Image: Mattea Taylor
Shorebirds are a fascinating group of mostly coastal birds. Fairly small, grey-brown, and skittish, they’re not the type you’d expect to fly tens of thousands of kilometres from Australia to the farthest parts of Russia and Alaska and back every year. These summer-chasing birds hold world records for their flying feats (https://birdlife.org.au/news/bar-tailed-godwit-breaks-record/) and are considered extreme endurance athletes.
To make these incredible journeys, shorebirds spend the Australian summer eating as much as they possibly can, storing all this energy as fat, which they then burn rapidly as they speed north to breed. Most of their food lives in the mud—things like crabs, shrimp, snails, and polychaete worms—which can only be accessed during low tide, when the mud is exposed.
During high tide, shorebirds often have no choice but to find somewhere safe to rest until the tide recedes and they can feed again. These “roost” sites are often beaches or saltmarshes, and sometimes piers or oyster poles. Shorebirds tend not to like roosting near trees or tall shrubs. It’s thought that this is because trees block their view and could leave them more vulnerable to predation.
In Australia, the main predators of shorebirds are birds of prey like eagles and kites that patrol the skies around the shores. Shorebirds kick their flight response into overdrive when they feel threatened, using their Top Gun-esque flying skills to evade capture. This is termed a disturbance (or alarm) flight. Flocks take off quickly, together, moving in unison, rapidly twisting, turning, rising, and falling. It is quite a mesmerising and fantastic sight to witness, and photographers often love to capture such moments.
Image: Mattea Taylor
Unfortunately, it also burns a lot of the energy that the shorebirds have been building up for migration. Too many disturbance flights and the shorebirds might not have enough energy to complete their migration journey. This could mean they might not survive the journey, might not have enough energy to breed successfully once they arrive up north, or might not leave for migration that year at all.
Shorebirds aren’t only disturbed by birds of prey. They react to anything they think might be a threat, including people, dogs, and noisy machines like boats or planes. Adding a human element of disturbance to the natural disturbance already present can magnify the effects on shorebirds and make it more likely that they won’t have the energy they need to successfully migrate. When around shorebirds at high tide, it is important to move slowly and give them a wide berth to respect their space and their need for rest.
This topic of disturbance forms part of my PhD research in the Hunter Estuary, NSW. I observed shorebird behaviour at various sites during high tide, recording the levels of human and natural disturbances and shorebird flight responses to determine the extent to which shorebirds are disturbed in this estuary. That’s for another blog. Here, I wanted to highlight the importance of giving resting shorebirds space so they can preserve their energy for another day. Their quick aerobatic flights may look fantastic but could potentially be fatal.
Author: Mattea Taylor
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