Gulf of Mexico

Regional Sub-group

GOM SCAW Leads:

 

Amanda Hackney

(Black Cat GIS & Biological)

Jeff Gleason

(USFWS, Gulf Restoration Program)

 David Newstead

(Coastal Bend Bays & Estuaries Program)

Kacy Ray

(American Bird Conservancy)

Short-term Goals/Activities (2017-2020): ​

  1. Obtain the following information from GOM states, and regions (this may be in the form of links to existing web sites with contact information):

  2. Breeding metrics collected for each species;

  3. Data collection methods and protocols, by species;

  4. Data collection methods guidance documents/manuals;

  5. Existing breeding data/databases, by species;

  6. Future data needs, by species;

  7. Key threats affecting seabird breeding success;  

  8. Existing management, conservation, outreach efforts. 

 

Colonial Nesting Seabirds within GOM SCAW 
  • Double-crested cormorant

  • Laughing Gull

  • Common tern

  • Least tern

  • Black skimmer

  • Forster’s tern

  • Gull-billed tern

  • Caspian tern

  • Brown pelican

  • Royal tern

  • Sandwich tern

  • Sooty tern

  • Neotropic cormorant

Focal Species Highlights:

Double-crested Cormorant          Phalacrocorax auritus

This species of cormorant is an infrequent breeder in Texas, only 9 pairs were counted in 2011 with a record high of only 363 pairs in 2007 (TCWS 2011).  All of the larger colonies have been observed in the upper coast. During breeding season, these birds occupy a variety of habitats: ponds, lakes, artificial impoundments, slow moving rivers, lagoons, estuaries and open coastlines (Hatch and Weseloh 1999).  This bird generally feeds over shallow water (< 8m) and near the shoreline (<5 km away) (Hatch and Weseloh 1999).  Throughout its range, the species has been recorded as nesting on the ground, on cliffs, in trees and shrubs, on artificial nest structures, on transmission towers and abandoned wharves or bridges (Stenzel, Carter et al. 1995). When located in trees or large shrubs, a variety of species are utilized and the live plants are often killed by nesting activity after 3 to 10 years (Lemmon, Bugbee et al. 1994). Colonies are subject to mortalities caused by human disturbance; chicks are killed by exposure and eggs and young chicks are subject to predation (Hatch and Weseloh 1999).  One to five colonies have been counted each year from 2003 to 2013.  Only two colonies reported Double-crested cormorants in 2013: San Jacinto Monument (31 pairs) and West Bay Mooring Facility (1 pair).

Laughing Gull     Leucophaeus atricilla

The Laughing Gull has become one of the more successful species of subsidized wildlife on the coast, adapting well to the presence of humans and unnatural food sources. The species had a recent peak in Texas with 114,233 breeding pairs counted on the TCWS survey in 2002.  The largest colony was located on West Bay Bird Island in 2011 with a population of 11,300 pairs, or 14.7% of the entire 76,698 pairs counted that year (TCWS 2011). Laughing Gull populations expand or contract depending on availability of nesting sites, human persecution, and availability of food resources (supplemented by garbage) (Burger 1996).  The species breeds in a variety of habitats including salt marshes, rock or vegetated islands, sandy beaches or islands and dredge spoil islands (Burger 1996).  Foraging grounds include ocean, bays, river mouths, rivers, streams, plowed fields, marshes, grassy meadows, impoundments and landfills (Burger 1996). These gulls will engage in piracy at tern colonies with multiple gulls chasing a tern to successfully obtain a fish (Hatch 1970). Nests are built right before egg laying, with adults often adding material to a nest in response to rising water levels.  Peak hatching occurs from the end of May to early June in Texas with fledging occurring at 35-42 days (White, Mitchell et al. 1983).  Nest sites vary, but are usually low lying islands free of predators, often on mats of dead vegetation but can vary from bare sand and rocks to heavily vegetated areas (Burger 1996). The Laughing Gull causes problems in mixed species rookeries as a predator of eggs and chicks.  They are known to capitalize on disturbance caused by humans, taking the opportunity to steal eggs while adults of other species are off the nest. They also seem to be expanding into new mixed-species colonies, taking up valuable nesting space from other birds. Laughing Gull numbers have ranged between 40,000 and 114,000 pairs from 1973 to 2013.Between 40 and 74 colony sites per year were recorded for Laughing Gulls from 2003-2013.  In 2013 there were a total of 43,855 pairs recorded with the largest colonies being Shamrock Island (11,300 pairs) and North Deer Island (7,500 pairs).

