Colaptes Auratus Research Articles

Choice of foraging habitat by northern flickers reflects changes in availability of their ant prey linked to ambient temperature

Foraging theory suggests animals should prefer habitats with a greater density of prey, but few have investigated whether birds change foraging habitats according to short-term changes in prey abundance caused by weather. We studied a woodpecker, the northern flicker (Colaptes auratus), in which the diet is composed mainly of ants collected on the ground surface. We measured the surface density of the ant prey in 1-m2 quadrats placed in 2 habitat types that had different thermal properties: open grassland and forest. The density of ants varied according to year of the study, habitat type, date during the summer, and time of day and was strongly associated with ambient temperature. In the shaded forest habitat, ant density increased linearly with air temperatures between 6 and 28 °C. In contrast, the surface activity of ants in the open habitat exposed to sun began to decline once ground surface temperatures reached 26 °C. Ant densities were higher in the open habitat than in the shade in relatively cold conditions but were higher in the shaded forest habitat when it was hot. Using radio telemetry, we recorded the habitat use of foraging flickers and found they shifted from foraging in the open when it was cold to foraging in shaded habitats when it was hot. Flickers tracked the density of their main prey on fine spatial and short temporal scales consistent with foraging theory.

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...

Brood age and size influence sex-specific parental provisioning patterns in a sex-role reversed species

Parents of altricial young alter provisioning effort based on offspring demand, but life-history differ- ences between the sexes can influence the willingness of each parent to invest in a brood. Previous studies on sex- specific provisioning roles in altricial species suggest a wide range of responses by males and females, which vary depending on the life history of the species. The Northern Flicker (Colaptes auratus) is unusual among altricial birds, as it has partly reversed sex roles with males investing more in parental care than females, it has no-extra-pair young, and it engages in facultative polyandry. We inves- tigated sex-specific provisioning patterns to see what fac- tors (brood size, nestling age, adult age, body condition, nestling sex ratio and partner provisioning level) affected provisioning rates. Additionally, we determined nestling growth rates and estimated nestling energetic demands. Based on 232 filmed provisioning bouts at 82 nests, we found that males provisioned 1.11 times more than females. In addition, provisioning rates by males were primarily associated with nestling age, female provision- ing, brood size, and body condition. Provisioning by females was more strongly related to the male's provi- sioning effort and brood size. Per capita provisioning rates decreased with brood size, resulting in lighter nestlings in large broods. Our results suggest that both parents responded to the changes in brood demands, but do so governed by different factors. We suggest that the rela- tively high provisioning by males is related to high male assurance of paternity.

Parents take both size and conspicuousness into account when feeding nestlings in dark cavity nests

Parent birds respond to a variety of cues from their offspring when provisioning them with food. Bright flange colours and large body size are two traits of offspring that many parents seem to favour, but little is known about how such traits interact. By experimentally altering the difference in mass between nestmates while concurrently blackening the flanges of either the large or small nestlings in the brood, we tested whether large body size could compensate for dull coloration. In three species of cavity nesters (northern flicker, Colaptes auratus, great tit, Parus major, and pied flycatcher, Ficedula hypoleuca), doubly disadvantaged offspring that were both small and dull performed the worst, whereas large and bright offspring received the most provisioning, consistent with the idea of additive effects. We used regression to show that, for flickers, dull (blackened) nestlings performed as well as bright nestlings when they were 20% larger than their bright nestmates. For passerines, dull nestlings had to be 30–40% larger than bright nestlings to receive equivalent amounts of food from parents. Within-brood differences in mass before manipulation were often greater than this size difference threshold, suggesting that hatching asynchrony has a stronger influence on food allocation than do colour differences among siblings.

