here’s looking at you

A blackish oblong shape moved slowly across the road toward my front lawn the other day.  I had no idea what it was until it got much closer.

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A rather large snapping turtle was moving from the lake across the street from my front yard to the ponds beyond my backyard.

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Large, widely spaced eyes help them see a wide range of view, but not when their head is pulled back into their shell.  

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snapping turtle mimicking a cobra?

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Is this how it sees what’s ahead?

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finally on the move again….

Snapping Turtles are fearsome predators, with powerful jaw muscles that can close the mouth with such force and velocity they can bite a small pineapple in half, or amputate human fingers.  Needless to say, I left this one alone.  They are at or near the top of the aquatic food chain as adults, but take 15-20 years to mature to reproductive age.  Few snapping turtle hatchlings survive to adulthood, but adults are very long-lived.

The Ghost Ranch bone bed

Red rocks at Ghost Ranch, New Mexico

Red rocks at Ghost Ranch, New Mexico.  The oldest exposed rocks (striped gray and red at the cliff base) are the source of the Ghost Ranch fossil beds.

It’s hard to imagine these magnificent mesas as lake or sea bottoms, but the scenery 200 million years ago during the Triassic period at this location looked much different.

coelophysis dinosaurs from the Triassic period

A herd of small carnivorous Coelophysis dinosaurs patrols the shallow lake waters for fish, insects, and other small prey.  Mural at the Oklahoma Museum of Natural History by Karen Carr.

A bonanza of fossilized skeletons of this little dinosaur were discovered on Ghost Ranch property In the 1940s — dozens of immature Coelophysis along with other unique specimens from that period were buried together perhaps as the result of a flash flood.

Coelophysis fossil bone bed

Artist’s rendering of the intact Coelophysis skeletons in the fossil bone bed. From the New Mexico Natural History Museum.

Lake Abiquiu from Ghost Ranch

Rainfall flows quickly down the sides of the mesas, carrying large rocks and debris toward Lake Abiquiu in the distance. The area is prone to such flash floods today, and similar processes may have been responsible for the deposition of Triassic organisms.

Collared lizard

Lizards, like this Collared lizard, and snakes are the primary reptilian predators on the mesas today.

Red rocks at Ghost Ranch

Who knows what other incredible finds remain hidden in the more recent deposits on the vast mesas of the Ghost Ranch and nearby areas.  More recent deposits from the Jurassic period (white sandstone above the red Triassic layer)  have yet to be excavated.

 

the snake that plays “possum”

While looking for Sandhill Cranes and warblers out at Sherburne National Wildlife Refuge the other day, we ran into a field biologist from the Department of Natural Resources who was releasing an Eastern Hognose snake.

The snake had just been implanted with a location transmitter that will allow DNR biologists to track this animal and find out more about its home range and preferred habitat.

This snake had just been implanted with a very small location transmitter that will allow DNR biologists to track this animal and find out more about its home range and preferred habitat.  This is apparently a large size for a hognose snake.

Their heads might look small, but Hognose snakes can engulf a large leopard frog or a mouse without the use of poison fangs or constriction. A set of fangs at the rear of their mouth may help them hang on to their prey as they swallow. Eastern Hognose snakes prefer toads to frogs, though.

Hognose snakes are name for the peculiar scales that give the tip of their snout a shovel appearance.

Hognose snakes are named for the peculiar scales that give the tip of their snout a shovel-like appearance.  They use their shovel-snout to dig into sandy soil and loose litter, either looking for prey or trying to escape predators.

Even though they possess fangs, they are not aggressive and rarely bite when provoked. Instead, they try to bluff their way out of confrontations with potential predators. The first line of defense is to mimic the behavior of a puff adder by coiling up, inflating and flattening their neck, raising their head like a cobra and hissing as violently as a small snake can manage.

If that doesn’t scare off the would-be predator, the snake immediately tries to play dead by rolling on its back, emitting foul odors from its scent glands, excreting feces, opening its mouth widely in a death pose, and even spurting out a few drops of blood. Some predators won’t try to eat dead prey, so they might give up on the snake as a meal.

