Monday, January 31, 2011

Are Freshwater Crocodiles Going Extinct?

Barely a week into 2010 and already the crazy crocodile stories are starting to appear. This one concerns the possible decline of freshwater crocodiles at the hands of expanding saltwater crocodile populations. The story itself is clearly prompted by the release of the revised management plan which contains a graph showing the apparent decline in freshwater crocodiles detected during surveys of the Daly River.

I'm not sure that I'd be leaping to such conclusions based on the findings of one river system's survey results just yet, especially considering the variability inherent in survey results. There's no information in the report, for example, to assess the impact that changing the survey methodology in 1998 (the first year of the apparent decline) had on the results. It's a good point to bear in mind when assessing croc survey data.

But I digress. Let's say that the decline is real (and I suspect it probably is). The news article implies that this is a real problem for freshwater crocodiles, with one noted expert even suggesting that freshwater crocodiles might be "on the way out". That sounds pretty dramatic! However, I think the point is being missed because there's a very reasonable explanation behind it. When saltwater crocodile populations were protected in 1971 (in the Northern Territory) there were only a few thousand left hiding in backwater swamps and creeks. Early crocodile surveys conducted by Harry Messel from the University of Sydney found that freshwater crocodiles had moved a long way downstream. There were even some freshwater crocs found in estuarine areas. This told us two things: first, that "freshwater" crocodiles are much more tolerant of saline water than their name implies, and secondly that freshwater crocodile populations are largely restricted to upstream areas by saltwater crocodiles. Take those saltwater crocodiles away, and freshies are free to move a lot further downstream.

You can probably see where this is going. Since saltwater crocodiles have recovered in the last few decades, they have progressively reclaimed territory that was formerly "theirs". Freshwater crocodiles have been pushed back into their more usual haunts: upstream freshwater and low escarpment habitat. So it's really not surprising to find that in the last decade, this trend has continued with densities declining in more downstream areas as saltwater crocodile populations mature and their size demographic becomes increasingly biased towards larger adults. Suddenly those Daly River results don't seem so surprising.

In straightforward terms, freshies have had it too good for too long! If there's one thing we know about crocodiles, it's that they are opportunists. We know they're happy to disregard notions of territory if there's plenty of food around, and we know that most species will range into less suitable habitat even if it means not growing so quickly or being able to breed. Being long-lived gives you a bit of flexibility with such things. Species are also frequently sympatric (sharing the same habitat) in areas where there's plenty of food and space. The Daly River is one example, but there are plenty of others where it would be very informative to see if similar trends exist. Unfortunately freshwater crocodiles haven't really been a management priority in the last decade and a lot of these trends have been lost. Perhaps the decline in the Daly River reflects a reduction in available food for both species? It certainly warrants further investigation.

These dynamic interactions between saltwater and freshwater crocodiles make even more sense when you consider recent fossil evidence showing that freshies very likely evolved from salties. Resources and habitat partitioning led to speciation in the ancestors of saltwater crocodiles, and freshwater crocodiles became perhaps better suited to the more extreme habitat conditions where food and nesting resources are less readily available. Populations are very dynamic concepts, and that includes their genetics.

So are freshies really on the way out? They're reverting to a familiar relationship that they've shared with saltwater crocodiles for thousands of years, where healthy saltie populations deny access to most downstream areas. That in itself wouldn't be a worry if other conditions remained as they were. However, since then cane toads have devastated freshwater crocodile populations in many areas. Could the combined onslaught of saltwater crocodiles and cane toads lead to the disappearance of freshwater crocodiles? Some people might think so, but I have more faith in this species' tenacity. They've already proven capable of thriving in some pretty unlikely habitats (dry, seasonally flooded, upstream escarpment) and they've largely survived the cane toad onslaught albeit in reduced numbers. Even now, they are adapting to new circumstances as they have done for millions of years. The question is, can they adapt quickly enough if anything else is thrown at them. What about climate change? What about the most vulnerable and possibly unique "pygmy" populations? Although I doubt we'll be seeing the last of freshwater crocodiles anytime soon, we're not making life easy for them.

