Wide channels with short bank vegetation, access to nearby foraging habitat, shallow water areas (<30 cm deep), and absence of disturbance features are factors commonly associated with suitable roost sites for Sandhill Cranes (Antigone canadensis). However, since channel width has typically been evaluated independently of channel depth and flow, it is possible that use of narrow channels is not limited so much by a requirement for wider channels but by deeper water that flows through these narrow channels. We used a discrete-choice modeling framework and 9 years of roost location data to evaluate the influence of channel-width measures and flow per linear unit of channel width on roost-site selection by Sandhill Cranes. Roost-site selection was influenced by maximum unvegetated channel width and flow per unit length of total unvegetated channel width of all channels. The relative selection ratio increased as maximum unvegetated channel width increased to 131 m for small groups (≤500 cranes) and 275 m for large groups (>5000 cranes), but the ratio was statistically similar across a wide range of maximum unobstructed channel widths. Medium-sized Sandhill Crane groups (501–5000 cranes) were less influenced by in-channel vegetated islands, and these groups selected channels based on wide total unvegetated channel widths. Our results also suggest that flows ≤39.05 m³/s (cms; 1379 cfs) in channels that are 275 m in unvegetated width maximize selection ratios for medium and large crane groups, so flows above this level may not improve Sandhill Crane roosting habitat conditions during the spring migration and staging season within the central Platte River. While Sandhill Cranes stage within the central Platte River valley for a longer time interval in the spring, Whooping Cranes (Grus americana) also use the Platte River as a stopover point. Both species share similar indices for roosting habitat, such as unobstructed channel width and shallow water depths. The results of our investigation could be used to identify a range of flows and channel width configurations expected to generate the highest amount of suitable habitat for Sandhill Cranes roosting along the central Platte River.

Stopover sites provide important forage resources and protection from predators to the Aransas-Wood Buffalo population of Whooping Cranes (Grus americana) as they migrate 4000 km across the Great Plains each spring and fall. Given the Whooping Crane's expansive migration corridor, sensitivity to human disturbance, small population size, and protected status under the Endangered Species Act, it is challenging to gather detailed information regarding the particular forage resources that the cranes exploit at various stopover locations. On 22 March 2018 we observed and photo-documented an adult Whooping Crane consuming at least 5 individual juvenile channel catfish (Ictalurus punctatus) after it landed 100 m in front of our Sandhill Crane viewing blind on the south channel of the Platte River. Using the average exposed culmen length of an adult Whooping Crane for reference, we estimated that the length of the channel catfish ranged from 97 mm to 117 mm. Growth estimates developed from the Lower Platte River suggest that the depredated channel catfish were just over one year old. To the best of our knowledge, our observations represent the first definitive record of a Whooping Crane consuming fish in the Platte River, as well as the first record of a Whooping Crane depredating a channel catfish in the Great Plains. Given the relatively long distances at which Whooping Cranes are generally viewed (≥650 m), small-bodied fish may be a more common prey item during migration than indicated by current scientific literature. Our note demonstrates how wildlife photography and ecotourism can contribute to our understanding of species' natural histories.

Twice annually, the last remaining wild and self-sustaining migratory population of Whooping Cranes (Grus americana) migrates through central Nebraska on its approximately 3900-km journey between Aransas National Wildlife Refuge on the Gulf Coast of Texas and Wood Buffalo National Park in Alberta, Canada. On 27 March 2018, a juvenile Bald Eagle (Haliaeetus leucocephalus) was observed attacking a Whooping Crane on the Loup River near Rockville, Nebraska. The encounter, documented by a private landowner, was forwarded to the U.S. Fish and Wildlife Service as part of the decades-long citizen-science effort undertaken to track and record public sightings of Whooping Cranes during migration. Crane species have few avian predators, and observations of depredations upon these crane species are rare. The Whooping Crane fended off the Bald Eagle, utilizing a “jump-rake” defense; neither species appeared harmed by the clearly aggressive interaction. The episode was reflective of recent observations of Bald Eagles depredating Sandhill Cranes on the Platte River during the spring migration. To our knowledge, this is the first description in scientific literature of a Bald Eagle attacking a Whooping Crane from the Aransas-Wood Buffalo population.

Over 80% of the Mid-Continent Sandhill Crane (Antigone canadensis) Population (MCP), estimated at over 660,000 individuals, stops in the Central Platte River Valley (CPRV) during spring migration from mid-February through mid-April. Research suggests that the MCP may be shifting its distribution spatially and temporally within the CPRV. From 2002 to 2017, we conducted weekly aerial surveys of Sandhill Cranes staging in the CPRV to examine temporal and spatial trends in their abundance and distribution. Then, we used winter temperature and drought severity measures from key wintering and early migratory stopover locations to assess the impacts of weather patterns on annual migration chronology in the CPRV. We also evaluated channel width and land cover characteristics using aerial imagery from 1938, 1998, and 2016 to assess the relationship between habitat change and the spatial distribution of the MCP in the CPRV. We used generalized linear models, cumulative link models, and Akaike's information criterion corrected for small sample sizes (AICc) to compare temporal and spatial models. Temperatures and drought conditions at wintering and migration locations that are heavily used by Greater Sandhill Cranes (A. c. tabida) best predicted migration chronology of the MCP to the CPRV. The spatial distribution of roosting Sandhill Cranes from 2015 to 2017 was best predicted by the proportion of width reduction in the main channel since 1938 (rather than its width in 2016) and the proportion of land cover as prairie-meadow habitat within 800 m of the Platte River. Our data suggest that Sandhill Cranes advanced their migration by an average of just over 1 day per year from 2002 to 2017, and that they continued to shift eastward, concentrating at eastern reaches of the CPRV. Climate change, land use change, and habitat loss have all likely contributed to Sandhill Cranes coming earlier and staying longer in fewer reaches of the CPRV, increasing their site use intensity. These historically unprecedented densities may present a disease risk to Sandhill Cranes and other waterbirds, including Whooping Cranes (Grus americana). Our models suggest that conservation actions may be maintaining Sandhill Crane densities in areas that would otherwise be declining in use. We suggest that management actions intended to mitigate trends in the distribution of Sandhill Cranes, including wet meadow restoration, may similarly benefit prairie- and braided river–endemic species of concern.