All spring I’ve been trying to get down to the National Forest to tag along with Scott Stoleson’s team. I never made it… until the first full day of summer! This is the second year they have been targeting Cerulean Warblers for banding. Why Ceruleans? Audubon’s Watchlist entry for this species explains:
Formerly one of the most abundant breeding warblers in Ohio and the Mississippi River Valleys, its population plummeted in the 1900’s due to habitat destruction.
Cerulean Warblers nest in the upper canopy of mature forests in North America. Their wintering grounds are in South America. Both breeding and wintering sites have been changed considerably by human activity through the 1900s causing one of the sharpest population declines of all warblers… 70-75% overall decrease, according to Scott.
The mist-netting demonstrations that Scott’s team does at Audubon in spring, and the MAPS projects run by Tom LeBlanc throughout the summer do not target a single species. In those projects, several nets are set up in various locations near the banding station and nearly the all birds that come into the nets are banded. It’s a little trickier to target just one species. Here’s how Scott’s team caught its first bird:
- We drove out to a spot in the National Forest where Ceruleans had been spotted before. We watched and listened. It didn’t take long to hear a male singing fairly close to the road. Scott played a recording of Cerulean song to draw the bird in. During breeding season, Ceruleans are fierce protectors of their territories. The sound of another male nearby was sure to cause concern. Sure enough, down he came to investigate.
- All binoculars went up to see if this male had a band or not. (Having the curse of extremely bad eyesight since childhood, I was astounded they could find the tiny bird so quickly, let alone see an even tinier band around the fellow’s ankle!) This one was unbanded! The team mobilized to catch him. Now remember – Cerulean Warblers like the upper canopy… so a standard ground-level net is not going to work.
- No, Linda is not trying to shoot the bird with a bow and arrow! Having located a suitable branch from which to hang the net, Linda shoots an arrow attached to fishing line. Mike mans the reel.
- Up and over a high branch goes the arrow. When it returns, the fishing line is removed from the arrow and attached to a (tan) rope. Mike reels in the line until the rope is up and over the branch.
- Next they will attach a pulley system (that’s the blue ropes in the picture) to the (tan) rope and hoist it all the way up to the limb. Mike crawls into the brush to find a tree that will serve as an anchor for the system.
- In the meantime, Scott and Emily are busy setting up the frame that will hold the mist net. The MP3 player and the decoy are attached in the upper center part of the net.
The frame is assembled.
Attaching the mist net.
- The net is hoisted up and secured. A (black) rope on either side of the frame will allow Emily and Linda to turn the net to the desired angle and stabilize it so it doesn’t spin randomly.
Scott turns on the MP3 player.
Up she goes!
The net is now in position, the decoy singing away.
- Then we wait and watch. We are lucky. June 22nd is pretty late in the season to find males that are still aggressive about defending territory. Many pairs are already feeding young – some that have fledged. This little guy displayed all the classic behaviors of an aggressive, defensive male, and while it took a bit of time, he did finally “attack” the source of the other song.
- The net is lowered; Scott removes the bird. Linda, Mike, and Emily disassemble the net contraption and Scott processes the bird.
- The bird will actually get 3 bands: the standard numbered aluminum band will go on the bird’s left leg, and two colored plastic bands will go on the right. (Last year’s birds were banded with aluminum on the right, colored on the left.) These combinations will help the team identify individuals in the future without having to re-capture them. (This year, the team has spotted 5 birds that they banded last year – most having returned to the exact same nest site.)
Purple and blue colored bands for the right leg, aluminum for the left.
Attaching the aluminum band.
- After weighing and many photos, the pretty fellow is released (by me!).
Weight: 9.3 grams
A fine Cerulean Warbler Male – with new jewelry.
Scott takes many photos – from all angles.
And they graciously let me hold him for a photo opp, then release him.
This first bird we caught and processed made it all look so easy. We tried two more times – not on the road, but halfway to the summit of steep hillsides. In the second attempt, the net placement was apparently on the boundary between two territories. The bird on one side would not go in; the bird on the other side would not go in. The third placement seemed perfect, but the birds were not interested in the “intruder’s” song… they seemed only interested in eating. In fact, I watched through binoculars as one warbler extracted whatever critter rolls up the leaves… that was fascinating!
It was a fun, exhausting day of learning for me. If I could do my life over, I would pursue a career in which I could do this sort of thing. Maybe next time around? For now, I’ll live vicariously through the lives of those who let me tag along.
Learn more about Cerulean Warblers:
- Audubon Watchlist – Cerulean Warbler
- Bird Life – profile of Cerulean Warbler
- Cerulean Warbler – All About Birds, Cornell Lab of Ornithology
- Cerulean Warbler Atlas Project – Cornell Lab of Ornithology
- Living on Earth – interview with Greg Butcher, Director of Bird Conservation, National Audubon Society
- An Enigmatic Warbler – by Marcia Bonta