Stories of the Swamp

Armchair Interpretive Walks

Friends of Fakahatchee: Dedicated to financial and volunteer support to preserve the unique ecology and cultural heritage of Fakahatchee Strand Preserve State Park and educate the public about its importance.

Night Ramblings

Night Ramblings
by Patrick Higgins

 View of South Oxfordshire from atop the Chilterns at Watlington Hill. Photo by Patrick Higgins

View of South Oxfordshire from atop the Chilterns at Watlington Hill. Photo by Patrick Higgins

Late July found me stumbling down a sunken way with Martha in the pitch dark of a moonless night. Our rough path was hemmed in by ancient yew and beech trees. We were in the Chiltern Hills of South Oxfordshire – an area designated as being of Outstanding Natural Beauty, a Site of Special Scientific Interest and a Special Area of Conservation about 15 minutes from our son’s house in Watlington where we were staying.  The broad bottomed ditch we were negotiating dated back to Saxon times.  In the darkness with the clinking of key chains and water bottles one could almost hear “the tramp of Saxon foemen, Saxon spearmen, Saxon bowmen” although more commonly this path would have been trampled by generations of Saxon farmers taking their animals to market; merchants with their wares travelling between settlements and woodsmen hauling timber and charcoal.

Further down, the sunken way was bisected by an old Roman road, now resurfaced and travelled by cars. For some unknown reason the Roman routes are always straighter than most of our modern English highways. Behind me, back up the hill, our ditch led to the Ridgeway, Britain’s oldest byway dating back over 5,000 years, which stretched from the Norfolk coast to that of Dorset, linking up Neolithic sites like Stonehenge and Avebury.  It’s hard to escape history in England, but we were in search of the glow worm (Lampyris noctiluca), cousins to Fakahatchee’s fireflies in Aston Rowant National Nature Reserve.  However, in the dark my mind kept wandering to the Fakahatchee because I had to give a talk locally on the Everglades Ecosystem and was also planning some new night-time interpretive programs for the upcoming season back in Florida.

The Reserve is a mosaic of chalk grassland, beech woodland and Juniper scrub sitting atop 300 feet of chalk, formed 350 million years ago from the compressed calcite shells of microscopic Foraminifera that lived in the warm, shallow seas that once covered southern Britain.  Chalk grassland is a unique and fragile habitat, important for both its beauty and wildlife value. It is the product of centuries of grazing by animals on nutrient poor chalk soils and is characterized by a short turf rich in herbs, flowers, butterflies and grasses, and like the Fakahatchee also in orchids, although here they are all terrestrial.

Comparisons between the ecosystems continued to flood my thoughts as we bumped along. In one we employ prescribed burns to maintain the habitat. Here, it’s the grazing of a large flock of speckle-faced sheep and a few Dartmoor ponies that controls the spread of young scrub and keeps chalk grassland healthy.

Aston Rowant, at only some the 500 acres, is a classic example of the threat to biodiversity through islandization and habitat fragmentation. Especially as even this small, precious parcel is sliced into two by a massive cut for the six lane M40 motorway from London to Oxford which paralleled our route just over the rise. It was further affirmation why the Fakahatchee is important; not just because of its unique plant communities, but also as Florida’s largest State Park because of its scale. When it comes to maintaining biodiversity, size does matter!

Back in Florida swallow-tailed kites would just be beginning to assemble for their annual 4,500 mile return migration to South America. Here there were Red kites (Milvus milvus).  They had been reduced to just a handful of pairs in Wales through past persecution. It was mistakenly believed that they were a threat to gamebirds and livestock, but recently they have made a remarkable comeback. Through a reintroduction program using chicks taken from northern Spain there are now some 250 breeding pairs in the Chilterns.   With a 5 ½ foot wingspan Red kites are a much larger bird than our swallow-tail, weighing 2 – 3 pounds versus 10–20 ounces and their ecological role is different too. Rather than being canopy feeders they are primarily carrion feeders, filling the role of vultures, although they will take small mammals too if caught in the open. The locals who once persecuted them now throw the bones from their Sunday joints out on to the lawn to watch them swoop in, a practice sadly that does not encourage the kites’ dispersal into new territory.

Field of yellow meadow ant mounds. Photo by Phil Champion

Field of yellow meadow ant mounds. Photo by Phil Champion

In Florida the instant we step off the road we are on the alert for fire ant nests.  Here there is an unseen benevolent ant, the Yellow meadow ant (Lasius flavus). The chalk grassland and other undisturbed ancient pasture areas are dotted with myriads of small grassy domes that look almost like neatly planted helmets. These are actually ant-hills, some over a hundred years old. Inside of each is a colony of up to 5,000 meadow ants that feed the by farming the sap sucking aphids that live on the roots of the surrounding forbs and grasses.  The ants milk the greenfly for honeydew which they carry back to their colony and in the winter will eat the aphids themselves. Their subterranean activities control damaging insects, open up the soil keeping it porous and their droppings fertilize the grasses’ roots. They also have a curious relationship with the Chalkhill blue butterfly (Polyommatus coridon). Attracted by secretions they will bury the pupa, unintentionally protecting it from predators.

Wingless female glow worm (Lampyris noctiluca). Photo by Barry Crowley

Wingless female glow worm (Lampyris noctiluca). Photo by Barry Crowley

After about 45 minutes bumbling about we finally detected the steady green glow of our target, a glow worm.  It was about a foot off the track, naturally in completely the wrong spot deep in the woodland.  Glow worms of course are not a worms at all but a bioluminescent beetle just like our related firefly.  In their larval stage they are predatory and hunt snails, which why calciferous habitats that favour snails like chalk grasslands are preferred. As adults they rarely feed.
In the glow worm’s case it is only the inch long wingless female that glows significantly.  She had climbed up a dried grass stem about 12 inches above the ground then curled her abdomen slightly upward to display the last few segments of her abdomen where her glowing organs are located in hope of attracting a passing male.  Unlike American fireflies she can’t readily turn her glow on and off – it’s rather like a very slow starting fluorescent tube, which takes about 20 minutes to cycle so they don’t flash.  Misplaced deep in the woods she would be very lucky to have any success.  As well as attracting a mate, the glowing abdomen is a warning to predators to stay away – bioluminescent chemicals taste bad.

