New backyard bird: Chimney Swift

A bird that's probably familiar to many of you is Chaetura pelagica (Linnaeus, 1758), more commonly known as Chimney Swift. It's been described by Alexander Sprunt (1954) as "resembl[ing] in appearance a cigar on wings" because of its tubular body and long, long wings. Most of the time you see it on the wing, flying overhead chasing down its insect prey, and twittering like mad. It always reminds me of the last line of one of the most famous of Keats's odes, "To Autumn":

Where are the songs of Spring? Ay, where are they? Think not of them, thou hast thy music too,— While barred clouds bloom the soft-dying day, And touch the stubble plains with rosy hue; Then in a wailful choir the small gnats mourn Among the river sallows, borne aloft Or sinking as the light wind lives or dies; And full-grown lambs loud bleat from hilly bourn; Hedge-crickets sing; and now with treble soft The red-breast whistles from a garden-croft; And gathering swallows twitter in the skies.

Keats's swallows are what we call here in the States "Barn Swallows," Hirundo rustica (Linnaeus, 1758). They are the most widespread species of swallow in the world, and they are what the poet saw at dusk on September 19, 1819, as he wrote what was to become the most anthologized poem in the English language. We have Barn Swallows here in Florida, with records in every season for Palm Beach County. We see them gathering in large flocks on our annual trips to the flooded fields of western Palm Beach County in August, and  they are even reported breeding in neighboring Hendry County.

But the bird that occurred today at my house, while it looks largely similar to the swallow through the process known as convergent evolution, is not even closely related to the swallow family. (The idea of convergent evolution is that animals that specialize in similar ecological niches, the way swallows and swifts specialize in catching insect prey on the wing, often evolve similar body shapes. In this case, long, pointed wings and a beak with a large gape. In a more general example, the wing itself evolved separately in the mammalian, insect, and avian groups.)

Chimney Swifts are actually more closely related to the hummingbirds than to the swallows they resemble. This fact has been known at least since Arthur Cleveland Bent's magisterial series on North American birdlife: Life Histories of.... Bent published the volume on Cuckoos, Goatsuckers, Hummingbirds and their Allies back in 1940 as United States Museum Bulletin 176, although most birders with extensive libraries have the Dover edition, which the publisher released in two slim volumes to increase their profit margins. (After starting this post, I found out that the text is available online as well, so you don't even have to go to the trouble of devoting 3 or 4 feet of bookshelf to the printed version.)

Bent writes of the migratory nature of this bird:

From its unknown winter quarters, somewhere in Central America or on the South American Continent, the chimney swift comes northward in spring and spreads out over a wide area, which includes a large part of the United States and southern Canada.

Individually, the swift is an obscure little bird, with a stumpy, dull-colored body, short bristly tail, and stiff, sharp wings, but it is such a common bird over the greater part of its breeding range and collects in such enormous flocks, notably when it gathers for its autumnal migration, that as a species it is widely known.

Does that last sentence remind anyone else of Keats's swallows? Hmmm? Well, never mind, then...

The write-up in Sprunt (1954) and Stevenson and Anderson (1994) updates Bent's "unknown winter quarters" to a locale in the upper Amazon Basin, determined by bird banders in the 1940s, who recovered a few birds banded in Tennessee. According to Sprunt,

The Chimney "Swallow" as it is often and erroneously called, is one of the most familiar birds of the country, as it appears in multitudes about human habitation.... Not the least interesting thing about this very interesting bird was, until recently, the mystery of its winter home. No one knew for certain where it was. Then, in May of 1944, word was received from the American embassy in Lima, Peru, that some bands had been turned in, "secured from some swallows killed by Indians" along the border of Peru and Colombia, some 6 months earlier. Most of the "swallows" were Chimney Swifts and had been banded in Tennessee (F. C. Lincoln, Auk, 61:604, 1944). Thus a mystery was solved and the supposition that some of the birds wintered in South America vindicated.

Bent describes the behavior of this bird in terms of its "curious" relationship to people:

Although the species spends the summer scattered over a large part of the North American Continent, it never, except by accident, sets foot upon one inch of this vast land. The birds build their "procreant cradle" in the chimneys of thousands of our homes and crisscross for weeks above our gardens and over the streets of our towns and cities, yet, wholly engrossed in their own activities far overhead, they do not appear to notice man at all. Indeed, it is easy to believe that the swift is no more aware of man during the summer, even when it is a denizen of our largest cities, than when in winter it is soaring over the impenetrable jungles of Central America.

