Birding by RV, ch 5, Dry Tortugas

 

Our timing in Florida, although tied to birds, indirectly held Linda and me to a schedule causing us to endure more of Florida’s late spring weather than we wished to experience.  Rising temperatures become uncomfortable white we wait to attend a birding tour of the Dry Tortugas. Earlier tours were full and we did not want to leave Florida without the ultimate birding location that harbors so many species found nowhere else than at the Dry Tortugas. img_3871

Much has been written about the islands some 70 miles west of Key West. The region is ripe with history.  Ponce de Leon, in 1513, named his discovered islands Dry Tortugas since sea turtles inhabited the arid islands. Pirates used the islands as a base from the 1600s to the 1700s. A lighthouse was built on one of the islands in 1825. Construction of Fort Jefferson, named for Thomas Jefferson, began in 1846. Sixteen million handmade bricks, mostly set by slaves, formed the six massive walls of the 45-foot high fort. Within the thick walls are 2,000 supporting arches. Although built to stave off invaders, none of the forts’ huge cannons fired a shot. During its military period, over 1,700 people lived on the islands. I am not sure how many guns were planned for the fort’s arsenal, but I read somewhere that the battery of cannons was reduced from around 400 to a mere 141 cannons. Regardless, by the mid-1800’s, the invention and use of new types of guns and ammunition capable of penetrating the brick walls rendered the fort obsolete as a barrier to invasion.

Fort Jefferson, controlled by Federal forces, before and after the Civil War, eventually became a prison. By 1863, the number of white prisoners replaced the need for slave labor. In 1865, the prison mostly held Army deserters that made up about half of the 1,000 occupants of the fort. Incarcerated at Fort Jefferson were four prisoners accused of conspiracy to assassinate President Lincoln. Among them was Dr. Samuel Mudd, who, by no means was an abolitionist, was later pardoned for any conspiracy. The fort, which was never completed, became an unjustified military expense. Fort Jefferson was abandoned in 1874. In 1888, the military turned the facility over to the Marine Hospital Service for a quarantine station. Garden Key was a coaling station for ships during the Spanish-American War in 1898. The island also served as a wireless station and a seaplane base in WWI and soon abandoned for the last time by the military. The islands were under the Department of Agriculture as a bird sanctuary in 1908, and protected under the Department of Interior as Fort Jefferson National Monument in 1935 and as Dry Tortugas National Park in 1992.

Eleven islands were part of the coral atoll known as Dry Tortugas. Today there are only seven sandy islands or keys that sit on the shallow 300-foot deep continental shelf jutting from the mainland. How many, if any, will remain as climate change causes sea levels to climb. Projections show many drowned islands, with considerable habitat lost to the ocean. Not far beyond the submerged continental shelf, the ocean plunges to around 10,000 feet in-depth. Sand, shifting from normal currents and weather such as hurricanes, continually changes shorelines and channels between keys.  

Ornithologically, the tiny islands are rich in diversity and unique by providing breeding grounds for several tropical species not found on the mainland and a stopping off place for migrants. We can hardly wait. 

*****

23 April 2015

We took our time leaving Everglades National Park yesterday. Because of the late hour in departing, we decide to bunk at the Wal-Mart in Homestead before heading to Key West. About two weeks ago, we drove to Florida City, the town immediately south of Homestead, to pick up our mail. We chose Florida City since it is on the highway going to Everglades National Park and the size of the town relative to Homestead should be easy to negotiate and find the post office. However, the post office at Florida City does not accept general delivery mail, but they had sent our mail to the Homestead post office. Directions to the Homestead PO were a bit garbled, but after a u-turn or two, we arrive and pick up a grocery sack of mail containing paper statements assuring us that the auto-pay is working.

It is too late in the day to drive to Key West. There is no need to drive back to Florida City since, since we learned two weeks ago, Florida City has a strict ordnance against parking an RV. Luckily, we found the invisible line dividing Florida City and Homestead and a legal place to spend the night.

24 April 2015

Wes Biggs, our trip leader to the Dry Tortugas, designated today as Day 1, which includes driving or somehow otherwise transporting to Key West, listening to the orientation and finding the bunk on board the 100-foot Spree, the boat to float us to a Florida birding mecca.  Our drive down the Keys from Homestead is uneventful.  The amount of traffic is surprising and degree of development on the islands is distressing.  Human occupation of the keys has mushroomed by the thousands, with populations increasing from 1960 by a magnitude of seven. Naturally, I did not expect to step back in time to 1962 when I drove to Key West, but 15,000 more residents on these small islands today are negative forces to the natural habitat I once enjoyed. So much is gone. More and more homes and business building support more and more people dredging shorelines for more and more boats has forever greatly altered nature of five decades ago. Fortunately, the high cost of living and building restrictions have slowed human “progress” to the point that what natural habit that is left may survive further encroachment. That is, further encroachment by humans might not be a concern, but predicted rising sea levels will be a major factor in habitat change. A scientifically crafted publication of the National Academy of Sciences whose headquarters I once passed during bus commutes to my museum, predicts southern Florida and the Keys will be under water by 2025. That is only ten years from now. Before that, tropical storms and hurricanes will more easily flood the lowlands. It is past time to be afraid.  