Nevertheless, hers is a very efficient light source. Unlike incandescent light bulbs that only, transform about 3% of the energy used into light, bioluminescence is generally 90 to 98% efficient.  The light is produced by a reaction between calcium, luciferin and ATP in the presence of the catalyst luciferase and oxygen, using nitric oxide as a chemical on/off oxygen valve. It is the switching on and off of the oxygen flow which allows American fireflies to flash.  Specific flash patterns are used to identify other members of their species, as well as members of the opposite sex and even. In the case of some Photuris fireflies, it is to mimic the light signals of other firefly species to lure, kill, and eat them.  Studies of America’s most common Photinus species show that females are more attracted to males that flash longer and faster. A flash can bring either sex or death!  We shall be trying a bit of mimicry ourselves on our moonlight tram rides down Jane’s Scenic Drive this season to see if we can attract any eager males.  It’s just a case of getting the response timing right.

Anyways, that solitary glow worm by the trail was the only one we saw that night.  We scoured the open grassland to no avail.  I guess we missed the peak by about a week, but even then observers were only seeing a dozen specimens a night on this site. Light pollution as well as habitat loss is taking a toll on these interesting insects.  We’re pretty lucky in the Fakahatchee.

What is a Snag?

by Sam Peters

snagbypetermcclure4webThere is some debate about what constitutes a Snag, Is it a dead tree? Is it on the ground? Is it in the water? Is it a loose thread? The Urban Dictionary defines snags as a “sensitive new age guy.” So, there are many definitions … For our purposes, a Snag is a standing dead or dying tree.

A Downed Tree is a log lying on or near a forest floor; however, a downed tree in a body of water is called a snag in certain areas of the South and Midwest. In Alaskan rivers it can be called a preacher. Other areas it is called a sawyer. Both sawyer and preacher derive from the tree or log rising and falling and bowing in a current of a river.

To some people, Snags are ugly and should be removed from a forest. After all, they are not classic, formal beauty; they’re dead. However, trees are the gift that keeps on giving. As they grow, they provide habitat and shelter for many different species; when they die, they still provide shelter and habitat, but now for different animals. Depending on the species of tree, it can last for as long as 70 years. They start out as Hard Snags, which means that they still have the bark and their cambium layer; as they lose their bark and decay further, they become Soft Snags. This is when the most animals begin to move in.

Some of the birds which use Snags are woodpeckers, wrens, barred owl, vultures and hawks. Also many insects, reptiles and amphibians call a dead tree home.

As the tree ages, different animals make use of it. For instance, woodpeckers will make use of an area of a snag and when the woodpeckers move on, other birds will enlarge the holes and move in. As they move on, more birds or other animals will make use of the cavity. This can go on until the cavity becomes large enough to house a squirrel, or a raccoon nest.

Some fungi, moss, and lichen live their entire lives on dead trees. Bacteria live in decaying wood, creating fertilizer which will mix with the soil when the tree falls. Shelf mushrooms make use of Snags and Downed Trees. Snags provide food and habitat for almost 1/3 of our wildlife. Over forty different types of birds use Snags at one time or another.

Snags should be protected and left standing for reasons of habitat and forest health. They are used for foraging, nesting, perching, hunting and roosting.

We need Snags to be maintained in a variety of sizes, shapes and ages. A group of larger Snags is more valuable as it provides habitat for a greater variety of species. Small clumps of snags will provide nesting and foraging sites. Snags should exist in various stages of decay, as they support different plants and animals at different stages of their existence. So, different stages for diverse species and different sizes and shapes for the same reason.

A single large Snag is rarely used by more than one pair of the same species.

Forest management now includes Snags. This would include not cutting down dead trees and culling trees in a crowded area, but leaving them standing and creating new Snags. Fire may also be used as fire can both create new Snags and destroy old ones.

What can we do? Depending on where we live, we can maintain Snags and/or create new ones. Please don’t use fire in your neighborhood. However, if a tree dies, leave it alone if it is not a danger to anything or cut it to a size where it will not hurt anything if it falls. You may also kill an unwanted tree yet leave it standing. Some of the ways to kill it would be to gird the tree, top and trim it and of course poison always works. Girding does weaken the tree and if done will rot the tree from the outside in. This will cause the tree to rot and fall much more quickly than when it dies and rots from the inside out, which is the natural way.

The Fakahatchee has many Snags in various states of decay. They occur naturally and are of great service to the forest community. If you look closely, you can see that the Snag is occupied by many animals and if you look twice you may even come to believe that they are beautiful in their own natural way.

Sam Peters is an FOF member from Miami Beach.

The Wetland Neighbors

by Anthony (Tony) Marx

Aerial  photo   of  the  “south blocks”  in the  Picayune by Marya Repko taken several years ago.

Aerial photo of the “south blocks” in the Picayune by Marya Repko taken several years ago.

Once considered as useless and a noxious, snake and insect infested source of fevers which must be drained and developed, half of the wetlands that existed at Florida Statehood have been destroyed. However Collier County is blessed with over 72% of its land acreage designated as conservation land – more than twice that of neighboring counties.

There is a stark difference between the 85,000-acre Fakahatchee State Preserve and the adjoining Picayune State Forest, which at 78,000 acres is almost as large. The Fakahatchee is a vibrant, natural world pulsating with life and home to a huge variety of rare plant life and endangered animals; whereas the Picayune, once also a similar wetland, was logged, cleared and partially developed, then abandoned. This transformed it into a dry landscape with upland trees and vegetation. Non-native vegetation including Brazilian Pepper, always present when land is disturbed, also moved in. Over two hundred miles of elevated roads acted as levies to further stop natural water flow between the canals. The difference is most noticeable when you access the Picayune State Forest through its back entrance at the end of Janes Scenic Drive in the Fakahatchee State Park. Outdated maps show a grid of streets which are mostly non-existent. The massive Comprehensive Everglades Restoration Plan (CERP) is changing the landscape in every respect. The bridge, on entering over the former Prairie has gone and the canal plugged, so it is now a series of small ponds.

