Establishing Forster's Tern Nesting Colonies

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Detailed Description

Scientists from the USGS Western Ecological Research Center (WERC) are conducting a "social attraction" study for seabirds in the Don Edwards San Francisco Bay National Wildlife Refuge. Historically, this region offered wetland habitats to local wildlife. With the introduction of industrial salt ponds and human development, however, much of this habitat was lost. Now, former salt ponds are being converted to a mix of restored tidal marsh and managed ponds for animals. USGS WERC scientists are using lifelike models of terns (small seabirds) and electronic call systems to draw Forster's terns to new habitat in managed ponds.


Date Taken:

Length: 00:02:32

Location Taken: San Francisco Bay, CA, US


[C. Alex Hartman]: Hello and welcome to the Don Edwards San Francisco Bay National Wildlife Refuge. My name is Alex Hartman and I am a biologist with the U.S. Geological Survey. Just behind me is the managed Pond A16 in the Alviso complex of the refuge and the site of our Forster’s Terns social attraction effort.


Islands within managed ponds like A16 have historically supported large numbers of breeding terns.


In 2012 the South Bay Salt Pond Restoration Project constructed 16 additional nesting islands within pond A16 in an effort to maintain waterbird breeding populations in South San Francisco Bay even as other managed ponds are restored to tidal marsh. Yet today, Forster’s terns have not returned to this historic nesting area where in some years over 300 hundred terns and avocets nested. Through a generous grant from the Santa Clara water district, USGS will be using social attraction to attempt to re-establish breeding colonies of Forster’s terns to pond A16.


Here is one of our Forster’s tern decoys. They are carved out of wood and painted to resemble real Forster’s terns as they would look sitting on their nests. On each of six islands, we are putting out 50 of these tern decoys, and anchoring them in place with rebar stakes.


On each of six islands with tern decoys, we will also deploy an electronic call system. These systems include a portable MP3 player with amplifier that is powered by two six-volt batteries and recharged using this solar panel array. Pre-recorded Forster’s tern colony calls are broadcast through two omnidirectional speakers that we place among the decoys. This system allows us to broadcast Forster’s tern colony calls continuously over the entire breeding system.


[Forster’s tern colony calls]


[C. Alex Hartman]: With the decoys and electronic call systems, these islands will look and sound like real Forster’s tern nesting colonies. With luck, Forster’s terns will find these colonies and nest here. USGS will monitor nesting activity on these and other islands within Pond A16 as well as other locations in South San Francisco Bay throughout the breeding season. Thank you for watching.


[Forster’s tern colony calls]


Credits: Many thanks to the Santa Clara Valley Water District, for providing funding for this project.


And to our partners:

U.S. Fish and Wildlife Service

Don Edwards San Francisco Bay National Wildlife Refuge

South Bay Salt Pond Restoration Project

San Francisco Bay Bird Observatory