Sphyrapicus Varius Research Articles

Population genomics of an emergent tri-species hybrid zone.

Isolating barriers that drive speciation are commonly studied in the context of two-species hybrid zones. There is, however, evidence that more complex introgressive relationships are common in nature. Here, we use field observations and genomic analysis, including the sequencing and assembly of a novel reference genome, to study an emergent hybrid zone involving two colliding hybrid zones of three woodpecker species: red-breasted, red-naped, and yellow-bellied sapsuckers (Sphyrapicus ruber, S.nuchalis, and S.varius). Surveys of the area surrounding Prince George, British Columbia, Canada, show that all three species are sympatric, and Genotyping-by-Sequencing identifies hybrids from each species pair and birds with ancestry from all three species. Observations of phenotypes and genotypes of mated pairs provide evidence for assortative mating, though there is some heterospecific pairing. Hybridization is more extensive in this tri-species hybrid zone than in two di-species hybrid zones. However, there is no evidence of a hybrid swarm and admixture is constrained to contact zones, so we classify this region as a tension zone and invoke selection against hybrids as a likely mechanism maintaining species boundaries. Analysis of sapsucker age classes does not show disadvantages in hybrid survival to adulthood, so we speculate the selection upholding the tension zone may involve hybrid fecundity. Gene flow among all sapsuckers in di-species hybrid zones suggests introgression probably occurred before the formation of this tri-species hybrid zone, and might result from bridge hybridization, vagrancies, or other three-species interactions.

Tree selection and foraging height of wintering Yellow-bellied Sapsuckers (Sphyrapicus varius) in an urban environment

ABSTRACT Yellow-bellied Sapsuckers (Sphyrapicus varius) drill sap holes in a variety of tree species to consume sap and bast. We examined the use of tree species in urban South Florida, a wintering ground for sapsuckers where their tree preferences have not previously been described. We determined that black olive (Bucida buceras) and tropical almond (Terminalia catappa) trees are strongly preferred and are used to a greater extent than all other trees. Coconut palms (Cocos nucifera) and baldcypress (Taxodium distichum) are also drilled but are less likely to become host trees with ≥100 bands of sap holes. In urban areas where black olive and tropical almond are grown, these trees are used so extensively by the sapsucker that bands of sap holes usually extend to within a meter of the ground surface. The urban setting of these trees potentially exposes them to predation by feral cats and puts them at risk of collisions with windows.

Early breeders choose differently - Refining measures of habitat quality for the yellow-bellied sapsucker (Sphyrapicus varius), a keystone species in the mixedwood boreal forest.

Despite the prevalent use of nest-site selection studies to define habitat quality for birds, many studies relying on use-availability analysis have found poor correlations between selected vegetation and reproductive success. Using 3 years of data from northeastern British Columbia (2007–2009), we determined timing of breeding from hatching dates and contrasted the nest-site selection of earlier (n = 22) with later-nesting pairs (n = 36) of yellow-bellied sapsuckers (Sphyrapicus varius), because early breeders were expected to be more reproductively successful. We then compared these choices with those identified from use-availability analysis, and determined whether reproductive performance (fledgling production) was related to selected vegetation. None of the vegetation characteristics selected for nest sites from available vegetation predicted reproductive performance. Earlier-nesting pairs fledged more young on average than later breeders (4.41, SE = 0.18 versus 3.92, SE = 0.16), and chose less decayed aspen trees for nesting, that were surrounded on average by 3 times the number of food trees (paper birch, Betula papyrifera). Potential preference for birch trees was masked in the use-availability analysis, because the selection rate was dominated by the choices of the larger number of later-nesting pairs. Similarly, the majority (69%) of nest cavity entrances faced south, but earlier breeding pairs excavated northward-oriented cavities more frequently than did later breeding pairs, which strongly predicted their higher fledgling production. To our knowledge, our study is the first to compare the choices of early versus later breeders to test the efficacy of use-availability studies in defining habitat quality. We found that use-availability analysis was inadequate for determining vegetation characteristics related to reproductive performance. In contrast, measuring the distinct preferences of earlier breeders resulted in an improved ability to measure habitat quality and explain the spatial distribution of yellow-bellied sapsuckers, a keystone species of the mixedwood boreal forest.

