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Summary of Flatback turtle (Natator depressus) monitoring data for the Jardine River site 2012-2014 2012-2014 Compiled by Northern Peninsula Area Regional Council/Apudthama Land and Sea Ranger Group Threatened Species Unit Environment and Heritage Protection Western Cape Turtle Threat Abatement Alliance Acknowledgements This report presents the results of flatback turtle monitoring activities undertaken by the Indigenous Land and Sea Rangers working under the Northern Peninsula Area Regional Council and Apudthama Land Trust. These activities have been supported throughout by the Western Cape Turtle Threat Abatement Alliance (WCTTAA) and the Threatened species Unit of the Queensland Department of Environment and Heritage Protection. The authors would also like to acknowledge the traditional owners upon whose land these activities occurred and the Queensland Government for providing funding for monitoring activities. Most importantly, none of this would have been possible without the tireless effort and dedication of the entire ranger team. Citation Freeman, A.B., Strevens, W., Bell. I. and Karam, J. 2015. Summary of flatback turtle monitoring data for the Jardine River site 2012-2014. Page ii Cover images Alastair Freeman (top) middle and bottom (Kerry Trapnell) Table of Contents Acknowledgements ................................................................................................................................................. ii List of Figures............................................................................................................................................................ iv List of Tables ............................................................................................................................................................. iv Abbreviations............................................................................................................................................................ iv 1 Background................................................................................................................................................... 1 2 Monitoring area .......................................................................................................................................... 2 3 Methodology ............................................................................................................................................... 3 4 Results ............................................................................................................................................................ 5 5 4.1 Turtle Monitoring .............................................................................................................................. 5 4.2 Measurements .................................................................................................................................... 6 4.3 Nesting turtle distribution along transect ............................................................................... 7 4.4 Nesting .................................................................................................................................................. 8 4.5 Nesting habitat .................................................................................................................................. 9 4.6 Hatching success ............................................................................................................................ 11 4.7 Satellite tracking 2014 .................................................................................................................. 11 4.8 Other turtle species recorded.................................................................................................... 12 Discussion................................................................................................................................................... 12 Management Summary ...................................................................................................................................... 16 Page iii References cited .................................................................................................................................................... 17 List of Figures Figure 1: Study site locality in far northern Cape York .............................................................................. 2 Figure 2: Jardine River mouth monitoring transect .................................................................................... 