A NEW FRONTIER: PELAGIC BIRDING IN THE GULF OF MEXICO
By: Dwight E. Peake and Mark Elwonger
Originally published in ABA "Winging It" Volume 8, Number 1; January 1996.
Reprinted with permission from the authors and the ABA
Forward: This landmark paper by Dwight Peake and Mark Elwonger
was published at a time when pelagic birding in Offshore Texas was still in it's infancy. These men and several
others mentioned in their paper are due a great deal of credit for bringing Pelagic Birding to Texas throughout the 1990's.
I have catalogued their efforts in the Trip Archives found on this website.
With each subsequent trip over the years since they started organizing Texas Pelagic Birding trips in 1994,
we have learned more about the occurance and distribution of birds and marine animals found
in the offshore waters. There is undoubtedly much more to be learned. Garett Hodne
Introduction
Although pelagic birding off the East and West Coasts of North America is well established, it is just beginning in the
Gulf of Mexico. Early attempts at offshore birding ended with frustration and a feeling that birding in the Gulf was not
productive. An increasing knowledge among birders of seafloor geography and water hydrology, as well as the results of
recent offshore research, is changing opinions regarding pelagic birds and birding in this region.
History of Gulf of Mexico birding
Most birders are familiar with the nearshore birds of the Gulf of Mexico: a substantial percentage of the US population
of several species (Neotropic Cormorant; Laughing Gull; Forster's, Gull-billed, Sandwich, Least, Royal, and Caspian Terns;
and Black Skimmer, for example) nests here, and many others migrate through or winter on the coast. Other than the birds
of the Dry Tortugas, however, most birders are probably unaware of the regular, true pelagic seabirds present throughout
the northern Gulf (pelagic is defined as waters deeper than 180 meters). For example, the 1984 edition of A Birder's Guide
to the Texas Coast lists only four species of pelagic birds—Masked Booby, Pomarine and Parasitic Jaegers, and Sooty
Tern—and each in the "how lucky can you get" category. Even as recently as 1993, the revised version added only
Northern Gannet and Magnificent Frigatebird to the list of regularly occurring species, and noted that "much more needs
to be learned about pelagic birds off the Texas coast." Shearwaters and storm-petrels are still relegated to a list of
"possible" species.
As early as the 1820s, evidence existed for the Gulf's birding potential. John James Audubon's painting of Audubon's
Shearwater, for instance, is based on birds he saw and collected in the Gulf of Mexico. Most pelagic bird records
consisted of dead or dying birds washed or blown ashore during storms until the late 1970s, when C. D. Duncan and
R. W. Harvard did pioneering ship-based work off Alabama, and T. H. Fritts and others did aerial surveys off Florida,
Louisiana, and Texas. Duncan and Harvard managed to show that Masked Booby, Bridled Tern, and jaegers—species
previously considered rare—are regular and fairly common. The offshore geography of Alabama, however, made trips
to the deeper waters usually needed for finding many other species difficult and, except for an occasional trip
reported in American Birds, the interest generated by Duncan and Harvard subsided. In Louisiana, there were probably
less than five organized offshore birding trips taken between 1980 and 1994. In Texas, birders took many trips over
the continental shelf (but not beyond) and recorded a few pelagic species, but the results were inconsistent and
often proved disappointing.
In 1991 Texas birder Ronnie Carroll took trips into Mexican waters just south of the US where deepwater is closer
to shore and spotted many Band-rumped Storm-Petrels and Bridled Terns. In 1992 Leach's and Band-rumped Storm-Petrels
and Bridled Terns were noted on nearshore Texas trips. In September 1992 Carroll arranged a deepwater trip which
produced a then-startling seven pelagic species, which stimulated a more widespread recognition of the potential
of Gulf pelagic trips. Trips organized by Carroll in 1993 continued to produce records of birds previously considered
very rare or accidental.
The National Marine Fisheries Service (NMFS) also began marine mammal census work in 1991 in the Gulf and recorded bird
observations. This work continued in association with Texas A&M University during the GulfCet Project, sponsored by the
Minerals Management Service, US Department of Interior, which studied the marine mammals over the Continental Slope from
Alabama to Texas. The authors organized trips to offshore Texas during 1994 and 1995, and the Louisiana Ornithological
Society sponsored two trips from Venice, Louisiana, during 1995. The results of these trips and the GulfCet Project
(which have recently been published) have established that the Gulf of Mexico is far from devoid of pelagic seabirds
and can regularly provide good birding opportunities.
