The article on “Carry-over effects from breeding modulate the annual cycle of a long distance migrant: An experimental demonstration” by Paulo Catry and his fellow researchers covers a facet of the life history of the Cory Shearwater.  It was published in the journal Ecology Vol. 94, No. 6, pp. 1230-1235. The facet of the migratory bird’s life history that the researchers examined is the effect of a failed breeding season upon the migratory birds, specifically their behavior, survival, and their subsequent geographic distribution. Paulo and his A team gathered data on this by removing the fledgling chick from the nest and banding the birds, thus synthesizing an unsuccessful breeding season in 2009. The A team then proceeded to band several pairs of successful adult shearwaters in 2009 to function as a control.  In
2010 the A team allowed the manipulated nesting pairs from 2009 to breed successfully to root out any unsavory concerns. The A team than simply placed the data upon a map, each bird supplying one data point, except the birds which were manipulated, which served as two in their successful and unsuccessful years. The A team toiled day in and day out to discover the hidden changes in behavior and geographic distribution between the successful and unsuccessful breeders. Well it didn’t take much toiling the data spoke for itself and a surprising 4/7 of the breeders which were unsuccessful chose to stay in the Canary channel rather than to proceed with the rest of the flock further south to the wintering grounds compared to the successful pairs of which 0/14 chose to stay.  The ever hopeful Cory’s Shearwaters that were manipulated/unsuccessful in their breeding season spent their time pampering themselves, molting early, and making sure they were in prime mating condition for the next breeding season in which they will surely excel. But perhaps the biggest finding of all was the fact that these unsuccessful pairs arrived to breeding grounds earlier than did the successful pairs, or their successful selves in the latter year. This is a great boon to their chances of passing on their genetics since many times a good territory is a source of great competition.