We arrive in late afternoon at Stock Island, the island immediately east of Key West. Linda and I try not to think about a decade from now and turn our minds from rising sea levels to directions our tour guide sent. At the end of a narrow road away from US 1, we arrive at a dock where the captain of the Spree greets us.  The 100-foot long and 22 foot wide hull of Spree is blue. Above, it is white; reminding us of a small version of the Alaska Highway ferry that we rode in 2013. A rusted boat tied to the dock next to the Spree appears ready to sink. Three men are repairing something, perhaps pieces of the rusty hulk, and another is directing a small, maybe 4-person boat onto a trailer. Meanwhile, onboard Spree, we see from the dock a couple of crew members sprucing up the mid-deck, the one we will board. We already know that once aboard, no one will be allowed to wear shoes to prevent tracking on the boat anything from land.img_3772

Captain Frank offers an electric plug-in, but to use it and have our RV out-of-the-way from activities on the dock would require an exceptionally long hookup. There is space between two nearby structures. We park there and wait since it is much too early to come aboard.  That allows Linda and me to organize better and to dream of things to come.  By 6 pm, members of the tour group are beginning to arrive and by 7 pm, everyone that is going aboard is going aboard the Spree.  We bring our gear and find our berth below deck.   There are 24 berths occupied by crew and those of us signed up for the birding tour. Linda and I use the upper bunk for storage and soon, we are spooning in the narrow lower bunk.

25 April 2015

The Spree leaves the dock around 4 am.  That is before I am able to roust myself out of the cozy night’s quarters.  I recall hearing the motors slow and the muffled calls of some of the birders, but I do not remember anyone announcing Brown Booby.  By six, I am up and throw down a breakfast of scrambled eggs, biscuits smothered in gravy and a small piece of sausage.  The gravy and sausage are foods I do not normally consume and will not help me keep off the pounds I lost since leaving Oregon in late October last year. However, recalling the words of an old Navy chief once upon a time might help make the cruise pleasurable. He advised to eat a hearty breakfast to avoid seasickness.  

Deftly avoiding an empty stomach to prevent the chance of suffering unpleasantness from the rocking and pitching boat was not necessary, but what a great excuse to wolf down a big breakfast. The sea is smooth as we motor west on a course north of the Gulf Stream.  Climbing to the observation or sun deck is relatively easy.  Over half of the 22 people on the tour are standing along the rails or wandering from side to side as they apply sunscreen liberally and ascertain that their optics are clean and ready for the next bird.  In minutes, a Masked Booby appears.  Okay, my first new ABA species already.  A Brown Booby is with the Masked Booby.  My only other Brown Booby was a distant view of a confused bird just off the coast of northern California a few years ago.  The pair of boobies today is not suffering confusion; they are in their normal geographic range. A large bird appears several minutes later.  It completely throws me.  When I hear the identification, I at first think it is wrong, but when I play a couple of field guides in my brain, I realize that I am looking at a subadult Northern Gannet in tropical waters during spring.  I should get out more often.

Little Audubon’s Shearwaters begin to appear in ones and in small groups of four or five skimming the flat sea.  The birds disappear rapidly after they catch our eyes.  With my second new ABA bird, I do not rest as a Bridled Tern comes into view.  Thanks to someone with far more pelagic experience than me, I learn that Bridled Terns, although similar to Sooty Terns, are relatively easy to identify by their brown and slightly less defined patterns.  The Bridled Tern is with a group of Brown Noddy.  I wonder if I can keep count of all these new ABA terns.  The answer is yes, as Sooty Terns come into view.  This species has special significance for me. Briefly, I was offered a job with the Pacific Program (Pacific Ocean Biological Survey Program), but at the time was, you might say, was under contract with the Navy and never in the range of Sooty Terns. However, while still in the Navy, I volunteered my services to the Pacific Program to help sort data on different pelagic species, including Soot Terns. Later, as an employee at the museum, I measured and curated specimens of Sooty Terns for years.  To me, Sooty Terns signify being at sea, a lost job opportunity and, at the museum, becoming friends with many Pacific Program staff who had banded and observed countless Sooty Terns. If the Pacific Program would have had a mascot, it surely would be a Sooty Tern. Today is exciting. Today, I am seeing for the first time, live Sooty Terns.

