Thursday, April 26, 2018

Our first account of ARCI’s exciting new research on Mangrove Cuckoos in Florida

Mangrove Cuckoo Cross Dike with visible antenna
from a 2-gram satellite transmitter.

Photo by Aaron Kirk

ARCI’s biologists have found that many conservation-related research questions can be answered best by employing some type of tracking technology. Our study subjects, which include birds of various families, sizes, and habitat associations, have benefited from this approach. These include Swallow-tailed Kites, Short-tailed Hawks, Reddish Egrets, White-crowned Pigeons, Crested Caracaras, Great White Herons, Peregrine Falcons, Snail Kites, Southeastern American Kestrels, and Magnificent Frigatebirds. Although telemetry’s use is limited somewhat by the essential permitting requirement that the equipment not exceed 3% of a tagged bird’s body weight, there has been no shortage of imperiled birds large enough to carry the best-available tracking devices. Of course, this still leaves data needs unaddressed for the many species of smaller birds requiring conservation action. 

Fortunately, the ongoing development of smaller and more sophisticated telemetry devices has allowed us to keep gradually unraveling the behavioral secrets of smaller and smaller birds. One such species, the Mangrove Cuckoo, was of great interest to ARCI’s researchers in 2015 when Microwave Telemetry Inc. (MTI), our long-standing source for satellite-telemetry devices, asked us to test their prototype 2-gram solar-powered transmitter – the smallest satellite-tracking device ever developed. No one has ever determined the wintering destinations of Florida’s breeding Mangrove Cuckoos, or whether they migrate at all. This is vitally important information for this species, which is thought to be declining across its small global range. To make such a project possible, MTI donated four of their 2-gram transmitters to ARCI (they now sell for $4,500 each).

At the time, ARCI already had been using MTI’s larger satellite transmitters with great success to study the movements and ecology of Reddish Egrets in Florida, including a population on the J. N. “Ding” Darling National Wildlife Refuge (NWR), Sanibel Island, Florida. This declining species is one of the relatively few birds considered seriously threatened by the Florida Fish and Wildlife Conservation Commission. The Ding Darling NWR has been a very receptive and supportive site for our egret studies, and they were particularly interested in seeing ARCI conduct Mangrove Cuckoo research to expand on results of prior cuckoo research and to tackle questions about seasonal movements and nesting ecology using this amazing tracking tool.

From August 2015 to February 2018, we safely deployed MTI’s four donated 2-gram satellite transmitters on Mangrove Cuckoos inhabiting Ding Darling NWR. Although transmitter lifespans have been relatively short (likely due to the vulnerability of the tiny radios and their fragile antennas), we received over 12 cumulative months of reliable data from the first three birds. Virtually all the satellite fixes for these three birds were on Sanibel Island, suggesting that long-distance migration might not be occurring.

Mangrove Cuckoo Indigo East just prior to release,
showing the 2-gram satellite transmitter.

The only exception was a movement in early April 2016, at the start of the nesting season, by Indigo East, a bird that had over-wintered on the Refuge after we tagged it the previous November (tracked birds are named after their capture location). In this case, Indigo East quickly traveled six miles north, across a wide channel, and settled in a small area within the mangrove forest along the western shore of Pine Island. Here it remained until we stopped receiving data two months later. Had it moved there to nest?

This intriguing behavior, although inconclusive, suggested that Mangrove Cuckoos wintering on Ding Darling NWR may indeed move elsewhere when it comes time to nest, but the distances may be very short. Was this a rare exception, or is such behavior the rule? Do birds that breed on the Refuge move southward off of Sanibel Island for the winter? How many Mangrove Cuckoos nest on the Refuge, and how productive are they? As is usually the case, new information led to still more questions.

We recently received our most important results to date. Cross Dike, the fourth and final Mangrove Cuckoo we tagged with a donated transmitter (last February, as a wintering bird) made a sudden move northeastward on a track similar to that taken by Indigo East two years before (see Figure 1). Furthermore, both birds moved during the same week in April. The only difference was that Cross Dike traveled an additional six miles across a second channel before settling in the broad mangrove forest on the western shore of Cape Coral - a total of 12 miles from its wintering area on Sanibel.
Figure 1. Early breeding-season movements of two satellite-tracked Mangrove Cuckoos from established winter ranges on Sanibel Island, Florida. Indigo East (white) moved to Pine Island on 6 April 2016 and remained at least until early June, when data transmission ceased. Cross Dike (red) moved to Cape Coral on 12 April 2018, where the bird remains as of this update.

