USFWS Grant: Sandhill Cranes Conservation in the Great Plains

The Inventory and Monitoring (I&M) Plan for Muleshoe National Wildlife Refuges (NWR) calls for quantifying landscape carrying capacity and assessing the threats for the mid-continent population of sandhill cranes (Grus canadensis) that winter on or near the refuge. The primary purpose of such an effort would be to assess the role of Muleshoe NWR and the immediate surrounding landscape in context of overwintering ecology of the Mid-Continent Population (MCP) of sandhill cranes. The goal is to assess what constitutes sustainable landscapes for sandhill cranes and what are the possible management strategies that can be put into place to protect these landscapes. Similarly, the U.S. Fish and Wildlife (USFWS) regions advanced Strategic Habitat Conservation (SHC) in early 2014 through the selection of surrogate species in key geographic areas within existing Landscape Conservation Cooperatives (LCC). A key uncertainty of the surrogate species approach is the ability of a species and its population metric (i.e., what we can effectively monitor) to appropriately represent conservation objectives or ecological conditions (Athearn et al. 2013; Caro 2010) that support other species and community processes across a landscape.

One objective of this project is to develop a bioenergetics model that incorporates the role of Muleshoe NWR for species conservation in context of a changing landscape due to climate change and its subsequent effects on land use in the High Plains. Although our target species is sandhill cranes, identification of suitable landscapes for this species will also benefit other sensitive species through the identification and spatial arrangement of suitable habitats (i.e. Conservation Reserve Program (CRP) lands, agricultural lands, pluvial saline lakes, playa wetlands). A second objective of this project focuses on assessing the suitability of using the crane as a surrogate for the needs of other species, identification of which species may be represented, and identification of a mechanism for using information about cranes to support management of a larger pool of species.

Approximately 82 percent of the MCP of sandhill cranes winter on the Southern High Plains (SHP) of Texas (Krapu et al. 2011). Within this population, 3 of the 4 distinct geographic breeding affiliations spent greater than 60 percent of their winter on the SHP, making this region critical to the ecology and persistence of the MCP. The SHP is among the most agriculturally impacted regions in the Western Hemisphere. The existing landscape is a matrix of various crops, CRP lands, native rangelands, ephemeral playas, and saline pluvial lakes that support several wildlife species. Distribution of sandhill cranes on the SHP is influenced by the presence of saline pluvial lakes (Krapu et al. 2011) located in large tracts of native prairie near agricultural lands consisting of high-energy waste grains (sorghum; Iverson et al. 1985). Of the 20 pluvial saline lakes located on the SHP, only 4 belong to public trust, and 3 are located at Muleshoe NWR in Bailey County, Texas, and the other is at Grulla NWR in Roosevelt County, New Mexico.

Count estimates suggest about 3-45 percent of the entire Mid-Continent Population use Muleshoe NWR as overwinter habitat, with increases in use since the year 2006 (about 15-45 percent of MCP). The surrounding landscape consists of native rangelands and CRP, but is primarily dominated by agricultural lands. Sandhill cranes roost on the pluvial saline lakes on the refuge and forage on privately owned agricultural lands. Thus, land management practices on Muleshoe NWR (maintenance of native rangeland and saline lakes) and surrounding private lands (waste grain availability) influence sandhill cranes distribution and overwinter survival in this region. However, the arrangement, connectivity, and availability of vital habitats in this region have not been assessed for sandhill cranes, despite this region’s significance to the persistence of this important game and cultural species. This information is vital toward the development of sound management strategies for the refuge and surrounding landscapes (a landscape conservation design), particularly in the long term, as the SHP is expected to become hotter and drier, with decreases in, yet increased intensity of, precipitation events due to climate change (Karl et al. 2009).

USFWS uses a science-based adaptive framework for setting and achieving broad-scale conservation objectives that strategically address the problems fish and wildlife will face in the future. This framework, called SHC, is based on the principles of adaptive management and uses population and habitat data, ecological models, and focused monitoring and assessment efforts to develop and implement strategies that result in measurable fish and wildlife population outcomes. This process uses the best available scientific information to predict how fish and wildlife populations will respond to changes in the environment, thus enabling the USFWS to focus habitat conservation and other management activities where they will be most effective. In addition, the USFWS needs focused, applied science directed at high impact questions surrounding threats to fish and wildlife resources for which management and/or mitigation is required to maintain species at healthy, sustainable, desired levels. USFWS must base its decisions on the best science available, in order to defend its regulatory decisions, biological opinions and species conservation recommendations to land managers.