Doing It Again: Repeating Methodology from Published Literature to Learn Field Biology

Repeatability underpins a basic assumption in science which students must learn in order to evaluate others’ research findings as well as to communicate the results of their own research. By attempting to repeat the methods of published studies, students learn the importance of clear written communication, while at the same time developing research skills. I describe three examples of published field studies that can be used as the basis for course exercises on the repeatability of methodology, as well as field sampling techniques, all grounded in the overall topic of environmental change. Two of the exercises returned students to the exact location of the past research that they had previously read from the primary literature, making it possible to clarify the difference between reproducibility and repeatability in field-based research. When student-collected data differed from published results, students explored, through both post-project discussions and written work, factors that could explain this variation, including methodology, ecological succession, and climate change. Assessments and student comments on course evaluations showed that these exercises have a positive impact on students’ communication skills and engagement with the scientific process

National Park Service nonnative plant control in the Indiana Dunes National Lakeshore

Invasive plants have become a growing threat to plant diversity and hydrology in the Indiana Dunes National Lakeshore. Invasive plants compete with native plants for nutrients and sunlight, and certain invasive species have been known to completely take over certain areas of wetlands, nearly destroying entire ecosystems. The Dunes Lakeshore contains over 1,400 plants species and is one of the top ten most diverse national parks in the United States. The mission statement of the National Park Service is to “preserve for the educational, inspirational, and recreational use of the public certain portions of the Indiana Dunes.” In order to properly maintain this unique habitat for future generations, a variety of techniques have been implemented to reduce the growth and germination of many nonnative plants in high quality areas such as Cowles Bog, West Beach, and Tolleston Dunes. We focused on depleting the seed bank of invasive plants by targeting certain species such as garlic mustard, Dame’s Rocket, and Crown Vetch before they seeded. Backpack sprayers, brush cutters and loppers were used to kill invasive plants within the park and GPS was used to monitor our progress

Does Branch Structure of an Invasive Shrub (Elaeagnus umbellata) Alter Bird Perching Behavior?

Autumn Olive, Elaeagnus umbellata, has been introduced throughout the United States. Research on the impacts of invasive plants like E. umbellata on bird behavior has produced conflicting results with some birds preferring to use invasives while others avoid them. Branch structure has been implicated in bird preference for certain woody species. Thus, we asked the question, does E. umbellata differ in branch structure from common natives in the landscape and, if so, how does this difference impact the behavior of native birds? We examined this question during the non-fruiting season at study sites with mixed open and shrubby second growth forest habitats in Michigan and Indiana. We found that E. umbellata branches were twice as dense and 45% smaller in diameter than those of native cherry, Prunus serotina, but did not differ from two other native shrubs. Birds did not show a preference for perching in native shrub branches in choice tests using bird feeders in situ with invasive or native branches. Mist net capture rates for birds also did not differ between E. umbellata and native shrub sites. We concluded that native birds do not avoid E. umbellata during the non-fruiting season for perching despite a unique branch structure

The effect of polypropylene on the formation of byssal threads produced by Dreissena polymorpha (zebra mussels)

The presence of microfibers and microplastics in the environment is an ever-growing ecological concern. Accumulation of microplastics (plastic particles smaller than 5 mm) in aquatic environments and the subsequent exposure of these particles to organisms have been shown to have negative effects on aquatic biota. As an invasive, filter-feeding bivalve found across Indiana freshwater ecosystems, the zebra mussel (Dreissena polymorpha) serves as a good model organism for studying microplastics’ effects on physiological and behavioral functions of affected organisms. We have studied the impacts of microplastic exposure on a freshwater mollusk, the zebra mussel. We collected zebra mussels from Stone Lake, Indiana, in late fall of 2019. Individual zebra mussels were exposed to polypropylene rope fibers (concentration of rope fibers in the environment of one zebra mussel was ~400 microfibers per L) for 24-hour trials and assessed the effects by production of byssal threads, which are produced by the zebra mussel for anchorage and in response to predation threats. Results from a comparison between unexposed control mussels (n=70) and mussels exposed to rope fibers (n=70) revealed no significant difference in motility nor the number of byssal threads produced. Despite using microplastic concentrations that were higher than that found in the Great Lakes, a 24 hour exposure time may still not have been enough to significantly impact the animals. Continued research on the attachment strength of Dreissena polymorpha exposed to rope fibers will provide clearer evidence of any direct effect of these microplastics on the ecologically important mussel species

