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Cape York Peninsula Land Use Strategy

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Areas of Conservation Significance on Cape York Peninsula

Cape York Peninsula Land Use Strategy
Abrahams, H., Mulvaney, M., Glasco, D., & Bugg, A.
Office of the Co-ordinator General of Queensland
Australian Heritage Commission, March 1995


Areas of Conservation Significance on Cape York Peninsula

17.0 Areas of Significance for Rare and Threatened Plant and Animal Species

In a similar fashion to the analysis in Section 16 this section considers species and associated areas important for them. However, Criterion B (Areas important because they possess uncommon, rare or endangered aspects of Australia's natural history) is the criterion on which the species considered in the section are related.

17.1 Rare and Threatened Plant Species

There are 379 taxa considered to be rare and threatened that are known to occur on Cape York Peninsula, north of 16 o S (Neldner & Clarkson 1994) (See Appendix 6). These include 15 endangered, 49 vulnerable, 213 rare and 102 poorly known but suspected of being at risk species. The threat categories used in the analysis accord with the International Union for the Conservation of Nature (IUCN) Red Data Book Categories, as described in Briggs and Leigh (1988). The relevant categories are:

E = endangered - species in serious risk of disappearing from the wild state within one or two decades if causal factors continue to operate;

V = vulnerable - species not presently Endangered but at risk of disappearing from the wild over a longer period (20-50 years) through continued depletion, or which largely occur on sites likely to experiences changes in land use that would threatened the survival of the species in the wild;

R = Rare - species which are rare in Australia but which overall are not currently considered Endangered or Vulnerable; and

K = Poorly Known - species that are suspected, but not definitely known, to belong to any of the above categories.

The list of rare and threatened plants from Cape York Peninsula is yet to be reviewed in light of the added plant distribution information collected as part of the CYPLUS studies. It is likely that there will be many changes in the lists. However these changes are likely to be mainly in the category of threat, while the relatively few deletions from the list are likely to roughly equate to additions of newly described species (John Clarkson, Qld Herbarium, pers. comm. 1994).

Briggs and Leigh (1988) provide a map of the number of rare and threatened species found in each of 80 Australian phytogeographical areas (see Figure 17.1). The number of rare and threatened species identified in the CYPLUS study area is greater than that of any of these regions (outside the North-East Queensland area of which the CYPLUS area is a part). Only the adjoining Wet Tropical Forests and the large south-west Western Australia biogeographic areas contain comparable numbers of rare and threatened species. Thus Cape York Peninsula is amongst the most important areas in Australia for rare and threatened plant species.

The location of all plant species currently listed as rare or threatened on Cape York Peninsula are shown in Figure 17.2. Plots of known locations of individual endangered species and of all vulnerable species are given in Cofinas et al. (1994). As evident in the plots, rare and threatened taxa are most common on the east and north of the Peninsula. The known locations of rare and threatened plants are particularly concentrated in the following areas:

The concentrations of some of these areas may be more a result of collection effort, rather than ecological consideration.

A GIS point coverage of all records of rare and threatened plant species has been provided. The location of any rare or threatened plant species is taken to be of conservation significance. The coverage also provides the category of threat..

The numbers of rare and threatened plant taxa recorded in each of the broad vegetation groups on the Peninsula are given in Appendix 8. As is evident in the table, the following broad vegetation groups support the largest number of rare and threatened species:

Eighteen broad vegetation groups support 25 or more rare and threatened species. Thirty-three of the 80 phytogeographical regions of Australia (Briggs & Leigh 1988) support less than 25 rare or threatened plant species, which provides some context to considering Appendix 8.

The CORVEG database contains site records of 137 rare and threatened species. The vegetation classes that support a particularly large number of rare and threatened species are all closed forests and include:

The distribution of these classes on the Peninsula is shown on Figure 17.3, while the number of rare and threatened species recorded for each vegetation class, within the CORVEG database, is given in Appendix 9.

The large number of rare and threatened plant species found on the Peninsula is thought to be due to the diversity of habitats found there, particularly the diversity and extent of rainforest and heathland areas. The major threatening process leading to the rating of species as either Endangered or Vulnerable is the illegal collection of epiphytic orchids, epiphytic ferns and palms (John Briggs, CSIRO, 1995, pers. comm.)

17.2 Rare or Threatened Terrestrial Vertebrate Fauna

A data set of the recorded locations on Cape York Peninsula of the rare or threatened vertebrate species, as listed in the schedule to the Nature Conservation Act 1992 of the Queensland Government, was established by the Queensland Department of Environment and Heritage and described in Young (1995) (see Appendix 7).

The recorded locations of rare or threatened vertebrate fauna are illustrated in Figure 17.4. The data sets searched to create these records are detailed within Glasco, Bolton and Bryett (1995), which is the report on the CYPLUS Natural Resources Analysis Program project No. NR19.

