In preparation for starting WVWA’s MAPS station this season, I took a trip out west (that is, to the western part of PA… not the wild west of magical western birds) to visit Powdermill Avian Research Center (PARC) and participate in their Advanced Bird Banding Workshop. PARC is the Carnegie Museum of Natural History’s biological field station at Powdermill Nature Reserve, and is the oldest running bird banding station in North America. I was really fortunate to work there for about 6 months as a technician, and it is truly a great place, with immensely knowledgeable and awesome people. And needless to say, the birds there are pretty great, too. WVWA is partnering with PARC in order to operate our MAPS station, and their help and guidance have already been immeasurable.
I can’t even tell you how much.
But anyway, PARC holds their five-day Advanced Bird Banding Workshop every year during spring migration, and bird banders from across the country come for the chance to intensively learn from the experts (or as I like to call them, the Bird Whisperers) about the intricacies of aging and sexing songbirds using subtle molt limits and differences in plumage (and believe me, intricacies they most certainly are). Over the course of the workshop, I learned what to look for on each bird and where, to correctly age and sex many species – including those that might be caught at the MAPS station this season.
Not only did I have an amazing and instructive time (to say the least) at Powdermill, but I also had the chance to visit another migratory banding station, this one run by Audubon Pennsylvania at Presque Isle State Park, right on Lake Erie. A good friend of mine (and another ex-Powdermill tech) is the bander there this spring, and checking out her banding operation gave me some great ideas for running the MAPS station at Crossways (like using a drying wrack to hang the birds on while they await processing… you’ll see).
But without further ado (or more esoteric terminology), here are some photo highlights from the trip! I’ll do my best to explain molt limits through examples in the photos… but bare with me, it can get complicated. 😀
A great example of a molt limit in the wing of a female American Goldfinch. Most species undergo one molt each year (the pre-basic molt), but some undergo two (pre-basic, then pre-alternate). The best way to explain these molt strategies and patterns is to go through the life of this bird, as an example. It was hatched last summer (likely late in the summer, as Goldfinches are want to do) and had natal down for its first few days in the nest. Soon, it began growing its juvenal feathers during the pre-juvenal molt, and then became fully feathered, and all those feathers were of one generation (ie. all grown at the same time). A few months later and more into the fall, the bird started its pre-formative molt (also called the first pre-basic molt) into what will be its formative plumage. The bird replaced some feathers in the wing, and going into the winter, had two generations of feathers – juvenal and formative (also called first basic). This is where many species will stop in the molt cyle, but American Goldfinches (and a few other species) have one more molt to go through before the breeding season – the first pre-alternate (also called the pre-nuptual or pre-breeding molt). Over the winter and early spring, the bird replaced more body feathers, some wing and, possibly, even some flight feathers. Going into the spring, it now has three generations of feathers – juvenal, formative (or first basic), and first alternate. You get all that? Ok good.
A closer look at this fine lady’s replaced greater coverts. Note the darkness of the replaced feathers, and that they have less fraying/wear on the edges than the retained juvenal feathers, which tend to look rattier overall. Just above the replaced greater coverts, you can also see a few darker median coverts – these replaced during the first pre-alternate molt.
A Black-and-white Warbler: this bird had only one generation of feathers (called basic, or adult feathers) within the wing, making it an adult. In the spring, birds are aged as either Second Year (SY) or After Second Year (ASY). And for some birds that undergo complete pre-formative molts (and therefore you can’t tell if the feather replaced are formative ones or adult basic ones, and there is no molt limit visible), they are aged as After Hatch Year, meaning that you cannot say definitively whether they were born last breeding season, or many breeding seasons ago.
One of the coolest catches of the week (at least, to me because I have not seen many of these guys): an adult male Bay-breasted Warbler.
The delicate Yellow Warbler. Adult males of this species will have quite a lot of chestnut streaking on the chest and sides, while females will have less. Young females can almost completely lack streaking, and young males will have some, but not as extensively as adult males. Since the streaking is similar in young males and adult females, is important to age Yellow Warblers before making a decision on the bird’s sex.
