Wednesday, May 6, 2020

While Swallow-tailed Kites settle into summer ranges, we re-cap the importance of tracking their movements.

The Avian Research and Conservation Institute, together with Orleans Audubon (Louisiana), has been tracking Swallow-tailed Kites with GPS-transmitters to learn about breeding behavior, habitat use, roosting locations, their migratory path, and winter activity ranges in South America.

The nesting season is in full swing for Swallow-tailed Kites throughout the U.S. The map below shows nine kites on their breeding ranges.  We suspect all but Sanibel and Apopka have settled into nesting. Apopka has been using an area in Altamonte Springs for the last 3 years but has not shown signs of nest attendance.

Babcock was our first tracked kite to return to the U.S.  She immediately went to her former breeding area in Charlotte County, Florida, but we have not gotten any data since early March. The most likely explanation is that her transmitter exceeded its life expectancy.  Similarly, Sanibel’s radio stopped transmitting soon after he reached the Florida Panhandle and began making his way south.  We have not received data from him on his Sanibel Island nesting range, but our partners there are watching for a kite with a small “bump” on its back. Sanibel’s transmitter was not yet due to expire, but we remain hopeful that it might otherwise have failed and that he will still be spotted.

Five of our tagged males do appear to be nesting: PBC-ERM male, Sarasota, Suwannee, Ponchitolawa, and Pritchard.  Sawgrass was our latest GPS-tracked Swallow-tailed Kite to return to the U.S. and she appears to be settling into a familiar nesting area in Pinellas County, Florida.

Given ARCI’s small staff, and especially now with limited travel options, we are very grateful for our collaborator’s Eyes on Kites to help us monitor these GPS-tracked birds and other nesting kites on habitually used nesting areas.

It has been challenging these last nine months monitoring the 16 Swallow-tailed Kites that we were tracking at the end of the 2019 breeding season. Our study sample is now down to seven individuals. Most of the missing birds were carrying transmitters due to expire soon (see the next paragraph on related technical and cost considerations). Furthermore, every annual migration cycle poses serious risks to the kites’ survival. In fact, after monitoring years of annual migrations of tagged Swallow-tailed Kites, we would have expected that, on average, at least two or even three of the 16 birds that left the U.S. at the end of last summer (July-August 2019) would not survive to nest again in 2020. This reality, combined with the large number of kites recently carrying radios with imminent expiration dates, apparently has left us with a relatively sudden reduction in the number of transmitting kites.  As these birds face increasingly more severe storms, wildfires, habitat destruction, and persecution, it is more important than ever to be tracking these growing threats and conveying the impacts they are having on wildlife.

It is worth commenting here on the lifespan of the equipment we are now using to track Swallow-tailed Kites. Although cell-phone/GPS devices have storage batteries that repeatedly recharge via solar panels, these batteries, necessarily very small, can withstand only so many charge/recharge cycles before their stored energy is insufficient for transmission to cell towers (in our experience, lifespan has varied from about 1.5 to 3.0 years). The satellite/GPS devices we used more in the past last much longer (5.5 to 7.0 years), but they cost over three times as much per unit and tracking location.

Our trend toward using more cell/GPS tracking technology (i.e., accepting the trade-off between longer radio life versus being able to afford tagging more individuals) reflects our current research priorities for addressing the critical management and conservation needs of Swallow-tailed Kites. These include detecting losses of vital nesting, migration, and wintering habitats; discovering new and re-located pre-migration roosts sites, which support long-term population monitoring and require surveillance for human disturbance and habitat degradation; informing land-management practices that favor nesting, foraging, and wintering kites; and identifying anthropogenic sources of mortality throughout the year.

This last research need, which requires detecting when and where kites die, highlights the value of remotely tracking Swallow-tailed Kites. Human-induced changes in global climate regimes, the accelerating destruction of natural habitats by unsustainable economic and social conditions, and increasing applications of agricultural pesticides and herbicides harmful to wildlife are rapidly elevating the risks confronting the Swallow-tailed Kite’s U. S. breeding population all across their annual, 10,000-mile hemispheric range. Of particular concern are threats on their migratory and winter range– vast areas that lie beyond what we can observe and monitor directly. In the next two months, as we have periodically in the past, we will analyze all the satellite and cellular tracking data we have collected since 1996 to illuminate patterns in where and when mortality has occurred, and how these patterns may be shifting over time. What we learn will be posted on this site.

We hope that you enjoy these blogs and, like us, are inspired by each and every kite’s story. Our promise is to continue making the very careful, informed decisions needed to safely gather the data needed for science-based bird conservation. The benefits of remote tracking are enormous. However, as you can imagine, it is costly. As ARCI’s mission keeps growing in importance, so too do the challenges in raising the necessary financial support. Would you like to be part of our sponsoring team and join the list of ARCI’s supporters with a one-time or monthly donation? You can find more information on our Make a Gift page.

As always, we are grateful to all of the organizations and individuals who have made ARCI’s long-term studies of Swallow-tailed Kites possible, thus helping us understand how these amazing birds need our help. The ever-growing list of current contributors includes:

Audubon Center for Birds of Prey
Caloosa Bird Club
Clearwater Audubon Society
CROW - Clinic for the Rehabilitation of Wildlife, Inc.
Florida Panther National Wildlife Refuge
Friends of Palmetto Bluff Conservancy
Friends of the Carlton Reserve
Friends of the Florida Panther Refuge
Friends of the Lower Suwannee & Cedar Keys National Wildlife Refuges
Halifax River Audubon
Jacksonville Zoo and Gardens
Lower Suwannee National Wildlife Refuge
National Audubon Society
Oklawaha Valley Audubon Society
Orange Audubon Society
Orleans Audubon Society
Palm Beach County Department of Environmental Resources Management
Palm Beach Zoo
Palmetto Bluff Conservancy
Peace River Audubon Society
Sanibel-Captiva Audubon Society
Sanibel-Captiva Conservation Foundation SCCF
Sarasota Audubon Society
Seminole Audubon Society
St. Petersburg Audubon Society
Sunrise Wildlife Rehabilitation
The Avian Reconditioning Center for Birds of Prey
Venice Area Audubon Society
West Volusia Audubon