The areas of greatest concentration are the Wet Tropical Forests, the McIlwraith Range, Iron Range, Lockerbie Scrub and Weipa. The first four areas all contain species of restricted distribution, while the records from the Weipa area tend to be of widespread species, and the concentration recorded here is likely to be a result of collection effort.

17.2.1 Nationally endangered terrestrial vertebrate species.

Eleven species have been recorded within the CYPLUS study area, that are listed as endangered under the schedule to the Nature Conservation Act 1992, or the Commonwealth Endangered Species Protection Act 1992. These species are listed in Appendix 7.

Four of the eleven endangered species are frogs which occur in the extreme south-east corner of the study area and are endemic to the Wet Tropical Forests biogeographic area. The Sharp-snouted Torrent Frog (Taudactylus acutirostris), Torrent Tree Frog (Litoria nannotis), Litoria rheocola and Nyctimystes dayi, are all found in or by streams in lowland and/or upland rainforests. Within the study area, the Wet Tropical Forests near Mt Amos and Mt Finnigan are significant habitat for these species.

A broad unvegetated sandbank on the northern side of the mouth of the south arm of the Mitchell River supports the largest known breeding colony of the Little Tern (Sterna albifrons sinensis) on Cape York Peninsula. Fifty birds in breeding plumage have been recorded here, making the site one of the top ten nesting locations of the sub-species in Australia (Taplin 1990, Starks 1992). In 1989 thirty-six birds, including twelve in breeding plumage, were recorded on a sandspit at the mouth of Janie Creek. The twelve birds represented a little over 1% of the total Australian population in breeding plumage recorded for 1989 (Taplin 1990). During 1989 most of northern and eastern Australia was surveyed for populations of the Little Tern. Other areas on Cape York Peninsula from where nationally large roosting populations were recorded include the mouth of the McDonald River (51 birds), Campbell Point (22 birds) the mouth of Chester River (21 birds), the mouth of McIvor River (40 birds) and an un-named point at 150 10'S 1450 14'E (Starks 1992). A roost of about 100 individuals has also been recorded from Lowrie Island in the northern Great Barrier Reef area (DEH 1994).

The Golden-shouldered Parrot (Psephotus chrysopterygius) once occurred over much of the central Peninsula, but is now only known from a few small populations in the Musgrave area and west of the Lynd River (south of the CYPLUS study area). The total population is estimated at about 250 pairs. It is thought that the disappearance of the Parrot over much of its former range may be caused by a decline in wet season burns and a lack of naturally rocky or open areas. Current grazing levels are considered not to threaten the Parrot populations but higher stocking rates may reduce food availability. A recovery plan is currently being prepared for the species (Garnett & Crowley 1994).
(Map of suitable habitat for Golden-shouldered Parrot
NR19 Report on Golden-shouldered Parrot status)

The genus Erythrotriorchis is endemic to Australia and monospecific. The CYPLUS data-base contains two records of the Red Goshawk (Erythrotriorchis radiatus). It is a woodland bird with extremely sparse populations that nests in trees greater than 20m in height, and within 1km of a watercourse or wetland. It is estimated that there are about 350 pairs of Red Goshawk remaining in Australia, compared to an historical population of about 440 pairs.

The decline in numbers has occurred south of 150 and is thought to be related to large scale deforestation. There is also concern that a combination of fire and grazing may in the long term result in a lower density of prey and an unsustainable loss of nest trees (Garnett 1993). Aumann and Baker-Gabb (1991) surveyed nesting sites in the Northern Territory and Western Australia. An analysis of the climate of recorded nesting areas in these areas predicted that in Queensland, core nesting habitat would generally be south of Cape York Peninsula. Nevertheless there is a long standing and repeated record of a nesting location near the lower reaches of the Wenlock River. The Red Goshawk mostly nest in tall riparian trees, and generally forage within coastal and subcoastal tall open forests and woodlands, and on savannas traversed by wooded or forested rivers.

The woodlands, tall open forest and riverine forests on Cape York Peninsula are amongst the least disturbed in Australia and those catchments on the west of the Peninsula that are between the Mitchell and Wenlock Rivers, together with the Lakefield area are likely to be important for the conservation of this endangered species, either as foraging or nesting habitat (David Baker-Gabb RAOU pers. comm. 1994).

There are also two records of the northern sub-species of the Star Finch (Neochmia ruficauda clarescens) in the CYPLUS fauna data-base (Glasco et al 1995). The central eastern (Lakefield) and western coasts of Cape York Peninsula are some of the few areas in Queensland where the Finch has been recently sighted (Blakkers et al 1984). The Finch's preferred habitat is dense grass and rushes growing beside freshwater. It is considered that the most likely reason for the decline in the Queensland population is degradation of habitat by stock and feral animals, particularly during the dry season. Wilderness or little disturbed wetland areas in the Lakefield area and on the central west coast of the Peninsula are likely to be important to the continued survival of this sub-species in Queensland. The Star Finch is rare throughout Australia but may be locally common in the Northern Territory or Western Australia (Garnett 1993).