Population Genetics and Speciation of Yellow-Bellied, Red-Naped, and Red-Breasted Sapsuckers (Sphyrapicus varius, S. nuchalis, and S. ruber).

The root of understanding speciation lies in determining the forces which drive it. In many closely-related species, including Sphyrapicus varius, S. nuchalis, and S. ruber, it is assumed that speciation occurred due to isolation in multiple Pleistocene refugia. We used genetic data from 457 samples at the control region (CR), cytochrome oxidase I (COI), and chromo-helicase DNA binding protein (CHD1Z) to examine range-wide population genetic structure and differentiation amongst these 3 species across each species' breeding range. In addition, we modeled these species' ecological niches for the Holocene (~6000 years ago), Last Glacial Maximum (~22000 years ago), and Last Interglacial (~120000-140000 years ago) to determine if Pleistocene glaciations could have contributed to allopatric distributions, therefore allowing these groups to differentiate. Population genetic data show a potential Pleistocene refugium in Haida Gwaii, an east-west split among S. varius, and low genetic differentiation within each species. Our CR data show some polyphyly, while COI and CHD1Z data show differentiation among species using composite genotypes. Ecological Niche Modeling shows a large amount of niche overlap at each time period suggesting that S. varius, S. nuchalis, and S. ruber may not have been completely allopatric, and these species likely had repeated intermittent contact. Our data support the growing body of research that suggests differentiation despite gene flow.

Abundance and stability of populations of chewing lice (Phthiraptera: Amblycera and Ischnocera) infesting two species of woodpeckers (Aves: Piciformes: Picidae)

AbstractThe annual abundance of chewing lice (Phthiraptera) was recorded from 1996 to 2015 in Manitoba, Canada, on two species of woodpeckers (Piciformes: Picidae). Yellow-bellied sapsuckers (Sphyrapicus varius (Linnaeus)) were infested with Menacanthus pici (Denny) (Amblycera: Menoponidae) and Penenirmus auritus (Scopoli) (Ischnocera: Philopteridae); northern flickers (Colaptes auratus (Linnaeus)) were also infested with M. pici, as well as two other Ischnocera, Penenirmus jungens (Kellogg) and Picicola porisma Dalgleish. The mean annual abundance varied from nine to 51 lice per bird for the four species, with prevalence, mean intensity, sex ratio, and nymphs per female also varying among louse species. Menacanthus pici populations on both hosts were unstable: abundance rose over two decades because of increasing prevalence, whereas the abundance of the other three louse species fluctuated around a mean. Population variability was similar for the lice on both hosts, with the metric, PV, ranging from 0.41 to 0.51 on a 0–1 scale, once the effect of the trend in abundance for M. pici had been removed. Although the population dynamics for species of lice on these two woodpeckers were distinct, inter-specific differences in population stability were less pronounced than observed in the few other species of bird lice studied in this way.

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.

Yellow-bellied Sapsuckers (Sphyrapicus varius) alter sap well locations in response to experimentally induced tree damage

ABSTRACT Yellow-bellied Sapsuckers (Sphyrapicus varius) regularly use paper birch (Betula papyrifera) as a source of sap during the breeding season and may position their sap wells on the tree in order to maximize sap extraction. Sap flow can be affected by tree damage, and altering sap well locations in response to such damage could enhance sapsucker foraging efficiency. We sought to determine if sapsuckers selectively drilled sap wells on damaged (experimentally girdled) paper birch trees over non-damaged healthy trees and, if so, whether the locations of the drill sites varied in response to this damage. Sapsuckers drilled holes on a significantly larger proportion of girdled trees than control trees (healthy trees on adjacent plots), and the holes were lower on girdled trees in comparison with control trees. These differences occurred even though control and girdled trees were of similar size (diameter) and had similar numbers of sap wells per tree. Yellow-bellied Sapsuckers appear to alter their fora...

