An East-West Comparison of Migration in North American Wood Warblers

That western and eastern songbird migration routes are distinct ecological systems has been proposed for over 100 years. Nonetheless, this distinction has not been widely recognized nor have there been any comparative studies that quantitatively evaluate the differences and similarities between western and eastern songbird migration systems. We drew from previously published research on wood warblers to highlight patterns in stopover ecology that suggest fundamental differences between western and eastern migrants. In particular, we compared biogeography, evolutionary relationships, and stopover ecology of wood warblers from western and eastern North America and found: (1) multiple lines of evidence that indicate western wood warblers are geographically isolated from eastern con-specifics or congeners throughout the annual cycle, (2) eastern and western wood warbler taxa are distinct evolutionary units, (3) migrant wood warblers captured in the Southwest tended to carry lower fat loads and be comprised of more after-hatch-year birds than is typical of eastern migrants, (4) frugivory is unknown in wood warblers endemic to the Northwest or Southwest and (5) relative to other regions and seasons, riparian vegetation is heavily used by western wood warblers in the spring. We think that further examination and synthesis of these differences would yield a more mechanistic understanding of Nearctic-Neotropical avian migration. On this basis, we elaborate our view that (1) an improved understanding of western songbird migration ought to be a high priority for science, conservation, and education, and (2) large-scale coordinated research efforts would be the most effective strategy for advancing our knowledge of passerine migration in the West. /// Por más de 100 años se ha propuesto que las rutas de migración de aves paseriformes del este y del oeste son sistemas ecológicos diferentes. Sin embargo, esta distinción no ha sido reconocida ampliamente, ni se han realizado estudios comparativos que evalúen cuantitativamente las diferencias y similitudes entre los sistemas de migración del este y del oeste. Revisamos estudios previamente publicados sobre aves de bosque de la familia Parulidae (Reinitas) para destacar los patrones ecológicos de las paradas migratorias que sugieran diferencias fundamentals entre las aves paseriformes migratorias el este y del oeste. Particularmente, comparamos la biogeografía, las relaciones evolutivas y la ecología de las paradas migratorias de las Reinitas del este y del oeste de Norteamérica y encontramos: (1) múltiples líneas de evidencia que indican que las Reinitas del oeste se encuentran geográficamente aisladas de sus coespecíficos o cogenéricos del este durante todo el ciclo anual, (2) los taxa del este y del oeste son unidades evolutivas independientes, (3) las Reinitas migratorias capturadas en el suroeste tendieron a presentar menores cargas de grasa y una mayor proporción de aves eclosionadas durante el año, que lo es típicamente observado para las aves migratorias del este, (4) la frugivoría no se conoce en las Reinitas endémicas del noroeste o sudoeste y (5) en relación a otras regiones o estaciones, la vegetación riparia es usada intensamente durante la primavera por las Reinitas del oeste. Creemos que estudios adicionales y una síntesis de estas diferencias podrían producir un mejor entendimiento mecaní stico de la migración Neártico-Neotropical de aves. Basados en esto, sugerimos que (1) un mejor entendimiento de la migración de aves paserinas del oeste debería tener alta prioridad para la ciencia, conservación y educación y (2) que los esfuerzos de investigación coordinados a gran escala serían la estrategia más efectiva para progresar en nuestro conocimiento sobre la migración de las aves paserinas en el oeste

Influence of Habitat Quality on the Population Decline of the Red-cockaded Woodpecker in the Mccurtain County Wilderness Area, Oklahoma

This thesis is composed of two manuscripts written for submission to the Auk. Each manuscript is complete as written and does not require additional support material. Chapter I is an introduction to the rest of the thesis. Chapter II is entitled "The influence of foraging habitat quality on the population decline of the Red-cockaded Woodpecker in Oklahoma." Chapter III is entitled "Habitat associations of active Red-cockaded Woodpecker cavity trees in Oklahoma."Zoolog

Carbon Stable Isotope Analysis of Bison Dentition

Understanding how bison behaved in the past can provide key insights for today\u27s managers, ecologists, and anthropologists. However, the direct application of both historic documentation and modern field observations may not provide the necessary insights for understanding bison behaviors in archeological and paleontological contexts. In order to develop a better understanding of possible behavior within these contexts, we have developed individual foraging histories for 22 Bison bison from the Glenrock Buffalo Jump assemblage of the Plains Late Prehistoric period in Wyoming and four Pleistocene B. priscus from the Ukraine. Incremental stable carbon isotopic values of dental enamel were used to determine foraging histories. The progressive development of enamel allows for samples to be selected that represent distinct periods of an individual\u27s life. Comparison of these dietary patterns among members of a herd can demonstrate foraging behaviors of cohorts and, in turn, the entire assemblage. Application of this high resolution paleodietary technique provides new information on bison behaviors in a paleontological and archaeological context

