Christmas Island is the summit of a submarine mountain, rising steeply to a central plateau dominated by stands of rainforest. This plateau reaches heights of up to 361 metres and consists mainly of limestone and layers of volcanic rock.
Geologists believe that about 60 million years ago the cone of an undersea volcano surfaced, forming a basin on which a coral atoll then began to form. More then 20 million years ago, the atoll appears to have sunk slowly and limestone was deposited as the coral began to build up. Ten million years later, this process stopped and an island began to emerge from the sea in a series of uplifts. Each of the island terraces was formed by the development of the fringing reef and sea cliff erosion before being uplifted. The lagoon drained and the central plateau was formed. Evidence of these volcanic origins can be seen at The Dales, and Dolly Beach where the basalt rock is exposed, forming the bed of freshwater streams.
The island's 80 kilometre coastline is an almost continuous sea cliff, of up to 20 metres in height. In a few places, the cliff gives way to shallow bays with small sand and coral shingle beaches. The largest of these bays forms the island's only port; Flying Fish Cove.
The island is surrounded by a narrow encircling coral reef. There is virtually no coastal shelf, and the sea plummets to a depth of about 500 metres within 200 metres of the shore.
Christmas Island experiences a tropical equatorial climate with wet and dry seasons. The wet season is from December to April when the island comes under the influence of the north-west monsoons. During the rest of the year, the south-east trade winds bring slightly lower temperatures and humidity with much less rain.
Tropical cyclones occasionally pass close to the island during the monsoon season, bringing strong winds, rain and rough seas. Since settlement, no cyclone has been recorded passing directly over the island.
The mean annual rainfall is 1,930 millimetres. Most of this rain falls between November and May. February and March are usually the wettest months.
Because of the oceanic influence, the relative humidity does not vary seasonally as much as rainfall. Humidity usually ranges between 80 - 90%. Temperatures on the island vary little from month to month. The average daily maximum temperature reaches a high of 28° Celsius in April and the average daily minimum temperature falls to 22° Celsius in August.
The Christmas Island red crab is by far the most obvious of the 14 species of land crabs found on Christmas Island. It is estimated that 120 million of these bright red land crabs live in their preferred shady sites all over the island.
Bright red is the common colour but there are the occasional orange specimens and more rarely some purple animals. They are a big crab. An adult body shell (or carapace) may measure up to 116mm across. The Christmas Island red crabs' carapace is round shouldered and encloses their lungs and gills. Their claws are usually of equal size unless one is a regrowing claw. Males grow larger overall than females, while females have a much broader abdomen and usually have smaller claws than males. However young Christmas Island red crabs all have the characteristic narrow abdomen of the male. The broader abdomen on the female Christmas Island red crab only becomes apparent in the third year of growth.
Christmas Island red crabs grow slowly, reaching about 40mm in carapace width after 4-5 years. They are sexually mature at this age and begin to participate in the breeding migrations.
The Christmas Island red crabs moult their shells regularly during their early growth phases to match their increasing body size. Moulting usually takes place in the protected moist environment of their burrows. Mature Christmas Island red crabs probably moult only once a year, as their growth rate slows.
Red Crabs diet consists mainly of fallen leaves, fruits, flowers and seedlings. They prefer fresh green leaves but will eat any fallen leaves. They are not solely vegetarian however. They will eat other dead crabs and birds, the introduced Giant African snail and palatable human rubbish if the opportunity presents itself.
They have virtually no competition for their food resource due to their high numbers and dominance of the forest floor.
Although most common in the moist environment of the rainforest, Red Crabs live in a variety of habitats including coastal shore terraces, and even domestic gardens. Tall rainforest on deeper soils has the highest crab density. They dig burrows in almost every square metre of available soil or live in deep crevices in rock outcrops. For most of the year, a crab will settle in one place, living in their burrow. The crabs' burrows have a single entrance tunnel which leads to a single chamber. Only one crab lives in a burrow and outside of the breeding season Red Crabs are solitary, and do not tolerate intruders into their burrows.
Red Crabs are diurnal (active during the day) and almost inactive at night despite lower temperatures and higher humidity. They take great care to conserve body moisture and this seems to be the single most important factor influencing the crab activity. Sensitivity of crabs to moisture, combined with the seasonal climate on Christmas Island, create a distinct seasonal pattern of activity. Crabs retreat into the humid interior of their burrows during the dry season. They plug the burrow entrance with a loose wad of leaves to maintain a high humidity level, and effectively disappear from view for up to two to three months of the year.
