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Copyright of Avian Conservation & Ecology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Predation can play a significant role on survival during migration as birds find themselves competing for resources in unfamiliar habitats. Here we describe the first documented observation of a Buteo platypterus (Broad-winged Hawk) predating an Archilochus colubris (Ruby-throated Hummingbird) during autumn migration. To our knowledge, this is the first documented record of any Buteo sp. hawk predating any Trochilidae (hummingbird). While predation on hummingbirds likely represents a minor source of mortality, identifying sources of predation and mortality is important in understanding the risk of migration for any species. [ABSTRACT FROM AUTHOR]

Conservation planning for large ecosystems has multiple benefits but is often challenging to implement because of the multiple jurisdictions, species, and habitats involved. In addition, decision making at large spatial scales can be hampered because many approaches do not explicitly incorporate potentially competing values and concerns of stakeholders. After the Deepwater Horizon oil spill, establishing baselines was challenging because of (1) variation in study designs, (2) inconsistent use of explicit objectives and hypotheses, (3) inconsistent use of standardized monitoring protocols, and (4) variation in spatial and temporal scope associated with avian monitoring projects before the spill. Herein, we show how the Gulf of Mexico Avian Monitoring Network members used structured decision making to identify bird monitoring priorities. We used multiple tools and techniques to clearly define the problem and stakeholder objectives and to identify bird monitoring priorities at the scale of the entire northern Gulf of Mexico region. Although our example is specific to the northern Gulf of Mexico, this approach provides an example of how stakeholder values can be incorporated into the coordination process of broad-scale monitoring programs to address management, restoration, and scientific questions in other ecosystems and for other taxa. [ABSTRACT FROM AUTHOR]

Copyright of Auk: Ornithological Advances is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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 sitescale 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. [ABSTRACT FROM AUTHOR]

Organisms with limited motility may use animal transport as a mechanism for dispersal. Migratory birds can provide a vehicle to move small organisms great distances, which may allow them access to areas that are otherwise inaccessible. During normal mist netting operations at a spring migration banding station along the northern Gulf of Mexico coast in Louisiana, USA, we encountered an Indigo Bunting (Passerina cyanea) with numerous snails, possibly Galba cubensis, underneath its breast feathers. While encounters of songbirds carrying snails appear rare, long-distance migrating songbirds represent a possible mechanism to transport small snails great distances to expand ranges, colonize new areas, or maintain genetic continuity. [ABSTRACT FROM AUTHOR]

Approximately two thirds of migratory songbirds in eastern North America negotiate the Gulf of Mexico (GOM), where inclement weather coupled with no refueling or resting opportunities can be lethal. However, decisions made when navigating such features and their consequences remain largely unknown due to technological limitations of tracking small animals over large areas. We used automated radio telemetry to track three songbird species (Red-eyed Vireo, Swainson's Thrush, Wood Thrush) from coastal Alabama to the northern Yucatan Peninsula (YP) during fall migration. Detecting songbirds after crossing ~1,000 km of open water allowed us to examine intrinsic (age, wing length, fat) and extrinsic (weather, date) variables shaping departure decisions, arrival at the YP, and crossing times. Large fat reserves and low humidity, indicative of beneficial synoptic weather patterns, favored southward departure across the Gulf. Individuals detected in the YP departed with large fat reserves and later in the fall with profitable winds, and flight durations (mean = 22.4 h) were positively related to wind profit. Age was not related to departure behavior, arrival, or travel time. However, vireos negotiated the GOM differently than thrushes, including different departure decisions, lower probability of detection in the YP, and longer crossing times. Defense of winter territories by thrushes but not vireos and species-specific foraging habits may explain the divergent migratory behaviors. Fat reserves appear extremely important to departure decisions and arrival in the YP. As habitat along the GOM is degraded, birds may be limited in their ability to acquire fat to cross the Gulf. [ABSTRACT FROM AUTHOR]

Radiotelemetry has advanced the field of wildlife biology, especially with the miniaturization of radio-tags. However, the major limitation when radio-tagging birds is the size of the animal to which a radio-tag can be attached. We tested how miniature radio-tags affected flight performance and behavior of Ruby-throated Hummingbirds (Archilochus colubris), possibly the smallest bird species that has been fitted with radio-tags. Using eyelash adhesive, we fitted hatch-year individuals (n = 20 males, n = 15 females) with faux radio-tags of 3 sizes that varied in mass and antenna length (220 mg, 12.7 cm; 240 mg, 12.7 cm; and 220 mg, 6.35 cm), then filmed the birds in a field aviary to quantify activity budgets. We also estimated flight range using flight simulation models. When the 3 radio-tag packages were pooled for analysis, the presence of a radio-tag significantly decreased both flight time (∼8%) and modeled flight range (∼23%) in comparison to control birds. However, a multiple-comparison analysis between the different packages revealed that there was a significant difference in flight time when the larger radio-tag package (240 mg) was attached, and no significant difference in flight time when the lighter radio-tag packages (220 mg) were attached. Our results are similar to those of other studies that analyzed the flight time or flight range of birds wearing radio-tags. Therefore, currently available lightweight radio-tags (⩽220 mg) may be a new option to aid in the study of hummingbird biology. Future study should focus on the additional drag created by the radio-tag and the effects of the lightest radio-tag packages on free-ranging birds. These studies would provide additional information to determine the feasibility of the use of radio-tags to study hummingbird biology. [ABSTRACT FROM AUTHOR]

Predation is not thought to contribute significantly to adult hummingbird mortality in temperate areas, where most reported cases of mortality are the result of accidents (e.g., window collisions and spider webs). However, the hazards encountered during migration, including the threat of predation, can impact hummingbirds while on stopover. We present one account of predation upon Archilochus colubris (Ruby-throated Hummingbird) by Accipiter striatus (Sharp-shinned Hawk) and one account of a Ruby-throated Hummingbird displaying anti-predator behavior by mobbing a Falco sparverius (American Kestrel). All observations took place in coastal Alabama during stopover in autumn. [ABSTRACT FROM AUTHOR]