Omnidirectional bioacoustic recording systems offer the ability to record forest songbirds in the field by technical staff, and then interpret the recordings later in the laboratory by skilled interpreters. Among several advantages to this approach are the ability to estimate variance among interpreters, obtain a permanent archival record of the point count, reduce costs by using regular field crews to collect data vs. those skilled in bird identification, and remove impediments to breeding bird surveys due to lack of available skilled birders. In this study we first evaluated the effects of microphone configuration and digital processing methods on the quality and effectiveness of the recordings, and then evaluated how consistently skilled birders interpreted the same songbird recordings collected under a mix of environmental conditions, and related this to the commonness of the species. At the time of this evaluation, the most cost-effective configuration of the bioacoustic monitoring system included use of a 180°/180° microphone combination, a minidisc digital recording system, analog transfer of the sound data via a digital soundcard, post-processing amplification of the signal, and data storage in an .MP3 format. This combination maintains high sound fidelity while minimizing both expense and data storage requirements. As recording device technology improves, the direct storage and digital transfer of .WAV format files will be the preferred and most effective recording option. Despite noisy conditions due to wind and other ambient sounds for many of the recordings, interpreters showed a high level of similarity in species identification and enumeration for the 34 most abundant species. Standardized coefficient of variance increased sharply when species had fewer than 10 occurrences, suggesting that birders are more variable in their identification of rare or uncommon species. Desktop identification systems that include type specimens of spectrographic signature and sound clips to aid interpreters could improve identification accuracy of rarer species.

Knowledge of chick survival rates is required to develop species-specific habitat-survival relationships. We determined pre-flight daily survival of Rio Grande Wild Turkey (Meleagris gallopavo intermedia) chicks from hatching to time of tree roost at four sites in southwestern Kansas and the Texas Rolling Plains, May–August, 2000 and 2001. One-hundred twenty-three chicks from 39 broods were equipped with cyanoacrylate-attached transmitters. The first day of brood tree-roost ranged from 9–16 d after hatching. Chick survival to 16 d of age ranged from 0.11 to 0.67. One-hundred percent of mortalities in 2000 and 70% of mortalities in 2001 for chicks 0–16 d old occurred <10 d after hatching. Survival at two of four sites was higher for 10–16 d-old chicks than 0–9 d-old chicks. Combining different survival periods may cause biased results when examining habitat-survival relationships.

Traditional methods of examining the nest contents of burrow-nesting birds have often been destructive, expensive, and/or limited to large-bodied species. Here we present details of a small, efficient, and inexpensive “burrowscope” designed for examining the nest tunnels of very small birds. The burrowscope consists of a tiny (16 mm × 22 mm) video camera and infrared light-emitting diodes, mounted on the end of flexible conduit (20-mm diameter) that houses a live video feed to a small, hand-held monitor display. In total, the burrowscope is only 22 mm wide at its widest point, weighs approximately 900 g, and was built for less than US $400. The burrowscope was tested in the field and could be used at 99.8% of Rainbow Bee-eater (Merops ornatus) nests and 100% of Spotted Pardalote (Pardalotus punctatus) nests (one of the world's smallest burrow-nesting birds). The accuracy of the burrowscope was evaluated by excavating a nest access hole at a sub-sample of Rainbow Bee-eater nests. The burrowscope enabled precise determination of clutch size at 30 of 30 nests, and brood size at 125 of 127 nests. The equipment could be applied to other organisms, including some invertebrates, reptiles, amphibians, and burrow-nesting mammals.

Each autumn, American Crows (Corvus brachyrhynchos) in the Central Valley of California, USA, forage heavily on walnut trees (Juglans regia) planted along residential streets. Some of these nuts are dropped onto roads and cracked for immediate consumption, but others are carried away from foraging sites to be cached. I quantified caching behavior to understand its importance in corvid natural history and the potential for corvids to disperse large tree seeds. Crows cached an estimated 2000 walnuts/km²/yr in agricultural fields 1–2 km away. Most (73%) crows that found a walnut left the foraging site with it, and most (77%) of these crows cached their nuts. Some crows carried walnuts long distances (e.g., 5% of nuts foraged from trees were carried >2 km) and buried them in unforested habitat; this indicates that crows may be agents of tree seed dispersal. Transporting and caching a nut required approximately 10 min and increased the likelihood of it being stolen, relative to a nut eaten immediately at the walnut tree. Without knowing the timing and rates of recovery, it is unclear when and to what degree American Crows benefit from walnut-caching, which has not been previously described in this species.

The Long-billed Curlew (Numenius americanus), a declining species of Nearctic shorebird, winters as far north as Humboldt Bay, California, where it feeds principally in intertidal habitats but shifts to pastures with onset of seasonal rains. We studied variation in abundance and behavior of curlews in coastal pastures in relation to environmental variation that may influence the profitability of intertidal and pasture habitats as foraging sites. Curlews occurred in greater abundance in pastures during morning hours, when intertidal habitats were exposed for longer intervals during daylight hours, and coincident with greater rainfall. While using pastures, most curlews fed, and this proportion varied positively with intervals of lower tides in intertidal habitats. Pastures provide important foraging habitat for approximately one third of the 200–300 curlews wintering at Humboldt Bay, especially when inclement weather makes foraging in intertidal habitats difficult and increases food availability in pastures.

