Source: CORNELL UNIVERSITY submitted to
LOON VOCAL RECOGNITION
Sponsoring Institution
State Agricultural Experiment Station
Project Status
TERMINATED
Funding Source
STATE
Reporting Frequency
Annual
Accession No.
0159724
Grant No.
(N/A)
Project No.
NYC-191351
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 1997
Project End Date
Sep 30, 2009
Grant Year
(N/A)
Project Director
Walcott, C.
Recipient Organization
CORNELL UNIVERSITY
(N/A)
ITHACA,NY 14853
Performing Department
NEUROBIOLOGY AND BEHAVIOR
Non Technical Summary
(N/A)
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1350820107050%
1350860107050%
Knowledge Area
135 - Aquatic and Terrestrial Wildlife;

Subject Of Investigation
0860 - Endangered species; 0820 - Wild birds;

Field Of Science
1070 - Ecology;
Goals / Objectives
The "Yodel" call of the Common Loon, Gavia immer, is an acoustical territorial signal. If individual recognition is to be found in any of the loon's vocalizations, the yodel is the most likely. Since loons are threatened in much of the Eastern United States, there is great interest in being able to identify individual loons without the necessity of capturing and banding them. If the yodel consistently signals a male loon's individuality, "vocal tagging", recognizing an individual loon by it's call, would be feasible.
Project Methods
To test this idea we have recorded the yodels of a banded population of male loons at the Seney National Wildlife Refuge on Michigan's Upper Peninsula. Using a computer based sound analysis program, Canary, we have analyzed the yodels of 6 loons over a period of 6 years. Using multivariate analysis we can recognize the characteristics of the yodel of each individual loon. Yodels are stable from year to year; the differences between loons are greater than the year to year differences of individual birds. Last year we recorded yodels from a loon as it switches its territory. The B-Pool South loon was challenged by the male from T2 West. The B-Pool loon was ejected and took up residence on B-Pool North. As it did so, its yodel changed significantly. The yodel of the T2 male that replaced it also changed to more closely resemble that of the old B-Pool male. If such changes in yodels with changing territories are common, it will make vocal tagging impossible. We will continue these observations of marked loons to see how often loons change their yodels when they change their territories.

Progress 10/01/08 to 09/30/09

Outputs
OUTPUTS: Common Loons, Gavia immer, are highly territorial on their breeding lakes. We have been investigating how Loons establish and maintain their territories. Male and female loons establish their territories independently; if a male loon is displaced or dies another male loon will replace him and mate with the female on the territory. The same thing is true of the female loon. But the contests that result in takeovers of the territory are very different in males and females. Female fights are genteel affairs, splashing, chasing and diving underwater. The losing female takes up residence either on a large lake nearby or on a vacant territory. In contrast, male fights are long drawn out and fatal roughly 30% of the time. If a male is killed, it is always the resident, never the intruder. Further, it is usually the older, lighter males that are involved in the fatal fights. We believe that the reason for this difference in outcomes is that it is the male loon, not the female who determines where to place the nest. The male has a simple rule: if the nest is successful, pick the same location the next year. If it fails, move. The first year on a territory the male has a reproductive success of about 45%; by the 8th year it has increased to nearly 70%. For a female, the reproductive success depends entirely on the male. Thus a displaced female can pick a new territory and a new mate without penalty but a male faces an enormous loss in reproductive potential when it changes territory. Presumably it is that difference that gives rise to fatal fighting in the males. Male loons on a territory lose weight every year; females do not. The heavier a male, the better territory he can obtain and the longer he can maintain it. The male's vocalization, the yodel,, not only is specific to the individual but it also codes for the size of the male. Thus, smaller and more vulnerable males have higher pitched yodels. One would predict that smaller males would yodel less frequently than large males and that appears to be the case. The yodel also codes for the aggressive state of the male; the longer the yodel, the greater the threat perceived by the male. Increasing territory quality by putting out nesting platforms greatly increases the displacement rate of territorial males and increases the length of their yodels. One would predict that playing low pitched yodels to intruding males would be more effective than high pitched yodels in preventing their landing; this remains to be tested. Recently, we have found that the Wail call of both male and female loons is individually distinctive, but we do not yet know how stable these differences are from year to year nor when a loon changes its territory. PARTICIPANTS: Collaborators: Walter Piper, Associate Professor, Chapman University, Orange, CA John H. Mager, Assistant Professor, Ohio Northern University, Ada , Ohio Summer research assistant: Lyla Rudgers, Cornell University, undergraduate The undergraduate students were trained in data collection and spent the summer gathering the raw field data upon which all the analysis is based. Jay Mager recorded the loon vocalizations and Dan Salisbury and Lyla Rudgers did the computer analysis during the year. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Loons compete with vacation cottages for lakeshore frontage to nest on and the increasing recreational use of lakes poses a potential threat to their population. In addition, methyl mercury tends to increase in loon population impeding reproduction. By understanding the social system of loons and their use of territory, we can make recommendations to reduce this potential conflict. Clearly nest platforms can replace shore frontage for loon nesting, but too great a density of platforms results in endless male battles and little reproduction. The secret to preserving loon populations is really public education based on the loon biology we are learning. A 50 minute video describing this work is available at: http://www.cybertower.cornell.edu/lodetails.cfmid=163

