Nest building consistency in Yellow Warblers.

Consistency in an individual animal’s behaviour is a curious observation. If an animal shows a consistent behaviour, this suggests that the behaviour is not mediated by immediate environmental cues, and may suggest that the behaviour is heritable to some degree. In the summer of 2008, former Queen’s University undergraduate student Allie Patrick, investigated consistency in nest building behaviours of Yellow Warblers (Dendroica petechia) at the Queen’s University Biological Station (QUBS).

Photo shows two nests constructed by the same individual for eight different female Yellow Warblers. Nests constructed by the same female are arranged vertically. Note the similarity of nests constructed by the same female and the diversity of nests constructed by different females.

It is fascinating to think that the diversity of Yellow Warbler nests and the materials used to construct them is not at all random and that individual females actively seek-out and gather specific materials. This is readily seen in the photos, where one female Yellow Warbler lined her nests almost exclusively using duck feathers (nest pair on far left), while another used fluffy cattail (Typha spp.) pappus (second from the left). Using specific materials is not limited to the nest lining. Some females incorporated pieces of Common Mullein (Verbascum thapsus) leaves (third from the left) throughout the nest cup, and others used almost exclusively dry grasses and bark fibers (fourth from the left). To some degree breeding location will influence the availability of nesting materials; in some locations there may be no Common Mullein, while in others there may be no cattail pappus. However, many of these females nested within the same marsh (and therefore should have had access to similar materials), yet they built distinctive nests. Distinctive nests constructed by females in close proximity to each other suggests that, in addition to location, individual females show a preference for specific materials when constructing their nests.

These eight nests represent a small sample of the diversity of Yellow Warbler nests within the breeding population at QUBS in southeastern Ontario. As seen in the photos, the population-level variation in Yellow Warbler nests is impressive, yet nest building behaviour at the individual level may be much less variable. – Posted by Vanya Rowher


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