Coevolution between Himalayan cuckoos and 2 sympatric Pycnonotidae hosts.

Area of Science:

• Evolutionary biology
• Behavioral ecology
• Ornithology

Background:

• Brood parasitism drives the evolution of host defenses.
• Sympatric host species may develop varied anti-parasitism strategies.
• Cuckoo-host interactions differ based on host species and location.

Purpose of the Study:

• Investigate coevolutionary interactions between Himalayan cuckoos and two sympatric Pycnonotidae hosts.
• Compare nest-site selection, nest defense, and egg rejection strategies.
• Determine how these differences influence cuckoo parasitism rates.

Main Methods:

• Studied parasitism rates and nest-site selection (nest height, cover, human disturbance, perch height, forest distance, concealment).
• Assessed nest defense against a cuckoo dummy.
• Evaluated egg rejection against cuckoo model eggs.

Main Results:

• Brown-breasted bulbuls selected nest sites farther from forests than finchbills.
• Bulbuls exhibited more aggressive nest defense against cuckoos than finchbills.
• Finchbills rejected 100% of model cuckoo eggs, while bulbuls had moderate rejection ability.

Conclusions:

• Bulbul's avoidance of forest nesting sites likely explains the absence of Himalayan cuckoo parasitism.
• Interspecific differences in nest-site selection and defense represent alternative evolutionary responses to cuckoo selection pressures.