Pileated Woodpecker Research Articles

Persistence, changes and robustness of nest webs along a latitudinal gradient in the Canadian boreal forest

IntroductionIn eastern Canada, the boreal forest is associated with an important latitudinal shift in forest composition and structure, which occurs in the transition between the mixed southern boreal forest and the coniferous northern boreal forest. Along this transition, upland mixedwood stands with large deciduous trees (important for cavity-dependent vertebrate species) are gradually replaced by forests with smaller conifer trees, primarily black spruce (Picea mariana). Concomitantly, the availability of lowland forests flooded by the American beaver (Castor canadensis), which can provide adequate conditions for tree-cavity users, is also decreasing.MethodsWe hypothesized that this latitudinal gradient would bring important changes in the functional diversity and network structure of vertebrate cavity-using communities. Along this latitudinal gradient we used a nest web approach to analyze the structure and robustness of networks of cavity users in upland forests and in lowland forests flooded by beavers.ResultsDespite their low availability in the northern forest region, we found that mixedwood stands persisted throughout the boreal forest in being the main drivers of nest webs network structure of upland forests whereas old black spruce stands contribution was low. In lowland forests, beaver ponds harbored nest webs with a rich and complex structure in both forest regions. Species removal simulations revealed that across our latitudinal gradient upland and lowland forest nest webs responded differently. In upland forests, the removal of trembling aspen and the Pileated Woodpecker (Dryocopus pileatus) caused the highest proportions of secondary extinctions, showing low robustness of nest webs given that these two species were highly connected to the other species. Contrastingly, nest webs in beaver ponds were more robust mainly because excavator species used a higher diversity of tree species despite the removal of the Northern Flicker (Colaptes auratus) which induced numerous secondary extinctions. The Pileated Woodpecker remained the pivotal species across the two forest regions in upland forests whereas the Northern Flicker became the main large cavity provider in beaver ponds across the latitudinal gradient.DiscussionWe discuss how mixedwood forests and beaver ponds, which are key habitat types for the cavity-using vertebrate community across our latitudinal gradient, should be maintained and protected in landscapes under industrial timber harvesting.

An ecological perspective on the temporal variation in Pileated Woodpecker ( Dryocopus pileatus ) drumming behavior in Alberta, Canada

An ecological perspective on the temporal variation in Pileated Woodpecker ( Dryocopus pileatus ) drumming behavior in Alberta, Canada

Update on the Ivory-billed Woodpecker (Campephilus principalis) Scandal

The Ivory-billed Woodpecker (Campephilus principalis) is an elusive bird that has repeatedly been feared extinct only to be rediscovered during the past hundred years. The most recent rediscovery, which took place in Arkansas, was announced in an article that was featured on the cover of Science in 2005. Despite published reports of sightings in Florida and Louisiana in the years that followed, the issue became controversial when nobody managed to obtain a clear photo and critics attacked relatively weak video evidence that was presented in the original article. The issue began to develop into a science scandal when the critics used specious arguments to delay the publication of the strongest evidence, which consists of three videos that were obtained during encounters with birds that were identified in the field as Ivory-billed Woodpeckers and that show field marks, body proportions, flights, and other behaviors that are consistent with that species but no other species of the region. The scandal culminated in a decision by the U.S. Fish & Wildlife Service to declare the species extinct in 2021, which was made without addressing the strongest evidence. An update is given here on recent developments. The decision to declare the species extinct was based on a five-year review of evidence for persistence. During an interview, it came to light that the person who performed the review was unaware of basic facts about the strongest evidence. Evidence that was obtained at another site in Louisiana [Latta et al., “Multiple lines of evidence suggest the persistence of the Ivory-billed Woodpecker (Campephilus principalis) in Louisiana,” Ecology and Evolution (2023)] is discussed and compared with the strongest evidence. Videos obtained with a drone on a sunny day often show white markings that do not correspond to actual field marks. It is demonstrated that a video that was purported to show an Ivory-billed Woodpecker on the basis of apparent white markings is apparently a Pileated Woodpecker (Dryocopus pileatus). The bird in that video appears to have black trailing edges on the dorsal surfaces of the wings, which are consistent with the Pileated Woodpecker, not the Ivory-billed Woodpecker. The wingbeat frequency and an upward swooping landing also seem to be consistent with the Pileated Woodpecker but are not consistent with historical accounts of the Ivory-billed Woodpecker or flights appearing in videos that contain the strongest evidence.

