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Old 04-04-2010, 11:20 PM
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Default Spring is Sprung!

The trees haven't leafed out yet, but daytime temperatures are up into the 60s and it generally remains above freezing at night, so Spring is definitely on its way!

Last Friday afternoon, I went out to a nearby natural area to look for interesting wildlife. I broke out the hip waders and explored some of the vernal pools. A vernal pool is a temporary body of water that forms in the Spring as low-lying areas fill with water from the combination of Spring rains and melting snow. Since these pools generally dry up by sometime in the Summer, they don't support fish populations. This makes them near-ideal breeding sites for various amphibian species, since there are no fishes present to prey upon their eggs or young. Of course, there are dangers involved in breeding in temporary pools.

Most amphibians, of course, lay eggs that do not have waterproof shells. Accordingly, the eggs must be laid in water -- or at least in moist environments -- in order to prevent fatal dehydration. The larvae that hatch from the eggs have gills and breathe water -- these are, of course, the familiar tadpoles if they're the young of frogs or toads. (Larval salamanders generally look like miniature versions of adults, except with prominent gills.) In most amphibian species, the larvae eventually grow lungs and move onto land.

Well, sort of, anyway. Since amphibians don't have waterproof skins, even the adults are almost always found in wet environments, and they generally live in or near water.

Anyway, the upshot of this is that the strategy of breeding in vernal pools has some advantages (namely avoidance of piscine predators), but it's also a somewhat risky strategy. If the pool dries up before the larval amphibians living in it have grown lungs and become semi-independent of water, they'll die. Accordingly, larger species like Bullfrogs (Rana catesbeiana) generally don't breed in vernal pools; it takes 2 years for a bullfrog to go from egg to air-breathing adult.



So anyway, virtually all of the snow had melted by last Friday, except for a few patches here in there in the deeper and shadier parts of the woods. Similarly, virtually all of the ice had melted off the ponds and lakes.

As I waded into the pool to see what I could find, Western Chorus Frogs (Pseudacris triseriata) were calling like mad. The volume of sound these tiny frogs can produce is simply astounding, and there were so many calling that the combined din was almost deafening. The surrounding woods were reverberating with their "cree-ee-ee-ee-eek! cree-ee-ee-ee-eek! cree-ee-ee-ee-eek!" calls. (The call of a western chorus frog is often described as sounding like the sound made by a comb when you run your fingernail along it.)

Several Wood Frogs (Rana sylvatica) were calling as well. Wood frogs are among my favorite frog species, so I was happy to see and hear some of them. They have particularly unique calls, which make them all the more interesting; the males have gutteral calls that sound something like the quacking of ducks. So, if you find yourself in the northern woods in the very early Spring and you hear what sounds like ducks quacking in the woods, chances are good that you've found some wood frogs.

I was hoping to find some Spotted Salamanders (Ambystoma maculatum), but no such luck.


Wood frogs, western chorus frogs and spotted salamanders are known as "explosive breeders." All of the wood frogs (or spotted salamanders, etc.) in an area will gather at the same time and breed all together. This breeding period is amazingly brief -- they may get together and call for only 2 or 3 nights, and then they're done. Unlike most other frog species, wood frogs (as the name kind of implies) don't live in or near water. Instead, they can usually be found in the leaf litter of moist northern forests. Their brown coloration makes them very well-camouflaged against dead leaves, and so they're practically impossible to find outside of the breeding season.

But for a few days in the late Winter/early Spring, they come together for breeding. They'll gather in vernal pools and the males will give their duck-like "quacking" calls to attract females. (Females generally choose the biggest and presumably the healthiest males for breeding; since the pitch of a male's calls are indicative of his size, this is how the males "advertise" their suitability as mates to the females.) For those brief few days while they're breeding, the frogs tend to have one-track minds. I've walked up to vernal pools with calling wood frogs in them, making no effort whatsoever to hide my presence, reached down into the water to pick up a frog, examined it, and then set it back in the water -- and it goes right back to calling, as if nothing had happened. They're so busy trying to attract mates that they ignore practically everything else.

During that brief frenzy of breeding, the frogs produce enormous numbers of eggs. Then, as suddenly as they appear, they simply ... vanish. Finding a wood frog outside of the breeding season is practically impossible, in my experience.