Publications

  • No publications reported this period


Progress 10/01/07 to 09/30/08

Outputs
OUTPUTS: Common Loons, Gavia immer, are highly territorial on their breeding lakes. We have been investigating how Loons establish and maintain their territories. Male and female loons establish their territories independently; if a male loon is displaced or dies another male loon will replace him and mate with the female on the territory. The same thing is true of the female loon. But the contests that result in takeovers of the territory are very different in males and females. Female fights are genteel affairs, splashing, chasing and diving underwater. The losing female takes up residence either on a large lake nearby or on a vacant territory. In contrast, male fights are long drawn out and fatal roughly 30% of the time. If a male is killed, it is always the resident, never the intruder. Further, it is usually the older, lighter males that are involved in the fatal fights. We believe that the reason for this difference in outcomes is that it is the male loon, not the female who determines where to place the nest. The male has a simple rule: if the nest is successful, pick the same location the next year. If it fails, move. The first year on a territory the male has a reproductive success of about 45%; by the 8th year it has increased to nearly 70%. For a female, the reproductive success depends entirely on the male. Thus a displaced female can pick a new territory and a new mate without penalty but a male faces an enormous loss in reproductive potential when it changes territory. Presumably it is that difference that gives rise to fatal fighting in the males. Male loons on a territory lose weight every year;females do not. The heavier a male, the better territory he can obtain and the longer he can maintain it. The male's vocalization, the yodel,, not only is specific to the individual but it also codes for the size of the male. Thus, smaller and more vulnerable males have higher pitched yodels. One would predict that smaller males would yodel less frequently than large males and that appears to be the case. The yodel also codes for the aggressive state of the male; the longer the yodel, the greater the threat perceived by the male. Increasing territory quality by putting out nesting platforms greatly increases the displacement rate of territorial males and increases the length of their yodels. One would predict that playing low pitched yodels to intruding males would be more effective than high pitched yodels in preventing their landing; this remains to be tested. We do know that at night loons vocalize more in response to low than to high pitched yodels. PARTICIPANTS: Walter Piper, Associate Professor, Chapman University, Orange, CA John H. Mager, Assistant Professor, Ohio Northern University, Ada , Ohio Summer research assistant: Daniel Salisbury, Cornell University, undergraduate The undergraduate students were trained in data collection and spent the summer gathering the raw field data upon which all the analysis is based. Jay Mager recorded the loon vocalizations and Dan Salisbury did the computer analysis during the year. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Loons compete with vacation cottages for lakeshore frontage to nest on and the increasing recreational use of lakes poses a potential threat to their population. By understanding the social system of loons and their use of territory, we can make recommendations to reduce this potential conflict. Clearly nest platforms can replace shore frontage for loon nesting, but too great a density of platforms results in endless male battles and little reproduction. The secret to preserving loon populations is really public education based on the biology we are learning.