Gulf of Mexico Geography, Oceanography, and Habitat
The United States, Mexico, and Cuba are the countries bordering the Gulf basin which covers an area of 1.5 million
square kilometers. The Yucatan Channel between the Yucatan Peninsula and Cuba connect the Gulf with the Caribbean Sea,
and the Straits of Florida between Florida and Cuba connect the Gulf with the Atlantic Ocean. The basin (see Figure 1)
has three distinct zones based on bottom depth: the continental shelf defined as areas with bottom depth of less than
180 meters), the continental slope defined as areas with bottom depth between 180 and 3,000 meters), and the abyssal
plain (defined as areas with bottom depth greater than 3,000 meters). Unlike most ocean basins where the continental
shelf area is proportionally small, the shelf here covers about 35.4% of the total Gulf of Mexico. The shelf is up to
240 kilometers wide off parts of the Florida, Louisiana, and Texas coasts but is as narrow as 32 km wide at the mouth
of the Mississippi River. The maximum bottom depth is about 3,700 meters. Approximately two-thirds of the land area of
the lower 48 states of the US and one-half of the land surface of Mexico drains into the Gulf.
FIGURE 1
The Gulf of Mexico has a subtropical climate and a complex pattern
of water circulation. The Loop Current—characterized
by warm, highly saline water—originates as the South Equatorial Current, which flows north along the east coasts of
northern South America, Central America, and Mexico, enters the Gulf through the Yucatan Channel, and flows out via the
Straits of Florida. It then contributes to the Gulf Stream. In summer, the current moves much farther north than in winter
and often gets within day-trip range of Venice, Louisiana. Large pieces of the Loop Current break off, spinning in a clockwise
manner and drifting west; these water masses are known as anticyclonic eddies. Smaller areas of cyclonic eddies, which bring
deep and cold water close to the surface, often form at the edges of the anticyclonic eddies. The eddies tend to dissipate
in an area at the western edge of the continental shelf along the Texas Coast which has been called the "eddy graveyard."
Areas of true upwelling, a current flowing upward due to deflection by underwater formations, are common off the West Coast
of the US but are rare in the Gulf of Mexico. A prime site for upwelling is the Florida Escarpment at the southern Florida
shelf edge, where the bottom depth drops from 300 to 3,000 meters over a distance of 17 to 35 km (10 to 20 miles), and
where the Loop Current pushes against the escarpment; this area is essentially unexplored ornithologically.
Further complicating the hydrographic situation in the Gulf is the large influx of freshwater from the Mississippi River.
The size of the freshwater plume varies and tends to be smallest in summer and largest in spring. The plume usually flows
west but in times of extreme flow—such as the floods of 1993—it may extend eastward; in 1993 the output from
the river was so tremendous that freshwater flowed out the Straits of Florida and up the East Coast! In late August, the
numbers of Black Terns concentrated over the freshwater plume can be amazing. The location of the plume is of utmost
interest to birders seeking pelagic birds, since these species seem to avoid the freshwater areas.
The complexity of the Gulf system makes for a wide variety of habitats. The coastal and nearshore areas are very rich
biologically; for example, 28% of the total US commercial fish catch is taken over the Texas and Louisiana continental
shelf. The significance of the Gulf Coast as a nesting and wintering area for many coastal seabird species has been
mentioned previously. The marine ecology of the waters beyond the continental shelf is not well-established but preliminary
information suggests that the presence of birds in a given area is influenced by these features in the Gulf of Mexico
in a manner similar to that noted by Haney off the southeast Atlantic Coast. For example, bottom depth is a factor,
since Band-rumped Storm-Petrels tend to occur in areas with bottom depth of around 1,000 meters and Wilson's tend to
occur in shallower areas. Similarly, Bridled Terns tend to occur in shallower areas than Sooty Terns. Obviously, the
birds aren't making depth measurements but are no doubt selectively feeding on creatures attracted to waters of varying
depths. Sooty Terns, Bridled Terns, and shearwaters frequently gather in areas with fish schools; an apparent association
between Whale Sharks, tuna schools, Sooty Terns, and Audubon's Shearwaters exists in the Gulf. Additionally, Sooty Terns
and Audubon's Shearwaters seem to have an affinity for bottom depth areas of about 1,200 meters. Fronts, the edges of
water masses having different characteristics, also attract various species of birds, especially at the lines of sargassum,
a brown algae, which tend to form at the fronts. Most summertime continental slope area weedlines with clumps of sargassum
over five square meters in size have Bridled Terns associated with them, and they are also prime areas in which to find phalaropes.
