Thrushes Return to St. George

This past week on St. George Island has been highlighted by an influx of Catharus thrushes. They have been most conspicuous in the shady corners of the island, where they hop along grassy borders and flick through leaf litter.

The Catharus thrushes that are regularly occurring Nearctic-Neotropical migrants on the Gulf Coast (Swainson's, Gray-cheeked, and Veery) are of particular interest to our research. Delaware State University Master's student Mariamar Gutierrez-Ramirez is studying the stopover refueling performance of these species on the island after trans-Gulf migration. Analysis of residual plasma triglyceride levels will indicate whether the birds are refueling on the island. To do this, a small sample of blood is quickly taken from all thrushes that are captured in our mist-nets. Birds are then banded, measured, and released unharmed.

Catharus thrushes have been particularly photogenic along our transects this past week. If you stand still they will often come within just a few meters, intent upon their foraging efforts. See if you can pick out the subtle differences in their plumage.

It won't be long until they return to their northern breeding grounds, where their distinctive, flute-like songs are unparalleled in beauty.

Veery (Catharus fuscescens)

Swainson's Thrush (Catharus ustulatus)

Gray-cheeked Thrush (Catharus minimus)

The Sun Brings Snakes

Calm winds and sunny skies have returned to St. George Island after a period of stormy, unsettled weather. Although many of the birds that were grounded during the past week have left the island, we are still capturing above average numbers of birds.

With the sun comes increased sightings of the cold-blooded residents of the island. Yesterday and today have featured several snake at our field site. This afternoon, our net lanes were the perfect sun bathing location for a cottonmouth (Agkistrodon piscivorus).

An Unexpected Guest

Sure, mist-nets are designed to catch small birds. That doesn't mean larger birds can't find their way into them, though!

As Mariamar did a net check this afternoon, she came across an unexpected bird. A Green Heron! With some careful maneuvering, we were able to extract the heron and admire it briefly before releasing it. We made sure to keep its deceptively long neck under control, so that it didn't turn our eyeballs into an afternoon snack.

Green Herons are ambush predators, relying on stealth and camouflage to strike down their prey. They are Neotropical migrants, with the majority of North American breeders spending the winter in the tropics. Whether this is a local or a recently arrived trans-Gulf migrant, no one knows.

Lori poses with the heron, a nice change of pace to our never-ending line of songbirds. 

This freshwater wetland in Unit 4 ANERR is home to Green Herons in the breeding season, and backs up to the net where the bird was caught today. 

St George Island Fallout!

April 15th brought an unusually strong cold front barreling through the Florida Panhandle and northern Gulf of Mexico. Strong winds and heavy rains pounded St. George Island for the first half of the day, before finally clearing to a brisk north wind.

These conditions served as a rude arrival for songbirds crossing the Gulf the following night. The sun rose on the 16th to reveal St. George Island covered in recently arrived trans-Gulf migrants, taking advantage of the first bit of land they could rest on. Flocks of buntings flushed off the grassy shoulders, kites and swallows wheeled through the gusty skies, and streams of electric-colored grosbeaks, tanagers, and orioles crossed from tree to tree.

Over the following day and half, we were able to band roughly 150 migrants at our field site in Unit 4 ANERR, and observed 51 species of trans-Gulf migrants, many in astounding numbers.

We were also very excited to have ECSC colleagues visit from Florida A&M University on the 16th, including Dr. Charles Jagoe, Dr. Daniel Osborne, and Ph.D students Mario Marquez and LaTrisha Allen.

Here are some photos that help sum up what was an amazing few days.

As the front cleared on April 15th, the winds intensified and shifted to the northwest, turning Apalachicola Bay into a roiling cauldron. These are very poor flying conditions for a northbound migrant, and for the next few days St. George Island became a haven for these weary, tropical travelers.  

The Swainson's Warbler is an elusive summer denizen of southern forests with dense understory, whether its rhododendron thickets in the Appalachians or canebrakes on the coastal plain. 

The Prothonotary Warbler spends the breeding season in mature, flooded forests of the south. Their name refers to the Chief Secretary of the Chancery at Rome, who wears a yellow robe. It is also nicknamed the Golden Swamp Warbler, and is, without a doubt, one of the brightest of all songbirds. 

We were lucky enough to band a few Painted Buntings, including this adult male.  Wintering in Central America, these jewels breed in two distinct populations, one on the Gulf Coast and one on the south Atlantic coast.

With a massive, powerful beak, we had to guard our fingers from this male  Rose-breasted Grosbeak.

The Blue Grosbeak is another species with a formidable beak, and is a wide-ranging breeding species in open areas throughout the southern tier of the country. 

Not all is peaceful for the migrants on St. George Island! They must remain forever vigilant against predators, including this Merlin. Merlin's are the medium-sized falcon of North America, smaller than the Peregrine but larger than the kestrel. They maraud along the coastlines during the winter, before retreating to the far north to breed.

Dr. Lori Lester (left) demonstrates the process of handling a Rose-breasted Grosbeak to Dr. Charles Jagoe, Dr. Daniel Osborne, and Ph.D student LaTrisha Allen from Florida A&M University. 

The 2014 Season Begins On St. George Island

Today, April 14th, marked our first full day of field work for our Delaware State University crew on St. George Island, Florida this spring. Like last year, we will be operating mist-nets at Unit 4 of the Apalachicola National Estuarine Research Reserve (ANERR) as part of a research effort to evaluate the significance of St. George Island as a stopover site for trans-Gulf Neotropical migrant songbirds.

Using mist-nets allows us to inspect the physical condition of recently arrived birds and better assess their age and sex. While having a bird in hand, we give it a uniquely numbered leg band which will be its calling card if it is ever caught again.

We were excited to hit the ground running, and had a productive morning, joined by Megan Lamb, the ECSC coordinator for ANERR.

Our first bonafide neotropical migrant was this Worm-eating Warbler, a species that winters in Central America and the West Indies. At home in the mid-story of forests, they specialize in probing for morsels in dead leaf clusters. 

Mid-morning we had a noticeable influx of newly arrived trans-Gulf migrants at our field site.  The standouts were two absolutely vivid  male Scarlet Tanagers, perhaps seeing ground for the first time since South America. 

There are more than just songbirds around! This dashing Short-billed Dowitcher was foraging actively in the shallow bayside waters of Unit 4. Before long, this bird will migrate northward to the boreal muskegs for the breeding season. 

Although our research focuses on long-distance migrants, we can't help but admire the beautiful year-round residents of St. George Island. This male Eastern Towhee offered a rare unobstructed view as we scouted our field site out yesterday afternoon. Note the white eye. Towhees in northern states have red eyes. 

We were excited to recapture one of the resident White-eyed Vireos that we banded last year.  White-eyed Vireos are common breeders in the dense evergreen understory of the pine flatwoods on St. George Island.