Publications

  • Piper, W.H, Walcott, C., Mager, J.H., Spilker, F.J. 2007 Nestsite selection by male loons leads to sex-biased site familiarity. J. Animal Ecology 77: 205-210. Mager, J.H., Walcott, C. Piper, W.H. 2007 Nest platforms increase aggressive behavior in common loons. Naturwisseschaften. 95: 141-147. Piper, W.H., Walcott, C., Mager, J.H. Spilker, F. J. 2008 Fatal battles in common loons: a preliminary analysis. Animal Behavior 75: 1109-1115.


Progress 10/01/06 to 09/30/07

Outputs
OUTPUTS: Common Loons, Gavia immer, are highly territorial on their breeding lakes. We have been investigating how Loons establish and maintain their territories. Male and female loons establish their territories independently; if a male loon is displaced or dies another male loon will replace him and mate with the female on the territory. The same thing is true of the female loon. But the contests that result in takeovers of the territory are very different in males and females. Female fights are genteel affairs, splashing, chasing and diving underwater. The losing female takes up residence either on a large lake nearby or on a vacant territory. In contrast, male fights are long drawn out and fatal roughly 30% of the time. If a male is killed, it is always the resident, never the intruder. Further, it is usually the older, lighter males that are involved in the fatal fights. We believe that the reason for this difference in outcomes is that it is the male loon, not the female who determines where to place the nest. The male has a simple rule: if the nest is successful, pick the same location the next year. If it fails, move. The first year on a territory the male has a reproductive success of about 45%; by the 8th year it has increased to nearly 70%. For a female, the reproductive success depends entirely on the male. Thus a displaced female can pick a new territory and a new mate without penalty but a male faces an enormous loss in reproductive potential when it changes territory. Presumably it is that difference that gives rise to fatal fighting in the males. Male loons on a territory lose weight every year, females do not. The heavier a male, the better territory he can obtain and the longer he can maintain it. The male's vocalization, the yodel,, not only is specific to the individual but it also codes for the size of the male. Thus, smaller and more vulnerable males have higher pitched yodels. One would predict that smaller males would yodel less frequently than large males and that appears to be the case. The yodel also codes for the aggressive state of the male; the longer the yodel, the greater the threat perceived by the male. Increasing territory quality by putting out nesting platforms greatly increases the displacement rate of territorial males and increases the length of their yodels. One would predict that playing low pitched yodels to intruding males would be more effective than high pitched yodels in preventing their landing; this remains to be tested. We do know that at night loons vocalize more in response to low than to high pitched yodels. PARTICIPANTS: Collaborators: Walter Piper, Associate Professor, Chapman University, Orange, CA John H. Mager, Assistant Professor, Ohio Northern University, Ada , Ohio Summer research assistants: Jessica Walden, Cornell University, undergraduate Ben Rubin, Cornell University, undergraduate Beth Ahers, Chapman University, undergraduate The undergraduate students wewre trained in data collection and spent the summer gathering the raw field data upon which all the analysis is based. Jay Mager recorded the loon vocalizations and Jessica Walden did the computer analysis during the year.

Impacts
Loons compete with vacation cottages for lakeshore frontage to nest on and the increasing recreational use of lakes poses a potential threat to their population. By understanding the social system of loons and their use of territory, we can make recommendations to reduce this potential conflict. Clearly nest platforms can replace shore frontage for loon nesting, but too great a density of platforms results in endless male battles and little reproduction. The secret to preserving loon populations is really public education based on the biology we are learning.

Publications

  • Mager, J.N., III, Walcott, C., Piper, W. 2007. Male common loons, Gavia immer, communicate body mass and condition through dominant frequencies of territorial yodels. Animal Behaviour 73:683-690.
  • Mager, J.N., Walcott, C., and Evers, D. 2007. Macrogeographic variation in body size and territorial vocalizations of male Common Loons (Gavia immer). Waterbirds 30 (1): 64-72.


