We were picked up by the ‘Tropic Paradise’ on their way north back to Seisia and arrived back in civilisation late Sunday afternoon. We were exhausted but sad to leave Crab Island. It went so quick. On the boat we shared our stories with a group of New Zealanders and Americans who were eager to find out about our adventure. After only having each other to talk to for the past month, it was overwhelming conversing with so many new people. However, I savoured my first beer which an Aucklander gave me! After arriving back at the wharf we spent our time in Seisia cleaning gear and organising for our trip back south down Cape York. The noise of the ‘crowds’ in the camp ground overwhelmed us and we dreamed of being back on Crab. We can’t wait to return in another couple of weeks…
Sunday, September 28, 2008
On last year’s field trip we had been looking for clear evidence of crocodiles attacking adult sea turtles. It came in the form of finding a dead flatback on the sand flats of the north west corner of the island about an hour before we were to leave the island. This year we were looking for more evidence. In a bizarre coincidence, the first clear sign we found was of the dead turtle in the previous post - we found the turtle in exactly the same spot where we found the one last year and we found it about an hour before we left the island!
(Warning: not for the light hearted.)
Last night on Crab Island a crocodile attack occurred. We discovered the aftermath this morning on the northern beach. The attack was brutal and a reminder of the power of a saltwater crocodile. The poor adult female flatback had most likely nested and was returning to the sea before being grabbed by a crocodile in the shallow water. The 200lb turtle’s shell was split in 2. Her carapace had huge crocodile puncture marks and had been crushed. All her limbs and her head were severed. It was upsetting to see but clear evidence of crocodiles predating on adult sea turtle. This is one of the only places in the world where crocodiles feed on sea turtles on a regular basis – or so we are discovering.
In fact this is not the first crocodile attack we have witnessed on this trip. We have found clear evidence of at least 6 other turtles being attacked. Three of these were identified by tracks and blood on the sand. Generally the adult females were returning to the water and at the same time crocodile tracks appear from the surf and intersect the turtle track. At this point there are scuffle marks and blood in the sand, and then no turtle marks (indicating the crocodile is carrying the turtle), drag marks or retreating turtle tracks (indicating an unsuccessful attack, though the crocodile may have attacked again in the water).
Another turtle we found had had her head crushed, and clear signs of crocodile teeth marks, but still nested ok. Another 2 we found with a piece of their shell dangling and fresh blood. A large percentage of turtles which nest show signs of older attacks, whether by sharks or crocodiles. Many girls are missing flippers, parts of their shells and have bite marks. Many still nest despite the fact that they don’t have 2 rear flippers to dig an egg chamber. Many still drag themselves out of the water even though they are missing a front flipper. They are tough girls and it is amazing the injuries they can survive.
*tracks and blood showing a crocodile attack on an adult sea turtle (crocdile track is in front of Kelsey)
This morning when we came around the northern corner of Crab Island after finishing our track count we startled 2 Jabirus. They are huge storks with dark iridescent necks, and white and black feathers on their body. Jabirus stand up to 115cm. They seemed very nervous upon our presence and flew off to the mud flats. We were able to watch these amazing birds through our binoculars. It was so neat to see them fly because they fly with their neck extended (rather than tucked in like a heron would). We have seen them fly over in the distance and their large tracks on the beach but this was the first close sighting of them.
Last night Brett was walking up the dune when all of a sudden I saw him fly through the air. His leap was just in time to save a hatchling’s life. The innocent hatchling had been making his way down the beach to the water when a mean crab grabbed him and proceeded to drag him down its burrow. Lucky for the hatchling Brett was there to make the brave rescue.
This hasn’t been the only time we have seen crabs viciously grab hatchlings. There have been quite a few cases when unfortunately we weren’t able to help the hatchlings. With saying that there were a couple other times when Brett was able to pull the hatchling out of a crab burrow.
One of the major forms of marine debris we find on the beaches of Crab island are fishing nets – very large nets designed to catch lots and lots of fish and other marine life. I have mentioned ‘ghost nets’ a few times in this blog but I thought that the subject really needed it’s own post. They haunt us each time we go onto the beaches here. They are called ghost nets for the reason that they are lost or set free and drift the ocean catching score of marine life as it goes. These nets can be mile and miles long. Eventually they will get washed up on the beach. Many nets will have carcasses of marine life, such as sea turtles, dolphins, crabs and fish. But the damage hasn’t stopped once they land on a beach. The next big storm will wash them back off the beach and send them drifting the oceans once again. For example, earlier this year a cyclone hit the west coast of Cape York here and sent hundreds of nets back into the ocean. A few weeks later many nets were washed back, along with hundreds of dead turtles.
