Bewick's Wren Research Articles

Avifauna Assemblages in Sand Shinnery Oak Shrublands Managed with Prescribed Fire

Sand shinnery oak (Quercus havardii) shrublands are estimated to have once occupied 5−7 million ha across the southwestern United States. As a result of herbicide and plowing, this endemic vegetation community has been significantly reduced in extent. Further, sand shinnery oak shrublands were historically maintained by relatively frequent fires, but recent fire suppression has resulted in substantial changes in plant community composition and structure where this vegetation type remains. Few studies have been conducted to determine wildlife species composition and richness in remaining sand shinnery oak shrublands and how management practices, such as fire, may influence species occurrence. In this study, we conducted breeding bird surveys in an intact sand shinnery oak shrubland managed with prescribed fire in western Oklahoma to describe the breeding bird assemblage and evaluate the effects of prescribed fire on species abundance. We found the breeding bird community varied along a gradient of sites with high tree/tall shrub density to more open sites dominated by grasses and sand shinnery oak. Bird species richness increased with higher tree/tall shrub densities and declined with greater cover of grasses, shrubs, and bare ground. The 10 most common bird species displayed a range of responses to prescribed fire. Species such as northern bobwhite (Colinus virginianus) and field sparrow (Spizella pusilla) had their greatest relative abundance in recently burned patches, and species such as painted bunting (Passerina ciris) and Bewick's wren (Thryomanes bewickii) were most abundant in patches that were > 36 mo post fire, with many of the remaining species having peak abundance in intermediate times since fire. Our findings show prescribed fire can be used to create a diversity of vegetation structure that provides habitat for multiple shrubland and grassland bird species. However, factors such as tree density and precipitation may influence the response of bird species to prescribed fire.

Effects of Class-Level Vegetation Characteristics on Nesting Success of Bewick's Wrens

Understanding how habitat affects avian nest success is paramount, particularly when nest boxes are used. Once widespread, Thryomanes bewickii (Bewick's Wren) are presently confined to south-central and western North America. Our objective was to determine which vegetation variables influenced Bewick's Wren nesting success in nest boxes in central Texas. Between 2013 and 2014, we estimated nest success for 83 nests and measured vegetation variables surrounding nest boxes. Shrubland perimeter-area ratio negatively impacted nest success, whereas distance to nearest tree had a positive effect. Our results indicate that nests close to trees and in patches with large areas exposed to edge experienced lower nest success; these vegetation variables should be considered when using nest boxes to manage for Bewick's Wrens.

Breeding Dispersal by Birds in a Dynamic Urban Ecosystem.

Changes in land cover during urbanization profoundly affect the diversity of bird communities, but the demographic mechanisms affecting diversity are poorly known. We advance such understanding by documenting how urbanization influences breeding dispersal—the annual movement of territorial adults—of six songbird species in the Seattle, WA, USA metropolitan area. We color-banded adults and mapped the centers of their annual breeding activities from 2000–2010 to obtain 504 consecutive movements by 337 adults. By comparing movements, annual reproduction, and mate fidelity among 10 developed, 5 reserved, and 11 changing (areas cleared and developed during our study) landscapes, we determined that adaptive breeding dispersal of sensitive forest species (Swainson’s Thrush and Pacific wren), which involves shifting territory and mate after reproductive failure, was constrained by development. In changing lands, sensitive forest specialists dispersed from active development to nearby forested areas, but in so doing suffered low annual reproduction. Species tolerant of suburban lands (song sparrow, spotted towhee, dark-eyed junco, and Bewick’s wren) dispersed adaptively in changing landscapes. Site fidelity ranged from 0% (Pacific wren in changing landscape) to 83% (Bewick’s wren in forest reserve). Mate fidelity ranged from 25% (dark-eyed junco) to 100% (Bewick’s wren). Variation in fidelity to mate and territory was consistent with theories positing an influence of territory quality, asynchronous return from migration, prior productivity, and reproductive benefits of retaining a familiar territory. Costly breeding dispersal, as well as reduced reproductive success and lowered survival cause some birds to decline in the face of urbanization. In contrast, the ability of species that utilize edges and early successional habitats to breed successfully, disperse to improve reproductive success after failure, and survive throughout the urban ecosystem enables them to maintain or increase population size.

