Fall 2020 banding comes to an end

Today was the last day of our banding season; it's always bittersweet. Most of our songbirds are gone, the leaves have changed and fallen, and the weather has turned brisk. This season's ending was different. A newer, albeit, strange new normal has emerged in our lives that we are adapting to. As the nets and equipment get tucked away, I have hope that our community can come together again in 2021. Sure, it'll be different but the joy and passion we all share will be just as strong as ever.

Stay tuned for a full summary of the season in the coming days. Who was our most frequent capture? What was the oldest bird we caught? Do you remember any rarities we caught? 

Banding Jargon Part 4: Mist Nets

 

One of our primary tools at the station is the 'mist net'. It's a specially designed trap that safely captures songbirds. It's efficacy relies on being nearly invisible to the human eye as all captures are passive, meaning that we don't use any lures or bait to attract birds into the mist nets. Today, we figured we'd share some special mist-net terminology that you may have heard us use (see if you can match the terms to the parts on the photo below!).

Guy lines: These are the ropes that anchor the poles to the ground and provide counter tension to keep the net upright and in place.

Loop: These are the thick rope circles that are attached at each end of the five trammels. The loops are used to mount the mist net onto poles.

Mesh: This is the fine micro-filament (often colored black) netting that makes up the mist net. The size of the mesh (think, a grid of squares) varies depending on what species is intended to be captured. We use a 30mm by 30mm which is typical for most songbird capture.

Pole: Each mist net is typically erected using two poles. The loops on each end of the mist net are slipped on the pole, the poles are staked in the ground and held into position with at least two guy lines. 

Shelf (or Pocket): These are the five areas of the mist net that are created by the five trammels. Some banders might refer to these loose, draping mesh as 'bags' because when there's a bird captured in it, it's like it's in a bag!

Trammel: These are the five horizontal lines that extend from pole to pole that give the solid mesh panel shape and thus create the shelves/pockets. These trammels attach to the poles using thick rope loops that allow the height of the net or spacing between the shelves/pockets to be adjusted.

(from the North American Banders Council passerine manual)

Clear skies and a Black-capped Chickadee

We caught half as many birds as yesterday, one recaptured Black-capped Chickadee. Despite the low numbers, we had a productive day preparing for the end of the season and enjoyed beautiful clear skies and nearly warm temperatures by the end of the day.

Our 32nd species of the season, a Canada Jay!

 

Though things have slowed down we were excited to capture another first-of-season, a Canada Jay! We rarely capture these tough Interior residents, but enjoy their bright and fun personalities.

Bre'r Fox Visits CFMS

There’s a great deal of valuable scientific data that can be derived from a bird banding study. However, ethics demands that banding should only be conducted in a way that doesn’t harm the birds being captured.

 
Predators pose a special problem to a banding program. Songbirds trapped in mist nets are completely defenseless and their fluttering can attract the attention of passing predators. Merlins and sharp-shinned hawks are small migratory raptors that travel through Fairbanks along with the songbirds. When we see either of these birds, all nets are closed in the vicinity until they pass through. Most people think of squirrels are vegetarians, but they will also occasionally attack a songbird in a mist net. Squirrels exhibiting predatory behavior are quickly trapped and relocated away from Creamer’s Field.
 
We’re experiencing a special problem this year with a young fox that has developed an interest in the mist nets. Foxes don’t migrate so we can’t just close nets for a few days and wait for it to move on. They’re also too big to trap and move. As a response, we’ve had to close all of the nets on the land for the rest of the season. Our capture numbers will be reduced as a result, but we’d rather lose data than harm birds!

~Laurel

Could you migrate like a songbird?

What can you do purely from instinct? Catch yourself when you’re about to trip? Chew your food? I’m sure you can think of a few things. Maybe you have a very strong ‘intuition’. But do you think it would be strong enough to get you through the following scenario?