Obviously, we are working with a small sample of tagged Mangrove Cuckoos. However, we now have highly consistent movement data, on fine time and spatial scales, from these two study birds whose tracking periods have bridged the wintering and breeding seasons. This is very exciting!

Given our very exciting recent tracking results for Mangrove Cuckoos from Ding Darling NWR, we are hoping to expand ARCI’s tracking studies of this species both in scope (to include more tracking, plus nest-finding and monitoring) and geography (to other Florida populations, and eventually to Cuba as part of our long-term collaborations with University of Havana faculty and graduate students). At the moment, we are awaiting a decision from Ding Darling NWR’s staff on a proposal they requested for expanding our current Mangrove Cuckoo research on the Refuge.

ARCI is grateful to Microwave Telemetry, Inc., and particularly to Dr. Paul Howey, for their very generous contribution of the essential transmitters for the first phase of the Mangrove Cuckoo study. We also thank Refuge Manager Paul Tritaik for permission and logistic support for conducting this work on the
Ding Darling NWR.  The Refuge staff is dedicated to carefully managing this public conservation area’s diverse and sensitive resources with the best available information. The fundraising and outreach efforts of the Ding Darling Wildlife Society (the Refuge’s illustrious “Friends” organization), and the support of Sanibel donors Judy Samelson and Bill Schawbel, have been instrumental in the project’s success. We also are grateful to ARCI’s universe of followers and supporters for their willingness to share in and support our common mission.

We look forward to updating all of you on our progress, and to sharing what we learn as this exciting project unfolds.

Thursday, February 22, 2018

Happy Tracking Anniversary to a Persistent Jamaican Pigeon!

Ricardo Miller prepares to release Trelawny after a successful tagging.

WOW!  We’ve been tracking Trelawny, an adult, female, White-crowned Pigeon (Patagioenas leucocephala) for 4 years using the smallest satellite transmitter made at the time of its capture, a 5-gram solar unit made by Microwave Telemetry Inc.

A big “Thank You” to ARCI’s collaborators, the Jamaica National Environment and Planning Agency (NEPA), especially Ricardo Miller; and for the assistance of Susan Koenig of the Windsor Research Centre.

All of Trelawny’s days since tagging have been spent within Jamaica’s Trelawny Parrish, on the north central part of the island. She has two focal areas that are about 5 miles apart. Most of the year, she resides in Cockpit Country, inland near the town of Duanvale, where there are plenty of native fruit-bearing trees. Occasionally she comes down to the coastal lowlands to make use of different food sources and to roost near Falmouth.

This bird has persisted through four regulated hunting seasons within Jamaica. The hunting season lasts 6 weeks in August and September and is approved each year by the Prime Minister under the recommendations of the Natural Resources Conservation Authority. All hunters need to obtain a $160 (US) license from the National Environment and Planning Agency (NEPA).

Today we want to recognize her tenacity and all the highly informative data we received from her. Trelawny has been tracked longer than any other White-crowned Pigeon. The next longest was a bird we tracked in Florida for 2.1 years.

ARCI has now satellite tracked 16 White-crowned Pigeons throughout much of their range in the Cayman Islands, Jamaica, Bahamas, Puerto Rico and Florida for a multi-partner research project entitled “Seasonal movements of White-crowned Pigeons tracked by satellite telemetry: Identifying trans-national threats, management needs, and conservation opportunities."

Source: The Cornell Lab of Ornithology, All About Birds
The White-crowned Pigeon is widely distributed throughout the Caribbean, but the species is threatened by habitat loss, poaching, and, in some countries, harvest regulations that are not based on scientific data. With satellite telemetry, we are informing wildlife managers of seasonal changes in distribution, identifying manageable threats, and documenting the need for concerted conservation planning across national boundaries. 

You can follow the movements of the tagged White-crowned Pigeons through a link on our website:

Tuesday, December 5, 2017

Taking the Breezy Way Out

With the ability to stay aloft over water for weeks at a time, we can assume that Magnificent Frigatebirds usually fare well when displaced by hurricanes. We observed this survival strategy with one of our own GPS/satellite-tracked Magnificent Frigatebirds in September 2017 as Hurricane Irma moved northward up peninsular Florida’s Gulf coast.