Photo of equipment filling in a canal by Dennis Giardina.

Photo of equipment filling in a canal by Dennis Giardina.

Heading west, the partial dirt and paved road still shown on maps as Stewart has been leveled flat with the surrounding landscape, and on either side large swathes of scrub have been bulldozed clear of all vegetation and leveled to start sheet water flowing. Progress is occasionally blocked at the next canal bridge, but if you can proceed you’ll find that the formerly paved Everglades Boulevard section leading to Naples has also had its surface removed and the last time I was there it was gated closed. Heavy equipment is seen working here and there, bulldozing and trucking away debris. Close to I-75 instead of water flowing south down canals to the estuaries, the new and powerful pumping stations under construction will send water flowing fanlike south through spreader channels in an east-west direction while the remaining three canals running north to south will be plugged to varying degrees.

Boulevard in the Picayune taken by Tony Marx in 2011.

Boulevard in the Picayune taken by Tony Marx in 2011.

If you plan to try and reach Naples from the Picayune be prepared to turn back, as the road may be blocked by either a closed gate or sheet water in summer. In time it will return to a wetland environment and the interior will be mostly be inaccessible to vehicles. The full transformation will take several decades but soon the Fakahatchee will benefit from the additional water flowing southeast.

Tony Marx is a Florida Master Naturalist and a Board Member of Friends of Fakahatchee. He was one of the speakers at our Annual Dinner on April 13.

Messengers from Above – The Swallow-tailed Kite

Swallow-tailed-Kite-for-webby Patrick Higgins

I start looking on Valentine’s Day and saw my first swallow-tailed kite of the season on March 1st. sailing just above a hammock in the southern reaches of the Park.   It seemed almost paper thin, flashing white then black as it effortlessly swooped, turned and soared, changing direction in an instant with slight adjustments of its scissor-like tail.  Native Americans saw these birds as the Great Creator’s window on our world or as messengers between the world above and ours below. For me too they have a spiritual quality and never fail to bring joy.

My excitement was heightened by the knowledge that this herald of spring had journeyed over 4,500 miles from the Pantanal, a vast Everglades-like wetland straddling the borders of Brazil, Bolivia and Paraguay, to nest here and then would repeat the trip home in September.

Males and females are indistinguishable in size and plumage.  My kite would already have formed a breeding pair during migration and then together sought out a nest site in a tall tree.  In the Fakahatchee swallow-tails favor the very top of slash pines on Four Stakes Prairie.  They usually nest in clusters within a few hundred yards of a couple of other pairs laying 2 – 3 white and brown splotched eggs, which need three weeks incubation. From hatching to fledging takes another 6 weeks, although only one usually survives to this stage – the others having been killed, out-competed for food or pushed out of the nest by the first chick to hatch.

In flight Swallow-tailed kites appear petite and delicate as they perform their aerial ballet, but their wing span is over four feet. They seldom flap their wings, making flight look completely effortless.  They seize prey like dragonflies and wasps midair and deftly pluck tree-frogs, anoles, small snakes, cicadas and baby birds from the forest canopy.  Unlike other raptors they eat on the wing as they continue searching for their next meal, and even drink and bathe on the wing, skimming the surface of ponds and rivers.  They mainly feed vertebrates to their young, but most of the adult’s diet consists of insects.  Due to their aerial prowess swallow-tails have few natural enemies, but are vulnerable to nocturnal predation by great horned owls.

Sadly their distribution in the United States has been steadily reduced by direct persecution in former times and continuing changes in land use and habitat loss.  They now occupy less than 5% percent of their historic range with only a few thousand individuals found in the southeast, Florida and parts of Texas, making each sighting seem even more miraculous.

A White Tie Affair

A mass of wading birds feeding on concentrated prey during the dry-down on the salt marsh south of the Trail. Photo by Patrick Higgins

A mass of wading birds feeding on concentrated prey during the dry-down on the salt marsh south of the Trail. Photo by Patrick Higgins

by Patrick Higgins

Last month I was tearing along Tamiami Trail for an early morning FOF meeting when my eye was caught by one of those Florida spectacles that just stop you in your tracks.  Late or not, I squealed over onto the verge.  Hundreds upon hundreds of birds were engaged in a feeding frenzy in a series of ephemeral ponds stretching southward across the tidal marsh, just north of the East River. Crowds of great egrets, snowy egrets, white ibis, wood storks, cattle egrets and even white pelicans were hobnobbing in the pools.

As they strutted and bobbed they were perfectly reflected in the waters below. There was a constant fluttering of wings and an undercurrent of coarse “arrr, arrr, arrrs” from great egrets, and what sounded almost like a heron being throttled, followed by a hyena-like cackle from the snowys.  Scattered amongst this host were a few great blues, and a few spoonbills, but it was very much a white tie affair. They were gorging themselves almost shoulder to shoulder on the highly concentrated prey resulting from the seasonal dry-down. By my return in the late afternoon the birds had all dispersed.

But 80 years ago a Russian ecologist named Gause developed the Competitive Exclusion Principle. He postulated that two or more species, having identical patterns of resource use can not coexist in a stable environment, as one will be better adapted and eventually out-compete and eliminate the other.  So how do all these different species coexist?

This free-for-all is the exception.  The superabundance had allowed each species to temporarily step out of their niche.  Most of the year direct competition is avoided by resource partitioning. Although the birds share the same habitat, they avoid direct completion by either exploiting different resources, or the same ones but in different ways. This is largely achieved by specialized bill adaptations, varying leg lengths, and differing hunting and feeding strategies.

The ibis (Eudocimus albus) for example feeds by probing with its narrow decurved bill in a frenetic manner. It explores in, around and under obstacles. As a result it captures a higher percentage of invertebrates, typically crayfish and insect larvae in fresh water, and small crabs in salt water. Much of the ibis’ quarry is taken directly from burrows or other hiding places, and this strategy seems equally adapted to our lawns.