We pass a shrimp boat and more and more open water and then, the islands, the Dry Tortugas coming into view. We are in Dry Tortugas National Park. Its 101 square miles protects coral reefs and wildlife surrounding the islands that occupy only 104 acres. A tall 150-foot Coast Guard lighthouse on Loggerhead Key, the largest island, is three miles to our west. Fort Jefferson sets massively atop 16-acre Garden Key. Bush Key, now connected to Garden Key by a narrow isthmus of pale sand, is off-limits in order to protect tern and frigatebird nesting colonies. It is a good thing, since a surprisingly large number of people, 60,000 in an average year, visit Dry Tortugas. Spree anchors offshore from Garden Key. Several other boats, including a tour boat and private crafts, anchor nearby, as does a seaplane. The zodiac the Spree has been towing is deployed and in about three or four trips, everyone on the bird tour is on dry land.

Sooty Terns continue to grab our attention. Individuals of this long-lived species may reach 30 or more birthday candles and spend years at sea. Sooty Tern is the most abundant tropical seabird in the world, with numbers ranging from 21 to 22 million individuals and, at this moment, I am watching thousands of them milling over a tern nesting colony. Just how many Sooty Terns are in view is impossible to estimate. The number of nesting Sooty Terns currently reported from companies providing transportation to the Dry Tortugas ranges from 80,000 to 100,000 birds. The more birds for tourists to see equates to more fares to charge. The number of Sooty Terns reported by investigators who have no stake in tourism is currently lower than those reported by commercial sources. Even so, seeing tens-of-thousands of Sooty Terns is phenomenal, and if a novice attracted by any number begins to care about birds and conservation, then, perhaps the commercial bend in truth might be worth it.

Historically, the number of Sooty Terns breeding at Dry Tortugas has undergone change. In the late 1800s, humans routinely collecting their eggs spectacularly depleted the population size. Only 7,000 nests were found in 1903, but since then, the population trend has been upward. On page 143 in “Wild America” is a statement that 95,438 occupied nests were reported in 1950. That turns out to be 190,876 individual Sooty Terns! Bill Robertson published a detailed account of Sooty Terns in a wonderful 95-page publication, “The Terns of the Dry Tortugas.” Anyone going to the Dry Tortugas should read the work, which was in the Bulletin of Florida State Museum, volume 8, number 1. It is also on-line at

https://palmm.digital.flvc.org/islandora/object/uf%3A39936#page/18/mode/2up. Bill discussed census data up to 1956 and stated that the number of Sooty Terns breeding has remained steady at about 100,000 since the high counts in 1950-51. In a 1999 memo, Bill Robertson wrote, “Sooty tern nests annually on Bush Key were studied intensively for 40+ years.  On-island behavior and population structure well-known, but no satisfactory recent estimate of colony size.  An educated guess might be 25,000 or 40,000 pairs.” I can almost hear Bill say the words in that memo. He might have sighed about the lower number of nesting Sooty Terns. Park biologist Sam Bass continued annual census of Sooty Terns at Dry Tortugas and counted 31,941 pairs nesting in 2001. Nesting pairs plummeted to a little over 10,000 in 2006 and only 3,800 the following year and the populations are now close to 20,000 pairs.

Why has the nesting population of Sooty Terns at Dry Tortugas changed? There are many answers. One is the method used in making estimates. Bill, in his 1964 study, for example, discusses errors in estimates made by Audubon and repeated decades later by Fisher in “Wild America.” Having made a few estimates of breeding seabirds some years after Audubon, I know there are right and wrong approaches to approximating bird populations, especially if the subject species appears in dense swarms. Many of the earlier counts were guesses. Later, far more accurate counts were not always conducted in the same manner and annual counts of birds were not always made during the same month. The high counts in 1950-1951 were conducted in late May. Bill noted in his study that the 1950-1951 data raised questions. He also points out that the timing of a census and the nesting stage of the colony are important in determining an accurate picture of the colony. Sooty Terns incubation period is about 30 days and fledging takes about 60 days. Timing of a census also plays a role for counts before and after hurricanes. For example, the low count for the colony in 2006 followed bouts of devastating hurricanes.

Ignoring errors in methodology, I wonder, did the nesting colony of Sooty Terns fall from some 190,876 birds in 1950 to about 80,000 pairs in the later decades. Have 110,000 Sooty Terns abandoned Dry Tortugas? Could introduced black rats be the culprit? Those pesky critters, once restricted to Garden Key, are now able to stroll across the sand to the tern colony on Bush Key. Those two islands were once separated by water. Probably a few rats backstroked their way to Bush Key and some may scurry across the sand connecting the two islands today. However, park investigators have not discovered predation by rats. Rats may have driven Sooty Terns from nesting on Garden Key decades ago, but I suspect humans may have played a greater role displacing breeding terns on Garden Key.

