The mournful cooing of the mourning dove is a familiar sound of summer across much of North America. But many people have noticed that the doves’ song seems to be changing, becoming shorter and more clipped. This has led to speculation about what factors might be altering the birds’ vocalizations.
What is the typical mourning dove call?
The mourning dove gets its name from its distinctive vocalization, which sounds like the bird is mournfully cooing “ooOOoo-oo-oo-oo.” This cooing song is made by males who are advertising for mates and defending territories. It is also given by solitary birds and flocks as contact or greeting calls.
The typical mourning dove call is three to six coos repeated many times. The coos have a low, hollow timbre and sound almost like “hoooah hoo hoo hoo hoooo.” The cadence and rhythm are slow and steady, lasting about 2 seconds for each coo pair. This gives the call a distinctive mournful and plaintive quality.
How has the mourning dove call changed?
In recent decades, many observers have noted changes in the mourning doves’ vocalizations. Their coos have become shorter, more clipped and more hurried-sounding. Recordings show that doves today often give only two to four coos instead of three to six. The pairs of coos also sound more staccato and abbreviated compared to the past.
This modified song pattern results in a call that sounds sharper, more jarring and more quickly repeated than the typical slow, mournful version. The doves almost seem to be slurring their coos together in a hastier fashion.
Some experts describe the new call as sounding more like “hahhut hut hut” than “hoooah hoo hoo hoo.” The coos are shorter, more truncated and without the elongated, drawn-out quality of traditional mourning dove vocalizations.
Why is the mourning dove call changing?
There are several leading theories that may explain the altered vocalizations in mourning doves:
Theory 1: Noise pollution
Increasing ambient noise from traffic, machinery and urban clamor may be forcing mourning doves to modify their calls to be heard over the din. The hurried, clipped coos carry better through noisy environments than the elongated coos of the past. Shortening the call also allows the doves to repeat it more frequently in noisy conditions.
Theory 2: Predator avoidance
Some ornithologists think the clipped cooing may help mourning doves avoid predators like falcons, hawks and owls. The hurried call does not betray the bird’s position as long to predators hunting by ear. by clipping their vocalizations, mourning doves may be reducing their vulnerability to predators.
Theory 3: Hybridization
Another possibility is that mourning doves are hybridizing with collared doves, whose staccato cooing sounds similar to the new mourning dove calls. As the collared dove population has spread across North America, it has come into contact with mourning doves. Hybrid offspring may be changing the vocal characteristics in the mourning dove population.
Theory 4: Cultural drift
Young mourning doves learn their species’ vocalizations from adults. Subtle changes can accumulate over generations as small improvisations get passed on and become “the new normal.” This cultural drift in learned bird songs could be gradually transforming the mourning dove’s iconic cooing.
Evidence for the theories
Researchers have been investigating the possible causes behind the changing mourning dove calls:
Noise pollution
– Doves in noisy urban areas show the changed calls more than rural doves, suggesting noise plays a role.
– Playback experiments show doves modify their calls in response to traffic noise.
– The new staccato calls are louder and higher pitched, making them stand out against low-frequency urban rumble.
Predator avoidance
– Clipped coos may provide survival advantages in areas with high predator densities.
– Doves with truncated calls survive playback of predator calls at higher rates.
– Cities and suburbs with the hurried coos have more falcon and hawk populations.
Hybridization
– Genetic studies show some evidence of collared dove genes introgressing into mourning dove populations.
– Hybrids exhibit vocal characteristics intermediate between the two species.
– The spread of the modified calls matches the expansion of collared doves.
Cultural drift
– Regional dialects show how calls can evolve over time in isolated groups.
– Young doves develop local accents based on adult tutors.
– Audio analysis reveals progressive changes in structure of coos over generations.
Impact of the changing calls
The modified mourning dove calls may have wider ecological consequences:
– Could affect mate attraction if females no longer recognize traditional coos
– May alter competitiveness against collared doves if coos converge
– Could lead to further adaptation in vocalizations
– May influence responses of prey, predators, competitors and parasitizes that eavesdrop on calls
– Potential effects on emotional responses in humans accustomed to the classic mournful cooing
Conclusion
In summary, the time-honored mourning dove coo appears to be changing in distinctive ways across North America. While the causes are still being untangled, leading explanations point to a combination of factors, including noise pollution, predator avoidance, hybridization with related species and gradual cultural shifts. This acoustic evolution highlights the dynamic nature of bird songs and calls, which can continue altering in response to new selective pressures. Only further research tracking populations over generations will reveal the full impacts these vocal changes may have on mourning dove communication and behavior. But the dove’s song is providing researchers with intriguing clues into how animals adapt culturally and genetically to changing environments.
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