Least Tern           Sternula antillarum

In the late seventies, the TCWS census indicated a significant decline of Least Tern breeding populations; numbers dropped from 4300 in 1973 to 380 pairs in 1978 (Brubeck, Thompson et al. 1981). However, because of the Least Tern’s nesting habitats, colonies are likely not well represented in the TCWS database and numbers could be underestimated. The species prefers to nest on relatively open sites on beaches and islands that are kept free of vegetation by natural scouring from tidal or river action (Thompson, Jackson et al. 1997).  Ideally a nest site is largely free of vegetation, above high water levels and safe from ground predators.  The Least Tern may change breeding locations frequently in response to changing environmental conditions and commonly uses sand, shell, or gravel as a nesting substrate (Thompson, Jackson et al. 1997).  Due to the high salinity of new dredge material inhibiting vegetation growth, the species readily uses newly created spoil islands. Preferred vegetation cover has been found to be 5-10% in New York (Gochfeld 1983) and 0.2-5% in California (Minsky 1987). Colony site tenacity has been found to be limited by changes in vegetation cover, predators, human disturbance, floods and colony size (Thompson, Jackson et al. 1997).  In marine populations, the Least Tern feeds in a variety of shallow water habitats including bays, lagoons, estuaries, river and creek mouths and individuals were observed to be most successful foraging in water >1 m deep (Thompson, Jackson et al. 1997).  Least Tern numbers hovered around 1,000 breeding pairs from 1999 to 2006. They dropped to a low of 239 pairs in 2009 and have been slowly increasing since.

Black Skimmer  Rynchops niger

Colony sites include barrier beaches, dredge spoil islands, shell banks, and salt marshes that are sparsely vegetated (<20% cover) with open sandy and/ or shelly areas (Gochfeld and Burger 1994). Skimmers will also use open parking lots, rooftops or bare spaces with a gravel substrate for nesting. Lack of vegetation cover is vital to colony site selection, skimmers tend to occupy areas with up to 10% vegetation and will actively avoid areas with >30% cover (Gochfeld and Burger 1994). Throughout most of their range, Black Skimmers nest in colonies with various tern species, deriving some protection from these more aggressive neighbors (Gochfeld and Burger 1994).  The species is becoming more susceptible to washouts as prime, higher elevation nesting locations are taken over by development and recreational pressures (Gochfeld and Burger 1994). On the Atlantic Coast, the presence of a gull colony on higher beaches will also discourage nesting by skimmers and terns (Burger and Gochfeld 1990). Foraging areas are often near the colony site and include tidal waters of bays, estuaries, lagoons, rivers and salt marsh pools, creeks and ditches where small fish are concentrated (Gochfeld and Burger 1994).  Over much of their range, skimmers nest with more aggressive tern species that provide early warning of intruders and that mob predators in large numbers (Gochfeld and Burger 1994). Texas populations are declining rapidly, total breeding pairs for the state dropped 67.1% from 10,821 in 1973 to 3,562 in 2012 (TCWS 2013). Number of breeding sites actually increased from 47 in 1973 to 61 colonies in 2012. The largest colony in the state for several years has been the Dow Chemical Company site in Freeport. The company has fenced off a former gravel parking lot, electrified the fence to protect against predators and minimizes human disturbance while the birds are nesting.  In 2013 it was the largest Black Skimmer colony in the state at 600 breeding pairs (TCWS 2013).

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