Biodiveristy_State of Environment report - Mission Beach Cassowaries

not survive.This makes available habitat the key issue in determiningcassowary numbers. Further reductions in habitat are asignificant hazard to the viability of the cassowarypopulation.It is likely that the shape and connectivity of habitat will alsodetermine whether cassowaries can successfully utilise it asa territory. Both the extent and structure of habitat remainingis under threat from development.Dry seasons in the rainforest or cyclone events can alsoadversely affect cassowaries, when their available foodsources from fruit are reduced.Cassowaries are also affected by disease. It is known thatsome birds have respiratory diseases. Some birds can survivethis, but then pass the disease on. An example is one malebird at Mission Beach known to raise a chick each year thatsubsequently succumbs to the disease before reachingmaturity. Further research is required into the cassowarydiseases.ConditionCassowary numbers are not known. QPWS have positivelyidentified 25 known birds in the region. C4 estimate anumber of approximately 40 adult birds in the MissionBeach area.Studies carried out in 1992-1998 in the Daintree regiondetermined that most cassowaries maintain a home range of1-3 km 2 (Moore and Moore, 1998). Similar densitiesoccurred at Mission Beach. Moore and Moore (1998)estimated a population of 76-81 adult birds in the MissionBeach area, from coast through to hinterland, based onsurvey work and previous studies. They note that habitatclearing has reduced this population from previous levelsdetermined by Bentrupperbaumer (1992).Whilst there are large natural areas around Mission Beach,the cassowaries do not utilise the parts that are steeplysloped mountainous areas (Allanson, pers comm.). They relyupon a reasonable grade of land, and the types of foodbearinghabitat on these areas. They are primarily a coastalspecies.A program is under development by the EPA ThreatenedSpecies Unit to monitor the population by sampling DNAfrom cassowary droppings. Unfortunately, some problemshave so far held this program back; as a number of rainforestfruits in the bird's diet contain chemicals that degrade theDNA samples.There is speculation by QPWS that a lack of geneticexchange may be affecting some portions of the cassowarypopulation. Some birds at Etty Bay are showing reducedwattle size, which could be an effect due to inbreeding.However, without genetic sampling over the regionalpopulation it is not possible to determine whether inbreedingis occurring.C4 record the number of sightings reported, mainly bytourists, of cassowaries in the Mission Beach area. Thedifficulty in interpreting this information is that it does notrepresent actual numbers, and may be a better indicator ofvisitor interest. However, the sightings are important in thatthey provide an early warning system - significant drops inCassowary - Casuarius casuarius johnsoniiTable 2.3.3a - Cassowary Sightings Source: C4 (2005)Note that Sightings will depend on the response fromtourists and locals and will vary according to visitornumbers or community interest.Recorded CassowarySightings—Mission Beach2001 2002 2003 2004Adult Males positivelyidentified (i.e. with chicks)nd 193 118 81Adults (unidentified sex) 246 188 214 136Sub adults 112 137 124 68Chicks 97 264 89 111Total 455 782 545 396the number sighted will be cause for concern.Because the cassowary population is dependent on availableterritory this is a better descriptor of the likely numbers ofbirds. A slightly greater number exists than the availablehabitat can support, due to unnatural food sources. Thisincludes waste fruit at banana plantations or orchards. Thismeans there are some fringe-dwelling cassowaries that donot have established territories. These birds won't breedsuccessfully, but do form a reserve in the case of mortalityof established birds.QPWS record cassowary deaths in the Mission Beach area.Not all incidents are recorded, as birds involved in vehiclecollisions and dog attacks usually enter the rainforest, wherethey eventually succumb to their injuries out of sight.A total of 14 birds were reported killed in 2004 in theMission Beach area (Allanson, pers comm.), mostly fromroad deaths. No dog attacks were reported during the year.It is likely that increased public awareness of the birds hasraised the number of deaths being reported (Allanson pers.comm). Table 2.3.3b describes cassowary deaths recordedsince 1993 by C4. These are mostly motor vehicle deathsand dog attacks, but also include deaths from malnutrition,which possibly indicate difficulties with successfulSource: C453