Psychic crocodile

Well, if I'm going to get this blog rolling again, why not start with a crazy, cash-in story?! I'm sure most people are aware by now of Paul the "psychic" octopus who has an unbroken record of accurately predicting the matches that Germany won and lost during the 2010 World Cup in South Africa. Well, Crocosaurus Cove in Darwin has clearly decided to ride the wave of anticipation over Paul's latest prediction that Spain will win the World Cup final by doing their own prediction... with a large saltwater crocodile.

And who did "Harry" the crocodile pick? Well you should click the link and watch the video to see the action as it happened, but let's just say that the animal kingdom's reputation is at stake here!

I'm sure normal programming will be resumed shortly.

Australia's "monster" crocodile

This photograph has been doing the rounds lately. It purportedly shows a giant 6.5 metre (22 foot) saltwater crocodile that was shot in... well, there's the rub. There seems to be some disagreement about whether it was shot in Queensland, or the Northern Territory, and therefore who owns Australia's largest (dead) crocodile. This disagreement has spilled over into the international media, all of whom love a good story about giant crocodiles.

There's only one problem with all this. That crocodile is certainly not 6.5 metres long. Not even close. If you ask me, it's probably a little over 5 metres long. How do I know this? Well, all the clues are in the photo. First of all, that truck (a Toyota Landcruiser FJ40 series station wagon) is roughly the same length as the crocodile, give or take. It's hard to tell because the back of the crocodile's tail isn't in the shot. So how long is that truck? It's around 4.7 metres. Secondly, the photograph uses all the classic perspective tricks to fool the eye into emphasising the size of the crocodile - low to the ground, wide-angle lens, small child in the foreground, truck in the background (the distance could be several metres, further exaggerating the size of the crocodile). And if that wasn't enough, the crocodile is clearly starting to bloat from decomposition, making it look even larger. So if you add all this up, look at the size of the truck and where the crocodile is positioned in relation to it, considering how much of its tail is missing, it can't be much more than 5 metres long. That's around 17 feet at best. That's certainly a very impressive, very large crocodile, but it's nowhere near the size they're claiming, and it's certainly not the largest croc ever found in Australia.

Whoever wants this crocodile can have it. Not only is it not particularly noteworthy, it's probably a bit on the nose by now judging from the age of the photograph.

Thursday, January 27, 2011

Crocodile: "Is it time for my dental check-up?"

This crocodile was lurking in the underbrush on the banks of the Tempisque River in Palo Verde National Park. His color matches the mud bank quite well, although he is certainly not as camoflauged on the river bank as he is when he is floating just under the surface of the water.

This close-up of the crocodile's head demonstrates how tour operators can take tourists in boats on river cruises to view the wildlife up close in their natural habitat. It is similar to the Jungle Cruise ride at Disney World or Disneyland, except the animals are real, of course, and the tour guides do not have a microphone and do not give a narrative of corny jokes and puns.

Four of the 23 species of crocodiles are found in the Americas, and two of those four are native to Costa Rica -- the American crocodile and the caiman. This is an American crocodile, which can reach 7 meters (21.5 feet) in length. Some crocodiles can live more than 60 years in the wild. (I will post more crocodile and caiman photos in the future.)

This crocodile allowed us to get so close I could zoom in on his head. You can enlarge the photo to check his teeth. Is it time for his dental check up? Costa Rica has very good medical and dental care, and there is a growing trend of people from the USA coming to Costa Rica for medical or dental procedures that are not covered by insurance at home. The savings can more than pay for a vacation while recuperating.

Crocodiles don't go the dentist of course. They can get their teeth cleaned by one species of bird that picks insects off them and can even clean their teeth without being eaten like all the other types of birds that the crocodiles encounter. This remarkable cooperation between species is something biologists would call "mutualism."

Crocodile, Up Close and Personal

This is my favorite crocodile photo. This was a rare chance to look upwards at a crocodile in the wild from an angle to photograph the underside of his chin.

I was so close to this crocodile that an instant after I took this photo the crocodile rushed into the river and I got splattered with mud as he dove into the water. (Yes, I did use a telephoto zoom, so I was not as close as this photo appears.)

