Wading into Global Warming

Eye-catching and iconic, wading birds warm the heart of even the coldest curmudgeon. As their name suggests, these long-legged birds forage by wading through water. In North America, South Florida is the most important breeding area for these winged creatures. A range of unique species makes their homes here including roseate spoonbills, snowy egrets, and great white herons; an occasional American flamingo even makes a cameo from time to time. As top predators, they reflect the health and viability of the Everglades, a vast set of wetlands, forests, and other ecosystem types covering the bottom half of the state. Regrettably, under the looming tide of global warming, wading birds face a number of threats.

A Brief History of Water and Wading Birds

Unfortunately, wading birds have already declined by up to 90% since the 1930s and 1940s in South Florida. What’s fueling such a dramatic decline? One major driving force lies in the watery habitat they call home, and the numerous changes in hydrology that occurred in the Everglades over the last century. Attempts to drain the Everglades for development and agriculture destroyed nearly half of the original habitat. Further, the construction of canals and levees reduced freshwater flow, which in turn, harmed wading birds’ habitat and prey availability.

These changes mattered since wading birds are highly attuned to water levels, especially when they’re breeding in the dry season (from November to April in Florida). During this time, water depths that fall to low levels without rising again will concentrate dispersed prey in the deeper areas of the landscape. However, if this doesn’t happen, it makes it difficult for them to capture enough prey fish and crayfish to feed their rapidly growing chicks. During the wet season (from May to October), when water levels rise, these prey items disperse into shallower marshes to reproduce and avoid predation. Sadly, a lack of abundant food can lead to nest failure and abandonment.

Wading Birds under Global Warming

With climate change sweeping across their habitat like a steamy wave, the future promises no reprieve either. In South Florida, climate change could lead to range shifts, alterations in reproduction and survival, and changes in the timing of important events like breeding or migration.

Here are some of the changes predicted for South Florida’s wading birds under global warming:

• Sea level rise could alter and eat up coastal and low-lying wetland habitats.
• Extremes in weather conditions could threaten chicks in the nest.
• Drier conditions could reduce the abundance of wading birds’ prey.
• Warmer temperatures could help invasive fish species spread and potentially compete with wading birds’ native prey species.
• Drier conditions could harm wading bird reproduction.
• Stronger tropical storms could damage habitats and kill wading birds.
• Several species of wading birds have expanded their ranges north, and many other species may soon follow suit.

Restoration to the Rescue

Despite this gloomy outlook, all hope isn’t lost. In the face of climate change, restoration of the natural flows and patterns of water through the Everglades is predicted to benefit wading birds. For instance, restoration efforts will help ensure deeper water levels than they would be otherwise during both seasons. However, many areas are still likely to be drier than they are now.

Other benefits of restoration for wading birds under global warming include:

• Slowing the impacts of sea level rise and saltwater intrusion around the coast.
• Protecting habitats and improving population resiliency.
• Boosting wading bird prey production.
• Enhancing wading birds’ breeding efforts.

Want to learn more about wading birds?

Audubon’s guide outlines the impacts of climate change on each avian species, including wading birds.

The South Florida Water Management District creates an annual report on wading birds’ breeding efforts.

Learn more about Everglades restoration at Florida Audubon or the Everglades Foundation.

Check out my colleague and photographer extraordinaire, Dr. Mark Cook’s photographs here or on Instagram.