Combining Tracking and Remote Sensing to Identify Critical Year-Round Site, Habitat Use and Migratory Connectivity of a Threatened Waterbird Species

Abstract

We tracked 39 western flyway white-naped cranes (Antigone vipio) throughout multiple annual cycles from June 2017 to July 2020, using GSM-GPS loggers providing positions every 10-min to describe migration routes and key staging areas used between their Mongolian breeding and wintering areas in China’s Yangtze River Basin. The results demonstrated that white-naped cranes migrated an average of 2556 km (±187.9 SD) in autumn and 2673 km (±342.3) in spring. We identified 86 critical stopover sites that supported individuals for more than 14 days, within a 100–800 km wide migratory corridor. This study also confirmed that Luan River catchment is the most important staging region, where white-naped cranes spent 18% of the annual cycle (in both spring and autumn) each year. Throughout the annual cycle, 69% of the tracking locations were from outside of the currently protected areas, while none of the critical staging areas enjoyed any form of site protection. We see further future potential to combine avian tracking data and remote-sensing information throughout the annual range of the white-naped crane to restore it and other such species to a more favourable conservation status.

Breeding and migration performance metrics highlight challenges for White-naped Cranes

“…Since WNC breeding, wintering, and staging grounds stretch across a huge area and many countries, this can only be achieved through collaborative research efforts. Many of the WNCs key sites are unprotected 53 – 55 including breeding sites, which our study indicates have decreased in suitability and may be key in explaining the species’ population decline. Though we did not link habitat conditions directly to survival in this study, conditions were clearly associated with breeding performance and therefore likely long-term productivity.…”

“…These climatic processes in combination with increasing human activity are expected to result in further degradation of wetlands in the region. Over the past 50 years, many of the region’s wetlands have been converted to agricultural land 75 – 77 , reducing breeding habitat but also opening up alternative foraging opportunities for WNCs 53 , 78 . The use of these fields by cranes is causing human-wildlife conflicts due to real or perceived crop damage in many places 26 , 77 , 79 – 83 .…”

“…The clustering of fixes identified 88 location clusters outside the breeding and wintering grounds. Finally we only considered clusters where birds stayed a minimum of two days to identify 31 true stopover sites 53 .…”

“…For testing the migration duration and number of stops, we used the mean of March and April environmental data for the Luan River catchment (stopover) for northbound and mean of October and November data for southbound migration. This Luan River catchment (hereafter Luan) was previously recognised as the major stopover in a number of studies 53 – 55 . To test for potential anthropogenic impacts on migration, we included annual human population density estimates as an additional covariate for testing departure date, migration duration, and number of stopovers.…”

Satellite Tracking Reveals an Exploration of Migration Routes by White-Naped Cranes (Antigone vipio)

“…From 1991From to 1993 individuals in Japan and Russia were tracked to present the migration routes, stopover sites, and migration patterns (Higuchi et al 1992(Higuchi et al , 1996(Higuchi et al , 2004Ueta 2002). By the 2020s, a large amount of longterm tracking data revealed that the upper reaches of the Luanhe River in Inner Mongolia, China, comprised the most important stopover area for the western population of White-naped Cranes (Lang et al 2020;Batbayar et al 2021).…”