Strong reproductive isolation and narrow genomic tracts of differentiation among three woodpecker species in secondary contact.

Hybrid zones allow the measurement of gene flow across the genome, producing insight into the genomic architecture of speciation. Such analysis is particularly powerful when applied to multiple pairs of hybridizing species, as patterns of genomic differentiation can then be related to age of the hybridizing species, providing a view into the build-up of differentiation over time. We examined 33809 single nucleotide polymorphisms (SNPs) in three hybridizing woodpecker species: Red-breasted, Red-naped and Yellow-bellied sapsuckers (Sphyrapicus ruber, Sphyrapicus nuchalis and Sphyrapicus varius), two of which (ruber and nuchalis) are much more closely related than each is to the third (varius). To identify positions of SNPs on chromosomes, we developed a localization method based on comparative genomics. We found narrow clines, bimodal distributions of hybrid indices and genomic regions with decreased rates of introgression. These results suggest moderately strong reproductive isolation among species and selection against specific hybrid genotypes. We found 19 small regions of strong differentiation between species, partly shared among species pairs, but no large regions of differentiation. An association analysis revealed a single strong-effect candidate locus associated with plumage, possibly explaining mismatch among the three species in genomic relatedness and plumage similarity. Our comparative analysis of species pairs of different age and their hybrid zones showed that moderately strong reproductive isolation can occur with little genomic differentiation, but that reproductive isolation is incomplete even with much greater genomic differentiation, implying there are long periods of time when hybridization is possible if diverging populations are in geographic contact.

Seasonal population dynamics of chewing lice (Phthiraptera: Amblycera and Ischnocera) infesting three species of woodpeckers (Aves: Piciformes: Picidae) in Manitoba, Canada

AbstractThree species of woodpeckers (Piciformes: Picidae) in Manitoba, Canada, were examined for chewing lice (Phthiraptera): the resident downy woodpecker (Picoides pubescens(Linnaeus),n=55), and two migrants, yellow-bellied sapsucker (Sphyrapicus varius(Linnaeus),n=316) and northern flicker (Colaptes auratus(Linnaeus),n=225). Six species were collected:Menacanthus pici(Denny) (Amblycera: Menoponidae) from all hosts, and five species of Ischnocera (Philopteridae):Penenirmus auritus(Scopoli) from downy woodpeckers and sapsuckers,Picicola snodgrassi(Kellogg) andBrueelia straminea(Denny) from downy woodpeckers, andPenenirmus jungens(Kellogg) andPicicola porismaDalgleish from flickers. Adults and nymphs were present on downy woodpeckers all year, and on migrant sapsuckers and flickers from when they arrived until they left, suggesting lice reproduce continuously on their hosts. Prevalence and mean intensities of louse infestations generally decreased from their respective springtime levels to their lowest values during or at the end of the breeding season of their hosts, and then increased in various degrees during the fall. No seasonal pattern in louse sex ratios was observed except on northern flickers, where male to female ratios for two of three species were lowest during the breeding season. Resident and migrant hosts had similar seasonal patterns of infestation by lice.

Resident and cavity-nesting avian community is affected by amount but not age of white pine in central Ontario mature mixedwood forests

Forests with old-growth white pines have been severely reduced compared with historical levels. We examined resident and cavity-nesting bird species abundances in winter and the breeding season, because some of these species may prefer old-forest habitats for breeding. We counted birds over 10 years in four mixedwood types: old pine, mature pine, mature nonpine, and selection-harvested stands. We expected that old pine stands would be selected by some species because of abundant snags and large trees for foraging. We assessed habitat use among years and changes following harvesting. Counts of nomadic species varied across years but counts for others did not. Species used old and mature pine mixedwoods equally and more than nonpine or harvested stands in winter and for breeding, but old stands were not preferred. Important variables included percent pine and large tree density. Selection harvesting benefitted Yellow-bellied Sapsuckers but reduced counts of Black-capped Chickadees and Brown Creepers. Black-capped Chickadees changed habitats between seasons and in some years. Black-backed Woodpeckers were most common in pine stands but abundant in harvested stands for 2 years following cutting. Regardless of stand age, large (>40 cm) pines provide important habitat for residents and cavity nesters.