How do we regard this bird that does not know we are on earth? We are glad to have swifts breed in our chimney; we like to see them shooting about over our heads, and we enjoy their bright voices; yet, do we feel such friendship for them as we feel for a chipping sparrow, for example, which builds sociably in the vines of our piazza? The little sparrow may be wary, and may fly away if we come too near, but at least it pays us the compliment of recognizing our existence. The swift, however, is not even a semitrustful neighbor; it is a guest that does not know we are its host. We may almost think of it as a machine for catching insects, a mechanical toy, clicking out its sharp notes. But let us note this fact. Every ten years or so the swifts do not appear about our house in the spring. Something has gone wrong on their journey northward. Our chimney will be empty this year; there will be no dark bows and arrows dashing back and forth above our roof, no quick pursuits and chattering in the evening. All summer something is lacking because there are no swifts to enliven the season. We realize, now that they are gone, how we should miss their active, cheerful presence, if they never came back again. But we may be sure they will come back--next year perhaps--to visit us again, this most welcome "guest of summer."
I always enjoy hearing them pass about overhead, when I'm gardening or swimming with the kids in the pool. Whenever I hear them twittering, I point it out to the boys. Eric is starting to get mildly interested in it, at least to the extent of agreeing that birds are "so pretty" and their songs are "so nice." Daniel, on the other hand, is absolutely ga-ga over birds, at least the prints of birds that we have hanging on our walls. Speaking of hanging on our walls, I haven't even gotten around to showing you the impetus for this post! For the past couple of days, I've noticed that there is a rather insistent quality to the chittering near our house, and yesterday I heard flapping in our chimney. Could it be? Could our chimney be blessed with a swift family building its nest? I still don't know the answer to that question, but a look up top shows that the possibility certainly exists:

Open chimneys invite Chimney Swifts to move in.

And since our fireplace doesn't have a flue (there's something in there that blocks the rain and catches the leaf litter that blows in, but there is evidently still a large passage through which animals can squeeze), this morning my office was paid a visit by one of the birds itself. Imagine my surprise on entering my little office to hear a flapping inside the room! I saw a little black bird up on top of my tall bookshelves and immediately closed the door to make sure the creature didn't fly into the rest of the house where it might get irretrievably lost or hurt. Then I opened the window, removed the screen, and began trying to herd it out through the opening. Easier said than done. After a few minutes of trying to get close enough to it with the screen in hand so that I could sort of shoo it out, I gave up on the hands-off approach and decided I'd better just let it settle down somewhere while I took a few pictures and thought things through. No sooner thought than done. After I stopped chasing it, it seemed to take some comfort, settling in to a cozy resting place on the top shelf, which, as it happened, is the home of my copies of Bent's fine Life Histories series: Here you can see it clinging to volumes two and three of Cardinals, Grosbeaks, Buntings, Towhees, Finches, Sparrows, and Allies. (Apparently it can't read, or doesn't know its place in the taxonomy of North American bird life!) Eventually I was able to get close enough to it to take a decent portrait: Then, perhaps proleptically encouraged by the words I was soon to read in Bent's write-up of the species ("banders who have handled the birds report that they show little or no fear (or consciousness) of man and appear tame to an extraordinary degree"), I was able to sneak up on it from below and wrap it up in a towel. I was concerned that it would be as nervous and fluttery as it was when I first walked into the room and surprised it, but it went completely still and allowed me to snap a few awkward shots with my left hand, while holding it in my right: Here you can see the bristly tail feathers Bent described, and you can also see how much longer the wings are than the tail. ("Primary projection," that is, the difference between the end of the longest of the innermost wing feathers (tertials) and the end of the longest of the flight feathers (primaries), is a different metric, and is of little use in identifying swifts or swallows because they're always flying so you never see it!) After a couple of clumsy left-handed shots, I took pity on the poor bird and set it on the windowsill and removed the towel, whereupon it instantly sprang into action, whirred once around the tiny courtyard, and hasn't been seen since. References Bent, A.C. (1940). United States National Museum Bulletin 176. Repr. 1964, New York: Dover. Available online as Life Histories of North American Birds. Sprunt, A. (1954). Florida Bird Life. New York: Coward-McCann, National Audubon Society, USFWS and Florida Game and Fresh Water Fish Commission. Stevenson, H.M., and B.H. Anderson. (1994). The Birdlife of Florida. Gainesville: University Press of Florida.  

