This is an introductory posting about the San Diego Zoo Institute for Conservation Research’s California Least Tern and Western Snowy Plover project. That is a mouthful—usually we just call it the terns and plovers project! Even though this is the first blog about the project, the Institute for Conservation Research has been involved with terns and plovers for many years. This year I joined the team to monitor the populations of these birds at two local bases, Navy Base Coronado (NBC) and Marine Corps Base Camp Pendleton (MCBCP). Military bases are an important part of the conservation of many species, because they have large areas of undeveloped habitat.
California least terns are small, elegant birds. They nest in colonies and used to nest all along the California coast. Now, they are restricted to just a few areas. NBC and MCBCP are the most important nesting areas for this species. In fact, approximately 35 percent of the entire population of California least terns nest at the two bases. The bases are also important for the western snowy plover. Even though they have only around 13 percent of the entire Pacific coast population, a large number of young are produced there.
Both of the species nest on the beach, and that can cause conflicts, because humans also like to use the beach. If you’ve walked along the beach, you may have seen a western snowy plover. They are slightly smaller than the much more common sanderling. Those are the birds you see in flocks chasing the waves. The plovers nest in the dunes. Their strategy is to be very secretive. When sitting, they can be mistaken for a lump of sand. We have seen many people walk by the plovers and not even realize that a bird was there. They have a very simple nest scraped out of the sand and their eggs are very cryptic. When they see a predator (like a human) coming, they quietly get off their nest and walk away. After the predator has passed, they slip back onto their nest.
Military training and cryptic birds nesting—that does not sound like a recipe for success, but, in fact, the Navy, Marine Corps, U.S. Fish and Wildlife Service, and their partners (including us), have worked together for decades to make this a successful program contributing to the recovery of these sensitive species. Our job is to work with the military personnel to monitor the birds and reduce the effects of training. How does that work? We go out and survey the areas and find the nests of the birds. We relay that information to the military, and they know what areas to avoid.
But both the Institute and the military do even more. Both bases have set aside and maintain some areas that are reserved just for the birds (more on all that the military does to help the birds in a future posting). We also want to determine what we can do so that the birds will thrive. For this, we monitor the nests and determine what happens to the nests. We also have some research projects looking at various aspects of the breeding biology of the birds to determine what influences their reproductive success (how many young they produce). You’ll hear more about those in later blogs.
The plover nesting season has already started, and a few nests have hatched. In addition to protecting the nests from being accidentally stepped on, we also protect some nests from predators. For both species, new predators are a common threat. The populations of American crows and common ravens have increased dramatically, and they love plover eggs. To combat this threat, we protect the nests by placing a mini-exclosure over the nest. These structures exclude most predators, but the plovers can easily walk between the wires.
The bases are large, so we have a team to survey the areas. In future blogs, you will be hearing from some of the others on the team and their experiences, so check back often!
Jeanette Boylan, Ph.D., is a conservation program manager with the San Diego Zoo Institute for Conservation Research.