Avian occupancy varies with habitat structure in oak savanna of the south-central United States

Oak savanna, once widespread across central North America, has functionally vanished from most of its range because of land conversion or fire suppression, but much oak savanna remains in the Cross Timbers ecoregion of the south-central United States. We quantified avian habitat associations across a gradient from open oak savanna to woodland, to closed canopy forest in the Cross Timbers of southeastern Kansas. We surveyed breeding bird species in 2012 and 2013 and modeled species-specific occupancy in relation to habitat variables. Several species, including the northern bobwhite (Colinus virginianus), yellow- billed cuckoo (Coccyzus americanus), downy woodpecker (Picoides pubescens), Bewick's wren (Thryomanes bewickii), northern mockingbird (Mimus polyglottos), field sparrow (Spizella pusilla), dickcissel (Spiza americana), and orchard oriole (Icterus spurius) were associated with lower levels of tree density or canopy cover (i.e., savanna-woodland). Species associated with greater levels of tree density or canopy cover at some spatial scale included eastern wood-pewee (Contopus virens), white-breasted nuthatch (Sitta carolinensis), blue-gray gnatcatcher (Polioptila caerulea), and indigo bunting (Passerina cyanea). Occupancy of eastern wood-pewee and blue grosbeak (Passerina caerulea) were highest at intermediate levels of canopy cover (50- m radius) and tree density, respectively. Occupancies of eastern wood-pewee, northern mockingbird, lark sparrow (Chondestes grammacus), indigo bunting, and brown-headed cowbird (Molothrus ater )w ere variously related to shrub density, which was unrelated to tree cover or density across the savanna-forest gradient. We expect the savanna-associated species would benefit from reduction in tree density to savanna-like habitat (tree canopy cover � 25%) within forests that were formerly savanna. 2015 The Wildlife Society.

Widespread Dispersal of Borrelia burgdorferi–Infected Ticks Collected from Songbirds Across Canada

Millions of Lyme disease vector ticks are dispersed annually by songbirds across Canada, but often overlooked as the source of infection. For clarity on vector distribution, we sampled 481 ticks (12 species and 3 undetermined ticks) from 211 songbirds (42 species/subspecies) nationwide. Using PCR, 52 (29.5%) of 176 Ixodes ticks tested were positive for the Lyme disease spirochete, Borrelia burgdorferi s.l. Immature blacklegged ticks, Ixodes scapularis , collected from infested songbirds had a B. burgdorferi infection prevalence of 36% (larvae, 48%; nymphs, 31%). Notably, Ixodes affinis is reported in Canada for the first time and, similarly, Ixodes auritulus for the initial time in the Yukon. Firsts for bird-parasitizing ticks include I. scapularis in Quebec and Saskatchewan. We provide the first records of 3 tick species cofeeding on passerines (song sparrow, Swainson's thrush). New host records reveal I. scapularis on the blackpoll warbler and Nashville warbler. We furnish the following first Canadian reports of B. burgdorferi-positive ticks: I. scapularis on chipping sparrow, house wren, indigo bunting; I. auritulus on Bewick's wren; and I. spinipalpis on a Bewick's wren and song sparrow. First records of B. burgdorferi-infected ticks on songbirds include the following: the rabbit-associated tick, Ixodes dentatus, in western Canada; I. scapularis in Quebec, Saskatchewan, northern New Brunswick, northern Ontario; and Ixodes spinipalpis (collected in British Columbia). The presence of B. burgdorferi in Ixodes larvae suggests reservoir competency in 9 passerines (Bewick's wren, common yellowthroat, dark-eyed junco, Oregon junco, red-winged blackbird, song sparrow, Swainson's thrush, swamp sparrow, and white-throated sparrow). We report transstadial transmission (larva to nymph) of B. burgdorferi in I. auritulus. Data suggest a possible 4-tick, i.e., I. angustus, I. auritulus, I. pacificus, and I. spinipalpis, enzootic cycle of B. burgdorferi on Vancouver Island, British Columbia. Our results suggest that songbirds infested with B. burgdorferi-infected ticks have the potential to start new tick populations endemic for Lyme disease. Because songbirds disperse B. burgdorferi-infected ticks outside their anticipated range, health-care providers are advised that people can contract Lyme disease locally without any history of travel.

