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Why A Decrease In 3 Billion North American Birds Matters

 October 1, 2019 at 10:19 AM PDT

Speaker 1: 00:00 In the last 50 years, the number of birds in North America has declined by an estimated 3 billion. That's a 29% decrease. Researchers say this is a direct result of humans altering the natural world. Phillip unit is author of the San Diego County bird Atlas and a curator and specialist in California, birds at the San Diego natural history museum. As part of coverage from the KPBS climate change desk, Philip units spoke with Mark Sauer, host of the KPBS round table. Speaker 2: 00:32 We'll start with this study and the scope of the problem. How badly have bird populations declined in North America over the past half century? So the study that was just published by Cornell university suggests that a loss of on the order of 3 billion individuals covering something on the order of 75 to 80% of North America's species. Uh, so not all species are covered, but certainly by far most are indeed most especially VCs of grassland and forests, and they were hit the hardest, right? Right. The grassland species especially. What types of birds are we talking about? Meadowlarks Savanna, sparrows Redwing blackbirds. Now this study addresses the entire continent. If we were talking about California or San Diego, our emphasis would certainly shift, but we see that same theme play out in Southern California as well. Right. Well that was one of the questions I had for you to start with. San Diego County and of course folks who go to get out in a lot of the, the birders here, the amateur birders are, are very, uh, an intensely involved in this and in, in involved in the counseling. Speaker 2: 01:42 We'll get into that in a minute. But, uh, this is happening throughout the, the San Diego County region as well. Certainly many VCs have declined a severely in my lifetime. I look at the tri-colored Blackbird when I was a little kid in the 1960s. Huge flocks of them flying over my parents' house in city Heights. Now, uh, there's just a few scattered colonies. It's listed by the state of California. It's threatened, uh, just in the last year or so. And, uh, some other birds in California as well as you've seen the client statewide. Uh, certainly the burrowing owl, uh, the yellow billed cuckoo grass operas, Sparrow, California, Gnatcatcher. The list goes on and on. Of course, there's species that have increased as well. Everyone knows about the proliferation of the American Crow. Uh, we've also seen the Western Bluebird, uh, Allen's hummingbird Nadal's woodpecker, uh, increase. But the theme of this article was that the decrease is much outweigh the increases over the scope of the entire continent. Speaker 2: 02:55 And what are some of the key factors behind this massive decline in bird populations? Habitat loss to development to agriculture here in Southern California. Drought plays a significant role. Just in the last several years, uh, the fires have had a big effect and we studied the effect of those in some species, like the pygmy not ads and a mountain ticket. The California Thrasher that were very common became rare overnight and have recovered poorly in those burned areas. A habitat fragmentation. The Sage Sparrow horned Lark lesser Nighthawk are species that don't do well in small patches of habitat, even if that habitat would be suitable if it were within a large area of similar habitat parasitism from the Brown headed cowbird, which is a species that invaded over a hundred years ago. But we're still feeling the effects of the decline of the birds whose nests that cow bird lays its eggs in a disease, uh, may be playing an important part in pesticides as well have been approved. Speaker 2: 04:09 Definitely pesticides are a, an important part. And one, uh, important point that was actually not brought out in the article, uh, just published in science was the linkage between bird decline and insect decline because, uh, another study, uh, just published recently suggesting that the biomass of insects decreased 75%. Well, if you've decreased the food supply 75%, it's no surprise that the population of the birds that prey upon the insects, the next step up in the food chain will have decreased by some similar amount. And burrs are critical to overall ecosystems or many people may not realize how critical they are. They serve many important roles from scavengers to pollinators, uh, as, uh, in the hummingbirds, a seed eaters, many environmental roles and uh, how we're researchers able to make this determination to actually put a number on this decline. So it was a very interesting convergence of two methods. Speaker 2: 05:16 One was simply looking at the trends of counts and there's a program called the breeding bird survey where birders a adopt a route where they drive stop every half mile, do account for three minutes while with those spread all over the country. After a while you build up to some significant data. But really I thought the more interesting facet was looking at radar. So if weather, uh, surveying radar is polarized in two directions, they can distinguish between birds and raindrops or snowflakes or other things that's a marketable and distinguished from even. So anyway, they obviously can distinguish between species of bird, but just taking birds in mass. Then that suggested large decline that paralleled that from the actual counts. Now what is the disappearance of 3 billion birds? In North America. Tell us about where we're heading or regarding all the species on the planet. Is this the literal Canary in the coal mine? Speaker 2: 06:22 And that's an awfully good metaphor. You know, the planet needs to sustain a broad spectrum of life if it's going to sustain human life and we still have a very fuzzy idea of all the ecological connections that are out there. And to cast aside the pieces that constitute that network when we still don't understand how it works is really shortsighted. Now that we know the scope of this problem, is there much that can be done to reverse this overall decline in birds? Yes, there's definite possibilities for hope and for reversal. And the article points out that when major group of birds that has actually increased over this time are the waterfowl, the ducks, geese, that inference to manage those, to create habitat for them have paid off. So parallel could be done with other species, with other groups. Now the Cornell university and it's media blitz associated with this press release is recommending seven specific steps. Speaker 2: 07:39 Keep your windows unreflective so birds don't fly into them. Keep your cats and doors. Eliminate lawn, reduce or eliminate pesticides, drink shade, grown coffee. Because many of our migratory birds winter in places where coffee is grown and coffee that's grown under Sade trees offers burdens, habitat, coffee, that's just a monoculture out in the sun, doesn't offer very much. Who would have known. That's amazing. It's quite a big thing now, Sade gung coffee, so check it out. Reduce and eliminate plastic. The plastic pollution in the ocean as well as on land is a serious problem and inform yourself and participate in the kinds of counts that can contribute to this kind of information. Now those seven steps are great, but they're not nearly enough and humanity needs to look seriously at reducing its footprint on the planet with greenhouse gases and just the amount of space and resources each of us consumes to leave enough room for the rest of the functioning ecosystem. I've been speaking with Phillip, unit, bird specialist at the San Diego natural history museum and author of the San Diego County bird Atlas. Thanks very much. Thanks very much for having me.

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In the half-century since 1970, the number of birds in North America has declined by an estimated three billion — that's a 29 percent decrease.
KPBS Midday Edition Segments