I drop you off in the middle of the vast boreal forest. I take your smart phone and wallet and give you just enough rations to survive. You were blindfolded on the way in, so you have no idea where you are, and you’re completely on your own. Using nothing but your ‘intuition’, do you think you could get all the way to northeastern South America? Under your own power—no hitchhiking! There are only a few precious weeks of moderate weather before brutal cold sets in. How do you think you’d fare?

People often ask us if adult birds have to show babies the way to the wintering grounds. We are constantly catching flocks of birds at CFMS made up entirely of very young birds (born this year). There are no ‘leaders’ in this group, no elders who have made the journey before. Just a bunch of 2-month-old warblers and sparrows.

So... how do they do it?! These birds are equipped with a slew of instincts and sensitivities that allow them to find their way to the wintering grounds completely on their own. I imagine it would feel like following an intuition. They have the ability to ‘see’ Earth’s magnetic field because of magnetite in their brains—so they can tell north from south. They also register changes in the photoperiod (the amount of light in a day) in order to know how to time their migration. Songbirds can see polarized light, and some birds use the sun and stars to navigate. They may eventually learn landmarks—but they probably don’t know them on their very first migration. They also have to know to fuel up before their journey, and somehow most of them know to make their big flights at night. There may be a social element to this, as most of these birds are traveling in groups, but it isn’t the case that some birds must already know the way. The process is largely innate, instinctual. No one even teaches the birds how make sense of the instincts. They just know!

Of course this isn’t true for ALL birds—Whooping Cranes are famous for following a fake Whooping Crane in order to learn their migration route. Basically, it seems every species has their own little tricks for getting from one place to another—the task of crossing the globe twice a year is enormous and complicated. There is no quick answer! And it’s definitely not fully understood yet.

Many birds are so good at the process that they can fly all the way from Alaska to South America and back to Alaska—and wind up in exactly the same breeding territory they used the previous year. That is a lot of information to process and remember... And they don’t even get to take notes!

If you’re interested in learning more about the magic of avian migration, I recommend the book Living on the Wind: Across the Hemisphere with Migratory Birds by Scott Weidensaul. And if you’re interested in the process of emergence (social intelligence without coordinated leaders), there’s a classic Radiolab episode about that.

PS—I promise I won’t leave you stranded in the boreal forest. ...without your smartphone. ;)

~Laura

P.S.S. We closed early today due to high wind and rain.

American Tree Sparrow Invasion!

We had a surprising morning when we arrived at Creamer's Field. American Tree Sparrows were everywhere! We silently opened our nets and had a productive morning of captures. What a nice fall treat!

How many toes on that first-of-season??

We had another great bird visit the here banding station this morning. This adult female American three-toed woodpecker is the second woodpecker we have banded this fall. 

These woodpeckers often take advantage of disturbed areas where dead, or burned trees can house bark beetles and other insects. Their foraging strategy is unique in that they will chip bark off of the trunks of trees, looking for insect larvae. American three-toed woodpeckers also breed the furthest north of any other woodpecker in North America, with nesting pairs reported as far north as the Brook's Range. 

Hopefully we can catch some of the other local woodpecker species this fall that also inhabit the woods around Creamer's Field!

-Dave

Ask-a-bander: how often do you recapture birds?

Almost all the birds we recapture at CFMS were originally banded here at the station. About 1% of birds from the current season are recaptured the next year (or later!) at CFMS; those species typically include Black-capped Chickadees, Downy and Hairy Woodpeckers, Hammond’s Flycatchers, Dark-eyed Juncos, and Yellow-rumped Warblers. We’re the farthest north station in North American and it’s very rare that we capture a bird that was originally banded elsewhere; the last time that happened it was a Sharp-shinned Hawk that was originally banded in Nebraska!

Another first-of-season, a Hermit Thrush!!

Today we banded our first hermit thrush of the fall. This is not unusual timing as these thrushes migrate north for the breeding grounds later than other thrushes and also head south later than other thrushes. The song of the hermit thrush has been described by many as "the finest sound in nature". If you hear a flute like melody coming from the forest it may just be the hermit thrush. Often times their song may sound as if the bird is farther away than it actually is, so keep and eye out too! 

