After finding a scat of a Pacific fisher (an endangered relative of 

 weasels), Mocha watches her handler check its freshness. The 

 author's team collected some 700 Pacific-fisher scats in northern 

 California after a decline in live-trap catches suggested the popula- 

 tion might be crashing; back in the laboratory, trained dogs will help 

 determine the number of individuals represented in the collection. 



My team compared results from the dogs with data trom 

 hair-snag stations and radio-collared bears, gathered 

 independently by other researchers. Many biologists 

 were skeptical that the dogs would measure up, but we 

 proved otherwise. 



DNA testing of scat samples showed that the dogs detected 

 four times more individual grizzly bears per square mile 

 than the hair-snag stations did. Statistical tests confirmed 

 that sampling by the dogs was unbiased — all bears in the 

 population had an equal probability of being detected. 

 Radio telemetry provided massive amounts of data on the 

 movements of nineteen collared bears during each of the 

 study's three years. In the end it showed the same bear dis- 

 tributions as the scat, but at more than thirty-three times the 

 cost (about $1 million for telemetry versus $30,000 for the 

 dog sampling). Moreover, two grizzly bears died and one 

 was seriously injured as a result of the trapping — high stakes 

 for a population of only a hundred threatened animals. 



Today — many projects later — my program is studying 

 numerous species across the United States, Canada, and 

 Brazil. Perhaps the most challenging of those projects is 

 in northeastern Alberta. The province has tremendous 

 oil reserves trapped in tar sands, which require a special, 

 expensive extraction process. The resulting environmental 

 disturbance is hard to exaggerate. Even before extraction 

 begins, during exploration for tar-sands deposits, new roads 

 carve up pristine wilderness, small trailer cities spring 



up to accommodate hundreds of workers, and immense 

 equipment appears, some airlifted in by helicopter [see 

 photograph on next page]. Machines that produce enormous 

 vibrations search out ideal spots for oil wells. 



One of the first corporations to begin working in the area, 

 in collaboration with the native Chipewyan Dene tribe, 

 asked us to monitor the long-term effects of its activities 

 on caribou, moose, and wolves; caribou are threatened in 

 all of Canada and are declining even more dramatically in 

 Alberta. In 2006, the company began exploring — the prelude 

 to a decade of planned extraction — at its 430-square-mile 

 lease site, and we began monitoring a 1,000-square-mile 

 area that includes that site and others. 



Both the exploration activities and our surveys are restricted 

 to winter, when the spongy, boglike habitat, called "muskeg," 

 freezes; come spring, everyone disappears, and all is quiet 

 until the following winter. Mason, a lanky three-year-old 

 black Labrador retriever, is one of four dogs that have so 

 far braved two Alberta winters on the project. Each winter 

 morning before dawn, Mason's handler would suit him up 

 in a fleece safety vest and boots, and they'd head out into 

 the cold. Mason and the other dogs found more than 2,500 

 scats throughout the huge study site during the winters of 

 2006 and 2007. They had no trouble finding scat that was 

 hidden beneath two or more feet of snow, and sometimes 

 so frozen the handlers had to chisel it free. 



Judging by the fluctuations of hormones in the scat over 

 time, tar-sands exploration seems to be having physiological 

 effects on all three species. In general, the hormone Cortisol 

 increases (reflecting mounting emotional or nutritional 

 stress, or both) and thyroid hormone decreases (reflecting 

 mounting nutritional stress) in scat as exploration activity 

 gears up and peaks. Intriguingly, the moose and caribou 

 appear to recover as soon as the work crews start packing 

 up to go home, but still well before spring arrives — so 

 it's not the renewal of food supplies that alleviate the 

 animals' stresses. Not so for the wolves: their nutritional 

 and emotional stress levels increase right through the end 

 of the season, suggesting that the disturbance makes it 

 progressively more difficult for them to catch prey. 



Development also seems to be changing the animals' 

 habitat use. The scat's location shows that wolves and caribou 

 have developed a preference for the new artificial linear 

 features crisscrossing their habitat: roads, "outlines" cleared 

 for seismic mapping ot tar-sands deposits, and paths above 

 underground pipelines. Wolves had the strongest preference, 

 followed by caribou — raising concern that attraction to 

 the exposed areas could be making caribou more vulner- 

 able to predation by wolves. Moose, by contrast, preferred 

 good feeding grounds over linear features, a strategy that 

 served them well: hormones in their scat showed smaller 

 nutritional deficits than in the other two species. 



Since 2006, the number of oil leases issued in the area has 

 skyrocketed. Only time will tell how the animals w ill bear 

 the mounting disturbance, particularly once year-round 



October 2008 natural history 



5 1 