As you might expect, given that wood frogs often breed while there's still snow on the ground, and that the pools they breed in are often still half-frozen, wood frog eggs are quite resistant to cold. (So are the eggs of spotted salamanders.) On several occasions, I've seen wood frog and spotted salamander egg masses in some pool that was completely covered by ice. So long as the eggs on the bottom don't actually freeze, though, they'll be fine.

In a few days, the tadpoles hatch. As you'd expect, the tadpoles grow very quickly, and they metamorphose into little frogs in just a few weeks' time. (They have to -- the pool will probably dry up by late Summer, so if the tadpoles are to survive, they must mature quickly.) The little frogs disappear into the forest, and they don't come back to water until the next year's breeding season.


Because the frogs breed so early in the season, most of the animals that might eat them or their eggs aren't active yet. So, even though they run the risk that the adults and/or the eggs will be killed by a cold snap, it's apparently worth it to avoid predators like snakes, most of which won't be active for several more weeks.


And because they breed explosively, they can "swamp" whatever predators might be present. Lots of plants and animals are explosive breeders like this. They produce all of their eggs/seeds at once, and in huge numbers, and then go for long periods of time before they breed again. Since so many eggs/seeds are produced in a very short period of time, potential predators are "swamped" and can't possibly eat them all. (If the same number of eggs or seeds were produced over a longer period of time, the predators would have plenty of time to eat most or all of them.)


A lot of plants breed explosively as well. Many oak trees (genus Quercus), for instance, are explosive breeders. Oak trees will go for years with very little acorn production, and then one year all of the oaks in an area will produce huge numbers of acorns. This is called "masting." (It's not entirely clear how the trees coordinate this, but it appears that they "communicate" with each other through chemicals that they release into the air.) With such huge numbers of acorns produced at the same time, there's no way the squirrels and the deer and other acorn-eaters can eat all of them. This ensures that at least some of the acorns will survive to germinate and grow.



Many wildflowers have somewhat similar breeding habits. Lots of wildflowers bloom very briefly in the late Winter/early Spring. Collectively, these wildflowers are called "Spring Ephemerals." (Because they bloom in the Spring, but for only a short time.) By breeding so early, the Spring ephemerals can bloom and produce their seeds before many of the animals that might eat them have awakened from hibernation -- or have returned from their winter migration. Also, by blooming so early, before the leaves have come out on the bushes and trees, Spring ephemerals can avoid being shaded out by taller plants.

So, the late Winter/early Spring -- in that brief window of time between the melting of the last of the snow and the opening of the leaves on the trees -- is a great time to go out into the forest in search of wildlowers. Hopefully, the Spring ephemerals will be blooming soon!




Back in the pool, there were even a few Spring Peepers (Pseudacris crucifer) calling. As the name implies, they have very high-pitched "peep! peep! peep!" calls. Like chorus frogs, they produce an almost-unbelievable volume of sound, considering they're such tiny animals. Unlike the wood frogs and chorus frogs, the peepers have relatively long breeding seasons, so they'll be calling for some time yet.

A Garter Snake (Thamnophis sirtalis) was patrolling the shore. Most likely, he was doing the same thing I was -- looking for frogs. (Garter snakes are usually the first snakes to emerge from hibernation in the Spring, and can often be found weeks before any other snakes are out and about.)





Last night, I went out for a nice walk. It was a lovely evening to be out, as it happened. The frogs were calling lustily, and it was a moonless night; the sky was absolutely clear, with the stars glinting overhead and the Milky Way glowing softly overhead. (You need a pretty dark sky -- well away from artificial lights -- in order to be able to see the Milky Way.) The constellations Canis major, Orion, Cassiopeia and Ursa Major were all clearly visible, and even the Pleiades (a faintly-visible star cluster in the shoulder of Taurus) were easy to see.

A few chorus frogs and wood frogs were still calling in the vernal pools, but they've mostly gone back into the woods already. But the spring peepers were more than making up for them, and the night was simply alive with their calls. In a larger pond, a couple of Northern Leopard Frogs (Rana pipiens) were calling. Unlike the chorus frogs and wood frogs, the larger leopard frogs typically breed in more permanent bodies of water. (It was surprising to hear them calling this early in the season, but I guess these guys were wanting to get an early start.)

Northern leopard frogs are sometimes called "Meadow Frogs" because, instead of staying in or very near water like most other frogs, they're typically found in grassy meadows outside of the breeding season -- sometimes surprisingly far from water.