Pelagic Seabirds
Although bird densities in the Gulf do not compare with either Monterey Bay, California, or Cape Hatteras, North Carolina
(except in the vicinity of the Dry Tortugas), the species composition differs from those pelagic birding hotspots. The prime
pelagic birding months in the northern Gulf are April through mid-October. The Gulf's pelagic seabirds seem to exhibit three
seasons of occurrence: winter, spring, and summer; a migration period in March through early May and again in late September
through mid-November occurs but since these times lack significant investigation, the species makeup is poorly understood.
During the winter, the predominant pelagic species in the northern Gulf are Pomarine Jaeger and Laughing and Herring Gulls.
Parasitic Jaegers seem to be extremely rare and may be outnumbered 300-to-1 by Pomarines in the continental slope area, but
Duncan and Harvard found them more abundant than Pomarines over the Alabama shelf. Northern Gannets are fairly common near
the shelf edge but are rare in deeper water. Sooty Terns occur in scattered flocks. Masked Booby, Bridled Tern, and storm-petrels
are present but are rare. Manx Shearwaters may occur but certainly are very unusual in the Gulf at any time of year.
Spring is usually much more interesting than winter. Five years ago, no one would have thought that one of the most common, if
not the most common, bird over the continental slope areas during May, June, and July would turn out to be the Band-rumped
Storm-Petrel. But it is! A high count of 31 was made off Port O'Connor, Texas, on June 24, 1995, and 20 to 30 individuals
are typically seen in a day off Texas and Louisiana at this time of the year (and probably off Alabama, Florida, and Mississippi,
as well). Leach's Storm-Petrel also is present and seen regularly, but in smaller numbers. The distribution of Wilson's Storm-Petrel
in the Gulf remains a mystery. Although research trips have produced a few western Gulf records during late April and early May,
Wilson's is much less common in the western portion than around the mouth of the Mississippi, where it is a common bird during
spring and summer. Greater Shearwater is rare but probably regular during spring and it may be more common earlier in migration
during April. Audubon's Shearwaters are common but less so than in the summer. Masked Booby is uncommon in early spring but the
numbers increase later in the season. Cory's Shearwater is rare. Research trips have noted both Red-billed and White-tailed
Tropicbirds and Red-footed Boobies in spring. Although Brown Noddy nests in large numbers at the Dry Tortugas and in smaller
numbers on the Bay of Campeche in the southern Gulf, it appears to be rare in the northern part, although it has been noted
off Louisiana. Pomarine Jaegers become rare by the beginning of June, but Bridled Terns are common. Sooty Terns are less common
in spring than in summer, possibly because they are more localized to the breeding areas in Florida, Louisiana, Texas, and Mexico.
Summer has the birds noted for spring, but Band-rumped Storm-Petrel becomes uncommon by late August and rare by late September.
Leach's Storm-Petrel is usually seen in small numbers throughout September. Audubon's Shearwater becomes very common and a
recent Texas trip had at least 123 birds in one flock! Cory's Shearwater also increases in abundance and probably reaches
maximum numbers in early October. White-tailed Tropicbirds have been seen in August and early November. Masked Boobies are
common and often circle the boat, allowing excellent views. Magnificent Frigatebirds are common but are usually seen over
the continental shelf. Red-necked Phalarope is probably a regular migrant in the western Gulf, but Red Phalarope appears
to be less common; October is likely the prime month for phalaropes but much field work remains to be done to clarify
their status. Jaegers begin to arrive in August and the Pomarine numbers build to a maximum in winter. Bridled Terns
remain common at least through September but are uncommon by November. Sooty Terns are much more easily found in summer
and the frequently seen, all-black juveniles make identification easy. In the fall, summer bird species seem to gradually
diminish in numbers while the winter birds increase.
Continental Shelf Area Birding
Although this area is not as productive for pelagic species as the deeper areas off the continental shelf, the many
commercial fishing party-boats available along the Gulf Coast make such a trip as easy as signing up to go fishing,
and you may get some true pelagic birds despite the fact that these trips do not reach true pelagic waters. Such
trips have been taken in Texas since at least 1976, and the records kept by Sheriton Burr list such species as
Audubon's and Greater Shearwater, Masked and Brown Booby, and all three jaeger species; most of these have been
recorded only once or twice over the past 20 years of these trips. Cory's Shearwater, however, is an exception and
is seen on a large percentage of these trips during August, September, and October, when it is most numerous in the
Gulf. A winter trip over the shelf is very likely to produce good numbers of Northern Gannets and jaegers and might
turn up a rarity such as Black-legged Kittiwake, as well as numerous individuals of the common gull and tern species.