New backyard bug: Ischnura posita

One thing that I'm really enjoying about the new place is that I've seen several species of damselfly in the backyard in the little more than a year that we've been here. The old place had lots of dragon- and butterflies but, perhaps because there was no backyard pool, there were no damselflies, at least that I recall. So far I've seen a couple of species of Forktail (Ischnura ramburii and I. hastata), a sprite or two (Nehalennia pallidula),  a bluet (Enallagma sp., probably doubledayi) and an unidentified spreadwing species ("documented" by perhaps the worst photo I've ever taken). Today I saw a third forktail species, Ischnura posita, the Fragile Forktail. The male is a very handsome fellow, with stunning green eyes (black on top), a black thorax marked by two interrupted stripes (Dunkle characterizes them as "a a pair of upside-down exclamation marks"), and a long, mostly black abdomen with most segments marked by green rings right where it meets its neighbor: I've been hoping to catch a glimpse of this fellow for quite some time; ever since I got my two damselfly guides this year (the 2011 Paulson guide to Eastern dragon- and damselflies, and the 1990 Dunkle guide to Florida damselflies). It's just a very good-looking bug! Here's another angle for those of you who can't quite get enough of him: Look around your yard; see what you find!

A grasshopper on a leaf is not a leafhopper

After you've seen them a few times, you stop being surprised at where you'll find grasshoppers: crushed gravel roads, up in palmettos, on your pipevines. Still, when they let you approach closely, there's no denying that they're handsome beasts: But no matter where you find them (trees, leaves, gravel), they're still grasshoppers, not treehoppers, leafhoppers, or gravelhoppers. One of these days, I suppose I'll find a real leafhoppper. Trouble is, they're all pretty small, and I'm still barely learning the charismatic megafauna of the insect world (you know, the large showy creatures like butterflies, dragonflies, etc.), so I've probably passed hundreds of them by already... I saw this one last November as we were outside with Eric, enjoying the lovely "fall" weather here in Florida: warm but not hot, breezy but not windy, nice low humidity. I guess there's a reason people all these other people decided to live in Florida, too. Now that we're in the middle of April, the weather is somewhat heavier, with a strong dose of summer in the air.

Small Owls

I'm preparing a slide show for an upcoming talk on the Birds of India, and one of the most charming ones is Athene brama, the Spotted Owlet: Tiny little birds (hence the diminutive "owlet"), they are nonetheless mobbed mercilessly if they don't choose their daytime hiding place carefully. At the Okhla Bird Sanctuary where I snapped the above image, they roost in a giant banyan tree at the western end of a large weir, close by a house. They're almost always there, but the trouble with finding Spotted Owlets isn't knowing where they hang out: it's spotting them! They are very good at hiding: But once spotted, Spotted Owlet is sometimes fairly confiding. A good photographer would have had no trouble getting sharper images than these. There are 4 species in the genus Athene: Spotted Owlet, A. brama, found throughout India and Pakistan; Forest Owlet, A. blewitti, a much more range-restricted Indian species; Little Owl, A. noctua, widespread throughout Eurasia and into North Africa; and one New World species, Burrowing Owl, A. cunicularia. This last species has an extremely wide distribution across both American continents, with 20 subspecies recognized by some authorities. The Burrowing Owl should have a special place in the heart of any naturalist from Boca Raton: Athene cunicularia floridana is the mascot of the local public university, Florida Atlantic University. They live on the campus, which is located on the site of a former Army Air Corps training center (part of which lives on as an airport, Boca Raton Airport). I see them almost every time I ride my bike along the El Rio Canal, which runs along the eastern edge of the campus. They like to hang out on the berms of their burrows, or on the little T-shaped perches that the campus environmental scientists put up for them. They are perch hunters, so they appreciate the boost those little Ts give them. I've lived in Boca for ten years now, and I see these little guys almost weekly, but when I searched my photo files for pictures of burrowing owls, I came up completely empty. So I set out early this morning with my digiscoping rig to rectify the situation. The owls occupy precious real estate on the campus, but for now at least, many of the most accessible sites appear to be unthreatened by development, although the new football stadium on campus is going smack on top of one of their larger sites. Just as important as their living quarters, though, and much less protected by any state regulation, are their foraging grounds. We can only hope that the university will keep enough open space for these guys to hunt the bugs and small lizards and rodents that comprise their diet, otherwise there will be no burrowing owls on campus except the wingless, featherless kind! Here are a few of the better shots from this morning's session: The yellowish cast of the photos is an effect of the light; the sun had just risen when these shots were taken. Like many birds, these owls tend to be most visible at dawn and dusk. The Burrowing Owl is the only member of its genus that lives underground. The other three species all live in trees, as "proper" owls do. The specific epithet, cunicularia, means miner in Latin, borrowed from the Greek kúniklos, which has to do with another burrowing animal, the rabbit. (Coney-cunicularia. There's a whole branch of animal husbandry called cunicularium, which has to do with raising rabbits.) And in many parts of their range, these owls do take over abandoned rabbit holes, or prairie dog holes, or whatever is handy. (The decline of the prairie dog in the Midwest has been blamed for the decline of the Burrowing Owl there as well.) Here in the loose, sandy soils of Florida, they tend to dig their own holes, although they're not too proud to take over an old gopher tortoise hole if one is available.

