Photo by Adam
Project Introduction
Anthropogenic noise is ubiquitous across the world and, aside from other negative effects, causes declines in abundance and species richness in birds [1]. How anthropogenic noise does this is not yet well understood, although anthropogenic noise disrupting biologically important cues seems to be a key factor [2]. Although anthropogenic noise masks (covers up) sexual and anti-predatory signals, declines in abundance can happen quickly (within 4 days) after the onset of noise [3] suggesting that masked signals may be ones used more frequently. One such important and frequently used signal that has received considerable attention in primates and cetaceans, but little in birds, are calls used to coordinate group movement [4].
When foraging and traveling between patches in their environment, many flocking birds produce vocalizations often referred to in the literature as 'contact', ‘flight’, or ‘feeding’ calls, which are thought maintain group cohesion and coordinate group movement [5]. These auditory cues are thought to be critical in habitats with visual barriers (i.e. forests) [6] as auditory cues can travel much farther than visual cues in these types of habitats and can provide information about multiple signallers’ positions relative to the receiver in all directions. Like some primates and cetaceans, bird species that occur in similarly visually restrictive environments and produce 'contact' calls likely rely on these vocalizations to coordinate group movement [7]. While vocal coordination of group movement in mammals is somewhat understood, evidence is weak regarding how vocalizations function to maintain group cohesion and coordinate group movement in social avian species [8]. To establish if disrupting these vocalizations impacts flocking behaviour in birds, the mechanisms behind vocal coordination of group movement must be understood. To determine how these vocalizations function to coordinate group movement the correlation between these vocalizations and group movement patterns need to be established. Until now there has been no way to conduct experiments that take advantage of the behaviour of all individuals into account, while simultaneously linking their movements, visual field, and vocalizations across multiple habitats. Without understanding the mechanisms behind the coordination group behaviours, determining the effects of factors such as anthropogenic noise on these behaviours remains elusive.
Anthropogenic noise is garnering much interest from the bioacoustics and conservation communities in particular due to its ability to disrupt vocally-mediated behaviours. And while many species can compensate for this disruption by changing signal amplitude, timing, frequency, duration, and redundancy [9], this is not true for all species. Anthropogenic noise causes problems for females searching for singing mates and causes lower or no response to anti-predator signals [10]. Anthropogenic noise, probably, then, has similar effects on the vocalizations used to maintain group cohesion and coordinate group movement. As flocking can increase foraging and anti-predator benefits of groups [11], disrupting group coordination signals will likely lead to flocks getting smaller, or even breaking apart all together.
With the project we aim to establish a fundamental understanding of how vocalizations coordinate group movement which will allow us to determine the impact of anthropogenic noise on this behaviour, and will provide the foundation for further study into other vocally mediated group behaviours. To do this we will address the following questions:
How do birds use vocalizations to coordinate group movement?
What calls are used during group movement?
Do birds use specific call types for different states (foraging, traveling, etc.)?
Do they change their calling behaviour in response to group movement or does group movement change in response to changes in calling behaviour?
How does anthropogenic noise affect a flock’s ability to coordinate group movement?
How does the visual environment (ability to maintain visual contact) affect the use of vocalizations across different group movement scenarios?
How does the acoustic environment (level of noise) affect the use of vocalizations across different group movement scenarios?
Can flocks compensate for poor visual or acoustic conditions by relying more heavily on the other signal type (visual or acoustic)?
We are using two tracking systems in the Imaging Barn to determine both how birds use vocalizations to coordinate group movement, as well as the effects of anthropogenic noise in different habitats. The first tracking system is the VICON system. This system tracks infrared reflective markers in unique patterns that the starlings wear on a backpack in 3D space. It has sub-millimeter precision and rotational measurements as well as position in space. This means we are planning to use these rotational measurements to determine the behaviour of the birds (i.e. are they foraging, flying, preening, sleeping, etc.). The second system is the acoustic array. This is an array of microphones designed by Dr. Jens Koblitz, which allows us to localize where a sound comes from. By combining data from both sources we can track where all individuals are at any time, as well as when every individual calls and from where.
Anthropogenic noise is ubiquitous across the world and, aside from other negative effects, causes declines in abundance and species richness in birds [1]. How anthropogenic noise does this is not yet well understood, although anthropogenic noise disrupting biologically important cues seems to be a key factor [2]. Although anthropogenic noise masks (covers up) sexual and anti-predatory signals, declines in abundance can happen quickly (within 4 days) after the onset of noise [3] suggesting that masked signals may be ones used more frequently. One such important and frequently used signal that has received considerable attention in primates and cetaceans, but little in birds, are calls used to coordinate group movement [4].
When foraging and traveling between patches in their environment, many flocking birds produce vocalizations often referred to in the literature as 'contact', ‘flight’, or ‘feeding’ calls, which are thought maintain group cohesion and coordinate group movement [5]. These auditory cues are thought to be critical in habitats with visual barriers (i.e. forests) [6] as auditory cues can travel much farther than visual cues in these types of habitats and can provide information about multiple signallers’ positions relative to the receiver in all directions. Like some primates and cetaceans, bird species that occur in similarly visually restrictive environments and produce 'contact' calls likely rely on these vocalizations to coordinate group movement [7]. While vocal coordination of group movement in mammals is somewhat understood, evidence is weak regarding how vocalizations function to maintain group cohesion and coordinate group movement in social avian species [8]. To establish if disrupting these vocalizations impacts flocking behaviour in birds, the mechanisms behind vocal coordination of group movement must be understood. To determine how these vocalizations function to coordinate group movement the correlation between these vocalizations and group movement patterns need to be established. Until now there has been no way to conduct experiments that take advantage of the behaviour of all individuals into account, while simultaneously linking their movements, visual field, and vocalizations across multiple habitats. Without understanding the mechanisms behind the coordination group behaviours, determining the effects of factors such as anthropogenic noise on these behaviours remains elusive.
