Environmental and geographic conditions on the breeding grounds drive Bergmannian clines in nightjars

Aim: To evaluate (1) whether three migratory nightjar species (Family Caprimulgidae) adhere to Bergmann's rule, (2) whether environmental factors on the breeding or wintering grounds determine body size, and (3) which mechanistic hypotheses best explain Bergmannian patterns in body size.
Location: North and South America; Europe, and Africa.Taxon: Eastern whip‐poor‐will (Antrostomus vociferus), Common nighthawk (Chordeiles minor), and European nightjar (Caprimulgus europaeus).
Methods: We used GPS tracking and morphometric data to assess competing hypotheses explaining variation in body size for each species, based on their breeding (n = 3388) and wintering (n = 189) locations.
Results: All three species exhibited Bergmannian patterns in body size, providing the first evidence that nightjars conform to Bergmann's rule despite adaptations to severe environmental conditions. Environmental and geographic variables at breeding sites were stronger predictors of body size than wintering‐site ..., , , # Data from: Environmental and geographic conditions on the breeding grounds drive Bergmannian clines in nightjars

## Manuscript Information

**Journal:** *Journal of Biogeography*

**Title:** Environmental and geographic conditions on the breeding grounds drive Bergmannian clines in Nightjars

**Authors:** Aaron A Skinner, Alicia M Korpach, Susanne Åkesson, Marja H Bakermans, Erin M Bayne, Thomas J. Benson, Giovanni Boano, R Mark Brigham, Simon S Christiansen, Greg J Conway, Christina M Davy, Ruben Evens, Kevin C Fraser, Autumn-Lynn Harrison, Anders Hedenström, Ian G Henderson, Juha Honkala, Lars B Jacobsen, Michiel Lathouwers, Peter P Marra, Janet W Ng, Gabriel Norevik, Amy L Scarpignato, Kasper Thorup, Christopher Tonra, Steven L Van Wilgenburg, Andrew C Vitz, Michael Ward, and Elly Knight

**Associated Files:**

* Manuscript: [https://onlinelibrary.wiley.com/doi/abs/10.1111/jbi.15176](https://onlinelibrary.wiley.com/doi/abs/10.1111/jbi.15176)\
* [GitHub repo](https://github.com/Lez...,