Human choices, slope, and vegetation productivity determine pattern of traditional Alpine summer grazing

Grazing patterns in extensive pastures influence both animal productivity and conservation of grasslands ecosystem services. This study used Global Positioning Systems (GPS) tracking to describe the daily movement patterns and habitat selection of Simmental and Alpine grey lactating cows in the summer pastures of ‘Malga Ombretta’, located at 1900 m a.s.l. in the Dolomites, eastern Italian Alps (46.424549; 11.880871). During the study period (5 July–5 August 2018), the pastures (approximately 35 ha) were grazed by 14 Simmental and 7 Alpine grey cows (stocking rate =0.6 LU/ha). Each morning (8.00–9.00 am) the farmer-led the cows to graze in a different section of the pasture until 12.30–1.00 p.m. when cows were left free until they returned spontaneously to the barn (5.30–6.30 p.m), where they spent the night. Nine Simmental and 4 Alpine grey cows were equipped with GPS collars collecting one position/minute. Recorded positions were edited to exclude the in-barn night periods (final database =174,208 records) and used to describe grazing patterns at two temporal scales. At the daily scale, total distances walked varied from 2.0 to 8.9 km (mean: 4.7) across dates and increased with longer daily outdoor periods, reflecting the farmer’s choices of when/where to move the herd, but showed also a remarkable variation across individual cows, possibly because of individual features. No differences were found between breeds. At the step scale (i.e. for each interval between subsequent locations), slopes and altitudes used were higher, and walking speed was lower, in morning hours when cows were guided by the farmer than in afternoon hours when they were free. Slopes steeper than 30° were very seldom used, possibly indicating a threshold that cows are unwilling to trespass. Alpine grey cows used slightly higher slopes and altitudes and moved slightly faster than Simmental cows in the afternoon, suggesting a better adaption to difficult terrain conditions. Finally, in morning hours cows of both breeds used grassland patches with lower vegetation abundance, as indicated by the satellite-derived Normalized Difference Vegetation Index, than in afternoon hours. In this study, using high-frequency GPS tracking outlined the great variability of grazing patterns, and helped to understand how they can be influenced by human (farmer’s decisions) and animal (breed, but also individual) choices.