Nest-Site Characteristics of Three Woodpecker Species in Managed Ponderosa Pine Forests of the Eastern Cascade Range

Abstract In order to conserve populations of woodpeckers in managed forests of the inland Northwest, managers require information about the nest substrates (for example, trees and snags) in which woodpeckers excavate cavities and the habitat characteristics surrounding those substrates. I describe and compare the nest-site characteristics of the White-headed Woodpecker (Picoides albolarvatus), Hairy Woodpecker (Picodes villosus), and Northern Flicker (Colaptes auratus) in burned and unburned logged Ponderosa Pine (Pinus ponderosa) stands of the eastern Cascade Range of Washington, 2003 to 2010. All 3 woodpecker species most frequently excavated cavities in well-decayed snags. In burned stands, Northern Flickers used nest substrates that had a larger mean diameter at breast height (dbh) than those used by Hairy Woodpeckers, and that were shorter in height than those used by Hairy and White-headed Woodpeckers. Northern Flickers also excavated cavities lower in height than Hairy Woodpecker cavities. In unbur...

Survival analysis of a critical resource for cavity‐nesting communities: patterns of tree cavity longevity

Tree cavities are a vital multi-annual resource used by cavity-nesting birds and mammals for nesting and shelter. The abundance of this resource will be influenced by the rates at which cavities are created and destroyed. We applied the demographic concepts of survival and longevity to populations of tree holes to investigate rates of loss for cavities in three tree species, as well as how characteristics of nest trees, habitat type, and species of excavator affected the persistence of tree cavities in trembling aspen, Populus tremuloides (95% of cavities were in aspen trees), in interior British Columbia, Canada. By modeling survival of 1635 nesting cavities in aspen over a time span of 16 years, we found that the decay stage of the nest tree was the most important factor determining cavity longevity. Cavities in trees with advanced decay had a relatively short median longevity of 7 years (95% CI 6-9 years), whereas those in living trees had a median longevity of more than 15 years. We found that cavity longevity was greater in continuous forest than in aspen grove habitat. Interestingly, cavities formed by weak excavators survived as long as those created by Northern Flickers (Colaptes auratus), despite occurring in more decayed tree stems. Thus, weak excavators may be selecting for characteristics that make a tree persistent, such as a broken top. Our results indicate that retention of cavities in large, live aspen trees is necessary to conserve persistent cavities, and that cavity longevity will have a large effect on the structure and function of cavity-using vertebrate communities.

Experimental effects of structural enrichment on avian nest survival

Managers of landscapes dedicated to commodity production require information about how alternative practices can promote retention of native biological diversity. Retaining or creating structural features (e.g., snags or downed logs) needed to fulfill life history requirements may benefit populations and communities. However, demographic responses of species to alternative practices have received little research attention. We tested nest survival of cavity-dependent birds in response to experimental structural enrichment by creating snags on 28 plots, Oregon, USA, 2008–2010. Each plot represented one of six combinations of created snag density (0.5, 1, and 2snags/ha) and spatial dispersion (clumps of 5–7 snags or dispersed individual snags). We monitored 506 nests built by 10 species; three species nested in sufficient numbers for analysis. Chestnut-backed chickadee Poecile rufescens nest success was highest in the medium density clumped created snag treatment (average proportion of successful nests=0.76; 95% CI=0.61–0.87) and lowest in the low density clumped treatment (average proportion of successful nests=0.39; 95% CI=0.20–0.62). We did not find a response of either house wren Troglodytes aedon or northern flicker Colaptes auratus nest success to the experimental treatments. Period survival rates were 0.57 (95% CL: 0.39–0.72) for CBCH; 0.71 (95% CL: 0.51–0.84) for HOWR; and 0.59 (95% CL: 0.34–0.77) for NOFL. Our study suggests that creating snags in commercial harvest units is an effective practice for increasing structural complexity and supporting nesting communities of cavity-dependent birds. While leaving either clumped or dispersed created snags at a density of ∼1ha should support nest survival rates that are similar to those reported from unmanaged forests, we emphasize that this type of structural enrichment is not a panacea for species that require very large snags or snags that occur under complex forest canopies. Retention of existing structural features in reserve areas may be an appropriate practice for conserving species with nesting requirements that differ from those we evaluated in our study.