Progress 01/01/06 to 12/31/06

Outputs
Common Loons, Gavia immer, are highly territorial on their breeding lakes. We have been investigating how Loons establish and maintain their territories. Male and female loons establish their territories independently; if a male loon is displaced or dies another male loon will replace him and mate with the female on the territory. The same thing is true of the female loon. But the contests that result in takeovers of the territory are very different in males and females. Female fights are genteel affairs, splashing, chasing and diving underwater. The losing female takes up residence either on a large lake nearby or on a vacant territory. In contrast, male fights are long drawn out and fatal roughly 30 percent of the time. If a male is killed, it is always the resident, never the intruder. Further, it is usually the older, lighter males that are involved in the fatal fights. We believe that the reason for this difference in outcomes is that it is the male loon, not the female who determines where to place the nest. The male has a simple rule: if the nest is successful, pick the same location the next year. If it fails, move. The first year on a territory the male has a reproductive success of about 45 percent; by the 8th year it has increased to nearly 70 percent. For a female, the reproductive success depends entirely on the male. Thus a displaced female can pick a new territory and a new mate without penalty but a male faces an enormous loss in reproductive potential when it changes territory. Presumably it is that difference that gives rise to fatal fighting in the males. Male loons on a territory lose weight every year, females do not. The heavier a male, the better territory he can obtain and the longer he can maintain it. The male's vocalization, the yodel,, not only is specific to the individual but it also codes for the size of the male. Thus, smaller and more vulnerable males have higher pitched yodels. One would predict that smaller males would yodel less frequently than large males and that appears to be the case. The yodel also codes for the aggressive state of the male; the longer the yodel, the greater the threat perceived by the male. Increasing territory quality by putting out nesting platforms greatly increases the displacement rate of territorial males and increases the length of their yodels. One would predict that playing low pitched yodels to intruding males would be more effective than high pitched yodels in preventing their landing; this remains to be tested. We do know that at night loons vocalize more in response to low than to high pitched yodels.

Impacts
Loons compete with vacation cottages for lakeshore frontage to nest on and the increasing recreational use of lakes poses a potential threat to their population. By understanding the social system of loons and their use of territory, we can make recommendations to reduce this potential conflict. Clearly nest platforms can replace shore frontage for loon nesting, but too great a density of platforms results in endless male battles and little reproduction. The secret to preserving loon populations is really public education based on the biology we are learning.

Publications

  • Walcott, C., Mager, J. and Piper, W. 2006. Changing territories, changing tunes: male lkoons Gavia immer, change their vocalization when they change territories. Animal Behaviour 71: 673-683.
  • Mager, J. 2005. What information is communicated by the territorial yodel of male common loons (Gavia immer)? PhD Dissertation Cornell University.
  • Piper, W., Walcott, C., Mager, J., Perala, M., Tischler, K., Harrington, E., Turcotte, A., Schwabenlander, M. and Banfield, N. 2006. Prospecting in a solitary breeder: chick production elicits territorial intrusions in common loons. Behavioral Ecology 17: 881-888.


Progress 01/01/05 to 12/31/05

Outputs
This is one year of a long term, on-going study. The results of the study of territorial calls of the male loons, the Yodel, as described in last year's report, have been written up for publication and accepted by Animal Behaviour. A second paper, describing how a prospecting male loon decides which lake territory to try to take over has been submitted to Behavioral Ecology. The major discovery this year is how important the male Loon is to the reproductive success of the pair. Male loons tend to lose weight every year on a territory; females do not. Incubation, chick rearing and other aspects of reproduction appear to be shared equally by the two sexes. Thus males should be at no more risk of losing weight than females. But there are two important differences; first, it is the male that engages in the most vigorous territorial defense and second, it is the male that determines the location of the nest. Since nest location is a major factor in determining reproductive success, this is clearly an important issue. Male and female loons maintain their pair bond only while on the breeding territory. About 15 to 20% of the time a new male or a new female will intrude and take over an established territory. If it is the female that is displaced, she will move to an adjacent vacant territory. But a displaced male is either killed or leaves the study area entirely. If a new female takes over a territory, the reproductive success stays constant, but if a new male takes over, reproductive success fall by half. Heavier males are more successful in acquiring and defending territories. Their weight is communicated by the pitch of their territorial vocalization, the Yodel. As a male on a territory gradually loses weight, year by year, the pitch of the yodel increases, thus signaling to potential intruders a male potential vulnerability. On the other hand, the rate of yodeling is much higher for large loons than small. Exactly how this change in the yodel plays out in territory maintenance is still to be understood.

Impacts
The hope is that understanding the Loon's social behavior and its ecology will help resolve conflicts between humans and loons. Artificial nesting platforms can greatly increase loon reproductive success over a several year time span, but too great a density of platforms reduces reproductive success.

