Dibblers are semi-arboreal and mainly crepuscular. They once occupied a variety of habitats. Mainland occurrences of Dibblers have been characterised by the presence of long-unburnt heathland. This generalisation applies to records from Cheyne Beach, Torndirrup National Park and most records from Fitzgerald River National Park. Typically, captures have been on sandy substrates although occasional records are on laterite soils (Baczocha and Start 1996; Barrett 1998). Vegetation structure is the feature providing most similarity between capture sites and Baczocha and Start (1997) suggested that Dibblers ‘...seem to prefer vegetation with a dense canopy >1 metre high which has been unburnt for at least 10 years’. Dense vegetation may be preferred because it supplies abundant invertebrate prey, or it may provide protection from predation by foxes and cats, or both. In 1996, however, Dibblers were captured in an area that had been burnt seven years previously, but this was in an area that had been baited for foxes for several years (Friend 2004). Extensive fire has been a frequent occurrence in Fitzgerald River National Park over the few decades and the subpopulations within the Park are small and fragmented.

A study of the habitat preferences of island Dibblers (Bencini et al. 2001) found that on Boullanger Island there was no significant difference between trap success in low-closed heath, foredune heath, open scrubland and sword sedge Lepidosperma sp. thicket. On Whitlock Island, significantly greater capture rates were recorded in dunal scrubland and foredune heath than in succulent heath. On Boullanger and Whitlock Islands, a study has shown that diet consisted of c. 20% plant material with the remainder being invertebrates. Scat analysis showed that Dibblers consumed at least 10 orders of invertebrates ranging in length from 0.1 mm to 25 mm with an average size of 4.5 ± 0.4 mm. The Dibblers did not select for a particular size or taxon of prey, but fed on any invertebrates that were readily available to them. This suggests that Dibblers are essentially insectivorous dietary generalists and opportunists (Miller et al. 2003). Boullanger and Whitlock Islands have often-dense populations of the introduced House Mouse Mus musculus. Boullanger Islands has a subpopulation of Sminthopsis griseoventer (see conservation summary for the Boullanger Island Dunnart).

Concern that Mus was depressing Dibbler numbers led to their introduction to Escape Island (Moro 2003). A study of the feasibility of eradicating the mice has been carried out (Friend et al. 2009) and the Dibbler Recovery Team is overseeing a project aimed at carrying out the eradication (J. Friend pers. comm.). Mills et al. (2006) found that the Boullanger and Whitlock Island subpopulations had low levels of heterozygosity and high levels of inbreeding compared with mainland populations. The Whitlock Island Dibbler subpopulation appears to have been founded by animals from Boullanger Island, but founder effects and isolation have resulted in two genetically distinct subpopulations. There is evidence of some genetic exchange, but only as a rare event.

The Dibbler once occurred widely with subfossil records suggesting a range from Dirk Hartog Island (Shark Bay) and the Zuytdorp Cliffs north of Geraldton, near Jurien, to Peak Charles (130 km north east of Esperance) and east to the Eyre Peninsula, South Australia. Early specimens, all from Western Australia, came from Moore River (near today’s New Norcia), Wanneroo, near Kojonup, King George Sound (Albany) and ‘Salt River’ (Pallinup River, 100 km north east of Albany) (Ride 1970; Maxwell et al. 1996; Friend 2004).

Long thought extinct, the Dibbler was rediscovered at Cheyne Beach, east of Albany, in 1967 (Morcombe 1967). Since then specimens have come from Torndirrup National Park (Smith 1990), Arpenteur Nature Reserve (Cheyne Beach), Waychinicup National Park, near Jerdacuttup (Woolley 1977) and Fitzgerald River National Park (Muir 1985; Chapman and Newby 1995; Friend 2004; Sanders et al. 2012). Currently, the only known natural mainland subpopulations are in Fitzgerald River National Park. In 1985 it was discovered on Boullanger (31 ha) and Whitlock (5 ha) Islands in Jurien Bay (Fuller and Burbidge 1987); genetic differentiation between these two island populations indicates that there is little interchange between them (Mills et al. 2003) and they are regarded as separate subpopulations. Dibblers were introduced to Escape Island (11 ha), Jurien Bay, in 1998-2000 (Moro 2003), and reintroduced to Peniup Nature Reserve (2001) and Stirling Range National Park (2004) (Friend 2008). From 2010 there have been three releases into a 380 ha enclosure free of Red Foxes and feral Cats in Waychinicup National Park (J. Friend pers. comm.).

