March 30, 2009

Global Amphibian Declines - The Movie

During the past year filmmaker Allison Argo and her team have been traveling around the world to film declining amphibians and find out from scientists what can being done about it. In addition to filming in Panama and the southeastern U.S., Allison's team also spent a few days with my research group while we conducted research on Sierra Nevada yellow-legged frogs in Yosemite National Park. The resulting film, "Frogs: The Thin Green Line" will be shown for the first time on April 5 (this Sunday) on PBS. Allison's previous films on amphibian declines (The Last Frog), declining shorebirds (Crash: A Tale of Two Species), and other wildlife-related topics were extraordinarily good, so I suspect that this latest film will be well worth watching. Hopefully Allison didn't include the footage of me falling into the pond.... On 3/31,the film's creators posted a podcast from "behind the scenes". Check it out.

If you do watch the film, feel free to post your reviews and thoughts here.

Now to the task of finding a friend who owns a TV....

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March 23, 2009

New National Geographic Story on Amphibian Declines

Writer Jennifer Holland and photographer Joel Sartore have created a masterful story on the global amphibian decline phenomenon, just published in National Geographic magazine. The situation surrounding the mountain yellow-legged frog is described in the story, and Joel's photographs of live and dead Rana muscosa from Sixty Lake Basin bring this animal's plight into a sad focus. Check it out.

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March 16, 2009

Anybody Have a Spare Pond?

The ongoing severe declines of mountain yellow-legged frogs in the Sierra Nevada make it all but inevitable that these populations will eventually be listed under the federal Endangered Species Act. Such a listing will trigger the writing of recovery plans for Rana sierrae and Rana muscosa, plans that will undoubtedly call for the development of captive breeding programs. If successful such programs could provide frogs for reintroductions back into the wild and for experiments that are critical to our understanding of important issues related to frog conservation.

As I've discussed in previous posts captive breeding has an increasingly important role to play in species conservation programs but because maintaining frogs in artificial environments (e.g., indoor aquaria in zoos) is very labor intensive (think of the time required to feed 100 frogs every day, change their water, and clean their enclosures), this gets expensive in a hurry. A cheaper and potentially more productive route would be to hold frogs in natural or semi-natural ponds outdoors. This would greatly reduce the resources needed to maintain these populations because the frogs could feed themselves. All we need are some ponds that would provide suitable habitat for mountain yellow-legged frogs. Ideal ponds would be located at elevations above 6000', be deep enough to allow frogs to overwinter (>10 feet), and have reasonable access. Ponds would also need to be surrounded with a frog-proof barrier to ensure that frogs don't wander off.

If we can't locate such ponds we need to consider constructing them. As I write this I'm staring out the window at my back yard, wondering if maybe we could replace that useless lawn with a frog pond. But seriously, we need to engage any interested agency or member of the public and provide the resources necessary to make this happen. Might there be a national forest ranger district out there with a pond near a district office that could be turned into a frog pond? Are there any private landowners who might be willing to have one of their ponds put to such a use?

If any of you readers have any ideas I'd love to hear them.

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March 10, 2009

One Fewer Frog in the Forest

Research by Karen Lips and others on amphibian declines in Central America has made clear that the scope of these declines is unprecedented in modern times. In recent years dozens and perhaps hundreds of Central American amphibian species are thought to have been driven to extinction by the amphibian chytrid fungus. The following article provides a glimpse at one of those amphibians, the Panamanian golden frog. This species is a national icon in Panama but is now believed to be extinct in the wild (link). The only individuals still in existence are those housed in a captive breeding facility in Central America. For additional information about this iconic species, check out

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March 3, 2009

Once Upon a Time....

I remember with crystal clarity the day I realized the impact that the amphibian chytrid fungus (Batrachochytrium dendrobatidis - Bd) was having on mountain yellow-legged frogs in the Sierra Nevada. It was July 2000 and my field crew and I were surveying lakes and ponds along the Monarch Divide and Cirque Crest for amphibians and fish. I'd been as excited as a little kid to get into this area and see some of the most remote lakes in the Sierra, places where several years earlier a backcountry ranger had made observations of many mountain yellow-legged frog populations. When the trip was over 20 days later I felt like I'd been hit over the head with a hammer. The future of frog restoration in the Sierra Nevada had just gotten a lot more complicated than I ever imagined it would be.

