The Florida Keys Hawkwatch is dedicated to promoting the appreciation and conservation of birds by committing to the long-term study of their migration through the Florida Keys.
The project currently monitors the migration of all avian species, with a focus on diurnal birds of prey from Curry Hammock State Park (56.2, Overseas Highway), and the morning flights of migratory land birds from Long Key State Park (67.5 of the Overseas Highway). Visitors and volunteers are welcome. For more information, contact project director Rafael Galvez at 305-804-6003 or TASpublisher@gmail.com.
Study Site Significance
The Florida Keys Hawkwatch (FKH) is the southernmost migration monitoring project in the continental United States. In terms of its history and scope, it is the sole project of its kind in the state of Florida and the southeast. By continually tracking the movements of birds as they prepare to cross the Florida Straits and Gulf of Mexico into the Caribbean – a region with a very low density of monitoring sites – it has long demonstrated its importance.
Few sites in the North American migration monitoring network have the conservation and ecological significance of FKH. The magnitude of its migration is not only one of the largest in the country (including migrants of 18 species, Lott 2006, Ruelas 2008), but one of the most important for falcons of three species. No other project in the world has documented higher numbers of Peregrine Falcons in a single day (651 on October 10, 2012) or an entire season – 3,836 during the fall or 2012. The project is one of the few to document the passage of Swallow-tailed and Mississippi Kites, and Short-tailed Hawks. Additionally, it is one of the few projects documenting the movements of important non-raptor species such as the threatened White-crowned Pigeon.
The Florida Keys extend from the southeastern tip of the Florida peninsula towards the southwest, about 170 km. The Florida Keys Hawkwatch conducts surveys from several locations in the Middle Keys, primarily Curry Hammock State Park on Little Crawl Key, a few miles northeast of the city of Marathon, and Long Key State Park in the city of Layton. Raptor migration monitoring in the Florida Keys has a long history involving day-counts at multiple locations by National Audubon in the late 80s through the 90s. These counts demonstrated that the flight of migratory raptors was most concentrated in the Middle Keys.
Diurnal birds of prey, or raptors, occupy the tops of several food chains, making them ideal indicators of environmental fluctuations. Because of their relatively large size and diurnal migratory habits, their passage tends to be more easily monitored compared to songbirds, which are smaller and migrate mostly at night. The study of raptors in the field has developed as science, conservation and recreation the world over, with hundreds of migration monitoring projects currently in North America. Most hawkwatches today use standards developed by the Hawk Migration Association of North America (HMANA) and add their seasonal data to www.HawkCount.org – an online repository generated by the organization. Long-term data from this online database is used to analyze raptor population trends.
The term “raptor” is commonly given to diurnal birds of prey, such as eagles, hawks and falcons. Of the 26 raptor species recorded in the state of Florida (5 still under review by the Florida Ornithological Society Records Committee), 20 have been documented from the Florida Keys. Seventeen of these species are regularly monitored during fall migration at the Florida Keys Hawkwatch (FKH), in Curry Hammock State Park, near Marathon.
Most raptors migrate seasonally during spring and fall. A prominent drive for this behavior is the seasonal change in food base. Raptor migration occurs primarily by day, mainly as a movement between latitudes, during which birds may cover long distances from “north” to “south” and vice versa.
Unlike waterfowl or passerines, most raptor species migrate singly, using a number of migratory flyways that are not necessarily the same during spring and fall. Raptors must save energy during migration in order to cover long distances; this can be achieved by using up-rising air currents, so-called thermals generated by sun-heated land surfaces. The Florida Keys are only a few inches above water, straddled between the Atlantic Ocean and Florida Bay – a flat ridge of limestone outcroppings curving towards the southwest, into the tropics. Although raptors regularly use updrafts – winds rising from hills or mountain slopes – to save energy, this is not the case anywhere in the Keys.
Over the Keys, raptors soar within columns of up-rising air currents. Height is continuously gained until the rising column cools down with altitude, and the birds must glide down to another newly formed column and start gaining height again. This way, a bird may cover up to 600 km (373 miles) per day. Because of this flight strategy and the fact that water surfaces do not generate rising air currents, most raptors avoid flying across water stretches wider than 25 km (15.5 miles). Following the narrow chain of the Keys, raptors have only a sliver of thermal-generating surface between two bodies of water.
Because of a considerable narrowing of landmass in the Middle Keys and a lack or alternate routes southward, the flight path of migratory birds of prey tends to be most concentrated there. Curry Hammock State Park was strategically selected as the location for the monitoring of raptor migration because of this factor. The Middle Keys tend to be no more than 1 km (0.62 mile) wide surrounding the FKH location, and offer a great vantage for the observation of birds of prey up to 2.5 km (1.6 miles) in distance.
The adopted population monitoring activities follow the standard protocols for data collection that are in use in more than 200 sites in North America (HMANA 2011). These migration counts consist of hourly records of a series of variables of weather and observation conditions, and its corresponding hourly tally of migrants recorded. These general standards are refined to fit the conditions of the flight at each site; e.g., FKH requires two observers during the field season, its optimal count period occurs between 15 September-15 November (in order to include ≥95% of the migration window for selected species), and specific instructions to document site routines are critical at this site, which experiences unique migration features.
Migration count data from most monitoring sites in the continent is stored in the online repository HawkCount.org – visit the site for recent information on counts at FKH during the current season. This electronic archive, managed by HMANA, is federated with other large observational data repositories such as Cornell University’s Avian Knowledge Network and the Global Biodiversity Information Facility, and provides safe and permanent archival with some analytical tools available for the general public, and data accessibility for research and conservation applications.