Papers that present conclusive evidence for the persistence of the Ivory-billed Woodpecker:
Paper #1 discusses conservation issues and all of the evidence.
Paper #2 discusses double knocks, wingbeats, and some of the evidence.
Paper #3 discusses audio recordings and some of the evidence (supplemental material).
Presentations of the evidence in lecture format.
Drone video footage of Ivory-billed Woodpecker habitats.
Photos and video footage that were obtained during sea trips to the north of
Norway (2014) and Alaska
(2016 and 2017).
Drone video footage that shows the approaching shadow of the 2017 eclipse.
Ivory-billed Woodpeckers in the Pearl River Swamp
In April 2005, the most exciting news in the history of conservation came from Arkansas, where a team led by Cornell University
had a series of Ivory-billed Woodpecker sightings. There had been many sightings since the 1940s, including David Kulivan’s report of a pair in the Pearl River
along the southern border between Louisiana and Mississippi in 1999, but they usually lacked evidence or follow-up sightings to back them up. The news from Arkansas motivated successful searches in the Choctawhatchee River in Florida
(led by Auburn University) and in the Pearl River (documented at this website). Having heard “kent” calls on the Mississippi side of the Pearl River in February 2000, where
unusual bark scaling was discovered several years later, I knew that Kulivan’s report was legitimate.
Between November 2005 and June 2013, I spent several months per year searching for Ivory-billed Woodpeckers in the Pearl River. Most of the searching involved kayaking and hiking through appropriate habitat, but I spent some time observing from tall cypresses that provide unobstructed views over the treetops. During a five day period in February 2006, I had five sightings,
heard kents on two occasions (once coming from two directions at the same time), and obtained
video footage of a perched Ivory-billed Woodpecker. A short distance up the same bayou in March 2008, I was keeping watch from one of the observation trees and obtained
video footage of an Ivory-billed Woodpecker in flight. While working with Geoff Hill’s search team in the Choctawhatchee River in January 2007, I had an encounter with a pair of Ivory-billed Woodpeckers and obtained
video footage of a double knock and spectacular swooping flights that must be the types of flights that inspired John James Audubon to describe the flight of this bird as “graceful in the extreme.” Several events in the videos show field marks, flights, behaviors, and other characteristics that are consistent with the Ivory-billed Woodpecker but no other species. Nobody has proposed a plausible alternative explanation for any of the events. Papers and lectures that discuss this evidence may be accessed in the Quick Links section above. Additional information is available at the following links:
Daily logs for the 2006,
2011, 2012, and
2013 search seasons and for
visits after 2013.
of sightings, sights and sounds from the Pearl River,
photo gallery, and digital artwork.
Cartoons based on the Ivory-billed Woodpecker’s ability to frustrate bird watchers and
supposed need for old growth forest.
Alaska Sea Trip - Fall 2017
During the fall of 2017, I participated in a sea trip to the north of Alaska and obtained lots of
photos and video footage. The videos may also be accessed in
this playlist on YouTube. The trip began in Dutch Harbor on October 18 and ended in Seward on November 8. This map shows the trip back to the south.
I obtained photos of the aurora from the ship with a DJI Osmo+, a camera with a gimbal that can be used for long exposures on a moving platform. Among the highlights of the trip were observing sea ice, the auroras, and the amazing flights of albatrosses, going through the Unimak Pass, and seeing for the first time the Alaska Peninsula, Kodiak Island, the Kenai Peninsula, Seward, Denali, and Anchorage.
This image of an apparent Ivory Gull is from the 11:44 mark in this video (the bird is flying from left to right near the top edge of the picture).
Alaska Sea Trip - Fall 2016
During the fall of 2016, I participated in a sea trip to the north of Alaska and obtained lots of
photos and video footage. The videos may also be accessed in this playlist on YouTube. As shown on this map, the trip began in Nome on October 15 and ended in Dutch Harbor on November 11. Most of the trip was above the Arctic Circle, and we got up to 75° N. Some of the highlights of the trip were a Gyrfalcon, an Ivory Gull, and twenty-one Ross’s Gulls that were in migratory flights to the west. Some of the video footage was obtained with a DJI Phantom 3 Pro drone, but it was usually too windy for it.
Norway Sea Trip - Winter 2014
During the winter of 2014, I participated in a sea trip off the coast of Norway and obtained lots of
photos and video footage. The videos may also be accessed in
this playlist on YouTube. As shown on this map, the trip began in Ålesund on February 18 and ended in Tromsø on March 9. Most of the trip was above the Arctic Circle, including several days above the northernmost tip of Norway up to nearly 72° N. Only a few people went ashore during a brief stop at Honningsvåg, but it was interesting to see that town from the ship. The video footage was obtained using bino-cam, which consists of a video camera mounted on binoculars. The binoculars provide a better image than the viewfinder and make it easier to get the camera on a bird. I saw a gull that seemed different from all of the common species that were seen regularly during the trip and suspected it was an Ivory Gull while watching it through the binoculars. It was exciting to see flocks of alcids with stunning Arctic scenery in the background. I never got tired of watching fulmars in flight. The northern lights were indescribably amazing on some nights, with some of the glowing green arcs passing directly above and extending from one horizon to the other.