Woodpeckers in the city: Abundances are highest in large green spaces with complex understories

Abstract We documented occurrence and relative abundance (henceforth abundance) of five woodpecker species in 36 forested green spaces in Portland, Oregon (USA), to estimate minimum area requirements (MAR; 0.5 probability of occurrence) and to test for potential influences of green space area and type (heavily treed manicured green spaces vs. undeveloped natural forests), habitat features, and landscape composition on the abundance of woodpeckers. Abundances of all species increased with green space area. Manicured and natural green spaces did not differ in canopy cover or total basal area, but woodpecker abundances were greater in natural than manicured green spaces for all species except Northern Flickers (Colaptes auratus). Flickers and Downy Woodpeckers (Picoides pubescens) were most abundant, MAR of both were under 1.5 ha, and both were found in essentially all green spaces. Hairy (P. villosus) and Pileated (Dryocopus pileatus) woodpeckers were least abundant, and with MAR of 34 and 51 ha, respectively, exhibited pronounced area sensitivity. Red-breasted Sapsuckers (Sphyrapicus ruber) were intermediate in abundance and MAR to the 2 former and 2 latter species. The most important habitat variables associated with variation in abundance among green spaces were the contribution of deciduous trees to the canopy (Downy Woodpecker [+], Pileated Woodpecker [+], and Northern Flicker [–]), canopy cover (Hairy Woodpecker [+] and Northern Flicker [+]), and log density (Hairy Woodpecker [+], Red-breasted Sapsucker [–]). At the landscape level, lower woodpecker abundance was associated with increased urbanization (Red-breasted Sapsucker and Northern Flicker), while increasing forest cover influenced abundance of Northern Flicker (–) and Pileated Woodpecker (+). Highest woodpecker abundances were thus found in large green spaces with complex understories that were embedded in relatively undeveloped treed landscapes. Management of forested urban green spaces should prioritize needs of the area-sensitive species because ensuring their continued presence benefits the entire avian community.

Conversations as Vessels and Anchors

Conversations as Vessels and Anchors

The use of remotely sensed data to model habitat selections of pileated woodpeckers (Dryocopus pileatus) in fragmented landscapes

Light detection and ranging (LiDAR) and four-channel red, green, blue, and near-infrared (RGBI) remote sensed imageries allow an accurate quantification and contiguous measurement of vegetation characteristics and forest structures. This information facilitates the generation of habitat structure variables for forest species distribution modelling. However, applications of remote sensing data, especially the combination of structural and spectral information, to support evidence-based decisions in forest managements and conservation practices at local scale are not widely adopted. In this study, we examined the habitat requirements of pileated woodpecker (Dryocopus pileatus) (PW) in Hamilton County, Ohio, using ecologically relevant forest structural and vegetation characteristics derived from LiDAR and RGBI data. We hypothesized that the habitat of PW is shaped by vegetation characteristics that are directly associated with the availability of food, hiding and nesting resources, the spatial arrangement of habitat patches within home range, as well as proximity to water sources. We used 186 PW presence or absence locations to model their presence and absence in generalized additive model (GAM) at two scales, representing foraging and home range size, respectively. The results confirm PW’s preference for tall and large mature stands with structural complexity, typical of late-successional or old-growth forests. Besides, the crown size of dead trees shows a positive relationship with PW occurrence, therefore indicating the importance of declining living trees or early-stage dead trees within PW home range. These locations are preferred by PW for nest cavity excavation as it attempts to balance the ease of excavation and tree security. In addition, we found that PW can adjust its travel distance to the nearest water resource, suggesting that habitat fragmentation can have certain impacts on PW. Based on our findings, we recommend that forest managers should use different priorities to manage nesting, roosting, and feeding habitats. Particularly, when devising forest management and hazard tree removal plans, one needs to consider retaining enough cavity trees within high-quality PW habitat. By mapping PW habitat suitability for the study area, we highlight the importance of riparian corridor in facilitating PW to adjust to the fragmented urban landscape. Indeed, habitat improvement for PW in the study area could be achieved by conserving riparian corridors and promoting riparian forest succession along major rivers in Hamilton County. (The acronyms used in this paper are listed in Table A1 of the Appendix.)

