Colonial Nesting Birds

A Great White Heron is perched on top of mangrove trees.
A Great White Heron is perched on top of mangrove trees at Ragged Key 5, in Biscayne National Park.

NPS Photo/Robert Muxo

Colonial nesting birds such as great egrets, white ibis, snowy egrets, roseate spoonbills, brown pelicans, cormorants, and sooty terns, are very important as vital signs of the health of our national parks. The presence of colonial nesting birds, the size and distribution of their nesting colonies and the reproductive success of their nests indicate that the surrounding habitat is able to support these energy intensive activities. These birds must acquire large quantities of high quality food during the nesting season as they select mates, build nests, lay eggs, and rear chicks. Colonies are susceptible to disturbance and predation pressure. Thus, a decrease in nesting effort and nesting success as well as local population declines may indicate that the ecosystem is not functioning properly. Many of these colonial nesting species have already experienced declines and are listed as species of special concern, threatened, or endangered. Our goal is to track the status and trend by monitoring the number of occupied and non-occupied active nests in a colony.

Our monitoring objective is:
  • What are the status and trends in colony size, distribution, and active nest of specific colonial nesting birds?

SFCN developed a monitoring protocol and conducts monthly monitoring of colonial nesting birds in Biscayne National Park (BISC). Bi-annual reconnaissance helicopter flights are conducted park-wide in the spring and fall to determine colony locations. Once colonies’ locations are determined, monthly monitoring commences and involves taking photographs from a helicopter of nesting activities. The photographs are analyzed for active nests and compared sequentially to ensure nests are not double-counted. The information is then recorded to help determine trends in nesting populations of colonial birds in Biscayne National Park. A boat survey was conducted in April 2011 to compare data collected from a boat to the data collected from a helicopter flight the same month. Once again the helicopter was shown to provide the best platform for gathering nesting quantities in Biscayne National Park. Annual peak nest counts are a primary summary metric being considered for evaluating trends. The species of birds in Biscayne National Park can be broken down into three functional types based on their feeding behavior: divers, stalk and strike, and tactile. Primary species recorded include Double-crested Cormorants, Great Blue Heron, Great Egret, Great White Heron, Roseate Spoonbill, and White Ibis. Small egrets and darker herons (e.g., little blue heron) are not detectable and often nest deeper within the canopy and are difficult to count accurately so they are not included. 2013 marks the completion of the fifth year of colonial bird monitoring in Biscayne National Park by the South Florida/Caribbean Network.

Colonial Nesting Birds publications

Find all monitoring reports, protocols, and resource briefs below.

Colonial Nesting Birds image gallery

Find pictures of colonial nesting birds below.

Last updated: March 30, 2021