Repertoire size and phrase variation in the song of the Bell’s Vireo (Vireo bellii) in southern Indiana. Zuzana Kocsisova and Dr. Donald L. Batema

Environmental Science Program, University of Evansville, Evansville, IN 47722

LITERATURE CITED BirdFellow Corporation. 2012. Bell’s Vireo. BirdFellow Social Field Guide. <http://www.birdfellow.com/birds/bells-

vireo-vireo-bellii>

Brown, B. T. 1993. Bell’s Vireo (Vireo belli). Birds of North America. No. 35. Ed. A. Poole and F. Gill. The Academy

of Science, Philadelphia, and The American Orinthologists Union, Washington, D.C.

Budnik, J. M., M. R. Ryan, and F.R. Thompson III. 2000. Demography of Bell’s Vireos in Missouri Grassland-Shrub

Habitats. The Auk Vol. 117 (4) pg 925-935.

Budnik, J. M., M. R. Ryan, and F.R. Thompson III. 2002. Effect of Habitat Characteristics on the Probability of

parasitism and predation of Bell’s Vireo’s nests. Journal of Wildlife Management. Vol 66(1) pg 232-239.

Hands, H. M., R.D. Drobney, M. R. Ryan. 1989. Status of the Bell’s Vireo in the Northcentral United States. Missouri

Cooperative Fish and Wildlife Research unit. U.S. Fish and Wildlife Service.

Hartshorne, Charles. 1973. Born to Sing. Indiana University Press. Bloomington

Kroodsma, Donald. 2005. The Singing Life of Birds. Houghton Mifflin. Boston and New York. 482 pp.

Nice, M. M. 1929. The Fortunes of a Pair of Bell Vireos. The Condor, Vol. 31, No. 1, pp. 13-18.

University of California Press on behalf of the Cooper Ornithological Society.

Nolan, V. Jr. 1960. Breeding Behavior of the Bell Vireo in Southern Indiana. The Condor, Vol 62, No. 4, pp. 225-

244. University of California Press on behalf of the Cooper Ornithological Society.

Pitelka, F. A. and E. J. Koestner. 1942. Breeding Behavior of Bell’s Vireo in Illinois. The Wilson Bulletin, Vol.

54, No. 2, pp. 97-106. Wilson Ornithological Society. http://www.jstor.org/stable/4157121

Sauer, J.R., J.E. Hines, and J. Fallon. 2001. The North American Breeding Bird Survey: Results and Analysis 1966-

2000. Version 2001.2. <www.mbr-pwrc.usgs.gov/bbs/bbs/html>

Scott, Thomas A., P. Y. Lee, G.C. Greene, and D. A. McCallum. 2005. Singing Rate and Detection Probability: An

Example from the Least Bell’s Vireo (Vireo belli pusillus). USDA Forest Service Gen. Tech. Rep. PSW-GTR-

191.

Stang, David. 2012. Vireo bellii (Bell's greenlet). ZipcodeZOO. <http://zipcodezoo.com/Animals/V/Vireo_bellii/>

RESULTS AND DISCUSSION

Phrase Length and Rate

In one 38 min recording with 277 phrases, the average phrase length

was x ̄ = 1.373s ±0.161s (s.d.), which is similar to the reported range of 1.5-

3.0s for this species (Nice 1929, Pitelka and Koestner 1942).

This bird spent 16.2% of the time actively singing, averaging 7.289

phrases per minute, which falls within the previously reported rate of 5-20

phrases per minute (Nice 1929, Pitelka and Koestner 1942, Nolan 1968).

Nolan (1968) noted that singing rate decreased as the season

progressed (from 15 to 5 songs per minute). Our lower rates are from birds in

July when it is expected that singing rate would decline.

Phrase Types

We found more distinct and highly stereotyped phrase types for the

Midwestern subspecies in Indiana (25) than in birds in Oklahoma (4) or

California (10) (Nice 1929, Scott et al. 2005).

