Thursday May 16, 2013.  205 new birds of 43 species (21 species of warbler), 10 recaps. New species:  Red-breasted Nuthatch, Baltimore Oriole, and Pine Siskin. What a difference a day (or a week) makes.  Last Thursday, we banded 11 birds . . . today we banded 205. Yesterday we banded 18 Lincoln’s Sparrows . . . today we banded none. Yesterday we banded 9 Gray Catbirds . . . today we banded 48. Despite the incredible variety today, there were several species that were “missing” from our list which we could well have gotten (and which we DID get yesterday): Blue-headed Vireo, Red-eyed Vireo, Blue Jay, Lincoln’s Sparrow, Swamp Sparrow, and Song Sparrow come to mind among others.

The morning started bright and clear, and we opened our nets with high expectations. They were fulfilled a half hour later, when our first net check yielded enough birds for all. The Bander Training Class had been practicing net-picking for three days, but this was their first glimpse of what a truly busy day looks like. The Catbirds (which normally are not a bander’s favorite) were a welcome addition this morning as they were the perfect “practice” birds for our BTC students, who learned to band today. The BTC was kept busy outside as they manned the nets and banded larger birds (including three Baltimore Orioles, one Cardinal and one Grosbeak . . . not bad for beginners!) while the regular staff banded the smaller birds inside the lab.

I was interested today by two birds with somewhat unusual plumage. The first bird below is a female Black-throated Blue Warbler, with easily the largest wing-check I have ever seen. It measured 11mm from the end of the primary coverts to the end of the white, which not only exceeds the range given for females in Peter Pyle’s guide, it is at the upper end of the range for males as well. Furthermore, you can see that she has more than just a hint of blue – she has a strong blue tint to her head, wing coverts and primaries, and rectrices. Although we can only age her as an after-second year bird, we speculated that she might well be a “senior citizen.”

After-second year female Black-throated Blue Warbler

After-second year female Black-throated Blue Warbler

The second bird with unusual plumage was an after-second year male American Redstart. He slipped from my fingers before I could get a complete set of photos, but I did get the key photo below, which shows his oddly colored tail.

Male American Redstart with a tri-colored tail!

Male American Redstart with a tri-colored tail!

The bird was clearly an older male based on the rest of his plumage – he was black and brilliant orange in all the right places. The sole exception was one half of his tail, which was colored the pale washed out orange of a younger male. I’m not certain all the factors that could account for this effect. However, when Peter Pyle was here he talked about how the hormones that regulate pigment production and deposition can be “turned on” at different times, and that sometimes feathers grow in before the hormones are “on”, resulting in plumage that is more characteristic of a younger bird. However, since the rectrices should grow in symmetrically, that doesn’t account for why half the tail is one color and the other half another. It might be that the bird lost part of its tail, and the replacement feathers grew in while the hormones were  in the “off” position. However, I’m not sure whether the hormones get switched on seasonally, or if they get switched on at some point in the life cycle and then stay on forever. I am open to suggestions!

Many many thanks especially to Gayle and Mike who kept the net-pickers on track, and to Pat L and Pat M who did their “regular” BBBO jobs with calm heads and quick fingers.  Andrea Patterson