The wood stork (Mycteria americana ) typically feeds in water 18” or less with its head down. It’s a grope feeder – swinging its partially open beak from side to side until contact is made. This triggers one of fastest reflexes in the animal world. Its bill snaps shut in 3/100th of a second.  Sometimes the wood stork also sloshes its feet about to startle prey. Its tactile feeding technique works well in turbid water, but prey must be abundant to be effective and it’s ineffective in clear water as potential prey can see and evade them. Hence their nesting time coincides with the dry-down when prey is concentrated.

The roseate spoonbill (Ajaja ajaja), has an unusual spatulate-shaped bill which it swings from side to side, open-billed and submerged to stir up food as it wades in shallow water.  Like the wood stork when it feels a prey item it snaps its bill closed, pulls the prey out of the water, and swallows it.  Several birds often team-up forming a cooperative line. Most of their feeding is in salt water areas and their food is primarily crustaceans- especially prawns and shrimp, which aids the development of their pink coloring.

The great blue heron (Ardea herodias ) on the other hand by virtue of their large size – up to 4’6”, are able to fish in waters deeper than other wading birds. They are fairly representative of the 12 Florida species in the heron family. They are all visual hunters and mostly tallish birds that tend to stand upright and still in shallow waters or on the shore as “sit and wait predators” staring intently at the water, or patiently stalking through them. When prey is spotted they dart out their long necks to seize or spear it. Great blues tend to be solitary hunters not tolerating the close presence of other birds and are able to tackle larger fish up to 15” or even small mammals.  Some of the other herons may employ lures like the snowy wiggling its yellow feet to attract prey, or the tricolor heron may dash about in a shallow pool, then suddenly stand stock still with its wings out to create shadow to attract the panicked fish.

Resource partitioning may be temporal as well as spatial.  We have two nocturnal specialists, the black-crowned (Nycticorax nycticorax) and yellow crowned night heron (Nyctanassa violacea), although the former is the more nocturnal. Both of these stocky birds have larger eyes to aid night vision, but comparatively short legs for herons.  This restricts them to shallower water. They prefer wading on mud flats and sport heavy shear-like bills to tackle their favourite prey: crabs and crayfish, which they pull apart before ingesting.  Unlike most herons they prefer not to stand in the water when hunting, but to perch on mangrove roots or other objects at the water’s edge, leaning over to seize their prey.

Other wading birds like the limpkin (Aramus guarauna) are even more specialized with a chisel–like bill to tackle their favourite food, the Apple snail. After breaking through operculum,  the snail’s trap door, it slips its lower mandible into the shell to snip the muscle that attaches the snail to its shell and extracts and swallows it whole.  Its lower mandible actually curves slightly to right to accommodate curvature of shell. Although it hunts visually the limpkin can also probe tactilely under surface vegetation and in turbid water. Due to its selective diet it encounters little competition from other wading birds.

Similarly the cattle egret has carved its own niche via its association with cattle and by frequently hunting in terrestrial habitats.  Similarly differences in heron sizes sort them into what depths they can stalk. While diminutive green-backed herons are restricted to hunting on the edge and extreme shallows, great blues can wade out into substantial depths and tackle sizable fish that would be impossible for a greenback to handle.

So while the great blues, greenbacks and snowy egrets pursue fish, white ibis forage for fiddler crabs, roseate spoonbills sift in search of tiny aquatic invertebrates and least bitterns snap at dragonflies, all avoiding direct completion through resource partitioning aided by their specialized bill and other adaptations.

A Window On The Strand

by Patrick Higgins

A-window-in-the-strand-for-webAbout 1 ¾ miles up Jane’s Scenic Drive just after the first bend there is a distinct ecotone where the prairie on either side abruptly transitions to forest. You’ve entered Fakahatchee’s strand; the world’s largest subtropical strand swamp and a geological feature unique to southwest Florida that provides habitat for many threatened or endangered species.   Technically a strand is simply a shallow, water-filled channel in which trees are growing. But it’s more than that. The Strand’s canopy moderates extremes, creating a microclimate that retains humidity, making it just a little bit cooler in the summer and a little bit warmer in the winter. This in turn allows a rich community of native bromeliads, ferns and orchids to flourish; it literally drips with life.

180 yards beyond the entry into the Strand, where a culvert passes under the Drive, there’s a small semicircular pond on the right that provides a window into this world. It’s worth pulling over to dwell a while, but best to go on some 20 yards and then double back on foot so you can approach slowly and quietly.

A broad slough spills out of the swamp here before it is channelled under the road.  On this windless early January day mottled grey pop ash trunks and a blue sky were perfectly reflected in the pool below.  Despite the Sun’s glare I could see a school of sailfin mollies (Poecilia latipinna) close by, hanging almost motionless in the 2 foot deep, tea-colored water. This robust native fish is the same that is often chosen for home aquariums, probably because they can tolerate a wide spectrum of conditions from low oxygen to high salinity. Their natural range is a crescent from North Carolina around through Texas to Mexico’s Yucatan, including Florida. Sadly someone thought it would be a good idea to introduce them to California’s hypersaline inland Salton Sea. A perfectly benign species here is now out-competing the endangered desert pupfish (Cyprinodon macularius) there. We can’t leave well enough alone.

Beyond the mollies but still beneath the surface are feathery patches of bladderwort (Utricularia inflata). The whole plant is submerged with only their yellow buttercup-like flowers poking above the surface. Their flimsy roots do little more than serve as anchors.  The plants absorb what nutrients they can directly from the water through their thin cell walls. But the slough’s acidic waters are nutrient poor.

Like some other bog and swamp plants, the bladderwort has evolved a means to supplement this pathway by exploiting the ready availability of essential biochemicals in animal tissue. It is carnivorous. Some of its leaves are modified into bladder-shaped traps to ensnare passing zooplankton and even small fish hatchlings. These operate like the compressed bulb of an eye-dropper. Minute hairs around the bladder’s mouth are touch sensitive. When stimulated they cause the bladder’s walls to relax, sucking in passing prey that is then slowly digested.