I took this photo from a wildlife boat excursion on the Tempisque River in Palo Verde National Park. Usually the crocodiles visible on such trips are in the mud along the river banks. This crocodile was up on the river bank, and the boat operator glided the bow of the boat into the river bank so that we could watch the crocodile up close. The boat is a good size, holding 20 or so people, so there is no danger from the crocodile on the boat.

As you can see from this photo angle, the crocodile was higher in elevation than the boat. Instead of the usual crocodile photo looking down on the top of his head and back, I was able to get a shot looking up to the underside of his chin. To get the best angle, I went to the side of the boat, leaned over with my camera hanging from my neck, and held the camera as low as I could, just above the water, to get a better angle to shoot up at the crocodile.
This crocodile was in the wild. He was not in a fenced in enclosure in a wildlife park or zoo. To get a photo this close and at this angle, the driver of a wildlife viewing boat excursion on the Tempisque River at Palo Verde National Park beached the boat for a few minutes so we could watch the crocodile. After a few minutes, he scampered down to the river to swim off, and I got this photo looking down at him from a rather close up perspective. Another photo I will post in the future will be a picture of crocodile who was so cloe that he splatttered mud on my shirt as he scampered into the water.


This is a close up of a caiman. Caiman are similar to crocodiles, only smaller. They are only about 2.5 meters (8 ft.) in length. They are not as aggressive as crocodiles and are generally considered not to be a threat to people. You will also notice that they do not have as large a set of teeth as crocodiles, and they do not have the the large tooth that protrudes upward from the lower jaw about 4 teeth back from the tip of its mouth.

Caiman are common in Tortuguero. On our boat ride meandering through the backwaters of Tortuguero, we saw more than 10 caiman in three different locations within the span of about an hour.

Caiman head

We will transition from the photos of a poison reptile during the last two days to another reptile. This is a close up of the head of a caiman. I apologize that the photo is not sharper, but he was lurking in a shadowy area of a river in a dark area of the jungle. You can see the vertical slit of his eyes.

He was very still, lurking below the water's surface, waiting for a bird or other prey to come near.

Is the crocodile moving in for the kill?

As we watched the crocodile lurking in the underbrush along the muddy river bank, the crocodile slowly slithered through the mud towards the heron.

I felt like I was watching one of the episodes of the old television program Mutual of Omaha's Wild Kingdom. Where was the voice of Marlin Perkins calling to Jim Fowler, 'The heron could make a tasty lunch for the ravenous appetite of the relentless predator crocodile, whose sharp teeth and gaping mouth would devour the bird in one lightening quick strike."

Safety for the heron

Fortunately, the crocodile was more interested in going into the water than attacking the heron. Maybe the bird consists of too much feathers and bones and not enough meat to interest the crocodile.

I suspect that the bird knew that the crocodile would not attack it, as it did not fly away, or even walk down the river bank, as the crocodile moved along side the bird and then went into the water.

Tomorrow I will show you 32 of the 64 reasons that this bird should be pleased that the crocodile went right past the bird and into the water.

Crocodile and his teeth

I count 32 teeth in this photo. Assuming that the crocodile has the same number of teeth on the other side, that would make 64 teeth to grab, slice into and chew its prey. The extra large fourth upward tooth is distinctive of a crocodile and is a way to distinguish between crocodiles and alligators.

I am relieved that the crocodile did not attack the heron that I showed during the past few days. Fortunately, the crocodiles in the western hemisphere are not as aggressive as the Nile crocodile, but people should keep their distance nevertheless.

When people who rent our condos in Tamarindo ask about activities for their children, I always recommend the nature tours on boats in Palo Verde National Park. I describe it as being similar to the Jungle Cruise at Disney World or Disneyland, except that the animals are real, and the tour guides do not recite a memorized script of corny jokes and puns.

I think it is an enriching, entertaining and educational experience for young people, and for us adults too, to watch wild animals in their native habitat. The people who stay in our condos often tell me that they have enjoyed the excursions and that their children have returned home with enthusiastic stories to tell their friends of seeing crocodiles, monkeys and other animals in the wild.

Spooky crocodile for Halloween

Lurking in the river.
Blood without heat.
Eyes of a killer.
Trick or treat.

