Photos of the Long Island Sound

Status and Trends: LISS Environmental Indicators

Type of Indicators: Health/Condition Response/Performance Socio-Economic Historical/Background

Least Terns

Source: CTDEEP Wildlife Division and NYSDEC

Least Terns (Breeding Pairs)
CT NY Total
1991 627  —
1992 655  —
1993 175  —
1994 334  —
1995 538  —
1996 461  —
1997 403  —
1998 447  —
1999 335  —
2000 239 541 780
2001 175 828 1003
2002 224 767 991
2003 197 650 847
2004 158 548 706
2005 246 824 1070
2006 144 1211 1355
2007 147 691 838
2008 252 1073 1325
2009 90 843 933
2010 119 1000 1119
2011 361  954  1315

What is the Least Tern?

The least tern (Sternula antillarum) is the smallest of American terns. They are migratory birds that winter in Central America, the Caribbean, and Northern South America. Breeding colonies appear along either marine or estuarine shores of the coastal United States, or on sandbar islands in large rivers throughout the interior of the United States. The least tern hunts primarily in shallow estuaries and lagoons, where small fish are abundant. Once they have spotted their prey they plunge into the water in a spectacular aerial dive to catch it.  The least tern’s favored nesting habitat is prized for human recreation, residential development, and alteration by water diversion, which interferes with successful nesting in many areas.

What does this indicate?

Abundance of least terns indicates whether there is sufficient protected beach habitat for coastal birds and sufficient food supply of forage fish in coastal waters.

Status

Least terns, a threatened species in New York and Connecticut, live in large colonies on the beach and plunge into nearby waters for food. Predators, human disturbances, and tidal flooding can disrupt tern nesting sites, but the terns have the potential to recolonize in other beaches within a four-state region that also includes Rhode Island and Massachusetts. The least tern population has remained relatively stable among the southern New England/New York region since 1990. In 2011, there were 7,078 least tern pairs in the region, 735 pairs above the 20-year average.

In 2011, after several years of  general decline, the least tern count in Connecticut was considerably higher than in the two years prior and this higher number of terns is encouraging (although it may show up as a decrease in a neighboring state). In 2011, approximately 361 pairs of least terns nested along the shoreline in Connecticut, an increase of 401 percent increase from 2009 when there were 90 pairs. The largest number of terns were found at Sandy Point in West Haven where more than 400 adults were observed there in May and June. In New York, the least tern population has been stable over time, including at nesting sites in Long Island Sound and other North Shore sites.

 

data notes

The New York dataset for this indicator includes monitored sites on the North Shore of Long Island (Long Island Sound) and additional sites in Peconic Bay and Shelter Island in the North Fork of Long Island.  LISS assesses this entire sub-region of Long Island for the least tern indicator because the birds frequently re-nest and might move from a Peconic Bay or Shelter Island beach to a Long Island Sound beach and back in the course of a year. LISS also maintains the same dataset for its other beach-nesting indicator, piping plovers.

New York data from 1990 to 2001 is currently not available.

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Barrier beach habitat is an important breeding ground for many coastal birds. The photo shows least terns at one of these beaches, Sandy Point in West Haven, Connecticut. The least tern is considered a threatened species in New York and Connecticut. Photo by Julian Hough.

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