Publications

  • No publications reported this period


Progress 01/01/04 to 12/31/04

Outputs
Using canonical discriminant analysis and measuring the change in canonical factors, we find that the yearly change of the same loon on the same lake averages about 1.12 units. But different loons on different lakes have an average difference of 2.48 units. Thus the yearly change is significantly less than the difference from one loon to another. The surprise is that when a male loon changes lakes either because it displaces another loon or is itself displaced, its yodel changes by an average of 3.37 units. Exactly why this change takes place is not clear; it might be because in changing lakes a male loon also changes its female partner. To test this idea we looked at situations where the female was displaced and a new female took over a territory while the male remained the same. Under these circumstances the yodel changed an average of 1.28 units, not significantly different from the normal year toyear change. It could be that the male changes to have a different yodel than its neighbors; we have 8 loons that switched where we have good recordings of its neighbors. In 2 of these the yodel became similar and in 5 different. Looking at the previous resident of the territory, we found that all the males that switched changed their yodel in such a way as to increase the difference between their yodel and that of the previous resident. Clearly, vocal tagging is not a useful technique for identifying individual loons. All this research is taking place in the context of examining the selection and maintenance of breeding territories in loons. The yodel is an important territorial signal and we have found that it encodes the size of the loon; bigger loons have lower pitched yodels. Further, playing back tape recordings of yodels shows that there is a greater response from resident loons to lower rather than to higher pitched yodels. For loons prospecting for a territory, playing back the yodel of the resident is a stronger deterrent to landing on the territory than the yodel of a stranger. Further, enhancing territory quality by putting out nest platforms radically alters both the behavior and vocal characteristics of the resident male loon.

Impacts
The finding that Loons change their yodels raises real questions about the use of sound to identify individual birds. Since this 'vocal tagging' technique is increasingly used with endangered species, this research throws doubt on much of that data.

Publications

  • No publications reported this period


Progress 01/01/03 to 12/31/03

Outputs
Using canonical discriminant analysis and measuring the change in Canonical factors, we find that the yearly change of the same loon on the same lake averages about 1 unit. But different loons on different lakes have an average difference of 3.0 units. Thus the yearly change is significantly less than the difference from one loon to another. The surprise is that when a male loon changes lakes either because it displaces another loon or is itself displaced, its yodel changes by an average of 3.0 units. This change may occur in either the first or second year on the new territory. Exactly why this change takes place is not clear. We thought that it might be because in changing lakes a male loon also changes its female partner. When one male displaces another the female remains behind and mates with the new male. To test this idea we looked at situations where the female was displaced and a new female took over a territory while the male remained the same. Under these circumstances the yodel changed an average of 1.28 units, not significantly different from the normal year to year change. Clearly, vocal tagging is not a useful technique for identifying individual loons. All this research is taking place in the context of examining the selection and maintenance of breeding territories in loons. The yodel is an important territorial signal and we have found that it encodes the size of the loon; bigger loons have lower pitched yodels. Further, playing back tape recordings of yodels shows that there is a greater response from resident loons to lower rather than to higher pitched yodels. For loons prospecting for a territory, playing back the yodel of the resident is a stronger deterrent to landing on the territory than the yodel of a stranger. Further, enhancing territory quality by putting out nest platforms radically alters both the behavior and vocal characteristics of the resident male loon.

Impacts
Understanding how loons establish territories and the role of their communication system is likely to be useful for their conservation. Since Loons are a species of special concern in several states, this research is likely to be especially helpful.