There is not a part of the beach on Crab Island where you can stand and not be looking at a ghost net. Some are on the surface of the sand, others wrapped around logs and trees, whilst many are buried with only a small part of them sticking out. Most of these nets are from illegal fishing sources. Most nets can be identified to sourced by their design and the technique in tying the knots.
The scale of the problem is enormous and efforts are underway to start to mitigate the impacts. The local Aboriginal Rangers are doing a great job in removing and burning nets as part of the Gulf of Carpenteria Ghost Net Program. But the scale of the job is massive and more needs to be done. In the meantime, many thousands of sea turtles are still being caught in these nets.
You would think that being so far away from any form of civilisation on a remote, untouched part of the Cape York wilderness that we would be free from any human influence. It’s far from the truth. The beach is littered with beach debris (ie. rubbish) originating from illegal fishing vessels, the commercial fishing industry, cargo shipping and from nearby countries such as Indonesia. Some of the things which land on the beach are just mind boggling – kids toys, refrigerators and thousands upon thousands of thongs (or ‘flip flops’). Some of the more common items are water bottles, glass bottles, gas cylinders, floats, rope and net. This is common on remote beaches all over Cape York and the northern Great Barrier Reef.
We have had to untangle a number of nesting flatbacks from ropes and nets which they have been caught in whilst making their way up or down the beach. One flatback had been caught in rope which was wrapped around her neck and strangling her. We also found hatchlings caught in a nest and unable to emerge because of rubbish which had been accidentally pushed into the nest by the nesting mother.
We undertook a beach debris survey on a 250m stretch of beach. A lot of products such as deodorant bottles, glass bottles, rope, net etc we can identify origin. We sourced 90% of the rubbish originating from Indonesian sources – illegal fishing vessels and possibly areas like Irian Jaya. The number of plastic water bottles is staggering, and is making us think twice about buying them anymore.
The amount of rubbish in our oceans is nothing short of a disgrace. To come to a remote location such as Crab Island and to see so much man made rubbish, and to see the effects first hand, makes you realise that the impact of humans is far reaching.
Marine debris in Australia is listed as one of the main threats to the recovery of sea turtle populations in the ‘Recovery Plan for Marine Turtles in Australia’ [www.deh.gov.au/coasts/publications/turtle-recovery/index.html]
We had our hottest day on Crab Island yesterday – a sizzling 52oC (126oC)!! At about 12.30pm we looked out to sea, only to be surprised to see dozens of dark shapes swimming back and forth, parallel to the shore. Flatbacks were surveying the beaches, ready to nest, lifting their heads out of the water to look for a suitable nesting location. Shortly after they began to emerge and make their way up the beach to nest. They continued on all afternoon coming and going. By the end we had counted 461 turtles between lunch time and midnight.
No other species of sea turtle would even think of nesting in this kind of heat. In fact daytime nesting is quite a rare event in the world. Raine Island for example, which is on a similar latitude as Crab on the eastern side of Cape York on the Great Barrier Reef only about 150km away, sees many green turtles perish during the nesting period when they leave their run too late in the morning in returning to the water and simply ‘boil’ in the hot sun. So it is phenomenal to think that flatbacks can go through the whole nesting process, exerting huge amounts of energy, in that kind of heat.
Walking down the dunes from our camp to check on some turtles below Billy’s Bluff we came across yet another snake to add to the increasing list on Crab Island. This guy is a Slaty Grey who was about 6ft in length – another new record. We like to think that it is an island of friendly snakes, as we are yet to find a venomous one as yet…
Wednesday, September 24, 2008
This morning the waters were calm, making it easy for a few boats to cruise on down to Crab Island from the island and mainland communities. As we came around the corner up north, while doing our track count, we saw a boat land. We went around to say “hello” to three friendly Islanders from Seisia. They had come out to Crab Island to collect sea turtle eggs. They probe the sand with spears around freshly laid nests to find the eggs. They said they were going to harvest enough to fill a plastic trash can they brought along. In addition, on the boat ride they were searching for Green Sea Turtles in the waters to hunt (they taste the best, we have been told). Green turtles are currently congregating in the Torres Strait to mate, before heading to their nesting beaches to lay. We were informed that one adult turtle would feed about 4 families of 6 and during this time they catch around one each week.