A lonely American Toad (Bufo americanus) was calling, too. It's a bit early for American toads, but they, too, are early Spring breeders.



In addition to the frogs and the clear night air, I found the skull of a Raccoon (Procyon lotor) in one of the pools. The bottom jaw was missing, and several teeth were missing from the upper jaw. The skull itself was in good shape, though, and showed no obvious signs of trauma. I considered taking it home for further examination, but decided to leave it where I'd found it.

Coincidentally, I heard some rustling a in a nearby tree just a few minutes later. I turned on my flashlight and shone it up into the tree to see a raccoon looking at me. Later in the night, I heard some squalling back in the woods behind the house -- sounds like a couple of male raccoons got into a fight, perhaps over a female.


More rustling in a nearby tree. Again I whipped out my flashlight, and this time there was a Virginia Opossum (Didelphis virginiana) looking back at me.

An Eastern Screech Owl (Megascops asio) called softly from somewhere nearby. It's my favorite owl species, and I tried to find it, but to no avail.



Speaking of mammals, and of seasonal changes, the Deer Mice (Peromyscus maniculatus) seem awfully active lately! It's lucky for them I'm a biologist and don't like to kill animals if I can avoid it. I have several "live traps" that I've used for monitoring small mammal populations. Anyway, now that the weather is warming up, they're apparently becoming more active. And apparently, there's no way to keep the little buggers out of the house. I've trapped 6 of them in just the past couple of weeks. I caught 3 of them last Friday night alone! They're cute little things with their big black eyes, but they'd better hope they don't get me sufficiently annoyed at their constant intrusions that I decide to take lethal measures against them! (I carry them some distance away from the house and release them, with a stern admonition to not come back. I hope they're listening!)

I seem to be making some headway, it seems. I've only caught one during the past week. So I'm hoping that trend holds. Fortunately, it's Peromyscus I'm dealing with here, and not "House Mice" (Mus musculus). House mice are non-native species (they're native to Europe and Asia) and can be very ecologically destructive here in North America. I'd be a lot less reluctant to use lethal trapping methods against house mice.


Anyway, Spring is definitely springing!


Cheers,

Michael
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Last edited by The Lone Ranger; 04-04-2010 at 11:40 PM. Reason: Added links to calls
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  #2  
Old 04-04-2010, 11:55 PM
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Default Re: Spring is Sprung!

The bumblebees are out in full force already in my back yard. They love hovering around the deck where all my herbs live. I almost felt bad harvesting the sage blossoms before they opened because the bees enjoy them so much. Sorry gais, but that's working sage; if I let it go to seed I'll get many fewer leaves to nom.
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Old 04-05-2010, 12:08 AM
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Default Re: Spring is Sprung!

The frogs here, Pacific Treefrog (Hyla regilla), have been busy calling for mates all month.

I often forget how early the start calling and it always surprises me, as I associate them with spring.
I've got a native creeping huckleberry that is blooming too.
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Old 04-05-2010, 12:23 AM
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Default Re: Spring is Sprung!

I love Hyla regilla!

As an aside, this is the only species of frog native to North America that has a call that sounds like "ribbit." And they're found only in the western U.S. and northwestern Canada.


So why is it that practically every television show or movie made in the U.S. uses the call of Hyla regilla to represent the call of a frog -- even when the show/movie is set someplace where Hyla regilla doesn't live?

I can only assume that it's because most such movies/television shows were filmed in California, at least originally -- and at some point, somebody went to a nearby wetland and recorded the calls of Hyla regilla for use as "generic frog calls". And movies and television have been using these recorded calls ever since.

So pervasive has been the influence of American-made movies and television that even lots of people from outside North America think that frogs generally go "ribbit" -- even though it's just one species of frog native to the western U.S.


Cheers,

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Last edited by The Lone Ranger; 04-05-2010 at 12:36 AM.
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Old 04-05-2010, 12:57 AM
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Default Re: Spring is Sprung!

Here's a couple of sound recordings of Hyla if anyone's curious.

Sounds of Pseudacris regilla - Northern Pacific Treefrog

I have a tape recording of some Balinese frogs, but I can't find anything about them on line.
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Old 04-05-2010, 01:07 AM
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Default Re: Spring is Sprung!

It's Autumn, people! Autumn!
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Old 04-05-2010, 01:55 AM
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Stop being so upside down all the time.
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Old 04-05-2010, 02:09 AM
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Default Re: Spring is Sprung!

