Kite Movements in the Florida Keys

Photo by Kevan Sunderland

Funding for Swallow-tailed Kite monitoring during the fall of 2014 was made possible through a gift by Juan Valadez and Laura Roselione. THANK YOU!

Four kite species have been documented from the Florida Keys Hawkwatch count site at Curry Hammock State Park since monitoring started in 1999. These include the Mississippi Kite (Ictinia mississippiensis), the Snail Kite (Rostrhamus sociabilis), and recently for the first time – the White-tailed Kite (Elanus leucurus). However, the beauty and grace emblematic of kites is perhaps best encapsulated in the Swallow-tailed Kite (Elanoides forficatus), an imperiled species that continues capturing our imagination – serving as symbol for wildlife management and conservation agencies throughout the state of Florida – and one that regularly graces the skies of the Florida Keys during fall migration.

SWALLOW-TAILED KITE

• Florida Keys Hawkwatch – Curry Hammock State Park
  • Count Site Species Average (1999 – 2013): 18
  • Highest Seasonal Count pre-2014 (1999 – 2013): 62 (2008)
    • 2014 Total: 256
    • Sept. 2-14, 2014: 190
    • Sept. 15 – Oct. 14, 2014: 66
• Preseason tally (August 2014) – Middle Keys: 37

All Swallow-tailed Kites breeding in the U.S. are migratory and leave the North American continent during the fall season. Their migratory movements start early compared to other diurnal raptors, and the species is already on the move southward by mid-July.

Few North American hawk migration count sites – like the Florida Keys Hawkwatch – are geographically positioned to allow for the monitoring of Swallow-tailed Kites during the fall. The breeding range of the species (Elanoides forficatus – subspecies forficatus) in the U.S. is now limited to southeastern states, primarily Florida and including portions of coastal Georgia and South Carolina, southern Alabama and Mississippi, and restricted areas in Louisiana and Texas. Despite their breeding throughout much of Florida, population trend assessments are limited by a lack of demographic data.

Unfortunately, the southeast also suffers from a low density of count sites for migratory birds of prey. According to HawkCount.org, the states of Georgia and Louisiana have no reporting, active or existing raptor migration counts. While the state of South Carolina has five registered count sites, none have a history of reporting any Swallow-tailed Kites during migration. The same can be said for two count sites registered for Alabama. In Texas it is a different story. The Smith Point count site overlooking Galveston Bay averages about 83 Swallow-tailed Kites per year over a period of 18 seasons, with as many as 202 kites counted during a single season (2008). Curiously, the Corpus Christi count site averages similarly over 18 seasons, with an average of 82 Swallow-tails per year, and a seasonal high of 349 (2008). The only other fall migration site in Texas reporting in HawkCount – Bentsen Rio Grande Valley State Park – has recorded the species on only three seasons out of 15, with no more than five in 2002. It is important to note that both the Smith Point and Corpus Christi sites start monitoring for raptors in August, and that traditionally, counts in the Florida Keys have not started until September 15, well past the expected peak dates for kites.

As can be seen from the chart above, both of these Texas count sites experience their peak passage dates for the species during roughly the third week of August. With Florida supporting an estimated 60% or more of the entire U.S. population (about 2500 to 4500 individuals at the end of breeding season), the count site in the Keys could expect to detect substantial flights of Swallow-tails starting early August.

While our project has understood that our traditional mid-September start date has resulted in lost opportunities for the monitoring of kites, we have been limited by challenges associated with an expansion of the count season.

The Difference that Two Additional Weeks Can Make

For the fall of 2014, our project made an effort to start the monitoring season significantly earlier than the traditional Sept. 15 start date. In addition to commencing monitoring at Curry Hammock with a full count team on Sept. 2 of this year, pre-season counting efforts were also carried out throughout the Middle Keys, from Long Key to Big Pine Key with the purpose of fine-tuning possible detection locations for greater numbers of Swallow-tailed Kites. The result from 10 days of counting during August 14-31 was 37 detected kites. While several of those birds were observed from various locations in northern Big Pine Key, many of the birds were detected within close proximity to Marathon, or near the hawkwatch count site at Curry Hammock, supporting the concept of adhering to a single site despite the potential for alternate detection locations.

However, the difference was most evident at our count site once full-day (8 hours minimum) operations commenced on September 2. The earlier two weeks of counting allowed us to detect 256 Swallow-tailed Kites (6-10% of the U.S. population), increasing our count 1300% above our site’s average.

