Wednesday, October 15, 2014

Honeymooning with the Fiddler Crab

Florida beaches and marshlands are home to three species of fiddler crab, the sand fiddler (Uca pugilator), the mud fiddler (Uca pugnax) and the red-jointed or brackish water fiddler (Uca minax), in the order Decopoda – meaning 10-legs. Two of these “legs” – the front ones – are adapted as claws, however. The males are easily identified by their one oversized front claw, which can weigh up to one-third of the crab’s total. Accounts differ as to the origin of the name, “fiddler.” One explanation claims the name came from the use these crabs make of their smaller front claw to eat. The motion of picking up its food, depositing it in its mouth, and placing discarded bits back on the ground resembles the bow action of a fiddler. The male’s one outsized claw is useless for that purpose; he eats (or fiddles with his food) one-handed, while the female is free to gobble her meal with both hands.

The adult fidder’s notion of “food” includes the algae, bacteria, fungus, and decaying matter in sand, which the crab picks up with the “eating claw”. Edible material is separated from sand in the mouth; the discarded “sandballs” are deposited back on the ground. Because of this diet, fiddlers are important as regulators of bacteria and fungus in beach and marsh. The tunnels they dig in the intertidal zones and mud flats provide them with shelter when the tides rise and also aerate the ground, further ensuring the health of those soils.

With such a large claw, you’d think that the male fiddler would be an aggressive fighter, but not so. That large claw is better adapted to waving than fighting. One male waves it at another potentially threatening male to intimidate it; this waving seldom progresses to the fighting stage. The larger the claw and the more vigorous the wave, the better the chance of intimidating one’s opponent. If the crabs do engage in physical combat, the vanquished crab risks losing that precious claw and having to regrow another, which never reaches the size of the first.

Size matters, not only in deterring threats, but in attracting females. A male will use his large claw to dig a spacious “honeymoon suite” for his intended; the bigger the claw, the bigger the suite. Once the suite is dug, the male will station himself at the entrance and wave that claw at passing females, signaling his vitality with his healthy waving motion. If he catches a female’s eye, he will “dance” toward her and retreat back to his suite. If she takes a few steps in his direction, he taps on the wall of his burrow, so there is no mistaking his intentions. He waves again and repeats the dance of approach, retreat, and tapping the entrance – each time enticing the female closer until she finally follows him in. He then seals the entrance with mud, and mates with her. The couple stays in their honeymoon suite for two weeks, at which time the female’s eggs have gestated. She leaves the love nest to deposit her eggs, while he prepares his “digs” for another “wave” of wooing the next “lucky lady”. The male’s courtship behavior has earned it another nickname – the “calling crab.” And while it seems that for a female, her mate’s claw size does count, it may not be that simple. Research has shown that the size of the “honeymoon suite” influences its internal temperature, and that temperature influences egg gestation. The bigger the claw, the bigger the construction, and the more suitable the temperature might be. Perhaps the male’s tapping helps the female judge the size of the accommodations. She may be judging the spaciousness of the digs as much as she’s sizing him up. With summer and the mating season over, you might be able to spot the resulting juvenile fiddlers as well as their very tired parents at the GTM Research Reserve.


Wednesday, September 17, 2014

A Coastal Triathlete: Brown Pelican

Photo taken by Cindy Elder
If you've ever taken an auto trip, you've probably seen bicyclists riding closely behind each other in a straight line. This technique, called a "pace line," allows the riders an opportunity to "draft" the cyclist just in front, cutting down wind resistance for subsequent riders. And if you've walked one of our beaches you probably have seen brown pelicans, Pelecanus occidentalis, flying in a similar formation. What those pelicans do instinctively takes most bicyclists weeks or months to perfect. For a brown pelican that can weigh up to 15 pounds, it's truly an energy-saving technique, allowing these birds to ride the marine air currents, rising and falling with the waves, with minimum effort.

Brown pelicans can be found from the coasts and estuaries of the mid-Atlantic and around the Gulf of Mexico. Some groups may migrate several hundred miles during the year, while others live their lives around the same shorelines. Whether they migrate or not, pelicans are never far from land and relatively shallow water depths. These are the areas in which they feed and breed. And if you think the pelican pace line is a pretty savvy way to get around, you'll be impressed at their fishing technique. A pelican's method of catching fish can be compared to a defensive end's approach to tackling the runner in a football game. Both dive right at their target with head tucked, and in the case of the pelican, with a slight rotation to the left (to protect the trachea on the right side of the bird's neck). The impact of the hit stuns the target (in the football game it at least shuts down the ball's advance toward the goalposts). The pelican's goal is to consume the fish knocked unconscious by the force of its collision with the water. Both the defensive end and the pelican have their protective equipment. Shoulder pads and a helmet for the man, air sacs beneath the pelican's skin that inflate like little air bags.