Terns and more over Bush Key           Brown Noddies at Garden Key

First is to consider is that rats are attracted to food scraps from campers and visitors. Second, visitation to Dry Tortugas has increased. Last year, 4,438 people camped at the campground. This year, the campground is full, but I did not notice exposed or scraps of food, but then again, I am not a gull although someone in seven decades of my life must have called me a rat. The number of non-campers spiked in the mid 1960’s and visitation has gradually increased since. Third, rats are not the only animal attracted to food scraps. Scraps also attract gulls and gulls may raid the tern colonies to feast on eggs and chicks. It is likely hungry gulls followed some of the multitudes of boats from Key West to Dry Tortugas. Did we lure the tern’s possibly worst predator to these islands? Has human curiosity evolved to the point of loving Dry Tortugas to death?  

Other, perhaps not so obvious reasons, may explain low populations of nesting Sooty Terns. For example, a 2010 issue of journal “Waterbirds” found predation to nesting Sooty Terns was greater when the amount of vegetation cover was low. Yes, birds that prefer to nest on the ground benefit from adjacent vegetation. The referenced study showed that when the 2005-2006 hurricane ravaged vegetation recovered, the number of nesting Sooty Tern numbers from 2008 to 2011 increased. Likely, other factors might influence nesting populations. As always, more study is required.

In addition to numerous variable concerning the population estimates and fluctuations, Sooty Terns are nesting about three months earlier than they did only fifty years ago. Fifty years ago, the species normally began nesting in April. No one has proven why the terns are nesting early. Sooty Terns breeding at the Dry Tortugas are the only species of bird in the Caribbean region known to have a similar advanced breeding schedule.

Graduate student Ryan Huang, with direction from ecologist Stuart Pimm, is working on the problem. Is the Sooty Tern of the Dry Tortugas a canary in the coalmine? Are these birds responding to human alterations to the habitat and climate?

Are the Sooty Terns signaling something drastic is happening to nature? Ambient temperatures are rising, oceans are warming and, just to name a few, sea levels are rising, and in some regions of the world, drought is increasing, wildfires becoming rampant during the spiral of climate change. Rises in sea-level will cause an inflow of seawater to mainland Florida and concurrently destroy fresh water marshes everywhere not to mention make most of the Florida Keys accessible only to scuba divers. That is the worst-case scenario. Just how much of a rise is not definitely predictable, but any rise will reduce shorelines of islands and worsen the impact of flooding from storm surges. Most certainly rising sea levels of the low keys of the Dry Tortugas will drown Sooty Tern colonies. That probably will not happen until after people begin using the Dry Tortugas as a stopover to Cuba, something the park has been worrying about for years. How much will the environment take before pushing back?

Now, the thought of climate change hits us even harder. We learn that one of the keys frequently disappears under water and that another island is no longer surfacing. In fact, other islands have disappeared. Linda and I also hear that the land bridge from Garden to Bush Key is the result of shifting sand. We had read that rising sea levels would not only reduce the sizes of the important nesting islands, higher water will undermine the foundation of Fort Jefferson. Of course, that is the tip of the melting iceberg. Rising water equates to more severe storms, changes in chemistry of the water and alterations of fish and invertebrate populations that feed birds, and yes, humans.

The inescapable thought of doom does not prevail as we tuck our concerns in the background. This is our first time here. It might be our last time to visit the wonderland unfolding in front of us, and we should take advantage of visiting the Dry Tortugas.

Brown Noddys, numbering about 2,000 and the uncountable Sooty Terns on nearby Bush Key seem in continual nervousness, suddenly wheeling above the colonies far beyond the large sign telling us humans to keep out.  Hundreds or more are in the air, flying helter-skelter before settling down and out of sight.  Occasionally, multitudes of terns fly only in one direction.  Are they moving as a flock toward a foraging site?  Many times, the flocks reverse direction and wheel back to the colony.  A Peregrine Falcon perching in a dead snag in the middle of the foray could be the reason for the movements of the terns, but if so, the reason for the tern’s flight directions is not readily apparent.

