Seasonal Divergence of Landscape Use by Heritage and Conventional Cattle on Desert Rangeland

Abstract

Adopting livestock with heritage genetics may help to improve the sustainability of agriculture on rangelands with harsh, challenging conditions. In the Chihuahuan Desert, preliminary evidence suggests that heritage Raramuri Criollo exploit a greater variety of range resources than do conventional cattle. Accordingly, the use of Raramuri Criollo may help sustain vegetation and soils, as well as agricultural production. To explore these possibilities, we used Global Positioning System collars to track Angus × Hereford and Raramuri Criollo cows in a 1 535-ha pasture in southern New Mexico in June–December 2008. As predicted on the basis of past research, home range sizes of Raramuri Criollo exceeded those of Angus × Hereford during seasons with low forage availability—by 31.4 ± 6.5 ha during Pregreenup and 17.2 ± 6.5 ha during Drydown—but sizes converged during more productive seasons (Greenup 1, Greenup 2). Angus × Hereford allotted more daily time to resting, with the difference most pronounced during Drydown (71.1 ± 21.1 min day^− 1). Angus × Hereford had twice as many hotspots of use (locations with multiple visits of long duration), with seasonal timing and location corresponding with distribution patterns known to impact desirable natural resources. Raramuri Criollo more strongly preferred the Bare/Forbs ecological state with seasonal timing that possibly signals an ability to use nutritious forbs on open ground despite summer heat. Results are consistent with conjectures that compared with conventional cattle, Raramuri Criollo have greater daily mobility and wider spatial distribution during dry seasons. Although not directly measured, results also suggest that the heritage breed has superior heat tolerance and lower impact on desirable natural resources. These findings provide evidence that Raramuri Criollo can support sustainable livestock production in the Chihuahuan Desert, but direct measurements of profitability and environmental effects are needed before adoption can be recommended widely.

Introduction

Livestock production and natural resource conservation are long-standing goals for rangelands, but achieving both simultaneously is an ongoing management challenge. Managing livestock distribution so that both animal and range productivity are sustained is desirable, but such distribution is often hampered by livestock behavior that results in uneven use of pastures. Manipulating fencing, water locations, and timing of use are common approaches to improving livestock distribution (Heitschmidt and Taylor, 1991, Owens et al., 1991). These manipulations, however, can be cost-prohibitive or inadequate in rangelands characterized by challenging conditions of large pasture sizes (Hunt et al., 2007), dense woody vegetation (Gutman et al., 2000), steep terrain (Bailey, 2004), or hot temperatures (Swain et al., 2007).

In rangelands with these challenging conditions from the Chihuahuan Desert to subtropical Florida to Mediterranean Israel, recognition is growing that using locally adapted breeds genetically predisposed to use resources in the context of local environmental variation can result in livestock distribution that is aligned with sustainable management goals (Sponenberg and Olson, 1992, Dumont et al., 2007, Estell et al., 2012, Shabtay, 2015, Scasta et al., 2016). In the Chihuahuan Desert, research is under way to investigate the distribution and landscape use of Raramuri Criollo (RC) cattle, a small-framed heritage breed that has undergone 500 years of adaptation to the harsh conditions of the Sierra Tarahumara in northern Mexico (Fig. 1) with minimal genetic influence of improved beef breeds (Anderson et al., 2015).

Preliminary evidence suggests that RC differ in important ways from the Angus breeds typically used in the Chihuahuan Desert (e.g., Brangus, Angus × Hereford [AH]). For instance, in the Sierra Tarahumara, RC have been observed to subsist mainly on woody plants, cacti (Ortega-Ochoa et al., 2008, Anderson et al., 2015), and forbs (Carswell, 2014) instead of mainly on grasses as is common for conventional breeds of the Chihuahuan Desert (Winder et al., 1996, Estell et al., 2012). Early-adopter producers have observed that the heritage cattle appear to travel across desert pastures more continually than conventional cattle, even in the heat of the summer (Carswell, 2014, Moreno, 2017). In addition, telemetry research during the course of 2005 showed that during months when forage was sparse and patchily distributed in a large Chihuahuan Desert pasture, RC distributed themselves more widely than AH, presumably seeking forage in distal portions of the pasture (Peinetti et al., 2011). Diet breadth, heat tolerance, and mothering style are possible behavioral explanations for observed breed differences in behavior and landscape use (Nyamuryekung’e et al., 2017; Nyamuryekung'e et al. in review).

