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At least 289 records · Page 16Linked to original sources
USGS2003

Effects of implanted radio transmitters with percutaneous antennas on the behavior of Canada Geese

We examined whether surgically-implanted radio transmitters with percutaneous antennas affected behavior of Lesser Canada Geese (Branta canadensis parvipes) in Anchorage, Alaska. We implanted either a 26-g VHF radio transmitter or a larger VHF radio that was the same mass (35 g) and shape as a satellite transmitter in the coelom of adult females captured during molt in 2000. A control group of females was marked with leg bands. We simultaneously observed behavior of radio-marked and control females from 4-62 d following capture. We observed no differences in the proportion of time birds in different treatments allocated among grazing, resting, comfort, walking, and alert behavior. Females in different treatments spent a similar proportion of time in the water. Implantation of radio transmitters did not affect the frequency of agonistic interactions. We conclude that coelomic radio transmitters with percutaneous antennas had minimal effects on the behavior of Canada Geese.

Alaska↗
USGS2003

Morphological traits of Pacific Flyway Canada Geese as an aid to subspecies identification and management

Subspecies of Canada Geese ( Branta canadensis ) exhibit wide variation in body size across their range. To monitor harvest levels in the Pacific Flyway, biologists commonly use culmen length and plumage color to differentiate among subspecies on sympatric wintering grounds. Among the four large-bodied Pacific subspecies ( B. c. parvipes , B. c. occidentalis , B. c. fulva , and B. c. moffitti ), overlap in culmen length and subjectivity of visually assessing color results in misclassification and inaccurate harvest estimates. We examined the morphology of Pacific large-bodied Canada Geese to characterize body size variation among subspecies and provide more discriminatory measures for harvest assessments. We found that culmen length, one of the most commonly used field measures, overlapped widely among subspecies, and it had little support for inclusion in discriminatory models. Morphological measures with greater explanatory power included bill width at nail, bill width at base, head length, and mid wing. If culmen length and plumage color continue to be used to assess winter harvest, we recommend the addition of at least one sex-specific measurement to reduce levels of misclassification among subspecies. If an additional morphological measure is included, further evaluation on the wintering grounds should be conducted as this measure's effectiveness may vary depending upon observer bias, temporal and spatial variation in subspecies abundance, and the proportion of birds accurately sexed by cloacal examination.

Pacific Flyway↗
USGS2003

Time-lapse video sysem used to study nesting Gyrfalcons

We used solar-powered time-lapse video photography to document nesting Gyrfalcon ( Falco rusticolus ) food habits in central West Greenland from May to July in 2000 and 2001. We collected 2677.25 h of videotape from three nests, representing 94, 87, and 49% of the nestling period at each nest. The video recorded 921 deliveries of 832 prey items. We placed 95% of the items into prey categories. The image quality was good but did not reveal enough detail to identify most passerines to species. We found no evidence that Gyrfalcons were negatively affected by the video system after the initial camera set-up. The video system experienced some mechanical problems but proved reliable. The system likely can be used to effectively document the food habits and nesting behavior of other birds, especially those delivering large prey to a nest or other frequently used site.

Kangerlussuaq↗
USGS2004

Determining nest predators of the Least Bell's Vireo through point counts, tracking stations, and video photography

We compared three methods to determine nest predators of the Least Bell's Vireo ( Vireo bellii pusillus ) in San Diego County, California, during spring and summer 2000. Point counts and tracking stations were used to identify potential predators and video photography to document actual nest predators. Parental behavior at depredated nests was compared to that at successful nests to determine whether activity (frequency of trips to and from the nest) and singing vs. non-singing on the nest affected nest predation. Yellow-breasted Chats ( Icteria virens ) were the most abundant potential avian predator, followed by Western Scrub-Jays ( Aphelocoma californica ). Coyotes ( Canis latrans ) were abundant, with smaller mammalian predators occurring in low abundance. Cameras documented a 48% predation rate with scrub-jays as the major nest predators (67%), but Virginia opossums ( Didelphis virginiana , 17%), gopher snakes ( Pituophis melanoleucus , 8%) and Argentine ants ( Linepithema humile , 8%) were also confirmed predators. Identification of potential predators from tracking stations and point counts demonstrated only moderate correspondence with actual nest predators. Parental behavior at the nest prior to depredation was not related to nest outcome.