A Recovery Plan (Friend 2004) includes the actions:

·         Monitor known populations

·         Protect existing and reintroduced populations from threatening processes

·         Survey to locate further populations

·         Maintain a captive-breeding colony to produce stock for translocation

·         Translocate captive-bred and/or wild stock to establish at least three further self-sustaining mainland populations

·         Carry out genetic monitoring and management of reintroduced populations. This has not commenced yet due to lack of funding

·         Encourage community involvement in Dibbler conservation

·         Improve knowledge to underpin Dibbler recovery.

Implementation of the recovery plan is well advanced and is coordinated by the Dibbler Recovery Team. Monitoring at Peniup Nature Reserve and on the Jurien Bay Islands is carried out as funding permits. Regular aerial baiting for fox control is conducted in Fitzgerald River National Park as part of ‘Western Shield’. Aerial baiting is also carried out at Waychinicup National Park. Operational feral Cat control is not yet possible. Boullanger and Whitlock Islands are regularly visited and Escape Island sometimes visited by recreational boat users from Jurien; educational information is provided at boat ramps and Department of Environment and Conservation (DEC) staff check the islands regularly. Eradication of the House Mouse populations from the islands is proposed. Fire management in Fitzgerald River National Park is carried under the Fitzgerald River National Park Management Plan (Moore et al. 1991), which recognises the needs of Dibblers and other threatened fauna requiring long-unburnt vegetation, including Western Bristlebirds Dasyornis longirostris and Western Ground Parrots Pezoporus flaviventris. Fire management of Peniup is carried out by DEC’s Albany District and is aimed at keeping most of the reserve in a long-unburnt state, while recognising the concerns of neighbouring landholders. The Turquoise Coast Island Nature Reserves Draft Management Plan 2004 (CALM 2004) prescribes total fire exclusion from the islands and lays out a rapid response procedure to extinguish wildfire if it occurs. Fitzgerald River National Park has small areas of infestation by Phytophthora and there is ongoing work to control it and prevent its spread. A captive breeding colony is maintained at Perth Zoo and supplies >50 animals of mainland stock for translocation each year. It is regularly supplemented with Dibblers from the wild. The large increase in young produced in 2010 at Perth Zoo was due to a new pairing and weaning technique, which so far has proven to increase the output of the colony whilst keeping husbandry costs constant. A translocation to the Stirling Range National Park failed and a mainland translocation is under way to the 380 ha Waychinicup National Park enclosure (mainland island) built for Gilbert’s Potoroos Potorous gilbertii. The Malleefowl Preservation Group is involved in monitoring the subpopulation at Peniup and other community volunteers assist with the monitoring of the Jurien Bay island subpopulations. There has been considerable research carried out mainly through The University of Western Australia, elucidating aspects of genetics and the ecology of the Dibbler and other vertebrates on the islands where it occurs.

Since rediscovery in 1967, there have been numerous searches for Dibblers on the mainland, often without success, even at locations where specimens had been obtained opportunistically (e.g. Woolley and Valente 1982). Discovery of relatively abundant island subpopulations in 1985 led to several studies on the species’ biology and ecology, captive breeding (Lambert and Mills 2006) and an introduction to Escape Island, which is free from introduced mammals. Discovery in Fitzgerald River National Park in 1984 led to further studies, captive breeding and translocations.

All areas where Dibblers are known to occur are conservation reserves managed by the Western Australian Department of Environment and Conservation, which conducts ongoing research and management of the Dibbler. In areas occupied by Dibblers, management focuses on maintaining significant areas of long-unburnt habitat and preventing the spread of Phytophthora dieback. Volunteers are involved in translocations and monitoring. Current management aligns to actions in the Recovery Plan (Friend 2004).