The Cave of Death is not much of a cave, so to speak, but it is a really fascinating hole in the ground nonetheless.  Extending only about 10 feet into the hillside, it ends at a crack too small to continue.  That is, if it were reasonable to continue for other reasons.

Located on the flank of the Poas Volcano in Costa Rica, the Cave of Death just happens to be near some very nice hot springs which have been developed into Recreo Verde.  This fine place was our base camp, actually a fabulous cabin, for our work in this area.

And as for the cave, it is a bit of a tourist attraction, and probably one of the few commercial caves where one does not in fact go in the cave.  Why?  Good question and glad you asked.  The reason for the name is fairly simple, as the cave itself is a huge emitter of nearly pure carbon dioxide.  This, as one might suspect, is what could mildly be called, "bad air" and it is quite dangerous and often fatal to animals that enter the cave.

But, since carbon dioxide is heavier than air, the "bad air" is mostly along the floor, and in fact pools up at the entrance with the spillover rolling out of the cave and along the ground.  How do we know this?  Another good question!  Guy van Rentergem invented a clever little smoker device out of an e-cigarette machine, which could be placed in specific spots to see exactly where the gases were going.  As well, we used a carbon dioxide meter to determine where the gas was and in what concentrations.

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Note that the signs in the photo helpfully say "toxic gas", "entry prohibited" and "don't throw trash".  The last one is kinda funny, compared to the others, until you realize that any trash thrown in the cave is rather hard to retrieve since you can't just go in there and pull it out.

And just to be thorough, we tracked the gas with smoke all the way out of the protective barrier at the cave's entrance where it eventually drifts off in the breeze, while staying right along the ground.
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And while Don McFarlane was taking a number of scientific measurements and recording data and just being an all around science guy...
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It still baffles me as to exactly what he was doing here...

Anyway, one of the more notable features of the cave is the pool of carbon dioxide on the floor, which is remarkably stable, and nearly 100% CO2.  It is just deep enough that any small animals that go in there, end up in that oxygen-free zone and quickly pass out and die.  The Recreo Verde folks told us that the most common animals that die in the cave are rats, snakes and small birds.  And, just looking in we could see at least one fairly recent fatality (sorry, I can't get a species from this photo).
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The smoke was really useful at showing the gas movement out of the cave, but what would it do when placed under the level of the carbon dioxide pool?  Man, you have all the great questions today!  Turns out that the gas has a very slow-moving eddy effect going on, and after a minute or two of watching the smoke it looked like a galaxy was forming.

And just for an added attraction here at Tropicalbats.com, a video about the cave from none other than Guy van Rentergem!  

So that is the Cave of Death, a carbon dioxide-emitting hole that has a penchant for killing small animals.  And now I know you have one more question:  Did any of us actually go in there?  I end with this photo...

***Huge thanks to Recreo Verde for allowing us to study their most interesting little cave.  Awesome place to stay on all accounts and really enjoyed it there.

Every time I post an image of a great blue heron, I say it will be my last.  And then I post another one.  In order to fix this I shall hereby state that this will not be my last great blue heron image, as for some reason I just keep coming up with reasons to post pictures of them.

This most patient bird was on the beach right in front of the Campanario Biological Station.  And it would stand there for long periods of time, while only once catching a fish.  It ate a couple little things it found near the rocks at one point, but it's fish to time ratio was pretty relaxed.

Now what does a person do when they are at the ocean and a larger than average wave comes in?  Toss up their hands and let it go by, right?  Now what does a great blue heron do when they are at the ocean and a larger than average wave comes in?  Here is the answer...

Also on the beach was a spotted sandpiper.  Not sure if it is resident or heading north.

And finally, to end on a colorful note, I ran into this shining honeycreeper down the shore a ways.  Quite stunning birds and must say I didn't do a great job capturing the colors, but what a striking bird to see.

The common pauraque, a bird in the nightjar family related to the whip-poor-will, likes open spaces and nests on the ground.  During the day they don't much fly and are pretty much invisible due to their coloration, but since they are night fliers they do have special eyes.  Which glow bright orange at night when hit with a headlamp, and I easily spotted this female on a nest beside the access road at the Firestone Center.  
Normally they will let you get within 2 to 3 meters before flying off, but when on the nest they just stay put and I was able to get right up next to this one for the photo.  Very attractive birds and not sure I really captured how pretty they are in the pic.

