A MARTINEZ, HOST:
The heat waves rippling across the Western U.S. are creating problems for wildlife researchers. From member station KPBS, Claire Trageser reports that an annual bighorn sheep count was canceled outside of San Diego after a volunteer died.
CLAIRE TRAGESER, BYLINE: It was supposed to be the fiftieth anniversary of a citizen scientist tradition. Every year, for three days in early July, volunteers hike into the desert, sit in the shade all day and count sheep.
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UNIDENTIFIED PERSON: I've got the male. The male's going down, down, down, down to the water right now.
TRAGESER: That's a video made at last year's count. Volunteers like Callie Mack say their efforts help keep tabs on the Peninsular bighorn sheep, which are endangered.
CALLIE MACK: You hike up there, and you're all hot and sweaty, and you're carrying some gear, and you're saying to each other, oh, why do we do this every year? This is just miserable.
TRAGESER: Mack has been going to the count for 35 years and says it's worth it.
MACK: All of a sudden, you start seeing sheep coming down to get a drink or maybe coming into your count site, and everything changes. It's like the sun coming up.
TRAGESER: But not this year. Right before the scheduled count, a volunteer was out in the 116-degree heat, stashing water for sheep counters to use. He died of heat stroke. The State Parks Department decided to cancel the count. Volunteers like Mack were not happy.
MACK: Honestly, we felt like we'd been slapped hard in the face by State Parks. They might have made some modifications. They could have gathered us all together beforehand and said, look, we don't want this to happen again. Be extra cautious.
TRAGESER: The California State Parks Department wouldn't do an interview about the decision, but here's part of a pre-recorded statement Spokesman Jorge Moreno sent.
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JORGE MORENO: While California State Parks appreciates the citizen science surveys, it should be noted that the dataset is only one piece of the overall bighorn sheep recovery plan.
TRAGESER: He says the extreme heat makes the count just not worth it. And there are other ways to count sheep, including using helicopters, cameras and GPS collars. But researchers at Oregon State University say a combination of all methods, including firsthand observation, is best.
CLINTON EPPS: And I'm speaking quietly because we're watching a group of bighorn sheep.
TRAGESER: Professor Clinton Epps monitors bighorn sheep populations by checking for parasites in their droppings.
EPPS: OK, we've been here about 20 minutes, and a collared ewe did just drop pellets, so I'm going to go collect the samples and then move on and try to find a different group of sheep.
TRAGESER: He says an annual census done in the same way every year is also important.
EPPS: That's a long dataset, and we don't have many long datasets in this business like that.
TRAGESER: And that dataset helps researchers like him know whether conservation efforts are working. He says cameras and collars also help, as long as you have someone to review all the footage.
EPPS: It's expensive, and it's hard. And, you know, it's one thing to put out cameras. It's another to sit there and review hundreds, maybe thousands of hours worth of videos or thousands of gigabytes worth of photos.
TRAGESER: Epps says in-person counting can also spot issues like disease. But that won't be happening this year. The State Parks Department says they'll work on safety plans, so the count may return in the future. If it doesn't, volunteer Callie Mack says more will be lost than just a sheep census.
MACK: It makes more ordinary citizens aware of why the bighorn needs protection.
TRAGESER: At last count, there were less than 800 Peninsular bighorn sheep. For NPR News, I'm Claire Trageser in San Diego.
(SOUNDBITE OF SPIRO'S "LEVEL 2 SMALL BATS") Transcript provided by NPR, Copyright NPR.