The ivory-billed woodpecker is one of the most elusive birds in North America. Once abundant across the southeastern United States and Cuba, this large woodpecker is now believed to be extinct or nearly so due to habitat loss. However, there have been some possible sightings in recent decades that have given hope this iconic bird may still persist in small numbers. Distinguishing between the ivory-billed woodpecker and the more common pileated woodpecker can be very challenging. But there are some key physical features, behaviors, habitat clues, and other signs that can help identify a sighting of the elusive ivory-bill.
Physical Features
There are several distinctive physical features that set the ivory-billed woodpecker apart from the similar-looking pileated woodpecker:
Size
The ivory-billed is noticeably larger, with a body length of 18-20 inches compared to 15-19 inches for the pileated. It has a wingspan of 30 inches, compared to 26-29 inches for the pileated.
Bill size and shape
The ivory-billed has a massive ivory-colored bill that is wedge-shaped and longer than its head. The pileated’s bill is less than the length of its head and black.
Plumage pattern
Both species are mostly black with prominent white markings, but the patterns differ. The ivory-billed has broad white trailing edges along the entire rear of the wings. The pileated has a narrower white stripe along the rear edge of the wings. Ivory-billed also has more extensive white along the neck and throat compared to the pileated.
Crest
Male ivory-bills have a prominent red crest that appears flattened and sloping. The pileated’s crest points upwards and looks bushier. Females of both species have less conspicuous crests.
Eye color
Ivory-bills have striking blood-red eyes. Pileateds have a darker brownish-red eye.
Feature | Ivory-billed Woodpecker | Pileated Woodpecker |
---|---|---|
Size | 18-20 in. long | 15-19 in. long |
Bill size | Massive, wedge-shaped, longer than head | Shorter than head |
Plumage | Broad white trailing edges on wings, more white on neck and throat | Narrower white stripes on wings, less white on neck and throat |
Crest on males | Flattened, sloping, red | Pointed upwards, bushy, red |
Eye color | Blood red | Darker reddish-brown |
So in terms of physical features, the much larger size, massive ivory bill, broad white markings, sloping red crest, and vivid red eyes are indicative of an ivory-billed woodpecker. The pileated is also an impressive bird, but smaller with subtle differences in plumage, bill and crest. Careful observation and size comparisons are needed to distinguish them.
Field Marks
When observing a potential ivory-billed woodpecker in the field, look for these distinctive markings:
– Broad bright white stripes along the rear edges of both the closed and open wings, extending onto the back.
– White rectangular patches on both sides of the dorsal surface, which contrast against the black plumage.
– White neck stripe extending from the cheek to the upper back. Males have a reddish crest that stands out against this white stripe.
– White underparts that may include white lines or streaks along the flanks.
– White-tipped and white-sided dorsal feathers interspersed along the back.
– White under-wing coverts contrasting with the black flight feathers.
The pileated woodpecker lacks the full white trailing edges to the wings and wide dorsal white rectangles of the ivory-bill. It shows much less white along the neck and throat. When perched, look for the large ivory-white bill, sloping red crest on males, and vivid red eyes of the ivory-billed. The pileated’s bill will look smaller with a bushier pointed crest and darker eyes.
Behaviors
Ivory-billed woodpeckers exhibit some behavioral traits that can aid in identification:
– Fly steadily with stiff, shallow wingbeats unlike the undulating flight of pileateds. Ivory-bills have been described as flying like a duck.
– Perch upright vertically on tree trunks, often with the bill pointed skywards. Pileateds perch more horizontally.
– Lean horizontally along branches in a distinctive posture when foraging.
– Occasionally hover briefly before striking a target. This is rarely done by pileateds.
– Make very loud double knocks that can be heard at great distances. The second knock comes immediately after the first.
– Excavate rectangular-shaped cavities in dead trees for nesting and roosting. Pileateds make more oval-shaped cavities.
– Feeding signs like large rectangular holes chiseled into trees may indicate the work of an ivory-bill. Pileateds make smaller more rounded holes.
So while foraging, listening for the loud double knocks, watching for brief hovering, and looking for very large rectangular holes excavated in trees can provide evidence that it may be an ivory-billed woodpecker. The pileated is not known to exhibit these behaviors regularly.
Habitat
Ivory-billed woodpeckers have very specific habitat requirements that differ from the more generalist pileated woodpecker:
– Occupies mature bottomland hardwood forests, especially swampy areas with standing dead trees (snags).
– Favors forests with a high density of very large, old trees for foraging and nesting. Trees are often 2 feet or more in diameter.
– Prefers forests with less understory vegetation and more open midstory and canopy conditions.
– Occurs near bodies of water like swamps, bayous, sloughs, rivers, and backwater lakes. Needs easy access to water.
– Found in lowland areas below 1,000 feet elevation. Pileateds occupy both low and high elevation forests.
So a remote forest with huge old trees, open understory, proximity to water, and elevations below 1,000 feet would provide ideal habitat for ivory-bills, especially in a Southern swamp or floodplain. Pileateds can thrive in a broader range of forest types and elevations.
Habitat Feature | Ivory-billed Woodpecker | Pileated Woodpecker |
---|---|---|
Forest type | Mature bottomland hardwoods | Variety of forest types |
Tree size | Very large, old trees | Medium to large trees |
Understory | More open, less vegetation | Varied density |
Proximity to water | Swamps, floodplains, riparian areas | Can be further from water |
Elevation | Below 1,000 feet | Low to high elevation |
Evidence Needed
Given how similar the ivory-billed woodpecker looks to the more common pileated, multiple lines of evidence are needed to confirm its existence:
– High quality photographs clearly showing diagnostic features like the distinctive bill, wing patterns, crest, and plumage markings are needed. Video recordings would also be very helpful.
– Feather samples could allow DNA analysis to verify species. Finding roost sites or nest cavities with feathers would provide this.
– Audio recordings of potential double knocks and calls should be analyzed by multiple experts to confirm identity.
– Detailed sighting accounts by experienced birders familiar with both species need to be thoroughly documented and reviewed. Drawings, notes on behavior, and habitat details are important.
– Surveys of appropriate habitat, especially remote swamp forests, should follow protocols specific to ivory-bills to help detect any surviving individuals.
A verified sighting would require consensus from experts that evidence like photos, audio recordings, feathers, and encounter details match only what would be expected of ivory-bills. A single sighting alone is usually not enough given the potential for misidentification. Compelling evidence in multiple forms would be needed to confirm the iconic ivory-billed woodpecker survives.
Conclusion
Distinguishing between the probable extinct ivory-billed woodpecker and the more common pileated woodpecker is challenging but possible. Key identification points include the ivory-bill’s much larger size, massive wedge-shaped white bill, broad white markings on the wings and neck, sloping red crest on males, vivid red eyes, and behaviors like double knocks, hovering, and large rectangular tree cavities. Ivory-bills occupy a specialized swamp forest habitat unlike pileateds. Given how similar they appear, multiple forms of high-quality evidence would be needed to verify the existence of this majestic but elusive woodpecker. Any sightings should be thoroughly documented and reviewed by experts. While unlikely due to its rarity, catching a glimpse of a real ivory-billed woodpecker would be the thrill of a lifetime for any birder. With patience and knowledge of its identifying features, such an encounter remains a faint possibility.