At the back of the pool is a rhizomatous mass of emergent vegetation between a wall of heavily buttressed pop ash trunks.  Their buttresses probably serve a similar function to those of cypress trees, helping to absorb oxygen. Today this part of the Strand is a pop ash swamp, but it wasn’t always so. These trees would have been an understorey species before the cypress was logged. Even though logging ended almost 60 years ago the damming affect of the road and the culvert’s channelization has probably kept the water high enough at this particular spot to prevent cypress seedlings from establishing. It’s very hard to undo man’s work.

Something caught my eye at the back of the pond; an almost imperceptible out-of-place shape. The principles of camouflage and concealment from my army days (shape, shine, shadow, sound, movement and color) came seeping back into my mind as I peered harder. Yes!  I could just make out an alligator’s eye ridge barely above the surface. Nearby a darker crouched shape attracted my attention. It was a little green heron obscured behind a tangle of leaves. It slowly emerged, picking its way towards the hidden gator. I suspected that they were both aware of each because it foraged just so close, then changed direction. And when it did so, the gator, now discovered, moved out a little into the open pond to expose and orientate the bony scutes along its back to the Sun and warm up. If dinner was out of reach, there was no point in being cold.

But most notable was that midway up the pop ash trunks, amongst the narrower-leafed cardinal airplants (Tillandsia fasciculata), a scattering of giant airplants (Tillandsia utriculata) still hung on. These bromeliads are ecosystems in themselves.  Their aerial ponds support a microcosm of life.

Sadly these giant tank epiphytes are an increasingly rare sight due to the depredations of the Mexican bromeliad weevil (Metamasius callizona) – an invasive exotic.  This so-called evil weevil arrived in Florida from Mexico on imported ornamentals. The giant airplant is particularly susceptible because of its ‘big bang’ reproductive strategy.

All our other native bromeliads reproduce both asexually (typically by pupping) and sexually. The giant doesn’t propagate vegetatively at all, and only flowers once in its 10-20 year life span, after which it dies. That’s a long time to be susceptible to the weevil with plenty of opportunity for infestation before reproducing. If it does successfully reach this stage, the giant airplant pushes up a huge flowering shoot over 6 ½ feet high in a final burst of energy. This may ultimately bear 10,000 seeds which are then dispersed on tiny wind-borne parachutes.

Several stages of the weevil’s life cycle may be busy eating away various parts of the plant at the same time, but the death blow is when their larvae bore into and shred the plant’s stem tissue to build cocoons. The answer may be biological control. A lot of work has been done on an imported parasitoid tachinid fly, Lixadmontia franki. After extensive testing these have been released in small numbers but rearing them in sufficient quantities has been problematic. You have to have bromeliad weevils for them to prey on and these then need bromeliads to feed on. They’ve tried using trays of pineapple tops leftover from supermarkets for the latter, but the process isn’t completely cracked yet.

The weevil’s devastation has been progressing inexorably southward through the Fakahatchee. But I’m an optimist and like to believe that perhaps the solution lies here in the bromeliad’s gene pool by our little pond. Maybe the random genetic shuffle of sexual reproduction has produced a combination that is somehow resistant in this location. We’ll have to keep observing.

Another possible salvation might be giant airplants surviving in isolated hammocks or cypress domes. The weevil is a weak flyer that travels from branch to branch rather than over long distances and perhaps these reservoirs may serve to repopulate the Fakahatchee in the future.

My thoughts returned to the scene before me and my eyes moved upward to the grass-like tufts of reddish-tinged southern needleleaf (Tillandsia setacea) higherin the trees. Behind them I could just make out the white blotches of several roosting egrets. As I lingered I heard the plop of a fish, then the mutterings of some herons and finally the flap of wings. I turned to leave. On the other side of the road, a limpkin was patiently stalking over some logs floating in our slough which continued ever so slowly to carry the Strand’s waters towards the sea. All this in a fifteen minute stop – that’s the Fakahatchee!

Under the Dome

by Patrick Higgins

Photo by Rose Flynn

Photo by Rose Flynn

For a change of scene I decided to visit a cypress dome instead of a prairie hammock. The mid-December day I choose coincided with the passage of a rapidly moving cold-front, so I set off under a grey sky. I had noticed a classic dome on Copeland Prairie on a previous excursion and thought it would be fun to investigate, as domes are really the opposites of tree islands, as I shall later explain. My target was located 1• miles up the track running north from the first bend of Jane’s Scenic Drive.

I had expected the Prairie to be essentially dry like Lee-Cypress across the road, so was lazily sporting calf-high Wellington boots appropriate for muddy English country walks, but which would fill with water if overtopped. As it turned out several inches of water remained, perhaps because of JSD’s damming effect. I found that I had to teeter-totter along the track’s central ridge to avoid sections where the ruts were perilously deep – something I wouldn’t have thought twice about if I was wearing my regular ‘wet’ boots. But this gave me the opportunity to observe the little mosquito fish that had been concentrated in them and only weeks before were spread all across the Prairie.

Photo by Patrick Higgins

Photo by Patrick Higgins

Dull light isn’t the best to appreciate the Florida landscape, but to either side, bare hat-rack cypress stood like lonely sentinels. These dwarfs, standing only 10-15 feet high, are stunted pond cypress that eke out a meagre existence on slivers of soil over the prairie’s bedrock and may actually be over 150 years old, deserving our respect. There’s debate whether pond cypress are a separate species from bald cypress (Taxodium distichum) or merely a variety of the same species (var. nutans) but opinion seems to be leaning towards the latter. Whatever the taxonomy, pond cypress do have special adaptations to the harsher niches they occupy, including thicker bark to increase fire resistance and needles closely appressed to their upturned branchlets to aid in water retention, versus the droopy feathery branchlets of bald cypress.