We also found that the classic description of the Bell’s vireo song with

an alternating upslur/downslur ending is overly simplified, as there were also

overslurred types of syllables present in our recordings and the non-final

syllables also showed variation (Figures 4-6).

We were also able to begin to look at temporal and spatial variation in

phrase types, finding examples of the same phrase type sung by birds on

different days and in different locales (Figures 5 and 6)

Phrase Variation and Syntax

We also examined variability in the Bell’s vireo song sequence, and

note it contained runs of the same phrase type (30+) before switching to other

phrase types (Figure 7). The song consisted of an unpredictable pattern of

phrase types from the bird’s repertoire (Figure 7).

We did not have enough syntactical data to place the Bell’s vireo into a

group based on song patterns.

No evidence was observed for a couplet pattern like the one suggested

by Brown (1993), Stang (2012), or Birdfellow (2012), since long strings of

the same phrase type occurred without any variation in the end syllable.

INTRODUCTION Male passerines sing to defend a territory and attract a mate. Females,

in turn, often select a mate based on the quality of song and the male’s

repertoire. A study of song, including repertoire size and variability, can

provide insights into breeding success, and is especially important for birds

experiencing population declines (Kroodsma 2005). The Bell’s vireo is one

of many passerine birds that are showing population declines within its range

(Figure 1), especially for the ‘least’ subspecies (Sauer, et.al. 2001). Recent

research on the Bell’s vireo (Figures 2 and 3) has focused on habitat

requirements, breeding biology, and nest parasitism (Hands et al. 1989,

Budnik et. al. 2000, 2002), but little attention has been given to singing

behavior (Scott, et. al 2005), and how it might influence breeding success.

We initiated a study of the Bell’s vireo in southern Indiana to document its

repertoire size and variability in its song.

METHODS We recorded unbanded individuals at The Bluegrass Fish and Wildlife

Area (BGFWA) in Warrick County (N=6) and at Vectren Conservation Park

(VCP) in Gibson County (N=1). A total of 6.2 hours of active song

recordings were obtained over 55 hours during a 10 week period between

June 1 and August 10, 2011. Our recording equipment included a Marantz

PMD 661 digital recorder, Stennheiser ME62 omnidirectional microphone

with a K6 power supply, mounted in a Telinga Universal Pro parabola. To

identify syllables, phrases, and phrase types, sound spectrograms were

visualized using Raven Pro 1.3 software.

Figure 1: Range Map of Bell’s Vireos. Red -

Summer, Blue - Winter, Yellow - Migration,

Purple - Year-Round. (BirdFellow 2012,

Image by Paul Lehman 2009)

Figure 2: Bell’s vireo singing from perch

in typical shrubby habitat. (Photo by

David Oakley)

Figure 3: Bell’s vireo is characterized by faint wing bars and spectacled head pattern;

grayish above and white below, with light yellow on sides (Photo by Ron Howard).

Figure 7: Representations of a song sequence; each phrase type is identified by a different

color.

Figure 4: Two distinct phrase types of a Bell’s Vireo (BGFWA). Note similarity,

especially in end syllable.

Figure 5: Three phrases of a single Bell’s Vireo (BGFWA) for different dates: June 2,

June 26, and July 7.

Figure 6: Two phrases of a Bell’s Vireo. Top: VCP July 19. Bottom: BGFWA July 7. Note

syllable similarity in phrases for different individuals. Band at ~6kHz is noise from

crickets.

CONCLUSION Our results show that there is more complexity to the song of the Bell’s

vireo than previously thought. However, further study is needed to identify

the development of the song and the meaning of the observed pattern, and to

explore variation in the song of the Bell’s vireo based on location, breeding

status, time of year, and individual variation. As suggested by McCallum

(personal communication), longer recordings may help us better understand

the song syntax of this declining species.

ACKNOWLEDGEMENTS I would like to thank Dr. Batema for his help and guidance throughout this project,

NOAA (grant SEC-OED-2009-2001847) for the funding, and Dr. Batema and Dr. Gordon

for feedback on earlier drafts of this poster.