Cape York Peninsula is not a major habitat of the remaining endangered species found there, namely the Loggerhead Turtle (Caretta caretta), Gouldian Finch (Erythrura gouldiae), and Northern Bettong (Bettongia tropica). The recorded locations for these species are however available within the CYPLUS GIS and should be considered in any detailed land use planning.

Figure 17.5 provides a plot of the habitat on Cape York Peninsula that is of significance for endangered fauna. It consists of the major Little Tern breeding and non-breeding records of Starks (1992), the land tenure properties identified by Garnett and Crowley (1994) as being important for the Golden-shouldered Parrot, and the forest types of the Wet Tropical region in which endangered frog species have been recorded.

17.2.2 Vulnerable terrestrial vertebrate species.

Sixteen vulnerable species have been recorded within the CYPLUS study area.

Three of these vulnerable species are turtles. The significance of Cape York Peninsula to turtle species in general is detailed at Section 17.7 of this report, and shown in Figure 17.9. In summary, Crab Island is the most important nesting site of the Flatback Turtle (Natator depressus): islands just off the north-east coast of Cape York Peninsula contain medium-sized (in an international context) nesting beaches of the Hawksbill Turtle (Eretmochelys imbricata); while the seagrass beds identified in the seagrass GIS coverage are likely to be important feeding habitat of the Green Turtle (Chelonia mydas).

The importance of the CYPLUS study area to the Saltwater Crocodile (Crocodylus porosus) is described in Section 17.5, and illustrated in Figure 17.11. The lower sections of the Wenlock and Dulcie rivers and the Jacky Jacky Creek area are particularly important breeding locations.

The northern Great Barrier Reef area, the northern and eastern shores of Cape York Peninsula, together with the shores of the Torres Strait Islands form an area of international significance for the Beach Stone-curlew (Burhinus giganteus), as it supports over 5% of estimated East Asian-Australasian population. It is the only area in Australia that is recognised as being significant for this species (Watkins 1993). The species occurs singly or in small groups along the coastline and is likely to be more common on offshore islands, and those parts of the mainland little disturbed by humans, pigs or cats (Driscoll 1994b).

The Southern Cassowary (Casuarius casuarius johnsonii) is largely confined to rainforest from the tip of Cape York to the southern extent of the McIlwraith Range and then from Cooktown south to Townsville. The population south of Cooktown is estimated at about 3000 individuals (Crome & Moore 1990). There is not enough information to estimate the size of the northern population.

The Eclectus Parrot (Eclectus roratus macgillivrayi) occurs only in the Iron and McIlwraith ranges between the Pascoe and Rocky Rivers.

The northern or white-bellied subspecies of the Crimson Finch (Neochmia phaeton evagelinae) has only been recently recorded on the western coast of Cape York Peninsula, with a core area being in a narrow coastal strip between the Archer River south to Magnificent Creek near Kowanyama. It has been recently recorded as locally abundant in the Edward River area, in long perennial grass beside watercourses. Much of this habitat has been removed by feral pigs and stock grazing, while the riparian vegetation along the Mitchell River is being smothered by Rubber Vine Cryptostegia grandis.

The Fawn Horseshoe Bat (Hipposideros cervinus) is a rainforest generalist occurring on north-east Cape York Peninsula. It roosts in caves and mine shafts and feeds in rainforest and riverine areas.

The four other vulnerable bat species, Greater Wart-nosed Horseshoe Bat (Hipposideros semoni), Spectacled Flying-fox (Pteropus conspicillatus), Northern Sheathtail-bat (Taphozous australis) and Ghost Bat (Macroderma gigas) have more widespread distributions.

The Mitchell-Palmer Karst System in the south of the CYPLUS area is a significant habitat of the Ghost Bat with 64 individuals counted there in 1994 (Peter Berrill, Central Queensland Speleological Society, pers. comm. 1994). The Northern Sheathtail-bat is also known to roost in this cave system (Central Queensland Spelaeological Society & QNPWS 1990), while a small colony has also been recorded in a sea cave near Captain Billy Landing (Coles & Lumsden 1993). Significant numbers of Ghost Bats are also known to roost on Birthday Mountain and Black Mountain (DEH 1995).

The recorded locations for the Black-breasted Button-quail (Turnix melanogaster), Northern Hopping Mouse (Notomys aquilo),and Yakka Skink (Egernia rugosa), are given within the GIS rare and threatened coverage provided to CYPLUS. Precise habitat information is not available, but the vegetation class polygons (not the whole class) in which a species was recorded is indicative of important habitat..