Also, there were a few other boats on the adjacent mainland that came from Thursday Island and we are expecting them to come across to Crab later today. In the time we have been on the island we have seen and met a number of groups of Aboriginals and Islanders who have arrived in search of freshly laid turtle eggs, and the odd adult, along with some others offshore that hunt from the bows of their boats with spears and by jumping. I don’t think I would be able to jump off a boat into the water to catch a turtle knowing there are plenty of crocs and sharks about. All in all they have been friendly towards us and we hope to keep good relations with them.
On Friday the 5th of September at 9pm we tagged 2 girls who were nesting side by side, just a little south of our camp. They were turtles K96151 and K96152 and were both nesting just below the slope of the dune. A couple of nights ago on Monday 22nd of September at 9pm we came across 2 turtles nesting next to each other. Both had tags. Kelsey read one and I read the other, both singing out in sequence “151” and “152”. Both girls had nested side by side again, exactly 17 days since we had tagged them originally nesting within a few metres of each other!! This time they had nested 130 metres to the south of their original location. Kelsey thinks they are either sisters or best friends and follow each other everywhere! It is either a big coincidence or there is something more to it…. Hmmm?
Then take last week. On one of the nights we were tagging turtles we noticed that a large majority of flatbacks on that particular night had white pigment across the backs of their flippers. Every other night we have had the odd one with white pigment, but this night most turtles had similar markings. Coincidence or is there something more to it….hmmmm?
Tuesday, September 23, 2008
We are excited.
In previous posts during the first part of this trip you would have noted that we were frantically tagging turtles in a hope to get ‘tag returns’ when they came back to nest again after a couple of weeks. Flatbacks may nest 2 or 3 times in a season and the time in between nesting is known as the ‘renesting interval’. This is currently unknown on Crab Island – no one has ever identified the renesting interval for these particular turtles, which is important for identifying reproductive output. Last Thursday we were excited to pick up our first tag return – turtle number K96033, the 33rd turtle we had tagged back on about the 3rd day. Since then we have identified another 80 turtles which we had tagged previously on this trip!! Every night we go out now we are picking up more and more. On average, turtles are coming back to renest after 16 days.
We have also identified close to 30 turtles which have been tagged in previous seasons. This is important as it will help us identify ‘remigration intervals’ for the first time – another aspect currently unknown for Crab Island. We think that they will have a relatively short turn around of between 18 months to 2 years. Green turtles usually remigrate after 5 years and often as much as 7!
We are now focussed on identifying reproductive output by counting eggs and identifying hatching success of clutches. We are also prioritising getting Dna samples of turtles and collecting morphometric data of hatchlings.
Last week we finished up most of our tagging run and have tagged over 650 turtles!! This should provide us with a wealth of data into the future. We have very sore hands from writing and tagging! But we are not complaining…
So far while exploring inland on the island we have found 3 sea turtles skeletons. In addition, we saw tracks leading far into the island, behind our camp. These poor girls must have got disorientated while trying to nest or returning from nesting.
…sitting at the dining room table enjoying lunch you hear something fall on the ground behind you. Kelsey, on the opposite side of the table and not prepared to rush the mouthful of food she is enjoying, casually states after a few moments “Brett, a snake just fell out the tree – it’s right behind you”.
“ahh… thanks?!” as I enjoyed the last of my sweet chilli chuna.
The snake which landed in our dining room was a northern tree snake – another new record for Crab Island. They are either very clumsy on Crab Island, or this particular guy likes to jump out of trees, as a snake ‘fell’ out of the same tree and nearly landed on Sam Prisk back on our May trip!
Our ‘drive way’ has become a popular nesting location. Without fail, each night as we arrive home we either drop into a new ‘body pit’ or become bogged in the soft sand which has been thrown by nesting flatbacks! We normally have to leave the quad bike where it gets bogged and then drag our tired bodies up the steep dune to get to bed! The next morning we have to clear the driveway of soft sand with our little shovel. We desperately need one of those big snow shovels sent from Connecticut or Ontario!!!
