Only mature bulls produce the aromatic urine. And they do most of the breeding. Wildlife managers want to make sure there are enough older bulls to impregnate the available cows. If a bull misses a cow in estrus, he gets a second chance a month later. But, according to Kris Hundertmark, senior scientist at the center, that means the calf will be born later the next spring, giving it less time to gain strength for its punishing first winter.
Biologists think dwindling daylight is what brings moose together in the fall.
Whittle was the first to study the chemical components of moose urine, during a six-month internship at Monell Chemical Senses Center in Philadelphia. It's great to apply chemistry to a living system, to see how it works,'' she said. Whittle is trying to solve the riddle of moose pheromones by process of elimination. She blended the two dominant components of bull urine, an alcohol and a phenol, into a ''cocktail'' and placed a sponge soaked in the mixture beneath the cows' rubbery snouts. It had no effect.