Vaux's Swifts Research Articles

MASS MORTALITY OF VAUX'S SWIFTS IN SOUTHERN OREGON

We describe a mass mortality event at a school in Medford, Oregon in which the remains of over 5600 Vaux's Swifts (Chaetura vauxi) were found at the bottom of a chimney. The use of operating chimneys by migratory aggregations of this species poses the risk of significant mortality. We offer suggestions to reduce the risk of Vaux's Swift mortality caused by operating chimneys and illustrate how community involvement can contribute to mortality reduction.

Annual 10-Month Aerial Life Phase in the Common Swift Apus apus

The common swift (Apus apus) is adapted to an aerial lifestyle, where food and nest material are captured in the air. Observations have prompted scientists to hypothesize that swifts stay airborne for their entire non-breeding period [1, 2], including migration into sub-Saharan Africa [3-5]. It is mainly juvenile common swifts that occasionally roost in trees or buildings before autumn migration when weather is bad [1, 6]. In contrast, the North American chimney swift (Chaetura pelagica) and Vaux's swift (C.vauxi) regularly settle to roost in places like chimneys and buildings during migration and winter [7, 8]. Observations of common swifts during the winter months are scarce, and roost sites have never been found in sub-Saharan Africa. In the breeding season, non-breeding individuals usually spend the night airborne [9], whereas adult nesting birds roost in the nest [1]. We equipped common swifts with a micro data logger with an accelerometer to record flight activity (years 1-2) and with a light-level sensor for geolocation (year 2). Our data show that swifts are airborne for >99% of the time during their 10-month non-breeding period; some individuals never settled, but occasional events of flight inactivity occurred in most individuals. Apparent flight activity was lower during the daytime than during the nighttime, most likely due to prolonged gliding episodes during the daytime when soaring in thermals. Our data also revealed that twilight ascents, previously observed during the summer [10], occur throughout the year. The results have important implications for understanding physiological adaptations to endure prolonged periods of flight, including the need to sleep while airborne.

Patterns of migratory connectivity in Vaux's Swifts at a northern migratory roost: A multi-isotope approach

ABSTRACT The strength of migratory connectivity between breeding, stopover, and wintering areas can have important implications for population dynamics, evolutionary processes, and conservation. For example, patterns of migratory connectivity may influence the vulnerability of species and populations to stochastic events. For many migratory songbirds, however, we are only beginning to understand patterns of migratory connectivity. We investigated the potential strength of migratory connectivity within a population of Vaux's Swifts (Chaetura vauxi). Like many aerial insectivores, this species is currently experiencing population declines. In 2012, a mass mortality event at a spring migratory roost on Vancouver Island, British Columbia, Canada, resulted in the deaths of >1,000 individuals (~2% of the British Columbia population). In these individuals, we examined variation in 3 stable isotopes (δ2H, δ13C, and δ15N) from claw samples to determine whether spring migrants showed inherent isotopic similarity in...

Linking Population Declines with Diet Quality in Vaux's Swifts

Over the past 50 years, a range of environmental stressors has resulted in aerial insectivores throughout North America experiencing sharp population declines. Vaux’s swifts (Chaetura vauxi) are small, long-distance migratory birds that are currently experiencing range-wide population declines, especially at the their northern range limit. Many studies attribute the Vaux’s swift’s population decline to a loss in nesting habitat; however, other potentially exacerbating factors, such as changes in insect composition and diet, remain unstudied. Here, we examine a ~26 year dietary archive of Vaux’s swift guano to ask whether diet composition has changed over time. Vaux’s swifts roost communally at the same roost sites each year when migrating, often within decommissioned brick chimneys. As a result, guano accumulates at the base of these roost sites, providing a chronostratified snapshot of the bird’s historic diet. We obtained a vertical core sample from a Vaux’s swift guano deposit in a chimney on Vancouver Island, BC, Canada. We symmetrically stratified the guano and assessed diet composition by visually analyzing egested arthropod exoskeletons, identifying them to order, and measuring δ15N signatures at each layer. Our 26-year data set revealed an increase in the ratio of Hemiptera to Coleoptera corresponding with an increase in δ15N, suggesting a possible decline in diet quality through time because Hemipterans tend towards higher trophic status than Coleopterans, but are of less caloric value per capita. In addition, δ15N was significantly negatively correlated with an annual population index (Breeding Bird Survey). We suggest a reduction in diet quality may be contributing to the decline of Vaux’s swift populations, and could be contributing to more declines in other aerial insectivore species.

Polydactyly in a Vaux's Swift

I report on polydactyly in a Vaux's Swift (Chaetura vauxi). An extra, asymmetrically located toe was found on each foot of one swift. A check of 329 swifts from several museums produced no other examples of polydactyly in this species. A review of the literature and a query over the Internet, however, produced 10 other examples of polydactyly in wild birds.

