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New Research Tests a Common Assumption about Protecting Birds

A recent study sheds light on the value of protected areas like national parks for conserving wild birds, with some surprising results.

By Jessica Weinberg McClosky
Small, yellow-orange bird with a narrow, pinkish beak.
Orange-crowned warblers are migrants. They spend the summer breeding and nesting in the western U.S. and Canada and the winter hunting insects in the southern U.S., Mexico, and Central America. Contrary to what researchers thought, they and other migrants seemed to benefit just as much from partial protection as birds that spend their whole lives in protected areas.

Image © Mark Dettling

Wherever we live, birds are our neighbors. So much so, we may overlook them. But when we do notice birds, they can be fascinating. Mark Dettling is an avian ecologist with Point Blue Conservation Science. “There's such varied behavior across all the different species,” Dettling said when I asked why he studies birds. “I want them to be able to continue into the future so that other people can see them.”

We all assume that protected areas like national parks safeguard wild bird populations. It seems kind of obvious, right? Until recently, assumptions about the benefits of protected areas for wild birds were all we had. But in a newly published paper in the journal, Ornithological Applications, Dettling and his colleagues lend support to those assumptions, well—mostly.

The Three-Billion Bird Question

The issue of conserving wild birds is urgent, because across North America, they are not doing well. By one estimate, one in four, or nearly three billion birds in total, have vanished from U.S. and Canadian fields and forests since 1970. There are important steps we can take as individuals to help fight that trend, like making small changes to our windows to prevent bird collisions. But such a huge, widespread problem also demands landscape-scale solutions. Land managers and conservationists have long assumed that more and bigger protected areas are key. But how well do protected areas actually work when it comes to conserving bird populations? Do they help all species equally? Does it matter if the birds are migratory, or if they prefer a particular habitat type?

Dettling and his coauthors thought some of their data would help answer those questions. This was information they had compiled over decades in collaboration with the National Park Service’s San Francisco Bay Area Inventory and Monitoring Network. Yet surely other scientists had already covered those bases? “It seems like this simple question, like...of course [protected areas] work,” Dettling said. “But you know, when we started looking, we weren't finding a lot of literature that really evaluated that.” What they did find were a couple of systematic reviews (collections of all relevant published studies on a topic). These were inconclusive, because they lacked studies with rigorous comparisons of protected areas versus unprotected areas. The seemingly simple question beckoned.

Comparing Two Key Data Sets

The data the paper’s authors had in mind had been collected through point counts by Point Blue staff in Golden Gate National Recreation Area, Point Reyes National Seashore, and neighboring state and local parks, since 1997. More recently, this data gathering project became a part of the San Francisco Bay Area Network’s long-term Landbird Monitoring Program, which focuses on tracking birds in riparian habitats (next to a river or stream).

But wait, what’s a point count? A point count is when someone stands in a set spot for a set amount of time, and records all the birds they can see or hear, plus how far away they are. “We start right after sunrise,” Dettling explained, “and in these riparian areas, it can be overwhelming at times, just because there's lots of different birds. You kind of have to have had your coffee and be on your toes, ready for that first point.”

Though the point counts aren’t always easy, collecting enough data can be even more challenging. Without enough data, researchers can describe bird populations at moments in time, but they can’t answer more complicated questions about population trends. As Dettling told me, “those long term data sets are usually pretty difficult to maintain and keep getting funding for, which is why the inventory and monitoring program is such an important part of getting this project done.”

So, long-term data to look at bird trends in protected areas: check. But to continue with their study, the Point Blue researchers also needed to compare the land bird program data with long-term trend data from unprotected areas. They turned to data from two North American Breeding Bird Survey regions, one encompassing Point Reyes and Golden Gate, and another just to the north. Founded in 1966, the breeding bird survey is a citizen science project led by the U.S. Geological Survey. Like the land bird program, it uses point counts, making it easier to compare data from the two programs.

Person pauses on a trail beside a dry creek bed to get a reading from his hand-held GPS device.
Avian ecologist Mark Dettling locates a point count station at Pinnacles National Park. Scientists return to the same spot every year to count birds so that they can draw stronger conclusions about how bird populations are changing between years. To gather the data they used in this study, scientists returned to the same point count stations in Golden Gate and Point Reyes for 23 years.

Image © Point Blue Conservation Science / Megan Elrod

Reassuring Results—and One Unsettling Surprise

After comparing trends for 14 bird species in the parks with trends for those larger regions, the Point Blue researchers found that people's gut instincts about parks benefitting birds are largely correct. From 1997 to 2019, nine of the 14 species fared better in the protected areas. Trends for three other species were similar for the protected areas and the larger regions.