All around me the almost fluorescent, blue, bobbing heads of Glades Lobelia visually popped against the dry grass along with the intense white of String Lilies in their prime. There were still the occasional Grassy Arrowhead in bloom, but these had long peaked and were looking forlorn. Crushed Water Hyssops underfoot released a minty-lemon fragrance and attracted White Peacock butterflies. Frosty-colored Liatris seed heads released tufts of white as I brushed by, and the odd apple snail shell caught my attention. With the sound of the wind as a companion, I had a delightful hour’s hike to the dome. A line of Slash Pines, perhaps only inches higher in elevation gradually closed in from the west at my destination leaving only a narrow gap for the track to continue onwards.

As if on cue a ray of sunshine pierced the clouds transforming the grey leafless dome momentarily to gold. With the Sun appeared several Halloween Pennant dragonflies and a Scarlet Skimmer. I stopped to take a photograph and despite the shallow depth of the mud, my boots began to stick, pulling out with a distinct pop as I left the track to approach the dome. My cypress stand was some 80 yards in diameter. Classically lower trees encircled it and each succeeding concentric ring rose slightly higher creating a perfect dome shape with the tallest trees towards the center perhaps as high 70 feet and certainly besting the tallest pines nearby.

To the uninitiated cypress domes are counter intuitive. They appear from a distance almost as little hillocks but are in fact water-filled depressions, at least in the wet season, which brings us back to opposites and prairie hammocks. Those tree islands typically develop on limestone outcrops that raise them slightly above the surrounding terrain. Cypress domes, however, form in slight depressions created when weaker areas of limestone bedrock subside or dissolve from the action of the acidic by-products of rotting plant material. One might think the taller trees in the middle represent greater age, but the difference in height may be down to increased growth vigor instead.

Photo by Rose Flynn

Photo by Rose Flynn

Imagine a newly formed depression on the prairie. The initial trees that colonize the beginnings of that ephemeral pond will have no better soil conditions than our hat-rack cypress. So an outer ring of stunted trees develops. Over time they drop their needles into the pond creating slightly better soil conditions for the next ring of trees which grow slightly taller, and so on and so on. Each successive ring also has a slightly longer hydroperiod because they are further into the bowl. So the tallest trees may not necessarily be the oldest trees, rather they have just experienced the best growing conditions. And to confound the model, were we able to count the tree rings of outer individuals, they might not be older because the outer trees also experience the highest mortality due to a shorter hydroperiod and greater susceptibility to fire.

Cypress trees, like all aquatic organisms, face certain challenges from being periodically inundated. Water is an excellent solvent, able to readily transport most chemicals required for life, but it’s also about 10,000 times more viscous than air, meaning that life supporting gases, primarily oxygen and carbon dioxide move very slowly in their dissolved state, requiring special adaptations. Water lilies for example have hollow stalks so that oxygen can be channelled to roots buried in anaerobic muck. On the outer fringes and into the dome’s interior I encountered cypress knees; those knobby conical structures that have proved such a mystery to scientists.

All sorts of sophisticated experiments have been conducted over the past 80 years, even hermetically sealing them in transparent cases with hoses connected to all sorts of instruments, but the results are inconclusive or contradictory. However, most likely they are involved in some sort of gas exchange as they typically grow to an average height just above the local site’s mean high water level, and they also provide some sort of anchoring mechanism as they typically appear where the root system takes a distinct downward turn, perhaps here in South Florida exploiting a small solution hole. We also know they store starch.

Although the dome was dominated by cypress there was a struggling understorey kept in check by the cypress canopy’s shade. It comprised pond apple, Dahoon holly, pop ash, a few Carolina willow and some cabbage palms near the outside; all species that create a succession canopy in swamps if there is a perturbance like logging or fire. This one sheltered some sparse sawgrass too.

The cypress trunks had characteristic buttressed bases. These swellings help them absorb oxygen and provide stability in high winds. I could detect the normal high water level from the line where the patches of lichens ended. The closely spaced trunks serve to dampen air movement and trap moisture under the canopy, so that higher up, the cypress branches were festooned with bromeliads.

Cypress cones. Photo by Rose Flynn

Cypress cones. Photo by Rose Flynn

Waxy cones and pendulous catkins hung on many of the cypress and the typically clear water below was instead dusted with their pollen. Each cone typically contains 16 seeds that look a bit like dried-up petals the size of a finger nail. Squirrels often messily tear apart ripe cones and in the process drop seeds. In the not so distant past noisy flocks of now extinct Carolina Parakeets would have also performed this service. The seeds then need a complex sequence of conditions to successfully germinate. Ideally they will fall into water where they can soak for several months to soften their tough outer husks, but they can’t germinate there and must ultimately settle on exposed, but moist soil. This is why cypress trees need alternating wet and dry.

The seedling then must quickly thrust upwards to avoid being submerged when the rainy season returns or they’ll drown. Once mature however, they can survive both periodic flooding and drought. Because of this, if there’s permanent water in the center of the dome, there will be what looks like a donut hole from the air, devoid of cypress.

My dome was true to form and sure enough as I sloshed inward I encountered a small flag pond open to the sky. The alligator flag indicated even deeper water. Had I been a truly dedicated scientist I would have waded into the center to measure the depth, but in the dry season these frequently become gator holes, and as I was alone and had the excuse of inappropriate boots, I opted just to admire the pond then head home. My hike back was much quicker as I decided to bypass the rutted track altogether and found it much faster striding over the firm prairie in just a few inches of water. It helps to have long legs though!

Beneath the Prairie

By Patrick Higgins
patrick-higgins-for-webI happened to step out on the south end of Lee-Cypress Prairie on the very day in mid-October when the last of the water receded. That event was so fresh the black mud was still glistening. As I stood still to take in the scene I could hear water seeping back into my footprints. The grassy arrowhead, whose white billowing flowers had dominated the prairie only weeks before had now mostly gone to seed.

prairie-rose-flynnThis year’s rain had come early and heavily, and as the whole Prairie tilts ever so slightly to the southwest, water had stood here long and deep enough that most of the clumps of bunch grass had rotted away. This left wide spaces between each arrowhead plant. On the surface between them was a patchwork of overlapping prints from half a dozen species of wading birds that had feasted here only days before on their concentrated prey of amphibians, small fish and crustaceans. They had now moved on.

