SPECIES

Ivory-billed Woodpecker Campephilus principalis Scientific name definitions

Jerome A. Jackson
Version: 1.0 — Published March 4, 2020
Text last updated January 1, 2002

Breeding

Phenology

Few data to establish patterns. Species probably nested in at least 12 states from N. Carolina, Kentucky, and Missouri, south to the Gulf Coast and west to Texas and Oklahoma. Yet for all the specimens we have—many if not most of which were shot at the nest—we have nest records from only 4 states. Tanner (Tanner 1942bb) listed 14 nest records from Florida, 3 from Georgia, 16 from Louisiana, and 2 from e. Texas. Of those listed by Tanner, nest record from near Tarpon Springs, FL, listed as 17 Mar 1880, should be listed as 17 Mar 1887 (Scott Scott 1888c, Scott 1903). Nest listed by Allen for Lafayette Co., FL, is same one correctly listed by Tanner for Pumpkin Swamp, Dixie Co., FL, on the same date (19 Apr 1893). Arthur Wayne collected 3 eggs from that nest (letter from E. B. Chamberlain to Jim Tanner, 20 Aug 1941).

Earliest nest record is an adult reported incubating on 20 Jan 1880 in w.-central Florida (Scott 1881, not 1888 as cited in Tanner 1942bb). While Tanner accepted Scott's record, it is exceptionally early, and Scott's mention that this bird was incubating might have meant only that it was shot at a cavity. Scott makes no mention of seeing or collecting eggs, nor does he mention collecting a male at the nest. It seems highly likely that he would have collected the male if it had truly been a nest, since the nest cavity is the male's roost cavity, and he shares incubation during the day. On the other hand, R. D. Hoyt (Hoyt 1905) found 2 eggs in a nest near Clermont, Lake Co., FL, on 15 Feb 1905 and he noted that incubation was well under way. On 9 Mar, there was a second nest about 70 m from the first, again with 2 eggs. This was believed to be a renesting effort; cavity excavation and laying at the second nest had taken place within about 20 d.

Hoyt (Hoyt 1905) reported that, in Florida, nest-cavity excavation (building) took place in late Jan, eggs normally laid by 10 Feb, and young left nest in Apr. This scenario fits fairly well with the generalization I presented for North American woodpeckers that cavity excavation takes about 2 wk, laying takes 2–5 d (1 egg/d), incubation lasts about 2 wk, and young fledge in about 28–30 d (Jackson 1976b). Because Ivory-billeds are larger, their nestling life might be slightly longer than that of smaller species, but I see no evi-dence that the length of a successful nesting effort—from cavity excavation to fledging—differs greatly from that of other woodpecker species. Pileated Woodpeckers, for example, typically fledge at 24–31 d of age (Bull and Jackson 1995).

Initiation of nesting begins slightly earlier to the south in many species, but data supporting latitudinal variation in timing of Ivory-billed nesting are weak. In s. Florida, Scott (Scott 1892c) mentioned that Ivory-billeds bred in early Feb. In w.-central Florida, eggs by about mid-Feb. In ne. Louisiana, Tanner also had small young as early as 17 Feb but as late as 10–13 May. Latest egg date: clutch of 3 eggs found on 19 May 1892 (a second clutch) at Avery Swamp, LA, by E. A. McIlhenny (Allen and Kellogg 1937). Beyer (Beyer 1900b) found a well-feathered nestling in Louisiana in Jul 1899. Tanner also noted a range of at least 2 mo be-tween fledging of earliest young and fledging of latest. Such a range of dates for eggs and young almost certainly includes renesting efforts, but there is no firm evidence that Ivory-bills ever produced two broods/season.