Figure 17.6 shows the location of habitat likely to be significant for vulnerable species. This coverage includes: the coastline of the Torres Strait Islands and Duifken Point to Cape Weymouth which is an extensive habitat of the Beach Stone-curlew; the Wet Tropical closed forests of the study area; the mid-Peninsula and north-eastern rainforests; the sub-coastal rivers and creeks between and including the Edward and Holroyd Rivers; the sea-caves at Captain Billy's Landing; the Mitchell - Palmer Karst System; and the vegetation polygons in which the Black-breasted Button-quail, Northern Hopping Mouse (Notomys aquilo), and Yakka Skink (Egernia rugosa) have been recorded.

17.2.3 Rare terrestrial vertebrate species.

There are fifty-eight rare species recorded on Cape York Peninsula. Many of these species are largely restricted to rainforest areas. Rare species confined to the Wet Tropical Forests, within the CYPLUS study area, include the Tapping Nursery Frog(Cophixalus concinnus), Bloomfield Nursery Frog (Cophixalus exiguus), Cricket Chirper frog (Sphenophryne fryi,) Spotted-tail Quoll (Dasyurus maculatus), Bennett's Tree Kangaroo (Dendrolagus bennettianus), Caramel Ringtail Possum (Pseudocheirus cinereus), a skink (Eulamprus tigrinus), a skink (Lygisaurus laevis), Blue-faced Finch (Erythrura trichroa) and Double-eyed Fig Parrot (Cyclopsitta diophthalma macleayana).

Rare species confined to the Central Peninsula (McIlwraith - Iron Range) rainforests and summit vegetation, within the CYPLUS study area, include the Northern Nursery Frog (Cophixalus crepitans), Cape York Nursery Frog (Cophixalus peninsularis), Scrub Rocket Frog (Litoria longirostris), Cinnamon Antechinus (Antechinus leo), Grey Cuscus (Phalanger intercastellanus), Green Tree Python (Chondropython viridis), a gecko (Saltuarius occultus), the goanna Varanus teriae and Double-eyed Fig Parrot (Cyclopsitta diophthalma marshalli).

The skink Eugongylus rufescens is a rainforest specialist occurring in the Lockerbie Scrub.

The Green-eyed Tree Frog, Litoria genimaculata, is largely confined to the Central and Wet Tropical rainforests on the Peninsula.

The lizard, Emoia atrocostata, is only known from the northern rainforest and on beach laterites on some of the islands of Torres Strait.

The Spotted Cuscus (Spilocuscus maculatus) occurs in the central and northern rainforests and also in riverine forests, interfluvial evergreen vine forest and patches of semi-deciduous vine thicket south and west to the lower reaches of the Archer River (Winter & Lethbridge 1994).

A number of rare species are restricted to boulder and/or cliff habitats. The Cape York Rock Wallaby Petrogale coenensis has a fragmented central Peninsula distribution on rocky mountains and hills. The Boulder Nursery Frog (Cophixalus saxatilis), the skink (Nactus galgajuga ) and the skink (Carlia scirtetis ) all only occur on Black Mountain, a large boulder mountain south of Cooktown. A similar boulder habitat occurs on Cape Melville and the skink Cryptoblepharus fuhni, and a newly described frog, are restricted to this area.

The skink (Anomalopus pluto) occurs in the sandy heathland and monsoon forest areas of the north-east Peninsula and on the sandstones of the Glennie Tableland.

The skinks Lerista ingrami and Ctenotus rawlinsoni are only known from the sandy heathlands of the Cape Bedford - Cape Flattery dune fields.

The inland sub-species of the Cave Swiftlet (Collocalia spodiopygia chillagoensis) is only known to nest in the Chillagoe and Mitchell-Palmer River karsts. A population of 2000 has been estimated for the Chillagoe area. No estimates can be made for the Mitchell-Palmer area though nests of up to 50 birds have been recorded in individual caves (DEH 1992, Chillagoe Caving Club 1988).

The Cape York Peninsula sub-species of the Rufous Owl (Ninox rufa meesi) probably roosts and nests in gallery rainforest and dense paperbark thickets (Garnett 1993). Four of the six recorded sightings (within the CYPLUS fauna data sets) of the species are in the Iron Range - McIlwraith Range area.

The Palm Cockatoo (Probosciger aterrimus aterrimus) is widespread above 14o30'S, and tends to occupy the ecotone between rainforest and open tropical woodland dominated principally by paperbarks (Melaleuca). The hollow nesting trees are particularly vulnerable to fire in the dry season (Garnett 1993).

The rare turtle, Emydura subglobosa is known in Australia only from the far north of Cape York Peninsula (Cogger 1992, DEH 1995).

The rare skink, Lygisaurus tanneri, has a restricted distribution centred on Cooktown (Cogger 1992).

The Diadem Horseshoe Bat (Hipposideros diadema) is common within the Mitchell Palmer Karst (Central Queensland Spelaeological Society & QNPWS 1990).

The lizard, Menetia koshlandae, is only known from woodland just north of the Palmer River Crossing on the Cape Development Road (DEH 1995).