2 Figure 3: Apudthama Land and Sea rangers tagging a flatback turtle, Jardine River mouth monitoring site (image Kerry Trapnell) ............................................................................................................ 3 Figure 4: Location of Indicator nests with data loggers on Jardine river census beach................ 4 Figure 5: Satellite tagged flatback turtle (Image Ian Bell)......................................................................... 5 Figure 6: Nesting interval (days) for returning turtles (n=114). .............................................................. 6 Figure 7: Turtle records with accurate locality data for the 2013 (n=395) and 2014 (n=606) nesting seasons......................................................................................................................................................... 7 Figure 8: Turtle nest habitat categories ........................................................................................................... 9 Figure 9: Nesting flatback turtle in foredune (Image Kerry Trapnell)................................................ 11 Figure 10: Track map of satellite tagged flatback turtles tagged in 2014 ....................................... 12 Figure 11: Pig shot in 2006 on west coast of Cape York with flat back hatchlings in stomach (Image Lee and Kerlin) ........................................................................................................................................ 14 List of Tables Table 1: Indicator nest locations and establishment and data logging dates. ................................. 4 Table 2: Summary statistics for CCL measurements for flatback turtles measured at the Jardine River monitoring site during the 2013 and 2014 monitoring seasons (excluding within season recaptures) ................................................................................................................................................... 7 Table 3: Number of flatback nests recorded on transect over three years of monitoring........... 8 Table 4: Predation levels recorded for flatback turtle nests over monitoring period .................... 8 Table 5: Number of feral pigs killed in helicopter control operations ................................................. 9 Table 6: Summary of nesting habitat recorded in 2013 and 2014 ........................................................ 9 Table 7: Summary of nest temperature data collected in 2014 .......................................................... 10 Table 8: Clutch size and nesting success recorded in the 2014 monitoring season ................... 11 Table 9: Non flatback turtle nests recorded 2012-2014. ........................................................................ 12 Abbreviations Page iv CCL EHP GPS NPARC PDA Curved carapace length Queensland Department of Environment and Heritage Protection Global Positioning System Northern Peninsula Area Regional Council Personal digital assistant 1 Background The flatback turtle (Natator depressus) is an endemic species with all rookeries confined to northern Australia from the Exmouth area of Western Australia to the south east coast of Queensland. It is currently listed as Vulnerable under the Environmental Protection and Biodiversity Conservation Act (EPBC) and Vulnerable under the Queensland Nature Conservation Act (NCA). This turtle is a species that feeds in the waters over the Australian continental shelf north to the Gulf of Papua New Guinea and coastal waters of West Papua in Indonesia. Beyond the Australian continental shelf, the species has been recorded in the coastal waters of Kei in south-eastern Maluku, Indonesia The largest breeding aggregations for this species occur on Crab Island and the adjacent west coast of Cape York Peninsula south to Kowanyama , as well as on some of the islands of western Torres Strait. Nesting also occurs along the entire Northern Territory coastline and into Western Australia as far south as Exmouth and along parts of the coastline in mid and south-east Queensland (Limpus, 2007). This population forms part of genetically distinct management unit which encompasses turtles from the western Torres Strait, Gulf of Carpentaria and Northern Territory as far west as Darwin (Fitzsimmons and Limpus, 2014). The current monitoring is part of a larger project that aims to study the breeding biology, habitat utilisation, diets and health of flatback turtles originating from Jardine River beach and Crab Island, in the