ARCI has been collaborating for seven years with the U.S. Fish and Wildlife Service’s Florida Keys National Wildlife Refuge Complex in deploying satellite/GPS tracking units on Magnificent Frigatebirds captured at winter roosts in the Florida Keys and at the only U.S. nesting location, a colony of just 100 pairs in the Dry Tortugas. This information has helped us determine for the first time where the wintering birds breed, where the breeding birds overwinter, patterns of seasonal movements, fidelity to roost sites, and survivorship.

Dry Tortugas Male was captured on 15 May, 2013, as a breeding bird and tracked every day for the last 4.5 years!  You can follow his movements, along with those of all the other tagged birds monitored as part of ARCI’s research, by visiting this page on ARCI’s website.

Unlike the non-breeding Magnificent Frigatebirds that roost and feed within the lower Florida Keys and nest in the western Caribbean (Yucatan Peninsula of Mexico and Cuba), the breeding birds from the lone U.S. colony on the Dry Tortugas stay close to the coast of peninsular Florida when not bound by nesting obligations.

As we documented over the previous 4 years, the Dry Tortugas male had been spending the non-breeding season, since 10 June 2017, foraging out over the Gulf of Mexico from small mangrove islands that line peninsular Florida’s western coast. At 6:45 pm on 8 September, Dry Tortugas male was near the mouth of Crystal River about 38 miles north of Irma’s eye as it moved northward across the Florida Straits. About 22 hours later, Irma made landfall near Naples, Florida, and continued northward along Florida’s west coast.

By this time, the Dry Tortugas male was almost certainly being exposed to winds of at least 55 MPH.  When it became impossible to grip the vegetation in its mangrove-forest roost, this bird took to the sky to glide downwind to safety as Hurricane Irma passed.

Over the next 2.5 hours, Dry Tortugas male used Irma’s strong winds to fly almost 160 miles southwest out into the Gulf of Mexico and away from the severe winds generated close to storm’s eye. Here, he was even closer to the hurricane, 120 miles from the eye. In 6 hours, Dry Tortugas male had traveled an additional 110 miles southwest before turning eastward on favorable tailwinds that carried him to Pine Island in Lee County, Florida. His journey from Crystal River to Pine Island was completed in a little more than 9 hours. He wasted little time before heading north back to his wintering area near Crystal River.

Overall, this Magnificent Frigatebird’s hurricane detour was a 650-mile round-trip that lasted a little over 2 days.  A mere inconvenience?  A free ride?  In any case, a very different strategy for outliving a hurricane compared with the behavior of most of the other birds whose movements we have documented with remote telemetry.

Dry Tortugas Male's movements as he evaded Hurricane Irma in September 2017.

Monday, October 2, 2017

A resilient and now famous Short-tailed Hawk

ARCI has been studying Short-tailed Hawks, one of Florida’s rarest raptors, since 1999. These stunning raptors are sometimes overlooked because of their secretive behaviors. They hunt from high in the sky, often disguising themselves in a kettle of vultures before diving down to surprise avian prey. They like to nest in forested strands often associated with water; however, they have recently been nesting in more urban settings, perhaps to take advantage of often-abundant small birds on which they prey. 

Why do we study Short-tailed Hawks? Well, the species has no state or federal listing status and no monitoring program exists. In addition to their very small population size (last estimated at 250 pairs in the United States, almost all in Florida), several factors place Short-tailed Hawks at risk: a preference for nesting in large tracts of mature forest, the accelerating loss of historic nesting territories, concentrated winter distribution, specialized diet, and unusually low nesting success.

Bird by bird and nest by nest, we are gathering that information to answer these basic important questions and to help ensure that Short-tailed Hawks will persist into Florida’s future. See our website for more information on ARCI’s Short-tailed Hawk research.

For the last two years, we have been collaborating with the St. Petersburg Audubon Society as part of their “Raptors on the Move” program, which is directed by Dr. Gabe Vargo. In our first year, we tagged an adult female Swallow-tailed Kite, Sawgrass, with a GPS/GSM transmitter (GPS locations are sent to us via cell phone networks) and have been watching her migrate to Bolivia and back over the last 18 months.

Dr. Gabe Vargo, director of St. Peterburg Audubon Society's "Raptors on the Move" program, holds Dark Arrow. 
Photo by JoAnna Clayton, 2017.