Journal of Field Ornithology↗
USGS2004

Brown-headed Cowbird parasitism of the Black-throated Sparrow in central Arizona

From 1994-1996 we investigated effects of Brown-headed Cowbird ( Molothrus ater ) parasitism on Black-throated Sparrow ( Amphispiza bilineata ) nesting success in the Verde Valley of central Arizona. Of 56 Black-throated Sparrow nests, 52% were parasitized. Black-throated Sparrows appear to respond to natural parasitism by accepting the cowbird egg, deserting the nest, or burying the cowbird egg. Removal and damage of host eggs by female cowbirds effectively reduced clutch size from an average of 3.4 to 1.9 eggs. Because of this reduced clutch size, Black-throated Sparrow reproductive success was significantly lower in parasitized nests (0.2 young fledged/ nest) as compared to nonparasitized nests (1.6 young fledged/nest). When comparing cowbird parasitism between two habitat types, we found significantly higher parasitism frequencies in crucifixion-thorn ( Canotia holacantha ) versus creosote-bush ( Larrea divaricata ) habitat. We argue that this difference in parasitism is due to the greater number of tall perches (e.g., shrubs >4 m) available in crucifixion-thorn habitat, providing vantage points for female cowbirds to better find Black-throated Sparrow nests.

Arizona↗
USGS2004

Nest-site selection and hatching success of waterbirds in coastal Virginia: Some results of habitat manipulation

Rising sea levels in the mid-Atlantic region pose a long-term threat to marshes and their avian inhabitants. The Gull-billed Tern ( Sterna nilotica ), Common Tern ( S . hirundo ), Black Skimmer ( Rynchops niger ), and American Oystercatcher ( Haematopus palliatus ), species of concern in Virginia, nest on low shelly perimeters of salt marsh islands on the Eastern Shore of Virginia. Marsh shellpiles are free of mammalian predators, but subject to frequent floods that reduce reproductive success. In an attempt to examine nest-site selection, enhance habitat, and improve hatching success, small ( 2 × 2 m ) plots on five island shellpiles were experimentally elevated, and nest-site selection and hatching success were monitored from 1 May to 1 August, 2002. In addition, location, elevation, and nesting performance of all other nests in the colonies were also monitored. No species selected the elevated experimental plots preferentially over adjacent control plots at any of the sites. When all nests were considered, Common Tern nests were located significantly lower than were random point elevations at two sites, as they tended to concentrate on low-lying wrack. At two other sites, however, Common Tern nests were significantly higher than were random points. Gull-billed Terns and American Oystercatchers showed a weak preference for higher elevations on bare shell at most sites. Hatching success was not improved on elevated plots, despite the protection they provided from flooding. Because of a 7 June flood, when 47% of all nests flooded, hatching success for all species was low. Nest elevation had the strongest impact on a nest's probability of hatching, followed by nest-initiation date. Predation rates were high at small colonies, and Ruddy Turnstones ( Arenaria interpres ) depredated 90% of early Gull-billed Tern nests at one shellpile. The importance of nest elevation and flooding on hatching success demonstrates the potential for management of certain waterbird nesting sites. Facing threats from predators on barrier islands and rising sea levels especially in the mid-Atlantic region, several species of nesting waterbirds may benefit dramatically with modest manipulation of even small habitat patches on isolated marsh islands.

Virginia↗
USGS2005

A technique to produce aluminum color bands for avian research

We developed a technique to produce metal (aluminum) color bands, in response to concerns about leg injuries caused by celluloid-plastic color bands applied to Willow Flycatchers ( Empidonax traillii ). The technique involves color-anodized aluminum bands (unnumbered blanks and federal numbered bands), with auto pin-striping tape and flexible epoxy sealant, to create a variety of solid, half- and triple-split colors. This allows for hundreds of unique, high-contrast color combinations. During six consecutive years of application, these colored metal bands have resisted color fade compared to conventional celluloid-plastic bands, and have reduced leg injuries in the flycatcher. Although not necessarily warranted for all color-banding studies, these metal bands may provide a lower-impact option for studies of species known to be impacted by plastic color bands.