Chewing lice (Phthiraptera: Amblycera and Ischnocera) infesting woodpeckers and sapsuckers (Aves: Piciformes: Picidae) in Manitoba, Canada

AbstractFive species of woodpeckers (Piciformes: Picidae) in Manitoba, Canada were examined for chewing lice (Phthiraptera: Amblycera and Ischnocera): downy woodpecker (DOWO) (Picoides pubescens (Linnaeus), n=56), hairy woodpecker (HAWO) (Picoides villosus (Linnaeus), n=32), pileated woodpecker (PIWO) (Dryocopus pileatus (Linnaeus), n=12), northern flicker (NOFL) (Colaptes auratus (Linnaeus), n=223), and yellow-bellied sapsucker (YBSA) (Sphyrapicus varius (Linnaeus), n=192). Seven species of lice were collected (total number=40 613): Menacanthus pici (Denny) from all species of woodpeckers, Brueelia straminea (Denny) from both species of Picoides Lacépède, Penenirmus jungens (Kellogg) from northern flicker, Penenirmus auritus (Scopoli) from all species of woodpeckers examined except northern flickers, Picicola porisma Dalgleish from northern flickers, Picicola snodgrassi (Kellogg) from both species of Picoides, and Picicola marginatulus (Harrison) from pileated woodpeckers. Prevalence for total louse infestation ranged from 32.3% to 85.7% (NOFL>YBSA>PIWO>DOWO>HAWO). Mean intensity for total lice ranged from 29.2 to 232.4 (PIWO>NOFL>HAWO>YBSA>DOWO). Infestation parameters for each louse/host combination are provided. Distribution of louse infestations was highly aggregated. In all louse/host combinations, either females were more prevalent than males or there was no significant deviation from 50:50. There was a tendency for louse species to co-occur on the same host specimen.

How important is dead wood for woodpeckers foraging in eastern North American boreal forests?

Dead and decaying trees may be a limited resource for woodpeckers in managed forests, especially for species that rely on dead wood for nesting and foraging. Whereas recent nest web studies greatly increased our understanding of nest tree use by woodpeckers, knowledge on woodpeckers foraging requirements is much less developed. We quantified and compared tree selection patterns and foraging behavior of six bark-foraging woodpeckers – downy woodpecker (Picoides pubescens), hairy woodpecker (Picoides villosus), American three-toed woodpecker (Picoides dorsalis), black-backed woodpecker (Picoides arcticus), yellow-bellied sapsucker (Sphyropicus varius) and pileated woodpecker (Dryocopus pileatus) – that co-occur in eastern boreal forests of North America. A total of 271 observation bouts and more than 600 foraging trees were recorded at three study sites characterized as mixedwood, conifer, and burn. Our results show that dead wood represents an important foraging substrate for most bark-foraging woodpeckers in Canadian eastern boreal forests. However, significant differences in individual species were found with regard to substrate use patterns, foraging behavior and associated prey. Woodpeckers were categorized according to their selection for specific stages of tree degradation, with the yellow-bellied sapsucker and the pileated woodpecker representing opposite ends of this gradient. The black-backed woodpecker showed the highest use of dead wood and was very specific in its tree selection by using mostly recently dead trees. We emphasize that providing foraging substrates for most woodpecker species not only requires maintaining dead wood but also paying heed to the underlying dynamics of dead wood (e.g. recruitment and degradation) in managed boreal forest landscapes.

