Places We Protect

Shamrock Island Preserve


A variety of waterbirds wade through the shore with thick green brush in the background.
Shamrock Island Water birds flock to this colonial bird nesting island. © Erika Nortemann/The Nature Conservancy

Shamrock Island Preserve is an important colonial bird-nesting island on the Texas coast.



On the eastern shore of Corpus Christi Bay lies one of the most important colonial bird-nesting islands on the Texas coast. The island was once an extensive peninsula of Mustang Island, but in the 1950s, a series of navigational channels were dug into the landmass, significantly weakening it. In early August of 1970, Hurricane Celia's path of destruction completely separated the peninsula into an island, creating a prime rookery nearly free of human disturbance and predatory wildlife. Nineteen bird species now nest on The Nature Conservancy's (TNC) 110-acre Shamrock Island Preserve each year, some of which have thousands of nesting pairs.

Grassland plants and shrubs help stabilize Shamrock Island's dunes and other substrates, slowing wind and water erosion. Seagrass meadows provide essential forage for redhead ducks, as well as nursery, foraging and refuge areas for many estuarine fish and invertebrates. In addition, resident and migratory species depend on the preserve’s land-based plants for nesting sites, food and shelter.

Among the plant communities of conservation interest are seaside little bluestem, gulfdune crowngrass, sea oats, shoal grass and Texas stonecrop. In addition, sand brazos-mint, crown coreopsis, velvet spurge, coastal plain umbrella-sedge, Jones' nailwort and Indianola beaksedge are also often found here.




110 acres

Explore our work in this region

A bird chick with fuzzy feathers and an open beak.
HATCHED Each year, numerous chicks hatch on Shamrock Island Preserve, like this young Caspian tern. © Rich Kostecke

Why This Place Matters

Shamrock Island Preserve supports a number of rare bird species, such as the state-threatened reddish egret and white-faced ibis. The island also consists of quality beach habitat used by skimmers and four species of terns, including more than 8,000 pairs of royal terns in some years. Grassy flats can harbor an estimated 6,000 pairs of laughing gulls, while brushy uplands provide nesting cover for many other waterbirds. These visitors include great, little blue and tricolored herons, as well as black-crowned night herons, great and snowy egrets and roseate spoonbills.

Nature has helped make Shamrock Island a leading site for colonial waterbirds with pristine foraging habitat located nearby.  The preserve is also farther removed from threats such as pollution and oil spills, which are likelier to affect rookeries off Louisiana’s coast. However, the island is unusual in that it lacks a submerged sandbar just offshore. During calmer days, gentle waves generally roll across a sandbar and replenish grains of sand pulled from beaches during storms or heavier waves.

Without a sandbar, erosion can steal up to 14 feet of Shamrock Island’s southwest shoreline in a year—and if left unchecked, this erosion could seriously reduce the island's size, putting nesting species at risk of losing their toehold here.

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Photos from Shamrock Island Preserve

Discover the diverse wildlife at this critical colonial bird nesting island.

Three white birds with orange faces and long, slender beaks sit in green vegetation.
A pink feathered bird stands bent over in shallow, calm water with its spoon-like beak in the water.
At least 8 adult brown pelicans stand in the sand on the shore, wading into ocean waters.
Two volunteers crouch near the shore, planting small, green seedlings in the sand.
Two featherless, white baby pelicans huddle together in a nest amongst green vegetation
Two gray birds with white bellies stare off into the distance as they sit amongst green vegetation.
Two birds with brown bodies, white necks, brown crowns and orange beaks stand on a branch.
Over a dozen small white and black birds with bright orange beaks sit on nests in the sand.
Two white-colored reddish egrets sit at the top of green vegetation against a blue sky.
Five large, brown pelicans sit on low lying branches along the shore.
Five volunteers plant native seedlings on the beach.
RESTORING HABITAT Gulf Corps volunteers plant native species at Shamrock Island Preserve. © R.J. Hinkle

What TNC Is Doing

Though nature is resilient, it sometimes needs our help to thrive. Since acquiring Shamrock Island Preserve, TNC and its conservation partners have developed a long-term habitat restoration and protection program here. Much of this work hinges on TNC’s installation of 27 breakwaters just offshore, which have been protecting the island’s shoreline from erosion.

The reinforced rock walls slow waves as they roll in, allowing sediment to fall from the water and settle. In addition to helping replenish sand, the protective rock walls create excellent conditions for the establishment of seagrass habitat. That seagrass helps anchor sand and sediment to the ocean floor, an additional step in keeping underwater erosion in check.

Moreover, protecting the island from disturbance and trespassing during nesting season is one of TNC's highest priorities. When birds are disturbed by boaters or fishermen and leave their nests, eggs will overheat in less than three minutes. Enhancing nesting habitat and addressing marine and bay debris, which may wash up on shore, are also helping ensure the survival of the many bird species that make Shamrock Island their home. 

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Shamrock Island Preserve is always closed to the public. 

Access to the island is strictly prohibited during the February through August nesting season, unless prior arrangements are made with TNC. For more information, contact Coastal Plains Project Director Sonia Nájera (snajera@TNC.ORG).