Journal of Field Ornithology↗
USGS2005

Geographic variation in survival and migratory tendency among North American Common Mergansers

Movement ecology and demographic parameters for the Common Merganser ( Mergus merganser americanus ) in North America are poorly known. We used band-recovery data from five locations across North America spanning the years 1938–1998 to examine migratory patterns and estimate survival rates. We examined competing time-invariant, age-graduated models with program MARK to study sources of variation in survival and reporting probability. We considered age, sex, geographic location, and the use of nasal saddles on hatching year birds at one location as possible sources of variation. Year-of-banding was included as a covariate in a post-hoc analysis. We found that migratory tendency, defined as the average distance between banding and recovery locations, varied geographically. Similarly, all models accounting for the majority of variation in recovery and survival probabilities included location of banding. Models that included age and sex received less support, but we lacked sufficient data to adequately assess these parameters. Model-averaged estimates of annual survival ranged from 0.21 in Michigan to 0.82 in Oklahoma. Heterogeneity in migration tendency and survival suggests that demographic patterns may vary across geographic scales, with implications for the population dynamics of this species.

Journal of Field Ornithology↗
USGS2005

Use of radio-telemetry to reduce bias in nest searching

We used traditional searching, as well as radio-telemetry, to find 125 Wood Thrush ( Hylocichla mustelina ) nests during 1994–1996 at the Piedmont National Wildlife Refuge in Georgia, USA. We compared daily nest survival rates for 66 nests of radio-marked birds with 59 nests of birds found through systematic searching. By using radio-telemetry, we found Wood Thrush nests in higher elevation pine habitats, in addition to the more usual hardwood forests with moist soils. We found nests of radio-marked birds farther from streams than nests found by systematic searching. Thirty-two percent of radio-marked birds' nests were found at the tops of slopes, compared to 15% of the nests found by traditional searching. In addition, radio-marked birds generally moved up-slope for re-nesting attempts. Although the distribution of nests found with telemetry and searching varied, daily nest survival did not vary between the two groups. Radio-telemetry provided new information about Wood Thrush nesting habitats. We believe radio-telemetry can be a valuable addition to traditional searching techniques; it has the potential to provide a sample of nests free from a priori habitat biases.

Georgia↗
USGS2005

A simple, inexpensive video camera setup for the study of avian nest activity

Time-lapse video photography has become a valuable tool for collecting data on avian nest activity and depredation; however, commercially available systems are expensive (>USA $4000/unit). We designed an inexpensive system to identify causes of nest failure of American Oystercatchers ( Haematopus palliatus ) and assessed its utility at Cumberland Island National Seashore, Georgia. We successfully identified raccoon ( Procyon lotor ), bobcat ( Lynx rufus ), American Crow ( Corvus brachyrhynchos ), and ghost crab ( Ocypode quadrata ) predation on oystercatcher nests. Other detected causes of nest failure included tidal overwash, horse trampling, abandonment, and human destruction. System failure rates were comparable with commercially available units. Our system's efficacy and low cost (<$800) provided useful data for the management and conservation of the American Oystercatcher.

Georgia↗
USGS2017

Tell me a story! A plea for more compelling conference presentations

Effective communication with other scientists is an essential component of the scientific process, underlying success in publishing papers, building collaborations, securing grants and jobs, and stimulating further research. Oral presentations at professional meetings provide an opportunity to share research findings with a relatively broad scientific audience. However, many scientists give talks that are crowded with methods and data, accompanied by poor visuals, and, most unfortunately, lacking in narrative arc. Here, I provide strategies for distilling research findings into a short-format talk, capturing the audience's attention, and delivering a compelling and visually engaging story. I argue that the material should be designed to interest a wide range of meeting attendees, not just experts in a narrow field. I also advocate principles of good storytelling, with the aim of leading the audience through a compelling journey of discovery that concludes with a memorable takeaway message.