An Unusually Synchronous Double Brooding Attempt by a Northern Flicker Pair

We report an unusual case of a monogamous pair of Northern Flickers (Colaptes auratus) initiating a second clutch while there were still nestlings in the first nest. The male and female incubated at both nests but only the male fed nestlings at the first nest. The second nest attempt was abandoned after the first nestlings fledged, possibly because the two broods were too synchronous in timing for the male to contribute sufficiently to both. Double-brooding has not been previously documented for Northern Flickers.

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.

Woodpecker Nest Survival in Burned and Unburned Managed Ponderosa Pine Forests of the Northwestern United States

Abstract. Woodpeckers are particularly susceptible to habitat changes resulting from forest management because of their reliance on trees and snags for nesting and foraging. However, the influence of habitat variables on the reproductive success of woodpeckers has received less attention than it has in other avian taxonomic groups. We estimated nest-survival rates for the White-headed Woodpecker (Picoides albolarvatus), Hairy Woodpecker (P. villosus), and Northern Flicker (Colaptes auratus) in managed ponderosa pine (Pinus ponderosa) forests along the eastern slope of the Cascade Range in Washington, 2005–2010. Using a model-selection framework, we found that the most supported models included terms for a quadratic effect of date and habitat type for the Hairy Woodpecker, a negative effect of percent shrub cover for the White-headed Woodpecker, and a negative linear effect of date and habitat type, a negative linear effect of snag density, and a positive linear effect of tree density for the flicker. Surv...

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.

Modeling nest survival of cavity‐nesting birds in relation to postfire salvage logging

AbstractSalvage logging practices in recently burned forests often have direct effects on species associated with dead trees, particularly cavity‐nesting birds. As such, evaluation of postfire management practices on nest survival rates of cavity nesters is necessary for determining conservation strategies. We monitored 1,797 nests of 6 cavity‐nesting bird species: Lewis's woodpecker (Melanerpes lewis), hairy woodpecker (Picoides villosus), black‐backed woodpecker (P. arcticus), northern flicker (Colaptes auratus), western bluebird (Sialia mexicana), and mountain bluebird (S. currucoides) from 1994 to 2004 in ponderosa pine (Pinus ponderosa), mixed‐severity burned forests (partially logged and unlogged) of Idaho, USA. Based on a priori hypotheses, we modeled daily survival rate (DSR) of nests as a function of abiotic (temperature, precipitation), temporal (time since fire, calendar year) and biotic factors (distance to unburned forest, nest height, and tree harvest [partial‐salvage logging vs. unlogged]). Multiple abiotic and biotic factors, other than direct effects of salvage logging, affected daily survival rates of breeding cavity‐nesting birds. Hairy woodpecker was the only species in which partial‐salvage logging had a measurable, negative impact on DSR. Managers implementing carefully planned salvage logging prescriptions that include both unlogged reserves and partially logged areas can expect to maintain habitat for successfully breeding cavity‐nesting birds of the interior northwestern United States. Our results also suggest that nest survival for some species of cavity‐nesting birds could be improved if unlogged reserves are located centrally in postfire forests, distant from unburned habitats that potentially serve as sources of nest predators. © 2011 The Wildlife Society.

Effects of Gypsy Moth Outbreaks on North American Woodpeckers

We examined the effects of the introduced gypsy moth (Lymantria dispar) on seven species of North American woodpeckers by matching spatially explicit data on gypsy moth outbreaks with data on breeding and wintering populations. In general, we detected modest effects during outbreaks: during the breeding season one species, the Red-headed Woodpecker (Melanerpes erythrocephalus), increased over pre-outbreak levels, while during the winter one species, the Yellow-bellied Sapsucker (Sphyrapicus varius), increased and one, the Downy Woodpecker (Picoides pubescens), decreased from pre-outbreak levels. Responses following outbreaks were similarly variable, and in general we were unsuccessful at predicting population responses to outbreaks from a priori knowledge of woodpecker ecology and behavior. We did, however, find evidence that the response of at least half of the species changed over the 34-year period covered by the study: except for the Northern Flicker (Colaptes auratus), whose response to outbreaks during the winter decreased, populations generally responded more positively to outbreaks with time. This temporal response suggests that North American woodpeckers may be taking greater advantage of the resource pulse and/or habitat changes caused by outbreaks of this exotic pest now than previously, so in the future the effects of gypsy moth outbreaks on these species may increase.

