Daily Wildlife Brief: Underwater-Fishing Birds - August 27, 2025

Main Takeaway: No major new events or incidents specifically involving birds that swim underwater to catch fish were reported on August 27, 2025. However, ongoing research and conservation efforts continue to shed light on the underwater foraging behaviours of cormorants, penguins and other pursuit-diving species.

Research Highlights

A recent University of Miami study detailed distinct physiological and behavioral strategies in two Florida waterbirds: the double-crested cormorant and the anhinga.

  • Cormorants pursue larger, deeper-water fish at higher oxygen costs, storing more oxygen in their leg muscles.
  • Anhingas ambush small fish in shallow waters, requiring less oxygen and achieving neutral buoyancy, allowing them to remain motionless underwater.

Conservation & Monitoring

  1. Ocean Temperature Profiling via Biologging: The Cormorant Oceanography Project has deployed temperature sensors on foraging cormorants to map coastal marine conditions. Each tagged bird provides up to 250 dives per day, yielding valuable data on temperature profiles and currents across 191 marine protected areas worldwide.
  2. Ship-to-Ship Fuel Transfer Regulations: New South African regulations effective August 25 aim to reduce offshore bunkering noise and oil-spill risk in Algoa Bay-home to endangered African penguins. Conservation groups warn these measures may insufficiently protect penguin foraging grounds from disturbance and pollution.

Species in Focus

SpeciesDiving MethodTypical Dive DepthForaging Strategy
African Penguin (Spheniscus demersus)Wing-propelled pursuit30-60 mSchools fish; vulnerable to noise and spills
Great Cormorant (Phalacrocorax carbo)Foot-propelled pursuit8-18 mBenthic feeding; year-round diving even in Polar night
Common Loon (Gavia immer)Foot-propelled pursuitUp to 60 mShallow-water ambush; affected by water clarity

Ongoing Challenges

  • Bycatch & Pollution: Gillnets and longlines continue to accidentally entrap diving seabirds, leading to mortality and conservation concern.
  • Climate & Food Supply: Shifting ocean temperatures and overfishing reduce prey availability, forcing some species to adapt dive depth and timing or face reproductive failure.

Despite no singular headline event on August 27, 2025, the collective body of research and policy updates underscores the critical balance between underwater-foraging birds and the health of marine ecosystems they rely on. Continuous monitoring, habitat protection and noise-pollution management remain paramount for the conservation of these specialized avian divers.