Hundreds of Brown Noddys are sitting on rotting pilings of a coaling station left from bygone years.  A few trees and bushes dot the humid landscape.  Campers occupy the eight available sites in a partially treed corner on the southern end of Garden Key.  The campers look happy to see our group and a couple of them volunteer useful information such as showing us a Chuck-wills-widow that is sleeping ten feet from a tent. The nightjar is one of many migrants expected to visit the Dry Tortugas.   We cross a wooden bridge over the moat and through an opening of the thick brick walls of the fort. Inside is a large open expanse in the shadow of the red arched walls and a solid black lighthouse towering above one of the sides of the bulwark.  This is the old military parade grounds, which for a split second brings memories of a parade ground once marched on in San Diego some 50 years ago and remembrance, again, of that job offer with the Pacific Program. Few park visitors enter the parade grounds, being content to climb the steps to the top of the fort’s walls or stroll parts of the outside perimeter. At least today, only birders are parading the grounds. A wide-bladed grass, button wood, smooth red-barked gumbo-limbo and sea-grape trees cover Fort Jefferson’s 10-acre parade ground. This is where we look for migrants.  The only source for fresh water is a dripping bird bath set up by the park.  Some migrants today may perish from a hungry Great Egret standing guard duty over the small pool of water collected below the drip. Vulnerable warblers stay clear of the water until Linda walks toward the egret, which reluctantly retreats by foot to near one of the park benches with the rest of the bird watchers.

The parade grounds                         Fresh water guarded by Great Egret

Several species of birds are foraging, including eight species of warblers, Scarlet Tanager, Wood Thrush and several Gray-cheeked Thrush produce a fascinating array of migrants. The identification of the Gray-cheeked Thrush is most likely correct, but I wonder. Field characters of Gray-cheeked Thrush overlap with that of Bicknell’s Thrush, a species that possibly also migrates through Florida. Many birders consider separating the two thrushes, when they are silent, as impossible.

Not long before sunset, several members of the tour take a walk around Fort Jefferson. Although often described as a hexagon, the 8-foot thick walls of the fort stand about 50 feet above the moat. The walls vary in length and in color since the bricks are from two localities. Our route is along the 70-foot wide moat where tropical fish and other warm water animals entertain as we skirt the clear waters. Surveys indicate trouble for fish within the park. I wonder how much that is related to the troubling mortality of surrounding reef coral A crocodile sits on some broken rocks below the brick fort. Amid our guides informed stories of history and wildlife, Spotted Sandpipers and a Belted Kingfisher keep us alert as we look for fanciful fish and tropical invertebrates before completing the 1.2-mile trail.

Crocodile in the moat.                                           Brick work damage

Back aboard Spree, everyone joins to compile a checklist for the day and enjoy dinner. Air conditioning keeps us comfortable during the night.

26 April 2015

A familiar Eurasian Dove, a species that in just a few years’ ranges over most of the US, perches on a metal grill provided in the campground. The National Park Service attempts to control invasive species, but our dove roams freely. Because of a long history of human occupation, 65% of the 81 species of plants are exotics. Removing exotic plants is usually a good thing. However, after invasive Australian pines that attracted migrating birds to Loggerhead Key were removed, far fewer migrant birds occur on the island. In Oregon and elsewhere, Himalayan blackberry is admittedly a scourge to natural habit and attempts to remove it benefit most everything in nature as nothing is able to grow in a blackberry thicket. However, Himalayan blackberry is also important for foraging and not just to humans picking the berries. In summer, berries stain Black-headed Grosbeaks beaks. Several species also use the thickets for shelter including California Quail, Spotted Towhee, Wrentits and others. Nonetheless, we are grateful that Himalayan blackberries are not growing here.

A pair of Shiny Cowbirds poses to cameras during the early coolness of the parade grounds. The starry white blossoms of night-blooming cereus exploded last night. The petals of this cactus will soon hide as light and temperature close the blooms. Although an invasive plant, the park allows it to stand since it is culturally significant to the history of the fort. Inside the parade grounds buttonwood trees and palms. An exceptionally large gumbo-limbo grows near the part of the fort now residences of park staff. Gumbo-limbo is a native, but a human long ago planted it inside the walls of the fort.

In a few hours, three new species of warblers, Veery and an unidentified hummingbird keep everyone alert.  Gumbo-limbo, a semi-evergreen produces blossoms and fruit that attract wildlife. The tree we scan today is larger and it has more leaves than the gumbo-limbo Linda and I observed at Flamingo a week ago. Apparently, time and lower latitude explain the advanced growth. We are not sure why birds are now foraging in the parade ground tree, but it could be blossoms that lure insects much like blooming madrone attract northbound warblers in southwestern Oregon. Just how many insects are available to migrants in the Dry Tortugas, at least today, is not known, but it is apparently far more than our guides suggests. One-source reports a total of 410 species of insects have been found in the Tortugas, but I wonder if that number is from several years of research. Famed ecologist E. O. Wilson discovered insect fauna on Dry Tortugas to vary from year to year since periodic hurricanes wiped out insect populations and their diversity. With periodic clean slates, the islands might be death traps to hungry migrants. That might explain the dead Barn Swallows the group found yesterday. Our guides told us that insects are sparse on Dry Tortugas and that many migrants that tarry here will soon starve. What birds we see today, either will disappear by moving north or will perish. I wonder if there is now a lack of flying insects to feed swallows. Are there sufficient numbers of other insects to nourish the many warblers and other migrants our group are finding? No one is reported finding mortality of the tree foragers.  