Crocodile thrashing

The crocodiles that I have shown on this website have generally been rather still. I therefore decided today to show a crocodile in motion. I realize that you can't see very much of him, as he has kicked up a splash that has obscured the view of him as he lunged and spun in the water. A portion of his back is visible to the side of the splash. I stayed safely in the boat.

I once leaned over the edge of the boat so I could get an angle shooting up at a crocodile on the river bank and he darted into the water so close that he spattered me with mud. He surprised me with how fast he moved. The splash of the water in this photo gives an indication of the speed and force of crocodiles when the move in the water.

Crocodile coming up out of the water

Here is a different reptile than the calm, harmless iguanas that I have shown several times during the last month. Unlike the iguana who was very close to me in the photo I showed yesterday, or the series of the iguana at the Tamarindo airport that I showed several weeks ago, here is a crocodile that you would not want to encounter in the wild, except from the safety of a boat.

Yes, this crocodile is in the wild. I was in a boat, no more than 4 or 5 feet away (less than 2 meters). He was expecting the wildlife tour boat operator to throw out some food, so he came up out of the water to get a look and to be positioned to chomp on the food.

It is common to see crocodiles on wildlife boat excursions in Palo Verde National Park. Usually, however, they are lurking just below the surface of the water with just their eyes and nose visible or lying in the mud on the river bank. It is very unusual to see the head of a crocodile angling all the way out of the water.

crocodile on the river bank

This is a more traditional view of a crocodile. Compared to this crocodile, yesterday's crocodile looks like a dolphin at Sea World doing tricks.

Crocodiles can move surprisingly fast. Once I was photographing a crocodile on the river bank, from the safety of a boat, of course, and he darted into the water so fast that he splattered me with mud before I could pull back into the boat.

Today is Sunday, so we have new photos posted on our Viva la Voyage travel photo site. Our photos this week show the Dalmatian Coast of Croatia. If you have not been there, please check out the our website this week. You are in for a treat.

hey Nice Crocodile

The crocodile in this photo does not look mean, does he? He looks almost friendly, if you can overlook the many sharp teeth.

Crocodiles look menacing when lurking at the surface of the water. Crocodiles look terrifying when their mouths are open.

Tune in again tomorrow. Today's photo is a tease.

I took this photo while on a wildlife boat trip in Palo Verde National Park. I recommend these trips to the people who rent our condos in Tamarindo.

Photo of a fierce, hungry crocodile

OK. This is not a nice crocodile. This is a photo of a large, hungry crocodile.

Several people yesterday left comments that they hoped my crocodile photos were taken with a telephoto lens. They were not. I took this photo from a distance of about 6 or 7 feet, a little more than 2 meters. I was in the safety of a boat.

You can tell from the angle of the photograph that I was shooting down on the crocodile at close range, as I could not get this angle if I were far away from the crocodile.

Once I was taking a photo of a crocodile on a river bank at such close range that when he scampered into the river he splattered me with mud.

Because of the comments I had yesterday, I will change my post for tomorrow and show the type of boat used for the wildlife trips for photographs such as these.

Blue jeans poison dart frog

This strawberry poison dart frog, also called a blue jeans poison dart frog, is one of 7 species of poison dart frogs in Costa Rica. They are poisonous to touch if you have a cut on your hand, but I do not touch them just in case.
They are tiny. Most are only about 2 cm (1 inch) in length, and large ones get to about twice that size.

Poison dart frogs display remarkable parenting behavior for animals other than mammals and birds. Their courtship ritual includes the male calling a mate, then she follows him to a suitable site for laying eggs, usually a moist leafy area. After some foreplay rubbing and touching, the eggs are laid and fertilized. This rather typical frog behavior is followed by something very unusual.

Either the male or female stays with the eggs to guard them until they hatch into tadpoles. The parent will then pick up the tadpoles and carry them on his or her back up a tree and deposit the tadpoles in the little pools of rain water that gathers in the the central areas of bromeliad plants. Even more amazing, the female frog will return to the tiny puddles of rain water and deposit unfertilized eggs for the tadpoles to eat.

