Multiple drivers of spring migration timing for red deer over the past 16 years in northern Europe

The timing of migration is fundamental for species exploiting seasonally variable environments. For ungulates, earlier spring migration is expected with earlier vegetation green-up. However, other drivers, such as access to agricultural farmland and variations in local conditions, are also known to affect migration. We investigated the timing of spring migration for 96 male and 201 female red deer (Cervus elaphus) using a long-term dataset (2005-2020). Overall, the timing of migration was mainly characterised by large individual variability between and within years (95% range from April 6th to June 18th). The spring migration timing was, as expected, later with colder winter and spring conditions (NAO winter and April indices) and later peak vegetation green-up (NDVI), with a 5-day delay in green-up causing a migration delay of 1.2 days. The timing was also influenced by local conditions in summer and winter home ranges. Red deer with higher access to farmland and more variable topograp..., , , # Multiple drivers of spring migration timing for red deer over the past 16 years in northern Europe

[https://doi.org/10.5061/dryad.d7wm37q7b](https://doi.org/10.5061/dryad.d7wm37q7b)

## Description of the data and file structure

The data includes three files, one for the analysis of the trend (\"trends_data.RData\") one for the analysis of the drivers of spring migration onset (\"drivers_data.RData\") for red deer, and one for the analysis of the NDVI patterns within the home ranges of the red deer (\"ndvi_patterns_data.RData). 

The files include the following information:

* **trends_data**.RData: id, year, year_sc (= year mean-centred), sex.y (= sex), spring.start.julian (= the day of the year of migration onset), and region2 (= region).
* **drivers_data.RData**: yr (= year), id, region, spring.start.julian (= the day of the year of migration onset), dens (= population density index, number of shot red deer per km2), pasture (= proportion of available farmland within the winter home...