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