Ramphotyphlops chamodraceane is a recently described blind snake collected in the Weipa area (DEH 1995).

The Eastern Curlew (Numenius madagascariensis) occurs on Cape York Peninsula, but there are no major habitats of this species on the Peninsula (Watkins 1993, Driscoll 1994b).

The Black-necked Stork (Ephippiorhynchus asiaticus) is widespread across the Peninsula. The wetland area between the Holroyd and Archer Rivers may be an important dry season refuge for the species on Cape York Peninsula (Driscoll 1994b). This is probably also the case for the Radjah Shelduck (Tadorna radjah) (Peter Driscoll, 1994, pers. comm.).

The rocky and sandy shores of the northern Great Barrier Reef area and the adjoining coastline of Cape York Peninsula are a particularly important habitat for a northern sub-species of the Sooty Oystercatcher (Haematopus fuliginosus opthalmicus), which is estimated to have a total population of only 1000 individuals. The area supports over 1% of the total estimated global population of the species (Watkins 1993, Driscoll 1994).

The Cotton Pygmy-Goose (Nettapus coromandelianus) reaches its northern distribution limit in the Lakefield area, and the wetlands here are the only important habitat of the species on Cape York Peninsula (Driscoll 1994b).

All recorded sites for rare and threatened species are provided with the GIS coverage provided as part of the CYPLUS Conservation and Natural Heritage Assessment Project.

Figure 17.7 shows indicative important habitat for rare species. This coverage includes: the mid-Peninsula and north-eastern rainforests; the wet tropical closed forests; Cape Melville: Black Mountain; the Cape Bedford - Cape Flattery dunefield; the Mitchell - Palmer Karst System; the Starke and north-east coastlines; and the vegetation polygons in which the Cotton Pygmy-Goose, Ramphotyphlops chamodraceane , Menetia koshlandae, Lygisaurus tanneri, Emydura subglobosa, Palm Cockatoo, Rufous Owl, Anomalopus pluto, Petrogale coenensis, Spotted Cuscus, Emoia atrocostata, and Litoria genimaculata have been recorded. The large polygon coverage in the Weipa area, is mainly due to several records of the Palm Cockatoo in this area.

17.2.4 Rare and uncommon fish and fish communities

Herbert et al (1994) conducted a fish fauna survey of Cape York Peninsula as part of the CYPLUS Natural Resources Assessment Program NR10. The only rare species identified in the survey was the Short-finned Catfish (Neosilurus brevidorsalis). This Fish was collected from the Olive, Claudie and Lockhart Rivers and is also known from the Jackson and Jardine Rivers at the northern tip of Cape York Peninsula. The Short-finned Catfish is known only to occur on Cape York Peninsula and in New Guinea (Allen 1989).

The fish survey also identified a number of species that appear to be restricted to confined areas and then only occur in low numbers. The Fimbriate Gudgeon (Oxyeleotris fimbriatus) was collected from the Wenlock and Olive Rivers and is also known from the Jackson and Dalhunty Rivers on the north-west of the Peninsula. Obbes' Catfish (Porochilus obbesi) was collected in the Olive River, and is also known from the Jardine, Watson and Jacky Jacky basins. Rendahls Catfish (Porochilus rendahli) was collected in large numbers in Three Quarter Mile Lake, at Silver Plains. A few were collected in lagoons near the Endeavour, Wenlock, Archer, Holroyd and Palmer Rivers, while the species is also known from the Jardine River and the Normanby complex. Delicate Blue-eyes (Pseudomugi tenellus) were collected from Scrubby Creek, and are also known from the Jardine, Watson and Edward Rivers. The Claudie River is the only known habitat of the Spot-fin Gobies (Redigobius chrysosoma) on Cape York Peninsula. Freshwater Anchovies (Thryssa scratchleyi) were only recorded from a few locations in the Archer River catchment. Buffon's River Garfish (Zenarchopterus buffonis) is known from the Embley Estuary and was recorded during the fish survey from the Wenlock River.

The dunefield lakes near Shadd Point and Orford Bay, and on the Shelburne Bay and Cape Flattery dune fields each contain a unique fish assemblage, and sometimes species far outside their normal distribution. Other unique environments are found on small creeks or lagoons away from major rivers. Unique fish assemblages are found at Scrubby Creek/Three Quarter Mile Lake, Ronnie's Rocky Creek, Black Creek, Kupandhangan Swamp near Weipa and a creek near Bolt Head.

Figure 17.8 shows the river systems important for rare and uncommon fish and other significant conservation attributes discussed later in this report. It should be noted that the survey of Herbert et al (1994) did not cover the entire Peninsula and survey periods on specific river systems did not reflect seasonal changes.