Anthropogenic noise is garnering much interest from the bioacoustics and conservation communities in particular due to its ability to disrupt vocally-mediated behaviours. And while many species can compensate for this disruption by changing signal amplitude, timing, frequency, duration, and redundancy [9], this is not true for all species. Anthropogenic noise causes problems for females searching for singing mates and causes lower or no response to anti-predator signals [10]. Anthropogenic noise, probably, then, has similar effects on the vocalizations used to maintain group cohesion and coordinate group movement. As flocking can increase foraging and anti-predator benefits of groups [11], disrupting group coordination signals will likely lead to flocks getting smaller, or even breaking apart all together.
With the project we aim to establish a fundamental understanding of how vocalizations coordinate group movement which will allow us to determine the impact of anthropogenic noise on this behaviour, and will provide the foundation for further study into other vocally mediated group behaviours. To do this we will address the following questions:
How do birds use vocalizations to coordinate group movement?
What calls are used during group movement?
Do birds use specific call types for different states (foraging, traveling, etc.)?
Do they change their calling behaviour in response to group movement or does group movement change in response to changes in calling behaviour?
How does anthropogenic noise affect a flock’s ability to coordinate group movement?
How does the visual environment (ability to maintain visual contact) affect the use of vocalizations across different group movement scenarios?
How does the acoustic environment (level of noise) affect the use of vocalizations across different group movement scenarios?
Can flocks compensate for poor visual or acoustic conditions by relying more heavily on the other signal type (visual or acoustic)?
We are using two tracking systems in the Imaging Barn to determine both how birds use vocalizations to coordinate group movement, as well as the effects of anthropogenic noise in different habitats. The first tracking system is the VICON system. This system tracks infrared reflective markers in unique patterns that the starlings wear on a backpack in 3D space. It has sub-millimeter precision and rotational measurements as well as position in space. This means we are planning to use these rotational measurements to determine the behaviour of the birds (i.e. are they foraging, flying, preening, sleeping, etc.). The second system is the acoustic array. This is an array of microphones designed by Dr. Jens Koblitz, which allows us to localize where a sound comes from. By combining data from both sources we can track where all individuals are at any time, as well as when every individual calls and from where.
References
[1] Francis, Ortega, & Cruz, Curr Biol 19, 1415–1419 (2009); McClure, Ware, Carlisle, Kaltenecker & Barber, Proc R Soc B 280, 20132290 (2013).
[2] McClure, et al., Proc R Soc B 280, 20132290 (2013); Shannon, et al. Biol Rev 91, 982–1005 (2015); Ortega, Ornithol Monogr 74, 6–22 (2012).
[3] McClure, et al., Proc R Soc B 280, 20132290 (2013).
[4] Kappeler, Animal Behaviour: Evolution and Mechanisms (2010); Crane, et al., Emu 116, 241–13 (2016); Radford, Ethology 110, 11–20 (2004).
[5] Crane, et al., Emu 116, 241–13 (2016); Farnsworth, Auk 122, 733–746 (2005); Marler, Ann NY Acad Sci 1016, 31–44 (2004).
[6] Bradbury & Vehrencamp, Principles of Animal Communication. (1998); Kondo & Watanabe, Jpn Psychol Res 51, 197–208 (2009).
[7] Boinski & Campbell, Behaviour 875–901 (1995); Crane, et al., Emu 116, 241–13 (2016); Kondo & Watanabe, Jpn Psychol Res 51, 197–208 (2009).
[8] Caro, Antipredator defences in birds and mammals. (2005); Boinski & Garber, On the Move. (2000).
[9] Brumm, Animal Communication and Noise, (2013).
[10] Ortega, Ornithol Monogr 74, 6–22 (2012); Francis & Barber, Front Ecol Environ 11, 305–313 (2013).
[11] Caro, Antipredator defences in birds and mammals. (2005).
[1] Francis, Ortega, & Cruz, Curr Biol 19, 1415–1419 (2009); McClure, Ware, Carlisle, Kaltenecker & Barber, Proc R Soc B 280, 20132290 (2013).
[2] McClure, et al., Proc R Soc B 280, 20132290 (2013); Shannon, et al. Biol Rev 91, 982–1005 (2015); Ortega, Ornithol Monogr 74, 6–22 (2012).
[3] McClure, et al., Proc R Soc B 280, 20132290 (2013).
[4] Kappeler, Animal Behaviour: Evolution and Mechanisms (2010); Crane, et al., Emu 116, 241–13 (2016); Radford, Ethology 110, 11–20 (2004).
[5] Crane, et al., Emu 116, 241–13 (2016); Farnsworth, Auk 122, 733–746 (2005); Marler, Ann NY Acad Sci 1016, 31–44 (2004).
[6] Bradbury & Vehrencamp, Principles of Animal Communication. (1998); Kondo & Watanabe, Jpn Psychol Res 51, 197–208 (2009).
[7] Boinski & Campbell, Behaviour 875–901 (1995); Crane, et al., Emu 116, 241–13 (2016); Kondo & Watanabe, Jpn Psychol Res 51, 197–208 (2009).
[8] Caro, Antipredator defences in birds and mammals. (2005); Boinski & Garber, On the Move. (2000).
[9] Brumm, Animal Communication and Noise, (2013).
[10] Ortega, Ornithol Monogr 74, 6–22 (2012); Francis & Barber, Front Ecol Environ 11, 305–313 (2013).
[11] Caro, Antipredator defences in birds and mammals. (2005).