P. occidentalis is not a dainty eater; it expands its trachea, quickly taking in both fish and water before the fish recover from the blow. Nearby seagulls flock to the dive site, knowing the pelican must open its bill upon surfacing in order to rid itself of the water before swallowing its meal. The gulls will attempt to literally snatch the food out of the pelican's mouth; the ensuing scramble is reminiscent of the post-play pile-ons so commonly seen in football. Considering how last Sunday's game went against the Eagles, our Jacksonville Jaguars might benefit from a lesson in tackling given by P. occidentalis.

Come to the GTM Research Reserve's Family ecoMENTALITY National Estuaries Day on September 27 and you'll be able to watch this triathlete's skill: flying, and fishing, and the diving play-by-plays of pelican vs. gull right at the estuary's line of scrimmage.


Wednesday, September 3, 2014

All about that bass, no treble...hooks

Sciaenops ocellatus: Fried, Baked, or Blackened

If you saw this notation on a restaurant menu, would you order it? If you said, "yes," you know your redfish! Red Drum, commonly called, "redfish," "channel bass", or "spot tail," are popular restaurant faire, and no Cajun restaurant would open its doors without offering it to customers. This local fish is also a favorite of saltwater sports fishermen - so much so that states set annual catch limits to protect it from being overfished. Whether you like to catch it or eat it, you should thank your local estuary for its role in this fish's life cycle.

Red drum females mature at 4.5 years of age. The males do so around 3.5 years. Between August and December the drums leave their coastal habitat to gather at the mouths of inlets to spawn. The males use muscular contractions to vibrate their swim bladders, making a drumming sound. Apparently the females enjoy the noise; they can release up to 1.5 million eggs per batch. That's an enthusiastic response. Fertilized eggs are carried by the tides into an estuary (like the GTM Research Reserve estuary) to spend the next three or four years eating small crustaceans and marine worms. When mature, S. ocellatus heads out to join the other adults at the coastal "drumming session". Both sexes "drum" their swim bladders when agitated; that behavior has earned them the fisherman's name of drum.
The redfish you'll see listed on a restaurant menu are probably not wild caught. Red drums are typically grown as aquaculture. If you want to see one in the wild, but don't want to get a license and a fishing pole, sign up for a Family Seining activity as part of National Estuaries Day, Saturday, September 27, at the GTM Research Reserve. Maybe you'll find a juvenile in your net!

Wednesday, August 27, 2014

The Mosquito's Fall Love Song

August is prime mosquito breeding season, and northeast Florida is in the bull’s-eye with over forty species calling this area "home." There are a number of myths about mosquitoes, including the mistaken idea that they can transmit HIV. They can't. There are a number of very problematic illnesses they can transmit, including Eastern Equine Encephalitis (EEE) from the virus (EEEV) by that same name. EEEV can infect both humans and horses. The salt marsh mosquito (Aedes sollicitans) is one vector of transmission, and this particular species is a difficult one to control given its life-cycle.

A. sollicitans is found in salt marshes. Like other female mosquitoes, the salt marsh mosquito needs a protein-rich feeding in order to lay eggs. Typically the female A. sollicitans seeks blood from a mammalian source, including humans and horses. After she has fed she can travel for miles looking for a low-lying, but dry patch of ground in a salt marsh. The eggs need four or five days of dry warm weather, then must be inundated by water that the next very high tide washes in. Eggs laid in the fall can overwinter awaiting the next favorable condition for hatching. The resulting larvae feed and molt several times, then enter a pupal stage before emerging as an adult. Depending upon temperature and other conditions, the mosquito's life cycle can last anywhere from a few days to two weeks. Since the salt marsh mosquito breeds in marshy areas, it is impractical for humans to control its breeding. Mosquito Control Districts, such as Anastasia, use chemical means to reduce populations.

