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John Sterling

Wildlife Biologist
I really love the birds.

John Sterling is an independent wildlife biologist whose clients include The Nature Conservancy, The Smithsonian Migratory Bird Center, Audubon Canyon Ranch, Kern Water Bank, and the California Rice Commission. His activities include leading international tours, wildlife photography, teaching classes on bird identification, surveying birds, and writing environmental reports.  His website is



What do you enjoy most about studying, thinking, and writing about birds?


The thing that keeps me going is: the more you learn, the more you find out that you need to learn more. It’s like you open up a door, and then there are three more doors open. It’s almost an infinite amount of knowledge that you can strive for. It’s very exciting.


What would you say is the relationship between birds, where they hang out, and the health of the habitat?


It depends on the bird. In some areas, what you think would be an unhealthy riparian habitat might be a really good habitat for some species. The big conservation concern is for bird species that are specialized on either old growth (large, mature valley oak trees) or really healthy riparian forests. If there’s logging, downed trees, or diseased trees, then you’ll have fewer of those birds. But other birds will thrive in those altered habitats in certain situations, so it really depends.


Some people talk about this preserve as being a paradise for birds. Is it? What makes it a paradise?


The Cache Creek Preserve is a paradise for birds. It’s a fairly intact ecosystem. There is definitely room for improvement, but there are [also] a lot of improvements that have been made over the years. It’s an area where we might see Yellow billed Cuckoos return in the future. That was a bird that has been extirpated from this area several decades ago. Also, Bell’s Vireos were extirpated from the Central Valley back in the 1940s and 1950s, and we’re starting to see a few of them return to the valley. I half expect that they will be found on or near the preserve in a few years.  It would almost be the equivalent of having an extinct bird return to this area, because no one ever thought that they would return. Conservation efforts have really helped them along, and birds are really making a comeback. It’s very, very exciting.


Would you say that the work that’s been done by the Preserve is a leading edge in supporting the restoration of habitat for extirpated birds?


The Preserve has done wonders with trying to eliminate exotic weed species throughout the Cache Creek area, which has been very important. It’s been on the leading edge for those efforts throughout California, so that work is very, very important if it can be shown that we can really eliminate the salt cedar and common reed from these areas. It would bolster a lot of efforts throughout the west to eliminate these plants that have really, really damaged the ecosystem.

How can we understand the history of this place by the birds that are here now?


Birds help us understand the history of Cache Creek not only through the birds that are here but also the birds that are not here now. We know that in the past there were bald eagles and osprey. Those birds declined drastically in the 1960s from DDT poisoning and have been making a comeback. They are spreading south through the Central Valley, and they’re breeding closer and closer to this area. There was a nest of bald eagles in upper Cache Creek last year, so I think it’s only a matter of time until they return. So it’s an interesting story of seeing the history of how we affected two bird species through poisoning, and we eliminated that poison from the environment and are seeing a comeback for those birds.


Why are birds important to humans? Why should we care about birds?


People should care about birds because they are important indicators of environmental health. If you have a loss of insects or a loss of fruit or any kind of prey, the bird populations will decline, and it’s easy to notice declines in birds, because they’re so prevalent. For an ecosystem, they do provide a lot of services. They eat a lot of insects, especially a lot of pest insects. They’re very good at helping plants distribute seeds long distances, especially the fruit eating birds. The raptors (owls and hawks) play an important role in rodent control in a lot of areas. In farmers’ fields they eat a lot of voles and pocket gophers. Hummingbirds and some other birds that eat nectar will pollinate flowers. There are many different ecosystem roles that birds play.


Can you tell me about a bird species that you would find in a riparian habitat?


The yellow-breasted chat was historically thought to be in the warbler family but is actually a fairly different bird. It is much larger than other warblers and very different vocally. They have a bright yellow chest and are grey in the back and on the head. They’re fairly large, almost the size of a robin. They need really dense willow and blackberry scrub habitats, so they nest really close to the ground and need really thick, dense vegetation. It’s a bird that has been mostly lost in Central Valley because of brown-headed cowbirds that have moved into the valley in the 20th century. The female brown-headed cowbird will lay an egg in the nest of a chat or some other bird that has an open-cut nest, and their egg will hatch before the chat’s babies are hatched. The young cowbird will either kick out the eggs, or else once the babies are hatched, will either kick out the babies or outcompete them for food from their mother. So a lot of chats have been lost, [but] they do occur in a few areas. Cache Creek is an area [that] they could return to in the future. I know they’ve nested in upper Putah Creek in the past and in scattered areas in the Central Valley. But I could imagine them being here in the foreseeable future. It would be a really good conservation success story if we had them, and they are certainly managing in the Preserve properly by having that kind of vegetation. We’re just hoping that birds will come back.

Written by: 
Tracey Lin

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