The Local Sights

The view coming off the bridge into Apalachicola.

A rusted trawler rests in the marshes of the Apalachicola River delta.

Storms roll in over Apalachicola Bay as we cross the bridge onto St. George Island. When a trans-Gulf migrant approaches the coast and encounters stormy weather, they often take aim on the first land they see. Here, that first bit of land is St. George Island.

The view along Gulf Beach Drive, St. George Island. The open areas are utilized by migrant Bobolinks, as well as a host of adaptable residents such as Gray Kingbirds, Northern Mockingbirds, and Common Ground-Doves.

Beyond the rows of beach houses lie remnant tracts of pine flatwoods. It is in these woods that migrating birds congregate. This pond is in the middle of our plot in Unit 4 of the Apalachicola National Estuarine Research Reserve (ANERR). Local Green Herons are often seen along the perimeter, and at dusk begins a ringing chorus of frogs and toads.

The sun sets over Apalachicola Bay and the Bryant Patton Bridge. Numerous migrant shorebirds feed along the bay shore, while terns from nearby breeding colonies hunt overhead. The bay is also a hotbed for oyster harvesting, helping make Apalachicola one of the oyster capitals of the country.

Vireos: It's All In The Eyes

Vireos are a New World family of birds that are characterized by their deliberate feeding methods and hooked bills. Two of the most likely vireo species to be encountered on St. George Island are the White-eyed Vireo (Vireo griseus) and Red-eyed Vireo (Vireo olivaceus).

As you might expect, the eye color is a good clue for identifying these birds. The eye is also a clue for the bird's age, as neither species gains their namesake color until they are nearly a year old.

The Red-eyed Vireo, seen below, is found in almost any sizable patch of broadleaf forest in eastern North America. It's sweet, monotonous "here i am, where are you" song is given throughout the day from high in the canopy, even on the hottest summer afternoons. They winter predominately in South America. Over the past few days we have begun to catch migrating Red-eyes on St. George Island, as well as pick them up on our transects.

The White-eyed Vireo, seen below, breeds at our study site on St. George Island. Throughout their breeding range in the Southeast, they prefer dense, impenetrable thickets. Often the only clue to their presence is their explosive, unmistakable song, "chick, poweeo, chick." We have banded several of the locals, as well as possibly a few migrants returning from Central America.

Boiled Peanuts

 

A dog rests while his owner stops for boiled peanuts in Eastpoint, Florida. We tried a round of cajun boiled peanuts ourselves - the jury is still out.

An Influx of Thrushes

Thrushes of the genus Catharus range throughout the Americas. The genus is characterized by generally cryptic plumage, which they make up for with their ethereal, fluted songs. Crepuscular denizens of the undergrowth, thrushes often go unseen to the casual observer.

Their annual migrations cover up to 6,500 km, traversing between their breeding grounds in North America and their wintering grounds in Central and South America.

As Spring trans-Gulf migrants, thrushes are dependent on finding stopover sites that provide shelter and refueling opportunities as they return to their breeding grounds. Quality stopover sites along the Gulf Coast are of particular importance to three Catharus species: Veery (Catharus fuscescens), Gray-cheeked Thrush (Catharus minimus), and Swainson's Thrush (Catharus ustulatus).

We are in the midst of the peak migration period for these birds here on St. George Island. Over the past few days we have captured our first individuals of each species. Learning to identify these thrushes takes practice, but with care there are certain unique characteristics you can clue in on.

The Veery's preferred breeding habitat is broad-leaf forest, and is best identified by its uniformly reddish coloration.

The Swainson's Thrush is found from coast to coast in North America and shows off distinctive buffy spectacles and upper breast.

The Gray-cheeked Thrush breeds in the boreal forests of Canada and is best identified by its cold, gray coloration and lack of an eye ring.

Brilliance

Birds capture our imagination because they can fly, they can sing, and because they are beautiful. Some birds in particular are capable of reawakening our childlike enthusiasm, leaving us speechless and in awe.

One of these moments happened today, when we were treated with one of the most spectacular of all North American birds, a Scarlet Tanager (Piranga olivacea). Although we had detected this species multiple times on transects through our study site, we had not captured one. Finally, our dreams came true.

This particular bird is a second-year male. If you look closely, you can see the molt-limit on his wing, where the more worn, dull gray primary coverts contrast with the fresher, velvety black of the greater, median, and lesser coverts. Wintering primarily in South America, in summer the Scarlet Tanager brings its tropical brilliance to broadleaf forests across eastern North America. 

Closer inspection revealed that he had burned all of his fat reserves and had begun to catabolize his breast muscle. In order to continue his journey northward and successfully breed, he will have to regain much of what he has lost. Whether he does that here on St. George Island is one of the questions we are here to answer.

An Unexpected Vistor: The Giant Palm Weevil

Occasionally our mist-nets capture unintended visitors. Over the past week we have caught two impressive Giant Palm Weevils (Rhynchophorus cruentatus), which thankfully stayed put long enough for a quick photograph.

These native weevils are restricted to the southeastern United States and are among the largest weevils in the world. Their native host is the Cabbage Palm (Sabal palmetto), which is abundant at our field site. As you can see in these two individuals, Giant Palm Weevils come in a variety of black and red color patterns. 