The last direct hit to Dry Tortugas by a hurricane was Hurricane Charley in 2013. Storm surges of up to 6 feet damaged everything on the islands and the storms were deadly to most, if not all, insects. Perhaps the last two years have been long enough to produce more insects. Would more migrants go hungry when spring was only months from a ravaging hurricane? Could there exist an axiom worthy to compare to the further north you go, the fewer southern birds you see? Could it be that the harder the wind blows, the fewer insects survive?

Questioning whether my 1962 wintering Black-whiskered Vireo is countable seems moot. By now, numerous Black-whiskered Vireos have graced my lenses. Presently, Linda and I have seen 18 species of warblers at Dry Tortugas. The group list includes 23 species, three of which Linda and I lack and two species we found this year before coming to the islands. Although our itinerary causes Linda and me to skip finding migrant warblers on the coast of Texas, we believe our year list of Parulidae will include most species. Time will tell. In the meantime, the parade grounds afford life warblers for Linda including Magnolia and Bay-breasted Warblers.

Falcons are taking advantage of the migrants.  I am not sure what species a Kestrel is after, but a Merlin spent over two minutes chasing the same Barn Swallow.  The falcon made several steep dives, each between about 45 and 65 degrees, and every time, the swallow out maneuvers the falcon.  The Merlin ends the chase when it perches in a courtyard buttonwood and the swallow continues flying for insects.

The weather becomes brutal, at least to Linda, I, and most of the tour.  Our guides complain that it is too hot and humid to enjoy looking for birds all day.  However, it is not too hot or humid for a distant rare Black Noddy that someone thankfully spots on a bush next to Brown Noddies. The proximity of the two terns makes the identification relatively easy.  Later in the day, presumably the same bird is visible from the deck of the docked Spree.  By then, everyone is able to brag that they have seen a Black Noddy. 

The day is broken by a cruise past Hospital Key to see Masked Boobies and to search for a subadult Red-footed Booby reported a few days earlier.  The Red-footed Booby is either gone or we overlook it. Many birders appear disappointed in missing the prized booby, but everyone is grateful for the cool air set in motion by the Spree cruising the smooth water.

Masked Boobies                                            Campground

Later in the day and back on Garden Key a small group of die-hard birders forage the parade grounds. Linda and are among them. Martin Meyers from Nevada locates a Townsend’s Warbler, which Linda and I easily verify.  The bird is photographed by at least a dozen of the party sporting big lenses.  One of photographers is Isaac Sanchez, who photographed a record 603 species of ABA species last year. 

27 April 2015

It is not just the humidity. It is also the heat that is wearing everyone down. However, most of the tour group is up early for the last tour of Garden Key.  Isaac finds a Wilson’s Plover near the campground and I locate a Dickcissel for the group. It is inside the walls of the fort near the hum of air conditioners cooling park residences.  Dave Goodwin, one of the guides, and I tread some of the taller grass where he believe a Short-eared Owl might be hiding. No owls are found. We then check all the tree limbs for roosting Antillean Nighthawks.  A camper said he heard the tropical nighthawk yesterday morning.  Dave and I fish and find neither fowl.  Later, I locate a Yellow-crowned Night Heron.  

Around 9:30 am, we are onboard and motoring south to the Gulf Stream.  Fort Jefferson and the milling terns garner a last wistful look before the Spree heads east toward Key West. The route may reveal more pelagic species than found earlier.  Possibilities for a new ABA species might be out there. For example, Band-rumped Storm-Petrel may to occur somewhat regularly along our route, but not today. Pomarine Jeager is a new year bird. It is one of the two that fly close enough to reveal all of its secrets. Their field marks cement an easy identification.  Linda is on the observation deck for good looks of Bridled Tern and Audubon’s Shearwater.  At least one subadult Northern Gannet comes into view, as do more Audubon’s Shearwaters and Brown Boobies.  The temperature continues to climb, with little relief from the partially cloudy sky.  Eventually, Harris Abramson, a birder from Cincinnati, and I are the only hands on deck.  That is, the observation deck. The remaining birders are wilting on the middle deck or inside basking in the air conditioning. It is becoming a struggle, but Harris and I keep hydrated, cooled ever slightly from the forward motion of the boat and entertained by shearwaters and the prospect of something different. 