Monday, September 22, 2008
When working on the beach in one place for more than a couple minutes turtles swarm from everywhere. It is like we are turtle magnets.
For example, last night we stopped at a female who was laying eggs. Brett stuck his hand in under her and collected the eggs to be weighed and measured. Once all the eggs were taken up and lined up to count, the mother began to hind flipper fill to cover where she laid. At this stage we needed to move her so we could safely return the eggs to the egg chamber she dug. It was a struggle (at least for me) to try and lift her; but together we were able to move the over 200 lb female away from her nest. Then the turtle attraction began…as we were counting the eggs she laid, hatchlings appeared. We looked around to find them emerging under the mother who we had just moved. I jumped up to save them from being crushed by the female’s large determined flippers. I saved them and tried to continue with our collection of data. Brett cleaned off and measured the maximum and minimum width of the eggs while I weighed them. Which sounds easy but when I was trying to weigh an egg on the scale (which is annoyingly wind sensitive), the 50-60 hatchlings wanted to climb all over the scale too. Then the mother decided that instead of returning to the water she wanted to come towards where we were working. First she tried to run over her nest which was uncovered since we were taking measurements of her eggs…Brett saved them by throwing sand over just in time and turning her towards the water. Phew, she was heading to the water and we could get back to work. Then, again, she came crawling towards us…what the heck! We tried to turn off our lights thinking that was distracting her, since the moon was not out yet to lead her back to the shiny water. This did not work and she was determined. After running over our gear Brett was able to move her and she seemed to be headed the other way. So back to work we went…then all of a sudden she was nudging into my back. Come on, we are trying to work here Mrs. Turtle, can’t you see that? In addition to her, two other adult females were headed in our direction…thankfully they turned before coming too close. We finally finished weighing and measuring the eggs somehow and returned them to the nest and completely covered them to insure their safety. Next we had to weigh and measure the hatchlings. It was far too frustrating having turtles everywhere while trying to collect the data. We couldn’t stop them from being attracted to us. It was like they wanted us to tag, weigh, and/or measure them. So we picked up 10 hatchlings put them in my bag and moved down the beach. In order to hide from those turtles who were drawn to us, we turned our spot lights off for a few minutes. When we thought we had lost them we turned on our lights and finished the measurements of the hatchlings. I love having so many turtles around but it was a challenge to do research when we were like magnets pulling in all that were in that area.
There are many times on Crab Island in between the hard work and heat when you stop, take a deep breath and soak up the place and moment. A couple of nights ago was one of those moments. It was a full moon, the beach was bright and had the bluish hue that only a moon, unaffected by artificial lights, can shine. It was still, with only the sounds of gently breaking waves and the odd shore bird, and we were on the beach towards the south of the island. The beach stretched on into the far distance, before disappearing into the ocean as the island bent towards the east, the water reflecting the glow of the moon. Standing there and looking south we could see small ‘explosions’ of sand, rising to a couple of metres, scattered all over the beach and as far as we could see. Within the ‘craters’ of these explosions were glowing dome shapes, the shells of sea turtles reflecting the moonlight. Within the waters, beyond the surf break, within the surf and on the waters edge, sea turtle’s shells glowed, still wet, as they emerged to nest. Turtles could be seen making their way up the beaches, stretching into the distance, their backs still wet from the ocean and reflecting the blue moon brightly. The sounds of sand being flung like a beating rhythm and the deep breaths of turtles as they struggled to drag their heavy bodies up the beach now dominated. It was a moment to savour, one of many….
Baz, the cane toad has been sighted in and around our camp multiple times. For those who have never heard of cane toads, they are an introduced species to Australia. They are poisonous and are killing off many native animals, making them an unwanted pest. It is a shock having them on the island…they seem to be invading everywhere here in the north. We aren’t sure how they got to the island but maybe they drifted on a log or a bird carried their eggs from the mainland. Here on the island they are a threat to the snakes and birds which eat them.
We find many interesting thing on the beach. Last night whilst out on the beaches we were surprised to come across a water python slowly wandering through the nests of turtles. We know 1 was recorded on Crab Island 17 years ago, but this is the first since then.
It would be easy to wonder how the flatback sea turtle is a threatened species seeing we have counted over 4500 turtles since our arrival. However, while it would be great to say the species is stable, the reality is there are a number of factors which make them vulnerable to extinction. The numbers we are seeing are probably only a proportion of what was a much wider and larger nesting population. Crab Island is possibly a remnant of what was once a population which nested right down the west coast of Cape York.
