Ovarian Morphometry and Reproductive Activity in Roe Deer (Capreolus capreolus): Effects of Age, Body Mass, and Habitat Type

Reproductive performance in roe deer can vary with age, body mass, and habitat, but the relationships among these factors remain incompletely understood. We examined ovarian morphometry and reproductive activity in 105 female roe deer harvested in four hunting grounds in central Poland during 2023–2026. Ovarian length, width, circumference, follicle number, and corpora lutea number and area were assessed in relation to female age, habitat type, and pregnancy status based on macroscopic embryo detection. Ovarian length, width, and circumference increased with age, with the main differences occurring between yearlings and older females. Field-harvested females had greater body mass than forest-harvested females, but habitat type, age class, and body mass did not significantly explain variation in follicle number, corpora lutea number, or corpora lutea area among sexually mature females. Embryos were not detected in October or November; they were detected in 8.3% of females in December and 49% in January. These findings indicate that ovarian dimensions increase with age, whereas reproductive traits in sexually mature females show no clear differences between habitat types. The timing of embryo detection should also be considered when assessing pregnancy from reproductive tract examinations.