Using Bioenergetics and Radar-Derived Bird Abundance to Assess the Impact of a Blackbird Roost on Seasonal Sunflower Damage

Methods aimed at reducing avian damage to agricultural crops are routinely implemented in situations where efficacy can be assessed by quantifying blackbird (Icteridae) abundance relative to environmental variables and extrapolating to ensuing crop damage. Concomitantly, Weather Surveillance Radar (WSR) data may have potential to enhance crop damage mitigation through improved monitoring of nuisance wildlife populations. We used WSR to derive daily abundance estimates of blackbirds at a fall roost in North Dakota, USA from 2012 to 2019. We integrated these estimates with previously developed bioenergetics-economic models to estimate local sunflower (Helianthus annuus) damage. The greatest losses usually occurred during a brief period in October, when peak blackbird abundance coincided with large percentages (\u3e50%) of mature but unharvested sunflower fields. Most sunflower fields were harvested later than peak blackbird abundance (360,000–1,120,000 birds) and maximum daily damages ($900–$2,000 USD per day). This seasonal trend suggests advancing harvest time as a strategy to avoid the greatest losses in yield (up to $1,800 in savings at this 1 roost), which may be attainable by earlier planting of early-maturing crop varieties or crop desiccation

A Comparison of Bird Detection Rates Derived from On-Road versus Off-Road Point Counts in Northern Montana

We conducted a series of 275 paired (on- and off-road) point counts within 4 distinct vegetation cover types in northwestern Montana. Roadside counts generated a bird list that was essentially the same as the list generated from off-road counts within the same vegetation cover type. Species that were restricted to either on- or off-road counts were rare, suggesting that restricted occurrences were a consequence of small sample sizes and not a product of habitat differences surrounding on-versus off-road points. Nevertheless, there were significant differences in the mean number of individuals detected between on- and off-road points for a number of species. Some of these differences appear to be a product of habitat changes associated with the presence of roads, and those differences appear to be less pronounced on narrower roads. Therefore, we recommend that, if one wishes to extrapolate results from on- to off-road areas, care should be taken to select smaller, secondary or tertiary roads as transect routes

Influence of Summer Biogeography on Wood Warbler Stopover Abundance

We evaluated the effect of summer biogeography of migrant wood warblers (Parulidae) on their stopover abundance. To characterize abundance patterns, we used mistnet capture data from spring and fall migration in the Middle Rio Grande Valley, New Mexico, spring migration on the Gulf Coast of Louisiana, and fall migration on the Gulf Coast of Alabama. To describe the summer biogeography of 47 species of wood warblers, we used indices of their summer range size, their summer density, and distance between their summer ranges and our netting sites. Multiple linear regressions indicated that biogeographic indices explained 55% and 49% of variation in captures in the Middle Rio Grande Valley during spring and fall, respectively. On the Gulf Coast these regressions explained 25% of the variation during spring at the Louisiana site and 51% during fall at the Alabama site. Both summer range size and distance between the summer range and study sites explained significant portions of the variation in three of the four analyses. Interestingly, the importance of biogeographic factors was least evident among spring migrants along the Gulf Coast of Louisiana. The difference between this site and other sites may reflect differences between migrants arriving after a Gulf crossing and those migrating across continental land masses or possibly an increased importance of winter biogeography for migrants crossing the Gulf of Mexico in the spring. In general, these results indicate that abundance of migrant warblers at our netting sites in both the eastern and western United States during spring and fall migration were influenced by summer biogeography. Consequently, we suggest including biogeographic analyses in assessments of conservation priorities for local stopover sites

Temporal Migration Patterns Between Natal Locations of Ruby-Throated Hummingbirds (\u3ci\u3eArchilochus colubris\u3c/i\u3e) and Their Gulf Coast Stopover Site

