About

Christopher J. Clark is the Director of Undergraduate Studies and an Associate Professor in the Department of Political Science at the University of North Carolina at Chapel Hill. He earned his B.A. from Saint Louis University in 2005, followed by an M.A. in 2006 and a Ph.D. in 2010 from the University of Iowa. His academic interests focus on racial and ethnic politics in the United States, with a particular emphasis on minority representation. His current work examines women of color political elites, both in Congress and state legislatures. Additionally, he is interested in political behavior and public opinion.

Research topics

• Computer Science
• Ecology
• Biology
• Acoustics
• Political Science
• Engineering
• Physics
• Aerospace engineering
• Oceanography
• Psychology
• Geology
• Zoology
• Communication
• Mechanics
• Art
• Law

Selected publications

• Estimating Wingbeat Frequency of Hummingbirds Using a No-Labeling Learning Computer Vision Approach

  Integrative and Comparative Biology · 2025-01-18 · 2 citations

  article

  Wingbeat frequency estimation is an important aspect for the study of avian flight, energetics, and behavioral patterns, among others. Hummingbirds, in particular, are ideal subjects to test a method for this estimation due to their fast wing motions and unique aerodynamics, which result from their ecological diversification, adaptation to high-altitude environments, and sexually selected displays. Traditionally, wingbeat frequency measurements have been done via "manual" image/sound processing. In this study, we present an automated method to detect, track, classify, and monitor hummingbirds in high-speed video footage, accurately estimating their wingbeat frequency using computer vision techniques and signal analysis. Our approach utilizes a zero-shot learning algorithm that eliminates the need for labeling during training. Results demonstrate that our method can produce automated wingbeat frequency estimations with minimal supervision, closely matching those performed by trained human observers. This comparison indicates that our method can, in some scenarios, achieve low or zero error compared to a human, making it a valuable tool for flight analysis. Automating video analysis can assist wingbeat frequency estimation by reducing processing time and, thus, lowering barriers to analyze biological data in fields such as aerodynamics, foraging behavior, and signaling.

  PublisherDOI

• Geographical variation in the songs of two closely related song-learning species, Anna's and Costa's hummingbird

  Animal Behaviour · 2025-06-24

  article
  PublisherDOI

• Flight performance during courtship in male black-chinned hummingbirds, Archilochus alexandri

  Animal Behaviour · 2025-10-29 · 1 citations

  articleSenior author
  PublisherDOI

• An Exploration of Condom Use Beliefs, Barriers, and Experiences among Blind and Low-vision Adults in the United States

  Sexuality and Disability · 2025-09-01

  articleOpen access

  Abstract Despite the importance of condom use for promoting sexual health and reducing unintended pregnancies and sexually transmitted infections (STIs), condom use experiences of blind and low-vision (BLV) adults have been largely unexplored. In the present study, 126 BLV adults participated in an online survey comprised of measures assessing condom use errors/problems, beliefs, and barriers, and two open-ended questions about their lived experiences related to condom use. Findings indicated that BLV adults share some commonalities with sighted individual in condom use errors and problems. However, unique barriers for BLV adults emerged, primarily lack of equitable access to condoms and comprehensive sexual health knowledge, underscoring the marginalization of this population in the United States. These results have significant implications for the sexual health of BLV adults. Recommendations for healthcare providers and educators include providing equitable access to condoms and information on sexual health and correct condom application.

  PublisherOA PDFDOI

• Measurement Errors Downstream of a Rotor due to Probe–Blade Row Interaction

  2025-06-16

  articleOpen access

  Abstract Pneumatic probes are widely used to measure flow properties in turbomachinery, including downstream of rotor blade rows. This paper investigates the aerodynamic interaction between a row of compressor blades and a downstream cylindrical probe, using unsteady, three-dimensional simulations. The study demonstrates the probe influence on rotor performance as a function of probe size and rotor proximity, identifies the physical mechanisms driving rotor-probe interactions, and quantifies the resulting probe measurement errors. A probe downstream of a rotor row causes each blade passage to deviate periodically from the steady, axi-symmetric characteristic, as they pass the probe. In this study, the largest rotor disturbance occurs for a probe of diameter 14% blade chord, located 30% axial chord downstream of the rotor trailing edges. The flow coefficient, ϕ, moving with the rotor passage, varies between −10.4% and +5.5% compared to a case with no downstream probe. The total-to-total pressure rise coefficient, ѱtt, increases by up to 7.7%. These rotor-probe interaction effects are driven by the unsteady response of the rotor passage to the potential field of the probe. In the stationary frame, measurement error occurs because the probe is exposed to the disturbed flow field and this leads to maximum average errors of Δϕ = −15.1% and Δѱtt = 8%. The magnitude of the rotor disturbance decreases as the probe is moved away from the trailing edge of the blades and when probe size is reduced. Reducing probe size close to the blade row reduces the rotor disturbance more than moving a large probe downstream. Including a stator blade row downstream of the probe does not have a large impact on the sensitivity to probe size and proximity and the physical mechanisms are unchanged.

