Undergraduate Honors Thesis


The Distribution of Barn Swallow (Hirundo rustica) Nest Height in Boulder County and Its Effect on Nest Temperature and Reproductive Success Public Deposited

  • Nest site selection is an important part of reproduction in birds. Nest location can affect the outcome of reproductive attempts, such as nest microclimate or nest predation. In some species, the choice of nest location has more constraints than others due to the availability of suitable habitat. In barn swallows (Hirundo rustica) nest choice is highly constrained by their use of human structures to build nests. One of these constraints is their nest height, which has been found to affect outcomes in other passerine species. In this study, I assessed the extent to which barn swallow nests vary in height, how environmental factors correlate with height, and whether this variation affects their reproductive outcomes. I measured the heights of 135 active and 76 inactive barn swallow nests at 26 sites in Boulder County and determined reproductive outcomes for active nests through nest monitoring. Mean nest height was 3.1 ± 0.7m and the overall range was between 1.9 and 4.1 meters tall. No difference between the height of active and inactive nests was found. Height was associated with nest site. Environmentally, nest height was not correlated with nest temperature. Despite variation in height, no difference in reproductive outcomes based on nest height were found. Additionally, no difference in causes of nest failure, including predation, were associated with height. This finding may indicate that barn swallows are adapted to a broad range of heights in Boulder County. Nest features beyond height may be more influential on nest choice. Further research into height variation in other locations across barn swallows’ wide range may reveal trends based on broader geographic factors.

Date Awarded
  • 2023-03-16
Academic Affiliation
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Granting Institution
Last Modified
  • 2023-04-18
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