As of this writing, there have been no known human or equine cases of EEEV in St. Johns County. Clay has had several equine cases, despite the fact that there is a veterinary vaccine for the disease. Unlike some species of mosquito, the salt marsh mosquito cannot host the EEEV. It can only transmit the virus after coming in contact with an infected bird. (If A. sollicitans cannot find a mammal, it will obtain blood feeding from a bird.) Because birds act as virus reservoirs, they can serve as indicators that the EEEV is present in a given area, and therefore, transmittable to humans or animals. Typically chickens are used as "sentinels" since they can be sequestered during the summer months and periodically tested for virus antibodies. These "canaries in a coal mine" are our first warnings to take serious precautions against getting bitten. However, precautions are prudent year-round in Florida. So when enjoying this beautiful fall weather on the GTM Research Reserve trails don't forget to bring effective insect repellent and protective clothing!

Now for two weird facts about mosquitoes.
  1. They do not have lungs: they breathe through openings in their chest or abdominal exoskeletons. 
  2. They "harmonize" their wing beats as part of the mating ritual. Yes, that annoying whine is music to a mosquito's ears. In the case of a related species, A. aegypti, the male slows its 600 beats-per-second (bps) while the female increases her 400-bps so they produce a combined total of 1200 bps: the perfect love song. After mating the female will be ready for her "protein drink" - preferably fresh blood. This mating and breeding behavior has inspired some scientists to call it the "Whine and Dine". It's possible that away might be found to disrupt the whining that initiates mating. Perhaps if more mosquitoes were tone-deaf we could reduce the need for our Mosquito Control District's services and still prevent mosquito-borne diseases.

Sources diseases/_documents/2014/week34arbovirusreport-8-23-14.pdf

Wednesday, August 13, 2014

Animal Connections - Eastern Indigo Snake

Eastern Indigo Snake

Drymarchon couperi, the Eastern indigo is the longest native snake in North America. Larger males can reach eight feet in length. Although it prefers tropical climates, the indigo extends its range throughout the Florida peninsula to southeastern Georgia by using the burrow holes of large animals such as the gopher tortoise (Gopherus polyphemus) during colder weather. Burrow holes are also important for indigos "shedding their skin" no matter what the latitude. And as the gopher tortoise species goes, so goes the Eastern indigo. Both are Threatened Species in at least one of the areas where they are found.

A burrow is a necessary, if temporary, shelter for this snake. It does not hibernate, but continues to hunt and feed outside the burrow throughout the year. And it dines on anything it can overpower, from fish to small mammals. It doesn't wait until its victim has expired - merely incapacitated. In short, it's not a fussy eater. It will even eat juvenile gopher tortoises (which seems a bit self-defeating). The indigo is not venomous, but it is resistant to the venom of snakes that are. An Eastern indigo can survive the bite of a copperhead or rattlesnake and subsequently consume either without ill effect. Not only is that trait advantageous, it's downright necessary because venomous snakes also take shelter in gopher tortoise burrows. There's only so much room down there...

If you've seen a picture of an indigo you might rightly wonder why it has the appellation, "indigo snake."
The scales of the snake refract sunlight to give its body a shimmery blue-black appearance, although that doesn't always show up in a photo. When seen in the shade, the iridescence is lost; and the snake looks like any other (large) black snake. The snake's taxonomic name, "Drymarchon," roughly translates into "forest ruler." Large and powerful as these animals are, it seems apt. Its other common names, "gopher snake," or "blue gopher," reflect its choice of gopher tortoise burrows for shelter.

Eastern indigos do not mature until three or four years of age - relatively late in the snake world. Females, when ready, will emit a pheromone to attract a male. If multiple males pick up on the scent then they battle for the female by intertwining their bodies trying to pin the other's head to the ground. Females lay about a dozen eggs, preferably in the shelter of an abandoned gopher tortoise burrow. The slow maturation rate of the Eastern indigo and its dependence upon the gopher tortoise for sources of shelter make resurgence of this species a complex goal. Snakes may not be on everyone's "favorites" list, but Eastern indigos, like all members of the Serpentes families, keep populations of smaller animals in check. Protecting its place in this world will involve allowing both the Eastern indigo and the gopher tortoise that benefits it sufficient habitat to survive.

Tuesday, August 5, 2014

A Rose is a Rose, is a Roseate Spoonbill

A Rose is a Rose, is a Roseate Spoonbill

If you've ever seen a flamingo in North Florida, you are mistaken. What you saw was a roseate spoonbill (Ajaja ajaja). Flamingos don't venture north of the Florida Keys. You might say the roseate spoonbill is North Florida's version of the flamingo. The flamingo and the roseate spoonbill look very much alike at first blush. Their rouge plumage is colored by the tiny pink crustaceans they both eat. It seems scarcely possible, however, that any other bird could look as comical as the long-legged, hook-billed flamingo. But the roseate spoonbill does. In fact it looks downright wacky. Imagine a pint-sized bald flamingo with an olive and tan pate and a black streak at the base of its skull, just above the feather line. And picture this three-foot avian looking like it ended up the worse for wear in a boxing match - that a first round knockout punch to its hooked bill had flattened it into a spatula. Now you're visualizing the roseate spoonbill.

