The nightjar and the ant: Intercontinental migration reveals a cryptic interaction

Area of Science:

• Ecology
• Zoology
• Ornithology

Background:

• Birds and ants interact in diverse ways, including competition, mutualism, and predation.
• Ant-induced injuries in birds are understudied, particularly the long-term impacts on migratory species.

Purpose of the Study:

• To quantify toe amputations from ant bites in a red-necked nightjar population.
• To identify ant species responsible for these injuries using taxonomic analysis of mandible remains.

Main Methods:

• Monitoring a migratory red-necked nightjar (Caprimulgus ruficollis) population for 15 years (2009-2023) in southern Spain.
• Examining adult and juvenile birds for toe amputations and analyzing attached ant mandible remains taxonomically.

Main Results:

• Less than 1% of adult nightjars (N=369) had toe amputations; African army ants (Dorylus sp.) were identified as the primary cause.
• Ant mandible remains were found on injured toes, indicating potential for attachment even after intercontinental migration.
• Juveniles (N=269) showed no severe damage, except for one case involving a local ant species (Messor barbarus).

Conclusions:

• Ant bites, particularly from African army ants, pose a threat to migratory nightjars, with potential implications for survival and population health.
• Further research in tropical areas is crucial to assess the full eco-evolutionary impact of these antagonistic ant-bird interactions.