A review of the woodpeckers (Aves: Piciformes) from the asphalt deposits of Rancho La Brea, California, with the description of three new species

A review of the piciform avifauna from the upper Pleistocene asphalt deposits of Rancho La Brea, Los Angeles, California, reveals that it comprises at least six species in five genera. We describe a new genus and species, Breacopus garretti, for the largest woodpecker, which was similar in size to the largest living North American species, Dryocopus pileatus. We recognise a new genus and species, Bitumenpicus minimus, for the smallest woodpecker in the palaeoavifauna of Rancho La Brea. We also recognise a new species of Melanerpes, M. shawi. The most common species present in the asphalt deposits is the Northern Flicker, Colaptes auratus, which is predictable because of its ground-foraging habits, which would bring it into contact with the surficial seeps of petroleum more often than those piciforms preferring an arboreal habitat. Habits of the extant species from Rancho La Brea suggest a primarily open environment, with the largest species suggesting the presence of at least scattered large trees. The piciform palaeoavifauna provides support for the hypothesis that southwestern California was a “biogeographic island,” or a region where the insular nature of the habitat promoted speciation during the late Pleistocene.

The Re-Establishment of Pileated Woodpeckers in New York City Following Nearly Two Centuries of Extirpation

Dryocopus pileatus (Pileated Woodpecker) is an endemic North American woodpecker that, following widespread declines during the mid-to-late 19th century, rebounded and has become relatively common resident throughout its range. In New York City, Pileated Woodpeckers were breeding residents until the early to mid-1800s, but were extirpated due to the city's rapid urbanization. Since the 1930s, however, the number of reports of Pileated Woodpeckers has increased dramatically in the area. Here we document the re-establishment of Pileated Woodpeckers in New York City within 2 old-growth greenspaces on Staten Island from 2015 to 2019. We further describe and validate a previously unpublished breeding attempt on Staten Island from 1989. The establishment of Pileated Woodpeckers in New York City is reflective of their ongoing colonization of urban and suburban areas throughout North America, and highlights the importance of unfragmented greenspaces within urban and suburban areas.

Predicting effects of selection cutting on avian diversity and abundance in shade-tolerant hardwood forests of central Ontario

Emulating natural disturbance (END) patterns to conserve biodiversity is often a goal of forest management but the impact of forest cutting is still controversial. We examined effects on avian assemblages of partially-cut forest stands of 1–10, 11–20 and > 45 years (cut classes) post-harvest differing in the % basal area retained as wildlife species’ habitat in 85 shade-tolerant hardwood stands in Algonquin Park, Ontario. Permutational multivariate analysis of variance indicated significant compositional differences among cut classes, after controlling for year and township (spatial variation in surficial geology and topography), both of which were also significant. Pairwise comparisons indicated significant compositional differences only between young and old stands. The difference in beta diversity (homogenization/differentiation) among cut classes was marginally significant (P = 0.066). Pairwise differences were significant between old versus mid-aged cut classes, marginally significant for young versus old cuts, and non-significant for young versus mid-aged cut classes. Six species and cavity users as a group were more abundant in > 45 years post-harvest stands than in the other two cut classes. Six species had higher abundances in younger cuts than > 45 years post-harvest cuts. Red-eyed vireo (Vireo olivaceus) showed a nonlinear response and was least abundant in 11–20 year cuts. Blackburnian warblers Setophaga fusca, black-throated green warblers S. virens and pileated woodpeckers Dryocopus pileatus increased with the density of supercanopy trees (≥ 60 cm diameter at breast height - dbh) and in the case of pileated woodpeckers more large snags (≥ 40 cm dbh). Brown creeper Certhia americana abundance increased with greater basal area of trees ≥ 25 cm dbh and ovenbird numbers were significantly related to overall basal area. Chestnut-sided warbler S. castanea abundance decreased with an increase in overall basal area and was higher in the 1–10 year cuts and American redstarts S. ruticilla decreased with an increase in basal area. Our modelling suggests that effects of selection cutting systems on the avian community may be reduced as tolerant hardwood stands become regulated and have higher residual basal areas. Current guidelines in Ontario for the retention of large, scattered conifer trees appear to meet the requirements for most, but not all, species; however, guidelines for supercanopy trees are too low. These results indicate that the END paradigm for single-tree selection cutting in tolerant hardwoods may be partially effective but requires modifications, such as retaining higher densities of supercanopy trees that would be beneficial for birds.