This Hognose snake tried to be more convincing by regurgitating its last meal -- a frog.

This Hognose snake tried to be more convincing by regurgitating its last meal — a frog.  Photo by Benny Mazur from Toledo, OH. [(http://creativecommons.org/licenses/by/2.0)%5D, via Wikimedia Commons

They will remain in this “death pose” for 10-15 minutes, watching the predator with their unblinking eyes.  If righted, they will immediately roll over again, “playing possum”, just like the mammal for whom the term was coined.

playing-possum-Wikipedia

An Opposum “playing possum” . From Wikipedia, http://en.wikipedia.org/wiki/Opossum

Island rules – part I

Island visitors are often struck by how large some animals get compared to their mainland ancestors: flightless (extinct) dodos (a pigeon!) on Mauritius, giant hissing cockroaches on Madagascar, Komodo dragons on Indonesian islands, giant tortoises on the Galapagos, to name a few.  And Puerto Rico has its “giant” land iguanas, which lay around on sand or shore, unintimidated by human presence.

Head to tail, these land iguanas may stretch more than 3 feet, and they can move surprisingly fast when they want to.

Head to tail, these land iguanas may stretch more than 3 feet, and they can move surprisingly fast when they want to.

Several years ago, I remember a particular iguana that had specialized in stealing food from beach picnickers.

Several years ago, I remember a particular iguana that had specialized in stealing food from beach picnickers and terrorized my daughter into dropping her cookies.  However, this guy paid no attention to us, but was on a mission to somewhere.

But not every species that manages to find an island home grows into a giant, and thus Island Rule #1:  small-bodied species tend to get larger on islands while large-bodied species tend to get smaller (depending on the existing competition for food there and who got to the island first).

In particular, large-bodied herbivores (e.g., elephants, hippos, deer) develop into dwarfs of their mainland ancestors, and relatively quickly — within just 5,000 years in some cases. This makes sense because there simply wouldn’t be enough food on an island to support a population of large-bodied, warm-blooded, leaf eaters.

Case in point — the Key Deer in the Florida keys are about 1/2 the size of their White-tailed ancestors.  Food is limited on the key islands, and deer don’t seem to be great swimmers.

Full-grown Key Deer are about the size of a 6 month old White-tailed fawn.  Photograph taken on Big Pine key, near Marathon, FL.

Full-grown Key Deer are about the size of a 6 month old White-tailed fawn. Photograph taken on Big Pine key, near Marathon, FL.

Gigantism occurs most often on islands where there are no mammalian predators, and is more frequent among smaller-bodied mammals (rodents, in particular), reptiles, and some bird species.  However, when an increased body size impacts foraging habits, like flight in birds, or hanging from ceilings in geckos, then food acquisition puts constraints on the increased body size.

Warning to those visiting tropical islands:  watch out for the giant rats!

Fictional, of course.

Fictional, of course.

Lizard hunting

I have often watched herons and egrets stalk fish or frogs along a lake shore but have never seen one hunt for prey on land.  The technique is much the same, but there is an important difference in the approach.

This Great Egret was hunting small Anolis lizards along the rocky outcrops on the top of a cliff.

This Great Egret was hunting small Anolis lizards along the rocky outcrops on the top of a cliff.

The bird walks slowly with its neck very outstretched, often vertical, until it spies a lizard basking on one of the rocks.  Then it begins to rock its neck slowly back and forth in a sinuous curve, slowly lowering its head, until finally close enough to make a grab (Sorry, but the fence obscured my photos of all of this).

One of many Anolis lizard species, about 3inches in length.

One of many Anolis lizard species in Puerto Rico, this one about 3inches in length.

This particular Egret enjoyed several tasty lizard bites before moving on to other hunting grounds.

Its graceful, upward flight allowed me to get several photos as it flew off.

Its graceful, upward flight allowed me to get several photos as it flew off.