Nest Site

Selection

At least 6 of 35 nests reported in Tanner 1942bb were in dead trees. In Louisiana, E. A. McIlhenny (in Bendire 1895) thought Ivory-billeds preferred partly dead trees, but noted that they always nested in the dead part, never where there was gum flow, but also never where there was extensive rot. Excavation of a cavity in sound wood is a difficult and time-consuming task that woodpeckers generally avoid. They take advantage of wood softened by wood-decaying fungi, but probably not extensively rotted wood, which provides easy access to predators. Ridgway (Ridgway 1898b), Allen and Kellogg (Allen and Kellogg 1937), Allen (Allen 1939b), Tanner (Tanner 1941, Tanner 1942bb), and Dennis (Dennis 1948a) provide photos of nests.

In a live or dead tree, nest site generally in a dead stub or below a dead stub. Such stubs—broken tree or branch—expose a cross-section of wood to rain and heavy dew, hastening fungal decay and thus allowing easier excavation of nest and roost cavities. Other benefits from excavating cavities below a branch or stub: (1) help shield cavity entrance from sun and rain; (2) shade cavity entrance, making entrance more difficult to detect; (3) may provide an avenue for fungi to enter the tree and soften the heartwood, thus making it easier for the woodpecker to excavate a cavity.

Audubon's (Audubon 1842: 216) observations were astute: “The birds pay great regard to the particular situation of the tree, and the inclination of its trunk; first because they prefer retirement, and again, because they are anxious to secure the aperture against the access of water during beating rains. To prevent such a calamity, the hole is generally dug immediately under the junction of a large branch with the trunk.”

Microhabitat

In or along edges of dense swamps (Florida; Scott 1903, Bailey 1925c). Hoyt (Hoyt 1905) described a Florida nest site as being in the heart of a baldcypress swamp with fallen timber scattered around and any ground not covered with water densely covered with myrtle (likely Myrica sp.) and bay (perhaps Persea sp.) bushes.

Site Characteristics

Tanner (Tanner 1942bb) summarized reports of at least 35 nests and general mention of others. These included at least 12 species of trees used as nest sites. Eight of the nests were reported in bald- cypress, 2 in pines, 2 in red maple, 4 in oak species (including one each in Nuttall oak and overcup oak). Other trees reported as used for nests included one nest each in bay, white elm, sweet gum, tupelo (Nyssa sp.), ash, hackberry, and cabbage palm. Audubon suggested that nests were generally in ash or “hagberry” (= hackberry, Celtis) While the range of tree species used may be meaningful, the relative use of the various species is perhaps not so useful because of the small sample. Many nests were described as being in baldcypress (Scott 1903, Hoyt 1905), but Scott (Scott 1881) said that palmetto trunks were also commonly used. Unfortunately, in many cases we do not know if the tree was live or dead, how big it was, or where the nest was relative to the lowest branches. Such is typical of the descriptions available.

In Cuba, all but one known roost/nest cavity were in pines; exception was a roost hole in a hardwood (ocuje; Lamb 1957).

Nest

Nest Characteristics

Cavity-Entrance Orientation. One recorded. Photos and descriptions indicate most cavities opened in direction nest limb leaned. This characteristic, common to woodpeckers and other cavity-excavating birds, reduces potential for cavity to fill with rainwater and may shelter cavity to some extent from aerial predators.

Nest Height. Ranged from about 4.6 m (15 ft) to >21 m (70 ft); most averaged >9 m (30 ft; Tanner 1942bb, JAJ data from specimen labels).

Vegetation Near Cavity Entrance. In some woodpecker species, such as Red-cockaded, authors (e.g., Jackson 1994b, Conner et al. 2001a) have suggested that the birds avoid sites where vegetation comes close to cavity entrance, arguing that such vegetation might facilitate predator access. This apparently not always the case with Ivory-billeds. Beyer (Beyer 1900b) found a nest entrance nearly obscured by a poison-ivy vine, and Tanner (Tanner 1942bb), after replacing a nestling in its nest, pruned a branch that was obscuring his view of the nest.

