Sandhill crane roost selection, human disturbance, and forage resources

Abstract

Sites used for roosting represent a key habitat requirement for many species of birds because availability and quality of roost sites can influence individual fitness. Birds select roost sites based on numerous factors, requirements, and motivations, and selection of roosts can be dynamic in time and space because of various ecological and environmental influences. For sandhill cranes (Antigone canadensis) at their main spring‐staging area along the Platte River in south‐central Nebraska, USA, past investigations of roosting cranes focused on physical channel characteristics related to perceived security as motivating roost distribution. We used 6,310 roost sites selected by 313 sandhill cranes over 5 spring migration seasons (2003–2007) to quantify resource selection functions of roost sites on the central Platte River using a discrete choice analysis. Sandhill cranes generally showed stronger selection for wider channels with shorter bank vegetation situated farther from potential human disturbance features such as roads, bridges, and dwellings. Furthermore, selection for roost sites with preferable physical characteristics (wide channels with short bank vegetation) was more resilient to nearby disturbance features than more narrow channels with taller bank vegetation. The amount of cornfields surrounding sandhill crane roost sites positively influenced relative probability of use but only for more narrow channels <100 m and those with shorter bank vegetation. We confirmed key resource features that sandhill cranes selected at river channels along the Platte River, and after incorporating spatial variation due to human disturbance, our understanding of roost site selection was more robust, providing insights on how disturbance may interact with physical habitat features. Managers can use information on roost‐site selection when developing plans to increase probability of crane use at existing roost sites and to identify new areas for potential use if existing sites become limited. © 2016 The Wildlife Society.

Diurnal habitat selection of migrating Whooping Crane in the Great Plains

“…associated with water-based land-cover classes may decrease the aversion of roads and other disturbance features on the landscape, whereas activities within other land-cover classes may increase alertness and aversion to roads. Pearse et al (2017b) demonstrated that Sandhill Crane (Antigone canadensis) is less sensitive to disturbance in higher quality roosting habitat that has lower bank vegetation and wider channels within the central Platte River. It is possible that North American Gruidae species perceive greater Fig.…”

Temporospatial Shifts in Sandhill Crane Staging in the Central Platte River Valley in Response to Climatic variation and Habitat Change

“…Faanes and Le Valley (1993) also showed that Sandhill Crane roosting densities were increasing in areas with relatively abundant remaining wet meadow habitat. Pearse et al (2017) demonstrated that the probability of Sandhill Cranes roosting in a portion of the river is related to the amount of cornfield nearby only when channels are relatively narrow; however, their study did not evaluate the impact of lowland grasslands on roosting distributions. Anteau et al (2011) found that the use of cornfields by cranes increased with the quantity of wet grassland habitat within 4.8 km.…”

“…However, the impact of these efforts on the roosting distribution of Sandhill Cranes remains largely unexamined. Several studies investigated Sandhill Crane roosting habitat in the CPRV and generally found that Sandhill Cranes prefer channels wider than 150 m, bank vegetation <1.5 m tall, and shallow water depths (<20 cm); they also prefer a lack of human disturbance, including roads, bridges, and structures (Krapu et al 1984, Iverson et al 1987, Folk and Tacha 1990, Norling et al 1992a, Davis 2001, Pearse et al 2017. In addition to being an important predictor of Sandhill Crane roosting habitat use, channel width is indicative of broader riverine habitat features in the CPRV, including channel morphology, hydrology, and sinuosity, that can also impact Sandhill Crane habitat suitability (Schumm 1963, Williams 1978, Johnson 1994, Kinzel et al 2009, Horn et al 2012.…”

“…Over 2 decades later, Davis (2003) found that only 25% of the CPRV was wider than 150 m and that these areas contained 90% of the roosting Sandhill Cranes. Pearse et al (2017) recently found that about 60% of the available roosting habitat was less than 100 m in width. Channel width may serve as a broad indicator of habitat quality, yet Sandhill Crane declines have been noted in the western portion of the CPRV even where quality roosting habitat still exists (Buckley 2011).…”

“…In addition to channel characteristics, land cover features also influence Sandhill Crane roosting distributions (Sidle et al 1993, Sparling and Krapu 1994, Pearse et al 2017. Sandhill Cranes require 3 general habitats while in the CPRV: wide channels for roosting, croplands (predominantly cornfields) to meet energetic needs, and wet meadows for protein and other nutrients (Krapu et al 1982).…”