We compared direct observation methods to assess the diet of nestling Bearded Vultures in the Pyrenees northeastern Spain. Using video cameras and telescopes, diet was determined from observations of food items delivered to, and prey remains in, nests. Using video cameras, the proportion of prey identified in remains in nests was significantly greater than that identified using telescopes, but no differences were found in food items delivered to the nest and in the species composition of the diet. Data suggest that the proportion of prey identified in food items delivered was greater than that identified in prey remains. Prey remains and food items delivered grouped by taxa showed significant differences, with the remains underrepresenting small prey. By combining data on prey remains and food items delivered, these biases can be reduced or eliminated. The results suggest that the combination of prey remains and food items delivered allow one to increase sample size without biases and thus to optimize the considerable investment in time that this method of direct observation involves.

We present an efficient and effective method for trapping adult, breeding American Oystercatchers (Haematopus palliatus) that minimizes disturbance to nesting birds and the risk of trapping injuries. We used a remote controlled mechanical decoy to lure territorial adults to a leg-hold noose-mat trap. We trapped 25 birds over two seasons and were successful on 54% of our trapping attempts in 2003. We only trapped birds before the breeding season or between nesting attempts to reduce nest-site disturbance.

We compared transect counts used for the annual official count of male Kirtland's Warblers (Dendroica kirtlandii) to an observation-based mapping method of individually sighted males in 155 stands over 10 yrs. The annual census count almost tripled from 1990 to 1999. The transect and observation-based mapping method showed the same increasing trend in population between 1990 and 1999, except from 1992 to 1993. The annual official census transect count was consistently higher than the mapping method for stands censused in common. After standardizing for sample size, the annual number of Kirtland's Warblers per stand increased through time with the transect method, while there was a positive, non-significant trend with the mapping method. After 1992, the two methods began diverging in the number of males per stand. The relationship between the differences in count between methods (mapping count minus transect count) to the official transect count varied among years. At the stand level, the transect-method count was greater than the mapping count in 60% of the stands, while the mapping count was greater than the transect count in 16.3% of the stands. The difference in count between methods at the stand level ranged from −43 to 10. We illustrate the difficulties with interpreting transect counts due to Kirtland's Warblers' large territory sizes, occasional double territories, and active territorial defense during early morning hours. We suggest improvements to help correct these sources of error. We conclude that the official census transect counts are a satisfactory relative index, but results should not be interpreted as an absolute count.

Little is known about the breeding biology of the Le Conte's Sparrow (Ammodramus leconteii), probably because of its secretive nature. We provide new information on several aspects of Le Conte's Sparrow breeding biology, including rates of nest parasitism by Brown-headed Cowbirds (Molothrus ater) and potential factors affecting breeding densities and nesting success of the species. Our study was conducted in the tallgrass prairie of northwestern Minnesota and southeastern North Dakota during 1998–2002. Breeding densities varied among years, but this variation was not clearly linked to climatic patterns. Vegetation had some influence on densities of Le Conte's Sparrows; densities were highest in grasslands with moderate amounts of bare ground. Prairie patch size and the percentage of shrubs and trees in the landscape had no recognizable influence on density. Nesting success was highly variable among sites and years and increased slightly with distance from trees. Rates of nest parasitism were low (1 of 50 nests parasitized), and clutch sizes were similar to those of other studies of Le Conte's Sparrows.

We studied short-term responses by 16 species of breeding landbirds to group-selection timber harvest at four 21.2-ha replicated study stands in montane hardwood-conifer habitat in the central Sierra Nevada Mountains, California, 1995–2002. The group-selection timber harvest was done to enhance stand conditions for California black oak (Quercus kelloggii), the dominant hardwood. Birds were censused using point counts, and harvesting effects were assessed using the Before-After/Control-Impact Pairs (BACIP) design where the response variables were the differences in landbird abundances between paired treatment and control plots for pre- and post-treatment periods. Each stand had paired and adjacent 10.6-ha treatment and control plots, and four 0.6-ha group-selection units were randomly placed and harvested in each treatment plot in 1998 and 1999. In the treatment plots, tree basal areas and tree densities were reduced approximately 30% and snag densities were reduced approximately 45% with the harvest. Abundance differences between pre- and post-treatment periods differed among stands for 11 (69%) species. Significant differences in abundance between the pre- and post-treatment periods were found for Steller's Jays (Cyanocitta stelleri), Warbling Vireos (Vireo gilvus), and Western Wood-Pewees (Contopus sordidulus). Significant interactions between stands and treatment periods were found for Evening Grosbeaks (Coccothraustes vespertinus) and Western Wood-Pewees, indicating that responses differed among stands. Significant differences between treatment periods were due to proportionately greater decreases in post-treatment period abundance in control plots than in treatment plots (Evening Grosbeak, Steller's Jay, Warbling Vireo) or a proportionately lesser increase in post-treatment period abundance in the control plots than in treatment plots (Western Wood-Pewee). We conclude that group-selection harvesting had neutral or positive short-term effects on the species studied.

Adult Rough-legged Hawks (Buteo lagopus) are depicted and described in bird guides and handbooks as sexually dimorphic in plumage. We describe for the first time a Basic II plumage for this species, determined by incomplete flight feather molt, in which both sexes have the characters of adult females, and Basic III plumages that are essentially adult by sex but show pale primary patches on the upper wings.

The Piapiac, a little-known corvid, may be the African counterpart of the American jays, and its behavior supports a hypothesized link between conspicuous bill coloration of juveniles and sociality of the species. During field observations in Cameroon, juvenile Piapiacs in mixed groups displayed their brightly pink bills by gaping at adults as though begging for food but often when no food could be obtained. They were more aggressive and vocal than adults against presumed enemies, and situations that aroused the group seemed to elicit gaping. The conspicuous bill coloration of juvenile Piapiacs matches their conspicuous behavior in mixed groups, and may act as a persisting infant signal, useful to block aggressive reactions by adults and facilitate acceptance of juveniles as helpers.

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.