Northern Peninsula Area (NPA) region, Queensland. The nesting turtle monitoring program has been established to determine what contribution flatback turtles in NPA are making to the greater flatback populations and Queensland Turtle Conservation Project. Annual monitoring of turtle nesting beaches provides valuable information about the status of nesting populations, detects changes within the population, and measures the effectiveness of planning and management tools. The Queensland Turtle Conservation (QTC) project is a long-term research, monitoring and conservation management project in operation within the Department of Environment and Heritage Protection (EHP). The data collected is collated within a central EHP database and is summarised in annual reports produced by EHP staff and volunteer team leaders. Year-round nesting, with a June to August winter peak is the norm along the western Cape York coastline with average clutch sizes of around 50 eggs (Limpus, 2007). Flatback turtles nest on the Jardine River beach and it is now a major nesting index site. Data have been collected on nesting activity at this site during the nesting seasons of 2012, 2013 and 2014. Nesting activity was monitored by Apudthama Land and Sea Rangers with the assistance of Threatened Species Unit staff from Environment and Heritage Protection. During 2013 and 2014, data on nesting turtles were also collected. This report summarises the nesting and Page 1 turtle data collected during these three monitoring seasons. 2 Monitoring area Nest monitoring occurs along the coastline adjacent to the Jardine River in far northern Cape York Peninsula (Figure 1). Turtles are monitored on the beach along a 10 kilometre transect from the western side of the mouth of the Jardine River to the tip of a small, sandy peninsula to the south west (Figure 2). Figure 1: Study site locality in far northern Cape York Page 2 Figure 2: Jardine River mouth monitoring transect 3 Methodology Monitoring of nests has occurred over three nesting seasons (2012-2014). The position, habitat and any signs of predation on nests were recorded with a handheld PDA (personal digital assistant) using Cybertracker software. Monitoring of turtles took place over a period of four and half weeks in 2013 and eight weeks in 2014. During this time rangers – and some volunteers – were based in a camp adjacent to the nesting beaches. The beaches were checked by rangers for nesting activity at intervals during the early evening and into the night. Nesting turtles were observed as they were encountered coming ashore. As each turtle began laying eggs, rangers recorded the location of nesting activity with the GPS function of the PDAs. Turtles were checked for flipper tags and tag numbers of recaptures were recorded. Untagged turtles were tagged with a flipper tag and curved carapace length (CCL) was recorded using a dress maker’s tape measure. The position of each nest on the beach was also recorded according to whether it was on or above the high tide mark, in the dunes or on the edge of the adjacent vegetation. Figure 3: Apudthama Land and Sea rangers tagging a flatback turtle, Jardine River mouth monitoring site (image Kerry Trapnell) Data loggers were placed in ten indicator nests to record temperature, of which 9 were recovered. These loggers were Thermochron (DS1921G) buttons housed in small plastic cases, as used for the storage of SD memory cards. These were placed in the top of nesting chambers after laying was completed, prior to burying of the nest. Temperature data loggers were placed in nests between July and September 2014. Details of the locations, establishment dates and start and end dates of temperature data recording are provided below (Table 1). All data loggers were programmed to record temperatures in degrees Page 3 Celsius at half hour intervals. Table 1: Indicator nest locations and establishment and data logging dates. Nest number 1 2 3 4 5 6 7 8 9 10 Latitude Longitude Date est'd Temp Start Temp End -10.9144 -10.9144 -10.9146 -10.9146 -10.9145 -10.9147 -10.9147 -10.9155 -10.9163 -10.9166 142.2023 142.2051 142.2064 142.2065 142.2059 142.1991 142.2074 142.1944 142.1917 142.1891 24/07/2014 not recovered 24/07/2014 24/07/2014 24/07/2014 3/08/2014 3/08/2014 6/08/2014 7/08/2014 2/09/2014 5/09/2004 24/07/2014 24/07/2014 24/07/2014 24/07/2014 24/07/2014 6/08/2014 6/08/2014 8/08/2014 1/09/2014 1/09/2014 5/09/2014 5/09/2014 5/09/2014 15/09/2014 15/09/2014 18/09/2014 19/09/2014 15/10/2014 The location of data loggers are shown in Figure 4. All indicator nests were located in the 