How many amphibians or reptiles care for their young with such devotion? Even the fathers are involved. One difference between the fathers and mothers is that when they carry the baby tadpoles up the trees to the bromeliad sisterns, make frogs will carry up to 6 tadpoles at a time, but mothers will carry only 1 or 2 at a time. I guess the males must have better upper body strength from all those years carrying the trash out of the kitchen on trash collection day.

I previously mentioned how Tortuguero gets so much rainfall each year. The rain and humidity are obviously necessary to maintain the supply of water in the little pools in the plants to nurture the tadpoles.

Please excuse the quality of the photos. The forest canopy is thick, so I took the photos in low light and zoomed in, which narrowed the depth of field. The top photo is cropped to enlarge the frog. The second photo shows the full frame. I did not want to get closer and disturb the frog.

I will show another poison dart frog in a few days.

Poison Dart Frogs and him

La Fortuna Costa Rica has its fair share of Poison Dart Frogs... but luckily, there's only ONE michael alan.

love, Love, LOVE the Strawberry poison dart frog. Well, around La Fortuna Costa Rica, we call it the 'Blue Jean Frog' for obvious reasons. Yup, it's poisonous, how poisonous depends on who you ask. And in this picture I'm eyeballing it just make sure it doesn't decide to jump in my mouth.

If you're ever in the La Fortuna/Arenal area, you can find the 'Blue Jean Frog' without a Guide if you just follow one of our travel tip videos, this one to be exact: La Fortuna Costa Rica- the Secret REVEALED. I highly recommend visiting 'Salto' regardless if you're interested in frogs or NOT.

Here's some pics and INFO on the Strawberry Poison Dart Frog aka Blue Jean Frog:

This lil' Blue Jean Frog doesn't look to happy that we're taking its picture.

A Few Facts about the Dendrobates Pumilio aka, The Strawberry Poison Dart Frog or Blue Jean Frog:

* Found mostly in the tropical forests of Central America.

* Strawberry poison dart frogs are fairly little and only grow to be about 1/2 to 2 inches long. They are bright red with blue legs and are often called the "blue jean frog" because of the brightly colored top and blue legs. The beautiful, bright colors are warnings to potential predators that the frogs are poisonous.

*Poison dart frogs fertilize their eggs externally, that is to say, the female lays a clutch of eggs and a male fertilizes them afterward, in the same manner as most fish.

* Strawberry poison dart frogs take their parenting seriously (taken from the folks at WIKI):

The red-and-blue poison-arrow frog (Dendrobates pumilio) carry their newly hatched tadpoles into the canopy. The tadpoles stick to the mucus on the back of their parents. Once in the upper reaches of the rainforest trees the parents deposit their young in the pools of water that accumulate in epiphytic plants such as bromeliads. The tadpoles feed on invertebrates in their arboreal nursery and their mother will even supplement their diet by depositing eggs into the water.

* Strawberry poison dart frogs are diurnal which means they're active during the day, unlike most frogs that are nocturnal (active during the night).

* They use their long sticky tongues to capture preys like spiders, small insects, ants, termites and small crickets. According to scientists, these insects acquire the poison from their plant diet, which can be the source of toxicity in poison dart frog.

* Male Strawberry poison dart frogs are extremely territorial and will wrestle other males for territorial rights.

* The lifespan of the Strawberry poison dart frog seems to be speculative at best, I've read anywhere from 3-16 years in the wild and up to 35 years in captivity. In captivity they tend to lose their poisonous toxins due to diet.

HIS and HERS Strawberry Pois

Coolest Colored but Most Poisonous Frog

Coolest Colored but Most Poisonous Frogs 1
Coolest Colored but Most Poisonous Frogs 2
Coolest Colored but Most Poisonous Frogs 3
Coolest Colored but Most Poisonous Frogs 4
Coolest Colored but Most Poisonous Frogs 5
Coolest Colored but Most Poisonous Frogs 6
Coolest Colored but Most Poisonous Frogs 7
Coolest Colored but Most Poisonous Frogs 8

World's Smallest Frog Packs Poison Punch

The record-holder for the smallest frog in the world apparently makes up for its miniature size by packing a wallop of poison, research reveals.