Frogs by the garden hose

Introduced species play conspicuous roles in any ecosystem, particularly here in south Florida, the gateway to the Caribbean and most of Latin America. Every few years we hear of the potential for ecological harm posed by the latest introduction, either those that have escaped from captivity, like the walking catfishBurmese python, or Purple Swamphen; the Everglades ecosystem is still threatened by the intentional introductions of invasive plant species like melaleuca and Brazilian Pepper. Another widespread exotic species in Florida is Osteopilus septentrionalis, the Cuban Treefrog. It's the largest treefrog in North America by far, and it's considered an invasive species here. According to the USGS fact sheet on this species,
Osteopilus septentrionalis is usually introduced through horticultural shipments and plantings (especially palm trees) (Meshaka, 1996a, b, 2001; Jackson in Meshaka, 1996a; Livo et al., 1998; Mitchell, 1999; Owen et al., 2006; Enge et al. 2008), building materials (Meshaka, 1996b; Dodd and Griffey, 2002; Owen et al., 2005, 2006), and motorized vehicles (Meshaka, 1996a; Enge et al. 2008). In addition to anthropogenic dispersal, it also is possible that they can disperse throughout much of the Caribbean by rafting on floating vegetation (Meshaka, 2001). Several authors have suggested that indigenous Cuban treefrogs may have existed on Key West and the lower Florida Keys since pre-Colombian times (Lazell, 1989; Meshaka, 2001). [All references are at the aforelinked fact sheet]
However they first got here, they certainly feel at home now. (By the way, most experts classify this frog, despite its cubacentric name, as a West Indian species, because it is widely distributed in the islands. It doesn't have to worry about the wet foot/dry foot policy...) When I came home from work yesterday, M and little e greeted me with the news that one of these alien invaders could be seen at our garden hose, and sure enough, this little guy seemed quite at home there: They don't worry about whether they're supposed to be here or not; they just go on about the business of being a treefrog. Of course, since they're larger than other treefrogs, and they are frogs, which eat just about anything they can fit in their mouths, the success of the Cuban treefrog has come at the expense of our native frogs, through outright predation and competition for food and breeding resources. Despite the fact that they are competitors of some of our dwindling populations of native treefrogs, they are still quite interesting little (and not-so-little) creatures, squawking away now and then of a wet evening, calling their call (a fairly raucous scraaaack that sounds a little bit like the call of the Southern leopard frog, except that it's usually just one note, not several short ones in a row like Rana sphenocephala), looking for love. Dorcas & Gibbons (2008) describe it thusly:
The advertisement call sounds like a rasping version of a cross between an eastern spadefoot toad's incessant qwaah and a southern leopard frog's "rubbed balloon" croak.
It's easy to tell adults of this species from just about any other treefrog on account of their size: they're almost twice as large as our native species, up to 6 inches in the largest females. It's hard to tell size from a photograph, and if you don't have a native treefrog handy to compare, or you're looking at a small individual, you need to focus on other identifying characteristics. Elliott, Gerhardt, & Davidson (2009) say that you can distinguish smaller individuals from other Florida treefrogs "by its lack of stripes and other markings running from the front of the eye to the rear and sides of the body" (120). They also note that "individuals can change color rapidly, usually from some shade of brown or tan to pale green (or vice versa), and spots may appear or disappear" (120). Another way you can tell them apart, according to my Dorcas & Gibbons, is by the size of the toepad: it's "disproportionately larger than those of any other southeastern frog" (103): Yet another way you can distinguish them from our native treefrogs is their skin: they are usually pretty lumpy bumpy, while our native treefrogs look quite a bit sleeker. Furthermore, according to my Ashton & Ashton (1988),  "There is a fold of skin from the eye over the tympanum and ending on the shoulder" (177). You can see it pretty clearly