Publications

  • No publications reported this period


Progress 01/01/02 to 12/31/02

Outputs
The 'Yodel' call of the Common Loon, Gavia immer, is a territorial signal given only by the male loon. It is also the most complex vocalization that a loon produces. If individual recognition is to be found in any of the loon's vocalizations, the yodel is the most likely place to look. Since loons are threatened in much of the Eastern United States, there is great interest in being able to identify individual loons with the necessity of capturing them and banding them. If the yodel consistently signals a male loon's individuality, 'vocal tagging', recognizing an individual loon by its call, would be feasible. We have been recording and analyzing loon yodels collected from banded populations of loons in Michigan and Wisconsin. By recording yodels from the same male year after year we can measure how stable the yodel is within each year, from year to year and when a loon changes territory. We can also compare the yodels of different loons on adjacent lakes. Using canonical discriminant analysis and measuring the change in components 1 and 2 we find that the yearly change averages about 1 unit. The difference from loon to loon in adjacent lakes averages 3.0 units. Thus the yearly change is significantly less than the difference from one loon to another. The surprise is that when a loon changes lakes either because it displaces another loon or is itself displaced, the yodel changes by an average of 3.0 units. This change may occur in either the first or second year on the new territory. We have no idea why loons should change their yodel when changing territory, but this result means that vocal tagging is not likely to be a useful technique. All this research is taking place in the context of examining the selection and maintenance of breeding territories in loons. The yodel is an important territorial signal and we have found that it encodes the size of the loon; bigger loons have lower pitched yodels. Further, playing back tape recordings of yodels shows that there is a greater response from resident loons to lower rather than to higher pitched yodels. For loons prospecting for a territory, playing back the yodel of the resident is a stronger deterrent to landing on the territory than the yodel of a stranger; we now need to examine whether a lower frequency yodel is more effective than a high pitched one.

Impacts
Understanding how loons establish territories and the role of their communication system is likely to be useful for their conservation. Since Loons are a species of special concern in several states, this research is likely to be especially helpful.

Publications

  • No publications reported this period


Progress 01/01/01 to 12/31/01

Outputs
The 'Yodel' call of the Common Loon, Gavia immer, is a territorial signal given only by the male loon. It is also the most complex vocalization that a loon produces. If individual recognition is to be found in any of the loon's vocalizations, the yodel is the most likely place to look. Since loons are threatened in much of the Eastern United States, there is great interest in being able to identify individual loons with the necessity of capturing them and banding them. If the yodel consistently signals a male loon's individuality, 'vocal tagging', recognizing an individual loon by its call, would be feasible. We have been recording and analyzing loon yodels collected from banded populations of loons in Maine, New Hampshire, Michigan and Wisconsin. It turns out that each population of loons has its own characteristic yodel and that each individual loon's yodel can be recognized and is stable from year to year. However, in 8 cases loons switched territories and in each case the Yodel call changed significantly as well. Why this change occurred is currently being investigated. We are collaborating with Walter Piper in Wisconsin and David Evers in New England to follow the changes in vocalizations that accompany changes in territory. We are also looking at the dispersal of marked young and how their yodels compare both with that of their father and that of the population in which they establish a territory. Finally, we have developed a technique to continuously record the vocalizations of loons all night long using a 4 microphone array. Using computer techniques we can then identify the position of each loon that yodels and recognize which individual it is by its yodel characteristics. This technique will allow us to analyze the use of yodels in vocal communication between different loons. The result of this study will not only be the practical assessment of the feasibility of vocal tagging, but fundamental knowledge of the development and ecological importance of vocal dialects.

Impacts
Understanding how loons establish territories and the role of their communication system is likely to be useful for the conservation. Since Loons are a species of special concern in several states, this research is likely to be especially helpful.

Publications

  • Walcott, C. and David Evers. 2000. Loon Vocal Tagging: An Evaluation of its Feasibility Using a Banded Population of Loons. In McIntyre, J.W. and D.C. Evers (eds.). 2000 Loons: Old history and new findings. Proceedings of a Symposium from the 1997 meeting, American Ornithologists' Union. North American Loon Fund, Holderness, N.H.


