Influence of monsoon rainfall events on movement patterns of Angus crossbred vs. Raramuri Criollo cattle on desert rangeland

The Chihuahuan Desert averages 247 mm of precipitation annually, 53% of which occurs between July and September. Our objective was to examine movement, activity, pasture use, and watering patterns of Angus x Hereford (AH) and Raramuri Criollo (RC) cows on days with precipitation events (PE, > 1.3 mm rain recorded) vs. days with no precipitation (NP) at the Jornada Experimental Range in southern New Mexico during the summers of 2015, 2016, and 2017. Breeds grazed two adjacent pastures (12A = 1190 ha; 12C = 1165 ha) separately in a crossover design for 4 weeks each year. Seven to nine randomly selected cows per breed were collared with Lotek 3300-LR GPS set to log position every 10 min. An average of 7.6 PE occurred during the 4-week trials each year. On PE days, cows traveled farther (PE = 6.95 vs. NP = 6.43 km, P < 0.01), spent more time grazing (PE = 9.07 vs. NP = 8.76 h/day, P = 0.07) and less time resting (PE = 13.90 vs. NP = 14.38 h/day, P = 0.01), and traveled similar distances from watering points (PE = 0.84 vs. NP = 0.80 km, P = 0.41) compared to NP days. On PE days, cows spent less time within 200 m (PE = 1.32 vs. NP = 2.95 h, P < 0.01) and 100 m (PE = 0.79 vs. NP = 1.90 h, P < 0.01) of drinkers regardless of breed. We detected no rainfall x breed interaction (P > 0.05). Overall, RC cows traveled farther, at higher velocities, spent more time grazing, less time resting, and explored areas with greater radius than AH counterparts (P < 0.05). Precipitation appeared to relax environmental constraints on activity of both breeds, likely due to availability of ephemeral watering sources and a transient drop in temperature.