  PublisherOA PDFDOI

• The Black Women of the US Congress: Learning from Descriptive Data

  UNC Libraries · 2025-04-29

  articleOpen access

  Black women have been historically excluded from Congress and the policymaking power available in the institution. This essay shares details about the 52 Black women who have navigated this raced and gendered institution (Hawkesworth 2003) since 1969. We discuss data on these Black congresswomen, including, but not limited to, their educational attainment, occupations prior to serving in Congress, and ties to Black Greek Letter organizations. We argue that this descriptive data will prompt new questions for legislative scholars and open conversations about disciplinary norms and assumptions which may need revision in light of Congress’ increasing diversification.

  PublisherDOI

• The Intellectual Benefits of Diversity

  Oxford University Press eBooks · 2024 · 1 citations

  1st authorCorresponding
  • Political Science
  • Political Science
  • Law

  Abstract This chapter highlights the longstanding call for increased diversity, particularly in terms of gender, race, and socioeconomic backgrounds within the field of political science. It specifically focuses on the intellectual advantages of racial diversity in the discipline, contending that it enhances the quality of research. Racial diversity not only brings a variety of research themes but also a range of methodological approaches. Despite significant underrepresentation of Black scholars in political science, they have pioneered innovative research on new subjects and introduced novel methodological techniques. These contributions span various subfields, including international relations, political theory, and race and ethnic politics. The chapter highlights the striking lack of diversity in tenure-track faculty positions at leading PhD-granting institutions and the scarcity of PhDs awarded to Black scholars across various disciplines. The chapter also provides several examples of the theoretical richness and innovations stemming from Black scholars’ work and underscores how these insights may not have arisen from White scholars. It emphasizes the role of identity in shaping research questions, theoretical approaches, and the capability to investigate various topics. In conclusion, the chapter stresses that addressing the demographic imbalances within the profession will enrich political science by enhancing the diversity of theoretical questions, approaches, and the capacity to address crucial research inquiries. It also points out that political science lags behind many related disciplines in terms of demographic diversity, and similar intellectual benefits can be expected if these issues are addressed in other fields like economics, history, psychology, and sociology.

  PublisherDOI

• Citizen science data reveal molt into drab nonbreeding plumage in five woodstar species (Mellisuginae, Trochilidae)

  The Wilson Journal of Ornithology · 2024-09-01 · 11 citations

  article1st authorCorresponding
  PublisherDOI

• Exceptional Plumage of a Female Anna’s Hummingbird in Los Angeles

  Western Birds · 2024-11-30 · 1 citations

  articleSenior author

  Hummingbirds are often sexually dimorphic, the males of many species showing an ornamental gorget that females lack. Males use this ornamental plumage to attract mates and establish a territory, while females build nests and care for the young alone. In Los Angeles, California, we observed a nesting Anna’s Hummingbird with male-like plumage on the crown and gorget but the rectrix morphology of a female—and it reared chicks. The extent of gorget development on this individual likely represents one of the most extreme examples of a male-plumaged female hummingbird yet documented.

  PublisherDOI

• Adaptive hypotheses on the evolution of non-vocal communication sounds in birds

  2024-01-17

  articleOpen access1st authorCorresponding

  The birds have evolved to produce communication sounds(sonations) with their wings, tail, feet, or beak dozens ifnot hundreds of times independently. Ongoing workcontinues to uncover many new examples of sonationsand the physical acoustic mechanisms by which thesesounds are produced. The repeated (convergent)evolution of a trait permits sophisticated evolutionarytests of how and why it evolves. Here, we outline aseries of adaptive questions about the evolution ofsonations: Does producing sonations entail tradeoffswith other functions, such as flight? How do sonationsco-evolve with production of vocalizations? How dosonations co-evolve with behavior? Compared tovocalizations, do sonations occupy the same functionalspace as vocalizations? Do sonations occupy the sameacoustic space as vocalizations? Each of these questionshas already received some attention within individualbird clades, but with so many independent origins acrossbirds, the bigger picture has only begun to appear.

  PublisherOA PDFDOI

Recent grants

• Collaborative Research: Admixture mapping of a hybrid zone to test Tinbergen's emancipation hypothesis

  NSF · $384k · 2017–2023

Frequent coauthors

• Teresa J. Feo

  Smithsonian Institution

  74 shared

• Richard O. Prum

  American Museum of Natural History

  30 shared

• Jacob S. Berv

  University of Michigan–Ann Arbor

  17 shared

• Nicholas R. Atkins

  University of Cambridge

  13 shared

• A.A. Moulthrop

  12 shared

• M.S. Muha

  The Aerospace Corporation

  12 shared

• Andrew Warfield

  Amazon (United States)

  9 shared

• Steven Hand

  Infinera (United States)

  9 shared