Date of Award:

5-1-1976

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Department name when degree awarded

Life Sciences:Biology

Committee Chair(s)

Keith L. Dixon

Committee

Keith L. Dixon

Committee

Allen W. Stokes

Committee

Ivan G. Palmblad

Committee

Dennis J. Martin

Committee

Dennis M. Forsythe

Abstract

Free-living Willets, Catoptrophorus semipalmatus inornatus, were studied during the breeding seasons of 1974 and 1975 in Cache County, Utah. Upon arrival in early April the birds congregated at communal courtship-feeding ponds for 2-3 weeks. They subsequently dispersed to surrounding fields where nesting territories were maintained. The birds began forming flocks in mid-June and all birds had departed by mid-August. A spectrographic analysis is presented for the 10 adult and one chick vocalizations recognized in this study, and a numerical and a biological description is given for each call. The Pill-will-willet flight-song and the accompanying song-flight are discussed in detail. A flight-intention call (Kyah-yah) is shown to vary in signal content in a graded fashion with the number of notes present in the call. The Kleep alarm call is shown to vary in repetition rate directly with the intensity of the alarm response. Mobbing was found to be an important activity during the incubation and fledgling care stages and is discussed in detail. Interspecific group mobbing with Willets and Long-billed Curlews responding to each other's vocalizations is documented (without playback experiments) for the first time in nonpasserines. Precopulatory displays, both visual and acoustic, are related to attack-escape tendencies of the members of a pair. Several visual displays (including wing-up, head-bobbing, and flap-hop) which are common in other Charadrii are described under the vocalizations with which they often are associated. The vocal repertoire of the Willet is discussed in terms of its adaptiveness in an open country habitat. It is suggested that the information of Willet sound signals is encoded primarily in temporal rather than frequency components. The number of functional categories represented in the Willet repertoire seems higher than for other tringines that have been studied spectnographically.

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