Projects

We are grateful for the National Science Foundation of China (NSFC) for funding some of our research on mixed-species flocks and bird communication.

NSFC Regional grant 31560119 (2016-2019) was entitled “Understanding leadership and the interdependencies of species in mixed-species bird flocks: from southern China to the Hengduan Mountains.” In this grant, we survey mixed-species bird flocks located in two reserves in Guangxi and three reserves in Yunnan, covering a range of elevations from 400 to 3200 m. Transects were placed across a habitat gradient, including relatively undisturbed forest, buffer habitats and intensive agriculture.  We saw a total of 375 flocks over 2 years, and found that one major system, led by fulvettas (Alcippe spp.) was dominant in undisturbed forest over most of the elevational gradient (up to 2900 m). Leadership changed, however, in buffer areas, especially in seeded pine, where fulvetta-led flocks were not found, and the system declined sharply in agriculture. We concluded that finding ways to maintain fulvetta-led flocks in buffer habitat is an important way to maintain biodiversity in human-modified areas.

Figure 1. Eben Goodale (right) and colleagues Mingxia Zhang (middle) and Chao Zhao (left) at look out in the Gaoligong Mountains, Yunnan.

Figure 1. Eben Goodale (right) and colleagues Mingxia Zhang (middle) and Chao Zhao (left) at look out in the Gaoligong Mountains, Yunnan.

A follow-up study sought to understand what birds gain from following leading species. Working in Ailaoshan National Nature Reserve in Yunnan, we did a playback experiment in which birds were exposed to the sounds of a mixed-species flock, or the vocalizations of a single species, including those of the primary leader, Yunnan Fulvetta, two secondary leaders, two followers, and one non-flocking species. We also included a playback treatment of an owl, which provokes birds to mob. We found surprisingly that response was relatively even among treatments, which suggests that birds are using the sounds of other mixed-species participants to find a flock. We conclude that both mobbing and flocking are adaptations to lower predation risk, and that birds respond rather similarly to these very different stimuli.

Data papers that came from this project:

  1. Zhou, L., Peabotuwage, I., Luo, K., Quan, R.-C., Goodale, E. 2021. Using playback to test leadership in mixed-species flocks, and compare flocking with mobbing. Animal Behaviour 180: 151-166.
  2. Zhou, L., Peabotuwage, I., Gu, H., Jiang, D., Jiang, A., Zhang, M., Quan, R., and Goodale, E.  2019. The response of mixed-species flocks to anthropogenic disturbance and elevational variation in southwest China. Condor 121: 1-13.

NSFC General grant 31770424 (2018-2021) was entitled “The content of the contact call: Information transfer in monospecific and mixed-species groups of birds.” In this project we were intrigued by the function of contact calls, which are common repetitive vocalizations often made by group-living birds and mammals.  These vocalizations are clearly related to group cohesion, but their exact function, and what stimulates changes in contact call rate, are not well understood, especially for birds. We hypothesized that contact calls would be connected to environmental conditions, and specifically that a) their cessation would signal predation threat, b) rate would vary with vegetation density, and c) calls would be used in the context of food discovery. However, our research, using Swinhoe’s White-eye, Zosterops simplex, as a model, consistently suggested otherwise.  Silence did not invoke an alarm response from birds nor intensive their response to alarm calls, and vegetation did not affect birds contact call rate either in the field or the lab.  Instead, contact call rate was related to social circumstances: to movement of birds into the center of the flock (in the field), and when birds were housed in groups of affiliated individuals (in the aviary).

Figure 2. Aiwu Jiang (middle) shows Estelle Meaux (left) and Ruchuan He (right) how to measure birds in the Guangxi University aviary.

Figure 2. Aiwu Jiang (middle) shows Estelle Meaux (left) and Ruchuan He (right) how to measure birds in the Guangxi University aviary.

Leading species in mixed-species flocks noticeably make a lot of contact calls, so we wanted to know if following species might learn about environmental conditions by listening to the contact calls of leaders. We also wanted to test the “trapped leader” hypothesis of flock organization, which suggests that followers benefit from leaders, but not vice versa. So we proposed to run an “heterospecific audience effect” experiment, in which we could see if the presence of followers influenced how the leading species produces vocalizations. Unfortunately, a series of logistical and methodological problems did not allow us to conduct the experiment on contact calls as planned. However in on-going experiments, we are attempting to investigate a similar question, hypothesizing that leaders will aim their mobbing calls towards followers, diluting their risk, which would demonstrate that the trapped leader hypothesis may not capture all the complexities of species interactions possible in flocks.

Data papers that came from this project:

1) Meaux, E., Peabotuwage, I., Mammides, C., Malykhina, K., Quan, R.-C., Goodale, E. 2021. Behavioural variables influence contact call rate more than characteristics of the vegetation in a group-living passerine species. Behavioural Processes 185: 104345.

2) Meaux, E., He, C., Qiu, L. and Goodale, E. 2021. The cessation of contact calls does not provoke or modulate alarm behaviour in a social passerine. Behaviour. DOI: 10.1163/1568539X-bja10117

During the time that we were conducting these projects, we were also excited to work with an international network of collaborators interested in mixed-species flocks throughout the world. We helped organize two symposia, one at Ecosummit in 2016, and one held entirely online in 2021 (see “Mixed-species flock symposium page”). These collaborations also led to several synthetic articles on mixed-species animal groups of different habitats and taxa:

  1. Goodale, E., Beauchamp, G. and Ruxton, G. D. 2017. Mixed-species animal groups: Behavior, community structure and conservation.  Academic Press. ISBN: 9780128053553.
  2. Goodale, E., Ruxton, G. D., Beauchamp, G. 2019. Predatory eavesdropping in a mixed-species environment: How prey species may use grouping, confusion, and the cocktail party problem to reduce predator detection. Frontiers in Ecology and Evolution 7:141.
  3. Goodale, E., Sridhar, H., Sieving, K., Bangal, P., Colorado, G., Farine, D., Heymann, E. W., Jones, H., Krams, I., Martínez, A. E., Montaño-Centellas, F., Muñoz, J., Srinivasan, U., Theo, A., Shanker, K. 2020. Mixed company: A framework for understanding the composition and organization of mixed-species animal groups. Biological Reviews 95: 889-910.

We are also grateful for the support of a Special Talent Recruitment Grant from Guangxi University. This grant has allowed us to explore agroecology in Guangxi, the concentrations of heavy metals in birds of Guangxi and elsewhere in China, and how birds change across an urbanization gradient in their foraging niches. Thanks to all our funders for their support and encouragement, which has led to an excellent atmosphere for research.

 

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