The similar Red Palm Weevil (Rhynchophorus ferrugineus), native to the Old World, is rapidly colonizing the globe and is considered a serious pest to a variety of palm species. Likely traveling with imported palms, this species has recently arrived in the Caribbean and seems poised for an invasion of the Americas. 

Larvae of the genus Rhynchophorus are considered a delicacy in Asia. They are said to taste creamy when raw, and like bacon when cooked.

Migrant Warblers

Boreal migrants such as the Blackpoll Warbler and Magnolia Warbler are under increasing pressure throughout their ranges. One of the principal goals of our work in Apalachicola is to find out how important the barrier islands are as en route stopover sites for these species. 

Blackpoll Warblers perform one of the most impressive migrations of all North American birds. Weighing just 12 grams, they breed in the boreal forests of Canada and spend the rest of the year in the rainforest of South America.

To fuel this journey, they must first double their body weight in fat stores. They then take off on a non-stop flight that will take them over 1,000 miles, crossing over vast sections of ocean. Like most migrating songbirds, they migrate at night, using celestial cues to orient themselves.

 The Magnolia Warbler has very specific habitat requirements during the breeding season, depending on young stands of conifers. During the winter, it is found in a variety of habitats in the West Indies and Central America. Very active and colorful, the Magnolia is one of the crown jewels of the wood-warbler family.

These two birds are both adult males that we have caught in the past week on St. George Island. Males arrive first in the Spring, so that they can establish their breeding territories before the arrival of the females.

Island Snakes

The barrier islands south of Apalachicola have their fair share of snakes, including four venomous species. Over the past week, we have seen a variety of species at our field site on St. George Island, ranging from small garter snakes to black racers and black rat snakes.

During the heat of the afternoon, many snakes can be found sunning themselves on the gravel back roads. A couple of days ago we spotted this water moccasin (Agkistrodon piscivorus). Also know at the cottonmouth, this semi-aquatic viper is relatively common in swampy country of the Southeast. When threatened, a moccasin flattens its short, fat body and opens its mouth, revealing the bright white lining.

Venomous snakes often get the short end of the stick, so we decided to give this one a free pass. With a long stick, we picked it up and moved it off the road.

Mist-nets and a molt-limit

One of the main components of our field research on St. George Island is mist-netting. These nets are designed to passively capture birds that are passing through an area, which we then extract, band, and examine in hand. The aluminum band is placed on the bird's leg and has a unique number on it which serves as a sort of social security number. Studying birds in the hand allows us to better age and sex the bird, as well as check their physical condition.

Below is a photograph of one of our net lanes on St. George Island.  If you look closely you can see a line of nets set up in the open path. We have ten nets set up, varying in length from 6 meters to 12 meters. The nets are designed to be invisible to birds.

Monitoring the nets every 10 minutes, we extract any birds and bring them back to our banding station, which is a portable table surrounded by lounge chairs. It typically takes us two to three minutes to process the bird before it is released back into the wild.

Below is a photograph of a male Summer Tanager that we caught on April 22nd. An adult male Summer Tanager is all red, but if you look carefully you will see that the flight feathers of this bird are still green. This tells us that it is a second-year bird, which means it was born last summer. The green feathers are retained juvenal feathers that the bird had when it first fledged. This contrast between old and new feathers is called a molt-limit, and is one of the vital clues we can look at to help age a bird.

Summer Tanagers are neotropical migrants that breed throughout the southern United States. They winter in forested areas of Central America, and on their Spring flight northward cross over the Gulf of Mexico. Close examination of this bird told us that it had burned most of its energy reserves during its crossing.

First Day Fallout!

Our research team from Delaware State University arrived in Apalachicola, Florida on April 19th. To the average person, the weather was rotten, with howling winds and intermittent downpours. To bird researchers like us, however, the weather was perfect.

After dropping off our gear at the trailer we'd be staying in, we took the car and crossed the bridge onto St. George Island to check out our field sites. As we scanned the pine forests and suburban streets, we could immediately tell that birds were everywhere. Mixed-species flocks of warblers, vireos, tanagers, orioles and grosbeaks were streaming through the island, filling peoples front yards and the surrounding shrubs.

What was going on??

During Spring migration, many songbirds that have wintered in the tropics must cross the Gulf of Mexico to return to their summer breeding grounds. Being a Gulf Coast barrier island, St. George is positioned as one of the first safe havens for these arriving trans-Gulf migranst.

The island experiences the highest volume of migrants when southwest winds push them east of their principal flight paths further to the west. If these conditions are followed by strong north winds (a head wind), then many of the recently arrived birds will be forced to stay on the island, creating a bird fanatic's dream: a fallout. As luck would have it, today was one of those days.

As we explored the island, we tallied over 90 species of birds, including 20 species of warbler. We saw birds in outlandish places: Dickcissels in pine trees, Gray-cheeked Thrushes on the roadside. We saw dozens upon dozens of Black-throated Green, Hooded, and Yellow Warblers, while flocks of Indigo Buntings rained down from the sky. Scrub oaks were packed with glimmering birds of all sorts, foraging feverishly on the arthropods that they could find. All the while, we could hear the soft chip notes of arriving migrants high the sky, slowly getting closer.

As dusk descended we reluctantly pulled ourselves away and drove the short commute back to Apalachicola. Arriving at our trailer, we feverishly ate some food and got ready for bed. Like the birds we had just observed, we too had traveled over 1,000 miles and were tired. Tired and excited about our next three weeks of work.