But (you knew there was a “but,” right?) no one expected to discover that two species, the black-headed grosbeak and the olive-sided flycatcher, fared worse in the protected areas. “We think we are providing all the habitat requirements necessary, but apparently for those two species, there's something in their life cycle that is affecting them more,” said Dettling. “The more surprising one, maybe, was the black-headed grosbeak. It's a species that is tied pretty closely to riparian habitats where our surveys were.”

So far, the researchers aren’t sure what explains those findings, though they do think further monitoring in more habitats, and closer looks at the species’ migration routes, breeding grounds, and wintering grounds could shed more light on the situation.

There was another, more pleasant surprise. The paper’s authors thought that the resident birds in their study, like spotted towhees and wrentits, would experience the strongest benefits from protected areas. After all, resident birds may spend their entire lives in protected areas. Migratory species, on the other hand, like Swainson’s thrushes and orange-crowned warblers, spend at least half of each year in other places. In fact, Dettling and his colleagues showed that both groups experienced similarly strong benefits.

Fourteen small photos of different bird species in three rows. The nine on top are doing better in protected areas compared to larger Breeding Bird Survey regions. The three in the middle are doing similarly. The two on the bottom are doing worse.
The study found that the nine birds in the top row all did better in Golden Gate, Point Reyes, and nearby parks than they did in larger Breeding Bird Survey regions in California. The three in the middle did similarly well. Surprisingly, the two on the bottom, black-headed grosbeaks and olive-sided flycatchers, fared worse. So far, researchers can't tell why. Hover the cursor over a bird to learn its name. Clicking on a bird will take you to the Audubon field guide page for that species.

Images © Mark Dettling, © Jessica Weinberg McClosky, © Philip Georgakakos, and © R.M. Yoshihara.

Woodpecker with a black and white striped back and a red crest clinging to a tree trunk. Bird with a light breast and a spotted throat, perched on a branch. Small, yellow-orange bird and a narrow, pinkish beak. Small bird with a black and white head and a chestnut back. Small yellow bird with a black cap on it's head. Grayish bird with a lighter eyebrow stripe, getting ready to fly from it's perch. Small but chunky-looking bird with a striking light yellow iris, holding it's tail almost straight up. Small brown and cream-colored bird with a light eyebrow stripe and black bars on its tail. Bird with a black head, black and white spotted back, rusty feathers under its wings, and striking red eyes. Bright blue and gray bird with a heafty black beak. Small brown and white bird singing its heart out. Yellow bird with a dark, black facemask around its black eyes, resting on one leg. Bird with a thick, triangular beak, a brown and white striped head, and a peack-colored breast. Olive-gray bird with a small crest raised on it's head, perched at the top of a bare branch.

Protected Areas Are Not Enough

Given their findings, the researchers think more protected areas would indeed be a win for birds. “Programs like the 30 by 30 would help bird populations on a much larger scale if we could get a lot more land under certain protections,” said Dettling.

Still, Dettling and his co-authors don’t see protected areas as sufficient, or as a solution for all bird species. Some birds could require conservation measures tailored to their particular challenges, perhaps unrelated to insufficient habitat. Plus, the researchers can’t be sure that the protected area benefits they found will continue to hold. It’s possible that intensifying climate change impacts could weaken them in the years ahead.

Good Solutions Need Good Data

One more takeaway from this project is that continued long-term monitoring is important. For example, the researchers had to exclude Pinnacles National Park from their analysis, even though the riparian habitat is a little different there, and they would have loved to include it. There just weren’t enough years of Pinnacles data yet to detect trends.

More monitoring could also mean enough data to include more bird species in future analyses, or the ability to see how population trends are affected by different kinds of climate conditions. “It's going to be interesting to continue to monitor to see how these species react to wetter years or drier years or just the change in plant species because of those weather dynamics,” said Dettling.

No one can be sure what questions will be the most pressing for bird conservation in another 10, 20, or 50 years. But chances are, as long as scientists keep collecting long-term monitoring data, another generation of researchers will be well equipped to answer them.


Smiling woman with long brown hair holds camera pointed toward yellow and red flower while crouched on the ground in a grassy field

About the author

Jessica Weinberg McClosky is a science communications specialist with the San Francisco Bay Area Inventory & Monitoring Network. She’s often working on either a new story map or a new issue of the San Francisco Bay Area Nature & Science Monthly Newsletter/Blog. Outside of work, Jessica enjoys nature photography and exploring new hiking trails with her family. Photo courtesy of David McClosky.

Golden Gate National Recreation Area, Pinnacles National Park, Point Reyes National Seashore

Last updated: August 4, 2022