Assessing migratory connectivity for a long-distance migratory bird using multiple intrinsic markers

Area of Science:

• Ornithology
• Ecology
• Evolutionary Biology

Background:

• Migratory connectivity in birds is essential for understanding their ecology and evolution but is often difficult to study due to data limitations.
• Probabilistic assignment methods are advancing, integrating stable isotopes with other data types to enhance accuracy in ecological studies.
• Accurate migratory connectivity data is vital for effective conservation strategies for migratory bird populations.

Purpose of the Study:

• To probabilistically assign Wood Thrush (Hylocichla mustilena) wintering individuals to their specific breeding locations.
• To assess the effectiveness of combining stable isotopes with geographic variation in morphology (wing length) for improving migratory connectivity estimates.
• To validate the developed model using known-origin samples and evaluate the influence of covariates like age, sex, and breeding location.

Main Methods:

• Stable isotope analysis of Wood Thrush samples.
• Measurement of geographic variation in wing length (morphology).
• Development and validation of a probabilistic assignment model integrating isotopic and morphological data.

Main Results:

• Moderate migratory connectivity was identified in Wood Thrushes, primarily along an east-west gradient, despite significant mixing across ranges.
• Combining stable isotopes with wing length variation improved breeding assignment precision by 10% (isotopes alone) and 37% (wing length alone).
• Geographic variation in morphology proved to be a valuable intrinsic marker for enhancing migratory connectivity estimates.

Conclusions:

• Geographic variation in morphological traits significantly enhances the precision of migratory connectivity estimates when integrated with other markers like stable isotopes.
• Museum collections offer a vast, underutilized resource for quantifying migratory connectivity patterns in birds.
• This integrated approach provides a more accurate understanding of Wood Thrush migratory connectivity, informing conservation efforts.