Let me begin by saying that I’m an equal-opportunity nest box enthusiast, so it’s great that there are Carolina chickadees, tree swallows, and house wrens using the boxes at WVWA’s preserves. That said, I’m particularly interested in bluebirds. Why?
But also because while out at Crossways a few times over the winter, hearing and seeing bluebirds, I realized we really have no idea whether or not the individuals that winter on our preserves are the same as those that nest or were born there. Or if they are stranger bluebirds that replace our breeders if and when they move a little south.
From what information exists, bluebird movements depend on what part of their range you’re looking at; northern populations are medium-distance migrants who move south for the winter, while those in our part of Pennsylvania seem to stay year-round. But there appears to be variability – spend a few minutes looking at range maps, and you’ll notice this.
As I stared through my frosty December binoculars, I thought, “hey, it’d be cool to know who you people are.” So, in addition to our Nest Box Project, we’re also color banding nestling and adult eastern bluebirds.
Color bands are exactly what they sound like, and they make it possible for us to identify individual birds at a distance, known as “resighting.” By resighting, we can determine exactly what bird we’re seeing without have to re-catch it to read its band number. A combination of banding and resighting data allows us to gain a greater understanding of a bird’s life – things like how they interact with others of their species, where they spend their time, and their movements within a landscape.
Color banding allows us to identify which birds are on site and when, their site occupancy across seasons, their social behavior during the winter and the breeding season, whether there are local or migratory movements in a population and, of course, whether a breeding pair stays together and returns to the same breeding place each year.
By color banding nestlings, we have the opportunity to determine if they stick around over the winter, and whether or not they return next year to the same site where they were born (their “natal philopatry”). We can also look into whether or not they help their parents feed next year’s nestling (cooperative breeding, which has been documented in bluebirds and is an extremely interesting evolutionary life choice).
These are all important aspects of bluebird life history; knowing the answers and better understanding bluebirds means we will also better understand their needs across a season, and therefore manage our lands more effectively, both for them and similar species. What if our bluebirds don’t stick around? That could mean that their survival depends on having quality habitat not only where they breed, but also elsewhere. And if they stay, we will know their survival is dependent on our preserves and what food and cover we provide for them over the winter.
And all of that brings me to telling you about the fantastic day I had a couple of weeks ago, when this happened:
Can you even? I can’t.
Catching specific adult birds usually involves target mist netting. Different from passive mist netting (like during MAPS banding, where you catch whatever passes through), target netting involves strategy, stealth, and cunning. Or so I tell myself and others.
In this case, I watched the adults visiting the nest beforehand to get a sense of their angle of approach, then set up a net a day in advance to acclimate the birds to its presence and trick them into a false sense of security (which I did only after reading several papers about the safest capture method for nesting adults).
Despite their seemingly calm, peaceful demeanor, Bluebirds are surprisingly confrontational. And, I might add, 100% fearless. Because the second I approached the net/nest box area, both parents came out of nowhere to hover threateningly over my head like little, blue helicopters fueled by aggression and rage.
So I opened the net and slipped away to my mini banding station…
After just a few high-octane minutes of reading the Pyle Guide and waiting, I looked up to see the male attempt a flight toward the box and get caught in the net’s top pocket.
*a moment of silence for this absolute success*
I sprinted over with my adrenaline legs to quickly extract him, which of course made the female extra-determined to attack my face – and she blindly hit the net, too.
With color banding comes the fantastic opportunity to name each bird based on colors or personality. And so, the male is hereafter known as Gisby.
And his wife, Whibl:
To read and record color bands, we look from the bird’s left leg to its right leg, and from top to bottom. For example, the bands on Gisby (jizz-bee – for pronunciation clarity) are read “green over silver, blue over yellow,’ and on Whibl (why-bull) as “green over silver, white over black.” In short form, these can be recorded at GS/BY and GS/WBK… Can you guess how I thought of their names?
The day after this seamlessly-executed adult capture, I banded all five nestlings, who were about 10 days old.
At this point, the vocalizations made by Gisby and Whibl as they took turns dive-bombing me were undoubtedly just a string of profanities. But anyway, the nestlings were also given color combos and identifies.
Even though they’re still just tiny little birds and recorded as ‘unknown’ on the banding data sheet, you can make a guess about each nestling’s sex based on the vibrancy of the blue on their emerging feathers. This I learned from a fellow bluebird bander and go-to nest box advisor (thanks, Gigi!!). Clover, for example, has some pretty bright blue feathers coming out, so is likely a male, while Sunshine has more brown-looking feathers and is likely female.
Hopefully, the nestlings will stick around and we’ll be able to say with more certainty once their feathers fully emerge!
Speaking of which, any time you visit Crossways Preserve, keep an eye out for these birds and report sightings by email. The more we learn about who’s where when, the more information we have to help us answer some of the questions I mentioned earlier.
If you do see them, include as many details on what you saw in your message as possible – time and date, location on the preserve, habitat type the bird was seen in, its behavior/what you might have seen it eating, etc. The same goes for seeing a color banded bluebird anywhere in the area, not just at Crossways.
Here are the color codes for recording their band combinations:
G = Green B = Blue R = Red BK = Black W = White Y = Yellow
Pretty straightforward. ;D
Alright, stay tuned for highlights from our first banding day, coming soon!