The fact is Crab Island supports the majority of nesting females for the entire species and seeing so many comes as no surprise. We are at the peak of the nesting season, seeing the majority of females. To put things into perspective, when you compare Crab Island to other major Flatback rookeries, such as those in central Queensland, the Northern Territory and Western Australia, it is clear that Crab is the hotspot. These other rookeries support several hundred nesting flatbacks each year, with a combined total of several thousand. Crab on the other hand can support several hundred each night, and may have a nesting population of between 10,000-15,000 females.
What’s the fuss you may say? Well, while we know very little about flatback sea turtles, we do know they have suffered severely from various impacts in recent decades. For starters, the three decades from the mid 70’s saw intensive trawling effort in northern Australia and the Gulf of Carpentaria. This tripled in intensity by the mid 90’s before being regulated. During this period tens of thousands of sea turtles were trawled up each year and the majority of these were flatback sea turtles. The impact of this was not immediate, and we still probably haven’t seen the result of these activities. The reason being was that most of the turtles trawled were sub-adult turtles. This is important as sea turtles are a long lived species (they may live over 100 years, but no one has studied them long enough to know), and they may not mature until they are 35–50 years old. Therefore, a generation of turtles may have been severely depleted and we will not see that impact until at least next decade.
On top of this, feral pigs are destroying close to 100% of nests on the mainland. This means that no eggs are hatching and no turtles are being recruited back to the population. It is likely that turtles which lay on Crab, also lay on the adjacent mainland and make up one large breeding unit. No eggs hatching is bad enough. What makes this worse is that the evidence we have collected to date suggests that mostly females are born on the mainland and mostly males on Crab Island (sex of hatchlings is determined by sand temperature). Females are the most important aspect of the survival of any species – no females being recruited to the population is not a good thing.
Once again, the impact of feral pig predation on nests will not be seen for a couple of decades. All of a sudden there are several generations of turtles which will not be breeding. They will struggle, but they have survived since before the dinosaurs, through ice ages, etc, so they are a pretty tough species. They may survive and continue on, unless they were pushed to the edge by something major…
Climate Change - A threat in itself to the existence of sea turtles, and could certainly be the nail in the coffin when you look at the cumulative impacts on flatbacks. Sea turtles will be one of the first species impacted by climate change – they are very dependent on a stable temperature. For example, the sex of hatchlings is determined by the temperature of the nest during incubation. There is a pivotal temperature during incubation (around 27oC/80oF) – hotter than this it will produce females, colder and you get a male. But there is a small window which results in mortality – sand temperatures above 32oC/90oF or below 24oC/75oF will result in mortality. The reason that Crab Island supports so many nesting turtles is that the sand provides the right and stable temperature range for incubation. It’s not as simple as moving to a new nesting beach.
For a small island such as Crab, where a lot of turtles lay their eggs just above the high tide mark, sea level rise could also result in flooding of nests and high mortalities. It is unknown what higher sea temperatures will do to food resources and traditional feeding grounds.
Other factors which require investigating are some reports of flatbacks turning up in markets in Irian Jaya (Indonesia). Crab Island’s close proximity to the indigenous communities of Bamaga and Thursday Island also means that the traditional harvest of turtles and eggs remains unmonitored. The island is much more accessible these days with the use of outboard motors, rather than the traditional dug out canoes.
In addition, while the trawling activities in Australia’s northern waters have now been regulated with the introduction of mandatory ‘Turtle Exclusion Devices’ (TEDs), there is increasing illegal fishing in these waters. Having overfished their own waters, and with the rich abundance of fish stocks in Australian waters, it is tempting for illegal Indonesian fishing boats to plow the same waters in which flatbacks occur. Indeed, thousands of illegal fishing vessels enter these waters each year, overwhelming the customs vessels which patrol them. The catch of flatbacks remains unmonitored but is most likely high.
The other factor associated with illegal foreign fishing vessels is their habit of discarding or losing large fishing nets, sometimes miles long. These are known as ‘ghost nets’ and their impact should not be underestimated. Indeed on Crab Island there is a washed up ghost net at least every 100ft –and those are the ones you can see which have not been buried. These nets drift the oceans catching countless numbers of sea turtles and other marine life before being washed ashore. But the reason they are known as ghost nets is that when a storm hits they are normally washed back off the beaches and back into the oceans to catch more marine life.
