MAPPING THE BLACK-CROWNED NIGHT HERON: Uncovering the colony dynamics and hidden movements of North America’s stealthiest wading bird

Research Advisor: Dr. Michael P. Ward 

ZOOM LINK: https://go.illinois.edu/SarahSlayton 

Despite being the most widely distributed colonial wading bird in the world, Black-crowned Night Herons (Nycticorax nycticorax; BCNH) face substantial population declines and have been listed as a special-status species in 11 states. Amidst widespread loss or conversion of their preferred wetland habitat, this species has shown remarkable flexibility in its breeding habitat selection, nesting in a variety of natural and anthropogenic landscapes. In Illinois, the last major BCNH rookery in the state is located at the Lincoln Park Zoo near downtown Chicago. Although nesting in an urban center is inherently risky, this colony appears to be thriving. However, little research has been conducted on how these birds acquire resources and utilize city habitats to cope with the environmental pressures posed by urban living. To better understand patterns in their colony site preferences, I conducted a nationwide review of historical and extant BCNH colonies to explore trends in their geographical, physical, and biological characteristics. While BCNH were recorded nesting in nearly every U.S. state, in over 50 species of vegetation, and with over 30 different species of colonial wading or waterbirds, there are clear patterns in their colony composition.  I also studied the movements of individual birds during the breeding season in Chicago using GPS/GSM satellite transmitters. These trackers have shown that BCNH forage in a wide variety of natural and highly modified waterbodies, and revealed unexpected patterns in behavior between actively breeding and non-breeding birds in terms of their home range size, habitat selection, and activity patterns. This investigation of both fine scale and broader trends in BCNH habitat requirements during the breeding season will inform conservation efforts for this species in Illinois and beyond.

This institution is an equal opportunity provider.

Temporal changes in forest structure, composition, and carbon storage at Trelease Woods

Research Advisors: Drs. Jennifer Fraterrigo and Jim Dalling

Zoom link: https://go.nres.illinois.edu/AlvarezDefense (pw trelease)

Temperate deciduous forests in the eastern U.S. are undergoing significant changes driven by both biological and human-induced factors, such as fire suppression and invasive species. Understanding the structural and compositional shifts in these forests is essential to assess their long-term sustainability. To explore these changes, I analyzed nearly a century of historical data from an old-growth forest remnant in Urbana, Illinois, focusing on the structural, compositional, and carbon (C) storage changes. My findings show a decline in species richness and diversity, with an increase in sugar maple dominance and the rapid decline of elm and ash species due to biotic invasions. Despite these disturbances, the forest maintained its aboveground C storage. These changes reflect broader trends of mesophication in eastern forests, where fire suppression – along with invasive species – have contributed to species homogenization. Overall, my results indicate that Trelease Woods has managed to sustain aboveground C stocks despite a loss of species diversity and increased homogenization.

IS TIMING EVERYTHING? Examining the importance of parasitism timing to cowbird chick success

Research Advisors: Dr. Jeff Hoover and Dr. Wendy Schelsky

Zoom link: https://go.illinois.edu/DefenseZoomLink

Brood parasitism, a reproductive strategy where a parasitic parent leaves its offspring to be raised by an unrelated host, has resulted in specialized adaptive behaviors on the part of the parasite. The parasite must decide when to parasitize a host, and erring in this decision could have dire fitness consequences, thus resulting in strong selection for specific parasitism timing behaviors. Brown-headed cowbirds are North America’s most widespread avian brood parasite and successfully parasitize 170+ host species, but female cowbirds are cryptic and difficult to monitor, and much of how they make parasitism decisions is not well understood. Despite such diversity in hosts, cowbirds nearly always parasitize during the narrow window of the host’s laying period before the start of incubation, resulting in their offspring hatching before the host’s. How important is this timing to get right, and what are the reproductive costs to parasitizing - and thus hatching - late? I simulated three different parasite timing decisions by adding cowbird eggs to the nests of a common host, the prothonotary warbler, at different stages of the host’s laying and incubation period and monitored the effects on cowbird chick success. I found that late parasitism significantly reduced cowbird chick survival, suggesting that accurate parasitism timing is an essential and potentially strongly selected for behavior.

This institution is an equal opportunity provider.

