Read more about CVWO's Songbird Research here.

Why are we studying Prothonotary Warblers? These yellow gems of the swamp are most vulnerable to destruction of their habitat, both in North America and in Central and South America. Partners in Flight has placed the Prothonotary Warbler on its US/Canada Watch List. Local, volunteer-based nest-box programs for the species are becoming more common in regional and county parks to repopulate areas where populations have dwindled or disappeared.

Officially she is 2430-19974, but we're calling her Chelsea, because she lives in Chesapeake, VA, on the Northwest River in the spring and summer. Chelsea is a female Prothonotary Warbler (Protonotaria citrea) and she is 5 years old. How do we know this? Chelsea is one of hundreds of Prothonotary Warblers banded since 2009 at the Northwest River in Chesapeake as part of a network of nest boxes set up to study Prothonotary Warblers around eastern Virginia.

The Prothonotary Warbler breeds in wet bottomland hardwood forests, primarily in the southeastern United States. This warbler is a small songbird, but it is large for a warbler. Its head and chest are bright yellow, almost orange, and the back and wings are gray with no wing bars. Since 2008 Northwest River Park has hosted 100 nest boxes for Prothonotary Warblers. Coastal Virginia Wildlife Observatory is grateful for the park's support and assistance on this conservation project. Chelsea was first banded by licensed volunteers June 14, 2009 at nest box 5 on the Northwest River. When she was banded she was determined to be one year old. In 2012, we recaptured Chelsea at box 6 incubating 5 eggs while her 2009 nest box hosted a new female.

Chelsea was most recently recaptured May 10, 2013 at box 4 incubating 5 eggs, very close to her previous boxes 5 and 6. On May 21, Chelsea had 5 nestlings too young to band only 3 days old! On May 28, her five nestlings were banded. On July 9, 2013, we banded four nestlings in box 4. Very possibly they were Chelsea's second clutch! Unfortunately we were not able to capture the female in box 4 in June but it is very likely that the female was Chelsea!

Each year volunteers and biologists capture less than two dozen Prothonotary Warblers that were banded as an adult or as a nestling in previous years. That's not very many recaps out of the hundreds of birds banded since 2009. We are not able to capture every nesting female some are just too fast out of the nest box for capture. Also, not every female returns. Many do not survive the migratory trips or the winter. So when we recap a bird banded in 2009, we gain a bit more insight into the life history of this species and continue to marvel at the strength and endurance of this startlingly yellow, 15-gram warbler. Fifteen grams is less than the weight of three quarters!

We do know a few things about Chelsea's long life. Five years is a long life for a warbler. She has made at least 5 round trips to her wintering grounds, migrating from Chesapeake to Central America or northeastern South America. As the warbler flies, that's almost 4,000-5000 miles for each round trip! Her winter habitat is primarily mangrove swamps. Chelsea likely hatched near Northwest River Park in a natural tree cavity in 2008, probably in an abandoned Downy Woodpecker cavity. When nest boxes were installed on poles in the water along the shoreline of the Northwest River, she built her 2009 nest in box 5 and probably raised five fledglings with the help of her mate. Most likely, she had a second clutch or set of eggs that year.

In 2013, she arrived in mid-April, a few days after her mate, who established his territory by placing thin layers of moss inside one or more nest boxes. It is unlikely that Prothonotary Warblers have the same mate from year to year, but mate fidelity within a season is fairly common. Chelsea then set to work to build a complete nest quite possibly with no help from her mate. About 2/3 of her nest is moss. The upper 1/3 features a tidy cup of tender cypress twigs and rootlets. She then lays one egg a day until her clutch is complete usually 5 eggs in her first clutch of the season. She incubates her eggs for about 14 days.

The nestlings grow incredibly fast. They fledge leave the nest when they are only 10-11 days old. For the nestlings to grow so fast, both male and female Prothonotary Warblers must feed the nestlings high protein food constantly. Food includes butterflies, moths, flies, beetles, spiders, caterpillars, and assorted larvae. About a month and a half after fledging, young Prothonotary Warblers closely resemble adults. At that time they will also begin some pre-migratory dispersal. By late August the majority of young and adult Prothonotary Warblers will have left the area to begin migration to their winter grounds.

Source: Petit, Lisa J. 1999. Prothonotary Warbler (Protonotaria citrea), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the 
Birds of North America Online.

Read more about CVWO's Songbird Research here.

The Story of "Chelsea" at Northwest River Park


Coastal Virginia Wildlife Observatory