Stephen Nowicki, Professor  

Stephen Nowicki

Our lab studies animal communication, asking both proximate and ultimate questions about how signaling systems function and how they evolve. Most of our work is done with birds, although lab members have studied a variety of other taxa. One major theme that runs through our work is to understand how signal reliability (“honesty”) is maintained in the face of the competing evolutionary interests of signal senders and receivers. We use both laboratory experiments and field-based analyses to test hypotheses about the costs of signal production, which theory suggests are necessary to maintain reliability. For example, we have demonstrated that the reliability of birdsong as a signal of quality in the context of mate choice is maintained by variation in the response of young birds to early developmental stress, which in turn affects brain development and song learning. Another theme that runs through our work concerns how animals themselves perceive signals, in particular the role of categorical perception in communication. Our work here began with birdsong, for example demonstrating context-dependent variation in category boundaries that define the smallest acoustic units of song (“notes”), and identifying categorical responses of neurons in the “song system” of the brain to variation in those notes. More recently, we have begun to study categorical perception in visual signaling, demonstrating for example that the carotenoid-based orange-red coloration commonly used in assessment signaling may be perceived categorically. This finding illustrates the connection between our interests in perception and reliability, given that canonical models of reliability assume continuous perception.

Ph.D., Cornell University, 1984
M.S., Tufts University, 1978
B.S., Tufts University, 1976

Office Location: 137 Biological Sciences Building, 130 Science Drive, Durham, NC 27708
Office Phone: (919) 684-6950
Email Address:
Web Page:
Additional Web Page:

Organismal Biology and Behavior
Ecology and Population Biology

Research Categories: Function, structure, and evolution of animal signaling systems

Research Description: The Nowicki Laboratory studies behavioral ecology and neuroethology, especially questions about the function, structure and evolution of animal signaling systems. Although birds serve as a common model system in the lab, Nowicki and his students have worked on a variety of organisms including invertebrates such as insects, spiders, shrimp and lobsters, and other vertebrates including lizards, dolphins and primates. Steve Nowicki’s long-time research associate (and wife) is Susan Peters. Their current work lies in three main areas. The first, done in collaboration with Bill Searcy (University of Miami), concerns the evolution of signal reliability. In the context of sexual signaling, this work has focused on how early developmental stress affects brain development and song learning in birds, thus making song a reliable signal of male quality in mate choice by females. In the context of aggressive signaling in males, recent work has examined how particular vocal and visual signaling behaviors reliably predict attacks in aggressive encounters, and how receiver-retaliation imposes a cost that maintains this reliability. A second main line of research, done in collaboration with Rich Mooney (Duke Medical School), uses the learning, development, and perception of birdsong as a model system to study brain mechanisms underlying communication. Here, recent work focuses on categorical perception of signal features, both how neurons in the bird’s brain exhibit categorical responses to salient signal features and how categorical perceptual boundaries vary geographically as a consequence of learning. A third research program, also in collaboration with Bill Searcy, examines the interplay between cognition and communication, with the goal of understanding how cognitive abilities necessary for song learning and signaling associate with phenotypic and genetic differences (notably degree of inbreeding) among individuals in a population and how these associations map onto fitness and mate choice in the wild.

Areas of Interest:
evolution of animal signaling systems
neural basis of communication

Recent Publications   (More Publications)   (search)

  1. Searcy, WA; Chronister, LM; Nowicki, S, Syntactic rules predict song type matching in a songbird, Behavioral Ecology and Sociobiology, vol. 77 no. 1 (January, 2023) [doi]  [abs].
  2. Peters, S; Soha, J; Searcy, WA; Nowicki, S, Are song sequencing rules learned by song sparrows?, Animal Behaviour, vol. 192 (October, 2022), pp. 75-84 [doi]  [abs].
  3. Davis, A; Zipple, MN; Diaz, D; Peters, S; Nowicki, S; Johnsen, S, Influence of visual background on discrimination of signal-relevant colours in zebra finches (Taeniopygia guttata)., Proceedings of the Royal Society B: Biological Sciences, vol. 289 no. 1976 (June, 2022), pp. 20220756 [doi]  [abs].
  4. Green, PA; George, EM; Rosvall, KA; Johnsen, S; Nowicki, S, Testosterone, signal coloration, and signal color perception in male zebra finch contests., Ethology, vol. 128 no. 2 (February, 2022), pp. 131-142 [doi]  [abs].
  5. Searcy, WA; Nowicki, S, Animal communication, in The Behavior of Animals: Mechanisms, Function and Evolution, edited by Bolhuis, JJ; Giraldeau, L-A; Hogan, JA (January, 2022), pp. 367-396, WILEY-BLACKWELL  [abs].