Energetics of diving in macaroni penguins

Area of Science:

• Marine biology
• Animal physiology
• Avian diving behavior

Background:

• Diving birds exhibit complex physiological adjustments to manage oxygen during foraging.
• Macaroni penguins display unique diving behaviors that warrant investigation into their underlying physiology.

Purpose of the Study:

• To investigate the physiological adjustments of macaroni penguins during diving.
• To estimate oxygen consumption rates and determine if dives are within the aerobic dive limit (cADL).
• To explore the role of heart rate and abdominal temperature in regulating dive duration.

Main Methods:

• Measured heart rate (fH), abdominal temperature (T(ab)), and diving depth in 13 free-ranging female macaroni penguins.
• Estimated mass-specific oxygen consumption (V(O(2))) based on measured physiological variables.
• Analyzed the relationship between physiological parameters, dive duration, and dive bout characteristics.

Main Results:

• Heart rate and other measured variables accounted for 36% of the variation in dive duration.
• Over 95% of dives were within the calculated aerobic dive limit (cADL) when V(O(2)) was estimated.
• Abdominal temperature declined during diving bouts, with a mean decrease of 2.32°C, but this did not correlate with increased dive duration.

Conclusions:

• Macaroni penguins largely dive within their physiological aerobic capacity.
• While abdominal temperature decreases during prolonged diving, it doesn't appear to be the primary factor limiting dive duration.
• Other unmeasured factors likely play a more significant role in determining dive and dive bout durations in this species.