The North American Beaver (Castor canadensis) is Recolonizing the Llano Estacado

Five millennia ago, the North American Beaver (Castor canadensis) was extirpated from the Southern High Plains by droughts. Beaver were found to be largely absent from the Llano Estacado, despite exhaustive search efforts. Here we report the first definitive evidence of an extant C. canadensis population recolonizing the Llano Estacado.

Food Habits of American Kestrels In the Southern High Plains of Texas

ABSTRACT The American Kestrel (Falco sparverius) is in general decline across its North American distribution. In contrast to widespread patterns of decline, kestrel populations appear stable in the southern Great Plains region. Historically, this region had a very low occurrence of kestrels, and their current abundance is highly likely due to vegetation and structures associated with settlement by people of European descent. To determine prey use by breeding kestrels, we placed motion-activated video cameras at preexisting kestrel nest boxes located in the Southern High Plains in 2017. We recorded over 4200 prey deliveries during 1748 hr of observation at five nests over the 4-wk brood-rearing period. On basis of frequency, these deliveries were dominated by reptiles (74.8%), with invertebrates (18.2%), mammals (4.4%), birds (2.9%), and unidentified (1.2%) prey used to lesser extents. Prey delivery rates were high relative to other studies; across the brood-rearing period we recorded an average of 2.3 deliveries/hr, equating to an average of 0.49 deliveries and 3.85 g of prey/nestling/hr. Because invertebrates dominate the diet reported in most kestrel food habit studies, the volume of reptiles captured as prey was unexpected. Even more unanticipated was the number of large prey captured, including juvenile eastern cottontails (Sylvilagus floridanus) and ground squirrels (Ictidomys tridecemlineatus, Xerospermophilus spilosoma). We suspect the proportion of vertebrate prey captured during the nesting season may explain the local high rates of nesting success and number of young fledged.

Late Quaternary Stratigraphy and Geochronology of the Spring Creek Drainage along the Southern High Plains Eastern Escarpment, Northwest Texas

The eastern escarpment breaks of the Southern High Plains of Texas are both a geomorphic and ecotonal transition zone from the high plains surface to the Rolling Plains below. The geoarchaeological record on the Southern High Plains surface is well documented, but few studies have investigated the sediments, soils, and geochronology of the eastern escarpment. The current investigation has targeted the discontinuous remnants of Late Quaternary deposits within Spring Creek, a tributary within the upper Brazos River basin. A total of 19 profiles, core, and isolated exposure locations placed along a transect from Macy Fork through upper Spring Creek and 40 radiocarbon ages provide a composite sequence and geochronology that also documents the Late Pleistocene to Late Holocene paleoenvironments of this drainage. The resulting record illustrates a series of major changes in sediments and local habitats over the past ~11,550 radiocarbon years (13,469–13,390 calendar years), characterized primarily by reductions in available water and increasing aridity that peaked during the middle Holocene. This sequence provides significant context to an expanding record of Late Pleistocene to middle Holocene biota and cultures. Subsequent downcutting of the drainage post-6000 14C yr B.P. (6988–6744 calendar years) removed large sections of the depositional sequence. Local topography within Spring Creek drainage greatly impacted the preservation of these deposits. The remaining record provides some different insights than those available from the Southern High Plains record.

Cover Crop Management on the Southern High Plains: Impacts on Crop Productivity and Soil Water Depletion

The imminent depletion of the Ogallala Aquifer demands innovative cropping alternatives. Even though the benefits of cover crops are well recognized, adoption has been slow in the Southern High Plains (SHP) of the United States because of concerns that cover crops withdraw soil water to the detriment of the summer crops. This small plot experiment tested the interacting effects—production, soil water depletion of the cover crops, and subsequent teff [Eragrostis tef (Zucc.) Trotter] summer hay crops—of irrigation and tillage management with five cover crop types to identify low-risk cover crop practices in the drought-prone SHP. Dryland rye (Secale cereale L.) produced modest forage biomass (>1000 kg ha−1), even in a dry year, but it was found that light irrigation should be used to ensure adequate forage supply (>1200 kg ha−1) if winter grazing is desired. No-till management and timely termination of the winter cover crops were crucial to reducing the negative impact of winter crops on summer teff production. The results indicated no detriment to soil water content that was attributable to planting no-till cover crops compared with the conventional practice of winter fallow. Therefore, producers could take advantage of the soil-conserving attributes of high-quality winter forage cover crops without experiencing significant soil water depletion.

A Geographical Survey of Center Pivot Irrigation Systems in the Central and Southern High Plains Aquifer Region of the United States

HighlightsAll center pivot irrigation systems in the Central and Southern High Plains Aquifer region were digitized.Out of 2.76 Mha under center pivots, the largest portion (58%) was in Texas and the smallest (2%) in Colorado.Most center pivots were about 50 ha, with a range of 1 to >230 ha.The new layer can be used in extracting distributed soil, weather, and crop data for various precision agriculture applications.Abstract. With the declines in water levels of the Central and Southern High Plains Aquifer, there is a critical need to accurately map the irrigated agriculture in this region as it is the largest user of groundwater resources. The goal of this study was to develop a geospatial database of all areas under the most dominant irrigation system in the region: center pivots. The borders of all center pivots (50,116) were manually digitized using high spatial resolution satellite imagery, delineating the area that can be potentially irrigated by these systems. Most center pivots were comparable in size (ca. 50 ha), with a range of 1 to >230 ha. The areas of digitized center pivots at the state and study area levels were relatively close to estimates of two actual irrigated area products based on automatic land classification. The new layer was also used to extract available data on groundwater level changes since predevelopment (before 1950). Aquifer regions under center pivots in Colorado and Texas had the smallest and largest declines in water level, respectively. The new layer offers advantages in terms of accurately identifying the area covered by center pivots and has potential research and practical applications such as studying adopted practices in response to water level declines, assessing field-scale irrigation uniformity, and extracting distributed soil, weather, and crop data to be used in various precision agriculture applications. The new layer is freely available to the public as supplemental information of this article (https://doi.org/10.13031/14707284). Keywords: Groundwater decline, Irrigated fields, Ogallala, Sprinkler irrigation.

Topographic Thresholds and Soil Preservation along the Southern High Plains Eastern Escarpment, Northwest Texas, USA

The eastern escarpment of the Southern High Plains (USA) is today a semi-arid erosional landscape delineated by canyon breaks and topographic relief. A series of buried soils were identified, described, and sampled at 19 soil profile localities exposed along terraces of the South Fork of the Double Mountain Fork of the Brazos River (South Fork) and two associated tributaries (Spring Creek and Macy 285 drainage). Radiocarbon dating revealed late-Pleistocene to early Holocene (~12,580–9100 14C B.P.), middle-Holocene (~6025–4600 14C B.P.), and late-Holocene (~2000–800 14C B.P.) buried soils. The late-Pleistocene to middle-Holocene soils were preserved only at higher elevations within the upper section of the South Fork and Spring Creek. A topographic position analysis was conducted using GIS to identify and examine the impacts of a soil topographic threshold on the preservation and distribution of buried soils within this geomorphic system. Above the identified ~810 m threshold, lateral migration of channels was constrained. Extensive channel migration below the threshold removed older terraces that were replaced with late-Holocene terraces and associated buried soils. Landscape topography constraints on geomorphic processes and soil formation impacted the preservation of archaeological sites in this semi-arid region.