That's what they get for mining all the Upsidaisium.
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Old 04-05-2010, 02:28 AM
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Stop being so upside down all the time.
From where I'm standing you're the ones that are all upside down. How do you stop falling off?
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Old 04-05-2010, 06:11 AM
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Glue, made from horses.
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Old 04-05-2010, 06:15 AM
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Pure animal magnetism.
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Old 04-05-2010, 06:16 AM
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:cheesywink:
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Old 04-05-2010, 06:28 AM
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Pure animal magnetism...
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...made from horses.
:lol:
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Old 04-05-2010, 07:54 AM
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Default Re: Spring is Sprung!

Unfortunately even living in a green part of SF we don't get many animals besides the occasional city raccoon (just cause they are gay SF raccoons doesn't mean they don't carry around a switch blade and they will fight for their McDonald's wrapper).
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The bumblebees are out in full force already in my back yard.
For the last month or so we have been getting some awesome huge and fuzzy bumble bees out on the coast lazily buzzing the flowers. They have that same kind of stumble that the surfer dudes do.

This makes me want to be back in the foothills where I used to live. We would get those little pacific tree frogs stuck to our glass backdoor. Just turn the florescent outdoor light on to get the bugs flocking and the door was covered with them. Unfortunately it meant we had to watch the door cracks when coming in or out to try to minimize the number of squished froggies on the door jam.
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Old 04-05-2010, 01:08 PM
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A new thread from TLR. Better than National Geographic.
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Old 04-05-2010, 03:52 PM
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Default Re: Spring is Sprung!

On Saturday I saw my first Bluebonnets of the season. Just a tiny little patch, but I hope soon we will have fields of them.

Then yesterday I saw the first hummingbird since it has become warm. I only saw him for an instant as he buzzed down looking at me before darting up over the house. I think it was a white eared hummingbird but again I only saw him for a second.
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Old 04-05-2010, 05:01 PM
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Quote:
Originally Posted by The Lone Ranger View Post
I love Hyla regilla!

As an aside, this is the only species of frog native to North America that has a call that sounds like "ribbit." And they're found only in the western U.S. and northwestern Canada.
The frogs (toads?) down by the pond I walk past on the way to work were going more like 'wurp', if I had to call it anything.

There were a lot of frogs, and it was a little bit uncomfortable to tip-toe through a horde of frogs doing the things frogs do in frog-mating season. Especially since they all were well camoflaged like rocks or leaves on the path, so I'd frequently find myself nearly treading on a pair of them and having to divert my foot at the last moment.
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Old 04-05-2010, 05:17 PM
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Default Re: Spring is Sprung!

Doesn't seem much like spring here yet. We got snow dumped on us again over April Fools. Some mornings you can hear a lot of birds but I haven't seen many insects or new growth yet.
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Old 04-05-2010, 07:07 PM
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I actually saw some honeybees in the backyard last week. Real, no-foolin' honeybees. That probably doesn't sound too remarkable, but it may be the first time I've seen them since moving here 3 years ago. Plenty of those goddamned yellowjackets that need to die die DIE, but no honeybees. I miss the big ol' lazy bumblebees, too.
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Old 04-05-2010, 07:12 PM
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Quote:
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Quote:
Originally Posted by livius drusus View Post
The bumblebees are out in full force already in my back yard.
For the last month or so we have been getting some awesome huge and fuzzy bumble bees out on the coast lazily buzzing the flowers. They have that same kind of stumble that the surfer dudes do.
That reminds me that when my nephew was a little tyke he used to call them "bungle bees". :aww: :giggle:
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Old 04-05-2010, 08:08 PM
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Default Re: Spring is Sprung!

I was stalked by bumblebees at my parents' home yesterday. The critters apparently loved the scent of my hairspray or something.
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Old 04-05-2010, 08:27 PM
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I went out for another walk last night, right after a brief rainfall. Since it had just stopped raining, and the rainfall had been very brief, earthworms were coming up out of the soil all over the place. If I were a fisherman, I could've gathered all the bait I could want in just a few minutes' time.
It's amazing how noisy some animals can be. I could easily hear the worms pushing aside leaves as the came up out of the soil and onto the surface, and the sound of worms emerging from the soil was all around me. Pretty neat, actually.