It is late afternoon when we dock at the marina on Stock Island.  It is a relief that our RV batteries are charged enough start the electric generator to run our air conditioner. Linda and I are grateful that we can spend a night at home rather than onboard as the others do.  We are happy for experiencing Dry Tortugas, with its tropical clime, its pelagic setting, its history and its beauty. We happy from adding several birds to our life lists, with terns and boobies, a shearwater and warblers, rounding our birding to a new high.   

28 April 2015

The alarm wakes me at 5 am for time to be ready for a tour of the lower keys. Linda decides to forgo the tour and I tell her that if a reported Bahama Mockingbird is around, I will personally be her guide.   I get a ride at 6 am with the couple that earlier shared the berthing place on board the Spree.  We caravan to Sugar Loaf Key and drive to a dead-end road, cross a bridge to Saddlebunch Key and onto a trail in Key Deer National Wildlife Refuge.  The target bird is Mangrove Cuckoo, a species I have seen only once in 1962.  The trail passes through dense mangroves and almost as dense flocks of salt-water mosquitos, all of which attempt to perch on my bare elbows.  Despite published suggestions not to use playback, our tour leader asks people to play Mangrove Cuckoo vocalizations.  Eventually, it is hard to separate playback from a possible bird, especially once our guide turned up the volume.

We soon reverse our direction and the party of cuckoo hunters saunters down the paved road that brought us here.  Tall and thick groves of mangroves tower at the sides of the road and a bird or two flies from one side of the road to the other.  However, they are all red cardinals. After about 30 or more minutes of loud grating playbacks, a different bird flies over the road.  It is not a cardinal.  This time the bird has a long tail. The bird is not red and has a breast close in color to ochre. I see a grayish back as the bird quickly dives out of sight.  Christopher, the guy who hit his head in the shower so badly yesterday and whom Linda suspects may have had a mild concussion, also shares the same view of the flying bird.  He and I likewise hear it call, albeit very briefly.  I ask him if he feels all right today and he answers in his normal optimistic jovialness that he feels fine and certainly well enough to know a Mangrove Cuckoo when he sees and hears one. A few minutes after the cuckoo flew over the rest of birders, we dive back into our vehicles. Christopher and I may be the only ones with smiles.

                    Hunting Mangrove Cuckoo (upper left), Key West Tropical     Forest (lower left) and a pair of Jungle Fowel, with chicks (right) 

We drive back to Stock Island and enter Key West Tropical Forest and Botanical Garden where our ABA finding guide states there is no fee and to ignore requests for donations.  That statement was published 10 years ago and today we all pony-up to the required $5 entrance fee.  François Grenon from Quebec and a member of our group, found a Bahama Mockingbird in the gardens on 24 April.  Since then, many birders have seen the mockingbird.  The bird occurs every day but one day since the 24th.  Today, the rare mockingbird is again absent and either it moved to a nearby location or left the region altogether.  

White-crowned Pigeon might be a consolation prize for some. I saw the species in the 60s and seeing one today might seem like seeing a new life bird.  While lamenting the loss of the mockingbird or a twenty-first century gander at a White-crowned Pigeon, someone announces that an Antillean Nighthawk is roosting in a tree near one of the buildings.  I rush to the spot.  A large nightjar, nothing similar to any nighthawk I have ever had the pleasure, is sitting on a bare limb in plain sight of now perhaps 30 birders.  It sleepily blinks as camera shutters open. At last, I get my Antillean Nighthawk.  It is ABA 711.   

Following a lunch at a Cuban establishment in old Key West, the caravan drives to a site called the Indigenous Park.  Much of the property serves for rehabilitation of birds.  However, outside the cages are several Jungle Fowl, including two males.  One of the males is with a female and half-a-dozen fuzzy chicks.  The markings remind me of wild galliformes.  Jungle Fowl are not countable in ABA land, but I think I will put them down in my escrow list. 

The temperature and humidity continue to challenge everyone as I join the tour group sitting in a small shady spot on the porch of main building of the Indigenous Park. I enjoy the relative comfort, which still is producing rivulets of sweat running down my face. Perhaps I can ignore the heat and let my mind wander. Did anyone in our group see Great White Herons? Just to the north is Great White Heron National Wildlife Refuge and these giants of North American herons are reportedly more abundant in the keys than in Everglades National Park. I saw my first Great White Heron with Sandy Sprunt, the same day a Zenaida Dove sits in a tree outside Sandy’s home. Later, also in December 1962, I saw two other Great Whites in the lower keys, including one during a Christmas Count.

