14. LIFE BELOW WATER

As Coastal Habitat Shrinks, Scientists Take Inspiration from Surfing Shorebirds

As Coastal Habitat Shrinks, Scientists Take Inspiration from Surfing Shorebirds
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As Coastal Habitat Shrinks, Scientists Take Inspiration from Surfing Shorebirds  National Audubon Society

As Coastal Habitat Shrinks, Scientists Take Inspiration from Surfing Shorebirds

Shorebirds Find Refuge on Floating Roosts Amidst Habitat Loss

On a bright November day in Baja California, Mexico, biologist Julian Garcia-Walther crouched in the cordgrass of a marsh, his face pressed to a scope. He’d spent all morning on the edge of Guerrero Negro Lagoon on the lookout for shorebirds. Down on the lagoon’s mudflats, where the birds spend all day foraging for invertebrates, his team had set traps to catch and mark the birds with GPS tags.

But the team had no luck, and now a spring tide was rolling in—one of the highest of the year, with waters six feet above low tide levels. Garcia-Walther expected to see the birds do what they normally do: As seawater covered the flats, they’d retreat to roost in the marshlands and desert landscape that wasn’t inundated. Today, however, he saw something unusual—the birds didn’t appear to be moving to higher ground, and they seemed to be bobbing gently back and forth as if floating on water.

Adapting to Changing Habitat

Nonplussed, he zoomed in. “When I looked closer, I saw that they were drifting with the tide,” says Garcia-Walther, who works for the conservation nonprofit Pronatura Noroeste.

Instead of roosting among the cordgrass, Red Knots, Short-billed Curlews, Red-breasted Sandpipers, and Snowy Plovers were congregating atop floating mats of seagrass, using them as makeshift rafts. Bewildered, Garcia-Walther returned to the lagoon over the following weeks. As the tides waned with the moon’s cycle, the birds returned to their normal roosts. But a month later, he saw it again: “They were drifting along, totally oblivious that they were on a boat,” he says.

The birds, he realized, might be adapting to a lack of ideal roost sites. Typically, shorebirds roost on dunes or rocky outcroppings that are hidden from predators, undisturbed by human development, and close to foraging sites. But the high tides, likely compounded by rising sea levels, had inundated many of those safe locations. The floating eelgrass was a great hack—it allowed the birds to stay close to the mudflats where they feed and far out of reach of predators.

Loss of Habitat and Conservation Efforts

Loss of shorebird habitat isn’t just a problem during spring tides. In Guerrero Negro, as aquaculture, roads, and seawalls have impinged on roost sites, scientists have seen thousands of shorebirds abandon areas where they used to roost. It’s a trend scientists are seeing worldwide, says Bryan Watts, a conservation biologist at the College of William and Mary who helped launch the Shorebird Roost Registry, a project that compiles key roost locations throughout the Americas to enable their protection and management.

In South Carolina and Georgia, where Watts has conducted research, he sees rising sea levels washing away sandbars and human recreation—from picnics to off-road vehicles—scaring shorebirds away from dunes. “The shorebirds are backed further and further into a corner,” Watts says. He observes them flying 20 or more miles each day between isolated roosts and mud flats, wasting valuable energy. Because many shorebirds migrate thousands of miles twice a year, from the Arctic to as far south as Chile and Peru, every calorie counts, he says.

Artificial Roosts as a Solution

Inspired by the shorebirds themselves, scientists are now experimenting with the idea of building artificial roosts to help the birds find a safe space to rest. But because it’s hard to harness swaths eelgrass, Chris Purnell, wetland bird program manager for BirdLife Australia, found the next best thing: floating oyster bags, which are inexpensive mesh sacks widely used in aquaculture.

Sharp-tailed Sandpipers at a Floating Roost Trial site in Port Philip Bay, Australia. Foto: Chris Purnell

He thought of the idea while doing restoration work in South Korea’s Geum Estuary, where 20 species of shorebird refuel and recuperate on their long journey south from the Arctic. In 2006, a seawall had been built around the estuary, inundating the mudflats and leaving no space for shorebirds to roost. “You saw tens of thousands of birds circling around looking for a roost site,” Purnell says.

While brainstorming low-impact solutions, Purnell remembered seeing flocks of Red Knots congregating on mats of floating eelgrass years earlier. Not only was the eelgrass close to foraging sites and out of harm’s way, it was “chock a block” with tasty invertebrates and allowed the birds to stay cool on scorching days. He realized that floating oyster bags might provide similar benefits.

BirdLife Australia’s Floating Roost Trial, which took place in 2019, involved installing lines of oyster bags at three sites: Korea’s Geum Estuary, and Australia’s Hunter Estuary and Western Port Phillip Bay. At Geum Estuary, the effect was instantaneous. As soon as volunteers waded out of the water, shorebirds descended—as many as 54 onto a single bag. During the trial, they reported, 18 species, including the critically endangered Eastern Curlew, benefitted from the artificial roosts.

Watts, who was not involved in the work, says artificial floating roosts are an innovative solution with potential for success. The main benefit, as he sees it, is how easy it is to install them close to foraging sites, helping shorebirds save energy. “They’re in a precarious situation,” Watts says. “Providing new ro

SDGs, Targets, and Indicators

1. Which SDGs are addressed or connected to the issues highlighted in the article?

  • SDG 14: Life Below Water – The article discusses the impact of rising sea levels and human development on shorebird habitats, highlighting the need for conservation efforts to protect these habitats.
  • SDG 15: Life on Land – The article focuses on the loss of shorebird habitat and the need to provide safe spaces for these birds to rest and roost.

2. What specific targets under those SDGs can be identified based on the article’s content?

  • SDG 14.2: By 2020, sustainably manage and protect marine and coastal ecosystems to avoid significant adverse impacts, including by strengthening their resilience, and take action for their restoration in order to achieve healthy and productive oceans – The article emphasizes the need to protect shorebird habitats from the impacts of rising sea levels and human development.
  • SDG 15.5: Take urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity, and, by 2020, protect and prevent the extinction of threatened species – The article highlights the loss of shorebird habitats due to human development and the need to provide artificial roosts as a solution.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

  • Indicator for SDG 14.2: Proportion of coastal and marine areas that are protected, by type (e.g., percentage of protected shorebird habitats)
  • Indicator for SDG 15.5: Number of threatened species protected and prevented from extinction (e.g., number of shorebird species benefiting from artificial roosts)

Table: SDGs, Targets, and Indicators

SDGs Targets Indicators
SDG 14: Life Below Water 14.2: By 2020, sustainably manage and protect marine and coastal ecosystems to avoid significant adverse impacts, including by strengthening their resilience, and take action for their restoration in order to achieve healthy and productive oceans Proportion of coastal and marine areas that are protected, by type (e.g., percentage of protected shorebird habitats)
SDG 15: Life on Land 15.5: Take urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity, and, by 2020, protect and prevent the extinction of threatened species Number of threatened species protected and prevented from extinction (e.g., number of shorebird species benefiting from artificial roosts)

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Fuente: audubon.org

 

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