Great EgretGreat Egret

Fall in the foothills

The foothills of the coast range of Northern California are colored green and gold, but are so dry right now, they look like they might combust at any moment. With rain relief still several months away, it is a challenge to survive here.

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The creeks are dry, the vegetation is crispy, flowering plants are in short supply, even the grasshoppers have deserted these drying hillsides, but a few species hang on.

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Western fence lizards were actually numerous, sunning themselves on the trail, waiting for some unlucky insect to stroll by. There is an inverse relationship between incidence of Lyme disease and the number of fence lizards in an area. Apparently, ticks that carry the Lyme disease causing bacterium are cleansed of their parasite by some factor in the lizard’s blood, and these lizards are a favorite target of the ticks.

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Acmon blue butterfly, which looks like our eastern tailed Blue, thrives in dry, weedy, desert and prairie landscapes. This male hovered over the few remaining flowers of a shrub on the hillside before fluttering off to look for food or females. The caterpillars of this species have a mutualistic relationship with ants, who protect them from predation in return for a little honeydew excretion.

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California Towhees were hiding in the shade during the midday heat. This is the signature avian species of the California chaparral community, easily recognized by its uniform brown color, longish tail, and peculiar “double-scratch” foraging tactic. When feeding among dry leaves, towhees lunge forward and quickly hop backward to uncover seeds or insects hiding in the litter. They build their nests in dense thickets of poison oak, which would certainly keep me from bothering their eggs and chicks!

Mother-to-be

Daily thunderstorms, power outages, lightning strikes, flooding — welcome to summer in MN.  I haven’t had any power at my house for three days, so I am excerpting photos from co-blogger (daughter) Alison for this post.

On Tuesday, Alison found a strange new rock in her garden and wondered where the kids had found it.  On closer inspection, the rock had a head with a wire wrapped around it.

Rainstorms flooded the wetland behind her house and a big mama snapper moved up into the yard looking for a sandy beach.

Rainstorms flooded the wetland behind Alison’s house and a big mama snapper moved up the creek into the yard looking for a sandy beach.

The wire turned out to be the antenna of a radio transmitter attached to this 18 inch diameter Snapping Turtle.  Someone at the Department of Natural Resources is probably interested in this turtle’s movements.

Snapping Turtles can be aggressive if you try to pick them up.

Snapping Turtles can be aggressive if you try to pick them up.  Unlike other turtles, snappers cannot fully retract their head into their shell, and will snap their jaws at whatever threatens them from the front.

Peak egg laying season for snapping turtles is June and July, and some females will disperse as much as a half mile overland from their pond or lake to find an appropriate place to lay their large clutch of eggs.

Heading into the garden to find a good spot to lay her eggs.

Heading into the garden to find a good spot to lay her eggs.

Not the right spot, and neither were three others she tried.

Not the right spot, and neither were three others she tried.  They must have some pretty good sensors on those hind limbs that can detect soil type as they dig.  After trying several times to find a good spot, she gave up on this yard and moved on to another one.

Suitable nest sites are open and sunny, with damp but well drained soil.  Snapping turtles commonly use sandy banks and fields, but might even use the side of a gravel road or a lawn.  After finding the right soil and excavating a deep cavity, the female may deposit 10-100 ping-pong ball shaped eggs, covering each with the sandy soil as it is laid.  The embryos require about 2-4 months to develop (depending on the temperature).  During a cool summer, like the one we’re having this year in Minnesota, that means the hatchlings would not emerge until September and would probably remain in the nest all winter.

Temperature is a key factor in development time of all reptiles, and is also important in determining the sex of the hatchling.  Cool temperatures might favor the development of one sex, warmer temperatures the other sex.  The gradient in nest temperature from the top (warmer) to the bottom (cooler) thus insures that a mix of the two sexes will be produced.

In the alligator snapping turtle, more males develop at moderate temperatures than very cool or very warm ones.  But temperatures at which maleness is determined varies among species.  From:

In the alligator snapping turtle (bottom left), more males develop at moderate temperatures than very cool or very warm ones. But temperatures at which maleness is determined varies among species. From: Developmental Biology, Scott F. Gilbert,  2000.

