A widespread search in 2015, using automatic cameras, yielded only a rare glimpse of a single individual. A long time has passed without conclusive evidence of the cat’s survival, and sadly this domestic species must be considered ‘probably extinct’ on Christmas Island. The personal opinion of the authors, however, based mainly on the continued and increasing incidence of impressive sightings and the availability of apparently suitable prey, is that there is still a chance that this intriguing animal has survived to the present day.

Q. Yong, G. Chia, 'Search for the Last Christmas Island Cat', 2015

Any contemplation of cat control or eradication on Christmas Island would need to be tempered by the knowledge that this would probably lead to an increase in the numbers of R. rattus, a species that itself can be a serious predator, particularly of ground-nesting birds, that has caused declines or extinctions on many islands (Atkinson 1985). Conversely, removal of rats would probably cause the cats to turn more to other prey. Thus an integrated pest control programme for the two species would be absolutely mandatory (see Newsome 1990). Because of this interaction between the two introduced species, Christmas Island may well be a case of an oceanic island where feral cats are beneficial to the management of native species.
Tidemann, C.R., H.D. Yorkston, A.J. Russock, ‘The diet of Cats, Felis catus, on Christmas Island, Indian Ocean’, Wildlife Research 21, 1994