The cumulative impact of these threats may be sudden and irreversible. Add to this other factors such as increased boat strike, increased tourism, pollution (we have identified for the first time fibropapilloma on flatbacks – a tumorous growth associated with poor water quality) and the fact that Crab Island remains unprotected. Simply, this means the flatback sea turtle is far from being safe and secure.
These are some of the main reasons why the flatback is listed as a threatened species. But all is not gloomy and we, personally, remain optimistic – the flatback’s range is mostly contained within Australian waters, unlike most other sea turtle species who are found globally and whose range may cross many international borders. This presents an opportunity for effective protection. Crab Island is still a remote location and this in itself provides a level of protection. However, Crab Island is too important a resource to not have any formal protective status over it. It is still open to interests such as mining or major tourism. The opportunity exists to secure the island for prosperity and to start to mitigate the major threats highlighted above throughout their range. But this has to start immediately, conservation strategies are long overdue.
The purpose of this study is to start to get a good understanding of the population dynamics of the breeding cohort of Crab Island’s flatbacks – are they decreasing, stable or increasing? At the moment it is unknown. Only a long term monitoring study will determine this, and conservation strategies can be better informed which will assist in halting any downward trends.
Thursday, September 18, 2008
In the last week we have had some new neighbours move in and start building next door. They are a pair of sunbirds which have been frantically building a nest next to our tent. They both are a beautiful bright yellow and the male has the most amazing iridescent blue on his throat. They are a bird of tropical northern Australia, and to see sunbirds again is a great reminder of where we are.
The nest is a hanging, pendant style made of feathers, leaves, twigs, cobwebs, and bark. They must have the best view on the island having built their nest right on the headland overlooking the water! It has been great watching them busily build. They are near completion and ready for some spring lovin'!!
…and then it began to happen. Within moments we were surrounded by nesting turtles, all starting to throw sand everywhere. Then the 2 girls we had been working on had decided they had finished nesting and were returning to the water – but both wanted to go the long way, straight over all our gear and the eggs we had laid out on the sand! In a frantic display of the ‘turtle 2 step’ we attempted to divert them away from destroying their own eggs (which can be fairly difficult with determined 200lb turtles!)! Then, in the midst of the chaos, dozens of hatchlings started emerging out of the darkness – a new clutch had erupted and all were attracted to our lights! So there we were, trying to divert 2 large turtles, and also trying to save dozens of hatchlings from getting squashed by the adult females! On top of all that, beach stone curlews and rufous night herons arrived ready to feast on the hatchlings!! What to do, who to save? – the big decisions! Talk about mayhem! But somehow we managed to stop any major disasters – turtles went back down the beach, hatchlings made it safely to the water, birds left disappointed and all eggs remained safe. All was quiet again. Kelsey and I were left looking at each other and both repeating the words “what was that?”…
In the past few days we have come upon a few unusual Flatback hatchlings. As you know from previous pictures of Flatback hatchlings, they are a grey color with darker blackish lines defining their scoots.
Well the first unique hatchling was a tan/olive color and very light compared with its siblings who can from the same nest.
Next, we found a whole clutch of Flatback hatchlings that were all a brownish color. It was very interesting after seeing so many looking the same to come upon those who were slightly different.
Last night we were measuring and weighing a clutch of Flatback hatchlings, when out of the dark scurried a little baby onto my lap. Where he came from I am not quite sure. I noticed he looked small so I put him in my pocket for safe keeping until we finished measuring and weighing the other clutch. So far all the Flatback hatchlings have been about 60mm in length (carapace/shell length) and weigh about 40g. I thought it would be neat to get the measurements of this little hatchling; who I named Teeny Tiny. I found that he weighed 29g and was a mere 51mm in length. I could have kept him, he was so little and cute!
The one noticeable factor during this trip has been the number of crocodiles on the island. Most trips along the beach we count at least 25 crocodiles. During low tide they tend to sit out wider on the sand bars. They range in size from around 1.5m (5ft) up to 4.5m (15ft). Some days the water is crystal clear and it is amazing watching them as they sit on the bottom ‘hiding’ or swimming away underwater and popping up out wider keeping a watchful eye. Either way, they are still very scared of us and will be in the water long before we are close to them.