in this detail: Cuban treefrogs, at least in my experience, are also pretty blase about being approached; they seem much less shy than, for example, the still unidentified critters I saw at Lake Ida ten days ago. (This could be a sign of how successful they are as a competitor; they don't fear much, perhaps because they don't have much to fear?) This is not to say that they are entirely fearless; this individual eventually tired of all the attention s/he was getting from my camera, and decided to head for greener pastures. As it got going, though, it revealed its signature markings, the wash of color on the sides and back of the legs in this shot: We're supposed to euthanize these guys whenever we find them around, but they're so well established, and the process is such a pain, I never can find it in my heart to do that. So this guy went on his merry, and I went about my business. Cheers! If you're curious, here are the instructions from UF/IFAS on how to euthanize a frog:
To euthanize a Cuban Treefrog, hold the frog firmly in your hand and apply a 1 inch bead of benzocaine ointment along the back of the frog. Benzocaine ointment is a topical anesthetic (a numbing agent) used to treat skin pain (e.g., from sunburn) and itching as well as toothaches and sore throats. There are a variety of name brand and generic versions that are available over-the-counter in a tube or spray. If you are able to, using a gloved finger spread the ointment out on the frog's back. Alternatively, you could use a benzocaine spray. Once the ointment or spray is applied, place the frog in a plastic grocery bag or a sealable sandwich bag for 15-20 minutes so that the benzocaine has a chance to render the frog unconscious (be sure to seal the bag or tie it closed). After the bezocaine has anesthetized the frog, place the bag in a freezer overnight to ensure that the frog is dead and then throw it out in your trash. If you are unable to apply benzocaine to the frog, you can simply put it in a plastic bag, seal or tie the bag shut, then place it in the freezer overnight--dispose of the bag and the frog in the trash the next day. Do not throw a bagged frog into the trash without euthanizing it first. Remember, Cuban Treefrogs have a noxious skin secretion so be sure to wash your hands thoroughly after you handle the frog, even if you wear gloves or use a plastic bag. Freezing is a humane way to kill amphibians because their bodies go into a state of torpor (metabolism slows way down) -- just as they do in cold weather outside. If the cold weather is short in duration, the frogs will come out of their torpor state. However, after an extended time in freezing temperatures, the frogs die. A good test to determine if a frog is a Cuban treefrog is to grasp the frog firmly, but gently, and try to move the skin around on the top of the frog's head with your fingertip. The skin on the head of a Cuban treefrog is fused to the top of the skull and won't move. Be sure to wash your hands after handling any frog or toad. They all secrete a slimy film to protect their skin, but the secretions of some species, like the Cuban treefrog, can irritate the skin and eyes of some people.

Florida’s marine terraces

In an article last year about Montana de Oro state park in California, I discussed how the land there includes a series of uplifted marine terraces. Those terraces are formed by a combination of geologic uplift at periodic intervals and the eroding action of the shoreline. Well, here in Florida we're pretty conversant with the eroding action of the shoreline. But for most of the east coast, at least, the forces of erosion and deposition are pretty much balanced. What the waves take away in the winter, they deposit in the summer, or vice versa. And in parts of the coast where the underlying limestone is exposed, you can actually observe the process of lithification taking place at the same time as you see wave action eroding the rocks! A terrific example of this state of affairs can be found at Blowing Rocks Preserve, in Jupiter, Florida. It's very exciting to see the waves crashing into the rocks, scouring them and undercutting the Anastasia limestone terrace (of Pleistocene origin); it's easy to tell why this is called a high-energy coastline:

Wavesplosion at Blowing Rocks Preserve, Jupiter, Florida

Wave action undercutting terrace at Blowing Rocks Preserve, Jupiter Island, Florida.

