Bell's Vireo, and its enigmatic history in Ohio

A Bell's Vireo (Vireo bellii) sings its charismatic song of scratchy gurgled phrases from the cover of a small Chinkapin Oak (Quercus muehlenbergii). "Thicket Vireo" would be an appropriate name for this denizen of scrubby early successional zones. The story behind the "Bell's" part of the little bird's appellation is an interesting one. John Graham Bell was a taxidermist and - as probably most taxidermists of his day were - a collector of animal specimens. Bell was part of John James Audubon's expedition to the Dakotas and vicinity in 1843. The team had encamped near a trading post named Fort Union, when one of the fort's hunters shot a nearby American Bison. Audubon and Bell hustled to the site of the kill, pistols in hand, only to realize the huge bull was not dead when it stood and charged them. The quick-thinking Bell dropped the bull with a well-placed rifle shot, when it was nearly upon Audubon. In gratitude, Audubon bestowed the newly discovered vireo with the taxidermist's name (the Bell's Sparrow is also named for John Bell).

An eBird map showing Bell's Vireo records in the Midwestern Great Plains and prairie regions. While some of the Ohio records probably represent migrants, most are of breeders, or at least attempted breeders. Records drop off dramatically to the east of Central Ohio - the latter region represents the easternmost limits of this species core breeding range, although Bell's Vireo quickly becomes much more common westward. In Ohio, it is a rarity, although regular and of annual occurrence at a number of nesting haunts.

This is a well-known map constructed by Ohio State University ecologist Edgar Transeau in 1935. The black zones indicate Transeau's depiction of prairie distribution, although even by the time he made the map, much prairie had already fallen to the plow. Transeau termed the eastern boundary of America's great prairie ecoregion the Prairie Peninsula, with its eastern terminus in western and central Ohio. While we now know that Transeau missed some prairie, overall, his map remains quite accurate. And this map could also serve as a pretty accurate range map for the Bell's Vireo.

Here's the range map of Bell's Vireo, from Birds of the World/Cornell Lab of Ornithology. Scroll up and compare maps - I'm sure you'll see a pattern. Orange represents the breeding distribution, yellow is migratory corridors, blue is the wintering range and purple indicates year-round populations. Bell's Vireo is split into four subspecies, and I'm discussing the nominate Vireo bellii bellii, which is the subspecies, that breeds in the Great Plains and eastern prairie regions - the zones covered by the first two maps posted above. The Least Bell's Vireo (V. bellii pusillus) is an endangered subspecies breeding locally in southern California and adjacent Mexico.

The Bell's Vireos breeding in Ohio and elsewhere in the eastern limits of the prairie region are very much prairie birds. Every site that I know of regarding nesters or potential nesters in Ohio corresponds perfectly with former prairie regions. That's true of the bird in the first photo - it occupies brushy habitat in a big metropark prairie restoration towards the eastern edge of the Darby Plains, a formerly massive prairie that blanketed about 1,500 square miles in west-central Ohio. As something like 99.9% of our former prairies have been destroyed and mostly converted to corn, soybeans, and wheat, prairie birds like the Bell's Vireo and many others have declined, often alarmingly.

I was at the amazing Kankakee Sands prairie in western Indiana, on the Illinois state line, earlier this summer, when breeding birds were in full swing. It seemed that every thicket had its Bell's Vireos. The site in the photo, which had plenty of Buttonbush (Cephalanthus occidentalis), had two singing vireos, and I heard many others elsewhere in the Kankakee Sands. As one moves westward and more into the heart of their range, Bell's Vireos increase.

The Ohio enigma, as I suppose it could be called, is that Bell's Vireo was not detected in the state until 1962 - in Franklin County. That bird was followed up by another in the same county, in 1966. Both were spring migrants, in birding hotspots of the time, and not in suitable breeding habitat. The first nesting pair was discovered near Cincinnati in 1968, and there have been scores of records since, as shown on the eBird map above (which does not include all of them).

This fairly recent spate of Ohio records has been attributed to an overall eastward expansion of Bell's Vireo - a species that has declined overall in at least the last 50 years. I have to wonder if these secretive little songbirds were just overlooked. Their fidelity to former prairie regions seems undeniable. General knowledge of Ohio's prairies in the 1960's-70's was probably not as well-known as it is today. In fact, as I often see demonstrated, people generally do not have a good sense of what our habitats USED to look like, in the not-so-distant past. An understanding of former conditions can go a long way in accurately interpreting animal distribution, or lack thereof, in the present. Also, people's birding by ear skills were not as good in the earlier days of birding, I suspect. If you don't know the song of Bell's Vireo, you are going to miss all or nearly all of these thicket skulkers. My hunch is that very small numbers of Bell's Vireos have always occupied Ohio's prairie remnants but were long overlooked. As birders learned about them and how to find them, records increased.

Continued interest and action in restoring Ohio's prairies should only help Bell's Vireo. As long as attention is given to early successional shrubby habitat - a phase of ecological succession that is often given short shrift.