their various combinations of six introduced mammals, to demonstrate the direct and indirect effects that introduced mammals may have, and how those effects might affect the regionally important seabirds with breeding colonies on the islands. We conclude by making recommendations for the future management of the islands.

Eradication of alien predators in the Seychelles

Shah, N. (2001). Eradication of alien predators in the Seychelles: an example of conservation action on tropical islands. Biodiversity and Conservation, 10(7), 1219-1220.
(No summary available)

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.

Diet of cats and impact on seabirds at Juan de Nova Island

Peck, D. R., Faulquier, L., Pinet, P., Jaquemet, S., & Le Corre, M. (2008). Feral cat diet and impact on sooty terns at Juan de Nova Island, Mozambique Channel. Animal Conservation, 11(1), 65-74.
Feral cat Felis catus predation on seabirds has been well documented; however, details regarding shifts in feral cat diet in relation to seabird availability, seabird predation rate and impact on seabird population dynamics are scarce. Here, we present data documenting a seasonal shift in feral cat diet at Juan de Nova Island, Mozambique Channel. We also quantify sooty tern Sterna fuscata predation by feral cats and examine the impact on sooty terns over both the short term (by removing individual cats from sub-colonies) and over the longer term by highlighting their influence on population growth rate (l) using a deterministic matrix model. Cat diet shifted dramatically from insects, rats and mice outside the tern breeding season to primarily terns when terns were breeding. The predation rate of sooty terns at Juan de Nova was estimated at 5.94 terns/cat /day , with a proportion of these (22%) being killed without being consumed (‘surplus kills’). When only one cat was removed from each sub-colony, tern predation declined tenfold in the short term. From our matrix model, the annual growth rate for sooty terns was 1.01 in the absence of cat predation. It remained above one until a predation impact equivalent to approximately three times the estimated cat density (12.04 per km²  was incorporated. Our results demonstrate that cats preferentially predate and have an impact on breeding sooty terns at Juan de Nova, and that an increase in cat density could lead to negative effects on population growth, despite the large breeding tern population

Eradication of feral cats leads to partial Seychelles magpie robin population recovery

Watson J., Warman C., Todd D. & Laboudallon V. (1992) The Seychelles magpie robin Copsychus sechellarum: ecology and conservation of an endangered species. Biological Conservation, 61, 93-106.

In 1977–1978 some 40 Seychelles magpie robins Copsychus sechellarum, the entire world population, survived on Frégate island. These lived in 12 territorial groups of up to six individuals. Their range on Frégate was limited by the amount of feeding habitat, specifically bare earth and leaf litter which occurred under mature shady woodland and in cultivated vegetable gardens. Two attempts were made to reintroduce the species to Aride Island in 1978 and 1979. These were unsuccessful and the translocations had to be abandoned when a new threat impinged on the parent population of Frégate in 1980.
By 1981 numbers there had declined to 18, with virtually no recruitment, and an increase in the feral cat population was implicated. A successful cat eradication programme by trapping and poisoning was carried out in 1981–1982. By 1983–1984 the population showed a recovery with recruitment again healthy, although the abandonment of agriculture on Frégate between 1979 and 1983 had caused a reduction in the amount of feeding habitat and in the carrying capacity of the island to around 25 individuals in eight territorial groups. A range of management options is discussed.

See also here.

Diet of feral cats on Christmas Island

Tidemann, C.R., Yorkston, H.D. & Russack, A.J. 1994. The diet of cats, Felis catus, on Christmas Island, Indian Ocean. Wildlife Research. 21 (3): 279-285.

Cats, Felis catus, were taken to Christmas Island (10°25'S,105°40'E) in the Indian Ocean at the time of first settlement in 1888 and a feral population became established soon thereafter. In 1988 a wide range of vertebrate and invertebrate animals was present in the diet of these feral cats, but flying-foxes, Pteropus melanotus, fruit pigeons, Ducula whartoni, and introduced rats, Rattus rattus, together constituted 80% of their food intake by weight. Of the guts examined, 45% contained R. rattus, and this species accounted for 31% of food intake by weight. Less than 10% of cat guts contained P. melanotus and D. whartoni, but the large body weights of these species meant that by weight they made up 21% and 28% respectively. Mus musculus was found in 27% of guts examined, although it contributed only 2% by weight. It is likely that the large numbers of feral cats present in vegetative regrowth on mined areas are related to the ease with which all four primary prey species may be caught there. No evidence was found that cats are having a deleterious effect on native species and they may well be beneficial in stabilising the numbers of R. rattus, which itself can be a serious predator of nesting birds.

Cat predation on turtle hatchlings

Seabrook, W. 1989. Feral cats (Felis catus) as predators of hatchling green turtles (Chelonia mydas). J. Zool., Lond., 219: 83-88

In many parts of the world feral animals have been reported to have severe effects on marine turtle hatchling production. In this study, green turtle (Chelonia mydas) hatchlings were shown to be an important component of the diet of the feral cat (Felis catus) on Aldabra Atoll, Seychelles, and feral cat activity in the coastal areas was found to be concentrated on the beaches used most intensively by turtles for nesting. The impact of the feral cat's predation on green turtle recruitment could not be determined. However, despite cat predation, the size of the Aldabran green turtle nesting population has increased considerably since human exploitation ceased.