But something else was happening. All around me the surviving crayfish were busy excavating their burrows down to the water table where they would spend most of the dry season. Their chimneys looked like piles of miniature black meatballs and their earthworks contrasted starkly in patches where the dun-colored periphyton had already dried.

photo by Patrick Higgins

photo by Patrick Higgins

At 3 to 5 inches, crayfish are the Park’s largest invertebrates. There are something like 350 species in North America. Some are obligate burrowers and others not, and many of them are such habitat specialists that they may occupy only one particular river basin system. We have more than 50 species here in Florida, even some cave dwelling troglodytes, and two that make the Fakahatchee their home. These are the similar looking Everglades Crayfish (Procambarus alleni) that we find on the wet prairies and the Slough Crayfish (P. fallax) who are less adapted to seasonal drying and favor more permanent water like their namesake sloughs.

Crayfish are non-selective omnivores. They will eat almost anything organic they can catch or scavenge and chop up small enough to put in their mouths, including algae, plant material, fish eggs, worms and insects. But they’re also cannibals too, usually directed from larger to smaller and particularly molting individuals. Like all arthropods they have a rigid exoskeleton and need to periodically molt to grow, and it is at this stage that they are most vulnerable. Maybe because of this females exhibit some parental care.

Most crustaceans release their eggs into the water and do not care for them. Crayfish females carry their eggs on their swimmerets to protect them from predators and here they hatch as perfect miniatures and go through three molts before releasing and taking up free-living lives, thus increasing their survival rate.

They reach sexual maturity in about two months and probably live up to three years although chances of surviving that long are pretty slim. There are sharp beaks everywhere. Females in their burrows are egg laden at the end of the dry season and young crayfish are very quickly able to repopulate newly flooded prairies. This makes them critical prey for wading birds in the lag before fish species appear in any quantity.

photo by Rose Flynn

photo by Rose Flynn

Crayfish are a vital component of Fakahatchee’s food web by dint of both their sheer numbers and because virtually anything that can catch a crayfish will eat it. There are at least 40 species of vertebrates that feed on them: from fish to pig frogs, water snakes, young alligators, raccoons and wading birds. They are a particular favorite of ibis who use their long curved bills to probe for them. On my visit the exposed mud was still pitted with holes from their foraging.

The numbers of crayfish tend to increase with the plant community’s complexity as this provides both shelter from predators and increased food resources. True to form, where I first stepped on to the denuded beginning of the Prairie, I was observing about 2 – 3 burrows per square meter, but by a quarter of a mile in, where there was more vegetation, up to eight, and remember this was after the feasting of the dry- down when the population is at its lowest.

crawdad image

But their role as a food source is only part of their importance. In wet prairies they may be considered a keystone species with a role analogous to that of the gopher tortoise in the pine flatwoods, but on a miniature scale. Crayfish burrows serve as refuges for many other small aquatic organisms that retreat to them as the prairie dries and then quickly repopulate it when water returns. Also by heaping up piles of earth they are creating perfect habit for seeds to grow where fire has not exposed the soil. Whatever name you call them: crayfish, crawfish, crawdaddies or mudbugs, crayfish are a vital part of the Fakahatchee’s ecosystem.

Taking Stock of Fakahatchee’s Prairie Hammocks

by Patrick Higgins

Typical small hammock on Lee-Cypress prairie to the west of Janes Scenic Drive.

Typical small hammock on Lee-Cypress prairie to the west of Janes Scenic Drive.

Late this spring during a chance conversation with Karen Johnson at the ranger station’s newly-planted butterfly garden I was outed as a ‘cryptobiologist’. By that I don’t mean someone who goes in pursuit of mythical creatures like Sasquatch, but rather someone who has trained as biologist but never practiced as one. As Karen’s eyes lit up I could almost see the thought bubble with the word “RESOURCE” flashing in it. She quickly pounced and the next thing I knew I was meeting Park Biologist Mike Owen to discuss a couple of projects tasked by Tallahassee on his ever-growing, but completely under-resourced, ‘to-do’ list. This was the beginning of the Prairie Hammock Survey.

When we think of the Fakahatchee we tend to focus on the Strand itself but there are seven main prairies within the Preserve. These are wet prairies – the least flooded of any Florida marsh type covered by water for only a few months of the year. They are also very species rich, even without taking into account the myriad of tree islands (hammocks) dotted across them. These develop on limestone outcrops that raise them slightly above the surrounding terrain and are mini-ecosystems in their own right. Their drier ground, abundant food supply and cover make them important resources for wildlife, but the Park does not have a lot of data on them.

That’s where the Prairie Hammock Survey comes in. It will provide data for input into the Park’s Burn Zone Map. Hammocks containing oaks are of particular interest because their acorns are an important food source for white-tailed deer, which in turn are the favorite prey species of the Florida panther. Acorns are most abundant on the ground from October through December when the nutritional value of the prairies’ other plant species are at their lowest. Knowing which hammocks are important for acorn production feeds in to the Park’s panther management objectives, although acorns are also an important food for the Florida black bear, as well as wild turkey, gray and fox squirrels, mice, voles, rabbits, raccoons, opossums and foxes. The survey will help the Park identify which hammocks should be protected when the surrounding prairie is subject to rotational (prescribed) burning and will also provide a baseline for detecting and monitoring any changes in species composition over time.

A typical survey day is on foot and often begins by wading waist deep across the borrow ditch after a careful check there aren’t any alligators lurking nearby. Once on the prairie during the wet season, and this is a very wet one, water is usually calf deep except in the hammock interiors where you have to be alert for other critters seeking dry feet or bellies, as the case may be. Rose Flynn has been joining me recently and adding her knowledge of the Fakahatchee. So far we’ve concentrated on Lee-Cypress, Copeland and West Prairies. When we’ve collected enough survey data we may see trends in species composition. But you only have to look at a close-up of the Park on Google Earth to see that that there are an awful lot of hammocks. It’s rather like painting the Brooklyn bridge.