Song learning, dialects, and dispersal in the bewick's wren.

Zusammenfassung Junge Thryomanes bewickii wurden im William L. Finley National Wildlife Refuge by Corvallis, Oregon, USA, untersucht. Sie werden nach etwa 35 Tagen von ihren Eltern unabhangig. Elf ♂♂ waren auf eine durchschnittliche Entfernung von 1,2 km verstreut (im Bereich von 0,1 bis 3,2 km). Vier ♂♂ (60, 80, 110 und 135 Tage alt) auserten Jugendgesang (subsong) in Revieren, die sie lebenslang besetzt hielten. 60 Tage ist hochstwahrscheinlich das durchschnittliche Alter fur Reviergrundung und Beginn des Jugendgesangs. Das durchschnittliche Lied-Repertoire von 31 ausgewachsenen ♂♂ bestand aus 16 Liedtypen. Jeder Liedtyp bestand aus einer stabilen und mehrmals wiederholten Sequenz, die 2—5 melodische Themen hat (Anhaufungen von Noten oder Trillern). Der Jugendgesang des 60 Tage alten ♂ enthielt etwa 95 % der Themen des Repertoires eines Erwachsenen; bei einem zweiten Vogel waren alle Typen von Themen und Sequenzen im Alter von 115 Tagen vollstandig ausgebildet. Ein Thema oder hochstens ein ganzer Liedtyp, der sich bei einem jungen ♂ entwickelt, mus — wie Ahnlichkeitsvergleiche zeigen — auf Erfahrungen beruhen, die das Tier vor Grundung seines Reviers gemacht hat. Die meisten Liedtypen im Repertoire sind jedoch vergleichbar mit den Liedern der ♂♂, die unmittelbare Nachbarn des neu gegrundeten Reviers sind. Folglich ist die Bereitschaft zum Lernen von Themen und Sequenzen am grosten, einige Zeit nachdem sie von ihren Eltern unabhangig werden (35 Tage), jedoch vor dem Beginn des Jugendgesangs (60 Tage). Wahrend der Gesangs-Entwicklung lernen junge ♂♂ die Lieder Erwachsener, mit denen sie haufigen und engen Kontakt haben. Da die Reviere, die wahrend der Entwicklung des Liedes gegrundet wurden, dauerhaft sind und wahrend des ubrigen Jahres verteidigt werden, sind die Repertoires der Nachbar-♂♂ beinahe identisch. Einige Junge uberqueren geringe Populations-Barrieren, die dann den akustischen Kontakt mit ♂♂ der anderen Seite verringern. Lernen neuer Lieder kommt deshalb beschrankt vor. Die Variationen kommen zustande durch mangelhaftes Nachahmen eines Liedes, vielleicht auch durch Improvisation oder “Drift”. Darum fehlen viele Lieder, die an einer Stelle haufig sind, anderswo, auch ganz in der Nahe, vollkommen.

Avian Nest Box Selection and Nest Success in Burned and Unburned Southwestern Riparian Forest

