The effects of warming on loggerhead turtle nesting counts

Global trends in marine turtle nesting numbers vary by region, influenced by environmental or anthropogenic factors. Our study investigates the potential role of past temperature fluctuations on these trends, particularly whether warmer beaches are linked to increased nesting due to higher female production (since sea turtles have temperature-dependent sex determination). We selected the loggerhead turtle (Caretta caretta) due to its wide distribution, strong philopatry, and vulnerability to environmental changes. We compiled nest counts per year on 35 globally significant rookeries, analysing trends at regional and individual beach levels. We compiled air (CHELSA) and land surface (MODIS) temperature datasets spanning the last four decades (1979-2023) for each location. To analyse temporal trends in nest counts and temperatures, we used generalised additive models and Mann-Kendall trend tests. Additionally, we correlated nest counts with lagged air temperature variables. We found signi..., , , # The effects of warming on loggerhead turtle nesting counts

[https://doi.org/10.5061/dryad.b8gtht7n5](https://doi.org/10.5061/dryad.b8gtht7n5)

## Description of the data and file structure

This dataset contains digitised polygons representing loggerhead turtle nesting beaches across the globe. The data were obtained by delineating polygons using Google satellite imagery within QGIS 3.32.2 (QGIS Development Team, 2020). Spatial-temporal fluctuations of nest counts across nesting grounds were analyzed using the Mann-Kendall trend analysis (Kendall, 1990) with the ‘MannKendall’ function in the R package ‘Kendall’. The dataset **does not include locations of nests**, and the polygons represent generalised beach boundaries** **and no precise nesting locations or coordinates have been included.

**File structure**

**Shapefile:** `nestingbeaches_GCB.shp`

* **Code:** Individual polygon code representing one beach.
* **Beach Name:** Name of the beach, when available.
* **Country:** Coun...