On High Ground: Why Black-necked Cranes Are Roosting on Land
New research reveals how a high-altitude crane species is changing its nocturnal behaviour in response to vanishing wetlands and human disturbance
Unexpected behaviour in a highland crane
Black-necked Cranes (Grus nigricollis) have long been known to roost in shallow water at night - a behaviour thought to offer protection from predators and disturbance. But a new study led by Xinlei Hou and colleagues, published in Ecology and Evolution, reveals a growing tendency for these cranes to roost on land in parts of their eastern wintering range on the Yunnan-Guizhou Plateau. This terrestrial roosting behaviour, observed in some areas for decades but rarely studied in depth, is now confirmed to be more widespread and complex than previously recognised.
The team used GPS-GSM trackers fitted to 14 cranes between 2015 and 2022, alongside high-resolution satellite imagery, to identify and characterise nocturnal roost sites across nine wintering locations. Their findings suggest that land-based roosting is not simply a fallback strategy when water is unavailable, but a dynamic, sometimes preferred option depending on terrain, proximity to feeding areas, and possibly even individual personality traits.
Why cranes abandon the water
Across the study sites, 78% of crane nights were spent roosting in shallow water, but nearly 20% occurred on land - a significant figure for a species traditionally considered wetland-dependent. The proportion of terrestrial roosting varied widely by location and was strongly correlated with the size of local water bodies. In places like Yongshan and Ludian, where wetlands have degraded or disappeared, cranes exclusively used terrestrial roosts.
However, even in areas with abundant wetlands, some individuals still opted for land-based roosts. This was notably the case for two tracked cranes at Dashanbao and Caohai. Such decisions appear to reflect not just environmental pressures but behavioural flexibility - and perhaps personality - with some birds displaying a consistent preference for roosting on upland ridges and terraces closer to feeding areas.
Safety from below: a shift to the highlandsThe study reveals that Black-necked Cranes favour highland terrain for terrestrial roosting, including mountain tops, ridges, and uphill terraces, while avoiding valleys and lowland flats. These elevated areas offer better visibility, reduced predator access, and flatter ground suitable for take-off and landing. In several cases, cranes roosted close to roads or settlements but remained protected by inaccessible terrain.
Yet roosting on land appears to come at a cost. Cranes sleeping on high ground were 14 times more likely to make significant nocturnal movements - suggesting higher levels of disturbance or a greater need to reposition during the night. This contrasts sharply with the near-total stability observed at water-based roosts, where movement was minimal.
Conservation implications and recommendationsThe authors argue that terrestrial roosting by Black-necked Cranes is best understood as a behavioural adaptation to changing habitats - especially the loss of shallow wetlands and increased human pressure. They stress that while the birds exhibit a notable capacity for flexibility, this should not distract from the urgent need to conserve and restore wetland habitats.
Key conservation recommendations include: protecting existing large wetlands; restoring and connecting smaller fragmented wetlands; improving monitoring of terrestrial roosts using infrared cameras and weather stations; and controlling free-ranging dogs, which pose a significant disturbance and predation risk to land-roosting cranes.
This study highlights the importance of nocturnal ecology in understanding bird conservation needs. By leveraging modern tracking technologies, the researchers have provided rare insights into a poorly known behaviour that may hold the key to how one of the world’s highest-dwelling cranes copes with a rapidly changing landscape.
June 2025
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