Benefits of aggregate green tree retention to boreal forest birds

We evaluated the function of aggregate tree retention as mature habitat in a harvested matrix for boreal forest birds in a boreal mixedwood. We compared insular and peninsular residual patches ranging from 0.51ha to 4.32ha with plots in dispersed retention and intact forest to evaluate their usefulness to forest birds as habitat in a harvested matrix. We found that forest bird communities were significantly different in all three treatments and that bird communities in patches were an intermediate condition between intact forest and dispersed retention harvest. We observed 12 predominantly forest species, including Brown Creeper (Certhia americana), Ovenbird (Seiurus aurocapilla), Yellow-bellied Sapsucker (Sphyrapicus varius), and Black-throated Blue Warbler (Setophaga caerulescens), in patches at abundance levels between dispersed retention and intact forest plots. For these species, it appears that patches offer an important habitat in a harvested matrix but at lower abundance than in intact forest. Of the 12 predominantly forest species found in patches, 8 had confirmed breeding. Our results suggest that aggregate retention patches provide breeding quality habitat to a large group of forest species; however, the patches are not equivalent to intact forest suggesting that intact forest should be maintained in landscapes.

The effects of Forest Stand Improvement Practices on occupancy and abundance of breeding songbirds

Silviculture can play an important role in managing avian habitat. In 2010 the Vermont Natural Resource Conservation Service, in conjunction with Audubon Vermont, implemented a Forest Stand Improvement initiative designed to improve timber quality while increasing habitat diversity for forest breeding songbirds. To evaluate the effectiveness of this program in improving avian habitat, we conducted point count surveys of breeding birds in harvested and control sites in 2012 and 2013, 1–3years post-harvest. Harvesting resulted in mean decreases of 18% in basal area, 10% in canopy cover, and 10% in canopy tree density while piles of woody debris per ha increased by 402%. Occupancy and abundance estimates for 24 and 18 bird species respectively were derived using Program MARK. Compared to controls, occupancy rates of four songbird species were greater on harvested sites – rose-breasted grosbeak (Pheucticus ludovicianus), yellow-bellied sapsucker (Sphyrapicus varius), chestnut-sided warbler (Setophaga pensylvanica), and mourning warbler (Geothlypis philadelphia)—while occupancy of one species—black-and-white warbler (S. fusca)—was significantly lower. Two species were significantly more abundant at harvested sites—rose-breasted grosbeak and yellow-bellied sapsucker—while two species were less abundant—hermit thrush (Catharus guttatus) and black-and-white warbler. Piles of woody debris left after harvests were negatively associated with site occupancy for 3 out of 10 understory species. Overall, our results suggest that this program retains all interior forest species and has a slight positive impact on gap and early successional species abundance and occupancy in the first 1–3years post-harvest. This study provides the first quantitative examination of the impact that Vermont NRCS’s Forest Stand Improvement program has had on forest breeding birds.

Effect of selection logging on Yellow-bellied Sapsucker sap-feeding habits in Algonquin Provincial Park, Ontario

The sap-feeding behaviour of a keystone woodpecker species, the Yellow-bellied Sapsucker (Sphyrapicus varius (Linnaeus, 1766)), was compared between high-quality uncut stands and stands harvested with various forms of selection logging in the hardwood forests of Algonquin Provincial Park, Ontario. We examined (i) the average distances that sapsuckers travelled from their nest tree to sapwell trees, (ii) the characteristics of active sapwell trees compared with overall stand characteristics, and (iii) the reuse of sapwell trees after 1 or 2 years. We found that sapsuckers travelled approximately the same average distance from their nests to sapwell trees, regardless of logging treatment. The characteristics of sapwell trees were overall unaffected by logging: unhealthy trees, sugar maple (Acer saccharum Marshall), and yellow birch (Betula alleghaniensis Britton) were used at similar proportions to their stand-level availability in reference and harvested stands. Trees with old sapwells and large-diameter trees were used significantly more than their stand-level availability; thus the retention of these trees during tree-marking procedures may preserve sap foraging habitat. The reuse of sapwell trees did not vary between treatments, and on average, over half of the sapwell trees showed evidence of reuse the following year.