17.3 Turtles

The four species of turtles found in the CYPLUS area are considered to be rare or endangered in either an international, national or State context. The turtles are therefore considered under Sub-Criterion B1, while significant breeding and feeding areas for all the species are important under Sub-Criterion A2 (Importance for Maintenance of Existing Ecological Processes). In this assessment the DEH turtles data-set (locations and numbers of breeding records) was used in addition to a number of key references (Harris 1994, Miller 1994, Miller & Limpus 1990, and Parmenter 1994).

Significant feeding or nesting populations of four species of turtles occur within or are adjacent to the Cape York Peninsula Land Use Strategy area. The area includes significant feeding habitat or the Green Turtle (Chelonia mydas) and important nesting sites of the Flatback (Natator depressus), Hawksbill (Eretmochelys imbricata) and Olive Ridley (Lepidochelys olivacea) turtles. Figure 17.9 shows the significant locations for turtles.

17.3.1 Flatback Turtle Nesting Site - Crab Island.

Crab Island, just off the north west coast of the Peninsula, supports the largest known Flatback Turtle (Natator depressus) rookery. The Flatback is almost totally confined to the Australian continental shelf and its breeding is restricted to Australia. Annual nesting numbers at Crab Island are in the order of 1 000 to 2 000 individuals a year. Numerous Flatback Turtles have also been observed mating in the shallow water adjacent to the island, and the waters are likely to be an important breeding location.

The Hawksbill (Eretmochelys imbricata) and Olive Ridley (Lepidochelys olivacea) Turtles have also been recorded nesting on Crab Island. Both of these turtles are listed as nationally vulnerable under the Endangered Species Protection Act 1992.

The condition of the island is natural with no major feral predators of turtle eggs known. Residents from adjacent communities on the mainland collect eggs on a regular basis during nesting season, and some adult turtles are harvested. The foraging distribution of the turtles using the Crab Island rookery is not known. Nankeen Night Herons (Nycticorax caledonicus) and Silver Gulls (Larus novaehollandiae) prey on the turtle hatchlings, while a number of adult Estuarine Crocodiles (Crocodylus porosus) are resident on the island.

17.3.2 Hawksbill nesting sites.

The Hawksbill Turtle (Eretmochelys imbricata) is listed as nationally vulnerable under the Endangered Species Protection Act 1992. It is considered to be internationally endangered. The Torres Strait and northern Great Barrier Reef region constitutes one of the few remaining large nesting populations for the species worldwide. It is estimated that over three thousand females may nest annually within the region. The major regional rookeries are well outside the CYPLUS study area, on Long, Aukane, Mimi and Kabbikane Islands/Islets. However there are several medium and minor nesting locations within or in close vicinity to the CYPLUS study area.

Medium nesting localities are used by between 20 - 50 nesting females a year and include:

Nesting locations of minor significance are used by between 10 - 20 nesting females a year and include:

17.3.3 Green Turtle foraging areas.

The Great Barrier Reef and Torres Strait region supports a large population of Green Turtle (Chelonia mydas), which is considered to be nationally vulnerable under the Endangered Species Protection Act 1992. The Green Turtle nests on the outer barrier islands and cays, but the seagrass beds on which it feeds lie adjacent to the CYPLUS study area. The large seagrass beds in the Cape Melville-Strake region and within the Princess Charlotte Bay area are likely to support large populations of foraging Green Turtles.

17.3.4 Olive Ridley nesting habitat.

The Olive Ridley Turtle (Lepidochelys olivacea) is widely distributed in the Indo-Pacific. The Olive Ridley nests sparingly throughout the Gulf of Carpentaria and the Northern Territory. It is considered to be nationally vulnerable under the Endangered Species Protection Act 1992. The Olive Ridley has been recorded as nesting on the sandy beaches of Crab Island, the Duifken Point area (north of Weipa), and at the mouth of the Nassau and Edward Rivers.

17.4 Areas of Significance for Dugong (Dugong dugon) Habitat

The Dugong (Dugong dugon) is listed as vulnerable to extinction by the International Union for the Conservation of Nature (IUCN) and is the only herbivorous marine mammal on the Convention on International Trade in Endangered Species (CITIES). Sub-Criterion B1 and Sub-Criterion A2 apply to this section of the report.

The northern Australian population is estimated at approximately 70 000 with 12 500 in the Torres Straits and 8 000 in the northern Great Barrier Reef. A significant proportion of the global dugong population is believed to occur in northern Australia (Moreton Bay to Shark Bay); however, densities are not dissimilar in other surveyed parts of the world (Heinsohn 1991).

Although considerable research in northern Australia (Marsh et al 1984c, Marsh & Saalfeld 1989, Marsh 1990, Heinsohn 1991, Lanyon et al 1989, and Preen 1989) has focused on the dugong reproductive biology, there is still little detailed understanding of the life history and ecology of the species. The staple food of the dugong is seagrass, a number of species of which are consumed; deliberate consumption of invertebrates has also been reported in the southern areas of the dugongs range in Australia, this has not been observed in the tropics however (Heinsohn 1991).

