By now you know I listen to news radio every morning. A few days ago I heard about the positive identification of the rare hummingbird that has been visiting a feeder in Oak Park, Illinois. Today I finally had some time to visit the Illinois Birders’ Forum and catch up on the details.
Apparently once they managed to trap and band the bird, they got some additional DNA from a tail feather.
On December 14th, DNA analysis revealed the hummer was a FEMALE! That was a surprise since many photos taken by several people with different equipment under different lighting conditions revealed what appeared to be red gorget feathers that are characteristic of a juvenile male. The DNA sample revealed a band on the W chromosome (which only females have) and one on the Z chromosome (which both males and females have). Two bands in a particular area of the chromosome analysis confirmed that this ‘alien’ bird is female. But, we still had to wait to get confirmation of its being either Rufous or Broad-tailed.
Two days later, on December 16th, the final analysis was received. It’s a Rufous Hummingbird, Selasphorus rufus! A female Rufous Hummingbird.
Regarding the confusion caused by the red gorget feathers, an expert from Kentucky weighed in that, “… immature female Rufous will show 2 to 10 red gorget feathers at this time of year while immature male and adult female Rufous should have more than a dozen.” Well it goes to show that we Illinoisans who are up-to-date on how to spot a juvenile male Ruby-throated Hummingbird, by the few red gorget feathers it displays in late summer and early autumn, can’t differentiate a juvenile or adult male or female among the very rarely seen Rufous.
And so, the posts on the Illinois Birders’ Forum turned to the question of accuracy in counting observed birds on one’s life list! It’s an important question of integrity to be sure, especially for those in competition (which apparently some in the forum are) for most different species observed in a year. You didn’t miss The Big Year in a theater near you, did you? 😉
So, the bad news is that Illinois remains without ever having a confirmed visit by a Broad-tailed Hummingbird. The good news is that there is no longer any ambiguity. Thanks to the Chicago Field Museum’s Pritzker Lab offering its expertise, there is no longer a mysterious “Flying Green Alien” among us.