No wood frogs were calling last night, so they may be done for the season, alas. A few optimistic chorus frogs were still calling, though. The spring peepers were in full voice though, and the woods rang with their calls. Several leopard frogs and American toads were calling, too. I saw some Green Frogs (Rana clamitans) in the water, but they won't start calling for awhile yet -- not until the water gets somewhat warmer.


A soft yellow-green glow in the leaves caught my eye. It turned out to be a "glow worm." A larval firefly, actually, probably in the genus Lucidota, perhaps Lucidota atra.

As in quite a lot of insect species, larval fireflies are wingless and specialized for eating, whereas the winged adults are relatively short-lived and focused on reproduction. In some firefly species, the females remain wingless throughout their lives, and they use their bioluminescence to attract the attention of males flying overhead. (In other species, the females grow wings too, and the males and females court each other in the air.)

Given that it's often the case that many different firefly species occupy a given area, there must be some way for fireflies to identify each other by species, so as to avoid attempting to mate with a member of a different species. Males of a given species flash their signals in distinctive patterns, and females will give corresponding signals to attract males of the appropriate species.

Have I mentioned that larval fireflies are fiercely predatory? The fireflies' tissues contain noxious chemicals, and most would-be predators (toads, for example) quickly learn to leave them alone. Apparently, the larval fireflies' glow makes it easy for predators to recognize and avoid them.


So, most firefly species are predatory in the larval form, and many are predatory as adults, too. And females use their flashes to lure amorous males to them.

You can probably guess where this is going.

Firefly femmes fatales in the genus Photuris, when they spot a male in the genus Photinus flying overhead, will switch from their normal flashing pattern (which lures in male Photuris, but not male Photinus) to the flashing pattern of a female Photinus. The male Photinus flies down in anticipation of sex -- and promptly gets attacked and eaten.



On the way back to the house, I saw something odd in a tree. As it turned out, it was a balloon. Attached to it was a note from a "New Life Christian Center." The note gave a telephone number and asked the finder of the balloon to call that number. It also gave a mailing address. Looking up the address on "Yahoo maps," it seems that the balloon traveled about 85 miles in an east-northeast direction before alighting. The first line (actually the second line; the first is a Bible verse) says: "My Name Is Amanda." Judging from her handwriting, Amanda is probably about 10 years old.

I don't think I'll call the number, but I think I'll mail a short letter to the address. I know that if I'd done something like that, I'd want to know how far the balloon went, in what direction, and so forth. So I'll give a brief description of the circumstances under which I found it.

If she responds, I may feel inclined to point out that I really wish that people wouldn't release balloons like that, though. As fascinating a thing as it is to do, if the balloon should travel far-enough to wind up in the ocean, it could be ingested by a sea turtle or a seabird such as an albatross or gannett. (Sea turtles and seabirds often ingest balloons and other plastics, apparently because they mistake them for jellyfish.) Since the material of the balloon is indigestible, it blocks the animal's digestive tract, dooming it to a slow and presumably painful death.



Cheers,

Michael
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  #23  
Old 04-06-2010, 03:59 AM
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Default Re: Spring is Sprung!

It has been a nice, warm, and very sunny day today. It seems a shame to waste such a day, so I got out for a bit after my last class of the day. As it happens, there's a nice arboretum just a few minutes' drive away, so I went to have a look around.

There were quite a few lovely specimens of Homo sapiens coedicus wandering about the area. As best I could tell, they had all shed their heavy winter pelages for somewhat less insulative coverings.


There is a low-lying, swampy area at one end of the arboretum, and a couple of hundred yards up a gentle slope is an artificial pond. There were some kids excitedly talking about a "huge turtle," so I went to investigate. As it turned out, a Snapping Turtle (Chelydra serpentina) was making its way out of the swamp, apparently heading for the pond. I warned the kids not to mess with the turtle, as snapping turtles are quick to defend themselves when on land (they tend to be surprisingly timid when in the water though), and can give a nasty bite. Supposedly, an adult snapping turtle can amputate a person's finger with a bite, though I know of no actual instances of that happening. (Though I once had one take a chunk out of a leather boot I had been wearing at the time. I'm just as glad it wasn't my foot ...)

This particular turtle certainly wasn't fully grown, but it was more than large enough to have delivered a painful bite. Rather than risk someone else coming across the turtle and perhaps harming it -- and/or being harmed by the turtle -- I decided it would be best to speed it to its destination. So I showed the kids how to safely pick up a snapping turtle and carried it to the pond. They seemed impressed.