The beach here is really something, with waves crashing into the limestone down below, while up above, the overwash creates tidepools where the sun and the salt water combine to cement the calcium carbonate shells of the marine mollusks into the cementitious rock known as coquina. The process can create some incredible combinations of erosion and formation at the same time, like this mini-arch in a tidepool on top of the limestone terrace:

Miniature arch forming/eroding at Blowing Rocks Preserve, Jupiter, Florida

Or this coquina "crater"; hard to tell whether it looks more like a volcanic or an impact crater on the moon, or perhaps the top of a fossilized sponge:

Coquina laminate formation at Blowing Rocks Preserve in Jupiter

The Anastasia formation, though, isn't one of Florida's recognized marine terraces; I'm not clear on why. Apparently, it's just a limestone formation because it's not exposed at the surface for its entire length? (See this article on raised beaches in Wikipedia, which equates the terms raised beach and marine terrace.) Basically, marine terraces form through a combination of sea- and land-level changes with the action of erosion or deposition. Marine erosion creates features like wave-cut benches, sea cliffs, and rocky headlands, all of which are on display at Montana de Oro; not so much here in South Florida. According to Anderson et al. (1999), marine terraces form when:
  • Sea-cliff retreat driven by wave erosion creates a wave cut platform.
  • The platform is abandoned when sea level drops leaving behind marine sediments covering a planar bedrock surface.
  • If tectonic uplifts rates are large enough, the old wave-cut platform has been lifted out of the surf zone by the next sea level highstand and the terrace is then preserved in the landscape.
  • Thus, a flight of marine terraces records the history of tectonic uplift and sea level fluctuation
Whatever the geologic explanation, exploring the beach is fun, and you can do it close to home, too. Further south in Palm Beach County, in my own town of Boca Raton, in fact, we can see a little bit of the formation at South Beach Park. And, if you're curious, Florida's defined marine terraces, from Randazzo & Jones, are:
  • Silver Bluff (1—3 m elevation)
  • Pamlico (2.5—7.6 m)
  • Talbot (7.6—12.8 m)
  • Penholoway (12.8—21.3 m)
  • Wicomico (21.3—30.4 m)
  • Sunderland/Okeefenokee (30.4—51.8 m)
  • Coharie (51.3—65.5 m)
  • Hazlehurst (65.5—97.5 m)
One of these days, I might even be able to take some field trips to see them! But first, I need to digest the article by Alt and Brooks linked to above; it seems to explain some of the problems of interpreting marine terraces.


The other day I was talking about spines on palm trees and got to thinking about defensive strategies of plants in general. It seems like there's a general arms race going on between primary producers (organisms that convert sunlight into energy that sustains them) and primary consumers (organisms that capture that energy by feeding on the primary producers). Since most primary producers are plants and algae, by definition most primary consumers are herbivores. So in order for a plant to pass on its genes to its descendants, it must ensure that it survives long enough to reproduce. One way to do this is to defend against being eaten. Trees are at the base of the food chain, and they are immobile, so they need to mount some form of defense. Thorns and spines often do the trick, as I mentioned earlier, but it's not just palm trees that develop them. Take, for instance, the lovely floss silk tree (Chorisia speciosa). Here's one on Dixie Highway in Boca Raton: The flowers are lovely, and the green trunk is quite striking. But take a closer look—not too close! You don't want to run into those thorns! Those thorns are quite impressive, making this lovely tree less than appealing, at least to tree-climbing mammals that might want to sample its leaves or flowers. Other organisms, though, have become so adept at adaptation that they actually benefit from the defensive strategies of some plants! For example, Florida's endangered tree snail, Liguus fasciatus, appears pretty comfortable among the thorns on that Floss silk tree! In case you missed it from the picture above, here's a cropped detail: Not many predators of snails would think to sample every thorn on that trunk just to get at that delicious molluscan meal. Mind you, I'm not saying that Florida tree snails evolved to mimic the thorns on the exotic tree native to South America; that doesn't make any sense at all. But it certainly seems like this Boca-based snail is enjoying a free ride. But as I said at the beginning, it's an arms race: as trees evolve defenses against being eaten, animals evolve ways of getting around those defenses. Some animals, like birds, bats, or insects, can simply fly right past the trunk to get to the mother lode. And that's important for many plants because those flying creatures are important pollinators (unless you're lazy, like conifers, and just release all your pollen into the wind and hope for the best—a strategy that works pretty well, as long as your population exists in big open spaces that allow the wind to disseminate your pollen long distances, and you produce enough pollen and have a large enough population to enable pollination to be successful despite all the "missed targets" that this "sème à tout vent" strategy entails). But you still need to defend against insect damage somehow. Conifers do it with thick bark, copious amounts of resin to attack anyone who gets through the bark, and large spiny pine cones to protect the seeds. Despite all this arming-up on the part of the trees, insects have a major advantage: their furious rates of reproduction. They can have scores of generations over which minor mutations can get tested in populations while one sapling grows into a young tree. These Furthermore, it's not just mollusks that use a plant's defenses for their own benefit, though. Insects have also learned to masquerade as thorns:

