Eastern Bluebirds (Sialia sialis) do not avoid nest cavities containing predator odors

• Published in: The Wilson journal of ornithology Vol. 131; no. 3; pp. 680 - 686
• Main Authors: Stanback, Mark T., Dove, Cameron M., Fonda, Christina, Parkes, Presley, Ptaschinski, Jenna
• Format: Journal Article
• Language: English
• Published: Fort Collins Wilson Ornithological Society 01.09.2019
• Subjects: Animal behavior; Bedding; Birds; Cages; Cardboard; Cavities; Eastern Bluebird; Ecology; Interspecific relationships; Mus musculus; Nest boxes; Nesting; Nests; Odor; Odors; Odour; Olfaction; olfactory; olfato; Ornithology; Peperomia serpens; Predation; Predators; Probability theory; Procyon lotor; SHORT COMMUNICATIONS; Sialia sialis; Soils; Urine; Vinegar; Visual stimuli; Zoology
• ISSN: 1559-4491; 1938-5447
• DOI: 10.1676/18-163

We tested whether Eastern Bluebirds (Sialia sialis) avoid nest cavities containing the odors of potential nest predators: the northern raccoon (Procyon lotor) and the house mouse (Mus musculus). In our first experiment, we applied either raccoon urine or white vinegar to partially completed bluebird nests and recorded whether the bluebirds continued nesting or switched to an empty nest box 10 m away. We restricted our analyses to cases in which the nest start was no more than 50% complete at the time we applied the odor. We found no difference in the propensity of bluebirds to switch nest sites in response to urine versus vinegar. Indeed, the vast majority of bluebirds continued nesting in the box into which we added an odor, suggesting that either bluebirds do not associate the odor of raccoon urine with a significantly increased probability of nest predation or that they perceive a nest box 10 m away as being no less threatened. In our second experiment, we presented bluebirds with a choice of 2 identical nest boxes, one containing clean (unused) mouse cage bedding and the other containing bedding soiled with mouse urine and feces. We concealed the bedding in both treatments under cardboard discs to eliminate visual cues and to force bluebirds to rely on their olfactory abilities. Although we used different volumes of cage bedding in the 2 summers, we found no difference between years in the propensity to avoid soiled bedding: bluebirds showed no sign of avoiding soiled bedding at all.