On the other hand, I sometimes worry about what kind of precident that sort of thing sets. I remember a General Zoology course I taught once in North Carolina. I took the students outside whenever possible, and would catch snakes, lizards, frogs, fishes, crayfishes, insects, etc. to show to them. This was all well and good, because I certainly wanted to show the students how interesting the animals in question were, and to dispel some negative stereotypes.

However, one young woman caught a large Fowler's Toad (Bufo fowleri) and announced that she was going to keep it as a pet. I told her that I really wished she wouldn't, and that it'd be better to leave the animal in its natural habitat. "But you catch animals all the time," she protested. I pointed out that I catch animals to show to students, and that afterwards I'm always very careful to return them to exactly where I found them.



Anyway, some crocuses and Forsythia were just coming into bloom near the main entrance to the main entrance to the arboretum, as was a lovely Star Magnolia (Magnolia stellata).

But those don't really count, as far as I'm concerned, since they're non-native cultivars.


Speaking of which, I noticed that the name tag on one of the trees identified it as an Eastern Redcedar (Juniperus virginiana). That's all well and good, except that the tree was quite clearly a Western Redcedar (Thuja plicata), a species with a distinctly-different leaf shape and growth form. I'll have to make a mental note to find somebody in charge of the arboretum and mention that to them.



After releasing the snapping turtle, I wandered around the pond for awhile. Water Striders (genus Aquarius, most likely) "skated" across the surface.

A water molecule is, overall, electrically neutral. But because the electrons are not "shared" equally between the two hydrogen atoms and the oxygen atom that make up a water molecule (the oxygen tends to "hoard" the electrons), a water molecule is polar. That is, the oxygen atom has a slight negative charge (because the negatively-charged electrons spend proportionately more time in the vicinity of the oxygen atom) and the two hydrogen atoms each have slightly positive charges (because the electrons spend proportionately less time in their vicinity and so can't quite balance the positive charges of the hydrogen atoms' protons).

As a result of the polar nature of water molecules, they tend to be strongly attracted to each other. That's because the partially-negative oxygen atom of one water molecule is attracted to the partially-positive hydrogen atoms of nearby water molecules.

Within a body of water, any individual water molecule will feel no net force due to these attractions, because each molecule is being attracted by surrounding molecules in every direction. And so the forces exerted by all the surrounding molecules cancel out. But for a water molecule at the surface, things are different.

Since a water molecule at the surface is not attracted to the air molecules above it, but is attracted by the water molecules to its sides and beneath it, a net downward force results. This causes the water molecules at the surface to be pulled together, relative to water molecules inside the body of water. Because the water molecules at the surface are thus under tension, we say that the water has surface tension. The surface tension resists penetration, and so anything that's light-enough can literally walk on water.

Water striders have hydrophobic (water-repelling) "hairs" on their legs. Since the water molecules don't stick to their legs, water striders can walk on water. You can, if you're interested, calculate whether or not an animal can walk on water. It's a function of the animal's weight and the amount of its body that's touching the surface of the water.

The actual formula is: .

T represents the surface tension, which resists the animal breaking through the surface of the water. (That's 0.073 Newtons/meter in freshwater.) The letter p represents the animal's density (in kilograms per cubic meter). The letter l represents the length (perimeter) of the animal's body that's touching the water surface, in meters. (The more of the animal's body that's touching the water surface, the more its weight is spread out, and so the less likely it is to break through the surface tension.) The g represents the force exerted by gravity, which is attempting to pull the animal through the surface tension.

If you do the calculations and Je is greater than 1, the animal can walk on water. Oh, what is Je? It's called the "Jesus number." If your Jesus number is greater than 1, you can walk on water.


Why can't large animals walk on water? Because mass (weight) is a cubic function, but surface area is only a square function. This means that as animals grow larger, their weight increases far faster than does their surface area. So only very small animals can possibly have feet that are large-enough relative to their weights to support them on water.



Anyway, lots of water striders were "skating" across the pond. Animals are mostly made of water and organic molecules, and most organic molecules are polar. This means that for a very small animal, like your average insect, water can be very-much like glue. Water striders don't stick to water because of their water-repellent coatings, but most other insects aren't so lucky. So for most other insects, falling onto the surface of a body of water is very much like what we'd experience falling into a vat of warm tar -- escape is all but impossible. Water striders are predators, and they cruise about the surface of ponds and lakes, in search of unfortunate insects that get trapped on the surface.



