Friday, September 22, 2017

Tree islands provide protection for coastal egrets during Hurricane Irma

What do you think Reddish Egrets living along the Gulf Coast of Florida did during Category 4 Hurricane Irma?  If you’ll recall, we have been tracking six of these birds for several years with GPS-enabled satellite transmitters. Five were outfitted with these amazing devices on and near Sanibel Island’s J. N. “Ding” Darling National Wildlife Refuge; one was tagged near a remote shore in Dixie County, Florida.

San Carlos (left) and an unmarked Reddish Egret at San Carlos Bay -Bunche Beach Preserve.
Photo credit Teresa Hedden 2017.
Think about Reddish Egrets. Picture these one-and-a-half pound bundles of feathers bobbing and weaving in coastal shallows and lofting gently over the reclining mangrove forest. Now imagine winds that can lift roofs off houses and storm surges that can over-wash these placid mangroves. How many of these birds do you think survived Hurricane Irma? If you’re like us, you probably did not feel optimistic as Irma played out, even wondering if any of these birds could have lived to keep telling us their stories.

Well, thanks to marvelous technology and the generosity of many organizations and individuals, ARCI has the answer for you: Every one of them. That’s right. Not one of our tracked Reddish Egrets succumbed to Irma’s terrible beating.  And, they all survived while hunkering down in the places we’ve come to know as their favorite roosts, embedded within the small coastal landscape that includes all their favorite feeding places.

As Hurricane Irma approached, Ding#1 and Ding#2, tagged in June and October of 2014 respectively, were near the Wildlife Drive, J. N. “Ding” Darling National Wildlife Refuge, on Sanibel Island. The tracking data revealed that they were using roost sites on the small islands to the east of the observation tower, plus the interior mangrove ponds that were likely granted some protection from the wind. 

Bunche Beach, ARCI's
only tagged white-morph
Reddish Egret. Photo credit
Janet Kirk 2016.
The two mainland Reddish Egrets, San Carlos and Bunche Beach tagged in January 2016, moved among the small creeks rising in the “uplands” (it’s all relative) bordering the shoreline and extensive foraging flats of the San Carlos Bay-Bunche Beach Preserve that end abruptly at the municipal boundary of densely-developed Fort Myers Beach.

Darling, tagged near the Wildlife Drive in January 2016, spent the worst part of the storm just inside the dense mangrove stand on the south end of Pine Island. Shortly after the storm abated, he flew to the east side of Sanibel, one of his typical foraging areas.

Our sixth Reddish Egret, Hagen, tagged in the Big Bend Wildlife Management Area of Dixie County in December, 2014, remained for two days on one of his habitual roosting islands, which is three miles south of his core foraging area. After the storm passed, he resumed his regular routine.

Obviously these birds endured the strong winds, heavy rains, and menacing storm surge associated with Hurricane Irma.  Their inland flights documented by telemetry early in the storm may have resulted from a storm surge forcing them to find higher ground. Foraging areas days later were in isolated ponds away from the coast, which probably were shallow enough to permit feeding. Foraging conditions may have been enhanced in such sites because over-wash would have introduced fish that became entrapped as the water receded.

We hope that other birds, including Reddish Egrets and all the other species that grace Florida’s skies, did as well as these individuals that share their secrets with us every day, teaching us – electronically – what we need to know to help protect their future.