Whooping Crane (Grus americana) Family Consumes a Diversity of Aquatic Vertebrates During Fall Migration Stopover at the Platte River, Nebraska

Abstract

The Aransas-Wood Buffalo population of Whooping Cranes (Grus americana) migrates approximately 4000 km through the central Great Plains biannually, between their breeding and wintering grounds. Whooping Cranes depend on stopover sites to provide secure resting locations and the caloric resources necessary to complete their migration, such as the USFWS-designated critical habitat area in the Central Platte River Valley (CPRV) of Nebraska. This area includes braided river habitat characterized by low-elevation and submerged sandbars, which provide important roosting and foraging opportunities for migrating Whooping Cranes. We used long-range photography, videography, and behavioral scan sampling to document forage items consumed by Whooping Cranes during an 11-day stopover in this area during the fall of 2019. We identified 3 adult-plumage Whooping Cranes and 1 colt consuming 16 individual vertebrates of at least 6 different species during the stopover. In total, we documented Whooping Cranes consuming 7 Channel Catfish (Ictalurus punctatus), 5 ray-finned fish (Actinopterygii), 1 sunfish (Centrarchidae), 1 carp/minnow relative (Cypriniformes), 1 perch relative (Percidae), and 1 Leopard Frog relative (Lithobates sp.). We estimated prey item lengths using the average exposed culmen measurements for adult Whooping Cranes and approximated their nutritional value using log-transformed length–weight regression equations with taxon-specific intercepts and slopes from secondary data sources. We estimated that aquatic vertebrate forage made up a significant portion of Whooping Crane daily energy requirements and provided substantial amounts of calcium, phosphorus, and protein not present at high levels in waste grains also consumed during migration. Additionally, we documented territorial behavior by adult Whooping Cranes during migration and evidence of adults teaching their colt to forage. Our study demonstrates the utility of photography and videography to natural history research and indicates that aquatic vertebrates may be a relatively regular part of Whooping Crane diet in the CPRV.