There were lots of Whirligig Beetles (probably genus Gyrinus) scooting about on the surface of the pond as well. Like the water striders, they have waterproof coatings, and so can move on the water's surface without sticking to it. One thing that makes them interesting is that they have divided eyes -- one half of each eye projects above the water's surface, which allows them to scan for potential predators, while the other half of each eye projects below the water's surface and scans for prey or for predators approaching from below. (The beetles dive for prey.)

Like water striders, whirligig beetles can push against the water's surface to "skate" along, much like an ice skater does.


Speaking of beetles and surface tension, my favorite example is Rove Beetles (family Staphylinidae). Some rove beetles have a really neat trick, should they happen to fall onto some water. To escape the sticky deathtrap, the beetle secretes a surfactant from openings in its abdomen.

A surfactant is a substance that reduces surface tension. (Detergents are surfactants.) When a rove beetle secretes surfactant from its abdomen, this lessens the surface tension behind it, but not in front of it. This creates an unbalanced force and the beetle is propelled by it across the surface of the water. The beetle can keep this up until it runs out of surfactant; hopefully, it'll hit dry land before that happens.



Painted turtles (Chrysemys picta) were swimming in the pond and basking on logs that protruded from the water. Green Frogs (Rana clamitans) were sitting on the shore or floating in the shallow water near shore.


I wandered down to the swampy area, and several male Red-Winged Blackbirds (Agelaius phoeniceus) were calling from the dead stems of last year's Cat-Tails (Typha latifolia).

Red-wings are interesting insofar as they have very different breeding behavior from most other songbirds. Males arrive in swampy areas during the early Spring and begin setting up territories. Swamps tend to have lots of food available for songbirds, and a good territory can easily support several nests. What's more, in a good territory, a female can easily find enough food to feed her offspring, even without help from her mate.

Consequently, a male who manages to secure an especially choice territory may have 5, 6 or even more females nesting in his territory. (Some especially successful males have had as many as 15.) He mates with each female in his territory and then zealously defends the territory against all intruders. Other than defending against intruders, he plays little or no role in raising his offspring.


A pair of White-Breasted Nuthatches (Sitta carolinensis) flew past and alighted on a nearby tree trunk. They have this neat habit of landing near the top of a tree and then methodically moving down the tree trunk (upside-down), while prying the bark aside in search of hidden insects.


In the wet ground near the edge of the swamp, some Eastern Skunk Cabbage (Symplocarpus foetidus) was just coming into bloom, filling the nearby air with its distinctive stench. (It isn't called "Skunk Cabbage" for nothing!) The plant begins to bloom in the very early Spring, often while snow is still on the ground. The combination of its heat-absorbing dark coloration and its very high metabolic rate (for a plant) means that it can actually melt the snow around it. The scent is somewhat like that of rotting meat, which attracts the flies that pollinate its flowers.


There was some movement in the cattails, and a Garter Snake slid into view. It froze when I moved to get a better look at it, but eventually continued on its way when I made no threatening movements.


Some sudden movement in the water turned out to be a Muskrat (Ondatra zibethicus). It surfaced, grabbed a cattail stem, and then dragged it under the water. Presumably, it then headed to its den to eat in peace.



Something was thrashing about in the dry leaves nearby; it turned out to be an Eastern Gray Squirrel (Sciurus carolinensis). Despite the common name, this squirrel was actually jet black. Melanism is the exact opposite of albinism. A "melanistic" animal is one that produces an overabundance of the dark pigment melanin and so has very dark skin and feathers (if a bird) or fur (if a mammal).

Black squirrels are actually fairly common in parts of the American Midwest and Northeast, and the dark coloration may be adaptive in colder climates. (It may help them absorb solar radiation more efficiently.) I've heard that black squirrels are actually tourist attractions in some city parks. (Battle Creek, Michigan has a large population of black squirrels, for instance.)


As I moved up and into the woods above the swamp, I noted that a number of deer exclosures had been set up. These prevent the hooved locusts from gobbling up virtually every plant on the ground. What we really need around here are more coyotes, cougars and wolves!

There was a lot more green on the ground in the deer exclosures than there was outside of them. I noticed some Trout Lily (Erythronium americanum) just coming into bloom in one of the exclosures. I may have to return this weekend with my trusty camera.

