Land Use, anthropogenic disturbance, and riverine features drive patterns of habitat selection by a wintering waterbird in a semi-arid environment

Abstract

River ecosystems in semi-arid environments provide an array of resources that concentrate biodiversity, but also attract human settlement and support economic development. In the southwestern United States, land-use change, drought, and anthropogenic disturbance are compounding factors which have led to departures from historical conditions of river ecosystems, consequently affecting wildlife habitat, including important wintering areas for migratory birds. The Rio Grande (River) in central New Mexico is the lifeblood of the Middle Rio Grande Valley (MRGV), maintaining large urban and agricultural centers and riparian and wetland resources, which disproportionately support a diversity of wildlife. The MRGV has been identified as the most important wintering area for the Rocky Mountain Population of greater sandhill cranes (Antigone canadensis tabida). Presently, however, changes in the hydrogeomorphology of the Rio Grande and landscape modification by humans have reshaped the MRGV and winter habitat for sandhill cranes. To evaluate these impacts, we investigated how land-use practices, anthropogenic disturbance, and river morphology influenced patterns of diurnal and roosting habitat selection by sandhill cranes. During the diurnal period, sandhill cranes relied heavily on managed public lands selecting agriculture crops, such as corn fields, and wetlands for foraging and loafing while avoiding areas with increasing densities of human structures. Sandhill cranes selected areas for roosting in the Rio Grande characterized by shallower water interspersed with sandbars, wide channel width, low bank vegetation, and farther away from disturbances associated with bridges. Our results establish and identify the central processes driving patterns of diel habitat selection by wintering sandhill cranes. Land use and riverine trends have likely gradually reduced winter habitat to managed public lands and limited reaches of the Rio Grande, underscoring the importance of natural resources agencies in supporting migratory birds and challenges involved when managing for wildlife in highly pressured semi-arid environments.

The trade-off between fix rate and tracking duration on estimates of home range size and habitat selection for small vertebrates

“…For certain groups of species, such as small, nocturnal or range-limited species, gathering this information can be logistically challenging. As such, researchers are mostly reliant on indirect observation methods, such as animal-attached devices, including Very High Frequency (VHF) tags, geolocators and Global Positioning System (GPS) units [4] to make an assessment of what habitats are being used [5–7].…”

“…The rapid advancement of tracking technology has allowed us to remotely gather information on a wide variety of species [8,9], which can be used to answer questions about how the animal interacts with the landscape, how it moves in relation to habitat type and structure [5,10], its territoriality and interactions with conspecifics [11], and its foraging strategy [12]. GPS units in particular are associated with the ability to collect data from more locations, including previously inaccessible areas, at a higher level of accuracy than before [13,14].…”

Migration efficiency sustains connectivity across agroecological networks supporting sandhill crane migration

“…S2) with over 75% of days containing seven or more acquisitions per 24 h. In total, 187 unique northward spring migrations and 150 southward fall migrations were spatially inventoried. Detailed capture and GPS deployment procedures are provided in Collins et al (2016b), Nowak et al (2018), and Boggie et al (2018).…”

“…Inside migratory networks, we monitored wetland and agricultural resources (e.g., small grain cultivation) important to sandhill cranes (Pearse et al 2017, Boggie et al 2018. Wetland surface water extent was used as a proxy to wetland availability.…”

“…Wetland and agricultural monitoring results were used to generate a suite of spatially explicit v www.esajournals.org resource variables (Appendix S2: Table S1) important to structuring localized sandhill crane space-use patterns (Pearse et al 2017, Boggie et al 2018. Variables were ranked as predictors of local bird densities within stopover sites using randomForestSRC regression tree analysis (Ishwaran and Kogalur 2019) as a nonparametric measure of variable importance (VIMP).…”