A comprehensive evaluation of indicator species of high floristic quality wetlands 

Advisors: Dr. Suneeti Jog and Dr. Jason Bried

Zoom link: https://go.illinois.edu/FinzelDefense

Floristic Quality Assessment (FQA) is a popular bioassessment tool, especially in North American wetland ecosystems. The main components of FQA are native species richness and conservatism, the concept that native plant species have varying levels of fidelity to undegraded environmental conditions. FQA generally assumes that entire plant assemblages have been representatively sampled and identified to the species level; this assumption requires a significant level of field botany and taxonomic expertise. Recent findings, however, suggest that FQA metrics [Floristic Quality Index (FQI) and Mean Coefficient of Conservatism (Mean C)] do not require full taxonomic coverage, enabling FQA across a wider range of applications and end users and motivating the evaluation of taxonomic surrogates. Quantitatively validated indicator species, singly or in small combinations, have become a popular option for surrogacy. Building on this realization, I tested indicator species for high floristic quality using a variety of performance criteria and comparing them to other popular floristic quality taxonomic surrogates: dominant species and familiar species. Using two large Illinois wetland datasets, indicator species for high floristic quality (“high” meaning the upper quartile for FQI and Mean C) were identified using a resampling approach to Indicator Value analysis, and then evaluated based on the indicators’ performance, validity, and robustness. Some high-performing candidate indicator species for Mean C, such as Eutrochium maculatum, outperformed dominant species in accurately predicting high floristic quality sites. These data suggest that indicator species can yield reliable floristic quality estimates; however, their breadth is variable when compared to other surrogacy methods. Indicator species performed on-par with dominant species in most cases but failed to compete with the information provided by familiar species. Overall, except for a few indicator species of high Mean C, these findings support the long-standing notion that further ecological information can be gleaned when more species are included in an assessment.  

This institution is an equal opportunity provider.

ON THE ROAD AGAIN: Utilizing native plants in lieu of exotic cool season grasses on roadside rights-of-way

Research Advisors: Dr. Jeffrey Matthews and Dr. Rabin Bhattarai

Zoom link: https://tinyurl.com/bptm3p76 

To provide evidence-based revisions to the IDOT and InDOT roadside specifications manuals, I reviewed native species usage in roadside manuals of midwestern DOTs, finding many different approaches to native seeding and making recommendations for improvements based on best-practices. I also assessed native mixes competetiveness with existing IDOT mixes in cover and richness experiments, finding differences by mix but overall positive effects of native mixes. I surveyed native plantings along roadsides in IN and IL, evaluated variables to determine which factors led to long-term establishment, and found cover by seeded native species and native species overall increased with distance from road and decreased with increasing soil N and P. I found that number of native and seeded native species increased with distance from road and greater mix diversity. 28 species were observed at more than half of their seeded sites. Our results suggest that native plantings can persist on roadsides for several years after planting, but that specific site-level factors increase the likelihood of long-term success.

This institution is an equal opportunity provider.

AGROFORESTRY ADOPTION IN ILLINOIS: Influence of Place Attachment and Development of an Agroforestry Suitability Tool

Research Advisor: Dr. Chloe Wardroopper

Zoom link: https://go.nres.illinois.edu/RamirezDefense 

The Midwest has seen an increase in climate-smart agriculture practices that aim to combat environmental degradation from conventional agriculture. One of these practices is agroforestry, the intentional integration of woody perennials into agriculture, which has the potential to improve soil health, sequester carbon, and increase biodiversity. Adoption of agroforestry varies due to technical, financial, and structural challenges; thus, research is needed to better understand—and assist—farm operators deciding to adopt this intensive practice. I conducted semi-structured interviews (n=36) with agricultural stakeholders across Illinois. I find retired individuals and young operators are adopting agroforestry because of their place attachment to their farm. These operators are adopting agroforestry because it contributes to their quality-of-life goals for their families, community, and farms biodiversity. Additionally, I present the development process of the Agroforestry Suitability Tool, an online geospatial decision-support system that aims to assist program administrators targeting suitable areas for agroforestry adoption across the Midwest. 

This institution is an equal opportunity provider.

The Technology Services No Change period is designed to minimize the number of technical disruptions that might occur around final exams.

Beginning on Reading Day and continuing a few days past the end of finals, Technology Services tries to make no technical changes to hardware or software that might disrupt the availability of the campus network, data storage, web sites or any of the software-based services that Technology Services provides to campus. Changes or updates will only be made by Technology Services for emergency purposes during the No Change period.