Results

Influence of body mass on respiratory parameters

As penguins grew and gained weight, their breathing patterns changed:

  • Expiratory and inspiratory flow increased significantly with body mass
  • Expiratory and inspiratory tidal volume increased significantly with body mass
  • Breath duration increased significantly with body mass
  • Respiratory frequency decreased significantly with body mass
Figure 1. Relationship of respiratory parameters and body mass. All respiratory parameters and body mass have been log10-transformed.

Age-related variation in respiratory parameters

When I compared younger adults (around 2 years) to older penguins (24+ years), the older birds showed:

  • Significantly longer breath durations
  • Significantly lower respiratory frequency
Figure 2. Relationship of respiratory parameters and age. All respiratory parameters have been log10-transformed.

We can see why when we look at their specific breathing patterns:

  • Older penguins showed distinct breath-hold periods after inhalation, during which airflow dropped to zero and lung volume remained at its peak until the next expiration.
  • Younger adults and chicks, by contrast, maintained a continuous breathing cycle with no pauses.
Figure 3. Respiratory tracings showing the normal breathing pattern in an adult (left) and in a 2-year-old adult/chick (right). The blue line represents respiratory flow, while the pink line represents volume.
Material & methods
Discussion