Up until that trip the available data on Bd and its impacts was still sparse and remained an abstraction to me. The observations made by Dave Bradford 20 years earlier of frog die-offs in western Sequoia National Park were worrisome but were surrounded by enough uncertainty regarding the cause that I wasn't paying those observations much attention. Afterall, for the past five years I'd surveyed hundreds of lakes and the effects of fish were as clearcut as could be. But there were a few lakes that I'd run across during all of those surveys that did give me pause. There were those lakes near Pavilion Dome that contained fabulous frog habitat but in which I found either no frogs or only the decaying carcasses of frogs that had died the previous winter. And that lake between Lake Basin and Dumbbell Basin where I'd seen lots of frogs during a backpack trip in the early 1990s but by the time we surveyed that site there wasn't a frog to be found. These observations nagged at me but still lacked any broader context. In contrast, my recent analyses of survey data from more than 2000 lakes had clearly shown the negative effect of fish on frogs, and early results from two fish removal experiments conducted by me and by Vance Vredenburg showed dramatic increases in the frog populations at these sites just a few years after fish removal. Restoration of frog populations wasn't going to be easy because fish were so ubiquitous but at least we had the tools to reverse the decline of the mountain yellow-legged frog. To my eyes, the future looked bright.

The first lake I surveyed on that Monarch Divide trip was at the head of the Gorge of Despair. Looking down on the lake from above I could only smile. There should be gobs of tadpoles in that warm cove on the north side of the lake, I thought, and adult frogs will be sunning by the hundreds on those granite slabs near the outlet. An hour later I had finished the survey and could only shake my head. I'd found only four mountain yellow-legged frog tadpoles and had not seen a single adult. Even more alarming was that the tadpoles were clearly sick. We didn't have an accurate method of detecting Bd in those days but my notes on the datasheet that I filled out that day had an ominous tone: "All four tadpoles were large (~3 years old). The one individual I was able to catch had only a partial beak and no toothrows. Skin had a mottled appearance. Chytrid fungus?". Every subsequent day produced similar observations. In lake after lake where frogs had been abundant just a few years earlier we found either no mountain yellow-legged frogs or only a few tadpoles, all with mouthpart deformities suggestive of Bd infection.

Twenty days later, surveys completed and out of food, we hiked down the Copper Creek trail to Cedar Grove. On that long hot descent I struggled to put all of the pieces together. Frog die-offs in western Sequoia National Park in the 1970s and 1980s, healthy frog populations throughout the eastern portions of Sequoia and Kings Canyon National Parks, and now evidence of recent and ongoing die-offs along the Monarch Divide and Cirque Crest.... Could it be that Bd had been spreading from west to east across this part of the Sierra Nevada since the 1970s and that even those huge frog populations in places like Barrett Lakes Basin and Sixty Lake Basin might someday also succumb to this plague? The thought sent shivers down my spine and haunted me for years.

I called Dave Bradford the next day and before I could describe to him what we'd seen on our trip I somewhat immodestly blurted out, "I know what wiped out your frogs on the Tablelands - the chytrid fungus!". I don't know what he thought of my remark or the subsequent description of lake after lake with hardly a frog to be found, but I had seen the future of the mountain yellow-legged frog and it filled me with a profound sense of dread. All that I knew was about to change and the frogs that to me had become as much a part of the Sierra Nevada as the towering granite peaks were soon to be pushed aside by an unseen and unstoppable force.

And so it has come to be. Many of the lake basins where I counted thousands of frogs in the late 1990s are now frogless.
When I walk along a lake shoreline no frogs jump into the water from their grassy hiding places. The shallows where tadpoles used to congregate by the thousands on warm afternoons, thrashing frantically in their retreat to deeper water when I approached, are calm and placid now. The mayflies and beetles are still in abundance in the nearshore waters and on the surface the lakes are as beautiful as ever, but these lakes are profoundly changed, perhaps forever. The same could be said of that idealistic young biologist....

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