Observation of dugong behaviour suggests all spend most of their time in the vicinity of inshore seagrass beds and have overlapping home ranges of 4 - 23 km2. Marsh and Saalfeld (1989) notes the majority were sighted in at depths of <5m. Only rarely are long-distance travels undertaken (Heinsohn 1991).

Marsh indicates that even with the most optimistic combination of life-history parameters, a low rate of natural mortality, and no man-induced mortality, a dugong population is unlikely to increase at more than about 5% per annum (Heinsohn 1991).

An analysis of areas of significance for Dugong in the CYPLUS study area, was undertaken using the Dugong observation information obtained from Morisette TESAG JCU. This data was derived from detailed air survey work, involving transects and measuring the number of animals in each 2.5 x 2.5 nautical mile grid of the near shore areas south of the Olive River. This information has been related to seagrasses as mapped by Coles et al (1985), and as described in the Marine Vegetation Analysis (Section 9.3 of this report). Relating the grid cells with a high observation rate to the associated seagrass areas has been undertaken to determine the areas of significance for this species and is mapped on Figure 17.10. The data-set does not include areas in the Torres Straits where high dugong densities are also recorded, nor is information available for the west coast of the CYPLUS area. It may be possible to include that information in the future.

Table 17.1 Dugong Grid Cell Data


Dugong    Number     Dugong   Number    
Density   of Grid   Number    of Grid   
per Grid  Cells     per Grid  Cells     
Cell                Cell                

        0      1959         0      1959 

   0.1796         2         1        78 

   0.1797         4         2        35 

   0.1803         1         3        11 

   0.2695         3         4        10 

   0.2696         2         5         1 

   0.2982         1         6         3 

   0.3466         1         7         5 

   0.3593         2         8         3 

   0.3594         1         9         2 

   0.3834         1        11         1 

   0.4898         1        12         2 

   0.5389        33        13         1 

   0.5391        24        14         1 

   0.5859         1        22         1 

   0.5966         1        25         1 

   0.6258         1        29         1 

   0.6798         1                     

   0.6949         1                     

   0.7186         2                     

   0.7698         1                     

   0.7783         1                     

   0.8084         1                     

   1.0264         1                     

   1.0778         1                     

   1.0779        11                     

   1.0783        13                     

   1.1071         1                     

   1.1104         1                     

   1.1235         1                     

   1.1578         1                     

   1.4371         1                     

   1.6168         5                     

   1.6174         5                     

1.7891         1                     

1.795         1                     

1.8364         1                     

1.8862         1                     

2.1558         3                     

2.1566         2                     

2.4261         1                     

2.6957         1                     

2.8431         1                     

2.9377         1                     

3.2336         1                     

3.4624         1                     

3.7726         3                     

3.7739         1                     

4.3131         1                     

4.8504         1                     

5.3244         1                     

5.8462         1                     

5.9283         1                     

6.4673         1                     

7.0062         1                     

7.8144         1                     

11.8566         1                     

13.4785         1                     



The calculated dugong density for each grid cell was used. Those grid cells with a density above 1.7 dugongs per cell, a clear break point in the distribution, were considered indicative of the most important areas of habitat (Table 17.1). Where the grid cells related to mapped seagrass areas those seagrasss beds were delineated as areas of significance. Figure 17.10 shows these areas and in addition the high density grid cells in areas where there was no seagrass mapped.

The important difference between this information and the Marine Vegetation areas of significance (Figure 9.1) is the inclusion of the seagrasses to the north of Cape Sidmouth as being of particular habitat significance for dugongs. The few grid cells that occur where no seagrass is mapped may indicate areas where seagrass beds deeper than the 20m mapping limit are located.

17.5 Significant Locations for Crocodiles on Cape York Peninsula

Figure 17.11 shows areas significant for estuarine crocodiles on the Peninsula. The sites, as mapped are described from north to south, below. Magnusson et al (1980) and Taplin (1987) and Jeff Miller QDEH (pers. comm. [1994]) have provided the basis for this report. Crocodiles are considered nationally vulnerable and thus are considered under Sub-Criterion B1 and their breeding habitats under Sub-Criterion A2.

17.5.1 Jardine River Wetlands and Jacky Jacky Creek.

This area covers the Jardine River system including the Jardine Swamps, Jardine River National Park and Jacky Jacky Creek system.

These environments are significant breeding sites for the Estuarine Crocodile (Crocodylus porosus) because they are not prone to extensive flooding events, the vegetation is suitable for nesting, and disturbance is minimal. The adult population of the Jardine River and Jacky Jacky Creek Systems represent the largest breeding populations known in Queensland.

