Ursidae: The Undergraduate Research Journal at the University of Northern Colorado


Anne Rose

Faculty Sponsor

Xuan Mai Phan


Many animals adjust their signaling patterns throughout the year. Birds may use different signals as they increase association with mates and expend more energy in territory defense. Song is typically associated with territorial defense and pair bonding between mates, while calls often relate to maintaining contact between foraging birds. We studied variations in vocal behavior in canyon wrens (Catherpes mexicanus) by recording a pair across the midwinter-early spring transition preceding nesting. Recordings were made at the same time weekly for ten weeks. Call rate decreased during this period, contrasting strongly with increasing song production. The occurrence of low frequency vocalizations following songs also increased, which may serve as an aggressive signal in territory defense. Behavior observations coupled with the recording results indicate that canyon wrens alter their vocal communication with the shift into the breeding season. These changes likely correlate with increased need for strong partnership and territorial resources.