Background Autumn latitudinal migrations generally exhibit one of two different temporal migration patterns: type 1 where southern populations migrate south before northern populations, or type 2 where northern populations overtake southern populations en route. The ruby-throated hummingbird (Archilochus colubris) is a species with an expansive breeding range, which allows opportunities to examine variation in the timing of migration. Our objective was to determine a relationship between natal origin of ruby-throated hummingbirds and arrival at a Gulf coast stopover site; and if so, what factors, such as differences in body size across the range as well as the cost of migration, might drive such a pattern. To carry out our objectives, we captured hummingbirds at a coastal stopover site during autumn migration, at which time we collected feathers from juveniles for analysis of hydrogen stable isotopes. Using the hydrogen stable isotope gradient of precipitation across North America and published hydrogen isotope values of feathers from populations of breeding ruby-throated hummingbirds, we assigned migrants to probable natal latitudes. Results Our results confirm that individuals from across the range (30–50° N) stopover along the Gulf of Mexico and there is a positive relationship between arrival day and latitude, suggesting a type 1 migration pattern. We also found no relationship between fuel load (proxy for migration cost) or fat-free body mass (proxy for body size) and natal latitude. Conclusions Our results, coupled with previous work on the spatial migration patterns of hummingbirds, show a type 1 chain migration pattern. While the mechanisms we tested do not seem to influence the evolution of migratory patterns, other factors such as resource availability may play a prominent role in the evolution of this migration system

Influence of coral and algal exudates on microbially mediated reef metabolism.

Benthic primary producers in tropical reef ecosystems can alter biogeochemical cycling and microbial processes in the surrounding seawater. In order to quantify these influences, we measured rates of photosynthesis, respiration, and dissolved organic carbon (DOC) exudate release by the dominant benthic primary producers (calcifying and non-calcifying macroalgae, turf-algae and corals) on reefs of Mo'orea French Polynesia. Subsequently, we examined planktonic and benthic microbial community response to these dissolved exudates by measuring bacterial growth rates and oxygen and DOC fluxes in dark and daylight incubation experiments. All benthic primary producers exuded significant quantities of DOC (roughly 10% of their daily fixed carbon) into the surrounding water over a diurnal cycle. The microbial community responses were dependent upon the source of the exudates and whether the inoculum of microbes included planktonic or planktonic plus benthic communities. The planktonic and benthic microbial communities in the unamended control treatments exhibited opposing influences on DO concentration where respiration dominated in treatments comprised solely of plankton and autotrophy dominated in treatments with benthic plus plankon microbial communities. Coral exudates (and associated inorganic nutrients) caused a shift towards a net autotrophic microbial metabolism by increasing the net production of oxygen by the benthic and decreasing the net consumption of oxygen by the planktonic microbial community. In contrast, the addition of algal exudates decreased the net primary production by the benthic communities and increased the net consumption of oxygen by the planktonic microbial community thereby resulting in a shift towards net heterotrophic community metabolism. When scaled up to the reef habitat, exudate-induced effects on microbial respiration did not outweigh the high oxygen production rates of benthic algae, such that reef areas dominated with benthic primary producers were always estimated to be net autotrophic. However, estimates of microbial consumption of DOC at the reef scale surpassed the DOC exudation rates suggesting net consumption of DOC at the reef-scale. In situ mesocosm experiments using custom-made benthic chambers placed over different types of benthic communities exhibited identical trends to those found in incubation experiments. Here we provide the first comprehensive dataset examining direct primary producer-induced, and indirect microbially mediated alterations of elemental cycling in both benthic and planktonic reef environments over diurnal cycles. Our results highlight the variability of the influence of different benthic primary producers on microbial metabolism in reef ecosystems and the potential implications for energy transfer to higher trophic levels during shifts from coral to algal dominance on reefs

Criminal Justice and Suicide Outcomes with Indiana's Risk-Based Gun Seizure Law

This article examines the application and effectiveness of a 2006 Indiana law designed to prevent gun violence by authorizing police officers to separate firearms from persons who present imminent or future risk of injury to self or others, or display a propensity for violent or emotionally unstable conduct. A court hearing is held to determine ongoing risk in these cases; a judge decides whether to return the seized firearms or retain them for up to five years. The study examines the frequency of criminal arrest as well as suicide outcomes for 395 gun-removal actions in Indiana. Fourteen individuals (3.5%) died from suicide, seven (1.8%) using a firearm. The study population's annualized suicide rate was about 31 times higher than that of the general adult population in Indiana, demonstrating that the law is being applied to a population genuinely at high risk. By extrapolating information on the case fatality rate for different methods of suicide, we calculated that one life was saved for every 10 gun-removal actions, similar to results of a previous study in Connecticut. Perspectives from key stakeholders are also presented along with implications for gun policy reform and implementation