The predation of sea turtles by crocodiles has been little recorded in the world. Crocodiles feeding on hatchlings has rarely, if ever, been documented. While we suspected that it was happening on Crab from our first visits, we still needed the evidence. So in the last few weeks we have been collecting some good data which shows that saltwater crocodiles are a major predator of hatchlings on Crab Island. Each morning we record hatchling emergences and we also record crocodile tracks which have been actively chasing hatchlings on the beach. Each night we will see crocodiles on the beach, and each morning we will find tracks showing crocodiles moving across the beach. They tend to occur where there have been a large number of hatchling emergences. How the crocodiles know where these dense areas are each night we do not know – it could be that they rely on the rufous night herons and pelicans to give away locations, or it could be that they can sense the march of the hatchlings down the beach.
When we are on the beaches at night we tend to know when crocodiles are feeding on a clutch of hatchlings. From the distance with our spotlight we can see crocodiles spread across the beach getting the hatchlings as they emerge, and others waiting at the waters edge.
It has been difficult to get any good footage, however we have been able to witness crocodiles actually eating hatchlings on a couple of occasions. To get good photos or video we really need night vision – the spotlight tends to scare the crocodiles, whilst also attracting the hatchlings back towards the light. Even so, we have been able to see a crocodile grab a hatchling on the waters edge and another actually feeding on one – the crocodile will either wander after or sit and wait for the hatchling, and then turn its head on its side and pick it up with it’s teeth, before tilting it’s head in the air and manoeuvring the hatchling down its throat before swallowing.
The photo in this post shows a crocodile about to eat a hatchling at the waters edge. While the photo is very grainy (we took it from a distance), it is probably the first ever photo of such an event.
We are still being very crocodile savvy and still never get complacent. We enjoy seeing the crocs during the day and at night – we now recognise individuals and have names for a couple, including ‘Charlie’ and ‘Obey’, which we will write more about later….
Tuesday, September 16, 2008
Brett began to dig up a clutch which we saw had emerged the previous night so that he could measure the success. As he began there were a couple live hatchlings then more and more until we reached 20. Therefore, some of the hatchlings from this clutch emerged last night, while these ones must have been waiting for the next night when the temperature would drop again. In order to get more data we decided to take them back to measure and weigh them. All we had with us was our backpack so we emptied it and filled it with hatchlings. They were all flapping and excited to be out of their dark nest of sand. Back at camp I measured and weighed the hatchlings while Brett recorded. I love working with the hatchlings, it is such a delight. After, we finished obtaining the information we needed we took the hatchlings back to the edge of the water. On your marks, get set, go!...As I put them on the ground it was a race to the water. Some weren’t so sure at first and needed time to get used to the surroundings, while others made a dash to the water. Luckily we were there because as soon as the local birds saw them scurrying around, they flew down to see if they could get a snack. First a big whistling kite flew over. It got so close I thought he was going to fly down and take them out of my hand. We were able to keep the birds away while the hatchlings were on the beach. Unfortunately, once the hatchlings were in the water we couldn’t keep the terns from taking 3 of them. Life and death is another cycle here on Crab…it can be sad but you can see that nature has its own way. I feel so fortunate to be able to work with the hatchlings and female turtles - I really see the whole life cycle and it is breathtakingly beautiful.
We have got the local barramundi worked out and can now almost guarantee a couple each fishing trip! It is a matter of being at our ‘secret spot’ at the right time – but we aren’t going to give that away now are we?? We learnt the right time through trial and error – we knew it was associated with an incoming tide - went a little earlier and after hundreds of casts with our squidgy lures, not even a bite. But we persisted. … and then we realised there was a pivotal point during the tide, a time when the barramundi could either get over a sand bar as the tide was rising and allow them to get upstream or simply just come on the bite. Either way it is like flicking a switch and each time we go we can get a barramundi on just about every single cast (except the ones that land in trees from errant casts!). The challenge is landing the fish as there are snags everywhere…. But we are learning fast and becoming great fisherpeople as a result…! J
Monday, September 15, 2008
Yesterday reached a record high here on Crab. It was 115oF or 46oC and boy we could feel it. The wind died down so we had no relief until the sun went down. We tried to stay in the shade when we could in order to stay cooler. Today went down to about 90oF or 32oC with a nice wind…but on average it has been over 100oF or 38oC. The heat hasn’t really been humid so it isn’t too hard to handle. In fact I like it compared to the colder temperatures I have been told about from my family back in Connecticut. Brett has been enjoying it too since he left the cooler weather down in Tamworth as well. For just the beginning of spring it has been quite hot though, I can’t imagine the middle of summer as it gets more hot and humid.