Pointing out the molt limit in the wing of a Canada Warbler. In most warbler species, molt limits (that is, the point at which newly molted, adult feathers and retained juvenal feathers meet – essentially, where the bird molted up to) occur in the alula feathers (called A1, A2, and A3 – the first three, short feathers on the edge of the wing, just before/overlapping the first primary flight feather) between A1 and A2, less commonly between A2 and A3, or between A1 and the carpal covert (CC). Molt limits can be particularly hard to detect (especially in the green-plumaged birds ). When looking for molt limits, banders compare feathers within and (less commonly/reliably) between feather tracts. Some of the things we look for are the sheen/glossiness/light absorbency of the feathers within a tract (generally the primary and greater coverts), the amount of wear on the edge of the feathers, the coloration (whether more dull and brown, or vibrant, greenish yellow). the overall shape of the feathers (pointier on young birds, more broad and truncate on older birds), and the tightness of the feather barbules. So… lots to look at on each bird’s wing!
The underwing of a female Red-Winged Blackbird. Banders look for molt limits in the underwing coverts of this species (and others in the Icteridae family) rather than the greater or primary coverts on the upperside of the wing. Just when you think you know where to look, the Icterids throw you for a loop.
Here’s a shot of a young (SY) male Indigo Bunting’s wing. Like American Goldfinches, Indigo Buntings undergo an alternate molt prior to the breeding season. This bird’s wing has three generations of feathers – the juvenal feathers it grew just before leaving the nest (these are the most brown, worn-looking secondary flight feathers and primary coverts), the formative (or first basic) feathers it grew during its pre-formative molt in the fall (these are the darker brown, nicer primary flight feathers and the more brown (but still blue-edged) inner three greater coverts), and its first alternate feathers grown during its first alternate molt in the winter/early spring (these are the blue-edged, dark secondaries, greater coverts and the very blue body feathers.
To break up the bird pics (and give your mind a break if you are trying to understand molt limits…), here’s a beautiful sunrise at Powdermill. Banding means getting up before dawn, and sometimes that can feel like an insurmountable challenge… but then the sun rises and the birds start singing, and you forget being tired at all. 🙂
And now, onto Presque Isle State Park’s migratory banding station on Lake Erie…
An ASY male Chestnut-sided Warbler. So handsome. I could not even make eye contact.
An ASY male Magnolia Warbler. He, too, was looking pretty snazzy for breeding season.
ASY American Redstart. Only adult males with have such awesome black and orange coloration. Young males and females can look similar to one another, with more drab, gray plumage and yellowish coloration, rather than orange. BUT young males can have more orange and less yellow, and that’s how they can be differentiated from the females.
ASY male Redstart = Halloween
Examining the wing of a Blue-gray Gnatcatcher. If this bird were to have a molt limit, it would be pretty obvious, but its wing is even and all the feathers appear to be of the same generation. So what does that make it?? An ASY.
So nevermind the blurry gnatcatcher… just look at the drying rack in the background there, with birds waiting patiently in their bags to be banded and processed. GENIUS. I’d been trying to think of a way to safely hold the birds after extracting them and before banding them (other than around my neck) at the MAPS station. Problem solved.
And here is one of the most delicate, intricately-feathered birds of all – a Ruby-throated Hummingbird. The absence of red feathers on the throat = female.
LOOK AT THOSE TINY FEATHERS. Hummingbirds have about 940 of them – that’s more feathers per square inch than any other bird species. Say whaaat? And those feathers are pretty remarkable themselves – they appear iridescent and can vary in color depending on how the light hits them (a result of microstructures within the feather which deflect light differently).
A SY male Baltimore Oriole. They also undergo pre-alternate molts, as evidenced by this young bird’s wing. Notice the single retained juvenal greater covert, and the brown coloration of the primary coverts and A2 and A3 (A1 is replaced – the dark, higher quality feather near the top of the wing).
And here is an SY female Baltimore Oriole. She has replaced a few median coverts, and also one tertial feather on each wing (check out the dark feather on the lefthand edge of the outstretched wing – that’s one of the three terts). Terts are the innermost, last three secondary flight feathers, and these are replaced in Orioles during the first pre-alternate molt. Her tail is also a good example of an SY tail – it’s narrow and somewhat pointed at the tip, rather than broad and truncate as it would be in an ASY bird.
Though less colorful than males, female Baltimore Orioles are beautiful nonetheless.
And last, but not least, the coolest bird I ever held – a Cerulean Warbler!!!!! I had not even ever seen one until this day. I was so excited there might have been tears of joy. 😀
Presque Isle Bay, looking awesome because it is, and also because I had just held a Cerulean Warbler. ‘Twas a good day.
Check back soon for highlights and photos from the first day of MAPS banding!