Alright, this has been a real struggle to get anything up given the conditions here in Costa Rica, but finally got all the pieces together and can put up a couple posts tonight.

And, without further ado, finally, another photo on the blog which has been very quiet during the winter break.

These toucans can usually be found on the property, and are heard calling most days.  But getting a real nice look at one can be tricky.  I was just starting a hike of the property at the Firestone Center for Restoration Ecology (FCRE or Firestone Center for short) when I saw this beautiful bird.  it was, surprisingly, alone as I generally see two or more of them together.

I usually wait until Spring to end my blog's winter hibernation, but this Coopers hawk was hanging around for a few days and didn't seem to mind people very much.  So it got its picture taken and here it is!

Don't know if I've posted a close-up of one of these before, so here is one.  This is a dark-eyed junco, which in West Virginia is typically the slate-colored variety.  Nice little birds that tend to fly near roadsides in the evening so I catch them in the bat nets fairly often.

I often am asked about getting bitten by wildlife.  Generally the answer is the same, that other than mosquitoes and the like, I don't get bitten by stuff unless I have to handle it.  And then, well, things bite, so just don't handle wildlife, okay?

But it's my job to grab things and do stuff, like measure ear length or weigh them.  Lots of things depending on the project I am on.  So yes, I get bitten.  And this has become a point of question again since I posted in a side note that scarlet tanagers bite, but that it doesn't hurt much.  

Different species tend to either bite a lot, or not.  Some birds never seem to realize that might even be a thing, while others, most notably the chickadee, do nothing but try and bite.  Some can give a pretty good pinch, especially the ones with a strong bill like a grosbeak, but mostly it really isn't hard enough to do much.

And, one of the times I am most likely to get bitten is when taking the photos to document the species capture.  See, when taking animal measurements I can control the whole animal including the mouth, but for the photos the head needs to be fully in the clear.  Which of course allows it more freedom to take a nip.  So while I normally just ignore the photos that don't well-document the species for our records, I do have other ones that show what the animal was doing while I was trying to get a good pic. 

And to satisfy curiosity, here is what a bite from a scarlet tanager looks like.  See, not much, but if it gets you in the soft spot between your fingers you'll know about it.

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We saw a lot of scarlet tanagers flying around during the day, but one evening just after opening the bat nets at dark I caught a female in the net.  They tend to bite, but it doesn't much hurt.  And obviously the female is not exactly scarlet, but a fine shade of greenish yellow.  This bird was quickly photographed and released so it could get to its night roost without much delay.

Took a walk and had a picnic lunch at Kenilworth Park and Aquatic Gardens today.  This site is run by the National Park Service and is located in the top corner of Washington, DC pretty much right on the Maryland line (walked into Maryland during the hike).

It's a darn nifty green space right by the Anacostia River and has about 1 billion small ponds full of lilies and lotus and similar aquatic plants.  Quite pretty place and a bit unique.

Along the trail spur that goes from the Park to the River we saw this yellow-billed cuckoo and got a pretty nice look at it as it was feeding in the trees by the trail.  I like cuckoos, and the fun fact of the day is that they are in the same family as the roadrunner!  Oh yeah, can you guess the name of the family?  How about Cuculidae...a rare case of the Latin being pretty easy to remember.

The slaty-tailed trogon is just one of the most beautiful birds.  We were over at the neighboring Hacienda Baru to get permission to catch some of their mosquitoes (how hard was that!) and I got a chance to take a short walk to the beach.  Along the trail was this trogon just sitting and hunting as they tend to do.

But while taking a couple photos it made a quick attack flight and landed nearby with a large caterpillar in it's mouth.  Even though I wasn't all that far away, there was no way to see what kind of caterpillar it was.  But when I looked at the photos it is clearly one of the snake-headed caterpillars.  I am not really sure of the ID even from the photo, but probably Hemeroplanes ornatus which is one of the sphinx moths.

Very cool, so take a close look at the caterpillar and you will see two "eyes" and a very triangular snake-shaped "head".  So totally cool that the bird wasn't fooled by this obvious defense strategy, probably plucking it off so fast it didn't have time to do the "look like a snake" thing.  These caterpillars are even known to make a striking motion and really have the whole snake thing down.

And as an end note.  Most animals seem to prefer to eat prey head first.  So, the bird gave the caterpillar a quick flip toss spinning it around so the head was at the beak.  And down the hatch it went.