Gail L. Patricelli, Ph.D. - US grants

Males of many species produce spectacular courtship displays to attract females to mate. Females may prefer males with elaborate displays because these displays act as signals, conveying information about the male's "quality" as a mate. Males produce these signals, but the signals must transmit through the environment to reach the female. The environment can affect signals during transmission: for example, sound carries better in some environments than others and ambient light can affect how colors appear. Therefore, the signal that reaches the female depends both on what is sent by the male and the environment through which it is transmitted. This may select for males that choose display locations with good transmission properties (e.g. good lighting or good acoustics) to increase the attractiveness of their display. In this research project, greater sage grouse (Centrocercus urophasianus) will be used as a model system to examine the importance of the acoustic environment in influencing both male display behaviors and male success in convincing females to mate. During the breeding season, male sage grouse aggregate on display grounds called "leks" and compete to establish display territories. On their territories, males produce spectacular vocalizations, which females assess when choosing their mates. The "acoustic quality" of male display territories is variable across the lek, and this variation will impact the pitch and loudness of vocalizations perceived by females; for this reason, the acoustic quality of a territory may affect the mating success of the resident male. An Acoustic Localization System (ALS) will be used to create detailed maps of male territories and the locations of favored display sites. ALS is a technique whereby a sound is recorded on multiple microphones, and the difference in the time at which the sound reaches each microphone is used to reconstruct the location of sound source. This ALS data will be combined with measurements of male mating success and the acoustic quality of male display sites to test two hypotheses: 1) that the acoustic quality of a territory impacts the attractiveness of the resident male, and 2) that within their territories, males preferentially display from locations that improve signal transmission.
The results of this project will contribute to our understanding of how the environment affects acoustic communication and courtship in animals. This project will involve the development and refinement of methods for studying acoustic communication and territorial behaviors that can be used by many other researchers. In the process, this research will provide research and training opportunities to undergraduates, graduate students and postdoctoral researchers at the University of California, Davis. Finally, greater sage grouse are federally recognized as a "species of concern", and both the loss of sage-grouse habitat and the increase in human-produced noise are likely causes of their declining numbers. Results from this work will increase our understanding of how different habitat characteristics affect reproduction in sage grouse; this information will inform future decisions about the suitability of habitat for sage grouse. In addition, results from this project will increase our understanding of how sound propagates through the sage-grouse habitat, and will inform the debate on how human-produced noise impacts acoustic communication and reproduction on the lek.

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).


Economists study negotiation as a series of events, including partner choice, information gathering, and haggling. The context in which these negotiations occur--the market--is critical because individuals can adjust their demands in response to those of other players. Animals are faced with similar decisions during reproduction: who to court, how to approach a potential partner, at what level to display compared to competitors and when to give up unsuccessful interactions. Thus, economic models of negotiation in a market provide a framework in which courtship can be viewed as a process in which males and females use a series of tactics to improve their success. This project uses greater sage-grouse (Centrocercus urophasianus) as a model species to examine the importance of tactics used by males during courtship. A combination of experiments and detailed observations will be used, including robotic females to serve as experimental stimuli, multiple microphones and video cameras to record male signals and breeding behaviors. This approach will allow for the experimental study of courtship interactions in a wild population. Using this framework, the investigators expect to show that success in courtship, as in business, requires an attractive offer as well as skilled negotiation. Sage-grouse are currently being considered for federal listing as an endangered species. This project involves collaboration with an environmental education specialist to conduct extensive outreach addressing the role of basic and applied science in management decisions. This work will also compliment the ongoing applied research by the investigator to address how noise pollution may disrupt sage-grouse courtship negotiations and contribute to their population declines. This project involves mentorship and salary for a postdoctoral scholar and graduate students, and mentorship for dozens of undergraduates, many from underrepresented minorities.

The elaborate songs and plumage ornaments of birds are generally thought to advertise male quality; therefore, females that respond to displays should gain a reproductive benefit through increased quantity or quality of offspring. However, in order for females to continue responding, signals must be honest, suggesting that some mechanism prevents males from cheating. For species that breed over multiple years, two processes that contribute to aging may ensure signal honesty by enforcing a trade-off between investment in sexual displays and investment in longevity. One process involves telomeres, which are repeated DNA sequences that serve as protective caps on the ends of each chromosome and shorten with age; the second process, oxidative stress, occurs when the by-products of cellular metabolism damage DNA and other cell constituents. The investigators will measure sexual signals, reproductive success, telomere shortening, and oxidative stress in a wild population of common yellowthroat warblers breeding in upstate New York. They will explore trade-offs between reproductive investment and aging in two ways. First, they will look for relationships between sexual signals, lifetime reproductive success, telomere shortening, and oxidative damage in our long-term data set. Second, they will use hormone implants to experimentally increase reproductive investment and measure the resulting impact on telomere loss and oxidative damage. Individuals that invest heavily in sexual signals are expected to pay a high cost through fast physiological aging and reduced longevity. Understanding the way that complex suites of traits interact to determine lifetime reproductive success is essential in predicting evolutionary outcomes that shape important life history traits, such as aging patterns and reproductive strategies, both within and across species.

Buyers and sellers negotiating in a market face a series of stages from partner choice to information gathering to haggling, etc., with the optimal decisions at each stage depending on both players' bargaining positions. These bargaining positions will depend on the players' assets (income and capital) and outside options for alternative buyers and sellers. Animals face similar decisions regarding courtship, including how much energy to acquire, who to court, how much information to gather, when to give up, etc. In the mating market, males and females haggle during courtship, with their bargaining positions determined by their assets (foraging success and body condition) as well as the number of alternative partners for each. Thus economic models of negotiation in a market provide a framework for viewing courtship as a process where males and females can use tactics to improve their negotiating outcome, using the resources they have available. This project explores this framework using greater sage-grouse (Centrocercus urophasianus) as a model species. New technology will allow experimental study of courtship and detailed observation of foraging behaviors in the wild, with minimal disturbance. Methods include presentations of interactive female robots, next-generation GPS loggers and accelerometers to measure off-lek foraging behaviors, as well as bioanalytical assays of the nutrition and toxicity of sagebrush that grouse prefer to consume. We expect to show that success in courtship, as in business, requires income and capital as well as skilled negotiation. Sage-grouse are a candidate species for listing as endangered. The PIs will conduct multimedia presentations on sage-grouse ecology and conservation for the public, and develop course materials and presentations for primary schools, tribal colleges and universities in sage-grouse habitat. Research by PIs will continue to directly inform sage-grouse conservation efforts. In addition, the PIs will continue to provide research opportunities for students (>175 since 2006), including many from under-represented groups.