~Chelsea

Who says bright yellow isn't camouflage?

Most of our warblers has passed through on their way south. We were surprised and joyful to see this charming adult female Wilson's Warbler! She'd certainly be easy to miss among all the yellow leaves filling our trees!

First-of-Season: Red-breasted Nuthatch!

We had a very neat visitor here at the banding station this morning. This juvenile red-breasted nuthatch is the first nuthatch we have caught this year, and the first we have caught in the past couple years. These small songbirds can be found in mature coniferous woods where they often nest in cavities inside spruce trees. Nuthatches are well known for their unique foraging strategy of climbing up and down tree trunks looking for small insects. If you can't find one by sight, listen for their unmistakable car alarm-like song. Although many nuthatches in the lower-48 migrate to warmer climes during the winter months, most nuthatches here in Alaska are year-round residents. These birds love to frequent bird feeders, especially in colder months. Put a suet feeder in your yard and maybe you can attract your own nuthatches!

-Dave

Attachments area

Junco 2811- 092295 Comes back!

A "baby" Junco

Today at Alaska Songbird Institute's banding station, we caught a slate-colored junco that had already been banded. That’s not such a rare event. Birds often spend a few days at Creamer’s Field resting and eating in preparation for migration. When we initially catch it, the bird gets an aluminum band with a 4 number prefix and unique 7 number sequence attached to its leg. During its time at Creamer’s, the bird might get caught in the mist nets again while it forages and travels through the refuge. This junco’s band number was 2811- 092295. Its band looked old and the band number wasn’t in our 2020 data. With mounting excitement, we realized that this bird had been banded elsewhere, or at the ASI station in previous years. A data search revealed that junco 2811- 092295 was banded at Creamer’s Field in August of 2019. At that time, the bird was recently hatched and we couldn’t determine gender by its plumage. Today, we could tell that this bird was an adult female. What else can we tell from her band? We know that this tiny bird survived the round-trip migration to her wintering grounds somewhere in the Midwest, and back again. We can guess that this summer she found a mate and successfully raised her first brood of nestlings on or near Creamer’s Refuge. We hope we’ll catch her again next year and be able to read another chapter of her life story!

~Laurel

Another Rain Day

 We had yet another wet and rainy day here in Fairbanks, thus we did not get to band birds today. We have noticed quite a decrease in bird activity around the banding station in recent days. The last of the Sandhill Cranes are leaving the fields, no more flycatchers can be heard in the canopy, geese are flying in formation and heading south, and the ground is covered in freshly fallen birch and poplar leaves - all signs that winter is coming! Fingers crossed we have better weather next week!

-Dave

Bird Banding Jargon Part 3: Ageing and Sexing Characteristics

American Tree Sparrow

It was a beautiful fall morning today, and our first so far this week that we were able to get started on time. Suffice it to say, we've been ready for the rain to stop! Despite the bird activity in the vegetation around the station, our capture rate has dropped. 

Without an exciting story from the day to tell you, I've decided to take another dive into bander jargon. Part 3 of the 'Bird Banding Jargon' series is themed after ageing and sexing characteristics or techniques. These are some of the "clues" we look for when trying to determine how old a bird is or whether it is male or female. 

Brood Patch (BP): This is a naked patch of skin that is developed on the abdomen of a bird when they are incubating eggs and brooding young. Almost all female songbirds develop a brood patch, while some males (species dependent) might develop a partial brood patch. The presence of this complete brood patch in the spring reliably indicates that the bird is a female. Sometimes late nesting or individuals that complete multiple breeding attempts in a year may have a residual brood patch in the fall that allows us to determine sex. 

Cloacal Protuberance (CP): During the breeding season a males cloaca distends from the body cavity to store viable sperm and assist with copulation. This distended cloaca is referred to as a cloacal protuberance. Similar to a brood patch, the presence of a cloacal protuberance during the breeding season allows a bander to determine the sex of an adult bird as male. Females do not develop cloacal protuberances. 