Use of nest boxes by Vaux's Swifts

The use of nest boxes by Vaux's Swifts (Chaetura vauxi) was investigated because of the loss of large-diameter hollow trees used for nesting in northwestern North America. Nest attempts and nest success were compared in nest boxes among three habitat types in northeastern Oregon. Air temperatures in the boxes were monitored to determine if boxes overheated and resulted in nestling mortality. Thirty of 103 nest boxes were used by nesting Vaux's Swifts for at least one year during 1999–2002. Of 51 nest attempts, 53% successfully fledged 1–6 young (x̄ = 3.5 nestlings). Over this 4-yr period, 47% of the nests were in late-seral stage grand fir (Abies grandis) stands, 31% were in harvested stands of grand fir, and 22% were in ponderosa pine (Pinus ponderosa) stands. It appeared that temperature did not affect nest success in boxes because there were no significant differences in maximum and minimum temperatures between successful and unsuccessful nest attempts. Nest boxes provided alternative nest sites for Vaux's Swifts in habitats traditionally used by this species as well as in habitats that currently lack natural nest sites.

Breeding Bird Community Composition in Relation to Riparian Vegetation Structure in the Western United States

Riparian zones, which are under increasing pressure by various users, provide sources of avian diversity in many landscapes of the semiarid West; however, there are few data available that address avian community composition in different riparian vegetation structures. We compared total abundance of diurnal breeding birds, individual bird species abundance, bird species richness, and vegetation composition and structure among streamside vegetation associations in Bear and Silvies valleys in eastern Oregon during 1993 and 1994. We collected bird and vegetation data along 4 replicate transects within each of 3 vegetation associations characterized by streamside vegetation structure: herbaceous xeric shrub, discontinuous mesic shrub, and continuous mesic shrub. Total bird abundance was greater (P < 0.001) in the continuous mesic shrub association than in the herbaceous xeric shrub and discontinuous mesic shrub associations during 1993 and 1994. Species richness was inconsistent between years among vegetation associations (P = 0.034); it was greatest (Ps ≤ 0.037) in the continuous and discontinuous mesic shrub associations in 1993, and greatest (Ps ≤ 0.003) in the continuous mesic shrub association in 1994. Yellow warbler (Dendroica petechia), song sparrow (Melospiza melodia), willow flycatcher (Empidonax traillii), American robin (Turdus migratorius), common snipe (Gallinago gallinago), bobolink (Dolichonyx oryzivorus), and Vaux's swift (Chaetura vauxi) were most abundant in the continuous mesic shrub association (Ps ≤ 0.088). Savannah sparrow (Passerculus sandwichensis), black tern (Chlidonias niger), and American wigeon (Anas americana) were most abundant in the herbaceous xeric shrub association (Ps ≤ 0.032). Yellow warblers, willow flycatchers, and song sparrows, which almost exclusively depend on hydrophytic shrub thickets for nesting in the semiarid western United States, are especially threatened by the elimination or simplification of continuous associations of mesic shrub vegetation. We recommend that continuous associations of mesic shrub vegetation be maintained'or restored where possible because this vegetation structure is associated with avian abundance, species richness, riparian-associate bird species abundance, and landscape-level biological diversity.

Diet and Foraging Behavior of Vaux's Swifts in Northeastern Oregon

The diet ofVaux's Swifts (Chaetura vauxi) during the breeding season consisted primarily of insects in the orders Homoptera (hoppers, aphids, whiteflies), Diptera (flies), Ephemeroptera (mayflies), and Hymenoptera (ants, parasitic wasps). Diet was determined from 223 food boluses collected from adults feeding nestlings and represented 24,133 individual insects and spiders. Diet did not differ among five study areas or by time of day. A pair of swifts feeds an average of 5,344 arthropods to their nestlings each day, and an average of 154,976 arthropods during the nestling growth period. Radio-tagged swifts foraged up to 5.4 km from the nest. Of actual sightings of radiotagged birds, 64% were foraging over land, 27% were foraging over water, and 9% were traveling in a straight line.