Nest-Entrance Shape, Dimensions. Apparently oval—slightly taller than wide (e.g., Tanner 1942bb; Louisiana); measurements of cavity entrance: 10.8 cm (4.25 in.) high, 9.8 cm (3.875 in.) wide (Beyer 1900b; Louisiana). Phelps (Phelps 1914: 99; Florida) described 2 nest entrances as “oblong in shape, the height being to the width in about the ratio of three to two.” Lamb (Lamb 1957; Cuba) gave width of 2 cavity entrances as 15.6 and 14.6 cm (6.1 and 5.8 in.); larger cavity was roost of a female and the cavity reportedly used by both male and female as a roost; smaller cavity apparently never used by the species. Characteristic oblong shape of Ivory-billed cavity entrances (which can also be seen on many Pileated Woodpecker cavities) may be adaptive in accommodating the entering or departing bird's crest (JAJ).

Construction Process

No descriptions. Audubon (Audubon 1842) and Thompson (Thompson 1896) indicated sexes shared nest-cavity excavation. E. A. McIlhenny (in Bendire 1895) suggested female did all nest-cavity excavation, while male watched and chipped bark from nearby trees. Ivory-billeds not only stripped bark from trees during foraging, but also seemed to characteristically strip bark for a few meters below their nests (Phelps 1914).

Nest Depth and Width/Diameter. Tanner (Tanner 1942bb) provides a good summary of Ivory-billed nest dimensions and a clear diagram of how dimensions were measured. His diagram should be a standard used for describing cavities of other species. Dimensions of nest cavities excavated in 3 consecutive years by the same pair of birds in Louisiana included the following: entrance hole ranged from 10.2 to 12.1 cm wide × 12.7–14.6 cm high; depth of cavity (roof to floor) from 44.5 to 63.5 cm; inside diameter at widest point from 15.2 to 21.6 cm × 22.9 to 26.7 cm; and diameter of stub at nest ranged from 33 to 35.6 cm. In Cuba, Lamb (Lamb 1957) reported a roost cavity used by a female and reportedly later by both a male and female as having an inside diameter of 25.4 cm (10 in.) and a depth (from “entrance” [bottom, top, or center un-known] to bottom of cavity as 32.1 cm [12.625 in.]). See also Thompson 1889 and Beyer 1900b for dimensions less well defined and probably less accurate.

Thompson (Thompson 1889: 26–27) also described Ivory-billed cavities as being “jug-shaped” (I interpret this as “a long neck with an expanded chamber below”), as opposed to “a gradually widening pocket” as found in the Pileated Woodpecker. The description for the Pileated cavity fits cavities I have seen; shape of Ivory-billed cavities may have varied with cavity tree conditions.

Microclimate

No information.

Maintenance Or Reuse Of Nest Cavities, Alternate Nests

Most woodpeckers make use of a cavity for only a single season or year. Bailey (Bailey 1925c) suggests this was true of Ivory-billeds as well, although, like other woodpeckers, nests in subsequent years were often nearby, even in same nest tree. In Cuba, a nest cavity was apparently used for 2 consecutive years (Lamb 1957). Scott (Scott 1903) suggested that a nest he found near Tarpon Springs, FL, had been used as a nest the previous year; he was guessing on the basis of the 35.7-cm (14 in.) depth of the cavity.

Eggs

Because of their rarity, Ivory-billed Woodpecker eggs were quite valuable during the heyday of egg collecting in the late 1800s. As a result, some unscrupulous individuals tried to pass eggs of the Pileated Woodpecker and other species for those of the Ivory-billed. Known Ivory-billed eggs are listed in Kiff and Hough 1985 .

Shape

Ovoid; “more oblong in shape and more pointed” than are eggs of Pileated (Baird et al. 1905: 499).

Size

Two eggs collected in Lake Co., FL, 16 Feb 1905 (set 6856-2, Western Foundation of Vertebrate Zoology; reported as collected on 15 Feb 1905 in Tanner 1942bb) measure 3.73 * 2.75 cm and 3.63 * 2.72 cm (JAJ). Hoyt (Hoyt 1905) reported measurements of this same clutch as 3.71 * 2.77 cm, 3.63 * 2.72 cm (1.46 * 1.09, 1.43 * 1.07 in.), and a second clutch laid by the same pair following removal of the first as 3.63 * 2.72 and 3.63 * 2.74 cm (1.43 * 1.10, 1.43 x 1.08 in.). Baird et al. (Baird et al. 1905) reported 1 egg (U.S. National Museum [USNM] #16196) from near Wilmington, NC, as being 3.43 * 2.41 cm (1.35 * 0.95 in.).

