New York Natural Heritage Program
Gull-billed Tern
Gelochelidon nilotica (Gmelin, 1789)

Threats [-]
Although Gull-billed Terns don't occur in large numbers in New York, populations may be threatened by habitat loss and human disturbance. A combination of factors may contribute to the dramatic declines of coastal salt marsh, that Gull-billed terns use for both nesting and foraging, on Long Island over the last 50 years (Hartig 2002). Changes to hydrologic processes resulting from coastal developement coupled with increases in sedimentary sulfide associated with human development are also believed to play primary roles in the decline of coastal salt marsh (Montalto and Steenhuis 2004, Kolker 2005). Sea-level rise and increased storms and flooding due to global climate change ia also a threat. Gull-billed Terns are particularly sensitive to disturbance and may abandon nests more readily than other tern species (Molina et al. 2009). Recreational boaters driving at high speeds or anchoring near salt marsh islands may disrupt terns from parental care of eggs and chicks leaving them vulnerable to predation. If colonies were to reestablish on beaches in New York they may be restricted by available habitat that is undeveloped and free of disturbance from recreational beachgoers and beach driving.

Conservation Strategies and Management Practices [-]
Management for Gull-billed Terns requires both the protection of existing colonies to enable populations to perpetuate and grow, and the restoration and protection of habitat for terns to move into as populations expand or disturbed colonies need to relocate. Discouraging gull colonies at some locations may be necessary to reestablish previous nesting locations and can be done through a variety of methods including establishing a monofilament grid over the area, culling, or disturbance by dogs (Kress et al. 1983, Kress 1997, Nisbet 2002, Blokpoel et al. 1997). Managing predators may be effective in certain circumstances where nest predation is high (Molina et al. 2010). Maintaining and protecting habitat at a number of suitable nesting locations is ideal even if some sites are temporarily unoccupied to allow colonies to relocate when disturbance occurs. Posting educational signs just prior to the nesting season has been an effective method at limiting human disturbance to colonies of other tern species on beaches (Burger 1989).

Research Needs [-]
At a minimum, continued monitoring of known nesting locations in New York and inventory of past and potential nesting locations is needed. Information on reproductive success in addition to the population index counts that are conducted annually by NY DEC would be useful to determine trends in productivity. If breeding success is deemed to be low, then threats to individual colonies may be identified and management actions can be taken if needed. Migration routes, stopover locations, and overwintering sites need to be determined especially along the Pacific and Mexican coasts (Molina et al. 2009). More research and monitoring of environmental toxin loads, genetic research on subspecies distributions, and dermining productivity of roof nests in the southeastern U.S. are also priorities (Molina et al. 2009).