Fossil woodpeckers from Bermuda with the description of a new species ofColaptes(Aves: Picidae)

Abstract Fossils of woodpeckers (Picidae) occur on Bermuda in late Pleistocene and Holocene deposits. Most of these are from a flicker (Colaptes), presumably derived from the North American Colaptes auratus that was smaller than all mainland forms of that species. The Bermuda flicker was larger than C. a. gundlachi of Grand Cayman and is named as a new species Colaptes oceanicus, that probably persisted into the colonial period (1600s). Three fossils are referred to the migratory Yellow-bellied Sapsucker (Sphyrapicus varius), which winters in small numbers on Bermuda. One distal end of a tarsometatarsus of a woodpecker appears to differ from either of the previous species, but its identity was not further determined. Colaptes oceanicus would probably have excavated nest holes in the resident palm trees (Sabal bermudana) and in rotten limbs and stumps of hardwoods. These excavations would have been crucial for the evolution of the small owl Aegolius gradyi and probably provided shelter for other Bermuda or...

Nest-site selection by old boreal forest cavity excavators as a basis for structural retention guidelines in spatially-aggregated harvests

Cavity excavators (woodpeckers, chickadees, nuthatches) are vulnerable to loss of old forest associated with traditional harvest practices. In the boreal plains of Canada, old forest excavators are retained in the short term in small (<100ha) and large (1000sha) harvests with residual trees and patches. Information on habitat selection can be used to guide “what, where, and how much” structure to retain and ensure excavators, and the secondary species that use their cavities, are conserved in harvests in the short term. We examined multi-scale nest-site use and selection by excavators in intact old upland forest and spatially-aggregated harvests with structural retention and developed guidelines for the types and spatial arrangement of trees, patches, and stands retained during forest planning (i.e. planned residuals) and harvesting (i.e. operator residuals). In both intact and harvest landscapes, live large (>35cm) and tall (>25m) trembling aspen (Populus tremuloides) with multiple (∼20) conks of a heartrot fungus (Phellinus tremulae) were the preferred cavity trees for yellow-bellied sapsucker (Sphyrapicus varius), hairy woodpecker (Picoides villosus), and pileated woodpecker (Dryocopus pileatus). Short (∼10m), broken-top aspen snags of medium (>20cm) and large (>35cm) diameter were preferred by black-capped chickadees (Poecile atricapillus) and northern flickers (Colaptes auratus), respectively. In the harvests, sapsuckers, hairy woodpeckers, and flickers selected cavity trees in clumps with other medium- and large-diameter aspen with conks. Black-capped chickadees selected trees with no live large conifers within ∼10m. Sapsuckers selected old aspen and mixedwood stands in intact landscapes. In harvest landscapes, sapsuckers selected trees in or near planned patches greater than 5ha and composed of mature and old aspen and mixedwood stands. Sapsuckers tended to nest in areas with ∼50% residual forest cover whereas flickers selected open areas of cutblocks away from planned patches. We recommend harvest operators retain several live, large (>35cmdbh) aspen with numerous (∼20) fungal conks in clumps that are adjacent to or near (<60m) large (>5ha) patches. Planned patches should have one to two thirds of their area derived from mature and old aspen and mixedwood stands and should be at least 5ha, with most greater than 15ha. These prescriptions will facilitate retention of the cavity-using assemblage of old upland forest in aggregated harvests in the short term. However, regional strategies for old forest conservation may be necessary to conserve cavity users in managed forest landscapes over the long term.