ABSTRACT Riparian forest communities in the southwestern United States were historically structured by a disturbance regime of annual flooding. In recent decades, however, frequency of flooding has decreased and frequency of wildfires has increased. Riparian forests provide important breeding habitat for a large variety of bird species, and the effects of this altered disturbance regime on birds and their breeding habitat is largely unknown. To evaluate effects of high‐intensity spring and summer wildfire on the quality of breeding bird habitat in the Middle Rio Grande valley, we measured vegetation structure and composition, avian nest use, and nest success at 4 unburned plots and 4 wildfire plots over a 3‐year period. We measured avian nest use and success at nest boxes located in unburned riparian forest plots and plots recently burned by wildfire. Recent wildfire plots (<7 yr after fire) had a much different vegetation structure than unburned plots; an older (>7 yr after fire) wildfire plot more closely resembled its paired unburned plot than did recently burned plots. Ash‐throated flycatchers (Myiarchus cinerascens) and Bewick's wrens (Thryomanes bewickii; hereafter, flycatchers and wrens, respectively) used nest boxes in most of the plots. A model selection procedure applied to logistic regressions showed that frequency of nest box use by flycatchers was positively associated with wildfire, although flycatchers used boxes in unburned plots as well. Wrens showed a preferential use of nest boxes that were in unburned sites and in close proximity to vegetative cover. Growth rates, feeding rates, and fledging mass of flycatchers were similar in wildfire and unburned plots. Growth rates for wrens were slower in wildfire plots, while feeding rates and fledging mass were similar. Nest predation varied between years, was higher for flycatchers than for wrens, and was not directly influenced by wildfire. Model selection showed that predation increased with grass cover, an indicator of forest openness, and decreased with distance to habitat edge. Recovery of dense vegetation appears important in maintaining populations of Bewick's wrens, whereas ash‐throated flycatchers were less sensitive to vegetative structure and composition of postfire succession. Postfire management that maintains nest sites in large forest strips would enhance nesting density and success of these cavity‐nesting birds in riparian zones.

EFFECTS OF FOOD SUPPLEMENTATION ON FEMALE NEST ATTENTIVENESS AND INCUBATION MATE FEEDING IN TWO SYMPATRIC WREN SPECIES

We examined effects of incubation mate feeding on female incubation behavior and correlates of fitness by providing female Bewick's Wrens (Thryomanes bewickii) and House Wrens (Troglodytes aedon) with food supplements. Males of these species vary in their rates of feeding; Bewick's Wrens feed their incubating mates frequently, whereas House Wrens seldom engage in this behavior. Average length of incubation bout and nest attentiveness (proportion of time spent on the nest) were higher for supplemented female Bewick's Wrens and House Wrens compared to controls. Furthermore, mates of supplemented Bewick's Wrens provisioned females at lower rates than controls, and their rate of feeding was inversely correlated with ambient temperature. Incubation length and hatching success were not significantly different between treatments for either species. These results suggest that incubation mate feeding can increase female nest attentiveness and perhaps enhance fitness of both males and females. In House Wrens, potential tradeoffs between the benefits of parental care and opportunities to obtain additional mates may explain why males rarely feed incubating females.

Serologic evidence of West Nile Virus infection in birds, Tamaulipas State, México.

Following the introduction of West Nile virus (WNV) into North America in 1999, surveillance for WNV in migratory and resident birds was established in Tamaulipas State, northern México in December 2001. Overall, 796 birds representing 70 species and 10 orders were captured and assayed for antibodies to WNV. Nine birds had flavivirus-specific antibodies by epitope-blocking enzyme-linked immunosorbent assay; four were confirmed to have antibody to WNV by plaque reduction neutralization test. The WNV-infected birds were a house wren, mourning dove, verdin and Bewick's wren. The house wren is a migratory species; the other WNV-infected birds are presumably residents. The WNV-infected birds were all captured in March 2003. These data provide the first indirect evidence of WNV transmission among birds in northern México.

FACTORS INFLUENCING EXPANSION OF THE BREEDING DISTRIBUTION OF BEWICK'S WREN INTO RIPARIAN FORESTS OF THE RIO GRANDE IN CENTRAL NEW MEXICO

Abstract In central New Mexico, breeding populations of Bewick's wren (Thryomanes bewickii) recently colonized riparian forests of the Middle Rio Grande and have increased rapidly to become the sixth most abundant breeding bird species in bosque habitats. In 1997–1998, I studied the potential roles that cottonwood forest succession and alien plant species invasion might have had in facilitating this change in the distribution of the wren. Habitat preference and nest cavity limitation were examined at 12 sites near Albuquerque, New Mexico. Bewick's wrens nested only in native tree species, especially large cottonwoods (Populus deltoides). Territories defended by males had greater coverage of mature cottonwood and lower amounts of open, early successional habitats than areas not occupied by wrens. Analysis of wren abundance data from 70 sites throughout the Middle Rio Grande found wren abundance to be highest at sites dominated by cottonwoods, especially at sites having alien salt cedar (Tamarix chinensis) ...

