Petaluma, Kqed., Seventy Four Degrees discussed on Science Friday


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M. dot com and by the listeners of KQED. sunny skies today temperatures ranging from the mid seventies at the coast to the upper eighties inland currently the temperature in Petaluma is eighty two in San Jose at seventy six and at SFO right now it's seventy four degrees. this is science Friday I'm IRA Plato we've heard about steep declines in the populations of certain species for instance just this February reports of a drop in insect populations world wine now another possible warning sign of global environment in crisis report in the journal science this week says that north American bird populations have declined by nearly three billion mess with it be three billion birds since nineteen seventy that's a loss of nearly one in four birds what is the cars and how do you count that kind of population decline Ken Rosenberg is one of the authors of that report and on the plight conservation scientist at the famous Cornell lab of ornithology in Ithaca welcome back to science Friday. thanks IRA that's a lot of birds isn't it. it is a lot of birds there a lot of birds out there but we're we've been seeing this steady decline and people who love birds in our after every day I've been noticing fewer and fewer birds and now we can put some hard numbers on those declines but there's still a lot of birds left right this is not a we're not talking about extinction here we're not and this is different from from other studies that are showing in and of course there are birds that are dropping towards extinction but what we're seeing here is like a whole nother level of biodiversity loss because we're seeing the loss of abundance among among common species of birds so it's not just the rare and threatened species but what we're finding is this pervasive loss among common familiar everyday for giving me an idea of what we're talking about what kind of birds. well some of the biggest losses are in grassland birds birds like meadow larks and horned lark Savannah sparrows but not only the specialist species one of the big surprising results is that other birds that are found out and farmland rural landscapes across America like red wing blackbirds are also in steep decline so what that's telling us is that habitat loss is so pervasive in that these environments are just not able to support basic bird life we have had birds go extinct them and and speaking specifically about the famous passenger pigeon right. that's right and we make an. we make an analogy in the paper one of our crofters had done this fascinating study where she was able to bring in whatever date existed from the passenger pigeon from the eighteen hundreds and essentially create a model of what the decline of the passenger pigeon might have looked like before it went extinct and that the climb looked a lot like what we're seeing today in these other common birds and nobody ever thought the passenger pigeon we've got extinct it was the most abundant bird that that ever lived on the continent but these declines look very similar and what it's telling us is that if we were if we have been monitoring bird's back at that time and people are paying attention and we are at that thirty percent loss point let's say it's very likely that we would have been able to prevent that extinction and do something about it and and is that the same case now can we prevent any loss of birds. well we might not be able to save everything but but that is what gives us hope and we have we have examples of birds more recently that we have recovered and and that we have brought back the bald eagle the peregrine falcon in those cases we knew what the problem was in it when we were able to ban DDT the harmful pesticide and pass laws that stop shooting of hawks and eagles these populations rebounded pretty quickly so we know birds can be resilient we know that they will respond positively to our actions if we do it but don't we have to know why they died off to begin with. that's true and we maybe got lucky in a sense with with the bald eagle because DDT was such an obvious factor and since these losses were seeing now are so pervasive they really across every single habitat then obviously multiple factors are at work and it's very complex and it's not it's not a simple thing but we do know in a lot of cases what what the major factors are in habitat loss and we know a lot of the things that are killing birds such as collisions with windows and buildings and predation by outdoor cats and these are things that we can do something about and we can minimize those bird deaths at the same time that we're working to protect and restore habitat isn't a changing climate have anything to do with this thing. well that's a good question this week of course and we thought about that a lot and climate change is obviously having an effect and it's probably going to be having more of an effect as we move forward but climate change is not the driver of these big declines it is habitat loss and so in a sense the habitat loss the issue is is it's right in front of us there's so much urgency there and for not protecting. restoring habitats and if there isn't enough habitat for these birds to survive in and move and not just birds other other wildlife to move into as climate change does whatever it's going to do on the landscape plan then it won't matter very much so we can't just focus on climate change into the future we have to make sure we're protecting these populations right now someone let me get a bit into the methodology this is fascinating to me hope to my ears so how do you know how do you count the bird populations. well we we we relied on two very independent sources of data and one of them were fairly simple counts that that have gone back fifty years or more that are done by bird watchers and we have because so many people love birds and can identify them we have this fantastic collaboration between the scientists and the amateur bird watchers were the scientists can design these surveys that are quite rigorous but they have bird watchers are the eyes and the ears out there scientists cannot collect this kind of data themselves so we have thousands of people out there collecting the data and then giving it back to the scientists who can then do these analyses and so we're very lucky to have this fifty year monitoring data set on bird populations we don't have anything like that for any other group of organisms but then the the weather radar data was a completely different source it doesn't rely on human observations and radar can see the migration that's happening in the sky and since most birds are actually migrating at night the radars picking up these bird migrations at night if you if you could even even see this on the weather channel if you see a big storm coming on when they show the radar that clutter that you see out behind the storm those are birds usually now so the weather the weather people filter that out but ornithologists have taken advantage of it and it's really only recently because we need super computers really to look at that at that scale hundred forty three of these NEXRAD weather radar stations and we're able to piece that together and look at the total mass of migration that's passing over the United States over the entire spring migration and we went back in to get back in time with that kind of data we're able to go back only eleven years but we saw a fourteen percent decline in the mass of migration passing over the United States and just an eleven year period. and that's about the same order of magnitude that we were seeing from the surveys so these two very independent sources of data error essentially telling us there's this major loss and that gives us a lot more confidence that the result is real do you have any confidence that the folks like us you know.

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