Gaps and Runs in Nest Cavity Occupancy: Cavity “Destroyers” and “Cleaners” Affect Reuse by Secondary Cavity Nesting Vertebrates

Many animals require tree cavities for breeding and these sites may be reused by a diversity of secondary nesters over a timespan of decades. It is unknown whether the reuse of holes changes their desirability as nest sites. We hypothesized that some species, cavity degraded the quality of holes by filling them with coarse nest material or waste whereas other species, cavity cleaners, might prolong the use of a hole by removing debris or enlarging the hole. Using data gathered during 22 years from a field study in central British Colombia, we analyzed long-term patterns of occupancy in relation to their sequential use by bird and mammal species, grouped by traits. Patterns of occupancy were variable with 49% of 875 large-sized holes (excavated by northern flickers Colaptes auratus and pileated woodpeckers Dryocopus pileatus) and 19% of 672 smaller-sized holes incorporating runs of sequential use that lasted up to 18 years. But 11-25% of cavities also had gaps of 3-13 years between occupancies. Mammals, raptors and European starlings, consistent with the hypothesis they were destroyers, occupied cavities as terminal users and before gaps more often than expected by chance. The pattern of occupancy by northern flickers was random in relation to gaps or prior use by other species so, although flickers did not target old holes to clean, neither did they avoid them. Small cavities that were renovated by flickers into larger cavities had double the reuse rate. Runs of occupancy that involved only cavity-destroying species were shorter than runs that involved periodic use by flickers, suggesting the woodpecker, through its cleaning and renovation, prolonged the use of such holes.

Roosting, reproduction, and survivorship of Pileated Woodpeckers (Dryocopus pileatus) in a suburban setting

Roosting, reproduction, and survivorship of Pileated Woodpeckers (Dryocopus pileatus) in a suburban setting

Ecosystem services and disservices of bear foraging on managed timberlands

AbstractThe literature on ecosystem services has been criticized for inadequately acknowledging culture values and for de‐emphasizing economic disservices. While economic loss due to tree damage by American black bears (Ursus americanus, hereafter bears) may negatively affect timber production, it also alters forest structure and habitat that may contribute to forest wildlife diversity, including culturally significant species. We examined the relationship between bear damage to Douglas‐fir trees (Pseudotsuga menziesii var. menziesii) and response of cavity‐nesting birds on the Hoopa Valley Indian Reservation. We measured disservices from bear damage by calculating current and future timber revenue loss, and ecosystem services by calculating forest structural complexity, abundance and diversity of cavity‐nesting birds, and woodpecker activity. Bear damage was correlated negatively with tree growth and positively with estimated timber loss. Forest structural complexity was positively correlated with bear damage, and cavity‐nester abundance and woodpecker foraging activity were positively correlated with forest structural complexity and bear damage. Pileated woodpeckers (Dryocopus pileatus) and red‐breasted sapsuckers (Sphyrapicus ruber) used bear‐damaged trees out of proportion to their availability, and pileated woodpeckers selected for more structurally complex sample units. Information from this study advances our understanding of the potential for bear foraging to negatively affect economic revenue and the trade‐offs with habitat conditions favoring other important wildlife species. Understanding the costs and benefits of bear damage can help guide management decisions vital to forest managers both on and off tribal lands.

