Some Thoughts on The Ivorybill’s Decline And A Change of Plans

Jamie Hill, who has worked with the Cornell and Auburn teams, recently posted a Facebook link to a very interesting article from the September 2014 issue of Smithsonian. Ivory-billed Woodpecker aside, the piece is well worth reading, but for the purposes of this blog, the article got me thinking about reasons for the ivorybill’s decline and the possible role of the longleaf pine. These ideas are not entirely new or original with me; Lester Short went even further, suggesting that pine might have been the ivorybill’s primary habitat; Jerome Jackson devoted several pages of In Search of the Ivory-billed Woodpecker to pines, and Fangsheath of the ivorybill researchers forum has hinted at this too.

I was struck by just how congruent the historic range of the ivorybill is with the range of the longleaf pine (Pinus pilastrus). The overlap is not exact, and the pre-Columbian range of the ivorybill extended as far north as Ohio. Nonetheless, conditions in the Singer Tract were objectively quite different from what they were in many other parts of the historic range.

A recent blog post on the Tallahassee Democrat site reiterates the conventional wisdom about the species and the reasons for its decline. Author Budd Titlow writes: “Before the Civil War, when much of the southeastern U.S. was covered with vast tracts of primeval hardwood swampland, ivory-billed woodpeckers ranged from North Carolina south to Florida, west to Arkansas and Texas, and north into Oklahoma and Missouri. Then, after the Civil War, extensive logging of these old-growth swamps wiped out most of the ivory-billed’s habitat in one fell swoop.”

While there’s some truth to this history, it’s also a stereotype that’s based in large part on an imperfect reading of Tanner’s monograph and even more on Tanner’s dedication to protecting the Tract as the last remaining extensive old-growth stand in the southeast (although the Tract contained considerably less old growth than Tanner believed). Tanner’s efforts were admirable; the loss of countless acres of magnificent old-growth swamp forest was devastating environmentally and is unquestionably something to be mourned, but it seems unlikely that the destruction of these forests was the primary cause for the ivorybill’s decline.

The species was known to be disappearing by 1890 or even earlier, and Chester Reed’s 1906 Bird Guide to Land Birds East of the Rockies stated that the birds were restricted to isolated parts of Florida and possibly to “Indian Country” (Oklahoma). In The Travails of Two Woodpeckers, Noel Snyder, who attributes the decline primarily to hunting, points out that intensive logging of bottomland hardwoods began between 1890 and 1900. Logging of pine forests began considerably earlier, and these forests were severely fragmented, even before the Civil War. Snyder reads the early record (I think selectively) as indicating that ivorybills strongly preferred bottomland hardwoods and seldom used pines, in contrast to the Cuban ivorybill and the Imperial.

Jackson takes a different view, citing multiple references to the use of pines for feeding and nesting. Where Snyder reads Alexander Wilson’s early account as reflecting a preference for “swamps and bottomlands”, Jackson reads him as describing the preferred Carolina habitat as “a mosaic of baldcypress swamp and pine uplands, similar to the habitat in Florida”. Jackson goes on to suggest that, “It appears . . . that ivory-billed woodpeckers will inhabit both hardwood forests of river bottoms and pine forests of higher elevations, particularly old growth forests supporting healthy populations of beetles. They seemed to do best at the interface of these forest types, taking advantage of the resources of each.” (Emphasis added).

This meshes well with what Allen and Kellogg observed in Florida in 1924; the birds nested and roosted in cypress and were observed and photographed foraging in open pine forest. The Lambs’ limited observations in Cuba suggest something similar, a preference for roosting in pines but an equal division between pines and hardwoods for foraging.

Thus, it seems possible that the Singer Tract was actually suboptimal habitat for the ivorybill, since it contained no pine and little cypress. I’m also led to suspect that habitat fragmentation, rather than habitat loss may have been central to the decline of the ivorybill, with hunting as one of several other contributing factors. This fragmentation actually began well before the Civil War, but it accelerated with the post-war destruction of the longleaf pine forests, followed by the logging of the bottomlands. I’m personally convinced that the species beat the odds and survived, using one or both of the strategies discussed in this post. I wonder whether some of the modern search efforts have focused excessively on the bottomland hardwood model and not enough on areas where there’s an interface between forest types.

On a different note, I had planned to make my final trip to our search area for the season during this week and next. Water levels are very high right now, so I’ve decided to postpone until late July. Better to endure the heat and humidity than to be unable to move around in the woods.

Advertisements

Fun With a PIWO

On the morning of the last day of Mark’s last visit, April 26, 2015, the forecast (and more importantly the doppler confirmed it) was terrible, and Mark had a terrible head cold and or allergy issue going on. He was feeling terrible! However, earlier that week he had brought in an interesting photo of a clearly active, freshly constructed cavity that was approximately 65 meters from the road he spotted it from. It didn’t take a lot of persuading to get him to agree to go with me the morning of the 26th. While we both expected the cavity (for a number of reasons, in spite of its apparent shape) to house a Pileated Woodpecker or PIWO, the shape was intriguing (from the road, anyway) enough to make it worthwhile to see what popped out the next morning. We arrived at daylight on the 26th. I strolled quietly out to about ten yards from the cavity tree. Mark, with his bigger lens stayed with the truck. I played a Pileated Drum, followed by a “scolding” “Kuk” series. Immediately, the male PIWO pictured below popped his head out. This is Mark’s best result – the light, and angle was bad and the ISO makes the pic quite grainy. Mark PIWO

This is the best one of a series of pics taken by me at the same time Mark took the one above. PIWO cavity head

When he flushed, I tried several times to get a photo or two on the wing. This is the only one where he was in the frame: Flying PIWO

Then, he perched in a nearby tree, scolding.

Perched PIWO

I’ve never noticed a PIWO doing that with its crest before. Interesting… After scolding me for a bit, he circled around and flew off – likely to check on a nearby mate. Having bothered him enough for the day, I eased back to the truck and Mark and I headed home. These poor photos are the best we could do – with a bird we fully expected to be there and good open shooting. The point being made is – birds are difficult to photograph under the best of conditions. The reason I wanted to do a post on it? I wanted to share a cool moment in our efforts with our readers. Hope y’all enjoy… Frank