Snapping Turtles might be invading your backyard right about now, but it’s best to just leave them alone — they might decide not to stay there, anyway.

The biota of Antalya province

We did see a variety of fauna and flora in our treks among the ruins of southern Turkey, but without appropriate field guides, I don’t know exactly what we were seeing.

An assortment of invertebrates…some bright, beautiful, and strange.

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Some reptiles in unexpected places, sunning among the ruins…

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Birds were shy and hid in the bushes. This jay came down out of his tree to get a drink; it’s hardly a photogenic shot, but I’ll take what I can get.

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Goats were as common on the coastline shore as the cats were in the ruins at Ephesus and in Turkish cities. They have eaten whatever is edible and left a highly overgrazed landscape in many places. What I learned from watching their early morning activities is that goats can survive by drinking seawater.

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Lastly, a look at the chaparral vegetation of this region.

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Leapin’ Lizards

Some like it hot, and that includes Nevada lizards. It was 99 F air temperature in the desert outside Fallon today, but felt much hotter with the sun beating down on a bare head, and yet, the Zebra tailed lizards were frisky in the afternoon sun.

I haven’t tried to stalk one of these lizards for about 40 years, but they seem to be just as tame now as they were then.  We could walk as close as about 4 feet, reach over and drop a noose of fishing line around their heads, pull it tight, and grab the snared lizard for body temperature measurements.  When they are cool, they are dark on top to maximize heat gain from the sun.

As they heat up, the back skin becomes a mottled gray.  The extremely long toes enable them to stay on top of the sand surface as they run.  And are they ever speedy!  If you can manage to follow them through the desert brush, you might be able to wear them out as they sprint repeatedly away from you 50-100 meters a time.  Chances are you will get overheated before they do.

I have measured body temperatures in excess of 44 Centigrade (111 F) in Zebra tailed lizards in the middle of the day. Why would any sensible lizard be out in the middle of the day in a Nevada desert?

To avoid these guys, the Blunt-nosed Leopard Lizard. Like most other desert dwellers, leopard lizards avoid the crushing heat of the mid-day sun.

These lizards are stealthy stalkers, who hide beneath bushes, dart out and grab unlucky passers by, which might be insects or small lizards.

Big heads, large mouths, and sharp little teeth and toe nails help them grab their prey.

And they do a pretty good job of color matching their background when they need to.

These two lizard species are perfectly adapted to the searing heat and aridity of the northern (Great Basin) desert.

Wonderstone Mountain

I first visited Wonderstone Mountain (or Rainbow Mountain as it is sometimes called) 40 years ago when my husband and I lived in Fallon, Nevada.  Back for a visit today, we were pleasantly surprised that not much had changed in the intervening time (except for a lot of ATV trails through the area).

Wonderstone is a rock that is hydrothermally altered by volcanic fluids so that minerals like iron and manganese impregnate the rock forming colorful bands of white, yellow, red, orange, and purple.  The mountain is basically a huge pile of fractured wonderstone exposing a variety of colorful patterns.

Where the rock washes downhill and onto the desert floor, it can form a colorful “pavement”, in which the sand is hard packed between the rocks, almost as if it was roadbed.

Horned Lizards and Fence Lizards blend into this background quite well, and usually aren’t seen until they move.  When they first emerge in the morning and temperatures are cool, they bask on dark colored rocks and melanin pigment granules dispersed in their skin cells absorb heat.  Later in the day when it is hotter, the pigment granules condense together in the skin cells and the lizards appear grayer and lighter in color, reflecting more of the light and heat that hits them.

Photo from http://www.dipity.com/tickr/Flickr_horned_lizard/

This is as desolate an area as you are likely to come across, even for Nevada.  At this point in the summer, even the insects have quit trying to eke out a living here.

The only evidence of life I saw at Wonderstone Mountain today was the recent burrow excavations of the local Kangaroo Rats, and even they are probably hunkered down in their burrows waiting for cooler days.