Saturday, September 13, 2008
Last night we were collecting data from turtles up in the dunes on the north of the island. We were just about to check on another turtle when we came across this nice specimen of a snake. Well, we couldn’t tag a turtle with that right next to us, so we moved the little fella out of the way!
…well I agree, he may not have been so little - in fact at least 10ft! The exciting thing is it is an Amethyst Python and this is the first one to ever be recorded on Crab Island (we did find a skin back in May, but this definitely confirms it!).
When you have a 10ft snake in your hand, 200lb sea turtles nesting all around you and a few sets of crocodile eyes reflecting back at you from the waters edge, all on a brightly lit beach under a near full moon, …you know you are in a pretty wild place!
When you think you have the turtles worked out on Crab Island, you are normally brought back to a sudden realisation that….well…. it’s more complicated than it seems. The cues that initiate nesting are fascinating, but unclear. Last night was no exception with what has been the biggest nesting night during the trip – and it came as a big surprise! Story goes… We were expecting some nesting just before dark, so we went out early and headed south. Normally we see a fair bit of nesting in this area. With a midnight high tide we expected to see turtles nesting on the build up right through to this time. However there were hardly any turtles and we headed north, driving long distances between the odd turtle nest. Thinking that the night had been a bit of a dud, it wasn’t until we got to the extreme north of the island that we realised that, in fact, it had been one of the most amazing nesting events since we have arrived…. And we had missed it all!!! There were turtle tracks criss-crossing one another as far as we could see… 700m with not one piece of clean sand, all churned up from turtles crossing the beach. The odd turtle was still up, but it seemed the turtles had nested just before dark. It also seemed they had all come up together and all concentrated in the one area. At least 350 turtles nesting in ther one spot! Bugger me! But how amazing! have a close look at the video and photo in this post - while it doesn't do the spectacle any justice, it gives you an idea of the density we are seeing..
We have made our camp into a comfortable little home. I will start in the main living/dining room area. Here I have added some decorations…Tibetan prayer flags (thanks to Nancy) hung through the center of the room, on our dining room table I put shells filled with little treasures I have found, a candle, a small tree, and the entrance is lined with coconut shells/husks. We have a small radio for news and music when we can pick up the station. On one side of our main area we have shelves made from bamboo and net to hold our dishes, fresh fruit and veg, and our canned food on the bottom. Next to this shelf are large containers of water and a cooler/eskie to keep things cool for the first few days when there is ice (we don’t have a refrigerator). On the other side of the room is our cooking area. This area contains our stove, condiments, seasonings, some small net shelves for storage, and bins below to keep our food safe from bugs. Also, under this table buried in the ground are potatoes, sweet potatoes, and a pumpkin to keep them cool to last longer. The tables throughout this area are made from the metal pieces from the bottom of our boat. We stacked the metal pieces on netting, bins, bamboo, or wood in order to make the tables sturdy.
Next we will move on to the bedroom. Our bedroom is a tent. The tent is big enough for a full size blow up mattress with space on each side for us to put clothes, etc. There are two large entrances, a front and back door. In addition, the two other sides are large windows. When both the doors and windows are open a nice breeze comes through to cool it down...our air conditioner. The best part is the view from bed. We can see the water and beach from inside the tent. It is so calming to fall asleep or relax while listening to the waves roll in and the birds sing.
A few other additions to our camp…First we have a shower area which contains a solar shower, towel rack, and shelf. Next we have a porch out front on top of the dune; which is called “Billy’s Bluff”. We have an internet/phone booth up on the high dune as well. Here is where we have an aerial attached to long pieces of bamboo then stuck in a tree in order to pick up reception. In addition, we have a hammock hung up in the shade with a beautiful view. Furthermore, to the back of our main area is another high dune which is great for charging things using the solar panel, doing yoga, or enjoying the gorgeous place that we live in. Lastly, we have a garage where we keep the quads in the shade and store fuel.
I hope you enjoyed the virtual tour of our humble abode!