Males lead the first wave of the downward migration and are joined by females as they progress. Larger males arrive at the sea first (after about 5-7 days) but are soon outnumbered by females. The crabs replenish moisture by dipping in the sea, then the males retreat to the lower terraces to dig burrows. The density of burrows is high (1-2 per square metre and fighting occurs between males for burrow possession. The females move to the terraces and mating occurs, usually in the privacy of the burrows that males have dug and fought for. As mating, and fighting, abates, males dip again and begin returning inland. They move quickly, reaching the plateau in only 1-2 days.
The females produce eggs within 3 days of mating and remain in the moist burrows on the terraces for 12-13 days while they develop. The eggs are held in a brood pouch between their extended abdomen and thorax. A single female can brood up to 100,000 eggs.
In the morning and late afternoon around the last quarter of the moon, the egg-laden females descend from the terraces to the shoreline. They pack into shaded areas above the waterline at densities of up to 100 per square metre in places. The females usually release their eggs into the sea toward dawn, around the turn of the high tide. Release of eggs may occur on 5-6 consecutive nights during the main breeding migration. After the first two days, eggless females may be seen crossing plateau roads, kilometres from the shore.
If the spawning migration is delayed or disrupted, usually because of unfavorable weather conditions, both male and female crabs will remain on the terraces for the next month and complete the spawning one lunar month later.
The eggs released by the females hatch immediately on contact with the sea water and clouds of young larvae swirl near the shore before being washed out to sea by waves and tides. Millions of the larvae are eaten by fish and plankton feeders such as Manta Rays and the enormous Whale Sharks which visit Christmas Island waters during the crab spawning season.
After about a month in the ocean, and after growing through several larval stages, the surviving larvae have developed into prawn-like animals called megalopae. The megalopae gather in pools close to the shore for 1-2 days before changing into young crabs and leaving the water.
Although only 5mm across, the baby crabs begin their march inland, taking about 9 days to reach the plateau. Here they seem to disappear and are rarely seen, living in rocky outcrops and under fallen tree branches and debris on the forest floor for the first three years of their life.
In many years, very few or no baby crabs emerge from the sea, but the occasional very successful year (perhaps only one or two every ten years) is enough to maintain the Red Crab population to a high level.
Certain human activities have led to increased numbers of Red Crabs dying during their annual migration to the sea. As well as there being a greater risk of crabs dehydrating when forced to cross areas cleared of forest cover, thousands of adults and young are crushed by vehicles while crossing roads. Red Crab Migration, Indian Ocean, Galapagos. Some have to negotiate up to three or four such hazards on their descent and ascent each year. Conservation measures have been implemented to help reduce this high death toll.
To reduce the number of crabs killed by vehicles during the migration, 'crab crossings' are being constructed in roads which cross main crab migration paths. Points where high numbers of Red Crabs cross roads have been identified, and tunnels are built under the road for crabs to pass through. Walls that the crabs can not climb over are built alongside the road to 'funnel' the migrating crabs through the tunnels. These crab crossings may be seen on the Lily Beach road. Other conservation measures used by the community are road closures and traffic detours around the major migration paths during peak periods of the migration.
With 63% of Christmas Island being National Park, a walk through the rainforest can be both enjoyable and can range from easy to difficult walks. Nature walks will help you discover first hand the Christmas Island endemic flora and fauna. For further information on Nature Walks, contact the Christmas Island Visitor Information Centre or Parks Australia North.
If you are looking for an unforgettable birdwatching holiday, you will love Christmas Island. 63% of the island's 135 square kilometres is national park and the island's close proximity to South East Asia and the equator has resulted in a diverse range of bird species.
The island is large enough to have developed its own unique rainforest ecology. There are hundreds of species of birds with seven of the 13 land birds being endemic to the island, including the inquisitive Christmas Island Thrush, whose melodious evening song lends a wonderful musical quality to the tropical, palm-fringed sunsets.
Many species are quite inquisitive and those on a birdwatching holiday can be rewarded with some truly special sightings. Highlights include the rarest bobby and frigate birds in the world, the Abbotts Booby and the Christmas Island Frigatebird. With little effort is it quite easy to tick off a full list of residents in a busy week or more relaxed fortnight, though the elusive Christmas Island Hawk Owl keeps many coming back for more!
