Metabarcoding reveals seasonal variations in the consumption of crops and weeds by wild Red-legged Partridge Alectoris rufa

The intensification of agriculture is impacting farmland and is recognised as a main driver for biodiversity loss in these environments. Many farmland bird populations have been declining in recent decades because of agricultural intensification. This is the case of the Red-legged Partridge Alectoris rufa, a game bird that inhabits farming landscapes and has recently suffered drastic population declines in Spain. To fully understand the effects that agricultural intensification has on these birds, it is crucial to deepen the knowledge regarding their feeding habits and how these may vary seasonally. The aim of this study was to provide a detailed and reliable description of wild partridges' plant diet composition. For this purpose, we collected faecal samples from 35 partridge flocks during autumn, winter and spring, and used DNA metabarcoding to identify plants consumed by this species. We used nuclear and chloroplastic barcodes for the amplification of ITS2 and rbcL gene regions, respectively. Our results showed that the diet of partridges was highly diverse, mainly consisting of cereals, weeds and legumes. The most frequently consumed genus was Hordeum, followed by Lolium, Papaver, Medicago and Avena. We further showed that diet composition varied significantly amongst seasons, with a higher proportion of cultivated plants (> 25%) being consumed during autumn and winter. During the cereal sowing period, cropped plants might be consumed as sown seeds, which are often coated with pesticides and could represent an important risk. In spring, before breeding, the diet was mostly composed of weeds. Plants of the Papaver genus could be consumed for anti-parasitic purposes, and as a source of antioxidants and carotenoids to increase ornamental coloration, especially during pairing and laying. Our results highlight the importance of maintaining heterogenous farming landscapes with fallow lands and field margins as sources of weeds to help the conservation of this species.

Automated summary

The intensification of agriculture has had a significant impact on the Red-legged Partridge population in farmland landscapes. This study provides a detailed description of their plant diet, highlighting the variation in diet composition across seasons.