As the project proceeds with plans for future seasons, we are encouraged by our efforts from 2014, reassured that counts from August through mid-September should render more kite detections. We will continue working on expanding our count period to include a time-frame better suited for the monitoring of Swallow-tailed Kites.

MISSISSIPPI KITE

Photo by Keven Sunderland

• Florida Keys Hawkwatch – Curry Hammock State Park
  • Count Site Species Average (1999 – 2013): 40
  • Highest Seasonal Count pre-2014 (1999 – 2013): 99 (2012)
    • 2014 Total: 128
    • Sept. 2-14, 2014: 15
    • Sept. 15 – Oct. 14, 2014: 113

Although our count site does not experience the number of Mississippi Kites seen in Texas and Central America, it is one of the few sites in North America that documents consistent numbers of the species during the fall. To illustrate the point, most hawk migration counts in the southeast average under two Mississippi Kites each fall season. A notable exception may be Congaree Bluffs in South Carolina, which averages about 15 birds a year, with as many as 76 kites documented in a single season (2003). When you consider the Mid-Atlantic region, no hawkwatch averages more than 2 kites a year according to data submitted via HawkCount.org.

With an average of 40 or more detections, and as many as 128 Mississippi Kites tallied during a single fall season, the Florida Keys Hawkwatch remains the highest count for the species in the eastern U.S.

With an earlier start to the season during 2014, we were able to add 15 birds that would have otherwise been missed during our traditional dates, increasing our highest count by about 30%. Future plans for the lengthening of the season by adding count days during the first half of September – and potentially August – could result in increased opportunities for the detection of migratory Mississippi Kites.

WHITE-TAILED KITE

Photo by Kerry Ross

• Florida Keys Hawkwatch – Curry Hammock State Park
  • Total: 1 (Oct. 17, 2014)

There has only been one White-tailed Kite documented as part of raptor migration counts in the Keys since standardized efforts started in the late 1980s. While the species breeds irregularly in the Southern Everglades, appearing to prefer the area surrounding Taylor Slough, Chekika and the adjacent agricultural areas in Homestead and Florida City, it is not a common species and little is understood about its life history and population status.

On 10/17/14 at roughly 11 am, the first and only White-tailed Kite detected as part of this project was observed flying southwestward over the Keys land chain. The species has been reported from Monroe County (Florida Keys) in the past, but to our knowledge, this is the only documented record (photo of the described individual above, taken by Kerry Ross).

Although the species tends to remains a year-round resident through much of its breeding range in North America, during nonbreeding season some birds may disperse and this may result in vagrancy and/or range expansion. Little is known about the Florida populations, whether the kites are migratory and/or nomadic.

In North America, the species may be currently experiencing its greatest distribution after a period of expansion. While populations are most concentrated in California, it was nearly extirpated from that state by the 1930s, and extinction had been predicted for the continent around that time.

In Florida, some of the oldest reports (1870s – 1890s) describe birds in the southern Gulf coast, from the area in current-day Naples down through Cape Sable. There are very few modern-day records of the species in that part of Florida. By the 1930s it was thought to be on the verge of extinction in the state, and it wasn’t until the 1980s that the species became established once again in South Florida.

SNAIL KITE

• Florida Keys Hawkwatch – Curry Hammock State Park
  • Total: 1 (Sept. 28, 2007)

Only one Snail Kite has been documented from Curry Hammock State Park during migratory raptor counts. Although the species is found from southern Mexico to Argentina, in the U.S. it is limited to restricted portions of Florida, where it is a year-round resident. The species – listed as Endangered in the state and federal registers – is considered nonmigratory, but may respond to habitat changes by engaging in dispersal or seminomadic movements. There is currently no evidence to indicate that Snail Kites regularly fly between Florida and Cuba. However, the species is a common to rare year-round resident throughout much of Cuba.

During September 28, 2007, counters John Van Dort and Cole Wild observed the bird captured in the photograph shown above at roughly 2:10 pm. It is no surprise that this raptor caused initial confusion. The Florida Keys hold very little habitat suitable for Snail Kites, which prefer to forage over freshwater patches in search of their preferred food – snails of the genus Pomacea. While reports from the Everglades include brackish tracts from Paurotis Pond to Flamingo, the species is virtually undocumented in the Florida Keys.

For more information about the status and movements of Snail Kites, Swallow-tailed Kites and other bird species found in Florida, visit the Avian Research and Conservation Institute‘s website.