Habitat Preferences of Pinyon-Juniper Specialists Near the Limit of Their Geographic Range

Abstract We investigated habitat preferences for five pinyon-juniper specialists during the 1998 and 1999 breeding seasons in Utah juniper (Juniperus osteosperma) woodlands of southwestern Wyoming. We compared avian use and availability of vegetation features using univariate and multivariate analysis to detect selection for vegetative features of pinyon-juniper specialists near the northeastern range boundary of pinyon-juniper habitat on the Colorado Plateau. Gray Flycatchers (Empidonax wrightii), Juniper Titmice (Baeolophus griseus), and Bewick's Wrens (Thryomanes bewickii) preferred woodlands with high overstory juniper cover. The Juniper Titmouse was associated with senescent trees, Blue-gray Gnatcatcher (Polioptila caerulea) with rock outcrops and shrubs in the family Rosaceae, and Black-throated Gray Warbler (Dendroica nigrescens) with pinyon pine (Pinus edulis). We suggest the geographic distribution of four of five pinyon-juniper specialists is limited by the occurrence of pinyon pine in semiarid woodlands on the northeastern Colorado Plateau. The geographic limit for Blue-gray Gnatcatchers in this region may correspond to the presence of mountain mahogany in the woodland understory. The conservation of pinyon-juniper specialists in southwestern Wyoming will benefit from the maintenance of successional processes, particularly those that perpetuate mature woodlands with a pinyon pine component.

HABITAT PREFERENCES OF PINYON-JUNIPER SPECIALISTS NEAR THE LIMIT OF THEIR GEOGRAPHIC RANGE1

Abstract We investigated habitat preferences for five pinyon-juniper specialists during the 1998 and 1999 breeding seasons in Utah juniper (Juniperus osteosperma) woodlands of southwestern Wyoming. We compared avian use and availability of vegetation features using univariate and multivariate analysis to detect selection for vegetative features of pinyon-juniper specialists near the northeastern range boundary of pinyon-juniper habitat on the Colorado Plateau. Gray Flycatchers (Empidonax wrightii), Juniper Titmice (Baeolophus griseus), and Bewick's Wrens (Thryomanes bewickii) preferred woodlands with high overstory juniper cover. The Juniper Titmouse was associated with senescent trees, Blue-gray Gnatcatcher (Polioptila caerulea) with rock outcrops and shrubs in the family Rosaceae, and Black-throated Gray Warbler (Dendroica nigrescens) with pinyon pine (Pinus edulis). We suggest the geographic distribution of four of five pinyon-juniper specialists is limited by the occurrence of pinyon pine in semiarid ...

Fluctuating Populations of House Wrens and Bewick's Wrens in Foothills of the Western Sierra Nevada of California

In foothills of the western Sierra Nevada, 31 km east of Madera, California, we studied whether Bewick's Wrens (Thryomanes bewickii) tend to be excluded from an area occupied by House Wrens (Troglodytes aedon) as reported in several studies in the eastern United States. Neither point counts from 1985 to 1997 nor spot mapping from 1989 to 1993 suggests any interaction between these species. The study period included the most prolonged drought and the most severe period of winter weather in the 64-year climatological record from the study site. House Wren abundance was significantly related to the 4-year running average of annual precipitation and to the lowest temperature recorded in the winter months preceding survey counts. We speculate that House Wrens cannot maintain their numbers by local recruitment during droughts in the oak-pine woodlands that dominate our study area and that recovery of their population following droughts involves recruitment from other areas, probably riparian zones and other mesic habitats elsewhere in the Sierra foothills and Central Valley of California. There was no influence of precipitation on abundance of Bewick's Wrens and, although they apparently sustained heavy mortality during a period of extreme winter weather, their numbers otherwise were not related to the lowest temperature during the winter preceding counts.