To advance knowledge about whether and how the heritage breed differs from a breed used conventionally, we used Global Positioning System (GPS) collars to track RC and AH cows without calves during four phenologically defined seasons in June–December 2008 across a 1 535-ha pasture at the Jornada Experimental Range in southern New Mexico. The RC and AH herds grazed the pasture separately in successive 6-d trials within each season. We compared the herds in terms of home range sizes and spatial extents, daily activity budgets, hotspots of use, and preferences for ecological states while foraging. Tracking across multiple seasons was a priority because primary production, and livestock responses to it, vary greatly within and between years in arid lands (Thomey et al., 2011).

Anecdotal evidence and past research were the basis for four predictions about possible breed differences in landscape use during the study, with the first prediction pertaining to spatial extent. Peinetti et al. (2011) also compared the landscape use of RC and AH cows across a progression of seasons on a large pasture on the Jornada Experimental Range. The authors found that in the spring of 2005, when green forage was relatively plentiful and well distributed, the AH and RC herds exhibited similar spatial extents and spatial relationships to watering sites. Conversely, in the fall of 2005, when green forage was relatively scarce and patchily distributed, RC foraged across a larger spatial extent while AH had a smaller range that was closer to water. Accordingly, we predicted that during periods of relatively low forage production in our study, individual home range sizes and herd-level spatial extents of RC would be larger than those of AH, but during periods with more plentiful forage, home range sizes and spatial extents of the herds would converge.

Our second prediction was founded on anecdotal observations of early-adopter producers about the mobility of the heritage breed (Carswell, 2014, Moreno, 2017). Correspondingly, we predicted that the conventional cattle would spend more time resting each day while the heritage cattle would allot more time to moving across the pasture either foraging or walking.

Thirdly, we hypothesized that if in comparison with AH, RC did indeed cover a wider spatial extent in certain seasons and spend more daily time moving across the pasture—as hypothesized per the first two predictions—then RC would revisit particular locations less frequently and remain at those locations for less time. In our analysis, this would translate into fewer hotspots of use (i.e., locations with multiple visits of long duration). Understanding spatial and temporal distribution of hotspots in the Chihuahuan Desert is important because overuse of particular pasture locations is associated with social-ecological issues including perennial grass loss (Bestelmeyer et al., 2009), lateral soil redistribution (Nash et al., 2003), dust emissions (Baddock et al., 2011), and suboptimal utilization of the overall forage base (Holechek, 1992, Hunt et al., 2007).

Through our fourth prediction we explored the selection of ecological states by the cows while they were foraging. Given that RC subsist on woody plants, cacti, and forbs in their native Sierra Tarahumara (Ortega-Ochoa et al., 2008, Carswell, 2014, Anderson et al., 2015) and the contrasting tendency for Angus breeds to generally prefer grasses in the Chihuahuan Desert (Winder et al., 1996, Estell et al., 2012), we predicted that throughout most of the study, RC would concentrate foraging time on forb-dominated states and shrub-dominated states, whereas AH would concentrate foraging time on grass-dominated states. We sought to understand these patterns because preferential use of ecological states can affect supplemental feed requirements and the management of ecological state transitions—both of which influence the sustainability of agriculture on arid rangelands (Bestelmeyer et al., 2013).

We acknowledge that this was a 1-yr study and that replication of breed × season treatments will be required for a definitive comparison of heritage and conventional cattle in the Chihuahuan Desert. However, this study is valuable as it entailed monitoring RC and AH over multiple seasons and identifying livestock preferences for mapped ecological states (Steele et al., 2012), an aspect of livestock landscape use that has not yet, to our knowledge, been quantified. This is also the first study to use Time Local Convex Hulls (T-LoCoH) (Lyons et al., 2013) to construct home ranges and time-use maps to quantify livestock distribution. Further, we defined seasons for the study period using Normalized Difference Vegetation Index (NDVI) from satellite data (Browning et al., 2018). Ecological state mapping and the procedure for defining seasons are applicable to any pasture, so while our telemetry dataset spans only 1 yr, our use of reproducible approaches to characterize conditions improves chances for accurate comparisons between our livestock telemetry results and those from different locations in different years.