Use of Plastic Nesting Material and its Potential Impact on American Robin (Turdus migratorius) Nests

Rising levels of plastic pollution in the environment continue to impact aquatic and terrestrial organisms, including birds when they incorporate it into their nests. Whether the use of plastic as nesting material is entirely helpful or harmful is largely unknown. Potential detrimental effects of incorporating non-anthropogenic matter as nesting material include entanglement, ingestion, alteration of thermal properties, and increase in predation risk. The proportion of plastic used in robin (Turdus migratorius) nests was determined in 3 types of locations in Northwest Indiana. These sites included shopping area parking lots, Valparaiso University campus, and local parks. Post-breeding season robin nests (n=44, f=4.51, p\u3c.025) were collected and dissected. Overall, 89% of the nests contained plastic. The nests with the most plastic originated from shopping areas. The effects plastic material had on nest predation rate were examined by placing artificial and natural nests around campus with model clay eggs. Half of the trials had white polyethylene plastic incorporated into their nests, and half contained no plastic. Time to nest disturbance or the presence of animal markings on the eggs were used to measure predation. In 2022, 74% of the nests were attacked with more predation from bird species than mammals. The time until predation was significantly longer for nests with plastic (n=11, t=2.3, p\u3c.050). In 2023, the experiment was replicated, and results indicated that the time until predation was significantly longer for nests without plastic. Future research is required to understand the comprehensive impacts plastic has on bird nest quality and breeding success

Bird dispersal of native and non-native plants in a Northwest Indiana nature preserve

Non-native plant species have gained much attention in recent years because they often compete with native plants and overtake landscapes. Birds act as vectors to disperse non-native seeds, which might perpetuate the spreading of non-native plant species. In this study, we tested the dispersal rates of native and non-native fruiting plant species by small perching birds at a nature preserve in Northwest Indiana. To conduct this study, we collected fecal material weekly from fecal traps set in meadow landscapes near forested areas. The material was then analyzed by counting seeds and seed numbers were compared to what was available in the landscape from fruit surveys conducted in mid-October and late November. We collected over 482 fecal samples from 16 traps from early September to mid-December. 888 seeds were collected and 98% of these seeds were identified to species. Early in the fall season (Oct), strong preference was shown for native fruiting species compared to what was available for consumption, especially for Parthenocissus quinquifolia. Late in the season (Nov), a preference was still shown for native fruits, but the preference was not as strong. This research has implications for managing the spread of invasive species

Species comparison of the physical properties of loblolly and slash pine wood and bark

Composition of the southern pine forest is now predominated by two species, loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.), owing to fire suppression activities, natural regeneration on abandoned agricultural lands, and extensive planting. Comparisons of the wood and bark physical properties of these pines is of interest in terms of the yields of usable biomass, and for the bark, its ecological functionality on a living tree. Trees from a species comparison study were used to generate wood and bark property data, on a whole-tree basis, and for stem disks collected at breast height. Models were constructed to explain the effect of relative height on wood and bark properties. When comparing the whole-tree data, slash pine wood (0.523 vs. 0.498) and bark (0.368 vs. 0.311) specific gravity values were higher, both offset by lower moisture contents; slash pine, also produced a higher percentage of bark on a dry-mass basis (17% vs. 12.5%). Unlike wood properties, bark properties showed significant between-species differences when determined at breast height alone, the exception being moisture content. In terms of yield, harvests of a green tonne of loblolly pine and slash pine would give approximately the same dry weight of wood, but slash pine provides more bark.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Branch Morphology of Nonnative Elaeagnus Shrubs and Potential Consequences for Avian Activity in Midwestern Habitats

Invasive nonnative species of woody plants can alter landscapes in ways that are detrimental to native wildlife. We studied branch structure of invasive nonnative Elaeagnus shrubs (autumn and Russian olive E. umbellata and E. angustifolia) as a potential influence on native bird activity in Midwestern habitats. In a comparison to three common native woody plants, Elaeagnus shrubs had a finer branch and denser structure than native black cherry (Prunus serotina) but did not differ from natives in other characteristics tested. Further, the morphological characteristics of Elaeagnusbranches did not appear to affect preference for perching substrate at feeders or activity of birds moving through Elaeagnus and native shrub areas monitored using mist nets. Thus, we concluded that any morphological changes that may occur when Elaeagnus shrubs invade a habitat would not negatively impact overwintering and breeding bird perching behavior or movements during the nonfruiting season