Mass

No data.

Color

Shiny white, probably somewhat translucent when fresh, as are other woodpecker eggs (JAJ). A “highly polished porcelain whiteness” (Baird et al. 1905: 499).

Surface Texture

Smooth, glossy (JAJ).

Eggshell Thickness

No information.

Clutch Size

Reported clutch sizes: 1–6 eggs. Nine clutches (including 2–4 eggs each) tallied from egg collections, and the literature averaged 2.9 eggs/clutch (Tanner 1942bb). Tanner mentions, but did not include, a clutch of 5 eggs reported by Thompson (Thompson 1889) for a Florida nest, and J. H. Fleming's catalog at the Royal Ontario Museum suggests he obtained a clutch of 5 Ivory-billed eggs that were originally collected on 15 May 1901 in the “Florida Everglades” for J. J. Ryman. Tanner also did not include the 1 egg from N. Carolina that is mentioned in Baird et al. 1905, perhaps because it might not have represented a completed clutch. Although sufficient details not provided to document a 1-egg clutch, Tanner's own data indicate only a single young at each of 3 nests, although a single young does not necessarily mean a 1-egg clutch. Addition of four 1-egg clutches and two 5-egg clutches to those tallied by Tanner would bring the mean clutch size to 2.7 eggs. Wilson (Wilson 1811) reported that Ivory-billed Woodpeckers usually produced 4, sometimes 5 eggs. Audubon (Audubon 1842) reported that the first clutch “usually” included 6 eggs, but provided no details. Tanner (Tanner 1942bb) suggested nests earlier in the season had fewer eggs, but sample sizes are small.

Egg-Laying

No data, but known woodpeckers generally lay eggs at 1-d intervals (JAJ).

Incubation

Onset Of Broodiness And Incubation In Relation To Laying

No data; likely begins shortly before laying of last egg, as in other woodpeckers (e.g., see Jackson 1994b, Bull and Jackson 1995, Dobbs et al. 1997).

Incubation Patch

No data; likely to occur on both parents, as in other woodpeckers.

Incubation Period

No data on either onset of incubation or incubation period. Tanner (Tanner 1942bb) suggested incubation period of about 20 d, but probably incorrect. Woodpeckers in general have short incubation periods; e.g., Red-cockaded about 10–11 d (Jackson 1994b), Pileated 15–16 d (Kilham 1979a), similar-sized Black Woodpecker (Dryocopus martius) 12–14 d (Cramp 1985a).

Onset Of Incubation

No information; likely begins shortly before laying of last egg as suggested for other woodpeckers (see above).

Parental Behavior

Shared by both parents; in Louisiana at several nests, adults exchanged position at the nest about 8 times/d (Tanner Tanner 1941, Tanner 1942bb). Nest in roost cavity of breeding male; male roosts with eggs and young at night; female roosts in a separate cavity.

Hardiness Of Eggs Against Temperature Stress; Effect Of Egg Neglect

No information.

Hatching

No information.

Young Birds

Condition At Hatching

Presumed altricial and nidicolous; no description of hatchlings.

Growth And Development

Known brood sizes 1–4 young (Tanner 1942bb). No nests followed from eggs through fledging, thus nothing known of possible brood reduction. Late-hatched young of other woodpeckers often die.

Early mention of nestlings was made by collectors who were looking for eggs or who were interested in skins of adult birds. If they climbed to a nest in search of eggs and found nestlings, they were disappointed, usually did not bother to comment on their find, and in some cases may have destroyed the young in hope that it would induce the adults to renest so that they could obtain fresh eggs. We do find a few descriptions of young. Scott (Scott 1903: 269) found a nest near Tarpon Springs, FL, with a chick he described as about one-third grown, slightly feathered, eyes not yet open, feathers of first plumage beginning to cover the down, and exactly the same coloration as the adult female. Occurrence of closed eyes as feathers of first plumage emerge is as in other woodpecker species.

