After having a great opportunity to study an adult Gambel’s White-crowned Sparrow (Zonotrichia leucophrys gambelii) at Arlene Koch’s property last weekend near Easton, while also enjoying the immature Harris’s Sparrow there, I was interested to learn more about this western subspecies’ history in Pennsylvania and the mid-Atlantic. Gambel’s White-crowneds are essentially the western-Canadian counterpart of our more familiar Eastern birds (Z. l. leucophrys). Distinguishing between any of the five subspecies of White-crowned Sparrows can be difficult, sometimes impossible. The Mountain White-crowned Sparrow (Z. l. oriantha) and Eastern are the most similar subspecies – both having the ‘classic’ White-crowned Sparrow black-and-white streaked head, black lores, and pinkish bill. The Gambel’s is similar to Mountain and Eastern in most respects, but never shows black lores and has a more orange bill color. For a much more detailed discussion on the differences between these three subspecies, please visit David Sibley’s incredibly informative article at this link. Sibley also has a very useful article concerning the range of Gambel’s and Eastern at this link.
On Wednesday, February 4th, I had some free time to run down to Newville in Cumberland County, PA and try to find the other Harris’s Sparrow overwintering in the state this year along the Big Spring. Vern Gauthier found this adult Harris’s; the second he has found near Newville. Stray Harris’s Sparrows are often in the company of White-crowned Sparrows, so when I arrived at the site yesterday I wasn’t too surprised to immediately find 13 White-crowned Sparrows lurking in the roadside brush. I was surprised, however, to have the very first bird I viewed in my binos to be lacking black lores and have an orange bill! Another Gambel’s with another Harris’s Sparrow! I have always tried to keep an eye out for ‘different’ looking White-crowneds whenever I see a group of them while out birding, but I’ve never knowingly come across any out-of-range subspecies before. This pale-lored bird looked pretty good to me though, so I kept taking photos and tried to get some similar shots of the adult Easterns it was with.
Keeping track of subspecies can be a fun way to add to your birding experiences, and can also liven up a ‘slow’ day of birding your local patch. Not to mention what we can learn as birders and biologist from determining the status and movements of various subspecies across their ranges. Disciphering between these two subspecies is difficult and requires getting very clear looks at each White-crowned Sparrow you come across, but that just adds to the fun. Currently there are less than 20 formal reports of Gambel’s White-crowned Sparrow in Pennsylvania. Most sightings have coincided with Eastern White-crowned Sparrows main migration period through the state, between April and May, where they are considered fairly regular at locations like Presque Isle SP along the shores of Lake Erie. Gambel’s have also turned up, rarely, among wintering flocks of Eastern White-crowneds between November and March. Most of the winter reports come from southeastern PA, where White-crowned Sparrows are more common during winter to begin with. Intermediate type birds have also been encountered, which adds to the challenge of separating the two subspecies, so obtaining photographs of these birds would be incredibly useful.
Adult Gambel’s are much easier to spot among adult Easterns than the immatures are. Currently very little is documented concerning the immature plumage of these two, and there may be so much variation that it’s impossible to tell with certainty. For example, I also spotted the very plain-lored immature bird shown below in the same flock as the adult discussed above. As with the adults, immature Easterns are thought to have dirtier lores with a particularly smudgy area right in front of the bird’s eyes as well as the larger, pinker bill color. Immature Gambel’s have completely plain gray lores and a smaller, orange bill. The immature shown below certainly seems to have very plain lores and an orange bill. However, taking a look back through my photo library of immature White-crowned Sparrows from Pennsylvania, I’m having a very difficult time coming to a conclusion with this bird based solely off of the lores. Take a look at the second immature bird below, photographed in January 2014 in Centre County – is this also a Gambel’s?
By keeping an eye out for different and unusual White-crowned Sparrows while you are out birding, as well as documenting them and adding photos to your eBird checklists, we could really learn a lot more about the appearance of these two similar subspecies as well as determining just how many Gambel’s might truly be here in Pennsylvania and the mid-Atlantic. If you are looking for something to do this weekend, why not try to photograph your local White-crowned Sparrows and let me know in the comments of this article what you turn up!