Changing Rainfall Drives Locally Asynchronous Reproduction of Tropical Birds via Modular Trophic Pathways

Area of Science:

• Ecology and climate change research
• Tropical ecosystem dynamics
• Avian reproductive phenology

Background:

• Phenological shifts are a key indicator of climate change impacts.
• Understanding these shifts in diverse tropical ecosystems is crucial but limited.
• Reproductive timing in tropical birds is influenced by rainfall patterns.

Purpose of the Study:

• To investigate how rainfall seasonality affects breeding phenology across different trophic levels in tropical birds.
• To test hypotheses linking avian reproduction to rainfall timing and intensity.
• To identify potential ecological tipping points related to dry season intensity.

Main Methods:

• Utilized comprehensive multitrophic datasets and in-situ meteorological data.
• Analyzed breeding timing in relation to wet and dry seasons for nectarivores, frugivores, and insectivores.
• Examined spatial and temporal variations in reproductive strategies across elevation and rainfall gradients.

Main Results:

• Nectar and fruit-eating birds exhibited seasonal breeding tied to flowering/fruiting, with little variation.
• Arthropod-eating birds showed significant local shifts in breeding timing (up to 5 months) correlated with dry season intensity.
• Insectivores displayed spatially asynchronous reproduction, with some species skipping breeding in dry years and others advancing nesting.

Conclusions:

• Rainfall magnitude and dry season intensity create ecological tipping points, compartmentalizing food webs.
• Different trophic groups exhibit distinct responses to rainfall variability, indicating quasi-independent pathways.
• Insectivore phenological shifts serve as an early warning signal for climate change impacts on tropical ecosystems.