Skip to content

Male and Female Fallow Deer Followed Different Daily Schedules Outside the Rut

European fallow deer hind in Amsterdamse Waterleidingduinen
Research · Behaviour

European fallow deer in a heavily managed Dutch dune reserve were consistently more active in low light than during the day, but males and females followed different seasonal schedules outside the rut. Researchers analysed 4,114 sexed camera-trap detections from the Amsterdamse Waterleidingduinen and found that the apparent spring increase in daytime activity was driven largely by males.

The study used 49 cameras during three 10-day periods representing the birthing season in April 2024, the rut in October 2024 and the post-rut period in January 2025. Activity was classified relative to the amount of daylight, twilight and darkness available in each season, so seasonal changes in day length would not by themselves look like behavioural change.

Night and twilight dominated overall

At population level, fallow deer (Dama dama) preferentially used twilight and night. During the rut and post-rut periods the best description was a nocturnal–twilight pattern, while the birthing season shifted toward a predominantly twilight pattern. Daytime remained used less than expected from its availability.

Pooling the sexes, however, concealed important differences. During the rut, males and females had broadly similar activity peaks around sunset and the early night, and their temporal overlap was highest. Outside the mating season their schedules diverged.

Females remained more nocturnal

After the rut, females showed persistent nocturnal activity concentrated around sunset and night, whereas males used a broader part of the day. The divergence became especially clear in the birthing season: females continued to favour low-light periods, while males increased twilight and daytime activity.

The study therefore shows that the springtime shift toward more daytime activity was not a population-wide change. It was largely produced by males. Analyses that combine both sexes would miss this sexual segregation in activity timing.

A landscape shaped by people

The Amsterdamse Waterleidingduinen receives substantial daytime recreation, lacks large natural predators and has had a population-control programme since 2016. Culling occurs mainly from November to March and focuses particularly on females and fawns. These conditions create a landscape in which human disturbance and management vary through both the day and the year.

These differences could reflect several processes. Males may change how they forage and recover energy reserves after the costly autumn rut, while females face different energetic demands during pregnancy and when caring for fawns. Daytime recreation and sex-biased culling could also affect when each sex moves, but the camera study cannot determine which mechanism explains the patterns. The finding has a practical consequence for wildlife monitoring: surveys conducted at only certain times of day may detect proportionally fewer of the more nocturnal females. The study did not measure a bias in population estimates, but it shows why combining both sexes can conceal an important aspect of fallow deer behaviour.

Sources and image credit

  1. de Lange, A., Geelen, L. H. W. T., & Kissling, W. D. (2026). Low-light activity in fallow deer shows sex-specific seasonal changes in a managed landscape. Mammal Research, 71, 82.Primary open-access article first published 29 September 2026. Full text checked. The study used 49 camera traps and 4,114 sexed detections from Amsterdamse Waterleidingduinen, Netherlands, across rut, post-rut and birthing periods.

Image: European fallow deer (Dama dama) hind in Amsterdamse Waterleidingduinen, Netherlands, 27 September 2014. Photo: K.vliet / Wikimedia Commons. CC BY-SA 4.0. Representative image from the study area; not a study detection. · CC BY-SA 4.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

Behaviour

SPECIES IN THIS STORY

Species in this story

European Fallow Deer Dama dama Explore species

Independent research and conservation news archive

Did you find this information useful?

Wildlife Vagabond is independently built and maintained. Voluntary support helps cover source verification, hosting and continued work on research and conservation news.

Support Wildlife Vagabond

The news archive will remain freely available.