Biology ETDs

Publication Date

9-26-1975

Abstract

Six territories of Williamson's Sapsuckers (Sphyrapicus thyroideus) and eight of Red-naped Sapsuckers (S. varius nuchalis) were mapped and sampled with a line-strip vegetation sampling technique; these data were subjected to discriminant function and 1·rinciple components analyses to investigate similarities and differences letween territories of the two species.

Interspecific overlap in territorial characteristics is great; differences occur primarily in the number of dead trees, and to a lesser extent in the degree of clumping of aspens (Populus tremuloides); S. Thyroideus tends to nest in areas where aspens are more clumped.

Experiments with playbacks of tape-recordings of calls and drums of the two species indicate that S. thyroideus is interspecifically more aggressive than S. varius; dominance in all aggressive encounters observed supports this conclusion. Interspecific and intraspecific mechanisms of agonistic interactions are the same within each species, but there are distinct differences between the species. Feeding observations indicate that competition for plant food is low and probably is not an important factor in the interspecific territoriality observed. Circumstantial evidence indicates the possibility of competition for nest sites.

Language

English

Document Type

Thesis

Degree Name

Biology

Level of Degree

Masters

Department Name

UNM Biology Department

First Committee Member (Chair)

J. David Ligon

Second Committee Member

Loren David Potter

Third Committee Member

Clifford Smeed Crawford

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