Progress 01/01/00 to 12/31/00

Outputs
The 'Yodel' call of the Common Loon, Gavia immer, is a territorial signal given only by the male loon. It is also the most complex vocalization that a loon produces. If individual recognition is to be found in any of the loon's vocalizations, the yodel is the most likely place to look. Since loons are threatened in much of the Eastern United States, there is great interest in being able to identify individual loons with the necessity of capturing them and banding them. If the yodel consistently signals a male loon's individuality, 'vocal tagging', recognizing an individual loon by its call, would be feasible. We have been recording and analyzing loon yodels collected from banded populations of loons in Maine, New Hampshire, Michigan and Wisconsin. It turns out that each population of loons has its own characteristic yodel and that each individual loon's yodel can be recognized and is stable from year to year. However, in 4 cases loons switched territories and in each case the Yodel call changed significantly as well. We are collaborating with Walter Piper in Wisconsin and David Evers in New England to follow the changes in vocalizations that accompany changes in territory. We are also looking at the dispersal of marked young and how their yodels compare both with that of their father and that of the population in which they establish a territory. Finally, we have developed a technique to continuously record the vocalizations of loons all night long using a 4 microphone array. Using computer techniques we can then identify the position of each loon that yodels and recognize which individual it is by its yodel characteristics. This technique will allow us to analyze the use of yodels in vocal communication between different loons. The result of this study will not only be the practical assessment of the feasibility of vocal tagging, but fundamental knowledge of the development and ecological importance of vocal dialects.

Impacts
Understanding territoriality and the communication system of an endangered bird is likely to be useful for its conservation.

Publications

  • No publications reported this period


Progress 01/01/99 to 12/31/99

Outputs
The 'Yodel' call of the Common Loon, Gavia immer, is a territorial signal given only by the male loon. It is also the most complex vocalization that a loon produces. If individual recognition is to be found in any of the loon's vocalizations, the yodel is the most likely place to look. Since loons are threatened in much of the Eastern United States, there is great interest in being able to identify individual loons with the necessity of capturing them and banding them. If the yodel consistently signals a male loon's individuality, 'vocal tagging', recognizing an individual loon by its call, would be feasible. We have been recording and analyzing loon yodels collected from banded populations of loons in Maine, New Hampshire, Michigan and Wisconsin. It turns out that each population of loons has its own characteristic yodel and that each individual loon's yodel can be recognized and is stable from year to year. However, in 4 cases loons switched territories and in each case the Yodel call changed significantly as well. We are collaborating with Walter Piper in Wisconsin and David Evers in New England to follow the changes in vocalizations that accompany changes in territory. We are also looking at the dispersal of marked young and how their yodels compare both with that of their father and that of the population in which they establish a territory. Finally, we have developed a technique to continuously record the vocalizations of loons all night long using a 4 microphone array. Using computer techniques we can then identify the position of each loon that yodels and recognize which individual it is by its yodel characteristics. This technique will allow us to analyze the use of yodels in vocal communication between different loons. The result of this study will not only be the practical assessment of the feasibility of vocal tagging, but fundamental knowledge of the development and ecological importance of vocal dialects.

Impacts
Understanding territoriality and the communication system of an endangered bird is likely to be useful for its conservation.

Publications

  • Walcott, Charles; David Evers, Michael Froehler and Alan Krakauer, 1999 "Individuality in "Yodel" Calls Recorded from a Banded Population of Common Loons" Bioacoustics 10: 101-114.


Progress 01/01/98 to 12/31/98

Outputs
The 'Yodel' call of the Common Loon, Gavia immer, is a territorial signal given only by the male loon. It is also the most complex vocalization that a loon produces. If individual recognition is to be found in any of the loon's vocalizations, the yodel is the most likely place to look. Since loons are threatened in much of the Eastern United States, there is great interest in being able to identify individual loons with the necessity of capturing them and banding them. If the yodel consistently signals a male loon's individuality, 'vocal tagging', recognizing an individual loon by its call, would be feasible. We have been recording and analyzing loon yodels collected from banded populations of loons in Maine, New Hampshire, Michigan and Wisconsin. It turns out that each population of loons has its own characteristic yodel and that each individual loon's yodel can be recognized and is stable from year to year. We are collaborating with Walter Piper in Wisconsin and David Evers in New England to follow the changes in vocalizations that accompany changes in territory. We are also looking at the dispersal of marked young and how their yodels compare both with that of their father and that of the population in which they establish a territory. Finally, we have developed a technique to continously record the vocalizations of loons all night long using a 4 microphone array. Using computer techniques we can then identify the position of each loon that yodels and recognize which individual it is by its yodel characteristics. This technique will allow us to analyze the use of yodels in vocal communication between different loons. The result of this study will not only be the practical assessment of the feasibility of vocal tagging, but fundamental knowledge of the development and ecological importance of vocal dialects.

Impacts
(N/A)

Publications

  • Walcott 1998 No reportable publications for this period.


