The pied-billed grebe (Podilymbus podiceps) is a species of grebe found in wetlands across North America. It is known for its distinct vocalizations, which serve important functions in communication, pair bonding, and defending territory.
Description of the Pied-Billed Grebe
The pied-billed grebe is a small waterbird, measuring 25–38 cm (10–15 in) in length with a wingspan of 40–58 cm (16–23 in). It has a short, thick neck and a blunt, chicken-like bill, which is white with a broad black band around the middle giving rise to its common name. Its plumage is brownish on the back and flanks, while the underparts are white. The head is accentuated by a black cap and dark patches behind the eyes. Males and females look identical. Juveniles have stripes and blotches of color rather than solid patches.
This species occurs year-round in marshes, ponds, lakes, and other wetlands. It dives to capture small fish, crustaceans, and aquatic insects. Courtship begins in April, nesting starts in May or June, and broods of 5–7 chicks hatch in June and July. The nest is a floating platform anchored to emergent vegetation.
Primary Vocalizations
The pied-billed grebe has a repertoire of around 13 distinct vocalizations that communicate different messages.
Advertising call
The advertising call, heard most frequently during the breeding season, is a loud, rhythmic call that sounds like “kloow-kloow-kloow-kloow”. It is repeated steadily for long periods and carries up to 0.8 km over water. This serves to attract mates and establish breeding territories. Both sexes vocalize, though the male’s call is lower-pitched.
Whine call
A high-pitched whining “peee-oh” call is produced by unmated males to attract females. It may also signal distress.
Duet call
Once a pair bond has formed, mated birds perform a duet call, with the male and female alternating their advertising calls rapidly. This duetting helps maintain the pair bond.
Growl call
A short, low-pitched guttural call that sounds like “raaah” is produced by both sexes during aggressive encounters, as a threat display towards intruders in the territory.
Wail call
A loud wailing call is made when the nest or young are threatened. This alert call prepares the chicks to take cover or initiates mobbing behavior against predators.
Call Type | Description | Context |
---|---|---|
Advertising call | Rhythmic “kloow-kloow-kloow” | Attract mates, establish territory |
Whine call | High-pitched “peee-oh” | Attract females, signal distress |
Duet call | Alternating male and female advertising calls | Maintain pair bond |
Growl call | Guttural “raaah” | Threat display against intruders |
Wail call | Loud wailing | Alert chicks to danger |
Nonvocal Sounds
In addition to its vocalizations, the pied-billed grebe produces nonvocal sounds by slapping the water surface with its feet or wings. These sounds signal alarm and communicate within pairs and families.
Foot-slapping
Grebes splash the water surface repeatedly with their large lobed feet when alarmed. This creates loud popping sounds, warning others of danger. It is often performed in synchrony by paired or grouped birds.
Wing-flapping
Grebes may slap the water violently with one or both wings when deterring intruders. The resulting noise and spray provide a dramatic threat display. Wing-flapping also occurs between paired birds or parents and young, serving to maintain contact.
Context and Meaning of Vocalizations
The pied-billed grebe’s vocal repertoire allows complex communication. Call characteristics and context encode specific meanings.
Individuality in calls
The advertising call contains individual differences that grebes likely use to distinguish mates and offspring. The rhythm and pitch of call notes varies by individual.
Duetting in pairs
Duetting plays an important role in acoustic communication between mates. The precisely coordinated calling reflects the close bond between paired birds.
Signaling alarm
Alarm calls like the wail and nonvocal sounds elicit panic responses in chicks. This demonstrates that the sounds convey a specific meaning associated with imminent danger.
Status in territory defense
Low-pitched growls indicate the caller is likely to escalate aggression and attack intruders. Higher whimper calls signal non-threatening status.
Evolution of Vocal Behavior
The pied-billed grebe’s elaborate vocal repertoire provides advantages for survival and reproduction. Selection likely favored the evolution of complex communication in this species.
Increased mating success
Advertising calls allow grebes to attract mates from greater distances across water. Call variation also aids assessment of potential partners.
Improved parental care
Parents and chicks staying in acoustic contact reduces separation anxiety. Alarm calls enable quicker responses to danger by offspring.
Defense of resources
Status signaling through differentiated threat calls minimizes risky fights. Vocal displays also repel competitors without physical contact.
Group anti-predator benefits
Synchronized foot-slapping propagates alarm rapidly. This cooperative behavior enhances predator detection and deterrence.
Conclusion
In summary, the pied-billed grebe has an extensive vocal repertoire comprised of advertising calls, duets, alarm/alert calls, threat vocalizations, and nonvocal sounds. These varied vocalizations support communication between mates, offspring, and group members in the contexts of territoriality, pair bonding, and responding to threats. The grebe’s vocal behavior likely evolved through natural and sexual selection to increase reproductive success and survival through enhanced parental care, resource competition, anti-predator benefits, and mate attraction.