What's in a quack? Analyses of full repertoire of duck vocalizations and effects of vocalizations on conspecific physiology

Why this research is being done

Ducks have 19 distinctly different types of vocalizations based upon environmental and social context and these vocalizations have differential impacts on conspecific physiological responses. We wish to understand what information is being relayed by different vocalizations so that we can develop a sensor system to monitor vocalizations to assess flock health and welfare in real time. All of our poultry species are social animals, and this is particularly true for ducks, with vocalizations being a critical component of their interactions. Despite this knowledge of wild Mallards, poultry scientists have yet to take the natural and investable next step to utilize flock vocalizations as indicators of welfare status.

Vocalizations can also be used to determine if an animal is experiencing a specific stimulus. Birds have many species-specific songs and calls. Examples of different types of calls include begging signals, contact calls, migratory flight calls, food calls, and alarm calls. Alarm calls are key antipredator strategies, and different types of alarm calls are categorized by the context in which they are given, and the level or type of predatory threats that exist, but also to some degree by the way they sound. With little research on this topic, a better understanding of the birds’ calls could help us to better understand their welfare and wellbeing, from their point of view. We know from the wild bird literature that birds communicate with each other in various ways, one way being through vocalizations. Since Pekin ducks are domesticated Mallard ducks, we hypothesized that Pekin ducks would have a diverse repertoire that is affected by the sex, social group, and specific stimuli. We chose to work with the Pekin duck as it is the most common commercial breed globally and the duck is the second most common food animal globally.

Results

We characterized the vocal system of the ducks under each stimulus and social treatment in four ways: overall call rates, call diversity, call repertoire, and call spectral properties. We found that Pekin ducks produce up to 16 different vocalizations. Ducks produced the most calls by far when someone was sitting in the chamber with them (30.04 ± 4.45 calls/min). For call diversity, we found that there was a significant main effect of hen number but no main effect of drake number. Our results suggest that Pekin ducks are affected by the types of stimuli and social environment in how much they vocalize and in the properties of the calls they use. In addition, males and females differ somewhat in the repertoire of the calls they use, and in the spectral properties of their calls.

We also tested Pekin ducks with playbacks of 5 different vocalizations plus a no noise and white noise stimulus as our controls (N = 15 ducks/sex/treatment). The “AM long” call is a common vocalization made by both sexes. “Honk” is also produced by both sexes and is thought to be an alarm call. “Pips” and “harmonics” are common vocalizations made only by hens. The “egg laying squiggle” is also only made by hens. Trials consisted of an initial recording in a quiet condition with 5 consecutive measurements of heart rate, blood pressure and respiratory rate. A specific vocalization was then played on repeat while 8 more measurements of blood pressure, heart rate and respiratory rate. Finally, 5 measurements of heart rate and blood pressure were taken post playback along with a final recording of respiratory rate. Data from all blood pressure measurements (systolic, diastolic and mean arterial pressure [MAP]), heart rate (HR) and respiratory rate (RR) were subject to a principal component analysis. Our results showed there was a significant main effect of playback type on the blood pressure of ducks during the playbacks. Ducks experienced an increase in blood pressure when played back the honk vocalization, as well as the white noise control. Our data shows that there are sex differences when it comes to vocalization playbacks in Pekin ducks, but overall, the honk vocalization and white noise control significantly increased ducks’ blood pressure. This study was a critical steppingstone to understand how Pekin duck vocalizations affect conspecific physiology.

Data

Other Pictures

Conclusions
  1. Ducks make specific vocalizations based upon social context and environmental stimuli.
  2. Hens have a larger repertoire of vocalizations than do drakes.
  3. Different vocalizations have different impacts on conspecifics.
Next Steps
  1. More fully determine how all vocalizations impact conspecific physiology and behavior.
  2. Better understand what specific vocalizations ducks produce under specific conditions: heat stress, cold stress, hunger, disease, etc.
  3. Develop sensor system and artificial intelligence to monitor flock vocalizations in real time to determine any potential impacts on production, health or welfare.
Contact information

Gregory S. Fraley gfraley@purdue.edu | Purdue ANSC Directory