Thoughts of the taxonomic status of Great White Heron entered my mind. Is it a color morph or subspecies of the Great Blue? What is the taxonomic status of the Great White Heron? I had especially wondered about these birds when preparing files on the taxonomy of birds in Oregon. During my museum days, I was well aware that the AOU had decided that Great White Herons are conspecific with Great Blue Heron. In order for me to write anything about the subspecies of Great Blues in Oregon, or any other place for that matter, I needed to believe that those white birds were actually subspecies or not. At the time, over a decade ago, I was not convinced.

After retirement, I ran into an important and largely ignored work published by the Florida Fish and Wildlife. Like so many, I chose to ignore the report and follow the status quo, that the Great White Heron is nothing but a subspecies of the Great Blue Heron. The report, which I had copied into my computer, is by Heather McGuire. It was printed in what many people call the gray literature. McGuire concluded that where white and birds overlap, white birds mate with white birds and blue birds mate with blue birds. That is not random mating, something one expects between conspecifics. What is going on out there in the mangroves is what we call assortative mating, something discerning species practice. That means that the Great White Heron (aka Ardea occidentalis) is a good biological species. Furthermore, McGuire investigated the genetics of these herons and found differences. Will the differences and her other data be profound enough to convince check-list committee members of the AOU to deem the rank of species to the white herons? That would be great. In the meantime, someone will have to submit a proposal to the committee recommending that the white herons be once again full species.

As it turns out, the only Great White Heron recently in my sights is the one a few days ago at Flamingo. Perhaps our trip down the keys was too hasty. I would like to have seen another individual to check it and myself about the physical impressions I had of the Flamingo heron. I thought that bird was large. Great White Herons are often reported as larger than Great Blue Herons, especially by having a longer and thicker bill. Although the Flamingo Great White Heron was large, my late friend Robert Dickerman once told me that there is a great amount of individual variation between Great Blue. Because of the reluctance of museums to pack and ship these large and gangly specimens, Bob spent years visiting museum and measuring breeding specimens of the herons. His criteria for a bird on its breeding grounds meant an individual heron had to have gonads to prove what they were doing, which was actually breeding. In choosing his specimens, Bob was avoiding inclusion of any wandering birds that were not from the breeding site. Yes, nonbreeding birds may wander away from where they might normally breed.

Bob’s data reveals considerable variation in bill length. Samples of blue herons from mainland Florida, Texas, the Gulf Coast of Mexico and white birds from Florida have similar average bill lengths. There also is considerable variation and overlap in-depth of bill between the two species of herons, but bill depth definitely is greater in the white species. Usually, the bill of most Great White Herons appears large, and appears like the bird I witnessed a few days ago. Although measurements made by different ornithologists are not always directly comparable, published data from Bob and McGuire are not that dissimilar. To the herons, size, at least of some of their parts, may not matter. However, white birds have much shorter occipital plumes and the color of skin around the face may be something they use to separate themselves, other than the obvious differences in coloration of plumage, legs and bill. The situation is intriguing and invites further investigations, especially the business of assortative mating. Perhaps the two styles of herons know something the rest of us are ignoring Maybe I will try to rustle up a proposal recommending the AOU to re-split Great White Heron from Great Blue Heron.

It is getting hotter and the herons have filled in the gaps of near boredom from meager birding. My mind returns to going home to the RV. Around 2:30, my transportation hosts deliver me back to the RV.  By now, it is extremely hot and, at the boat dock parking spot, the air is dripping humidity.  I open the back door and discover Linda drenched in sweat.  The air conditioner had blown a circuit breaker and the inside the RV is a steamy oven.  It is dangerously hot.  I am not sure why the air conditioner stopped, but the likely possibility is an electrical overload. Removal of the panel covering the circuit breakers tells the story, and I quickly reset the circuit breaker and restart the generator. Our cooling system works, although marginally. What if the problem of the air conditioner would have been more than simply resetting the fuse? It would have been difficult to cool our home from the cab air conditioner. Despite the fact that the air conditioner begins cranking out cool air, the deplorable situation is enough for us to realize we should not stay another day in the keys and leave. We depart the torrid Florida Keys for another time, hopefully earlier on the colander when the tropics might not be so tropical. Should we return to Dry Tortugas National Park, we would also make our revisit by day trips. Even a couple or more should be less than an organized tour. 

Driving to Homestead, I still visualize Linda sweltering in the dangerously heated RV.  In about three hours, we reach the mainland where it actually feels comparatively cool and less humid than Key West. We spend one more night in Homestead before setting our compass for more temperate climes.

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