Florida Bay Spoonbills Struggle with Sea Level Rise During Nesting Season

Birds tell us when climate conditions change too much or too quickly. Scientists at the Everglades Science Center (ESC) have studied and monitored Roseate Spoonbills in Florida Bay since the 1930s, and once again noted their difficulty fledging chicks, this time because of higher-than-usual water levels in the 2021-2022 breeding season.

The Roseate Spoonbill is considered an umbrella species and an indicator of overall Everglades and Florida Bay health. ESC monitors five nesting regions throughout Florida Bay based on the distance to their primary foraging habitat. Every December, the team begins its regular surveys to monitor nesting activity, continuing through May.

“Spoonbills require water depths no greater than 20 cm to forage effectively due to their body size,” explains Alexander Blochel, Senior Biologist at ESC. Though they can forage at 20 cm, he notes that during breeding season they really need levels to drop to 13 cm or less so that prey fish become concentrated. Lower water levels create high-density foraging zones, allowing the birds to find enough food to feed their hungry chicks.

During the 2021-22 nesting season, staff surveyed 64 keys in Florida Bay and three nearby mainland Everglades sites. Nests were considered successful if at least one chick reached 21 days of age. The team counted 158 nests throughout the 2021-22 nesting season, but only 54 reached that critical 21 day threshold when the chicks begin to move about on their own. To get a sense of how poor these numbers are, it is important to note that in the previous nine nesting seasons, total nests ranged from 191 up to 367 nests, and for Roseate Spoonbills to maintain a stable population each nest must fledge at least one chick.

Our Audubon researchers also noted that nesting began very late this year (the end of January), but even that late start was not enough to create the conditions needed to successfully feed their chicks until mid-March. Water levels may have dropped, but they remained low for fewer days, further shortening the nesting season.

While these numbers seem bleak, many spoonbills have moved to different foraging and breeding areas throughout Florida and are doing quite well. For example, Audubon Florida staff monitoring the Richard T. Paul Alafia Bank Bird Sanctuary in the Tampa Bay region, which is leased from and managed in collaboration with the Mosaic Company and Port Tampa Bay, counted nearly 100 Roseate Spoonbill chicks that fledged from approximately 50-75 nests nearby.

At Audubon, we know the importance of protecting a variety of habitats for Roseate Spoonbills and other vulnerable wading bird species as climate change and development continue to impact their nesting, breeding, and feeding grounds. Using cutting-edge technology and decades of long-term research, we listen closely to what the Roseate Spoonbills are telling us — and use this information to protect them now and into the future.

This article was published in the Fall 2022 State of the Everglades report.

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