The Birds Across the Bay

You may not have heard me mention the white-crowned sparrows of the East San Francisco Bay much because, well, there aren't that many. At least not the year-round Nuttall's white-crowned sparrow residents.

Subspecies Review

Remember the three subspecies we get here on the California coast? There's the Puget Sound white-crowned sparrow (PSWS or lovingly, "piss wiss"), the Gambel's white-crowned sparrow (GWCS) with its "candy-corn orange" beak, and of course, my focal subspecies, the Nuttall's white-crowned sparrow (NWCS). The Gambel's are easy to tell apart from the others because of their Crayola-colored beak. The Puget Sound and the Nuttall's are a little more tricky though. Both have black streaks on their upper beak extending from the base to the tip of the nares, as seen in the picture below.

(Really just an excuse to show my favorite of Pete's photos) 

Not seen in the picture below but also a distinguishing characteristic of the PSWS and the NWCS are the yellow wash to the feathers in underside of their wings (in the "shoulder" area if you will.) According to Peter Pyle and his banding bible, Identification Guide to North American Birds: Part I, the only way to confidently tell the difference between a Puget Sound and a Nuttell's is by an equation that is of course escaping me at the moment but it is something like the wing length divided by the lean weight (weight in grams minus the fat score) and if that result is less than 2.3 (ish) then it's a Nuttell's and if it's greater than 2.3 (ish) then it's a Puget Sound.* Nuts right? 

*I'll come back to this post and put in the real equation when I am reunited with my version of the Identification Guide, which banders just call "Pyle." As in, "Have you seen my copy of Pyle?" or "Lame, this bird just pooped all over my Pyle."**

**UPDATE 10/25/15

Here's a photograph of part of the page from Pyle.

The equation is: wing ÷ lean weight where lean weight is the weight minus the fat score
If it's >2.6 you've got yourself a PSWS
If it's ≤ 2.6 you're holding a NWCS 

The songs of all three subspecies are different as well but the biggest behavioral difference is that the Nuttall's white-crowns like to stay put. They are the only non-migratory subspecies and are year-round residents of the Bay Area. 

White-crowned Sparrows of the East Bay 

When I was originally planning out my project I was going to band all over the San Francisco Bay in every public park I could. This plan got toned down a bit when I started asking local birders where I could find Nuttall's white-crowns in the East Bay.

Turns out that to the East of this beautiful Bay Bridge here, there aren't too many resident Nuttall's. There was an odd mysticism surrounding these sparrows whenever I would ask about them. I would get answers like, "I heard there were a few of them down in Oakland." or "I thought I heard one singing the other day in the Emeryville Home Depot parking lot." After inquiring among birders and taking a few scoping birdwatching hikes myself in among the East Bay Regional Parks I was able to find only two tiny populations at Eastshore State Park and Albany Bulb. 

Of these two sites I only ever did any banding at Eastshore because at the time Albany Bulb was home to a massive homeless encampment and while there were many wonderful birds and art pieces there I did not feel so safe arriving alone in the pre-dawn hours of the morning. [The encampment has since been removed and the city is working on what is being called "The Albany Bulb Transition" - you can read all about it here.]

I didn't have much luck over at Eastshore either. The habitat is brushy and low and the nets are just too exposed for any sensible bird to fly into. At the time of my attempts the weather was also incredibly temperamental and I got caught in the pouring rain. 

I did manage to catch two males there though before I got rained out: KRW/S and OS/GB. These two males ended up being quite special. Of all the birds I caught over this two-year study period (103 individuals) only 5 were infected with avian malaria. This is fantastic news for the birds, terrible news for my study. There is just no way to make any solid statistical conclusions with an infection rate of 4.9%. But these two wayward birds holding it down as some of the sole white-crowned sparrow residents of the East Bay were BOTH infected. That means they accounted for 40% of the infected birds in my study.

Don't Stop Believin'

A testament to the toughness of these Easterly birds. Not only are they in the minority and isolated from their fellow subspecies flock, they are also battling intracellular blood parasites that are reproducing and rupturing their red blood cells. But do you think all of that could keep them down? 

Not a chance. 

I just got this email and photo from birder John Kenny of OS/GB alive and well!

It thrills me to see him alive and I want to extend a thank you to him for harboring so resiliently the parasite DNA that served as many a positive control in so many otherwise frustrating lab studies where sample after sample turned up negative.