Putative pheromones in urine of rutting male moose (Alces alces): Evolution of honest advertisement?

We tested hypotheses about how olfactory communication was related to matin g behavior in Alaskan moose (Alces alces gigas). Males dig rutting pits whe re they deposit odiferous urine: females are strongly attracted to and ofte n wallow in those pits. Moreover, mating and parturition are highly synchro nized in moose. Consequently, male urine may play an important role in the mating system and in synchronizing reproduction in moose. Urine samples wer e collected from captive moose on the Kenai Peninsula, Alaska. Samples incl uded those from the mating season and from the nonrutting period for two ad ult males, one yearling male, and one male and one female less than 1 year old. After pH adjustment, samples were extracted with methylene chloride to yield three fractions (acidic, neutral, and basic), which were analyzed by gas chromatography-masa, spectrometry. Potential pheromones included unsat urated alcohols and homologs of tetrahydro-6-methyl pyranone and 2-nonen-4- one. We hypothesize that these compounds are related to hypophagia and cata bolism of body reserves by rutting males, and thereby provide an honest adv ertisement of body condition by male moose during the mating season.