When it comes to mating displays, a little persistence can go a long way, at least for the greater sage grouse. In "Hidden Markov Models Reveal Tactical Adjustment of Temporally Clustered Courtship Displays in Response to the Behaviors of a Robotic Female," published in The American Naturalist, Anna C. Perry and her colleagues at the University of California in Davis (USA), the Max Planck Institute in Leipzig (Germany) and the University of Florida (USA) use a custom-built statistical model to understand an under-explored dimension of greater sage grouse mating display behavior. The authors report that males that show greater display persistence, even in the face of seemingly uninterested females, have a competitive advantage over their peers.
The greater sage grouse, a bird native to North America, has an elaborate courtship ritual. Every year, males congregate at locations known as "leks" to perform competitive mating displays to entice females to copulate. Each mating display, in which the male performs a series of ritualized movements and sounds with his air sacs inflated, is referred to as a "strut." These "struts" are typically performed one after another in quick succession, in what is referred to as a "bout." Mating success is highly skewed, with a percentage of birds never once mating and a privileged few mating dozens of times.
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In studies that seek to understand why some individuals are so much more successful than others, researchers have often counted the total number of display events or averaged the lengths of the intervals separating displays within a bout. "These 'bout agnostic' analyses collapse each animal's multidimensional display effort into a single metric, potentially discarding important information," Perry and her coauthors write.
Perry's custom-built hidden Markov model, on the other hand, offered several advantages over simpler models. For one, it accounted for differences in display persistence—characterized by the...
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