4 Page 4 Figure 4: Location of Indicator nests with data loggers on Jardine river census beach most easterly 2km of the 10km census area. This may not be representative of the entire census area, though it is the area of highest density nesting, as described in the results section below. Satellite tracking is an ideal method to study migration, movement and habitat use, and sea turtles are ideal candidates to use this technology on, as they frequently come to the surface to breathe. Indeed satellite technology has been used in many turtle studies to great effect. In 2014, two satellite transmitters were purchased by the ranger program to place on flatback turtles from the Jardine River monitoring area. These were SPLASH tags, data archiving tags that transmit to the Argos satellite system. These were secured on two females using a harness system (Figure 5). Figure 5: Satellite tagged flatback turtle (Image Ian Bell) 4 Results 4.1 Turtle Monitoring From the 6th of August to the 9th September 2013 a total of 367 (not including recaptures) nesting flatback turtles were recorded and tagged during the monitoring period. Twentyfive out of the 367 turtles were recorded attempting to nest twice over the period of the monitoring. One further turtle was recorded as an inter-season nester, based on a tag scar on the flipper. Unfortunately, as the tag was not present, it was not possible to establish where this individual had originally been tagged. This was the only turtle recorded that Page 5 showed signs of having been tagged prior to 2013. Between the 8th of August and 27th September 2014 a total of 518 individual flatback turtles – not including recaptures – were recorded and tagged attempting to nest during the monitoring period. Of these 518 turtles, 89 individuals were observed attempting to nest 45 40 No of turtles recorded 35 30 25 2013 20 2014 15 10 5 0 0-5 6-10 11-15 16-20 21-25 26-30 31-35 36-40 41-45 46-50 51-55 No. of days between nesting attempts Figure 6: Nesting interval (days) for returning turtles (n=114). twice and two individuals observed three times over the period of the monitoring. The combined data from 2013 and 2014 indicates that the interval between the return of known individual nesting turtles varies from zero (same night) to 52 days with the single largest number of turtles returning after an interval of 16 to 20 days and 31 to 35 days (Figure 6). A total of 404 nesting turtles were observed in 2013 whilst 671 nests were recorded indicating that not all turtles were observed when they came ashore to nest. 4.2 Measurements Curved carapace length (CCL) varied from 32 to 99cm in length (n=1028). However for the purposes of analysis those below 75cm CCL have been excluded based on a comparison with CCL measurements taken from flatbacks attempting to nest on nearby Crab Island. Here the smallest CCL recorded from 14 nesting seasons over 36 years between 1976 and 2014 was 75.5cm CCL (n= 2615). The difference in minimum size between these two sites is thought to be attributable to recorder error rather than an inherent difference in the size range between the sites. At the same time the actual number of turtles with a CCL below 75cm in the current dataset numbered 20, less than 2% of the total number of turtles measured Page 6 (n=1008). Table 2: Summary statistics for CCL measurements for flatback turtles measured at the Jardine River monitoring site during the 2013 and 2014 monitoring seasons (excluding within season recaptures) Year Number 2013 2014 364 532 Max (cm) 98.5 99.0 Min (cm) 75.5 75.0 Mean (cm) 88.3 88.1 StDev(cm) 3.43 3.10 4.3 Nesting turtle distribution along transect The distribution of turtles recorded along the beach transect was highly uneven (Figure 7). A total of 998 records had accurate location data, of these 938 (94%) were recorded in the first 3.35km (34%) of the 10km transect. Just over half of the transect length contained 994 (>99%) of all the sightings. Page 7 Figure 7: Turtle records with accurate locality data for the 2013 (n=395) and 2014 (n=606) nesting seasons. 