The Condor: Ornithological Applications↗
USGS2018

Fine-scale heterogeneity drives forest use by spring migrant landbirds across a broad, contiguous forest matrix

Much of our understanding of en route landbird habitat use comes from research performed at local scales, ignoring effects at larger spatial scales. We used a multiscale approach to investigate stopover habitat use by landbirds using transect surveys in 68 forested sites in southwestern Michigan, USA, during the springs of 2002 and 2003. We modeled relationships of bird density and arthropod abundance with broad-scale spatiotemporal factors (year, day of year, geographic location) and local landscape (forest composition and structure, presence of open water) as well as site-scale factors (bird density and arthropod abundance, which exchanged roles as predictor and response variables). We found migrant densities to be most influenced by fine-scale factors, such as the abundance of other avian taxa and substrate arthropods, followed by broader-scale factors, such as forest structure and location, within the local and broader surrounding landscape. We found that migrant habitat associations either did not directly match or were weakly associated with the availability of riparian or lacustrine water habitats at a local scale, even though our results suggested that birds using these habitat cues would have encountered more arthropods. Rather than finding indirect measures of food abundance—such as distance to a water source or forest cover at the landscape scale—important, our models best explained bird density by a direct relationship with site-scale food resources. Thus, the scale at which migrants demonstrate habitat selection appears to be influenced by proximate mechanisms such as high-quality habitat availability and the presence of large ecological features within the landscape. Not only do factors operating at multiple scales influence how birds use habitats, but scale also influences how we interpret research findings, in turn influencing conservation decisions.

Michigan↗
USGS2015

Radio-transmitters have no impact on survival of pre-fledged American Woodcocks

American Woodcocks ( Scolopax minor ) are a high priority species of conservation need across most of their breeding range due to long-term population declines. Survival of juveniles may be key to understanding these population declines, but there have been few direct estimates of juvenile woodcock survival rates, and no recent assessment of the possible effect of radio-tagging on juvenile survival. In 2011 and 2012, we radio-tagged 73 juvenile American Woodcocks in west-central Minnesota and compared survival rates of radio-tagged ( N = 58) and non-radio-tagged ( N = 82) juveniles during the period from hatching to fledging. We compared survival rates of juveniles with known fates and used logistic-exposure models to assess the potential impact of radio-transmitters on survival. We evaluated variables related to juvenile survival including age, hatch date, maximum and minimum temperature, precipitation, and year to assess the possible effects of radio-transmitters. The best-supported model of survival rate of juvenile American Woodcocks included the interaction of age and year and a negative effect of precipitation (β = −0.76, 85% CI: −1.08 to −0.43), but did not include a negative effect of transmitters. Our results suggest that radio-transmitters did not impact survival of juvenile American Woodcocks and that transmitters are a reliable tool for studying survival of juvenile American Woodcocks, and perhaps other precocial shorebirds.

Journal of Field Ornithology↗
USGS2008

Timing and location of mortality of fledgling, subadult, and adult California Gulls

We investigated patterns of mortality during post-breeding migrations of California Gulls (Larus californicus) nesting near Laramie, Wyoming, USA. We used 151 recoveries and 647 sightings of banded and patagially-marked gulls to compare ratios of mortalities to observations of live birds (1) during four time periods (early and late fall migration, winter, and spring migration), (2) at two locations (Pacific coast and inland), and (3) among three age-classes of gulls (fledglings, 1- and 2-year-olds, and breeding-age adults). Mortality rates were higher in inland areas (35%) than in coastal areas (15%) and were dependent on season within inland areas, but not in coastal areas. Mortality in inland areas during early fall (21%) was comparable with that in coastal areas (13%) but was higher during late fall (68 vs. 13%) and spring migration (46 vs. 17%). Both fledgling (71%) and adult (64%) gulls experienced high mortality rates during late fall migration, possibly because some gulls were too weak to make their way to the Pacific coast and became trapped by poor weather conditions. Adult gulls also experienced high mortality inland during spring migration; few subadults made the costly migration to and from the breeding area. Some adults also skipped breeding and remained in coastal areas during the breeding season.