Some Common Blue Violets (Viola sororia) were also coming into bloom. If the weather continues like this, this weekend might be an excellent time to begin the Springtime routine of tramping through the nearby woodlands at every available opportunity, in search of Spring ephemerals.



When I got back to the lake in the main part of the arboretum, a Tree Swallow (Tachycineta bicolor) was zooming low over the water, dipping its beak downward every now and again to take a sip.


A Bullfrog (Rana catesbeiana) was floating in the water near the shore. It's entirely possible that the frog could have caught and eaten the swallow, if the bird had been sufficiently unwary. (Not that I think the frog's speed and reflexes would have been up to catching a swallow on the wing.) Bullfrogs have been known to (somehow) catch and eat small snakes, mice, and even birds.



Some Song Sparrows (Melospiza melodia) were calling from the nearby trees. A brilliantly-red Northern Cardinal (Cardinalis cardinalis) was calling as well.

Some Blue Jays (Cyanocitta cristata) were calling, too. For whatever reasons, a lot of people don't like blue jays, but they rank as one of my favorite bird species; they're not only strikingly beautiful, they're remarkably intelligent. Most people who live in the eastern half of the U.S. are probably familiar with the blue jay's "jay! jay! jay!" alarm call, but few people realize they actually have lovely singing voices.

As an aside, this might be surprising to some people given that blue jays are well-known for their ability to coexist with humans, but in the early days of this nation, blue jays were noted for their remarkable shyness and their reluctance to live anywhere near human settlements. (Evidently, in the intervening years, they've gotten over it.) This was such a noteworthy trait of blue jays that people who lived out in the country, well away from any sizable settlements, were called "jays." That's supposedly where the expression "jaywalking" comes from -- since, presumably, only a hick (a "jay") wouldn't know how to cross a street properly.



Surprisingly, in one of the trees near the pond, a Gray Treefrog was calling. It's awfully early in the season, but evidently this one was getting an early start. This one was Hyla chrysoscelis, Cope's Gray Treefrog. Cope's gray treefrog and the Common Gray Treefrog (Hyla versicolor) are known as "cryptic species" because, though they often occupy the same area and are impossible to tell apart by sight, they are separate species that do not interbreed. Aside from counting their chromosomes, the only way to tell them apart is by listening to their calls. The call of Hyla chrysoscelis is a fast trill; the call of Hyla versicolor is slower.


Yup, Spring is definitely springing!


Cheers,

Michael
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Last edited by The Lone Ranger; 04-06-2010 at 04:14 AM.
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  #24  
Old 04-06-2010, 04:14 AM
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Dingfod Dingfod is offline
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Default Re: Spring is Sprung!

Quote:
Originally Posted by The Lone Ranger View Post
There were quite a few lovely specimens of Homo sapiens coedicus wandering about the area. As best I could tell, they had all shed their heavy winter pelages for somewhat less insulative coverings.
I observed the same today, much to my delight.

Quote:
Originally Posted by TLR
Anyway, some crocuses and Forsythia were just coming into bloom near the main entrance to the main entrance to the arboretum, as was a lovely Star Magnolia (Magnolia stellata).
These are in bloom here as well. The yard is quite colorful right now.


Quote:
Originally Posted by TLR
But those don't really count, as far as I'm concerned, since they're non-native cultivars.

Speaking of which, I noticed that the name tag on one of the trees identified it as an Eastern Redcedar (Juniperus virginiana). That's all well and good, except that the tree was quite clearly a Western Redcedar (Thuja plicata), a species with a distinctly-different leaf shape and growth form. I'll have to make a mental note to find somebody in charge of the arboretum and mention that to them.
How could they make such a ghastly error?



Quote:
Originally Posted by TLR
Why can't large animals walk on water? Because mass (weight) is a cubic function, but surface area is only a square function. This means that as animals grow larger, their weight increases far faster than does their surface area. So only very small animals can possibly have feet that are large-enough relative to their weights to support them on water.
There is a lizard, basilisk lizards I think, also known as Jesus lizards, that can run on water for a short distance when frightened, but it does it in much the same manner as a snowmobile crossing water, by moving its legs fast enough that it doesn't sink for about fifteen feet, or for about 3 seconds. It then drops to all fours and swims, something the bible didn't say Jesus knew how to do.
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Old 04-06-2010, 04:19 AM
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:lol: "Jesus factor"
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