The Olive-sided Flycatcher (Contopus cooperi) is a medium-sized insectivorous bird that breeds in coniferous forests across North America. Like many other flycatcher species, the Olive-sided Flycatcher is known for its distinctive vocalizations. The bird’s most recognizable call is described as a loud, three-part “quick, three-BEERS!” The “quick” part is sometimes repeated up to four times, while the “beers” is strongly accented. This Call Note functions as the Olive-sided Flycatcher’s advertising call and helps the bird establish its breeding territory. In this article, we will explore the characteristics and contexts of the Olive-sided Flycatcher’s vocalizations in more detail.
Description of the Olive-sided Flycatcher’s Call
The Olive-sided Flycatcher’s Call Note consists of three parts:
– The introductory “quicks” – These are short, sharp, loud whistles that are repeated up to four times. The pitch of the quicks rises slightly with each repetition.
– The pause – A brief pause follows the introductory quicks. This pause separates the quicks from the third part of the call.
– The “beers” – This is a loud, strongly accented three-syllable phrase sounding like “bee-EERS.” The first syllable starts low and rises sharply in pitch on the emphasized second syllable before dropping again on the third.
This three-part call is often described as sounding like “quick, quick, quick, quick, … three BEERS!” The entire call lasts about one second when all parts are included. The Olive-sided Flycatcher may repeat this call multiple times in succession while perched high atop a tree.
Audio of the Olive-sided Flycatcher’s Call
Here is an audio clip of the typical Olive-sided Flycatcher call:
[insert audio clip]
As you can hear, the call carries far and has a sharp, urgent quality that really cuts through the forest environment. The emphatic “BEERS!” at the end is what gives this species its name among birders. Next, let’s look at when and why Olive-sided Flycatchers make this distinctive call.
Context and Purpose of the Call
The Olive-sided Flycatcher’s Call Note serves multiple purposes:
Territory Defense
The Call Note is used primarily by male Olive-sided Flycatchers to defend their breeding territories. The birds establish territories after returning from migration in spring. The prominent calls proclaim that a territory is occupied. Neighboring males often give answering call notes to delineate territory boundaries. Frequent calling continues through the breeding season and helps the birds maintain their territories.
Attracting a Mate
The far-carrying Call Note serves to attract females to the male’s territory for mating. Unmated males call more frequently to advertise their availability and fitness. The urgent quality and repetition of the call makes it attention-grabbing and may reflect the male’s level of excitement. Females can likely discern details about individual males based on characteristics of their calls.
Staying in Contact
Mated pairs may also use the Call Note to maintain contact with each other within their territory. This helps coordinate activities like nesting and foraging. Pairs sometimes perform a quieter version of the call and may give answering calls.
Alarm
In addition to the main Call Note, Olive-sided Flycatchers have a harsh single-part alarm call they give to signal danger or when disturbed. This call sounds like a loud, descending “pip.” They may combine the pip with their Call Note when highly agitated. The alarm call alerts others to potential predators.
When Olive-sided Flycatchers Call
Olive-sided Flycatchers are most vocal early in the breeding season from late May through mid-June. Calling is most intense when they first arrive back on territory and are establishing nest sites.
Males call persistently throughout the day, but peak calling occurs in the early morning and evening. Fewer calls are given at midday and overnight when less active. However, males may call overnight during the height of the breeding season to deter intruders and attract additional mates.
Cool and wet weather may suppress calling activity somewhat, while warm and calm conditions tend to increase vocal activity. However, males call consistently whenever present on their territory through the summer months. Migration in the fall brings an end to the Olive-sided Flycatcher’s characteristic vocalizations until the next breeding season.
Variation in the Call
While the basic pattern of the Olive-sided Flycatcher’s Call Note remains the same, individual birds show some variation in the details:
– Number of introductory “quicks” – This varies from one to four notes with three being typical. Some regional dialects may differ slightly in the usual number given.
– Speed and pitch – Some birds deliver the call rapid-fire while others space it out more. The pitch may range from very high and urgent in young males to lower and more deliberate in older birds. Regional variations in pitch and speed also exist.
– Accent pattern – Subtle differences occur in which syllables receive the greatest emphasis, with some individuals stressing the first “beer” and others emphasizing the final syllable.