In July 2016, knowing there was an active Short-tailed Hawk nesting territory at Sawgrass Lake Park in Pinellas County, Florida, we began trying to capture and tag an adult Short-tailed Hawk to add to "Raptors on the Move". After many trapping attempts with various methods that spanned 10 months, we FINALLY succeeded when a beautiful dark-morph adult flew into our net on 23 May 2017. We’ve named this bird - most likely a male based on its size - “Dark Arrow” because “Dark” is its color morph, and “Arrow” is the name of the lake closest to the capture site in Sawgrass Lake Park.

Gina Kent of ARCI fits Dark Arrow with a GPS/GSM transmitter while Dr. Gabe Vargo safely holds the raptor. This transmitter uses the cellular network to send and receive data.
Photo by JoAnna Clayton, 2017.

Dark Arrow spent the rest of the summer at Sawgrass Lake Park, where he and his dark-morph mate fledged a dark morph juvenile. Many of its foraging destinations lie about 4.5 miles east of the Weedon Island Preserve. 

When the winds picked up with oncoming Hurricane Irma, Dark Arrow returned to Sawgrass Lake Park to sit it out in a more densely forested location away from the coast. This hawk’s tracking data suggest he was restless through the stormy night, apparently moving from one wind-tossed tree to another, possibly looking for stronger branches on which to perch in the 70 mph wind gusts.

Dark Arrow is now back in his familiar nest-season surroundings, between Weedon Island Preserve and Sawgrass Lake Park. We are curious to see what he will do for the rest of the winter. Will he migrate to south Florida as do many Short-tailed Hawks, or will he stay in Pinellas County? Short-tailed Hawks are seen throughout the year at Sawgrass Lake Park, but most undergo a true migration within the state of Florida for the winter months. Because there is a plethora of urban birds to feed on year-round in the county and nesting conditions there appear to be ideal, he may stay put to maintain ownership of his territory. Only time will tell. We will share the tracking data with you as it accumulates. 

Friday, September 29, 2017

Go With the Wind; A Swallow-tailed Kite gets the best migration conditions

WOW! Apopka, the rehabilitated Swallow-tailed Kite with the GPS/GSM-transmitter, made it safely to Central America. Was Apopka lucky, or did it know a change in the weather loomed? We believe it was the latter. Birds detect variation in barometric pressure and other subtle weather characteristics, sensing change well before us humans. We believe Apopka was more ready than ever to begin migrating to South America, and the strong northern winds on the west side of Hurricane Irma came just at the right time.

Since 5 August, Apopka had been feeding, fattening, and preparing for 5,000 miles of migration in a remote portion of Brevard County, Florida. On 6 September, just three days before the brunt of Hurricane Irma ravaged the area, Apopka headed south. Hurricanes are low-pressure weather systems that circulate in a counter-clockwise direction. The immense size of this storm resulted in favorable winds over a large portion of Florida, and Apopka took advantage of the opportunity. 

On the first night after leaving its roosting/foraging area in Brevard County, Apopka stayed in St. Lucia County, continuing to Big Cypress National Preserve for last day and night in the United States before leaving the Everglades and heading out to sea from Florida’s southwestern shore on 8 September. The winds were definitely picking up in advance of Hurricane Irma as Apopka crossed the Straits of Florida. It only took four hours, at an average speed of 30 miles per hour, to reach the northern coast of Cuba, near the resort town of Varadero. By this time, Hurricane Irma was a Category 5 Hurricane and just 200 miles away. 

The sustained southbound winds carried Apopka across the width of Cuba to the southwestern part of the Zapata Peninsula, which is a large, protected natural area where swamp forests and wetlands meet coastal marshes. Twenty-four hours later, the eye of Irma passed over Varadero with sustained winds of  125 mph while Apopka, only 80 miles away, held tight through maximum winds of 50 mph.  Apopka stayed on the Zapata Peninsula through more stormy weather for seven days, then spent two nights on the Isle of Youth (Isla de la Juventud) off the southwestern coast gaining strength and fat reserves to complete the ocean crossing to the Yucat√°n Peninsula. 

Apopka made that final ocean crossing on 17 September with a safe landfall in the state of Quintana Roo, Mexico, 18 hours later. Having since followed tracks similar to all the Swallow-tailed Kites before it, it is already in Honduras.

The hard part is over for Apopka, the remaining migration is all over land. This rehabilitated bird’s survival is a true success story with or without a major hurricane (see our blog posted on 1 September 2017). We are so happy that Apopka is doing well, and grateful to the rehabilitators at Avian Reconditioning Center for investing their time, resources, and practiced care in this once-injured Swallow-tailed Kite. We particularly thank Carol McCorkle and Paula Ashby. 