Interference Competition from House Wrens as a Factor in the Decline of Bewick’s Wrens

Widespread declines in breeding populations of migratory songbirds have been attributed to the destruction of breeding habitat, destruction of overwintering habitat, interspecific brood parasitism by cowbirds, and increased rates of predation on nests (Wilcove 1985; Terborgh 1989; Askins et al. 1990; papers in Hagan & Johnson 1992). Evidence for interspecific competition as a cause of decline is negligible (Terborgh 1989), although competition has been suspected as the cause of decline in Bewick's Wren (Thryomanes bewickii [Audubon]) (Wilcove 1990). Bewick's Wren, a songbird once found across much of the U.S., is on the Blue List (species of concern) of the National Audubon Society (Ehrlich et al. 1992), and Breeding Bird Surveys show declines in Bewick's Wrens from 1966 to 1991 in several parts of the country. Declines have been most notable in the migratory, eastemmost subspecies, the Appalachian Bewick's Wren (T. b. altus). The Appalachian Bewick's Wren once bred from eastern Kentucky, eastern Ohio, and Pennsylvania, south to Alabama and Georgia, and it was considered common or abundant in most of that region (Bent 1948). Over the past century the Appalachian Bewick's Wren has almost disappeared; during the 1980s only 20 pairs of Bewick's Wrens were found in Maryland, Virginia, and West Virginia combined (Maryland Natural Heritage Program 1989). In 1986 the Maryland Natural Heritage Program petitioned the U.S. Fish and Wildlife Service (UJSFWS) to list the Appalachian population of Bewick's Wren as endangered (Bartgis 1986). The USFWS accepted the petition (Maryland Natural Heritage Program 1989) but ranked the Appalachian population of Bewick's Wren

Asynchrony of song series in the Bewick's wren and wrentit

Asynchrony of song series in the Bewick's wren and wrentit

Geographic variation in songs of the Bewick's wren: a search for correlations with avifaunal complexity

Song characteristics of the Bewick's wren (Thryomanes bewickii) are compared from nine localities in the western United States. Character shifts, i.e., a difference in means, are evident for all song characters: Arizona and Colorado songs are especially short and long, respectively (Figs. 1, 2); songs of insular (Santa Cruz Is.) and nearby mainland populations in California are very dissimilar (Table 1); excluding the insular population, the frequency range of song phrases is positively correlated with latitude (Fig. 3). Variance shifts, i.e., a difference in repertoire size or Coefficients of Variation (CV's) of measured song characters, are also present; most notably, Arizona males have exceptionally stereotyped songs, with small song phrase repertoires (Table 2) and low CV's. Population densities and/or habitat structure undoubtedly influence signal design, but correlations reported here suggest that the avifaunal complexity and the corresponding vocal milieu should also be examined rigorously as possibly important influences.

Interspecific Territoriality between Bewick's and House Wrens

Interspecific Territoriality between Bewick's and House Wrens

Let's Make Bird Names Helpful

some changes a few years ago, they changed the name of the blue-headed vireo to the solitary vireo and, the American egret to the common egret. This kind of change is not inspired. All changes should be useful and significant. A clear goal is needed. Some names of bird species help in identification the chestnut-sided warbler; other names do not the Bewick's wren. I suggest this goal: change the unhelpful to helpful names. Many people have become birdwatchers only because someone encouraged them at the start to connect a name like Bell's vireo with a tiny, dull bird which doesn't look or act like a Bell or bell. A veritable thorn-hedge of such names creates a barrier which soon discourages many who might otherwise take an interest in bird-watching. We should do all we can to assist beginners. Breaking the name barrier would be a significant step. How many school children would learn the difference between a whitetailed deer and mule deer if these species were named Leconte's deer and Lichtenstein's deer? Since we use descriptive names for most mammals, why should we perpetuate nondescriptive names for so many birds? Beginners are not the only ones who could benefit by an improvement in the names of birds. In these days of increased travel, bird-watching can become an international sport if we give each species a name which will help to identify it on an international level. The white-winged dove is a perfect example, lending its name readily to Fig. 1. Black-crowned oriole. The old name, Bullock's oriole, does not help an inexperienced bird-watcher.