But don't expect to laugh when you see one. Its amazingly beautiful plumage makes its silly face seem unimportant. A bill that would make a duck blush is more than compensated by its ruby-tipped wings, shoulders sporting a circle of orange feathers, and its pink and white plumed chassis. Seeing a spoonbill in flight, its 4-foot wingspan floating like a pink cloud against an azure sky, you could overlook the strange red eyes and a forehead not unlike Mr. Magoo's. Mrs. Magoo looks no different. Perhaps a tad more diminutive and a shade less rosy.

Its beauty and its whimsy aside, seeing one is so special because this bird has made an astounding comeback from the 30-40 breeding pairs that constituted its population in the 1930's. Fashionistas at the turn of the 20th century had been captivated by the bird's feathers and coveted them for ladies' fans. The fact that this appropriation shortened the bird's lifespan was of little regard. The demand for spoonbill feathers was assured because once the feather was removed from the bird, it was removed from the source of its coloration. Older spoonbill feathers faded, and new ones were sought to replace them. Luckily the bird was placed off limits to hunters when it was listed as an endangered species. And fashion being a fickle maiden, moved on to another craze.

Today there are thousands of nesting pairs of spoonbill in Florida and an abundance in Texas and Louisiana. Northern Florida is the extreme edge of its range. If you head over to the St. Augustine Alligator farm towards the end of March, you can see them swoop in droves to court, nest and raise their young. The photographers are already there, anticipating the spoonbills' arrival while snapping happily at wood storks, egrets, and herons. Amid this ruckus, the gregarious spoonbills pair up and share parental responsibilities for two months, until the fledglings are ready to leave the nest and the sanctuary of the Alligator Farm. (The alligators at the
Farm deter the typical spoonbill egg predators such as snakes and raccoons). After a steady diet of crustaceans and other delicacies, the young birds take on the trademark pink, orange, and red hues of adult spoonbills. And their bills flatten out to resemble those of their elders.

Keep an eye out for roseate spoonbills when visiting the GTM Research Reserve in warmer months. Its estuaries harbor the wide variety of small animals these birds consume. In addition to small crustaceans, spoonbills eat slugs, snails, small fish, and insects. They dine communally, and catch their meals by immersing their bills vertically while swishing them through the water. It's quite a sight to glimpse a group walking in unison back and forth in the water, heads swaying to and fro, snacking on what crosses their path. Their nostrils sit high up on their bills so they can breathe while foraging. If a small animal is within striking distance their pressure-sensitive bills alert them to the potential meal and snap it up. The water they wade through is often murky because the spoonbills intentionally agitate it to rouse their prey. They rely more on bill sensitivity than eyesight to score the next mouthful.

Colorful, sociable, and resilient, these wading birds are as striking as flamingos, and even droller. But they have retained one scrap of dignity that the flamingo lost. They haven't been made into lawn ornaments - yet.

Great Florida Birding and Wildlife Trail - Roseate Spoonbill

FWC - Roseate Spoonbill

St. Louis Zoo - Roseate Spoonbill

10 Fun Roseate Spoonbill Facts

Smithsonian National Zoological Park - Roseate Spoonbill

Wednesday, July 2, 2014

Respect the Turkey!

This week we observe the 238th birthday of American Independence. In this modern era it is commonly believed that if one of the signers of the Declaration of Independence had had his way, we'd be celebrating, not the American eagle, but the American turkey, as our national bird. Benjamin Franklin is thought to have preferred that the North American turkey rather than the eagle be depicted on the Presidential Seal, and that he justified his preference on the turkey's uniquely indigenous status and upon its "moral superiority" to the eagle. Not exactly. The elder statesman expressed his opinions on the subject in a letter to his daughter saying, “For my own part I wish the Bald Eagle had not been chosen the Representative of our Country. He is a Bird of bad moral Character. He does not get his Living honestly." He continued, "... the Turkey is in Comparison a much more respectable Bird, and withal a true original Native of America… He is besides, though a little vain & silly, a Bird of Courage." He added that the eagle on the seal looked "more like a turkey," and that observation pleased him. Thus, the seeds of confusion were sown. The popular belief has taken such deep root that even the National Geographic reports the myth. According to the Franklin Institute, Ben's choice for the national seal had no bird on it whatsoever.