– Volume – Call volume is adjusted based on distance to the receiver and level of excitement. Soft contact calls are given to mates while loud calls carry over longer distances.
So while the fundamental pattern remains consistent, individual and regional variations in the Olive-sided Flycatcher’s vocalizations likely communicate important information. Context, behavior, and slight call differences help convey the signaler’s intent and identity.
How the Olive-sided Flycatcher Makes Its Call
Like other birds, Olive-sided Flycatchers have a uniquely modified voice box called a syrinx that enables them to produce intricate calls. The syrinx is located where the trachea branches to send air to the lungs. It contains vibrating tissues and muscles that control pitch and volume.
To generate its Call Note, an Olive-sided Flycatcher uses specialized syringeal muscles to modify the flow of air through the trachea into two sound sources. It controls the membrane tension and aperture of the sound sources to create the whistle-like introductory quicks.
Next, it pauses before rapidly contracting additional membranes and intrinsic syringeal muscles to produce the louder, sharply rising slurred “BEERS!” This final phrase involves precisely coordinated modulation of both sound sources to accentuate certain syllables.
Fine control of the syrinx coupled with respiration allows the Olive-sided Flycatcher to create nuanced vocal signals full of information. The unique Call Note stands out to communicate ownership of a territory and attract a suitable mate.
Regional Dialects
As mentioned, subtle differences in the Olive-sided Flycatcher’s Call Note exist across their breeding range based on regional dialects:
Pacific Northwest
In Washington, Oregon, and British Columbia, the Call Note averages lower in pitch compared to other regions. It also has a slower, more deliberate pace with extended pausing between the introductory quicks and final phrase. Four quicks are often given.
California and Nevada
In these states, the Call Note tends to be higher-pitched, more clipped, and hurried-sounding. Only one to two intro quicks are typical. The final “BEERS!” is loud with maximum emphasis on the first syllable.
Rocky Mountains and Southwest
Flycatchers in this region give an intermediate Call Note in terms of speed and pitch. It often starts with three quicks and has a more evenly accented “BEERS!”
Eastern Provinces
In contrast to the western dialect regions, Ontario, Quebec, and the Maritimes feature a Call Note with a slightly descending pitch. The introductory quicks are wavering whistles instead of straight.
Significance of Dialects
The existence of different Olive-sided Flycatcher dialects across their range shows regional cultural evolution. Young birds likely learn the local version of the call from adults breeding in a given area. Dialects help birds identify which region rivals are from during territorial interactions. Females also prefer the local dialect of their natal region when selecting a mate.
Use of Call Notes by Other Bird Species
The Olive-sided Flycatcher’s far-carrying Call Note makes it vulnerable to mimicry by predatory bird species. Both the Gray Jay and Northern Shrike occasionally give imitations of the Olive-sided Flycatcher’s call in an attempt to lure them within striking distance.
By mimicking the call, these predatory birds try to fool flycatchers into approaching what seems like an encroaching territorial rival. However, Olive-sided Flycatchers usually give alarm calls and avoid approaching when they detect the ruse. Slight differences in call tone, rhythm, and behavior from their own species tip them off.
In contrast, a few other forest songbirds have evolved remarkably accurate imitations of the Olive-sided Flycatcher call. These include species like the Blue-headed Vireo, Black-capped Chickadee, and Red-eyed Vireo. However, their mimicry functions very differently. These species copy the call into their own vocal repertoires and sing imitations during their musical solos to showcase vocal skill rather than exploit flycatchers.
Conclusion
In summary, the Olive-sided Flycatcher’s far-carrying Call Note – “quick, quick, quick, quick, … three BEERS!” – plays an essential role in territory defense, mate attraction, and coordination between pairs in this migratory songbird species. Regional variations in the call reflect cultural evolution across the species’ breeding range. Imitation of this signature Call Note by other bird species illustrates both its vulnerability for exploitation by predators and value as a conspicuous signal of territoriality and fitness demonstrating vocal mastery. The next time you find yourself in North American coniferous forests from spring through summer, listen for this distinctive vocalization ringing through the trees as Olive-sided Flycatchers settle in for the breeding season.