A Cacophony of Signals: Woodpecker Sexbots, Squirrel NORAD, and Other Robotic Systems

This article discusses the author’s robotic artworks, which consider the human-made body's future as a willful entity and the nature of communication. The robots use computer vision or sound signal processing to search the world for the signals of target species and then attempt to respond through similar gestural and audible signalling. The robots are trying to communicate with the animals and, in part, allow human communion with those animals in ways that human bodies and umwelts don't allow. That human narrative stamps itself heavily onto the projects is confirmed by these becoming things like a hermaphroditic sexbot for Pileated Woodpeckers and a NORAD equivalent for Grey Squirrels.

A Cacophony of Signals: Woodpecker Sexbots, Squirrel NORAD, and Other Robotic Systems

This article discusses the author’s robotic artworks, which consider the human-made body's future as a willful entity and the nature of communication. The robots use computer vision or sound signal processing to search the world for the signals of target species and then attempt to respond through similar gestural and audible signalling. The robots are trying to communicate with the animals and, in part, allow human communion with those animals in ways that human bodies and umwelts don't allow. That human narrative stamps itself heavily onto the projects is confirmed by these becoming things like a hermaphroditic sexbot for Pileated Woodpeckers and a NORAD equivalent for Grey Squirrels.

Statistics, Probability, and a Failed Conservation Policy

Many sightings of the Ivory-billed Woodpecker (Campephilus principalis) have been reported during the past several decades, but nobody has managed to obtain the clear photo that is regarded as the standard form of evidence for documenting birds. Despite reports of sightings by teams of ornithologists working independently in Arkansas and Florida, doubts cast on the persistence of this iconic species have impeded the establishment of a meaningful conservation program. An analysis of the expected waiting time for obtaining a photo provides insights into why the policy of insisting upon ideal evidence has failed for this species. Concepts in statistics and probability are used to analyze video footage that was obtained during encounters with birds that were identified in the field as Ivory-billed Woodpeckers. One of the videos shows a series of events that are consistent with that species and are believed to be inconsistent with every other species of the region. Another video shows a large bird in flight with the distinctive wing motion of a large woodpecker. Only two large woodpeckers occur in the region, and the flap rate is about ten standard deviations greater than the mean flap rate of the Pileated Woodpecker (Dryocopus pileatus). Supplemental materials for this article are available online.

Use of suburban landscapes by the Pileated Woodpecker (Dryocopus pileatus)

ABSTRACT Urban areas continue to expand, with cities now containing more than half of the world's population. As cities grow, natural habitat is transformed, changing the face of the local biota and the resources available for it. Wherever woodpeckers are present, the cavities that they excavate provide an important ecological service that facilitates many other species. We studied how the Pileated Woodpecker (Dryocopus pileatus) uses suburban areas. From 2009 to 2013, we used radio-telemetry to determine the annual home range size and habitat use of 13 individuals in 9 suburbs that varied in their level of urbanization (ranging from 5% to 90% forest remaining). We used concentration of use and resource utilization functions to examine vegetative characteristics used by woodpeckers at relatively large (i.e. 1 km2) and more local (i.e. ⅓ ha) scales. The average home range of suburban Pileated Woodpeckers was significantly smaller than expected based on previous studies. Pileated Woodpeckers concentrated th...

Space use of suburban pileated woodpeckers (Dryocopus pileatus): insights on the relationship between home range, core areas, and territory.

Home range, territory, and core areas are concepts that have been used to describe a species' space use. However, little research has been done to understand potential spatial relationships between them. While the relative importance of different areas of the home range has been addressed with utilization distributions, there is a lack of such analysis for territories. We mapped the locations of territorial advertisements (calls and drumming) of the pileated woodpecker in suburban areas to determine a more objective, behavior-based approach to define areas of importance within territories, which we called 'highly-defended areas'. We then analyzed the relationship between such highly-defended areas and a bird's home range and territory. On average, territories represented 69.6 ± 0.06% (mean ± SE) of a woodpecker's home range, and highly-defended areas were 34.3 ± 0.03% of their home range. Highly-defended areas objectively determined the portion of the territory that was important for fitness. For example, they contained a significant proportion of the nests and roost sites of pileated woodpeckers, which are important for reproduction and survivorship. This approach could be useful to further incorporate behavior in the study of the spatial ecology of species.

