Selecting a nest site is an important decision for waterfowl. Because most nest failure is due to depredation, the primary selective pressure in choosing a nest site should be to reduce depredation risk. This task is difficult because predators use differing tactics to locate nests, such as olfactory or visual cues. I investigated several components of waterfowl nest-site selection and success on sites with shelterbelts (planted tree-rows) in North Dakota, during the 2006 and 2007 nesting seasons. I found that meteorological conditions impacted nest depredation; artificial nests were more likely to be depredated when either temperature or dew point was high. These meteorological conditions should improve foraging efficiency for olfactory predators by increasing odor concentration. Waterfowl selected nesting sites with greater visual concealment than random locations (lateral concealment). However, the only difference found between successful and depredated nests was lateral dispersion, an olfactory concealment characteristic. Nest density was higher in areas without shelterbelts than in areas near shelterbelts. Nest success for waterfowl decreased as shelterbelt height increased. Other shelterbelt characteristics, like porosity and orientation, did not affect nest success or nest density. Given that nest predators differ in foraging habitat, temporal patterns of activity, and searching modalities, nest site characteristics that conceal the nest from 1 predator species may increase its vulnerability to another predator. For instance, risk due to olfactory predators should be reduced near shelterbelts because locating nests would be more difficult as turbulence is generated by the shelterbelts. Concomitantly, shelterbelts could also increase the presence of visual predators, by providing nesting sites and vantage points. In my study, any benefits shelterbelts provide in reducing nest depredation by olfactory predators may have been offset by increasing nest depredation from visual predators. Hence nesting near shelterbelts was neither a liability nor a benefit to ducks.
| Identifer | oai:union.ndltd.org:UTAHS/oai:digitalcommons.usu.edu:etd-1042 |
| Date | 01 December 2008 |
| Creators | Borgo, Jennifer |
| Publisher | DigitalCommons@USU |
| Source Sets | Utah State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | All Graduate Theses and Dissertations |
| Rights | Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact Andrew Wesolek (andrew.wesolek@usu.edu). |
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