Cruise to Alaska - May 2014
During the last week of May 2014, I obtained lots of photos and video footage during a sea cruise from Seattle to Alaska with Holland America.
The videos may also be accessed in this playlist on YouTube. I saw lots of seabirds during the transit from Seattle to Juneau, including several Black-footed Albatrosses, lots of Leach’s Storm Petrels, a few Fork-tailed Storm Petrels, several unidentified Shearwaters (some with white underwings and some with dark underwings), and many alcids. I saw lots of whales and other sea mammals at various points during the trip. My favorite part of the trip was going up Mt. Roberts in Juneau and seeing Rock Ptarmigans. I was expecting the ptarmigans to be in breeding plumage and was initially taken aback by the stunning white plumage. I heard one of them calling and the video shows the field marks well enough for positive identification. I was amazed by the flight and rapid bursts of wingbeats of that species. It was difficult to track a pair through the viewfinder of the video camera as they passed in front of patches of snow during a meandering flight. There was an amusing photo-bombing by a Bald Eagle during the filming of a singing Fox Sparrow. I was blown away by the beauty of Glacier Bay. It was the first time I was able to really study the Arctic Tern. I was amused to see a Black-legged Kittiwake resting on a small iceberg.
Eclipse - August 2017
I watched the eclipse of August 21, 2017, near the Boysen Reservoir just to the north of Riverton, Wyoming. My primary objective was to film the approaching shadow with a drone, but I brought along a Sony HDR-HC5 video camera. Since totality would last for only a few minutes, I decided on a plan that would allow me to start the drone and video camera and then focus on enjoying the spectacle. Ten minutes before the start of totality, I launched the drone and left it hovering at an altitude of 120 meters. Immediately after the start of totality, I aimed the video camera at the Sun and left it recording from a tripod. As I had hoped, the
drone video shows the approaching shadow. I have never seen a film that really captures the splendor of how an eclipse appears to the eye, but the other video might have been better if I had taken the time to adjust the exposure and zoom. During the partial phases of the eclipse, there were obvious drops in temperature and light, as illustrated in these photos.
Arizona - June 2015
During a visit to Arizona, I spent a day each in the Chiricahua and Huachuca Mountains in
the southeastern corner of the state and also visited Monument Valley and
Petrified Forest National Park. Some photos of the
gorgeous scenery are posted here. I had a bit of an adventure during a hike around Carr Peak. On the
way up a steep trail to Bear Saddle, I got severe cramps in my thighs and had to use up most of my fluids in order to stop them. I was
beyond the half-way point of the hike and decided to keep going. When the trail got steeper and the cramps returned, I decided to turn
back. The trail ahead was uncertain, and I knew there was a stream with water on the way back. I wouldn’t have
made it out of there if not for that stream.
Colorado - June 2014
I spent several days in Colorado at the end of June 2014. I obtained photos and video footage of flowers and the glass artwork of Dale Chihuly at the Denver Botanical Gardens and of wildflowers, wildlife, and scenery in the mountains in Golden Gate Canyon State Park and Rocky Mountain National Park.
1000 Islands - August 2015
In August 2015, I took a cruise out of Kingston, Ontario, that
sailed through the 1000 Islands and made stops at Upper Canada Village,
the observation tower near the international bridge, and
other locations. Some photos are posted
Solving Puzzles with Group Theory
I didn’t have much interest in Rubik’s Cube when it first came out, but then it occurred to me that it’s a fascinating application of group theory. It was 1982, and I had recently been introduced to that topic in an algebra class at MIT. It didn’t take long to figure out how to solve it using commutators, conjugates, and the cycle notation. I was hoping that someone would generalize it to the dodecahedron. Such a puzzle, which is known as the Megaminx (shown above), was already available at the time, but I didn’t find out about it until decades later. I have posted a lecture on
solving puzzles using group theory. FORTRAN codes for solving these puzzles on the screen are available for download.
Football Power Rankings
Bird Watching Trip Reports
Photos from Manu National Park: Peruvian Amazon
Iguazu Falls: Near the Argentina, Brazil, Paraguay border
Photos from the Four Corners area
Photos from Big Bend National Park
Photos from Yellowstone National Park
Favorite Photo: Rio Marañon (a branch of the Amazon) near Balsas, Peru
Wakefield Park: A Hotspot for Mourning and Connecticut Warblers
Venus transits the Sun (June 8, 2004)