4.4 Nesting Over the three monitoring seasons, a total of 2240 nests were recorded along the transect. The highest number of nests was recorded in 2012, with a steep decline in numbers in 2013 and 2014 (Table 3). Table 3: Number of flatback nests recorded on transect over three years of monitoring Year No. of nests Days monitoring 2012 2013 2014 923 671 646 31 57 45 Nests /days of monitoring 30 12 14 As with the nesting turtles, nest distribution along the transect was strongly associated with the north eastern end of the transect with 96% (n=2160) of all nests recorded in the first 5.6km of the 10km transect over the three years. Over the three years of monitoring, nest predation levels have been low with the highest rate observed in 2013, when 8.3% of observed nests were predated. This puts incubation success well above the accepted minimum of 70% required for sustainable nesting success. Predators were a mix of humans, dingo (Canis lupus dingo), goanna (Varanus sp.) and pig (Sus scrofa) (Table 4). Table 4: Predation levels recorded for flatback turtle nests over monitoring period Year 2012 No. of nests 923 No. Predated 13 % predated 1.4 2013 671 56 8.3 2014 646 15 2.3 Predator Human (n=6) Goanna (n=6) Unknown (n=1) Dingo (n=11) Pig (n=28) Unknown (n=17) Human (n=9) Dingo (n=2) Unknown (n=4) Over this same period there has been a targeted feral pig control program in the area which Page 8 has removed over 1100 pigs in the three years between 2012 and 2014 (Table 5). Table 5: Number of feral pigs killed in helicopter control operations Date 2012 2013 2014 2014 2014 Period Total No. killed 9 Dec-12 Dec 6 Dec-12 Dec 26 May-28 May 29 June-30 June 15 Sept-22 Sept Flight hours 337 339 130 159 203 17 16.5 5 7.5 25 No. Pigs/flight hour 19.8 20.5 26.0 21.2 8.1 4.5 Nesting habitat Nesting habitat was recorded for 1327 turtles (671 in 2013 and 646 in 2014) based on the categories shown in Figure 8. The most common location for turtle nesting was high on the beach within the vegetation below dunes (Table 6). Figure 8: Turtle nest habitat categories Table 6: Summary of nesting habitat recorded in 2013 and 2014 Year High tide mark No of nests 2013 2014 79 (12%) 186 (29%) Edge of vegetation No of nests 505 (75%) 334 (51%) Dune system No. of nests 87 (13%) 126 (20%) Temperature loggers were placed in indicator nests at the time of laying. The selection of nests to be monitored as indicator nests were selected at different times throughout the monitoring period. Five indicator nests were established in late July, 3 in early August and two in early September. Temperature varied across nests and across months with a Page 9 minimum temperature of 250C recorded in one nest in July and another in September. A maximum temperature of 33.50C was recorded in one nest during September (Table 7). The most extreme temperature variation was observed in indicator nest 10 where the difference between maximum and minimum temperature was 8.50C. The next greatest variation in nest temperature was a difference of 4.50C between maximum and minimum temperatures in nest 5. Mean temperature between nests also varied across months; as high as three degrees in July and August and four in September. Table 7: Summary of nest temperature data collected in 2014 in indicator nest at the Jardine River monitoring site Site Jardine 1 Jardine 3 Jardine 4 Jardine 5 Jardine 6 Jardine 7 Jardine 8 25.9 0.378 25.0 26.5 337 27.3 0.470 26.5 28.0 337 27.0 0.450 26.0 28.0 337 28.6 0.512 27.5 29.5 337 27.0 0.715 25.5 28.5 1488 28.5 0.573 27.0 29.5 1488 28.2 0.609 27.0 29.5 1488 29.5 0.731 28.0 31.5 1488 28.5 0.692 27.0 30.0 1248 28.5 0.521 27.0 29.0 1248 28.2 0.544 26.5 29.0 1152 27.9 0.596 27.0 29.0 223 29.8 0.258 29.5 30.5 223 29.1 0.262 28.5 29.5 223 31.1 0.392 30.5 32.0 223 29.4 0.374 28.5 30.0 680 29.5 0.281 29.0 30.0 680 29.1 0.404 28.5 30.0 822 Jardine 9 Jardine 10 29.2 0.361 28.0 30.5 870 29.6 0.585 25.0 33.5 1372 July Mean (0C) St Dev (0C) Min (0C) Max (0C) n August Mean (0C) St Dev (0C) Min (0C) Max (0C) n September Mean (0C) St Dev (0C) Min (0C) Max (0C) n October Page 10 Mean (0C) St Dev (0C) Min (0C) Max (0C) n 31.0 0.750 29.5 32.0 676 Figure 9: Nesting flatback turtle in foredune (Image Kerry Trapnell) 4.6 Hatching success One nest was excavated in 2014 to ascertain hatching success (Table 8). Table 8: Clutch size and nesting success recorded in the 2014 monitoring season Clutch Size Hatched Eggs (%) 52 48 (92) Unhatched dead embryos 2 Unhatched undeveloped Unhatched Unknown 1 1 4.7 Satellite tracking 2014 Two flatback turtles fitted with satellite tags on the 12th of September 2014, displayed two very different trajectories (Figure 10). The first, named ‘Cecilia’, moved north on the day of release into Torres Strait and along the coast of Papua New Guinea between Boigu and Saibai island. Information from this tag was received for 60 days before communications were lost. The second animal, ‘Kiku’ remained close to the Jardine River site for more than two weeks and may have nested again during this period before moving south down the west coast of Cape York Peninsula into