Periodic excretion patterns of seabirds in flight

Area of Science:

• Marine Ecology
• Avian Biology
• Oceanography

Background:

• Seabird excretion at sea is poorly understood, limiting evaluation of their ecosystem influence.
• Nutrient redistribution by marine animals, like the 'whale pump,' highlights the importance of excretion studies.
• Current knowledge of seabird excretion is primarily from terrestrial environments.

Purpose of the Study:

• To investigate the excretion behavior of seabirds in the open ocean.
• To quantify the frequency and timing of seabird excretions at sea.
• To assess the potential ecological impact of seabird nutrient excretion.

Main Methods:

• Utilized belly-mounted video cameras to observe streaked shearwaters (Calonectris leucomelas) in their natural open ocean habitat.
• Recorded and analyzed excretion events, focusing on timing, frequency, and location (flight vs. surface).
• Estimated the mass and rate of excretion relative to body mass.

Main Results:

• Streaked shearwaters consistently avoided excreting while floating on the water surface.
• Excretion predominantly occurred during flight, with a periodicity of every 4-10 minutes during daylight.
• Excretion rate was estimated at approximately 5% of body mass per hour, potentially affecting flight energetics.

Conclusions:

• Seabird excretion behavior in the open ocean differs significantly from terrestrial observations.
• The regular, flight-based excretion of nutrients by seabirds may play a substantial role in marine nutrient cycling.
• This study provides crucial data for understanding seabird contributions to pelagic ecosystem processes and marine food webs.