Managing ecological traps: Logging and sapsucker nest predation by bears

AbstractWe tested the equal preference ecological trap hypothesis for breeding yellow‐bellied sapsuckers (Sphyrapicus varius) along a time‐since‐harvest gradient (1–5 yr, 16–20 yr, 21–25 yr, and &gt;60 yr) in selection system‐logged hardwood forests in Algonquin Provincial Park, Ontario. Yellow‐bellied sapsuckers preferred 1–5 year and &gt;60‐year‐old cuts equally and more than 16–20 year and 21–25‐year‐old cuts. More‐abundant arthropod food and/or higher‐quality sap resources may have attracted yellow‐bellied sapsuckers to 1–5 year and &gt;60‐year‐old cuts. Only 52% of pairs raised fledglings in 1‐ to 5‐year‐old cuts during years when nest predation by American black bears (Ursus americanus) was common, the incidence of which was negatively related to increased availability of American beech (Fagus grandifolia) nuts from the previous autumn. By contrast, 88% of pairs raised fledglings in all years in &gt;60‐year‐old cuts. One‐ to 5‐year‐old cuts were demographic sinks that represent equal‐preference ecological traps in years when nest predation by bears was common, whereas &gt;60‐year‐old cuts were always demographic sources. High‐quality habitat cues for nesting yellow‐bellied sapsuckers appear to be retained for 1–5 years after selection system logging but fail to deliver safe nest sites. Cavities excavated in heart‐rot‐infected nest trees are least likely to be depredated because cavity walls are typically harder and deter entry by depredating bears. Retaining more potential nest trees per ha at harvest (especially American beech with heart‐rot) may increase the proportion of sapsucker nests that are excavated in bear‐resistant trees, thereby reducing nest predation and increasing fecundity. © 2012 The Wildlife Society.

Habitat Use of Woodpeckers in the Big Woods of Eastern Arkansas

AbstractThe Big Woods of eastern Arkansas contain some of the highest densities of woodpeckers recorded within bottomland hardwood forests of the southeastern United States. A better understanding of habitat use patterns by these woodpeckers is a priority for conservationists seeking to maintain these high densities in the Big Woods and the Lower Mississippi Alluvial Valley as a whole. Hence, we used linear mixed-effects and linear models to estimate the importance of habitat characteristics to woodpecker density in the Big Woods during the breeding seasons of 2006 and 2007 and the winter of 2007. Northern flicker Colaptes auratus density was negatively related to tree density both for moderate (&amp;gt;25 cm diameter at breast height) and larger trees (&amp;gt;61 cm diameter at breast height). Red-headed woodpeckers Melanerpes erythrocephalus also had a negative relationship with density of large (&amp;gt;61 cm diameter at breast height) trees. Bark disfiguration (an index of tree health) was negatively related to red-bellied woodpecker Melanerpes carolinus and yellow-bellied sapsucker Sphyrapicus varius densities. No measured habitat variables explained pileated woodpecker Dryocopus pileatus density. Overall, the high densities of woodpeckers observed in our study suggest that the current forest management of the Big Woods of Arkansas is meeting the nesting, roosting, and foraging requirements for these birds.

Reproductive success of cavity-nesting birds in partially harvested woodlots

Cavity-nesting birds are dependent on large declining and dead trees that are frequently removed during partial harvesting. We compared breeding densities, nest survival, nest site characteristics, food abundance, and reproductive parameters of six species of cavity-nesting birds in partially harvested and reference woodlots in southwestern Ontario, Canada. Silvicultural practices significantly altered woodlot structure, with treatment-specific effects on bark arthropod biomass, fledging dates for the Red-bellied Woodpecker ( Melanerpes carolinus (Linnaeus, 1758)), and site suitability for the Yellow-bellied Sapsucker ( Sphyrapicus varius (Linnaeus, 1766)). Red-bellied Woodpecker, Downy Woodpecker ( Picoides pubescens (Linnaeus, 1766)), and Hairy Woodpecker ( Picoides villosus (Linnaeus, 1766)) experienced lower breeding densities in recently cut sites. Daily survival rates were generally greater for nests positioned higher up in large trees and for Northern Flicker ( Colaptes auratus (Linnaeus, 1758)) nests excavated in healthy and hard wood. Conversely, the Black-capped Chickadee ( Poecile atricapillus (Linnaeus, 1766)) had higher daily survival rates in low, small trees (&lt;10 cm diameter at breast height) and sites with lower arthropod abundance. We conclude that although partial harvesting has the potential to decrease cavity-nesting bird breeding densities, conscientious cavity tree retention during harvest may provide suitable nesting sites that maintain high rates of nest success, regardless of the silvicultural treatments that we examined. However, further research is required to monitor these trends beyond a single harvesting rotation.