Highlights from the 2007 Wilson Ornithological Society meeting

I recently attended the annual meeting of the Wilson Ornithological Society, held in the Boston area this year. In today’s column, I’ll describe some of the new research presented at the meeting.

The meeting began with a talk on Alexander Wilson, the father of American ornithology. The Wilson Ornithological Society is named in his honor. Wilson was born in Scotland in 1766. In his early adulthood, he was a weaver and peddler, a poet and a labor union organizer. He immigrated to Philadelphia in 1794, fearing he would be jailed in Scotland.

In In Delaware, he taught school and began drawing to alleviate his frequent depressions. He had the good fortune to meet William Bartram, the most famous and influential naturalist in North America.

In 1803, Wilson decided to describe and paint all of the birds of North America. Over seven years, he traveled over 10,000 miles studying birds. The first volume of the “American Ornithology” was published in 1808 with a second volume in 1810. Six volumes were published in 1813, the year that Wilson died. One last volume was published posthumously in 1814. All told, 264 species were covered in the nine volumes. Wilson’s volumes preceded John James Audubon’s by a decade, establishing Wilson as the father of American ornithology.

Wilson and Audubon had an amicable meeting in Louisville where Audubon was living at the time. Wilson asked Audubon to buy a subscription to “American Ornithology” and must have been embarrassed when Audubon showed him some of his own paintings of birds!

One of the highlights of this year’s meeting was a chance to see some of Wilson’s original paintings and the specimens on which they were based (including a Bald Eagle) at the Museum of Comparative Zoology at Harvard. Wilson’s paintings are accurate representations of the birds he saw but are not the artistic masterpieces that Audubon produced. It is not unfair to state that Wilson was an illustrator and Audubon was an artist.

Bob Curry and his students at Villanova University gave a talk on the hybrid zone between Black-capped Chickadees and Carolina Chickadees in southeastern Pennsylvania. They used DNA markers to determine if hybridization was occurred. Three sites were sampled: one southern site at Great Marsh where only Carolina Chickadees occur, an intermediate site in Nolde Forest where most individuals are hybrids and a northern site at Hawk Mountain with mostly Black-capped Chickadees but with some evidence of hybridization occurring.

Comparison to earlier studies indicates that the hybrid zone has shifted north about 15 miles over the past 15 years. The hybrid zone, now about 30 miles wide, seems to have broadened in recent years as well.

David Lahti from the University of Massachusetts gave a talk on the advantages of blue-green bird eggs. Most bird eggs are cryptically colored. Why would birds like American Robins lay blue-green eggs that should be easier to find for a predator than speckled or dark eggs?

Lahti suggests that the blue-green pigment in the eggs serves as a parasol for the developing eggs. In other words, the pigment may protect the developing embryo from the solar radiation in forest environments. He was able to show in the laboratory that the pigment keeps light rays from entering the egg, preventing the eggs from heating up.

Jim Chace from Salve Regina University in Rhode Island described research he and his students have been doing in Vermont on breeding Canada Warblers. Various sources of information, including the Breeding Bird Survey, indicate this species has been declining for the past 30 years. Yet, little is known of the characteristics of the habitat that males use when establishing territories. By comparing the vegetation within Canada Warbler territories with randomly chosen habitats, Chace and his students showed that males preferred habitat with denser shrubs and saplings and a greater ground cover of moss than randomly chosen sites within the large study area. This knowledge provides environmental managers with ways to improve habitat for Canada Warbler nesting.

Steven Reinert of the Block Island Banding Station in Rhode Island presented a talk on the bias of mist-net captures in monitoring landbird fall migration. Over the past 37 years, the Audubon Society of Rhode Island has hosted an annual Block Island Birding Weekend. Expert birders lead small groups of birders around this island, identifying and counting all birds during the middle of the fall migration season. Reinert used thee counts to compare to the relative abundances of landbirds he and his associates capture in their mist-nets over the same weekend. Over the 37-year period, 152 species were identified by sight and only 91 captured in nets. Most landbirds are absent or under-represented in mist-net captures.

[Originally published on April 7, 2007]