the south-eastern portion of the Gulf of Carpentaria. Page 11 Communication with this transmitter was lost after 169 days. Figure 10: Track map of satellite tagged flatback turtles tagged in 2014 4.8 Other turtle species recorded Over the course of the monitoring, the nests of five other species of turtle were recorded in low numbers; loggerhead (Caretta caretta), green turtle (Chelonia mydas), leatherback turtle (Dermochelys coriacea), hawksbill (Eretmochelys imbricata) and olive ridley (Lepidochelys olivacea) (Table 9). Table 9: Non flatback turtle nests recorded 2012-2014. Species 2012 2013 2014 1 Loggerhead 1 Green 1 1 Leatherback 2 1 Hawksbill 3 1 2 Olive Ridley 2 2 1 This record is considered likely to be recorder error or misidentification 5 Discussion In 2013 and 2014, a total of 1030 nesting turtles were recorded at the mouth of the Jardine Page 12 River of these, 113 were observed attempting to nest more than once, 22 in 2013 and 91 in 2014. All of these were within season recaptures. One turtle was recorded with a tag scar that indicated it had been banded in a previous year. However, as this individual no longer had a tag it was not possible to determine where or when it had originally been tagged. The interval between recorded sightings of tagged individuals varied between 0 and 52 days with two distinct peaks at 16 to 20 and 31 to 35 days. Differences in the number of nests recorded compared to number of turtles tagged suggests that not every turtle was observed every time it came ashore to nest. This is an artefact of the fact that patrols are not conducted throughout the entire night and travel time along the length of the transect is such that turtles could have time to emerge, lay nests and return to the water before monitoring teams reach them. Most marine turtles lay multiple clutches within a single nesting season at approximately two-week intervals (Limpus et. al., 1993). Data from the present monitoring suggest this is the case for flatbacks at the mouth of the Jardine River, although more data is needed to confirm this. The overall mean CCL of 88.2cm (n=896) recorded in the present study varies little from that recorded for flatbacks on nearby Crab Island of 89.3cm (n=326) (Limpus, 2007) and 88.2cm (n=69) (Sutherland and Sutherland, 2003). However, the range of CCL measurements at these two sites is considerably smaller than that seen in nesting populations in south eastern Queensland. This size difference, along with a number of other factors is indicative of a lack of gene flow between these two breeding populations hence these two populations are considered distinct management units (Limpus, 2007; Fitzsimmons and Limpus, 2014). Measurements from the Jardine River site include a degree of error, given that many of the measurements taken by rangers were rounded to the nearest centimetre. Rangers should be encouraged to take more accurate measurements in future monitoring efforts. Monitoring of turtle activity in 2013 and 2014, and recorded nest numbers between 2012 and 2014, indicate that the coastal area immediately west of the Jardine River remains a significant mainland nesting area for flatback turtles. The vast majority of this nesting activity appears to be confined to the easternmost three to four kilometres of the census beach. Beyond this, activity rapidly decreased along the ten kilometres to the south western end of the surveyed transect beach. The reason for this is unknown although it has been suggested that perched freshwater swamps immediately behind the dunes may be important to successful nesting by seas turtles along the west coast of Cape York. Having the appropriate moisture level in nesting substrates is important to nesting success in sea turtles (Johannes and Rimmer, 1984; Mortimer, 1990; McGehee, 1990). Anecdotal evidence indicates that freshwater soaks, and swamps behind the dunes on western Cape York may be important in maintaining an appropriate moisture level on nesting beaches. The clumped pattern of nesting activity at the mouth of the Jardine may be a reflection of this relationship. The pivotal nest temperature is the temperature that theoretically produces a 50/50 sex ratio in hatchlings. For flatback turtles the suggested pivotal temperature is 29.30c during the 13 Pivotal nest temperatures can have Page middle of the incubation period (Limpus, 2007). significant impacts on sex ratios. At Mon Repos on Queensland’s east coast for example, flatback hatchling sex ratios for the entire breeding season is biased towards females as a result of high nest temperatures (Limpus, 2007). Whether a similar situation is occurring on the northern tip of Cape York is unknown as there is not enough temperature data from the Jardine River monitoring yet to assess this. Future monitoring efforts will also ensure that indicator nests with temperature loggers are spread more broadly across the length of the surveyed beach. This will assist in determining whether temperature differences play any role in nesting site selection. The difference in nest numbers recorded between 2012 and 2013-14 (Table 3) is of some concern, although at this stage it is too early to tell if this is a long term downward trend, methodological problem or cyclic population fluctuation. Only further monitoring will clarify this. As the monitoring methods become clearly defined and standardised it is anticipated that more accurate comparisons will be possible. Nest predation rates were low within the area monitored between 2012 and 2014. This is particularly evident when compared with other areas on the west coast of Cape York. For example 70% of flatback turtle nests were depradated by feral pigs on the Pennefather Beach over a 12 month period from May 2004 to May 2005 (Doherty, 2005). Marine turtle nests – the majority of which were flatbacks – suffered depredation rates as high as 37% at the same locality in 2007 (Whytlaw et. al., 2013). In 2006, a predation rate by feral pigs of 48% was observed in 52 marked nests on the Cape York coast south of Crab Island (unpub. data). Figure 11: Pig shot in 2006 on west coast of Cape York with flat back hatchlings in stomach (Image Lee and Kerlin) An ongoing and effective feral pig control program implemented by the NPARC/Apudthama Page 14 Land and Sea Rangers combined with the ranger presence on the nesting beach during the peak nesting period is almost certainly the reason for the low nest predation rates. Data available indicate that other nest predators, which that are not controlled, such as dingos and goannas are currently only having a minor impact, while the human take of eggs would also appear to be negligible at this stage. The satellite tagging of two females in 2014 was the first for individuals from the Jardine River rookery site. The results so far have supported the view that the turtles in this population forage in the waters of the Gulf Carpentaria and western Torres Strait as far north as coastal Papua New Guinea (Figure 5). Both turtles showed a strong attachment to shallow, inshore coastal areas which is where this carnivorous species accesses the softbodied invertebrates that make up the majority of its diet (Curtis, 2012). While the results from the present tracking have been excellent, this technology has some limitations related to limited battery life, tag design and high costs, which prevent most research budgets (including the current one) from acquiring a large sample size. Therefore, studies quite often have to extrapolate population movement patterns based on a limited number of individuals. If funding became available it would be worthwhile attaching more satellite tags to flatback turtles from this area to gain a better understanding of proportions of the nesting population foraging in the Torres Strait compared to those in the Gulf of Carpentaria. A number of nests belonging to turtle species other than flatbacks were recorded (Table 9). Of these species hawksbill and olive ridleys are known to nest nearby (GHD, 2010; Miller and Limpus, 2012a and 2012b) on Crab Island, while green turtles are known to nest in the Torres Strait (Miller and Limpus, 2012c). There are no records of loggerhead turtles nesting across northern Australia from Lizard Island off eastern Cape York to the Ashmore Reef in northwestern Australia (Limpus 2009a) and without further evidence the record for this species from 2012 is considered to be extremely unlikely and probably resulted from recording error or misidentification. The leatherback nest records are potentially very important. Breeding by this species is thought to no longer occur on the eastern seaboard of Australia with the only confirmed nesting currently known from Australia being a small number of annual nesters on Coburg Peninsula in the Northern Territory. In the past, the species was known to also nest in Arnhem Land on the western edge of the Gulf of Carpentaria as well as in a few localities in southeast Queensland and northern New South Wales (Miller and Limpus, 2012d; Limpus pers. comm.). Recent anecdotal accounts of nesting from Cape York as well as non-nesting records from western Cape York (Limpus, 