With the coral reefs surrounding the Island, snorkelling is a must on every visit to Christmas Island as the abundance of fish and coral to see is breathtaking, just a few metres from the shore. Popular and accessible Flying Fish Cove is great for snorkelling and swimming.
Christmas Island boasts some of the best scuba diving trips in Australia and has some of the longest drop-offs in the world. The island rises dramatically from the edge of the Java Trench, Indian Ocean’s deepest point. This contributes to the endless kilometres of spectacular drop-off diving with most walls being only 20 metres from the shoreline.
Christmas Island is surrounded by a narrow tropical reef which plunges into a bottomless abyss. This makes it the perfect destination for scuba diving trips! This reef is laced with many unspoiled corals and abundant species of marine life. The northern coast in particular boasts some of the most unspoiled corals in the world such as Acropora and plate corals which play host to a wide variety of small tropical species such as surgeon fish, wrasse, butterfly fish, gobies, anemones, eels and many others which are a photographers delight.
You may also be paid a visit by one of the larger locals on your scuba diving trip. Pelagics like rainbow runner, trevally and tuna cruise along the walls and the occasional shark comes up for a curious look.
You could be graced with the presence of the majestic whaleshark. An encounter with one of these gentle giants who often visit any time between November and April is an experience on your scuba diving trip that you don't want to miss!!
On the world map of fishing locations, Christmas Island may only rate a small dot, however fish being caught here are making a big mark amongst the international fishing fraternity. The secret is out... anglers around the world are starting to find out that Christmas Island is the hottest new spot for big fish in South East Asia.
Within a few hundred metres of the boat launching facilities, it is possible to fish in 500 metres of water for Sailfish, Tuna, Wahoo and all the other exciting species that you usually find in tropical locations. The difference is that on Christmas Island the fish are BIG, very BIG!
When the ocean currents bring the the tuna in, it is possible to see fish in excess of 100kg feeding on the surface. While the Yellowfin Tuna roam and pass the island quite regularly, Dogtooth Tuna live permanently on the steep drop-offs that surround Christmas Island and we’ve seen them up to 80kg landed. Or if you prefer the high flying aerial displays of a sailfish, during the pre-monsoon months some of the biggest Sailfish in the world are to be found at Christmas Island. Even trolling within a few hundred metres of the shoreline you will find the razor gang. Wahoo are the fastest fish in the world and Christmas Island is their favorite race track!
Golf is one of the favourite pastimes of Islanders and the Golf Course is well worth a try for professional golfers or first timers. The 9-hole golf course is situated amongst palm trees and tropical rainforest with a magnificent view of the Indian Ocean. Green Fees of $10 per round are payable for non-members. Clubs are available for hire from the Christmas Island Visitor's Centre and visitors are most welcome. Christmas Island Frigates nest inland from the course and land crabs can be a local hazard.
Western and Asian Food - Coffee, milkshakes and cool drinks. Located at the Christmas Island Recreation Centre. Open :Everyday Phone :+61 8 9164 8106
Golden Bosun Tavern
Rocky Point Complex, Gaze Road Settlement. Modern International fare, with a dessert selection and coffee. Uninterrupted views of the Indian Ocean from the restaurant verandah Dinner served 6 nights per week, closed Monday. Restaurant : 5.30pm - 8.30pm Bar : 4pm till late Phone :+61 9164 7967
Mon - Fri :Fresh bread daily including white, wholemeal, wholegrain and 6 cut rolls Red bean paste; Kaya paste; Coconut and Sambal Prawn buns Chicken and Beef Sausage Rolls Sat :Closed Sun :Fresh bread and french sticks Available from Boong Trading, Meng Chong Trading, and Metro Enterprises.
Huge range of burgers, rolls, sandwiches, delicious meals and fresh salads, Fresh coffee and cakes BYO - Eat in or Take away Open :6 days 7:30am - 1:30pm (closed Sunday) Phone :+ 61 8 9164 7688
Rumah Tinggi Tavern and Restaurant
Gaze Road Settlement. The Rumah Tinggi offers modern Australian fare, fine wine and cocktails. With uninterrupted views of the Indian Ocean and a spacious open air verandah - the perfect location to watch the sunset or the moon rise over the Indian Ocean. Bar open 5pm till late - Dinner - 9 pm. Closed Tuesday and Wednesday. Contact :Mark or Kaz on + 61 8 9164 7667
Poon Saan area - upstairs from the Poon Saan Shops. Offers authentic chinese dishes in air conditioned comfort. Phone :+ 61 8 9164 7688
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