Generous donations towards the cost of the tagging operation, transmitter, and data acquisition came from:

The City of Apopka - Mayor Joe Kilsheimer
Halifax Audubon - David Hartgrove
Oklawaha Audubon - Stacy Kelly
Seminole County Audubon - Lewis Gray, Margaret Terwilliger, Sarah Donlan
Tampa Bay Raptor Rescue - Barbara Walker
Clearwater Audubon - matching the challenge issued by Tampa Bay Raptor Rescue
West Volusia Audubon - Stephen Kintner
Deborah Green from Orange Audubon (personal donation)
Janet Marks from West Volusia Audubon (personal donation)
Eileen Tramontana, Director of Trout Lake Nature Center (personal donation)
Sandie Selman from West Volusia Audubon (personal donation)
Disney Volunteers from ARC, Rebecca Grimm and Alyssa Karnitz

Monday, September 25, 2017

A Snail of a Tale: radio-tagged Snail Kites and Hurricane Irma

In 2012, ARCI deployed satellite transmitters on twelve Snail Kites in peninsular Florida to study their movements in relation to habitat availability, site preferences, and use of publicly-owned conservation areas relative to unmanaged lands of various uses and conditions. Five years later, four of these birds are still providing the data that will help us inform critical management decisions for their species. These data have highlighted the Snail Kite’s refined adaptations for nomadism: we’ve seen the kites venture to other foraging or known nesting sites in a matter of hours and stay for weeks, months or, sometimes just hours.

Radio-tagged male Snail Kite on a power line.
Photo credit Jack Haxby 2017.
Because we have become so impressed with the kites’ extensive knowledge of the landscape gained from thousands of miles of traveling, we expected that these individuals had selected safe places to wait out Hurricane Irma. In fact, three of the four Snail Kites, all adult females, stayed in place as the storm came onshore in south Florida. One female, Harns hunkered down just 5 miles south of Harns Marsh in Lehigh Acres, her original capture location. The other two females, Okee Female and Citrus, chose to stay near Immokalee, Florida, a small agricultural town that was experiencing power outages, food shortages, and flooding long after the storm. Miraculously, these Snail Kites outlasted the eye of the then Category 3 hurricane, despite winds up to 129 miles an hour passing through that very area.  

The fourth kite, adult male Hwy 441 1, made some last minute adjustments to his evacuation plan. On 6 September, as Hurricane Irma was wreaking havoc on the Caribbean and a mandatory evacuation was imposed on Florida Keys’ residents, he was south of Loxahatchee, Florida, near Twentymile Bend in Palm Beach County.  On 8 September, he flew southwest to a freshwater marsh that is Snail Kite habitat just north of Tamiami Trail in Conservation Area 3A. However, on 10 September, as Irma drove on to Cudjoe Key, he zipped north 37 miles to a tiny tree island standing tall amidst wide-open marsh, where he weathered the storm. After a few days, well after the rain and winds had passed, Hwy 411 1 moved to within 3 miles of Okee Female just west of Immokalee, Florida, where he remains as of 20 September.

Locations of four tagged Snail Kites when Hurricane Irma made landfall on 11 September. 

We will be monitoring the birds’ data closely over the next few weeks to see how they will respond to elevated water levels in their favorite feeding places. Of course, it’s easy to understand how low water levels reduce snail densities and abundance - and thus the presence of Snail Kites - in the wet-prairie habitats of south Florida marshes. However, too-deep water covers normally-emergent vegetation, such as Spike Rush. Apple Snails climb up the stems of such wet-prairie plants to breathe at the water’s surface, thus becoming available to foraging Snail Kites. As water levels in Florida’s unforested wetlands recede, Snail Kites will be behaving again like the nomads they are, searching for the places with just the right set of conditions that increase snail availability and the foraging success of this highly adapted aerial predator.

Typical Snail Kite habitat in Conservation Area 3A in south Florida. Apple snails can be found
using emergent aquatic plants like Spike Rush (forefront) to breathe air from the surface,
 making them available to foraging kites.
Copyright Allan Eyestone/The Palm Beach Post 2017.

To see coarse, real-time movement maps of these four Snail Kites, remember you can follow them and our other satellite-tracked birds from our Satellite Tracking page on our website.

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.