2009b) means that their presence on the nesting beaches within the monitoring area cannot be dismissed out of hand, however confirmation Page 15 of their presence is needed. Management Summary Monitoring of this important mainland rookery should continue Quantification of monitoring effort should be a priority for 2015 and onwards (i.e. number of days beaches were patrolled over season number of times beaches were checked in a night whether or not turtles were recorded) Recording nesting success should be a priority for 2015 (clutch size, hatching success and predated nests) A more systematic and comprehensive program of nest temperature monitoring should be developed A continuation of the feral pig control should continue to be seen as a priority Academic researchers should be encouraged to examine the relationship between sand moisture levels, nesting activity and the freshwater swamp and wetland areas behind the dunes Every effort should be made to establish if leatherback sea turtles are nesting in this area Page 16 Continuing training to ensure accurate data recording using standard methods References cited Curtis, L. 2012. Flatback turtle Natator depressus (Garman, 1880). In: Curtis, L.K., Dennis, A., McDonald, K.R., Kyne, P.M., and Debus, S.J.S. (Eds.). Queensland’s Threatened Animals. CSIRO Publishing, pp. 197–-198. Doherty, J. 2005. Ecological impact assessment of feral pig predation in marine turtle breeding habitat on the west coast of Cape York. Unpublished thesis prepared for Charles Darwin University, Darwin. 71pp. Fitzsimmons, N.N. and Limpus, C.J. 2014. Marine turtle genetic stocks of the Indo-Pacific: identifying boundaries and knowledge gaps. Indian Ocean Newsletter No 20: 2-18. GHD, R. 2010. Queensland NRM Report for Caring for our Country. Overview of marine turtle nesting on western Cape York. Unpublished report prepared for Queensland Government, Brisbane. 76pp. Johannes, R.E. and Rimmer, D.W. 1984. Some distinguishing characteristics of nesting beaches of the green turtle Chelonia mydas on North West Cape Peninsula, Western Australia. Marine Biology 83: 149-154. Limpus, C.J. 2007. A biological review of Australian marine turtles. 5. Flatback turtle, Natator depressus (Garman). Unpublished report prepared for Environmental Protection Agency, Brisbane. 52pp. Limpus, C.J. 2009a. A biological review of Australian marine turtles. 1. Loggerhead turtle, Caretta caretta. Linnnaeus 1758. Unpublished report prepared for Environmental Protection Agency Brisbane.70pp. Limpus 2009b. A biological review of Australian marine turtles. 6. Leatherback turtle, Dermochelys coriacea (Vandelli).Unpublished report prepared for Environmental Protection Agency Brisbane.26pp. Limpus, C.J., Couper, P.J. and Couper, K.L.D. 1993. Crab Island revisited: reassessment of the world’s largest flatback turtle rookery after twelve years. Memoirs of the Queensland Museum 33 (1): 277-289. Miller, J. and Limpus, C. 2012a. Hawksbill turtle Eretmochelys imbricata (Linnaeus, 1758). In: Curtis, L.K., Dennis, A., McDonald, K.R., Kyne, P.M., and Debus, S.J.S. (Eds.). Queensland’s Threatened Animals. CSIRO Publishing, pp. 193–-194. Miller, J. and Limpus, C. 2012b. Olive Ridley turtle Lepidochelys olivacea (Eschscholtz, 1829). In: Curtis, L.K., Dennis, A., McDonald, K.R., Kyne, P.M., and Debus, S.J.S. (Eds.). Queensland’s Page 17 Threatened Animals. CSIRO Publishing, pp. 195–-196. Miller, J. and Limpus, C. 2012c. Green turtle Chelonia mydas (Linnaeus. 1758). In: Curtis, L.K., Dennis, A., McDonald, K.R., Kyne, P.M., and Debus, S.J.S. (Eds.). Queensland’s Threatened Animals. CSIRO Publishing, pp. 189-190. Miller, J. and Limpus, C. 2012d. Leatherback turtle Dermochelys coriacea (Vandelli, 1761). In: Curtis, L.K., Dennis, A., McDonald, K.R., Kyne, P.M., and Debus, S.J.S. (Eds.). Queensland’s Threatened Animals. CSIRO Publishing, pp. 191-192.McGehee, M.A. 1990. Effects of moisture on eggs and hatchlings of loggerhead turtles (Caretta caretta). Herpetologica 3: 251-258. Mortimer, J.A. 1990. The influence of beach sand characteristics on the nesting behaviour and clutch survival of green turtles (Chelonia mydas). Copeia 3: 802-817. Sutherland, R.W and Sutherland, E.G. 2003. Status of the flatback turtle (Natator depressus) rookery on Crab Island, Australia with notes on predation by crocodiles. Chelonian Conservation and Biology 4: 612-619. Whytlaw, P.A., Edwards, W. and Congdon, B. 2013. Marine turtle depredation by feral pigs (Sus scrofa) on the Western Cape York Peninsula, Australia: implications for management. Page 18 Wildlife Research 40: 377-384.