From The Experience Magazine – Spring 2007
Biology research project investigates the mating habits of American Kestrels
According to Biology Professor Dr. Ted Whitehead, there’s a dirty little secret about birds. Despite the classic image of a pair of monogamous parents doting over a nest of chicks, the truth is, there’s a lot of messing around going on.
“People have this preconceived notion that birds are monogamous and that mommy and daddy raise their chicks together like one happy family,” said Whitehead. “The more we study birds, the more we see that’s not the case.”
Better genes or help at home?
For three years, Whitehead and fellow Biology professor Dr. Brad Tripp have been investigating evidence of monogamy among mating pairs of American Kestrels, the smallest falcons in North America. As with other raptors – such as hawks, eagles and owls – it takes two adult kestrels to raise a brood of chicks.
However, Dr. Whitehead and Dr. Tripp are looking to see if kestrels’ monogamy is genetic or social. If it’s genetic, the two adults mate solely with themselves. If it’s social, the female will pair up with one male to help her with the nest, but then sneak off to have trysts with other males in order to find superior genetic material for her offspring. Such behavior is not without risk. If the nest mate discovers the infidelity, he will likely abandon the nest, guaranteeing the demise of the chicks.
Better genes or dependable help back home? What’s a mother to do when the propagation of the species is at stake?
“If any of the raptors are likely to be socially monogamous, it would be kestrels because there are so many of them,” said Dr. Tripp. “It has to do with the genetic continuity of the species and mate selection. The big question is have [kestrels] been forced down this monogamy road for this reason.”
In 2003, Tripp and Whitehead – with the help of student and faculty volunteers – built fourteen nest boxes that they later hung inside the Ridgefield National Wildlife Refuge, near Ridgefield, Wash. They found no live birds in 2004, but gathered data from four nests in 2005. Last spring, they found another three active nests. With the help of Biology major Eric Alston, Tripp and Whitehead took tiny blood samples from twelve birds in all.
“They have little veins, which always makes blood draws interesting,” Whitehead said. “And they have sharp talons and beaks that they like to use to reach out and grab you. Because the chicks aren’t real active, grow rapidly and get lots of parental care, they actually weigh more than the parents.”
DNA doesn’t lie
Back on campus, Alston and classmate Tameka Smith purified the blood samples, extracted and copied regions of DNA using PCR (polymerase chain reaction) techniques, and then ran samples through electrophoresis gels in order to analyze the genetic coding.
And the verdict? Three faithful couples.
“All three families were genetically related,” said Alston, a native of Medford, Ore. “Since they appear to be genetically monogamous, there [seems to be] no advantage to cheating…But we need to get more samples to have any real definitive results.”