Each hammock is surprisingly different and brings a sense of discovery. We record its latitude and longitude, write a brief description, photograph it, measure its circumference, calculate its canopy height, do a transect, tabulate the quantity of each tree and shrub species, as well as log water depth, wildlife sightings, bromeliad and ferns present, and note nearby blooming flowers. This usually involves circumnavigating each hammock 3 or 4 times, so we cover a lot of ground, but the real time involved is getting there. Some of the prairies are quite remote and just to do one or two hammocks can take a whole day, especially when you are diverted by an interesting spider or some other natural marvel.

Still, it’s a privilege to be able to tramp across such a beautiful landscape, even more so when there’s a purpose to the trek, and as a new member of the FOF Board it’s a fine opportunity to ‘learn’ the Park. Besides, there is something about open spaces and big skies that appeals to the human psyche – perhaps because mankind evolved in a similar savannah environment.

Photo by Rose Flynn of Patrick carrying survey gear on the way to the prairie.

Photo by Rose Flynn of
Patrick carrying survey gear on the way to the prairie.

Patrick Higgins has been tromping around the Fakahatchee since 2004 and has helped with FOF Coastal Cruises and Ghost Rider tram tours as an expert interpreter. He operates his own eco-tour company, TropicBird Ecotours+.

 

The Problem with Pythons

by Dennis Giardina

It could be said that if you haven’t heard about pythons in the Everglades yet, you’d have to have been hiding under a rock. If that rock happened to be in South Florida, you may still have become aware of the presence of pythons because there’s a chance you’d be sharing that cool, dark shelter with one of them. Over the past ten years there have been many very good articles written about pythons. There have been interesting, informative vignettes on radio and television programs but now it seems that the hype machine is rolling wide-open, pummeling hapless consumers of information with sensational anecdotes and images of an invasion of giant, malevolent snakes. The reality of the situation may be somewhat less shocking than portrayed by the sensationalistic media but no less concerning, albeit for different reasons. Let’s start close to home. Are there pythons in Fakahatchee and, if so, what threats do they pose?

Yes Virginia, there are pythons in Fakahatchee. We know this because one was collected by an exotic plant treatment crew in January of 2007 at the borrow pit lakes area in the northeast corner of the preserve. Another was observed floating upside down in the canal on the south side of US 41 by Mike Owen about a month ago, most likely hit by a vehicle. The epicenter of the spreading population of Burmese pythons is Everglades National Park. There are several theories of how they got there but whether the population originated by a breeding facility destroyed by Hurricane Andrew or as a result of multiple separate releases or both – the damage has been done. That SE Florida population has now spread in every direction aided by the network of canals that crisscross South Florida. For the past ten years Burmese pythons have been observed and collected in SW Florida, especially in the Collier-Seminole State Park – 6L Farms – Rookery Bay NERR – Marco Island Airport area. Some suspect that this SW Florida population may be the result of a separate introduction of Burmese pythons but regardless, there seem to be more sightings and collections every year. Mike Owen and I feel that the number of pythons that occur in Fakahatchee at this point is very low, filtering in up from US 41, down from I-75 and over from Big Cypress. We have yet to receive a report of a python on Janes Scenic Drive. When that happens, we will have to reconsider our population estimate.

The threats that pythons pose have more to do with their impact on native wildlife, especially local mammal and bird populations and less with any direct danger to humans. Pythons are not accustomed to eating us and even the largest Burmese pythons would have a hard time getting their jaws around even the narrowest of human shoulders to swallow one of us. They, like any animal, when threatened or cornered will defend themselves. Their bite/constrict/swallow feeding behavior is different from their defensive behavior which is more like other snakes: they coil up, inflate their body and raise their head, making a loud hissing sound. There are few animals (other than humans) that would continue to approach a large python in full-blown defense display but if one were to do so, the python would then strike repeatedly. Unlike animals, human beings usually wear clothes and if the curved teeth of the striking python were to snag a pant leg or a shirt sleeve, the python would not be able to simply release it and would try to pull its head back into its coils and perhaps it would go into wrap and constrict mode. I don’t know but if you are afraid to walk in the woods because of the danger of being bitten or eaten by a python, all I can say is don’t be, they are not going to bother you.

Skip Snow, the Wildlife Biologist at Everglades National Park who has been dealing with pythons longer than anyone, has noticed something concerning. It seems that small mammal populations, everything from marsh rabbits to bobcats seem to be on the decline along the main road inside the park. In areas where there were numerous sightings and sign of animals like tracks and scat, now seem to be much less or absent. Because circumstantial evidence does not a case make, Skip, UF Scientist Frank Mazzotti and others have embarked upon a study to see if they can prove that this observed decline has been caused by pythons alone, or whether its due to other factors like disease – or both. It’s hard to imagine that a population of pythons, likely numbering in the thousands wouldn’t have a noticeable impact upon a native mammal fauna unaccustomed to their predation but it’s our job to back up our feelings, insights and observations with data. That is science and there is (in terms of the physical world) no better arbiter of truth.

It seems to me and most of my colleagues that pythons and other large exotic reptiles like monitor and tegu lizards are here to stay. We think they will continue to spread, eventually throughout the entire peninsula. Cold weather events will knock them back, but they will self select for more cold hardiness over time as well. Native mammals and birds will have to develop strategies to avoid being eaten by them so that enough of them are able to reproduce and persist as species. Natural areas managers and scientists will continue to innovate methods to trap and kill them to keep their population levels low and reduce the average size of individuals but there is no magic bullet. There are however many tools in the toolbox. One particularly promising one is the use of dogs trained to sniff out pythons. A pilot project last year, using two Labrador retrievers from the Auburn University Canine Unit showed that in certain applications they were tremendously successful at locating hidden individuals and with targeted seasonal surveys, many pythons could potentially be removed from the environment in a short amount of time. Currently there is so much information available that if you want to read more, Google “Burmese pythons in Florida.”

Dennis Giardina is the Everglades Region Biologist for the Florida Fish and Wildlife Conservation Commission and was formerly the Park Manager of Fakahatchee Strand Preserve.