Relating form to function in the hummingbird feeding apparatus

Area of Science:

• Ornithology
• Comparative Anatomy
• Biomechanics

Background:

• Hummingbirds are a diverse avian clade specializing in nectarivory.
• Understanding their feeding apparatus is key to their survival and ecological niche.
• Tongue specialization is vital for intraoral transport of liquids and arthropods.

Purpose of the Study:

• To investigate the morphology and function of hummingbird tongues at multiple scales.
• To elucidate the anatomical structures critical for nectar feeding mechanisms.
• To understand the relationship between bill morphology and tongue structure.

Main Methods:

• Histology
• Transmission and scanning electron microscopy
• Microcomputed tomography (microCT)
• Ex-vivo experiments

Main Results:

• Hummingbird tongues feature a thin cornified epithelium without papillae.
• Tongues conform precisely to the internal shape of the bill's oropharyngeal cavity.
• Tongue groove walls exhibit structural composition and tissue architecture providing elastic properties.

Conclusions:

• The bill-tongue 'puzzle-piece' fit is essential for effective nectar intraoral transport.
• Elastic properties of the tongue are crucial for nectar-tongue interactions during feeding.
• These findings provide a basis for comparative studies in nectar-feeding birds.