Wilson Journal of Ornithology↗
USGS2006

Insular and migrant species, longevity records, and new species records on Guana Island, British Virgin Islands

We conducted mist netting each October from 1994 to 2004 on Guana Island, British Virgin Islands, and recorded bird sightings to develop a more complete inventory of the island's resident and migrant species. During our study, we recorded four new species for the British Virgin Islands: Magnolia Warbler (Dendroica magnolia; 1996), Golden-winged Warbler (Vermivora chrysoptera; 1997), Swainson's Thrush (Catharus ustulatus; 2000), and Red-necked Phalarope (Phalaropus lobatus; 2004). Blackpoll Warbler (Dendroica striata) was the most frequently captured Neotropical migrant landbird, despite only being first detected in the region in 1989. Captures and detections of other Neotropical migrant landbirds suggest that many species may be more common in the region than previously believed, or, as speculated by other researchers, that migrant routes may be shifting eastward due to habitat degradation on western Caribbean islands. We also used recapture data to establish longevity records of resident species, including Caribbean Elaenia (Elaenia martinica; ??? 7 years), Bananaquit (Coereba flaveola; 7 years), Black-faced Grassquit (Tiaris bicolor; ???9 years), and Zenaida Dove (Zenaida aurita; 5 years). Longevities of other resident species were similar to, or slightly less than, those reported elsewhere.

Wilson Journal of Ornithology↗
USGS2006

Golden-cheeked warbler males participate in nest-site selection

Nest-site selection behaviors have rarely been described for songbirds. Furthermore, male involvement in nest-site selection is generally assumed to be minimal among most species, especially those predominantly exhibiting female nest building. This assumption has held true for the federally endangered Golden-cheeked Warbler (Dendroica chrysoparia), a breeding resident of central Texas. We observed Golden-cheeked Warbler males and females searching for nest sites together on three separate occasions, 2001-2003. Although rare, such observations add to our knowledge of the life history of songbirds.

Wilson Journal of Ornithology↗
USGS2007

Habitat relationships of birds overwintering in a managed coastal prairie

Grassland birds are considered to be rapidly declining in North America. Management approaches for grassland birds frequently rely on prescribed burning to maintain habitat in suitable condition. We evaluated the relationships among years since burn, vegetation structure, and overwintering grassland bird abundance in coastal prairie. Le Conte's Sparrows (Ammodramus leconteii) were most common in areas that had: (1) been burned within the previous 2 years, (2) medium density herbaceous vegetation, and (3) sparse shrub densities. Savannah Sparrows (Passerculus sandwichensis) were associated with areas: (1) burned within 1 year, (2) with sparse herbaceous vegetation, and (3) with sparse shrub densities. Sedge Wrens (Cistothorus platensis) were most common in areas that had: (1) burned greater than 2 years prior and (2) dense herbaceous vegetation. Swamp Sparrows (Melospiza georgiana): (1) were most common in areas of dense shrubs, (2) not related to time since burnings, and (3) demonstrated no relationship to herbaceous vegetation densities. The relationships to fire histories for all four bird species could be explained by the associated vegetation characteristics indicating the need for a mosaic of burn rotations and modest levels of woody vegetation.

Wilson Journal of Ornithology↗
USGS2007

First description of the nest, eggs, and breeding behavior of the Mérida Tapaculo ( Scytalopus meridanus )

We provide the first description of the nest, eggs, and breeding behavior of the M&eacute;rida Tapaculo ( Scytalopus meridanus ). Data are from one pair in the moist cloud forest of Yacambu National Park, Venezuela during April&ndash;May 2004. Two nests, constructed by the same pair, were globular in structure and consisted of mossy material placed in a rock crevice of a muddy rock wall. The eggs were cream colored with an average mass of 4.19 g. Clutch sizes were one in the first nest and two in the second. The species showed bi-parental care in nest building and incubation. Nest attentiveness (percent time spent on the nest incubating) averaged 83.4 &plusmn; 14% (SD). Average on and off bouts were 33.24 and 6.34 min, respectively.

Yacambu National Park↗