Progress 01/01/97 to 12/31/97

Outputs
The "Yodel" call of the Common Loon is a territorial signal. If individual recognition is to be found in any of the loons vocalizations the yodel is the most likely place. Since loons are threatened in the Eastern United States there is great interest in being able to identify individual loons without the necessity of capturing and banding them. If the yodel consistently signals a male loon's individuality "vocal tagging"-recognizing an individual loon by its call would be feasible. To test this idea we recorded the yodels from a banded population of male loons at the Seney National Wildlife Refuge on Michigan's Upper Peninsula and from the Isle Royale National Park. We have analyzed the yodels of 12 loons over a period of 7 years. Using multivariate analysis we can recognize the characteristics of the yodel of each individual loon. The yodels seem to be stable from year to year; the differences between loons are greater than the year to year differences. Year before last we recorded yodels from a loon as it switched its territory. The B-Pool loon was challenged by the male from T2 West. The B-Pool loon was ejected and took up residence on B-Pool North, its yodel changed significantly. The yodel of the T2 male that replaced it also changed to more closely resemble that of the old B-Pool male. In the following year the T-2 loon's yodel also underwent a dramatic change. Despite these changes associated with territory switches, we can differentiate the loon's yodels with an average 93% accuracy.

Impacts
(N/A)

Publications

  • No publications reported this period


Progress 01/01/95 to 12/30/95

Outputs
Populations of Common Loons, Gavia immer, are of concern in many parts of the country. Studies of their basic population biology are hampered by the difficulty of marking individual birds. For years it has been suggested that individual male loons might be recognized by their vocalizations. We have been examining the "Yodels" of a banded population of loons at the Seney National Wildlife Refuge in Michigan's upper peninsula. Using the computer based sound analysis program "Canary" we have been able to characterize the yodels of all 6 banded loons. The yodel of one of these loons can be recognized successfully about 98% of the time. Curiously, the same regression equations fail utterly to distinguish individuals in the loon population in Squam Lake, New Hampshire. An examination of the yodels shows that there are greater differences between yodels in different populations than there are within the same population. Furthermore, there is an East-West gradient in both length and frequency of the yodels; western loons have longer and higher pitched yodels. This means that recognition of individuals can only be done within a local population. It also raises the interesting question of whether the vocalization of a male loon moving from one population to another changes to adapt to that of the new population. Our research shows that "vocal tagging" can be a useful tool for the study of site fidelity in male loons.

Impacts
(N/A)

Publications

  • NO PUBLICATIONS REPORTED THIS PERIOD.


Progress 01/01/94 to 12/30/94

Outputs
Male common loons, Gavia immer, give a series of vocalizations called "yodels" on their breeding territories. We have been studying the yodels of a population of banded male loons at the Seney National Wildlife Refuge in Michigan. An analysis of spectrograms of yodels given by 6 males over a period of 5 years shows that many characteristics of the yodels are the same from year to year. Furthermore, there are clear differences between the yodels of individual males. We have developed an equation to apply to measurements of the yodel that allows us to separate the Seney males with close to 100% success. Surprisingly, this same equation fails to separate the yodels of New Hampshire loons. Nor is it successful with yodels from Isle Royale or Wisconsin. We are investigating the reasons for this failure. The development of a general technique of "voice printing" male loons will permit the identification of individual loons in areas where banding is not possible. This identification will, in turn, make it possible to analyze territory fidelity by male loons.

Impacts
(N/A)

Publications

  • NO PUBLICATIONS REPORTED.


Progress 01/01/93 to 12/30/93

Outputs
Common loons, Gavia immer, give a series of vocalizations called "yodels". These calls are associated with territorial defense and have long been thought to be individually recognizable. David Evers at Whitefish Point Bird Observatory in Michigan has a banded population of loons. Spectrograms of yodel recordings of banded male loons were measured and the measurements compared using multivariate statistics. Clear groupings of the individual loons show that there are characteristics of the call that are associated with individual loons and that are stable from year to year. These results suggest that recording and analyzing loon yodels may be an effective way of recognizing individual loons.

Impacts
(N/A)

Publications

  • NO PUBLICATIONS REPORTED THIS PERIOD.