Cape May, Naturally is a column written by a rotating cast of experts at the NJ Audubon.
Within the past two months, I’ve had two separate friends tell me they saw an Eastern Bluebird for the first time, and their reactions were identical: “It was the most beautiful blue I’ve ever seen!” Although they don’t know each other, we all live in the same area on the southern edge of the Pine Barrens in Dennis Township and I was intrigued that they both had “firsts” at around the same time.
Eastern Bluebirds, along with their counterparts Western and Mountain Bluebirds, provide an interesting example of how human activity impacts a species over time. Preferring grasslands with low shrubs, they were common in their territories when European settlers arrived and in the late 1700’s they even benefited from the clear-cutting of forests for lumber. However, the tide quickly turned with the introduction of European Starlings and House Sparrows, two more aggressive cavity-nesting species that outcompeted them for precious nest holes.
The expansion of farming, especially the use of pesticides that killed off the insects that represent the bulk of a Bluebird’s diet, also contributed to population decline and by the 1950’s they were considered rare.
Public interest in Bluebirds soared in 1977 after National Geographic Magazine published an article, “Song of Hope for the Bluebird,” by Dr. Lawrence Zeleny. The article introduced the notion that specially designed man-made nest boxes, when carefully placed, could improve the breeding success of the species. The North American Bluebird Society (NABS) was founded the next year by Dr. Zeleny and others to spread the word.
Like Purple Martins and Tree Swallows, Bluebirds have benefited tremendously from human intervention in the form of man-made nest boxes. The global population of Eastern Bluebirds alone is now estimated at 23 million. In their case, there’s even a word for it, “Bluebirding,” ie., setting up and tending man-made nest boxes in bluebird-friendly habitats and/or creating Bluebird Trails with a series of nest boxes.
And here’s a fun fact. Bluebirds aren’t actually blue. Neither are Blue Jays or Indigo Buntings! They just look blue to us. A note on the Smithsonian website quoted Scott Sillett, a wildlife biologist at the Smithsonian Migratory Bird Center, who explained:
“Red and yellow feathers get their color from actual pigments, called carotenoids, that are in the foods birds eat. Blue is different―no bird species can make blue from pigments. The color blue that we see on a bird is created by the way light waves interact with the feathers and their arrangement of protein molecules, called keratin. In other words, blue is a structural color. Different keratin structures reflect light in subtly different ways to produce different shades of what our eyes perceive as the color blue. A blue feather under ultraviolet light might look uniformly gray to human eyes.”
Well, thank goodness for lightwaves, protein molecules and keratin, because Bluebirds are gorgeous in my eyes. And thanks to all the folks “bluebirding” in southern New Jersey, because Eastern Bluebirds are now a reliable sight in my yard and on many of the birding field trips at the Cape May Bird Observatory. Check out our schedule of activities at birdcapemay.org and learn more about helping Bluebirds at nabluebirdsociety.org.