Molt: This is the process of losing and growing in new feathers. Banders use known schedules of when birds are expected to replace certain feathers, and look for these patterns to determine the birds age. These schedules vary for each species, and are being increasingly used to verify and determine age of a bird. Stay tuned for a more in-depth conversation on molt!

Skulling: This is a technique that is currently the most reliable at ageing passerines during the fall. This process involves the bander gently parting the feathers over the posterior areas of the head to look through the skin (songbird skin is nearly clear!) to determine the level of skull pneumaticization. When songbirds fledge their skull is only composed of a single layer of bone; over their first year of life they will develop a second layer of bone under the first, a process called skull pneumaticization. The resulting air pockets and columns of support between the two layers are highly visible, and easily allow a bander to determine if a bird is an AHY or HY. AHY's will have completed the process of skull pneumaticization, and HY's will actively be in the process of skull pneumaticization which is seen as "windows" or "gaps" in the completed skull. It's kind of like a soft spots of a baby.

There is still so much we don't know about birds; even our most common captures including the most common warbler species in the U.S., the Yellow-rumped Warbler, are mystery when it comes to understanding whether they are male or female in the fall. When we examine a bird in the hand, a bander is considering a suite of evidence (with emphasis on the methods or characteristics above) and determining if it is conclusive enough to report with certainty how a bird is and its sex. Ageing birds in the fall for the species we capture is fairly straightforward and it's uncommon for us to be uncertain, but the exact opposite is true for determining sex! When we're uncertain, regardless of how we feel about what the answer might be, we often report age and sex as 'unknown' as it's of utmost importance to collect robust data. Plus, imagine how embarrassing it'd be for someone to recapture a bird you called a male as a female?! 

Questions? Leave your questions in the comment sections and I'll respond with an answer!

~Claire

A "fall" of Wilson's Warblers!

Wilson's Warbler

Wilson's warblers are one of many migratory species we band here at the station. Birders have no trouble seeing these flashy little birds. These insectivores are often seen moving rapidly through bushes and trees to glean insects from the leaves. They are also commonly seen in the U.S.A. and Canada because they nest coast to coast in North America, but are more common in the West.

Fun Fact: A collective of warblers has many nouns, including a confusion, a wrench or a fall.

~ Chelsea

Our bread and butter(...butts!)

See the "butter"?

We all know Yellow-rumped Warblers at CFMS. They’re our most common capture, especially in the fall. Myrtles, MYWAs, Butterbutts—they’re the bread and butter(butt) of this station. We, as birders, tend to get a little bored of our most abundant birds... but while they are commonplace, they’re far from boring!

The Yellow-rumped Warblers (Setophaga coronata) here are the subspecies known as Myrtle Warbler (S. c. coronata), with white throats and white eyebrows. While in Alaska, they are mostly insectivorous (and are pretty acrobatic, sallying like flycatchers), but on their wintering grounds they eat berries and fruits, an unusual dietary choice for warblers. In fact, they got their name from their habit of eating the wax-myrtle berry (Myrica sp.). Imagine a gut biome that can handle all those food items! This is what allows them to winter further north than most other warblers. In the winter, Myrtles can be found in the southeastern U.S.—but also as far south as Central America and the Caribbean. Unfortunately, we don’t know exactly where our Creamer’s Field Myrtles go, but hopefully one of our many banded birds will be recaptured on their wintering grounds or migration stopovers soon.

This year, we’ve been catching tons of hatch-year Myrtles, meaning lots of Myrtle moms were busy building nests (they do it without the help of a male) and feeding chicks this summer. (The males DO help with that part.) Myrtles build cup nests, usually in a conifer, delicately lined with hair (sometimes from moose!) and feathers. As fall progresses, the chicks are losing their fuzzy baby feathers and the adults have lost their bright blue-and-black summer feathers, but their yellow patches are still highlighter-bright. Hope everyone can get out and catch a glimpse of a few more Myrtle butts this year—come February, we’ll surely be missing our buttery companions.

Banding got off to a late start today due to weather, but with only a few nets open, we still managed to catch a good number of birds—including our first of the year American Tree Sparrows.

~Laura