The Varied Thrush is a medium-sized North American songbird known for its beautiful song. It is found along the Pacific coast from Alaska to California. The male Varied Thrush sings a loud, ringing song to defend its breeding territory and attract a mate. The song of the Varied Thrush is complex and melodious, consisting of a mix of musical warbling notes and buzzy tones. In this article, we will explore the characteristics of the Varied Thrush’s song, when and where it sings, how the song varies across populations, and the functions of the song.
What does the Varied Thrush’s song sound like?
The most distinctive feature of the Varied Thrush’s song is its far-carrying, bell-like quality. The first part of the song consists of a series of rich, flute-like notes that alternate in pitch. These musical notes have an uplifting, spirited quality that carries through the forest. The opening notes are followed by a more complex jumble of gurgling and buzzing sounds. The Varied Thrush’s song has been described by ornithologists as “a spiral of ethereal, bell-like notes combined with buzzes and gurgling whistles.” It lacks the repetition found in many bird songs, making each song unique. The song begins loud and spirited, trailing off into a softer warbling at the end. When heard from a distance, only the loud, clear opening notes are audible. Up close, the complexity of the song becomes apparent. The rich notes coupled with mechanical sounds give the Varied Thrush’s vocalization an otherworldly quality.
When does the Varied Thrush sing?
The Varied Thrush sings most actively during the late winter and early spring breeding season. In February and March, males sing persistently to proclaim their breeding territories and attract mates. The most vigorous singing occurs during the dawn chorus, when birds are most active. Songs can be heard throughout the day, but singing activity tapers off in the late morning and picks up again in the evening before roosting. As the breeding season progresses into late spring and summer, singing frequency decreases. However, males may still sing sporadically through the summer months while caring for their young. The Varied Thrush does not migrate and maintains its territory year-round. So songs may be heard even during the winter, though not with the same intensity as the breeding season. Surges in singing activity often coincide with periods of warmer weather in the winter months.
Where can you hear the Varied Thrush’s song?
The Varied Thrush breeds in coniferous forests along the Pacific coast. Its voice can be heard in mature stands of spruce, fir, pine, and cedar from Alaska to northern California. It is most abundant in the dense, damp forests found at intermediate elevations in coastal mountain ranges. Some key places to listen for singing Varied Thrushes include:
- Olympic National Park, Washington
- Mount Rainier National Park, Washington
- North Cascades National Park, Washington
- Redwood National and State Parks, California
- Coastal British Columbia
The loud, resonating notes of the Varied Thrush’s song carry well through its mountain forest habitat. Find a quiet spot to stop and listen in one of these forests during spring, and you are likely to hear the distinctive vocalizations echoing through the trees. Dawn is the best time to detect the spirited opening notes that carry far and wide across the landscape.
How does the song vary across populations?
Although Varied Thrush populations across the west coast share the same overall song structure, differences in vocalizations have been noted between some northern and southern subspecies. In one study comparing Alaskan and Californian populations, Alaskan birds were found to sing faster, shorter songs with notes of higher frequency. Meanwhile, California thrushes sang longer songs with more drawn out low-frequency elements. Researchers theorize that the warmer, wetter climate of coastal California allows sounds to transmit more efficiently than the cooler, drier Alaskan interior forest. So California birds can afford longer, slower songs, while Alaskan thrushes must compress their vocalizations to counteract sound attenuation. Additional differences were found between coastal and interior mountain populations in Washington, reflecting local adaptations to habitat acoustics. Further study is needed to determine if vocal variations warrant subspecies recognition. However, it shows the subtle regional diversity within a species’ song.
What are the functions of the Varied Thrush’s song?
The song of the Varied Thrush serves several important functions related to mating and territoriality:
Territory Defense
Male Varied Thrushes sing persistently while perched at the edges of their breeding territories in late winter and early spring. The songs announce occupancy of the territory and serve as a warning to other males. Long, loud songs communicate a willingness to fight off intruders if needed to defend the territory. Frequent singing also provides information on the resident’s condition, discouraging weaker rivals from picking fights they are likely to lose.
Mate Attraction
Female Varied Thrushes listen for singing males as they evaluate potential breeding partners. A male capable of producing elaborate, vigorous songs signals his physical fitness. Receptive females will visit singing males to assess them further through courtship feeding rituals. Effective singing is critical for mating success.
Coordination of Breeding Activities
The dawn chorus of songs stimulates reproductive development in both males and females. It synchronizes readiness for breeding within the population so that most offspring will hatch under favorable conditions. The later decrease in singing indicates the end of the fertile period.
Individual Recognition
Just as human songs contain distinctive elements specific to each singer, Varied Thrush songs vary enough for individual recognition. Both males and females become familiar with their mate’s particular song pattern. This helps males respond appropriately to their mate’s vocalizations and lets pairs reunite after separation.
Conclusion
The Varied Thrush has a remarkable song that is both beautiful and functionally important for its lifestyle. The spirited, flute-like opening notes followed by gurgling and buzzing sounds make it one of the Pacific Northwest’s most easily identifiable bird songs. This vocalization plays a key role in breeding, territoriality, and communication for the species. Next time you are in a coastal forest, stop and listen to the fascinating song of the Varied Thrush echoing through the trees. Pay attention to the intricacies of its warbling notes and you may start to understand why this shy bird is so vocal on its secluded breeding grounds.