Vertical foraging shifts in Hawaiian forest birds in response to invasive rat removal.

Worldwide, native species increasingly contend with the interacting stressors of habitat fragmentation and invasive species, yet their combined effects have rarely been examined. Direct negative effects of invasive omnivores are well documented, but the indirect effects of resource competition or those caused by predator avoidance are unknown. Here we isolated and examined the independent and interactive effects of invasive omnivorous Black rats (Rattus rattus) and forest fragment size on the interactions between avian predators and their arthropod prey. Our study examines whether invasive omnivores and ecosystem fragment size impact: 1) the vertical distribution of arthropod species composition and abundance, and 2) the vertical profile of foraging behaviors of five native and two non-native bird species found in our study system. We predicted that the reduced edge effects and greater structural complexity and canopy height of larger fragments would limit the total and proportional habitat space frequented by rats and thus limit their impact on both arthropod biomass and birds' foraging behavior. We experimentally removed invasive omnivorous Black rats across a 100-fold (0.1 to 12 ha) size gradient of forest fragments on Hawai'i Island, and paired foraging observations of forest passerines with arthropod sampling in the 16 rat-removed and 18 control fragments. Rat removal was associated with shifts in the vertical distribution of arthropod biomass, irrespective of fragment size. Bird foraging behavior mirrored this shift, and the impact of rat removal was greater for birds that primarily eat fruit and insects compared with those that consume nectar. Evidence from this model study system indicates that invasive rats indirectly alter the feeding behavior of native birds, and consequently impact multiple trophic levels. This study suggests that native species can modify their foraging behavior in response to invasive species removal and presumably arrival through behavioral plasticity.

Influence of plant community composition on biomass production in planted grasslands.

United States energy policy mandates increased use of renewable fuels. Restoring grasslands could contribute to a portion of this requirement through biomass harvest for bioenergy use. We investigated which plant community characteristics are associated with differences in biomass yield from a range of realistic native prairie plantings (n = 11; i.e., conservation planting, restoration, and wildlife cover). Our primary goal was to understand whether patterns in plant community composition and the Floristic Quality Index (FQI) were related to productivity as evidenced by dormant season biomass yield. FQI is an objective measure of how closely a plant community represents that of a pre-European settlement community. Our research was conducted in planted fields of native tallgrass prairie species, and provided a gradient in floristic quality index, species richness, species diversity, and species evenness in south-central Wisconsin during 2008 and 2009. We used a network of 15 randomly located 1 m2 plots within each field to characterize the plant community and estimate biomass yield by clipping the plots at the end of each growing season. While plant community composition and diversity varied significantly by planting type, biomass yield did not vary significantly among planting types (ANOVA; P >0.05). Biomass yield was positively correlated with plant community evenness, richness, C4 grass cover, and floristic quality index, but negatively correlated with plant species diversity in our multi-season multiple linear mixed effects models. Concordantly, plots with biomass yield in the lowest quartile (biomass yield < 3500 kh/ha) had 8% lower plant community evenness and 9% lower FQI scores than those in the upper quartile (biomass yield > 5800 kh/ha). Our results suggest that promoting the establishment of fields with high species evenness and floristic quality may increase biomass yield, while simultaneously supporting biodiversity.

Application of Conservation Biology Research to Management.

We conducted a survey of all primary authors of "Contributed Papers" and "Research Notes" in Conservation Biology from 1987 to 1998 to assess the perceived effectiveness of published management recommendations. No systematic survey has previously assessed the degree to which authors believe that resource managers are using the growing body of research published in Conservation Biology. In March 1999, we sent surveys to 667 authors of 790 published papers, asking whether their papers included management recommendations, whether such recommendations have been used in practice, and why they believed they have or have not been used. We received completed surveys from 198 authors of 223 papers. The percentage of papers that included management recommendations increased from 1987 to 1991, then stabilized at about 75%. Author perception of the use of management recommendations generally increased over the 5 years from 1994 to 1998. Initiatives of federal, state, and local agencies were the most often-cited cause of successful implementation of management recommendations, accounting for over half of all such cases. Our survey suggests that authors in Conservation Biology have increased the use of explicit management recommendations in their papers and that authors believe their recommendations are being used to an increasing degree.

RESUMEN: Llevamos a cabo un sondeo de todos los autores principales de "aportaciones en manuscritos" y "notas de investigación" de la revista Conservation Biology entre 1987 y 1998 para evaluar la efectividad percibida de las recomendaciones de manejo publicadas. Ningún sondeo sistemático previo ha evaluado el grado al cuál los autores creen que los manejadores de recursos están usando la creciente investigación publicada en Conservation Biology. En marzo de 1999, enviamos encuestas a 667 autores de 790 manuscritos publicados, preguntándoles si sus publicaciones incluyeron recomendaciones de manejo, si estas recomendaciones han sido puestas en práctica, y las razones por las cuales ellos creen que sus recomendaciones han sido o no han sido usadas. Recibimos las encuestas completadas de 198 autores de 223 manuscritos. El porcentaje de publicaciones que incluyeron recomendaciones de manejo incrementó entre 1987-1991, y posteriormente se estabilizó en aproximadamente un 75%. La percepción de los autores sobre el uso de las recomendaciones de manejo ha incrementado por lo general en los últimos cinco años (1994-1998). La iniciativa de las agencias federales, estatales y locales fue la causa más frecuentemente citada para la implementación exitosa de recomendaciones de manejo, abarcando más de la mitad de todos los casos. Nuestro sondeo sugiere que los autores de Conservation Biology han incrementado el uso de recomendaciones explícitas en sus publicaciones y que los autores creen que sus recomendaciones están siendo usadas cada vez más.

A comparative study of cadmium and copper in ruffed grouse (Bonasa umbellus) in regions with and without historic mining.

Mining activities can increase the bioavailability of metals in aquatic and terrestrial ecosystems. Following over 100 years of copper mining in portions of Michigan's Upper Peninsula (UP) terrestrial ecosystems retain vast quantities of waste rock with traces of cadmium and large concentrations of copper. We compared liver cadmium and copper concentrations in ruffed grouse (Bonasa umbellus), a popular game bird from landscapes with and without historic mining. We also used chickens (Gallus domesticus) to determine whether mine waste was a direct source of liver cadmium. Cadmium and copper levels did not differ between mining areas in Michigan and non-mining areas in Wisconsin. We found nearly significant difference between sexes in cadmium levels. Cadmium levels for all chickens were below the method detection limit of the lab (0.03 mg/kg) and copper levels did not differ in the experimental chickens. These results suggest that the historic mining in the western UP is not leading to higher cadmium or copper uptake in grouse.