Umbonia crassicornis (Thorn bug)

Unlike the almost completely benign feeding of the tree snail, though, which contents itself with "cleaning" the bark of the tree of the lichens that grow on the surface, the thorn bug, Umbonia crassicornis, is a sapsucker. It feeds directly on the life juices of the host plant itself. It doesn't seem like these guys are numerous enough or voracious enough to cause major problems for the plant, though, unlike other arthropod infestations, which can defoliate and destroy trees or even whole forests (think bark beetles in the forests out west). Camouflage is an enormous topic, though, so I'll stop here and rest a bit...

How low are the clouds?

I first set foot in Florida back in 1984, on spring break from my sophomore year of high school. I was accompanying my dad on a plane trip that was to take us from our home in L.A.'s San Fernando Valley, located in a basin between the San Gabriel and the Santa Monica mountains, all the way around the perimeter of the lower 48 states: from L.A. south along the Pacific Ocean all the way to the Mexico border, hang a left and go straight along that imaginary line until we hit the Rio Grande, then follow the natural geography of the unsubmerged portion of the continental shelf all the way to Maine, I guess. (As it turns out, I never found out how easy that would have been; we were delayed by thunderstorms in Florida and snowstorms in Connecticut, and we had to hustle back across the country, putting in some truly massive marathon daylight flights.) The itinerary was an exciting idea, and like many ideas, it's the conception, rather than the execution, that holds the true thrill. There's just no way to feel in one's viscera for 8 straight very long days the intellectual thrill of flying all the way around the country in the backseat of a VariEze. But the scenery was interesting, and once we left the mountains behind, it was all pretty much new to me. I wish that digital cameras had existed back then; I'd love to have some snapshots of this trip now, if only to serve as a photo gallery for this blog... At the beginning we flew fairly high, both to increase our fuel economy and our comfort. The ground was a long way down, but if you know anything about the skies in the West, you know that the sky was higher still. The air out there is dry, desert dry. Clouds simply cannot exist close to that much aridity; it's only high, high up that what little moisture there is is able to coalesce into clouds. The view from that high up over the West, where I'd grown up, was familiar, and while I hadn't actually been in all the places we were flying over (not much call to go straddle the line between Mexico and the U.S. then, and not much call now, unless you're a newfangled minuteman, in which case I advise you to get a grip), I could easily imagine having been there, since I'd been in many places that looked almost exactly the same. El Paso was our first stop; the Franklin Mountains, which come to an abrupt halt right in the middle of the city, made quite an impression on me (image from Wikipedia):

El Paso skyline, March 25, 2009. Image by LC Rogers, from Wikipedia.