Summer Roosts and Roosting Behavior of Vaux's Swifts in Old-Growth Forests

BINFORD, L. C., B. G. ELLIOT, AND S. W. SINGER. 1975. Discovery of a nest and the downy young of the marbled murrelet. Wilson BU11. 87:303-319. HENDERSON, J. A., AND D. PETER. 1984. Preliminary plant associations and habitat types of the Darrington Ranger District, Mt. Baker-Snoqualmie National Forest. USDA For. Serv. Pacific Northwest Region Publ. 66 pp. HIRSCH, K. 01., D. A. WOODBY, AND L. B. ASTHEIMER. 1981. Growth of a nestling marbled murrelet. Condor 83:264-265. KIFF, L. 1981. Eggs of the marbled murrelet. Wilson Bull. 93:400-403. MARSHALL, D.B. 1988. The marbled murrelet joins the old growth conflict. Am. Birds 42(2):202212. SEALY, S. G. 1974. Breeding phenology and clutch size in the marbled murrelet. Auk 91:10-23. SIMONS, T. R. 1980. Discovery of a ground nesting marbled murrelet. Condor 82:1-9.

Spring and Winter Bird Populations in a Douglas-Fir Forest Sere

Changes in bird species richness, abundance, and guild structure were compared among young (42-75), mature (105-165), and oldgrowth (250-500+ years) and between winter and spring, for 2 years in Douglas-fir (Pseudotsuga menziesii) forests of the southern Washington Cascade Mountains. In winter, bird species richness, diversity, and abundance were all greater in oldgrowth than in younger stands. The most abundant species were the chestnut-backed chickadee (Parus rufescens), golden-crowned kinglet (Regulus satrapa), pine siskin (Carduelis pinus), and red crossbill (Loxia curvirostra). In spring, there were few differences in diversity and abundance along the stand age gradient. Species richness showed a slight increase from young to oldgrowth. The most abundant spring species were the winter wren (Troglodytes troglodytes), western flycatcher (Empidonax difficilis), varied thrush (Ixoreus naevius), hermit warbler (Dendroica occidentalis), and chestnut-backed chickadee. The Vaux's swift (Chaetura vauxi) exhibited the strongest association with oldgrowth in the spring. Seasonal changes in abundance were greater in young and mature stands than in oldgrowth. This pattern was most noticeable among permanent resident species. A more favorable microclimate and probably better foraging conditions in oldgrowth in winter may explain the observed seasonal patterns of abundance. J. WILDL. MANAGE. 51(3):586-595 Even though the importance of the breeding season has been strongly emphasized as shaping bird communities, the winter season may be equally critical (Fretwell 1972), especially in regions where large numbers of species occupy the habitat throughout the year. Seasonal population changes, particularly of permanent residents, may provide an indirect measure of habitat quality. Forests of different age may provide different levels of resources, and therefore, may vary in quality. The published accounts by Raphael (1984) and Raphael and Barrett (1984) provided comparable studies for late successional Douglas-fir forests in northern California. The purpose of our study was to document the seasonal changes in bird community structure within a sere of natural Douglas-fir forests and o speculate on the effects of forest management on bird communities during both the winter and breeding seasons. We express our appreciation to M. Q. Affolter, B. Booth, J. B. Buchanan, C. B. Chappell, M. This content downloaded from 157.55.39.123 on Tue, 18 Oct 2016 06:04:41 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 51(3):1987 BIRDS IN DOUGLAS-FIR * Manuwal and Huff 587 Emers, K. W. Hegstad, A. Hetherington, A. B. Humphrey, D. A. Leversee, R. W. Lundquist, J. M. Mariani, B. R. North, M. J. Reed, B. A. Schrader, and L. A. Willimont for assistance with the fieldwork. N. J. Manuwal, J. G. Dickson, R. W. Mannan, R. W. Lundquist, and J. B. Buchanan provided valuable comments on the manuscript. We thank J. M. Mariani for many long hours of data editing and calculation of detection rates for the winter 1984-85 data, and J. R. Osborne for his computer expertise. We thank U.S. For. Serv. personnel at the Wind River, St. Helens, Randle, and Packwood ranger districts and Mt. Rainier Natl. Park personnel for various assistance. We acknowledge the support of L. F. Ruggiero, A. B. Carey, and F. B. Samson. This study was funded by contracts PNW-83-219 and PNW-84-227 and is Contrib. 44 of the Old-growth Wild. Habitat Res. Pro-