Do aggregated harvests with structural retention conserve the cavity web of old upland forest in the boreal plains?

Boreal species that are dependent on old forests, such as many cavity-using birds and mammals, are at high risk from conventional harvest practices. These species may benefit from ecologically sustainable forest management practices that increase heterogeneity within stands and across landscapes. Structural retention within cutblocks and spatial aggregation of cutblocks into large (1000s ha) harvest units are two such management practices being implemented by forestry companies in the boreal plains of Alberta and Saskatchewan. However, little is known about the implications of these practices for old forest species. The goal of our study was to determine if the cavity-using assemblage associated with old upland forest in this region is retained within aggregated harvests with structural retention. We used a cavity web approach to describe and contrast interactions among cavity excavators (woodpeckers, chickadees, and nuthatches) and the secondary (i.e. non-excavating) species reusing their cavities. We described the cavity web for two intact landscapes of old upland forest and for two aggregated harvest landscapes. We identified four key excavators of intact forest: yellow-bellied sapsucker (Sphyrapicus varius), hairy woodpecker (Picoides villosus), northern flicker (Colaptes auratus), and pileated woodpecker (Dryocopus pileatus). These woodpeckers should be considered key excavators primarily of mature and old aspen forest, which dominated the study landscapes. Each woodpecker filled a unique role in the cavity web and all are important for conservation of two mammal and three bird species that used their cavities. In the short term (i.e. within four years post-harvest), the key cavity excavators and many secondary cavity-using species associated with intact forest were retained in the harvested landscapes. One secondary species (American kestrel (Falco sparverius)) was unique in the harvest cavity web. Compared to the intact cavity web, the harvest web had lower abundance of sapsuckers, greater abundance of flickers, and high reuse of flicker cavities by kestrels. These differences were associated with the shift from intact forest to a landscape characterized by patches of old forest surrounded by early-successional habitat. Abundances of hairy and pileated woodpeckers were too low to detect differences between intact and harvested landscapes. The key excavators primarily used trembling aspen (Populus tremuloides) for cavity trees and thus aspen should be targeted for retention in harvested landscapes. A more detailed examination of the habitat requirements of the key excavators is needed to develop best practices for tree and patch retention and ensure conservation of the cavity-using assemblage in aggregated harvests.

Woodpeckers increase in abundance but maintain fecundity in response to an outbreak of mountain pine bark beetles

Many temperate woodpecker species are thought to be highly conservative in their fecundity with little response to fluctuations in availability of resources. In a 15-year field study in interior British Columbia, we evaluated responses in abundance and fecundity of six species of resident and migrant woodpeckers (downy woodpecker [ Picoides pubescens], hairy woodpecker [ Picoides villosus], American three-toed woodpecker [ Picoides dorsalis], pileated woodpecker [ Drycopus pileatus], northern flicker [ Colaptes auratus], and red-naped sapsucker [ Sphyrapicus nuchalis]) to a large-scale outbreak of mountain pine bark beetles that resulted in a strong positive pulse in food supply. Population densities of woodpecker species increased during outbreak years. Despite the year-round multi-annual increase in food resources, and in contrast to the strong increases in fecundity shown by nuthatches and chickadees, annual fecundity (as indicated by clutch size and number of nestlings that fledged) did not change for any woodpecker species over the study. Similarly, we found no changes in fecundity in response to selective forest harvesting despite numerical increases for woodpeckers at these sites. Our study confirms that these woodpecker species are conservative in their reproductive investment patterns even during strong multi-annual increases in food. Our findings indicate woodpecker populations are regulated numerically through variable survival and/or greater immigration rates, which can result in higher breeding densities temporarily during resource pulses.