If memory serves me, the airport was on one side of the mountains, and our overnight accommodations were on the other. But it was only a short drive, because we didn't have to drive over the mountains, just around them. The stop after El Paso was Houston--that's right, Texas is so big that even in our little airplane, it took all day to circumnavigate. One day to get from California through Arizona and New Mexico and just barely squeak into Texas, and then an entire days' flying and still in Texas. Whooee! On the way to Houston we followed the curves of the Rio Grande from El Paso, over Laredo, all the way to Brownsville (what I wouldn't give to be able to do this part of the trip again, on the ground! Birding the Big Bend!), which was conveniently located both close to our flight path and just in time for lunch. Brownsville is about as far south as you can get on the mainland of the United States (Key West, which is the southernmost point on the unsubmerged land-connected United States portion of the continental shelf, is of course, not on the mainland.), and as we descended from our high flight, we rapidly noticed that we had left the dry air of the West behind somewhere: it was getting hotter and hotter, and more and humid, as we got closer to the ground. Welcome to the East! On we pressed to Houston, and then, on the third day, we crossed through Louisiana, Mississippi, Alabama, and on into Florida. We had lunch at a little town in Mississippi (Gulfport, if I remember right, but I might not: I was 14 at the time, and am rapidly approaching the palindrome of that age). From there, it was supposed to be a pretty easy flight to our next stop: Somewhere in Florida. Around here, I lose the chronology a little (Florida will do that to you). The main thing I remember about the state in 1984 was how low the ceiling was. Practically as soon as we hit the Florida border, we had to start descending, because the cloud deck was so low. There's simply so much moisture in this state, even in April, that the clouds can form really, really close to the ground. I read somewhere (can't remember where) that, although the highest point of land in Florida is only 385 feet, the state does have mountains: our towering cumulonimbus thunderstorms. Seeing them through the lens of someone like Clyde Butcher encourages this idea, and I have to say that it has some merit, but I do miss the real mountains. And I have to say that my first impression of Florida's clouds wasn't anything like an amazing tower 50,000 feet high. It was just a bunch of little gray clouds with rain coming down from most of them. Not hard, driving rain, but enough to interfere with our enjoyment of the day. I had never seen so many clouds so low to the ground, without it looking like, well, fog. This wasn't fog, though; these were individual clouds, but so many, and so close together, and above all so low, that we had to do some pretty serious fudging of the rules of visual flight to enable us to get anywhere at all. As it was, we had to make an unplanned overnight somewhere on the peninsula (Pop would remember the spot, I hope). The next day we continued on around the tip of the peninsula, spying the condos and hotels of Miami Beach from the air, and continuing our route up to Cocoa Beach, Florida. Here I got another dose of difference: while the Atlantic Ocean in Florida resembles the Pacific Ocean in California in several respects (it's large, it's salt water, it has waves), there is a palpable difference between the two. The water in Florida is warm. Coming from the cold water of the beaches swept by the California current, where the beach is only marginally fun without a wetsuit for a few months of the year (July and August, maybe September if you could get to the beach instead of school), this was a shock, although a pleasant one. So, as I freeze here in the grips of the coldest spell I can remember (last year, right around this same time, we had some pretty cold weather), it's nice to think back to the time when I first met this unruly appendage of America we call Florida. No clouds in sight today.

When is fall in South Florida?

I mean, really! The leaves of our tropical and subtropical trees aren't really deciduous, so we can't rely on the glorious fall defoliation as an indicator. This defoliation, which some people like because it's preceded by a change in color from healthy chlorophyll green to less healthy oranges, browns, and reds, is caused by hormonal changes in the tree which are in turn triggered by shortened day length and cooler weather. These hormonal changes lead the trees to sever the links between their twigs and their leaves; if you look at the leaf stem, you'll see the typical abscission marks that indicate that the autumn leaf wasn't ripped from the tree by the force of the wind; it's more like the tree was pushing the leaf off, and the wind just encouraged it to meet its fate... No, we here in Florida don't have this visual cue. What we have, as you can see in this post from the South Florida Watershed Journal (one of my favorite Florida blogs), is a temperature boundary. Robert V. Sobczak has a fabulous graphic that shows how the 60-degree line advances slowly across the state from north to south. By this definition, fall won't hit Boca for a few weeks! We did get an early precursor of its arrival in the middle of October, but we certainly didn't get the "typical" fall arrival that I predicted (because, you see, I based my prediction on my memory rather than the data). I always tell people that I never thought I'd wind up in Florida, but now that I'm here, I don't want to be anywhere else between Halloween and Easter. Well, make that Thanksgiving and Easter, now! Fall starts late down here! This week the weather has begun to moderate somewhat; we're finally coming down from the record heat (daytime highs from the high 80s to low 90s in November!) to "normal" temperatures, but, as that graphic shows, we have a ways to go before we feel the full blast of fall. Brrr. 60s!
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