The area is characterised by extensive beach ridges and estuarine habitats with mangrove forests and permanent freshwater wetlands associated with the Jardine River and Jacky Jacky Creek. The freshwater swamps support sedge and grassland communities under a canopy of Melaleuca and monsoon vine forest. These areas are kept moist by seepage, and generally are not subject to the catastrophic flooding common on the Gulf Plains, due to the relatively higher elevation afforded by the Weipa Plateau. The area is remote from major settlement and is generally undisturbed. Extensive areas are available for habitation by adult Crocodylus porosus and many of the wetlands are suitable for nesting sites.

The Jardine River System considered here is an area of high wilderness quality, in excellent condition. No immediate disturbances or threats known.

17.5.2 Wenlock and Dulcie River Systems.

This includes the Wenlock and Dulcie River Systems inland to the Weipa Plateau and associated ranges. Magnusson et al. (1980), report that the best areas of crocodile habitat occur at the following grid references: 508451, 506442-506436, 505434, 528433, 521432, 514444, 512451 for the Wenlock River, and 529471, 526468-523484 on the Dulcie River.

Along with the Jardine River Wetlands and Jacky Jacky Creek area, these systems represent significant breeding sites for the estuarine crocodile (Crocodylus porosus) because they are not prone to the extensive flooding events typical of the southern Gulf Plains areas, the vegetation is suitable for nesting, and disturbance is minimal. Surveys of the area have revealed a large population (588 individuals in 145 km of waterway in 1985), with many adults and a substantial recruitment of hatchlings. This area contains one of the largest breeding populations of crocodiles in Queensland.

The lower and middle reaches of the Wenlock River and the lower reaches of the Dulcie River are characterised by permanent swamps with ferns, sedges and palms under a canopy of Melaleuca. These areas are generally not subject to flooding due to their relatively high relief. Extensive areas suitable for nesting are located at these sites, and several nests have been sighted during survey work. A large variety of habitats suitable for adult crocodiles have been noted throughout.

Again this Wenlock river area is of high wilderness quality, in excellent condition. No immediate disturbances or threats known.

17.5.3 Iron Range National Park and Lockhart River Mangrove Swamps.

This region provides numerous small, permanent swamps which are suitable for the nesting and breeding of C. porosus. The extensive mangrove community of the Lockhart River estuary is one of the few locations above Cooktown to support moderate to low numbers of adult crocodiles by providing a suitable habitat and food supply. The area is in excellent condition.

The north-east coast of Cape York Peninsula is poorly researched for crocodile habitat and population demographics. However, preliminary surveys around the Lockhart River estuary, and in the waterways of the Iron Range National Park suggest that this area would be suitable crocodile habitat. The Lockhart River estuary is dominated by an extensive and diverse mangrove community which provides suitable habitat and feeding grounds for adult Estuarine Crocodiles (C. porosus). The high relief of the Iron Range National Park, and the relatively high and consistent rainfall patterns of the area, have favoured the development of small, permanent coastal swamps which are thought to be suitable as nesting sites.

17.5.4 Lakefield National Park.

Due to the size of the Lakefield National Park (537 000 ha), and the presence of extensive riparian thickets along most of the waterways, this area is considered to have a high conservation value in terms of protection of the habitat and feeding grounds of adult Estuarine Crocodile.

Three major river systems pass through the Lakefield National Park area - Normanby, Kennedy, and Morehead Rivers. Extensive wetlands occur throughout the Park including riparian thickets along the riverine systems, permanent swamps and lagoons. Perennial, spring-fed wetlands suitable for Estuarine Crocodile (C. porosus) nesting sites are not known from the area at this time, although marginal quality nesting habitat is present in mid-sections of the North Kennedy and Normanby Rivers. The coastal areas are low-lying and subject to flooding, and some of the riverine stretches become hypersaline during the dry season. Based on the limited survey data that is currently available, the Lakefield area supports a modest number of adult C. porosus. However, recruitment of juveniles into the area has been reported, and further surveys may reveal an increase in the population since the last surveys of the 1980s. The extensive mangrove communities of the Normanby River may provide good opportunities for adult crocodile feeding grounds. The Freshwater Crocodile (C. johnstoni), occurs in permanent waterbodies of the inland sections of the Park.

The Park is generally good to excellent condition, although human population pressures from tourism (removal of animals near camping sites) and degradation of freshwater lagoons outside the park are occurring.

17.5.5 Other Sites.

According to Jeff Miller of the Queensland Department of Environment and Heritage, the only other Queensland sites with significant C. porosus habitat, comparable to those on the Peninsula, include Eubenangee Swamp and the Hinchinbrook coast (Hull River, Edmund Kennedy National Park and Hinchinbrook Channel). These locations do not fall into the CYPLUS area and will not be discussed further.

Once upstream of the tidal boundary, all the waterways of the central region of Cape York Peninsula, down to Einasleigh, contain significant populations of the freshwater crocodile (Crocodylus johnstoni). At this stage, however, no particular areas of significance for this species have been recognised amongst those rivers within the CYPLUS study area.