Influence of Spring Temperatures and Individual Traits on Reproductive Timing and Success in a Migratory Woodpecker

ABSTRACT. We investigated the effect of spring temperatures, female age, and female body condition on the timing of laying in a migratory woodpecker, the Northern Flicker (Colaptes auratus), and looked at the relationship between laying date and reproductive success. Average annual laying dates in the population, recorded over 12 years, were not related to the North Atlantic Oscillation or the Pacific-North American climate indices but were earlier when average daily temperatures along the migration route of Northern Flickers along the Pacific coast of North America were warmer. However, the strongest negative correlation between laying dates and ambient temperatures occurred after the arrival of most birds on the breeding site, which suggests that the ability of females to accumulate resources for egg laying on the breeding site was an important determinant of laying times. At the population level, egg laying advanced by 1.15 days for every degree warmer on the breeding grounds. At the level of individua...

Mitochondrial DNA based phylogeny of the woodpecker genera Colaptes and Piculus, and implications for the history of woodpecker diversification in South America

The woodpecker genus Colaptes (flickers) has its highest diversity in South America and the closely related genus Piculus is restricted to South and Central America. Two species of flickers occur in North America, and one species is endemic to Cuba. We conducted a Bayesian phylogenetic analysis of three mitochondrial encoded genes (cyt b, COI, 12S rRNA) and confirmed that the two genera are paraphyletic. Three species historically classified as Piculus are actually flickers. We found that the Cuban endemic C. fernandinae is the most basal species within the flickers and that the Northern Flicker is the next most basal species within the Colaptes lineage. The South American clade is most derived. The age of the South American diversification is estimated to be 3.6MY, which is synchronous with the emergence of the Isthmus of Panama. The pattern of diversification of South American flickers is common among South American woodpeckers. Although woodpeckers have their greatest diversity in South America, we hypothesize that woodpeckers (Family Picidae) originated in Eurasia, dispersed to North America via the Bering land bridge, and multiple lineages entered South America as the Isthmus approached its final closing.

Evaluating Color and Fading of Red-Shafted Flicker (Colaptes auratus cafer) Feathers: Technical and Cultural Considerations

Fading behavior of undyed feathers has not received much attention in conservation literature and as a result feathers are categorized with other natural materials as being fugitive to display lighting, based on anecdotal evidence. The authors investigated Red-shafted Flicker feathers, which have carotenoid-based colorant systems and significance in North American native regalia, to demonstrate how lighting guidelines could be informed by a multivariate approach that considers material sensitivity, properties of value, and use before entering a museum collection. Ornithological literature reviewed demonstrates that feathers are highly differentiated in their sources of coloration, which include chemistry, structure, diet, age and gender, all resulting in varying responses to illumination. The authors explore the value placed on color by original fabricators, and how use and attitudes toward color contribute to the collections for which we assume stewardship. Red-shafted Flicker feathers were exposed to equivalent photometric doses in order to compare results from window-fading and microfading to Blue Wool Standards. Results indicate color changes more stable than Blue Wool 1 and 2, with ultraviolet radiation playing a significant role in fading. Microfading is beneficial for measuring color change because the variability within and between feathers is eliminated as the sample site remains unvaried.

Spatial Dependence in Northern Flicker Habitat–Reproduction Relationships: An Application of Dutilleul's Modifiedt-test

Abstract. While there is growing awareness in ecology of spatial dependency, the application in avian ecology of spatially explicit statistical methods is rare in areas such as habitat—reproduction relationships. We compared nonspatial vs. spatially explicit tests of correlation between a measure of reproduction and a habitat attribute associated with Northern Flicker (Colaptes auratus) nests. While nonspatial tests showed a significant positive correlation between nest productivity and canopy cover of conifers, Dutilleul's modified t-test, which reduces the effective sample size by accounting for dependence among sampled nest trees, showed no significant correlation. These results may be due to spatial autocorrelation of both canopy cover of conifers and nest productivity at the scale of <1 km. Low localized nest productivity appears to have been driven by nest predation rather than by conifer cover. Our results illustrate the utility of this simple modification for examining ecological correlations in t...