Migrant Landbirds
Because the Gulf is a major pathway for migration of landbirds, one can see many unexpected species far from land.
Burrowing Owls have landed on boats almost 200 miles from land. Flammulated Owl has occurred and Peregrine Falcons
are regular on oil platforms. The unsuspecting birder can easily be fooled into thinking that a rare seabird has
been spotted whena Chuck-will's-widow, a common species many miles from land during migration, approaches low over
the water. Herons, Blue-winged Teal, hummingbirds, and a variety of passerines are routinely spotted on boat trips
taken during migration.
State Boundaries
Since most interest in pelagic birding in the Gulf of Mexico may lie within the states bordering and near the Gulf,
state boundary definitions become very important for state bird listing and rare bird committee purposes. Modern
navigation technology makes precise positions for sightings simple to record, The ABA has determined that "the ABA
boundary now follows the international fisheries zones. State or provincial offshore limits follow suit." Thus, the
Economic Exclusion Zone (EEZ) limits form the ABA Area boundary in the Gulf; these extend 200 nautical miles from the
nearest US land or midway to the next jurisdiction (for example, due south of Key West, Florida, the distance is only
about 42 nautical miles, since Cuba is less than 200 nautical miles from the US). In some cases, the distance from a
given point on shore to the nearest limit of the EEZ may be greater than 200 nautical miles, because the actual nearest
land may be elsewhere (for instance, from the Alabama coast to the EEZ is over 200 nautical miles because the EEZ limits
due south of Alabama are determined by points of land outside the state). The existing state boundary definitions for
Alabama, Texas, and Louisiana do not conform to this EEZ limit and in the case of Louisiana and Texas do not conform
to existing formal fishing and territorial boundaries between these states. The boundary between Louisiana and Mississippi
is in dispute between the Records Committees of the two states; this situation provides some interesting possibilities,
such as one sitting bird simultaneously counting for two state lists!
The following proposed boundary definitions would bring the state areas into agreement with existing state and federal
territory and would provide an equitable solution to the placement of the Louisiana and Mississippi border. The southern
boundary for each of the Gulf states is the EEZ limit. Refer to Figure 2.
• For Texas: The eastern border is a line from the mouth of the Sabine River 29°41'N 93°50'W to the EEZ limit at
26°N 93°W; this line is demarcated on fishing maps and also represents the boundary of Minerals Management Service gas
and oil leasing blocks, which have different sizes for each of these two states, between Texas and Louisiana.
• For Louisiana: The western boundary is the eastern boundary noted for Texas. The eastern limit is longitude 88°45.6'W
at the official state limit ( the three nautical mile line) east of the Candeleur Islands south to the EEZ at 25° 43'N; north
of latitude 29°55'N and longitude 88°45.6'W, the eastern boundary is the three nautical mile line forming the eastern border
of Louisiana in areas bordered by federal waters or the officially recognized boundary between the two states within areas
of the states' jurisdiction.
• For Mississippi: The western boundary is the eastern boundary of Louisiana noted above and the eastern limit is
longitude 88° 23'W south from the state line between Mississippi and Alabama at 30°9'N to the EEZ boundary at 25°42'N.
• For Alabama: The western boundary is the eastern boundary of Mississippi noted above and the eastern border is
longitude 87°3.4'W south from the state border between Alabama and Florida at 30°8'N to the EEZ boundary at 25°56'N.
• For Florida: The western border is the eastern border of Alabama noted above and the southern border extending
into the Straits of Florida is the EEZ boundary.
Pelagic Trips: (web-master note: this section is of course out of date and is only provided as historical context)
Currently, the only regularly scheduled birding trips venturing beyond the continental shelf depart from Port O'Connor,
Texas, and Venice, Louisiana; trips to the Dry Tortugas departing from Key West, Florida, often travel at the edge of
the shelf. From Venice, Mississippi birders could use the same arrangements to get to Mississippi waters, with some of
the best pelagic birding areas in the Gulf, in two-and-one-half hours' travel time. Alabama birders can go south about
60 nautical miles to the 1,000 meter water depth usually needed for birds such as Band-rumped Storm-Petrel and 90 nautical
miles south to the 2,000-meter con-tour. A similarly long trip is needed from the western Panhandle of Florida. South
of the Panhandle, day trips would not be very feasible, but trips to the Florida Escarpment area have the potential
for incredible birding (Red-footed Boobies, both tropicbirds, Black-capped Petrels, etc.); perhaps after the Dry
Tortugas migration season, one of the boats birders use there could be chartered for a two-day trip to this area.