Behavior of Vaux's Swifts Nesting and Roosting in a Chimney

Behavior of Vaux's Swifts Nesting and Roosting in a Chimney

Spruce Grouse Copulation

Vaux's Swift. Chaetura vauxi. A male (JSW no. 943) collected on 14 September 1969 was very fat, with a few pinfeathers, a large skull window (7 x 10 mm), and the testes 1/? X 2 mm. It was taken from a flock of seven Vaux's Swifts and is the first specimen from central Arizona (Phillips et al., loc. cit.:59). Mountain Chickadee. Parus gambeli. A female (JSW no. 974) collected 24 October 1970 is our only known specimen from the south-central Arizona lowlands. This individual with skull fully ossified, no fat, and ovaries 4 x 15 mm, was one of four seen that day. Rufous-backed Robin. Turdus rufopalliatus. Our specimen (JSW no. 927), collected on 30 November 1969, is an adult male, testes minute. It showed little fat and a few pinfeathers in the capital tract only. It was feeding alone on the grassy margin of a marsh even though there was a small flock of Robins (Turdus migratorius) in the area. This is approximately 175 mi. N of the specimen collected by Harrison (Auk 79:271, 1962). It is also apparently the second verifiable record for the United States, and the species, like the Groove-billed Ani, remains unrecorded in northern Sonora. Northern Water-thrush. Seiurus noveboracensis. A female? (JSW no. 969) taken on 30 August 1970 is the first collected from the lowlands of south-central Arizona since one taken at Phoenix by Breninger on 16 September 1897 (Phillips, pers. corr.). The specimen had heavy fat beneath the feather tracts, skull fully ossified, and no molt. American Redstart. Setophaga ruticilla. A young female (JSW no. 971) collected 30 August 1970 is the first record for central Arizona and one of few specimens for the state. The specimens showed skull windows, no molt, and moderate fat. Golden-crowned Sparrow. Zonotrichia atricapilla. A female (JSW no. 923) taken on 15 November 1969 is the first record from central Arizona (Phillips et al., loc. cit.:207) and one of the few specimens from the state. It had a few pinfeathers in the spinal tract, moderate fat, and ovary not enlarged (1% X 3 mm). Swamp Sparrow. Melospiza georgiana. A female (JSW no. 924), collected on 15 November 1969, was the first specimen from central Arizona, although there are others from the southern and western parts of the state (Phillips et al., loc. cit.:208-209). It had little fat, no molt, a large skull window (8 x 10 mm), and ovary not enlarged (2 X 3%/2 mm). Partial support for this study was provided by a Sigma Xi Grant-in-Aid of Research on the Ecology of the Salt River at the proposed Orme Dam site, Maricopa Co., Arizona.

Nesting and Nest Visitors of the Vaux's Swift in Montana

Nesting and Nest Visitors of the Vaux's Swift in Montana

Nesting of the Northern Vaux Swift in the Willamette Valley

Nesting of the Northern Vaux Swift in the Willamette Valley

Notes on the Black Swift and Vaux Swift at their nesting sites in central British Columbia

Notes on the Black Swift and Vaux Swift at their nesting sites in central British Columbia

Changing Habits of Vaux Swift and Western Martin

Two broods are evidently raised, as an immature bird, in company with an adult, was flushed on August 9. The nighthawks were noticeably less numerous during the latter part of the summer, and it is possible that the males and the young of the first brood left in July or earlier. The flight of the Texas Nighthawk gives the impression of ease to a greater degree than that of any other of our smaller birds. While not slow, it appears leisurely and is frequently varied by periods of gliding. The large expanse of wing gives great buoyancy and the bird seems to float through the air almost without effort, while a turn of the wing serves to change its course at an abrupt angle The Texas Nighthawk flies at a much lower altitude than is the usual habit of swallows and swifts. While hunting it never ascends to any great height, and often skims close to the ground, passing among the vegetation. In the evening its activities begin about sunset or earlier, usually ceasing before dark, and in the morning it is apt to remain in the air for some time after sunrise. It may sometimes be seen hunting at mid-day, especially in cloudy weather. The nighthawk displays some curiosity and often swoops down within a few feet of one's head. Even at that distance the flight is entirely inaudible. In general the vocal utterances of the Texas Nighthawk are of three kinds: first, a low soft cluck, repeated slowly; second, a louder, querulous, nasal cry, repeated more rapidly and used when two or more of the birds are together; third, a series of throaty staccato notes delivered in monotone so rapidly as to be almost continuous, sustained for several seconds at a time and resumed after a short pause as if for breath. This trill is sometimes given from the ground, and very frequently while flying. It is used only when the birds are undisturbed and is not ordinarily heard at close range. While the tone is soft, the carrying power is great, and sometimes on summer evenings when several of the nighthawks are about, the air seems filled with an indefinable vibration.

Some Notes on the Vaux Swift (Chactura vauxi) at Seattle, Wn.

Some Notes on the Vaux Swift (Chactura vauxi) at Seattle, Wn.

Among the Sea Birds of the Oregon Coast

BOUT forty miles south of the mouth of the Columbia River and two miles out from the entrance of Netarts Bay are three large rocks. These are the homes of countless numbers of sea-birds and as the bird life there had never been disturbed to any Netarts was one of interest to a bird crank because in the coast mountains we found breeding, such birds as the varied thrush, pileolated warbler, Oregon jay, Vaux swift, pileated woodpecker, western evening grosbeak and in the dwarfed shrubbery down by the