Just keep on talking, and you might snag the female of your dreams—if you're a panda that is. Male giant pandas bleat during the mating season, and some bleat longer than others. To find out if longer bleats signaled more aggressive males, researchers looked for various hormones in the male's feces. (It's easier than drawing blood.) Sure enough, males who bleated longer sported higher levels of testosterone and other "male" sex hormones than those with shorter bleats, the team reports  online tomorrow in Biology Letters. Females gravitate towards the long bleaters, probably because their aggressiveness makes them better providers. Male pandas may also listen in to avoid getting into a fight with another male out of their league.
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