With a body that's only 10 millimeters long, the Mount Iberia frog (Eleutherodactylus iberia) from Cuba currently holds the Guinness World Record for smallest frog.
The smallest frog in the world would fit (with room for a buddy) on your fingertip. Credit: A. Rodriguez and M. Vences.

Investigating these dwarf frogs is painstaking work, said researcher Miguel Vences, an evolutionary biologist at the Technical University of Braunschweig in Germany.

"You have to crawl on your knees and move leaf by leaf," Vences told LiveScience. "And when you discover one of these frogs, they usually jump away immediately so that you have to start all over again."

When Vences found his first specimen, he smelled a bitter odor and suspected it might be coated in toxic alkaloids. (Morphine and caffeine are alkaloids.)

"At the time I just mentioned this as a crazy and rampant speculation - I was sure it would prove to be wrong, and was even more surprised when my chemistry colleagues sent me the first results, stating they indeed had found alkaloids in the skins," Vences said.

Only four other groups of frogs in the world secrete defensive toxins onto their skin, including the infamous poison-dart frogs of Latin America. It remains uncertain precisely how deadly this new poison dwarf might be.

The researchers suspect these dwarfs evolved their tiny size to better prey on mites overlooked as meals by larger frogs. These arachnids possess alkaloids the dwarfs secrete on their skins. And so by consuming the poison, the frogs somehow reallocated the goods for their own use. It was only later the frogs might have evolved their brown, yellow-striped appearance - "such a contrasting coloration usually is found in poisonous animals, which use it to deter potential predators," explained researcher Ariel Rodriguez of the Institute of Systematic Ecology at Havana.

A variety of tiny frogs roughly 10 millimeters long can be found around the world. These poisonous new findings could shed light on why this dwarf became so tiny.

"A more important question is probably why did the frogs not get even smaller?" Vences said. "In birds and mammals, who have to maintain a stable body temperature, you can understand why they cannot get smaller than a dwarf shrew or a tiny hummingbird - as the body surface relative to body volume increases as you get smaller, you are cooling more easily, so you need more energy to maintain your temperature. This only works to a certain size well above the 10 millimeters found in frogs."

However, frogs, being cold-blooded, do not need to maintain a stable body temperature.

"So what is the limiting factor? Is it ecological, that there is not enough prey available for frogs under 8 to 10 millimeters?" Vences speculated. "Is it developmental, some fundamental processes in the body, like producing eggs, not being possible in smaller frogs? Physiological, related to water loss? In these questions, I see the greatest challenge, and this is where studies of miniaturization of vertebrates will be able to provide data of more fundamental importance, far beyond the pure curiosity of just their dwarf size."

The scientists detailed their findings online Nov. 3 in the journal Biology Letters.

Green Vine Snake eating bird

This beautiful snake is a Green Vine Snake (Oxybelis fulgidus), and is common in Tortuguero, Costa Rica.

I found it today in one of the nets as it was trying to eat a hummingbird!

When I found it, the hummingbird was already dead. I do net runs every half hour, but I was too late for the juvenile Rufous-tailed Hummingbird that the snake is trying to eat here.

Hummingbirds are often less entangled in the nets than other birds, and the snake certainly had a chance of picking it out of the net, just as the hummingbird had a chance of flying out.

But the poor little hummingbird was stuck in the net and couldn't get out; for the same reason, the snake couldn't eat it.

These snakes can get over 2 m long. This individual was about a meter and a half.

Man of the hour Walt Sakai got the snake out of the net. I had no idea if this thing was going to be poisonous, so I exercised the necessary caution. Next time I find one in the nets, I'll remove it myself.

I do net runs every half hour here, which is more frequent than at many other banding stations, mainly to prevent birds from overheating should they get caught in a sunny spot. Apparently, other dangers are lurking too. This is the first bird that died during my time here. I hope it will be the last also.

14+ Most Beautiful and Amazing Captured Snake Photos to Praise Nature

Here are some beautiful and amazing Snake Photos captured by camera with different styles like Heros, hope they will make you to Praise Nature created by God. Although Snakes are very dangerous animals(Reptiles) but they are beautiful also by some another eye.

I have gone through browsing and found some of such photos that make me Praise Nature.
Take a Look :)