Northern Cardinal (Cardinalis cardinalis)
Song: Typical songs consist of a series of slurred, clear whistles, with much variation.
Songs are sometimes followed by a buzzy, lower volume, trill like chrrr that somewhat resembles the trill of a red squirrel (Borror 1961). These chrrr notes are usually added at times of heightened excitement, when males are in close proximity to other cardinals, either male or female (Ritchison 1988).
Northern Cardinal complex song with "chrrrr", February 5, 2011. Engel Conservation Area, Waukesha County, Wisconsin. The male performed the Song-Dance display as it sang during this recording.
At these times they often sing their songs in quick succession, with only short spaces between, and they change song types more frequently as well (Kroodsma 2005), approaching immediate variety mode, in contrast to their usual eventual variety. The chrrr notes act as a bridge between the different song types.
These extra-song chrrr notes may function as a display of the males fitness, as there is some evidence that production of these sounds is particularly difficult (Halkin et al. 1999).
When establishing a pair bond early in the breeding season, singing is sometimes accompanied by the Song-Dance display, in which the male stretches his neck, raises his crest and sways from side to side as he sings to the female (Laskey 1944, Halkin et al. 1999).
Borror, D. J. 1961. Songs of finches (Fringillidae) of eastern North America. Ohio J. Sci. 61:161.
Halkin, Sylvia L. and Susan U. Linville. 1999. Northern Cardinal (Cardinalis cardinalis), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/440 doi:10.2173/bna.440
Kroodsma, Donald. 2005. The Singing Life of Birds. Houghton Mifflin Company, Boston New York.
Laskey, A. R. 1944. A study of the Cardinal in Tennessee. Wilson Bull. 56:27-44.
Ritchison, Gary. 1988. The Singing Behavior of Female Northern Cardinals. The Condor 88:156-159.