“Tern Town”, located along the eastern side of the San Francisco Bay, provides island nesting habitat for three special status species. Since 2015, and for a total of six breeding seasons, the endangered California Least Tern (Sternula antillarum browni), the threatened Western Snowy Plover (Charadrius alexandrinus nivosus) and species of special concern the Black Skimmer (Rynchops niger) have nested successfully, in association with American Avocet (Recurvirostra americana) and Black-necked Stilt (Himantopus mexicanus). On June 6, 2022 the Black Oystercatcher (Haematopus bachmani) which is uncommon within its range and is typically limited to the rocky intertidal established a nest, on the island. Black Oystercatchers have been documented nesting near gulls and terns (Sterna spp.) and are known to use their bills to jab at other species chicks that wander into their territory. We witnessed no such incident, and this is the first documented occurrence of oystercatchers successfully nesting and fledgling young with California Least Terns. Diet trend data showed the oystercatchers forage on, in decreasing order of abundance: Japanese Little-necked Clam, Ribbed Mussel, and Bent-nose Clam, Limpets. This site-specific information on breeding Black Oystercatchers supports recovery plan tasks that are consistent with managing habitat for near California Least Tern, Western Snowy Plover and Black Skimmer.

David (AKA “DOC QUACK”) Riensche, a Certified Wildlife Biologist, is a Wildlife Biologist II for the East Bay Regional Park District where he has worked for over 34 years. For 25 years he has been a member of the Biology Department faculty at Las Positas College, where he teaches courses in biology, ecology, and vertebrate natural history. He is a recipient of The National Association for Interpretation (Region 9) – Outstanding Field Naturalist Award. David holds advanced degrees in both Natural Resource Management and Environmental Education, and an undergraduate degree in Biology (Wildlife). His current wildlife research and habitat restoration efforts are diverse.