Banding Birds in the Bronx

Eric Slayton with Baltimore Orioles, ready for release

One morning in early May, I joined Eric Slayton, ornithologist, Wildlife Conservation Society researcher and artist/designer, as he banded birds on undeveloped woodlands owned by the Bronx Zoo. It was the final session of the Ornithology class Eric teaches at Columbia University’s Center for Ecological Research and Conservation (CERC).

Eric is completing a multi-year study assessing the quality of NYC parks as habitat for migrating birds. New York is an important stopover for many species as they make the long annual trek to and from their northern breeding territories.  The birds arrive in a state of near-starvation, having flown hundreds, even thousands of miles, burning up their fat reserves. What do they actually find when they land in our urban parks? Do they find enough healthy food in Central Park, Prospect Park, Inwood Park, or other urban parks to replenish their fat supplies so that they can reach their breeding grounds with enough energy to successfully nest, mate and raise babies?

We arrived at the study site on a gray, rain-threatened morning just after 7 AM.  For many of us, this would be our first opportunity to observe bird banding.  Warning us that he would be moving quickly, Eric clambered easily down a hillside to unfurl a mist net that reached from the muddy ground to height of about seven feet. Attached to vertical poles, a mist net is made of fine mesh fabric, designed to trap birds without harming them.

Eric checks the mist net

The nets are almost invisible when unfurled and are as soft as, well, Irish mist. Birds fly unknowingly straight into the net and quickly entangle themselves in the delicate threads, where they must wait for a researcher to release them.

While Eric was setting up a second net on higher ground,

Eric and a student unfurl mist net

our first captives were already awaiting release in the first net.

Catbird caught in mist net

Workstation in the woods

Eric quickly set up his work station, a rectangular folding table hidden in the bushes. Unpacking his toolbox, he arrayed the tools of the trade: a log book filled with cryptic abbreviations and columns, tiny marked leg bands in different circumferences, pliers, a scale and graduated PVC tubes.

Tubes, Pliers, scale, bands

Log book

As soon as he finished setting up, Eric freed the first unhappy captives, delicately untangling the tiny feet and beaks.

No longer netted; not yet free

Eric would spend the morning moving swiftly between the two nets and the table, with us students following after him like ungainly goslings, willing but mostly clueless. Now we trooped back up the slope to the workstation, where Eric selected the right size band,

Chains of bands

slipped it onto the bird’s leg

and used pliers to close the circle.

Waterthrush gets banded

Next he adeptly slipped the bird headfirst into a plastic tube so that it could not struggle or flap its wings, and placed the bird-in-tube head-down on the scale for weighing.

Ignominious catbird weigh-in

After recording the weight in the logbook, he released the bird from the tube. He blew on the feathers beneath the tail to examine the bird’s cloaca, then blew on its breast to part the feathers around the clavicle. He ascertained the bird’s subcutaneous fat deposits, simply by looking and rating the bird’s interclavicular area on a scale of zero to four, as follows: 0. no visible fat, 1. some visible fat, 2. nearly filled with fat, or 3. completely filled with bulging fat pad.  Blowing on the feathers may also reveal a female bird’s brood patch, which is an area where the feathers have dropped off in order to allow the bird to directly transmit her body heat to eggs and nestlings.

Blowing feathers apart

Pointing out oriole's feathers with a pencil

Red-winged blackbird wing

For many birds, plumage revealed whether it was in its first year (HY or Hatch Year), or older (AHY or After Hatch Year).

Spreading the beautiful wings, Eric showed us how to count wing feathers.

He showed us the exposed vein under the wings where researchers draw blood (although he was not doing blood work today).

Surface vein on catbird

He showed us how to hold the birds safely and how to release them. We could feel the birds’ little hearts beating fast in our gently cupped hands and then the scratch of their almost weightless feet on our open palms, in the moments before they spread their wings and flew off to freedom – or, in the case of one unfortunate catbird, directly back into the mist net.

Everything is recorded,

Recording data

but first, everything is admired.

Beautiful Baltimore Boys

Within a couple of hours, we had observed the banding of four catbirds, one waterthrush, two Baltimore orioles and two red-winged blackbirds. In addition, five previously-banded birds were caught, assessed and released.

Furling the nets

As we headed home, the rain began in earnest.

Explore posts in the same categories: 2010, Birds, In the City, May

Tags: baltimore orioles, banding birds, CERC, Eric Slayton, NYC bird habitat, NYC bird migration stopover, studies on urban habitat

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