In other woodpeckers, such as similar-sized Pileated (Hoyt 1944), by about 7 d after hatch, feather tracts are dark and just tips of feathers may be poking through. By day 10, tips of many feathers have emerged and opened, eyes usually just beginning to open. Assuming a similar rate of development in Ivory-billeds, Scott's nestling would have been about 9–10 d old, perhaps 11–12 d. Contrary to Scott's de-scription, no woodpeckers known to have natal down, and it is highly unlikely that Ivory-billed was an exception. First plumage of woodpeckers (and other birds) is characteristically weaker, lacks iridescence that adults might have, and is more fluffy in appearance as a result of the presence of fewer barbs within the feather web. More durable plumage not needed since this first plumage is replaced quickly, often beginning before young leave nest.

Molt Into Mesoptile Plumage

No data.

Control Of Body Temperature

No data.

Parental Care

Brooding

By both parents; begins at hatching and is nearly constant for first 4 d; decreases in frequency slowly through about day 10, infrequent during the day thereafter. Male broods at night (Tanner 1942bb).

Feeding

From Tanner Tanner 1941, Tanner 1942bb (Louisiana). By both parents about 30 feedings/d early in nestling life, decreasing to about 15/d later. From one observation period to another, the sex bringing the most food differed, but overall contributions of sexes were close; e.g., 77 feedings by males and 82 by females. Feedings peaked early in morning and again in late afternoon; lull at midday.

Nest Sanitation

Nest generally clean, even after nestlings had fledged (Beyer 1900b). Tanner (Tanner 1942bb) observed only the male removing fecal material from nest; sometimes dropped at nest entrance and sometimes carried a short distance and dropped in flight.

Cooperative Breeding

Not known.

Brood Parasitism by Other Species

Not known to occur in this species.

Fledgling Stage

Departure From Nest

About 5 wk after hatching (Tanner 1941).

Growth

No quantitative information. See discussion of bill maturation, below.

Association With Parents Or Other Young

Fledgling dependency on parents seems to be exceptionally long, perhaps ≥1 yr; Tanner (Tanner 1942bb) noted a banded juvenile male associating with its parents just prior to next nesting season.

Ability To Get Around, Feed, And Care For Self

Fledglings able to fly long distances (Tanner 1942bb) but probably not to feed in manner of adult; lengthy period needed for maturation of chisel-like bill. Comparison of bill of an adult with that of a presumed older juvenile (both specimens in Definitive Basic plumage) illustrates rounded, not at all chisel-like bill of the younger bird.

Immature Stage

Little information. Young in the Singer Tract began using a roost cavity ≥2 wk after fledging (Tanner 1941). Fed by their parents for ≥2 mo after fledging, but by 3 mo could find food on their own. A young male stayed with its parents through following nesting season, although adult female (presumably its mother) repeatedly tried to drive it away (Tanner 1941).

Ivory-billed Woodpecker Ivory-billed Woodpecker clutch, Florida.
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Ivory-billed Woodpecker clutch, Florida.

Collected Lake Co., FL. 16 Feb 1905. Ruler is 8 cm.; photographer Rene Corado

Ivory-billed Woodpecker Adult male Ivory-billed Woodpecker at its nest hole, n. Louisiana.
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Adult male Ivory-billed Woodpecker at its nest hole, n. Louisiana.

This picture of the Ivory-billed Woodpecker, taken by Arthur Allen (founder of the Cornell Lab of Ornithology) in the 1930s, is still one of the best photographs available of this rare phantom. Seen here outside its nest hole in northern Louisiana.

Recommended Citation

Jackson, J. A. (2020). Ivory-billed Woodpecker (Campephilus principalis), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.ivbwoo.01