But let's take a moment to understand the wild turkey's "respectable" qualities, and to examine Franklin's claim to its status as "a true original Native of America." Keep in mind, this is the North American wild turkey, Meleagris gallopavo, not the behemoth domesticated turkey that dominates our Thanksgiving tables. Domesticated turkeys have a more "complicated" lineage. They are the products of intensive breeding to produce a hefty bird with plenty of breast meat. The birds are so large they can hardly walk, let alone reproduce; artificial insemination takes care of that function, and ensures a standard-unit gargantuan turkey as its result.

In contrast, North American wild gobblers (male turkeys) weigh only a third of their farm-bred brethren, between 16-24 pounds; females average 8-12 pounds. One or more subspecies of wild turkey occupies every state in the continental US, and parts of Canada and Mexico. It's hard to believe that these birds were on the brink of extinction in the 1930's, but thanks to conservation efforts, especially those of hunters, they have made a dramatic comeback. The Eastern wild turkey, M. gallopavo silvestris, has the widest distribution, from Canada to north Florida and west of the Mississippi. Florida has its own subspecies, M. gallopavo osceola. Named after the Seminole chief, Osceola, this bird occupies the panhandle, and depending upon which source you reference, the counties south of Duval. Three other subspecies occupy states from the mid-West to the West Coast. Whatever the experts say, a turkey goes where it pleases. Which is why turkeys were herded just like cattle when brought to market, back in the 1800's.

Turkeys are social creatures; within a flock, each individual has its own "pecking order," no pun intended. They have a wide variety of vocalizations used to communicate danger, pleasure, and communion to each other. When a group of them gets together at night they can sound like a heathen cult celebrating a sylvan festival. So much for a simple, "gobble-gobble." A mother turkey will vocalize to her chicks, making clucking sounds before they hatch to help them imprint on her, thus aiding her instruction of them in basic survival techniques. Sounds like a pretty respectable critter so far.

While the domestic turkey is physically incapable of the act of reproduction, the male wild turkey takes this responsibility very seriously. During breeding season, males become more colorful; the head and feathers may undergo several color changes. Their waddle and the tubular snood that drapes its bill enlarge and brighten. They also vocalize and dance while fanning out their tail feathers. All to attract the drab little females.

At the author's home, the breeding season for our own backyard visitors takes on a bar-scene atmosphere. The dominant gobbler will clear a circular patch of ground for his performance stage. Within it he will dance and fan his feathers in a display that is obviously proof of his physical stamina. The ladies will stare across the pond with their backs to him, in feigned indifference. When the excitement gets too much for one damsel, she will try to break away from the group and sneak off with her Romeo. It's then that the turkey pecking-order becomes evident. The dominant female will hustle off to collect the wayward bird and bring her back to the fold. After a respectable amount of time elapses, the dominant female then struts over to his highness and they leave the scene together. He'll be back for the others later. Meanwhile the immature males are running circles around any female in sight, hoping perhaps to exhaust her into submission. Try again next year, sonny.

At least Franklin's notion that the turkey is a true New World indigenous animal must be correct. Not entirely, as it turns out. Until Europeans arrived in the New World there were two species of native American birds: one in Central America and another ranging into Canada. When the Spanish encountered native peoples raising the Central American species, they mistakenly believed them to be a variety of grouse from Turkey and misnamed them "turkeys." They brought the New World birds back to the Old and bred them; 200 years later the colonists reintroduced them to the Americas as domesticated animals. Farmyard turkeys are hardly the true native originals Franklin thought them to be.

European Americans had no corner on myths about the turkey. Native Americans had many stories involving turkeys or explaining aspects of their appearance or behavior. Turkeys could be tricksters and thieves, or noble characters that aided people in distress. Feathers and other parts of the bird could convey special powers on the human wearer.

So, the eagle never was in danger of losing its status as the official bird of the United States. Just as well, too. When Apollo 11 made the first manned visit to the moon, the crew landed in a vessel named for our national bird. How very different the report from Neil Armstrong, "The Eagle has landed," would have sounded if our national bird had been the turkey.

Enjoy the 4th of July, but please remember all those fireworks cause wild turkeys, eagles, and other creatures a great deal of stress - not to mention the hazards of explosives and the post-celebration litter. Even if the turkey is not the noble creature of Franklin's estimation, it and its fellow creatures deserve our respect on holidays and every day. And decide for yourself which of these birds has the better "character" - read our April 9 Facebook post on the eagle as a National Symbol.