Periodic and transient motions of large woodpeckers

Two types of periodic and transient motions of large woodpeckers are considered. A drumming woodpecker may be modeled as a harmonic oscillator with a periodic forcing function. The transient behavior that occurs after the forcing is turned off suggests that the double knocks of Campephilus woodpeckers may be modeled in terms of a harmonic oscillator with an impulsive forcing, and this hypothesis is consistent with audio and video recordings. Wingbeats are another type of periodic and transient motion of large woodpeckers. A model for the flap rate in cruising flight is applied to the Pileated Woodpecker (Dryocopus pileatus) and the Ivory-billed Woodpecker (Campephilus principalis). During a brief transient just after taking off, the wing motion and flap rate of a large woodpecker may not be the same as in cruising flight. These concepts are relevant to videos that contain evidence for the persistence of the Ivory-billed Woodpecker.

Abundance of chewing lice (Phthiraptera: Amblycera and Ischnocera) increases with the body size of their host woodpeckers and sapsuckers (Aves: Piciformes: Picidae)

AbstractSpecimens of five species of woodpeckers (Piciformes: Picidae) from Manitoba, Canada, were weighed and examined for chewing lice, 1998–2015: downy woodpecker (Picoides pubescens (Linnaeus), n=49), hairy woodpecker (Picoides villosus (Linnaeus), n=23), pileated woodpecker (Dryocopus pileatus (Linnaeus), n=10), northern flicker (Colaptes auratus (Linnaeus), n=170), and yellow-bellied sapsucker (Sphyrapicus varius (Linnaeus), n=239). The relationship between body mass of each host species and infestation by seven species of lice was analysed: Menacanthus pici (Denny) from all host species, Brueelia straminea (Denny) from Picoides Lacépède species, Penenirmus jungens (Kellogg) from northern flicker, Penenirmus auritus (Scopoli) from the other four hosts, Picicola porisma Dalgleish from northern flicker, Picicola snodgrassi (Kellogg) from Picoides species, and Picicola marginatulus (Harrison) from pileated woodpeckers. Mean abundance of lice increased with the mean mass of their host. Neither the species richness of lice nor the prevalence of lice were related to host body mass. Host body mass explained 98% of the variation in mean intensity of louse infestation among hosts. The positive association of mean intensity and body size was also detected for three genera of lice. Louse intensity also increased with body size for individual birds, more so for some species of lice and hosts than others. Body size matters, but the adaptations that allow higher mean intensity on larger host species remain to be determined.

Functional visual sensitivity to ultraviolet wavelengths in the Pileated Woodpecker (Dryocopus pileatus), and its influence on foraging substrate selection

Most diurnal birds are presumed visually sensitive to near ultraviolet (UV) wavelengths, however, controlled behavioral studies investigating UV sensitivity remain few. Although woodpeckers are important as primary cavity excavators and nuisance animals, published work on their visual systems is limited. We developed a novel foraging-based behavioral assay designed to test UV sensitivity in the Pileated Woodpecker (Dryocopus pileatus). We acclimated 21 wild-caught woodpeckers to foraging for frozen mealworms within 1.2m sections of peeled cedar (Thuja spp.) poles. We then tested the functional significance of UV cues by placing frozen mealworms behind UV-reflective covers, UV-absorptive covers, or decayed red pine substrates within the same 1.2m poles in independent experiments. Behavioral responses were greater toward both UV-reflective and UV-absorptive substrates in three experiments. Study subjects therefore reliably differentiated and attended to two distinct UV conditions of a foraging substrate. Cue-naïve subjects showed a preference for UV-absorptive substrates, suggesting that woodpeckers may be pre-disposed to foraging from such substrates. Behavioral responses were greater toward decayed pine substrates (UV-reflective) than sound pine substrates suggesting that decayed pine can be a useful foraging cue. The finding that cue-naïve subjects selected UV-absorbing foraging substrates has implications for ecological interactions of woodpeckers with fungi. Woodpeckers transport fungal spores, and communication methods analogous to those of plant-pollinator mutualisms (i.e. UV-absorbing patterns) may have evolved to support woodpecker-fungus mutualisms.