Why do zoos attract crows? A comparative study from Europe and Asia

Area of Science:

• Urban ecology
• Ornithology
• Conservation biology

Background:

• Crows (Corvus spp.) are successful urban colonizers.
• Urban zoos play a role in crow distribution and behavior.

Purpose of the Study:

• To quantify crow numbers and behavior in urban zoos across Europe and Asia.
• To identify factors attracting crows to zoo environments.

Main Methods:

• Conducted 445 surveys over 297 days in summer and winter 2014-2015.
• Monitored crow populations and behaviors in zoos in Debrecen, Edinburgh, Vienna, and Sapporo.
• Assessed food availability (natural and anthropogenic) and habitat structure.

Main Results:

• Crow numbers varied significantly between zoos and seasons, peaking in Vienna and increasing in winter.
• Higher crow numbers correlated with sunny weather and lower visitor numbers.
• Anthropogenic food use was high in zoos with limited natural foraging areas.

Conclusions:

• Food availability is the primary attractant for crows in urban zoos, followed by breeding opportunities.
• The type of food source utilized by crows depends on zoo habitat structure.
• Zoos may play an overlooked role in urban biodiversity and crow population management.