Although the EEZ limits birding in the Straits of Florida, a trip taken less than 45 nautical miles due south from
Key West could reach waters with a depth of 1,500 meters within US boundaries. This area will probably produce
Band-rumped Storm-Petrels on most trips from late April through early September and should regularly produce
tropicbird sightings.
Small groups of birders willing to pay much more than the cost for one of the Port O'Connor or Venice trips can
arrange trips for up to six persons on boats used for marlin fishing; any port from Port O'Connor south to the
Mexican border on the Texas Coast (Port Mansfield has several well-suited craft) and in the Venice area in Louisiana
can provide these boats; they are probably available in the Pensacola area also. You should try to find a boat at
least 30' long capable of going a minimum of 20 knots per hour. You must explain to the captain that you expect to
travel 20+ knots per hour for most of the day and be sure that you and the captain are discussing the same type of
mile (statute vs. nautical). Tipping the captain and crew is customary. You should be familiar with the area's
bathemetry to plan your destination, and you should record the time, latitude, and longitude for your sightings
and send your records to the appropriate state records committee.
Marine Mammals and Other Wildlife
Knowledge of Gulf cetaceans has paralleled that of pelagic seabirds. Before the early 1980s, the area was not
considered a promising place to spot marine mammals. Recent research done by the US Fish and Wildlife Service,
the National Marine Fisheries Service, and Texas A&M has shown just the opposite to be true. At least 27 species
of marine mammals have been spotted.
Although the baleen whales are rare here, many of the toothed whales are common. Species which are not seen
regularly off other US coastal areas—such as Pantropical Spotted Dolphin, Clymene Dolphin, Striped Dolphin,
and Rough-toothed Dolphins—are fairly common in the Gulf. The area off the mouth of the Mississippi may be
one of the best places in the world to observe Sperm Whale. Table 2 lists species recorded here; these species
are year-round inhabitants of the Gulf. Most pelagic birding trips produce sightings of several species of cetaceans.
Other creatures generate interest among birders during Gulf pelagic trips. The Whale Shark, the world's largest
fish, is common in Gulf waters and is usually found in association with schools of Yellow-finned and Black-finned Tuna;
after birders have gotten their fill of seeing Bridled and Sooty Terns and Audubon's and other shearwaters feeding over
a tuna school, the sight of a 35-foot fish gliding by the boat creates a pleasant diversion. Many species of flying fish
are found here, and billfish such as Sailfish and Blue Marlin are often seen. Occasionally, a large sea turtle (the
Leatherback is the most common in pelagic waters) will reward observers.
Summary
Although true pelagic birding in the Gulf of Mexico is relatively new and bird numbers are not as high as Monterey Bay,
Westport, or Cape Hatteras, a pelagic trip here has its own unique qualities. These trips usually produce good views of
birds often uncommon elsewhere in the US and also provide natural history experiences not available in other areas. For
those birders who desire to be true ornithological pioneers, the Gulf of Mexico is a wilderness with many discoveries
still to come.
About the authors; Dwight Peake has participated in most of the deepwater birding trips in the Gulf during the past five years. As a bird
observer for the Texas A&M University for their GulfCet I project, he spent several weeks at sea in The Gulf during
1993 and 1994. He has published and presented scientific papers on the birds of the Gulf, has organized Texas pelagic
trips with Mark Elwonger during 1994 and 1995, and encourages birders in other Gulf states to increase pelagic birding
trips off their coast.
Mark Elwonger has birded the central Texas coast for over 20 years and is author and publisher of Finding Birds on the
Central Texas Coast. He has organized and led trips for Avian Adventures for five years.
The authors would like to express their appreciation to: Giff Beaton for his helpful review, comments, and suggestions;
Greg Lasley for his photographs of Cory's and Audubon's Shearwaters; and Terry O'Nele for her drawing of a Bridled Tern.
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Washington, DC. FWS/OBS-82/01. 637 pp.
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