Transmision modes for FPLV

Berthier, K., M. Langlais, P. Auger, & D. Pontier. 2000. Dynamics of a feline virus with two transmission modes within exponentially growing host populations. Proceedings of the Royal Society, Biological Sciences, 267(1457): 2049–2056.

Feline panleucopenia virus (FPLV) was introduced in 1977 on Marion Island (in the southern Indian Ocean) with the aim of eradicating the cat population and provoked a huge decrease in the host population within six years. The virus can be transmitted either directly through contacts between infected and healthy cats or indirectly between a healthy cat and the contaminated environment: a specific feature of the virus is its high rate of survival outside the host. In this paper, a model was designed in order to take these two modes of transmission into account. The results showed that a mass-action incidence assumption was more appropriate than a proportionate mixing one in describing the dynamics of direct transmission. Under certain conditions the virus was able to control the host population at a low density. The indirect transmission acted as a reservoir supplying the host population with a low but sufficient density of infected individuals which allowed the virus to persist. The dynamics of the infection were more affected by the demographic parameters of the healthy hosts than by the epidemiological ones. Thus, demographic parameters should be precisely measured in field studies in order to obtain accurate predictions. The predicted results of our model were in good agreement with observations.

Cat eradication on Marion island

Bester, M.N., Bloomer, J.P., van Aarde, R.J., Erasmus B.H., van Rensberg P.J.J., Skinner J.D., Howell P.G. & Naude T.W. 2002. A review of the successful eradication of feral cats from sub-Antarctic Marion Island, Southern Indian Ocean. South African Journal of Wildlife Research, 32, 65-73.

This paper reviews the history of the feral cat eradication programme on sub-Antarctic Marion Island based on unpublished minutes of meetings, reports, letters, theses and published scientific papers; and reflects on the outcome of the eradication campaign. The 19-year programme comprised seven phases, commencing with a description of the effect of the cats on the Marion Island ecosystem, the characteristics of the cat population and the formulation of a management policy (phase 1: 1974–1976). Methods for control were selected and preparations were made for the implementation of the primary control measure, biological control with the feline panleucopaenia virus (phase 2: 1976/77). The virus was released in 1977 (phase 3: 1977), followed by the determination of its effects (phase 4: 1977–1980). Monitoring of the effects of the virus continued, and the secondary control measure of hunting at night was tested (phase 5: 1981–1983). Full-scale implementation of hunting and continued monitoring of the effects of both the disease and hunting followed (phase 6: 1986–1989). The inclusion of intensive trapping and poisoning as tertiary control measures culminated in the final eradication of cats from Marion Island in 1991 (phase 7: 1989–1993).

Lessons to be learnt from loss of the pipistrelle

A recent paper in the journal Conservation Letters alleges that failure to act quickly on evidence of rapid population decline has led to the first mammal extinction in Australia in the last 50 years, the Christmas Island pipistrelle bat (Pipistrellus murrayi).

Since 26 August 2009, there have been no recordings of the echolocation call of the tiny bat, which is native to Christmas Island. It is now presumed extinct.

In a recently published paper in Conservation Letters, scientists analysed the conservation decision making process associated with the decline of this species and concluded that it illustrated the need for strong leadership on extinction issues.

Among the chain of events analysed was a February 2009 report by Dr Lindy Lumsden – Principal Research Scientist with the Arthur Rylah Institute for Environmental Research, and foremost authority on this species – warning that only 20 bats remained on Christmas Island. Government funding was then allocated to establish a captive breeding program, but that proved too little, too late.

The Christmas Island pipistrelle fed on insects and roosted in tree hollows and decaying vegetation. Just a few decades ago, the bat was widespread on Christmas Island and roosted in groups of 50 or so animals.

‘It is estimated that a single pipistrelle consumes its body weight in insects per night,’ lead author Tara Martin, of CSIRO’s Ecosystem Services, told the conservation website Mongabay.

‘While the loss of the pipistrelle is likely to lead to more insects, it is too early to tell what the long term ecological impact of this will be on the island.’

Scientists are unsure as to what pushed the bat to extinction. It is possible that a combination of stressors was responsible, including invasive animals such as feral cats, the common wolf snake, and a recent invasion of yellow crazy ants. Disease is another possibility, though researchers could find no sign of the bats suffering from illness...

http://www.ecosmagazine.com/paper/EC12309.htm

Martin, T. G., S. Nally, A.A. Burbidge, S. Arnall, S.T. Garnett, M.W. Hayward, L.F. Lumsden, P. Menkhorst, E. McDonald-Madden & H.P. Possingham. 2012. Acting fast helps avoid extinction.Conservation Letters, 5(4), 274-280.

Failure to act quickly on evidence of rapid population decline has led to the first mammal extinction in Australia in the last 50 years, the Christmas Island Pipistrelle (Pipistrellus murrayi). The fate of another iconic species, the migratory Orange-bellied Parrot (Neophema chrysogaster), monitored intensively for over 20 years, hangs in the balance. To inform future conservation management and decision making, we investigate the decision process that has led to the plight of both species. Our analysis suggests three globally relevant recommendations for minimizing species extinction worldwide: (1) informed, empowered, and responsive governance and leadership is essential; (2) processes that ensure institutional accountability must be in place, and; (3) decisions must be made whilst there is an opportunity to act. The bottom line is that, unless responsive and accountable institutional processes are in place, decisions will be delayed and extinction will occur.