Researcher Wolfgang Goymann and colleagues were studying the migrations of the garden warblers (Sylvia borin) when they discovered an interesting nugget of information:
While pockets of flab accumulated over the winter months may be a source of frustration for some, it can be a cause of joy for others …The researchers fitted ten fat birds and ten lean birds on the Italian island of Ventotene with temporary adhesive radio transmitters. [...]
Monitoring their test subjects using the stick-on surveillance bugs, the German boffins found that the more rotund ones had sex sooner and generally slept only one night in any given location. Plumpness led to sexual success for the wobblebottomed group, while their spindly counterparts took longer to get any action – and tended to make longer stays of more than one night, too.