Organism Biology

Birds have long been considered to have poor senses of smell, but recent studies have shown differential behavioral reactions to various scents in songbirds. Predator detection via olfaction may be particularly important in cavity nesters because predators could trap them or ambush them from within the cavity. We examined the response of House Wrens (Troglodytes aedon), a common, cavity-nesting songbird, to a predator scent. A previous study found that wrens did not respond during the nestling feeding stage, and we hypothesized that the wrens may show anti-predatory behaviors in relation to their investment in the offspring. Specifically, we predicted that wrens may be more hesitant during the incubation stage than the nestling feeding stage. To test this, we placed filter papers treated with urine from the American mink (Neovison vison); a pureed solution of garlic mustard (Alliaria petiolata), an odiferous control; or water in the nest box during both the incubation and feeding stages. We video-recorded the response of the wrens and quantified changes in time to enter the box or time spent in the nest box. Our data showed no significant differences in the reaction of wrens during the incubation stage; during the feeding stage however, there was a decrease in the longest visit to the box in order from the garlic scent, the mink scent, to the water control. Our results indicate that although wrens may not use olfaction to avoid predators, they do modify their behavior in the presence of certain smells.